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  • 1.
    Aaboud, M.
    et al.
    Facult ́e des Sciences, Universit ́e Mohamed Premier and LPTPM, Oujda, Morocco.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellajosyula, Venugopal
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Gradin, P. O. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Isacson, Max F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael U.F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    De Bruin, P. H. Sales
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Zwalinski, L.
    CERN, Geneva, Switzerland.
    Properties of g -> b(b)over-bar at small opening angles in pp collisions with the ATLAS detector at root s=13 TeV2019In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 99, no 5, article id 052004Article in journal (Refereed)
    Abstract [en]

    The fragmentation of high-energy gluons at small opening angles is largely unconstrained by present measurements. Gluon splitting to b-quark pairs is a unique probe into the properties of gluon fragmentation because identified b-tagged jets provide a proxy for the quark daughters of the initial gluon. In this study, key differential distributions related to the g -> b (b) over bar process are measured using 33 fb(-1) of root s = 13 TeV pp collision data recorded by the ATLAS experiment at the LHC in 2016. Jets constructed from charged-particle tracks, clustered with the anti-k(t) jet algorithm with radius parameter R = 0.2, are used to probe angular scales below the R = 0.4 jet radius. The observables are unfolded to particle level in order to facilitate direct comparisons with predictions from present and future simulations. Multiple significant differences are observed between the data and parton shower Monte Carlo predictions, providing input to improve these predictions of the main source of background events in analyses involving boosted Higgs bosons decaying into b-quarks.

  • 2.
    Aaboud, M.
    et al.
    Faculté des SciencesUniversité Mohamed Premier and LPTPM Oujda Morocco.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Frate, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Gradin, P. O. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Isacson, Max F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael U.F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Sales De Bruin, Pedro H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Zwalinski, L.
    CERN Geneva Switzerland.
    Measurement of the photon identification efficiencies with the ATLAS detector using LHC Run 2 data collected in 2015 and 20162019In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 79, no 3, article id 205Article in journal (Refereed)
    Abstract [en]

    The efficiency of the photon identification criteria in the ATLAS detector is measured using 36.1 fb1 to 36.7 fb1 of pp collision data at v s = 13 TeV collected in 2015 and 2016. The efficiencies are measured separately for converted and unconverted isolated photons, in four different pseudorapidity regions, for transverse momenta between 10 GeV and 1.5 TeV. The results from the combination of three data-driven techniques are compared with the predictions from simulation after correcting the variables describing the shape of electromagnetic showers in simulation for the average differences observed relative to data. Data-tosimulation efficiency ratios are determined to account for the small residual efficiency differences. These factors are measured with uncertainties between 0.5% and 5% depending on the photon transverse momentum and pseudorapidity. The impact of the isolation criteria on the photon identification efficiency, and that of additional soft pp interactions, are also discussed. The probability of reconstructing an electron as a photon candidate ismeasured in data, and compared with the predictions from simulation. The efficiency of the reconstruction of photon conversions is measured using a sample of photon candidates from Z. mu mu. events, exploiting the properties of the ratio of the energies deposited in the first and second longitudinal layers of the ATLAS electromagnetic calorimeter.

  • 3.
    Aaboud, M.
    et al.
    Univ Mohamed Premier, Fac Sci, Oujda, Morocco; LPTPM, Oujda, Morocco.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Frate, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Gradin, P. O. Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Isacson, Max F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael U.F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Sales De Bruin, Pedro
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Zwalinski, L.
    CERN, Geneva, Switzerland.
    Search for Higgs boson pair production in the (WWWW(*))-W-(*) decay channel using ATLAS data recorded at root s=13 TeV2019In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 5, article id 124Article in journal (Refereed)
    Abstract [en]

    A search for a pair of neutral, scalar bosons with each decaying into two W bosons is presented using 36.1 fb(-1) of proton-proton collision data at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider. This search uses three production models: non-resonant and resonant Higgs boson pair production and resonant production of a pair of heavy scalar particles. Three final states, classified by the number of leptons, are analysed: two same-sign leptons, three leptons, and four leptons. No significant excess over the expected Standard Model backgrounds is observed. An observed (expected) 95% confidence-level upper limit of 160 (120) times the Standard Model prediction of non-resonant Higgs boson pair production cross-section is set from a combined analysis of the three final states. Upper limits are set on the production cross-section times branching ratio of a heavy scalar X decaying into a Higgs boson pair in the mass range of 260 GeV m(X) 500 GeV and the observed (expected) limits range from 9.3 (10) pb to 2.8 (2.6) pb. Upper limits are set on the production cross-section times branching ratio of a heavy scalar X decaying into a pair of heavy scalars S for mass ranges of 280 GeV m(X) 340 GeV and 135 GeV m(S) 165 GeV and the observed (expected) limits range from 2.5 (2.5) pb to 0.16 (0.17) pb.

  • 4.
    Aaboud, M.
    et al.
    Univ Mohamed Premier, Fac Sci, Oujda, Morocco; LPTPM, Oujda, Morocco.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Frate, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Gradin, P. O. Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Isacson, Max F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael U.F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Sales De Bruin, Pedro
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Zwalinski, L.
    CERN, Geneva, Switzerland.
    Search for top-quark decays t -> Hq with 36 fb(-1) of pp collision data at root s=13 TeV with the ATLAS detector2019In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 5, article id 123Article in journal (Refereed)
    Abstract [en]

    A search for flavour-changing neutral current decays of a top quark into an up-type quark (q = u, c) and the Standard Model Higgs boson, t Hq, is presented. The search is based on a dataset of pp collisions at = 13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 36.1 fb(-1). Two complementary analyses are performed to search for top-quark pair events in which one top quark decays into Wb and the other top quark decays into Hq, and target the Hbb and H (+-) decay modes, respectively. The high multiplicity of b-quark jets, or the presence of hadronically decaying -leptons, is exploited in the two analyses respectively. Multivariate techniques are used to separate the signal from the background, which is dominated by top-quark pair production. No significant excess of events above the background expectation is found, and 95% CL upper limits on the t Hq branching ratios are derived. The combination of these searches with ATLAS searches in diphoton and multilepton final states yields observed (expected) 95% CL upper limits on the t Hc and t Hu branching ratios of 1.1 x 10(-3) (8.3 x 10(-4)) and 1.2 x 10(-3) (8.3 x 10(-4)), respectively. The corresponding combined observed (expected) upper limits on the |(tcH)| and |(tuH)| couplings are 0.064 (0.055) and 0.066 (0.055), respectively.

  • 5.
    Aaboud, M.
    et al.
    Facult ́e des Sciences, Universit ́e Mohamed Premier and LPTPM, Oujda, Morocco.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Gradin, P. O. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Isacson, Max F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael U.F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    De Bruin, P. H. Sales
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Zwalinski, L.
    CERN, Geneva, Switzerland.
    Search for heavy long-lived multicharged particles in proton-proton collisions at root s=13 TeV using the ATLAS detector2019In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 99, no 5, article id 052003Article in journal (Refereed)
    Abstract [en]

    A search for heavy long-lived multicharged particles is performed using the ATLAS detector at the LHC. Data with an integrated luminosity of 36.1 fb(-1) collected in 2015 and 2016 from proton-proton collisions at root s = 13 TeV are examined. Particles producing anomalously high ionization, consistent with long-lived massive particles with electric charges from vertical bar q vertical bar = 2e to vertical bar q vertical bar = 7e, are searched for. No events are observed, and 95% confidence level cross-section upper limits are interpreted as lower mass limits for a Drell-Yan production model. Multicharged particles with masses between 50 and 980-1220 GeV (depending on their electric charge) are excluded.

  • 6.
    Aaboud, M.
    et al.
    Facult ́e des Sciences, Universit ́e Mohamed Premier and LPTPM, Oujda, Morocco.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Gradin, P. O. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Isacson, Max F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael U.F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    De Bruin, P. H. Sales
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Zwalinski, L.
    CERN, Geneva, Switzerland.
    Search for long-lived particles produced in pp collisions at root s=13 TeV that decay into displaced hadronic jets in the ATLAS muon spectrometer2019In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 99, no 5, article id 052005Article in journal (Refereed)
    Abstract [en]

    A search for the decay of neutral, weakly interacting, long-lived particles using data collected by the ATLAS detector at the LHC is presented. The analysis in this paper uses 36.1 fb(-1) of proton-proton collision data at root s =13 TeV recorded in 2015-2016. The search employs techniques for reconstructing vertices of long-lived particles decaying into jets in the muon spectrometer exploiting a two-vertex strategy and a novel technique that requires only one vertex in association with additional activity in the detector that improves the sensitivity for longer lifetimes. The observed numbers of events are consistent with the expected background and limits for several benchmark signals are determined.

  • 7.
    Aaboud, M.
    et al.
    Université Cadi Ayyad, LPHEA-Marrakech; Faculté des Sciences.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Gradin, P. O. Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Isacson, Max F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael U. F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Sales De Bruin, Pedro
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Zwalinski, L.
    CERN, Geneva; Switzerland.
    Search for large missing transverse momentum in association with one top-quark in proton-proton collisions at s=13 TeV with the ATLAS detector2019In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 5, article id 041Article in journal (Refereed)
    Abstract [en]

    This paper describes a search for events with one top-quark and large missing transverse momentum in the final state. Data collected during 2015 and 2016 by the ATLAS experiment from 13 TeV proton-proton collisions at the LHC corresponding to an integrated luminosity of 36.1 fb(-1) are used. Two channels are considered, depending on the leptonic or the hadronic decays of the W boson from the top quark. The obtained results are interpreted in the context of simplified models for dark-matter production and for the single production of a vector-like T quark. In the absence of significant deviations from the Standard Model background expectation, 95% confidence-level upper limits on the corresponding production cross-sections are obtained and these limits are translated into constraints on the parameter space of the models considered.

  • 8.
    Aaboud, M.
    et al.
    Faculté des Sciences Université Mohamed Premier and LPTPM, Oujda, Morocco.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Gradin, P. O. Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Isacson, Max F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael U.F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Sales De Bruin, Pedro
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Zwalinski, L.
    CERN Geneva Switzerland.
    Measurements of inclusive and differential fiducial cross-sections of t(t)over-bar gamma production in leptonic final states at root s=13 TeV in ATLAS2019In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 79, no 5, article id 382Article in journal (Refereed)
    Abstract [en]

    Inclusive and differential cross-sections for the production of a top-quark pair in association with a photon are measured with proton-proton collision data corresponding to an integrated luminosity of 36.1fb-1, collected by the ATLAS detector at the LHC in 2015 and 2016 at a centre-of-mass energy of 13TeV. The measurements are performed in single-lepton and dilepton final states in a fiducial volume. Events with exactly one photon, one or two leptons, a channel-dependent minimum number of jets, and at least one b-jet are selected. Neural network algorithms are used to separate the signal from the backgrounds. The fiducial cross-sections are measured to be 521 +/- 9(stat.)+/- 41(sys.)fb and 69 +/- 3(stat.)+/- 4(sys.) fb for the single-lepton and dilepton channels, respectively. The differential cross-sections are measured as a function of photon transverse momentum, photon absolute pseudorapidity, and angular distance between the photon and its closest lepton in both channels, as well as azimuthal opening angle and absolute pseudorapidity difference between the two leptons in the dilepton channel. All measurements are in agreement with the theoretical predictions.

  • 9.
    Aaboud, M.
    et al.
    Univ Mohamed Premier, Fac Sci, Oujda, Morocco; LPTPM, Oujda, Morocco.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Gradin, P. O. Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Isacson, Max F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael U.F.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Sales De Bruin, Pedro
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Zwalinski, L.
    CERN, Geneva, Switzerland.
    Search for heavy charged long-lived particles in the ATLAS detector in 36.1 fb(-1) of proton-proton collision data at root s=13 Te V2019In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 99, no 9, article id 092007Article in journal (Refereed)
    Abstract [en]

    A search for heavy charged long-lived particles is performed using a data sample of 36.1 fb(-1) of protonproton collisions at root s = 13 TeV collected by the ATLAS experiment at the Large Hadron Collider. The search is based on observables related to ionization energy loss and time of flight, which are sensitive to the velocity of heavy charged particles traveling significantly slower than the speed of light. Multiple search strategies for a wide range of lifetimes, corresponding to path lengths of a few meters, are defined as model independently as possible, by referencing several representative physics cases that yield long-lived particles within supersymmetric models, such as gluinos/squarks (R-hadrons), charginos and staus. No significant deviations from the expected Standard Model background are observed. Upper limits at 95% confidence level are provided on the production cross sections of long-lived R-hadrons as well as directly pair-produced staus and charginos. These results translate into lower limits on the masses of long-lived gluino, sbottom and stop R-hadrons, as well as staus and charginos of 2000, 1250, 1340, 430, and 1090 GeV, respectively.

  • 10. Aaboud, M.
    et al.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Gradin, P. O. Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Isacson, Max
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Sales De Bruin, Pedro
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Zwalinski, L.
    Combined measurement of differential and total cross sections in the H -> gamma gamma and the H -> ZZ* -> 4l decay channels at root s=13 TeV with the ATLAS detector2018In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 786, p. 114-133Article in journal (Refereed)
    Abstract [en]

    A combined measurement of differential and inclusive total cross sections of Higgs boson production is performed using 36.1 fb(-1) of 13 TeV proton-proton collision data produced by the LHC and recorded by the ATLAS detector in 2015 and 2016. Cross sections are obtained from measured H -> gamma gamma and H -> ZZ* -> 4l event yields, which are combined taking into account detector efficiencies, resolution, acceptances and branching fractions. The total Higgs boson production cross section is measured to be 57.0(-5.9)(+6.0) (stat.) (+4.0)(-3.3) (syst.) pb, in agreement with the Standard Model prediction. Differential cross-section measurements are presented for the Higgs boson transverse momentum distribution, Higgs boson rapidity, number of jets produced together with the Higgs boson, and the transverse momentum of the leading jet. The results from the two decay channels are found to be compatible, and their combination agrees with the Standard Model predictions.

  • 11. Aaboud, M.
    et al.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Gradin, P. O. Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Isacson, Max
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Sales De Bruin, Pedro
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Zwalinski, L.
    Observation of H -> b(b)over-bar decays and V H production with the ATLAS detector2018In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 786, p. 59-86Article in journal (Refereed)
    Abstract [en]

    A search for the decay of the Standard Model Higgs boson into a b (b) over bar pair when produced in association with a W or Z boson is performed with the ATLAS detector. The data, corresponding to an integrated luminosity of 79.8 fb(-1) were collected in proton-proton collisions during Run 2 of the Large Hadron Collider at a centre-of-mass energy of 13 TeV. For a Higgs boson mass of 125 GeV, an excess of events over the expected background from other Standard Model processes is found with an observed (expected) significance of 4.9 (4.3) standard deviations. A combination with the results from other searches in Run 1 and in Run 2 for the Higgs boson in the bb decay mode is performed, which yields an observed (expected) significance of 5.4 (5.5) standard deviations, thus providing direct observation of the Higgs boson decay into b-quarks. The ratio of the measured event yield for a Higgs boson decaying into b (b) over bar to the Standard Model expectation is 1.01 +/- 0.12(stat.) (-0.15) (+0.16)(syst.). Additionally, a combination of Run 2 results searching for the Higgs boson produced in association with a vector boson yields an observed (expected) significance of 5.3 (4.8) standard deviations. (C) 2018 The Author(s). Published by Elsevier B.V.

  • 12. Aaboud, M.
    et al.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Gradin, P. O. Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Isacson, Max
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Sales De Bruin, Pedro
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Zwalinski, L.
    Search for lepton-flavor violation in different-flavor, high-mass final states in pp collisions at root s=13 TeV with the ATLAS detector2018In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, no 9, p. 1-34, article id 092008Article in journal (Refereed)
    Abstract [en]

    A search is performed for a heavy particle decaying into different-flavor, dilepton pairs (e mu, e tau or mu tau), using 36.1 fb(-1) of proton-proton collision data at root s = 13 TeV collected in 2015-2016 by the ATLAS detector at the Large Hadron Collider. No excesses over the Standard Model predictions are observed. Bayesian lower limits at the 95% credibility level are placed on the mass of a Z' boson, the mass of a supersymmetric tau-sneutrino, and on the threshold mass for quantum black-hole production. For the Z' and sneutrino models, upper cross-section limits are converted to upper limits on couplings, which are compared with similar limits from low-energy experiments and which are more stringent for the e tau and mu tau modes.

  • 13. Aaboud, M.
    et al.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Gradin, P. O. Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Isacson, Max
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Sales De Bruin, Pedro
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Zwalinski, L.
    Search for lepton-flavor-violating decays of the Z boson into a r lepton and a light lepton with the ATLAS detector2018In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, no 9, article id 092010Article in journal (Refereed)
    Abstract [en]

    Direct searches for lepton flavor violation in decays of the Z boson with the ATLAS detector at the LHC are presented. Decays of the Z boson into an electron or muon and a hadronically decaying r lepton are considered. The searches are based on a data sample of proton-proton collisions collected by the ATLAS detector in 2015 and 2016, corresponding to an integrated luminosity of 36.1 fb(-1) at a center-of-mass energy of root s = 13 TeV. No statistically significant excess of events above the expected background is observed, and upper limits on the branching ratios of lepton-flavor-violating decays are set at the 95% confidence level: B(Z -> e tau) < 5.8 x 10(-5) and B(Z -> mu tau) < 2.4 x 10(-5). This is the first limit on B(Z -> e tau) with ATLAS data. The upper limit on 13(Z -> mu tau) is combined with a previous ATLAS result based on 20.3 fb(-1) of proton protoncollision data at a center-of-mass energy of root s = 8 TeV and the combined upper limit at 95% confidence level is B(Z -> mu tau) < 1.3 x 10(-5).

  • 14. Aaboud, M.
    et al.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Gradin, P. O. Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Isacson, Max
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Sales De Bruin, Pedro
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Zwalinski, L.
    Searches for exclusive Higgs and Z boson decays into J/psi gamma, psi (2S) gamma, and Upsilon(nS) gamma at root s=13 TeV with the ATLAS detector2018In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 786, p. 134-155Article in journal (Refereed)
    Abstract [en]

    Searches for the exclusive decays of the Higgs and Z bosons into a J/psi, psi(2S), or Upsilon(nS) (n = 1, 2, 3) meson and a photon are performed with a pp collision data sample corresponding to an integrated luminosity of 36.1 fb(-1) collected at root s = 13 TeV with the ATLAS detector at the CERN Large Hadron Collider. No significant excess of events is observed above the expected backgrounds, and 95% confidence- level upper limits on the branching fractions of the Higgs boson decays to J/psi gamma, psi(2S) gamma and Upsilon(nS) gamma of 3.5 x 10(-4), 2.0 x 10(-3), and (4.9, 5.9, 5.7) x 10(-4), respectively, are obtained assuming Standard Model production. The corresponding 95% confidence-level upper limits for the branching fractions of the Z boson decays are 2.3 x 10(-6), 4.5 x 10(-6) and (2.8, 1.7, 4.8) 10(-6), respectively. (C) 2018 The Author. Published by Elsevier B.V.

  • 15. Aaboudd, M.
    et al.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Gradin, P. O. Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Isacson, Max
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Sales De Bruin, Pedro
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Zwalinski, L.
    Constraints on off-shell Higgs boson production and the Higgs boson total width in ZZ -> 4l and ZZ -> 2l2v final states with the ATLAS detector2018In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 786, p. 223-244Article in journal (Refereed)
    Abstract [en]

    A measurement of off-shell Higgs boson production in the ZZ -> 4l and ZZ -> 2l2v decay channels, where stands for either an electron or a muon, is performed using data from proton-proton collisions at a centre-of-mass energy of root s = 13 TeV. The data were collected by the ATLAS experiment in 2015 and 2016 at the Large Hadron Collider, and they correspond to an integrated luminosity of 36.1 fb(-1). An observed (expected) upper limit on the off-shell Higgs signal strength, defined as the event yield normalised to the Standard Model prediction, of 3.8 (3.4) is obtained at 95% confidence level (CL). Assuming the ratio of the Higgs boson couplings to the Standard Model predictions is independent of the momentum transfer of the Higgs production mechanism considered in the analysis, a combination with the on-shell signal-strength measurements yields an observed (expected) 95% CL upper limit on the Higgs boson total width of 14.4 (15.2) MeV.

  • 16. Aad, G.
    et al.
    Asimakopoulou, Eleni M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bergeås Kuutmann, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Bokan, Petar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ellajosyula, Venugopal
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ellert, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ferrari, Arnaud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Isacson, Max
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Mårtensson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    De Bruin, P. H. Sales
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Zwalinski, L.
    Observation of Light-by-Light Scattering in Ultraperipheral Pb plus Pb Collisions with the ATLAS Detector2019In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 123, no 5, article id 052001Article in journal (Refereed)
    Abstract [en]

    This Letter describes the observation of the light-by-light scattering process, gamma gamma -> gamma gamma, in Pb + Pb collisions at root S-NN = 5.02 TeV. The analysis is conducted using a data sample corresponding to an integrated luminosity of 1.73 nb(-1), collected in November 2018 by the ATLAS experiment at the LHC. Light-by-light scattering candidates are selected in events with two photons produced exclusively, each with transverse energy E-T(gamma) > 3 GeV and pseudorapidity vertical bar eta(gamma)vertical bar < 2.4, diphoton invariant mass above 6 GeV, and small diphoton transverse momentum and acoplanarity. After applying all selection criteria, 59 candidate events are observed for a background expectation of 12 +/- 3 events. The observed excess of events over the expected background has a significance of 8.2 standard deviations. The measured fiducial cross section is 78 +/- 13(stat) +/- 7(syst) +/- 3(lumi) nb.

  • 17.
    Ali, Hasan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Eriksson, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Li, Hu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jafri, S. Hassan M.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Kumar, M. S. Sharath
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ögren, Jim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ziemann, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    An electron energy loss spectrometer based streak camera for time resolved TEM measurements2017In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 176, p. 5-10Article in journal (Refereed)
    Abstract [en]

    We propose an experimental setup based on a streak camera approach inside an energy filter to measure time resolved properties of materials in the transmission electron microscope (TEM). In order to put in place the streak camera, a beam sweeper was built inside an energy filter. After exciting the TEM sample, the beam is swept across the CCD camera of the filter. We describe different parts of the setup at the example of a magnetic measurement. This setup is capable to acquire time resolved diffraction patterns, electron energy loss spectra (EELS) and images with total streaking times in the range between 100 ns and 10 μs.

  • 18.
    Antonova, M.
    et al.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia.;Moscow Engn Phys Inst, Kashirskoe Shosse 31, Moscow, Russia..
    Asfandiyarov, R.
    Univ Geneva, DPNC, Quai Ernest Ansermet 24, Geneva, Switzerland..
    Bayes, R.
    Univ Glasgow, Sch Phys & Astron, Kelvin Bldg, Glasgow, Lanark, Scotland..
    Benoit, P.
    CERN, European Org Nucl Res, CH-1211 Geneva 23, Switzerland..
    Blondel, A.
    Univ Geneva, DPNC, Quai Ernest Ansermet 24, Geneva, Switzerland..
    Bogomilov, M.
    Univ Sofia, Dept Phys, James Bourchier Blvd 5, Sofia, Bulgaria..
    Bross, A.
    Fermilab Natl Accelerator Lab, Kirk Rd & Pine St, Batavia, IL 60510 USA..
    Cadoux, F.
    Univ Geneva, DPNC, Quai Ernest Ansermet 24, Geneva, Switzerland..
    Cervera, A.
    CSIC, IFIC, Calle Catedrat Jose Beltran 2, Valencia, Spain.;Univ Valencia, Calle Catedrat Jose Beltran 2, Valencia, Spain..
    Chikuma, N.
    Univ Tokyo, Int Ctr Elementary Particle Phys, Bunkyo Ku, 7-3-1 Hongo, Tokyo, Japan..
    Dudarev, A.
    CERN, European Org Nucl Res, CH-1211 Geneva 23, Switzerland..
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Favre, Y.
    Univ Geneva, DPNC, Quai Ernest Ansermet 24, Geneva, Switzerland..
    Fedotov, S.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia..
    Hallsjo, S-P
    Izmaylov, A.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia..
    Karadzhov, Y.
    Univ Geneva, DPNC, Quai Ernest Ansermet 24, Geneva, Switzerland..
    Khabibullin, M.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia..
    Khotyantsev, A.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia..
    Kleymenova, A.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia..
    Koga, T.
    Univ Tokyo, Int Ctr Elementary Particle Phys, Bunkyo Ku, 7-3-1 Hongo, Tokyo, Japan..
    Kostin, A.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia..
    Kudenko, Y.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia.;Moscow Inst Phys & Technol, 9 Inst Skiy Per, Dolgoprudnyi, Moscow Region, Russia.;Moscow Engn Phys Inst, Kashirskoe Shosse 31, Moscow, Russia..
    Likhacheva, V.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia..
    Martinez, B.
    Univ Geneva, DPNC, Quai Ernest Ansermet 24, Geneva, Switzerland..
    Matev, R.
    Univ Sofia, Dept Phys, James Bourchier Blvd 5, Sofia, Bulgaria..
    Medvedeva, M.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia..
    Mefodiev, A.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia.;Moscow Inst Phys & Technol, 9 Inst Skiy Per, Dolgoprudnyi, Moscow Region, Russia..
    Minamino, A.
    Yokohama Natl Univ, 79-8 Tokiwadai, Yokohama, Kanagawa, Japan..
    Mineev, O.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia..
    Nessi, M.
    CERN, European Org Nucl Res, CH-1211 Geneva 23, Switzerland..
    Nicola, L.
    Univ Geneva, DPNC, Quai Ernest Ansermet 24, Geneva, Switzerland..
    Noah, E.
    Univ Geneva, DPNC, Quai Ernest Ansermet 24, Geneva, Switzerland..
    Ovsiannikova, T.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia..
    Da Silva, H. Pais
    CERN, European Org Nucl Res, CH-1211 Geneva 23, Switzerland..
    Parsa, S.
    Univ Geneva, DPNC, Quai Ernest Ansermet 24, Geneva, Switzerland..
    Rayner, M.
    CERN, European Org Nucl Res, CH-1211 Geneva 23, Switzerland..
    Rolando, G.
    CERN, European Org Nucl Res, CH-1211 Geneva 23, Switzerland..
    Shaykhiev, A.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia..
    Simion, Patrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Soler, F. J. P.
    Univ Glasgow, Sch Phys & Astron, Kelvin Bldg, Glasgow, Lanark, Scotland..
    Suvorov, S.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia..
    Tsenov, R.
    Univ Sofia, Dept Phys, James Bourchier Blvd 5, Sofia, Bulgaria..
    Ten Kate, H.
    CERN, European Org Nucl Res, CH-1211 Geneva 23, Switzerland..
    Vankova-Kirilova, G.
    Univ Sofia, Dept Phys, James Bourchier Blvd 5, Sofia, Bulgaria..
    Yershov, N.
    Russian Acad Sci, Inst Nucl Res, 60 October Revolution Pr 7a, Moscow, Russia..
    Baby MIND: a magnetized segmented neutrino detector for the WAGASCI experiment2017In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 12, article id C07028Article in journal (Refereed)
    Abstract [en]

    T2K (Tokai-to-Kamioka) is a long-baseline neutrino experiment in Japan designed to study various parameters of neutrino oscillations. Anear detector complex (ND280) is located 280m downstream of the production target and measures neutrino beam parameters before any oscillations occur. ND280's measurements are used to predict the number and spectra of neutrinos in the Super-Kamiokande detector at the distance of 295 km. The difference in the target material between the far (water) and near (scintillator, hydrocarbon) detectors leads to the main non-cancelling systematic uncertainty for the oscillation analysis. In order to reduce this uncertainty a new WAter-Grid-And-SCintillator detector (WAGASCI) has been developed. A magnetized iron neutrino detector (Baby MIND) will be used to measure momentum and charge identification of the outgoing muons from charged current interactions. The Baby MIND modules are composed of magnetized iron plates and long plastic scintillator bars read out at the both ends with wavelength shifting fibers and silicon photomultipliers. The front-end electronics board has been developed to perform the readout and digitization of the signals from the scintillator bars. Detector elements were tested with cosmic rays and in the PS beam at CERN. The obtained results are presented in this paper.

  • 19.
    Bhattacharyya, Anirban
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Hoang, Long
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ziemann, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Lofnes, Tor
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Li, Han
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Goryashko, Vitaliy
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Precise measurements of hot S-parameters of superconducting cavities: Experimental setup and error analysisManuscript (preprint) (Other academic)
    Abstract [en]

    Superconducting accelerating cavities used in modern particle accelerators change their intrinsic properties when excited to very high field levels close to the critical field where the superconductivity is affected. In this report we describe a test-bench and data analysis procedure to determine the so-called hot S-parameters from strongly driven cavities and use them to quantify the properties of the cavity at varying field levels. The method is based on analysing reflection coefficient for a large number of configurations in a self-excited loop setup and determining the cavity coupling coefficient $\kappa=Q_0/Q_{ext}$ as a function of cavity voltage to high accuracy. Since $Q_{ext}$ is determined independently and is a constant, from the information of $\kappa$ the Q-slope can be determined.

  • 20.
    Bhattacharyya, Anirban
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ögren, Jim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Holz, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ziemann, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Wave propagation in a fractal wave guide2017In: in Proceedings of the 8th International Particle Accelerator Conference (IPAC 2017), Copenhagen, Denmark, May, 2017., 2017Conference paper (Other academic)
  • 21.
    Boholm Kylesten, Karl-Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Numerical methods for design of the transfer line of the ESSnuSB project: Independent Project in Engineering Physics2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    ESS neutrino Super Beam (ESSnuSB) is a project that aim to create ahigh energy beam of neutrinos and anti-neutrinos to study thephenomenon neutrino oscillation and learn more about symmetryviolations in quantum mechanics. To create the neutrino beam, negativeHydrogen ions must be transported from the ESS linear accelerator at2.5 GeV, to a proton accumulation ring. This is done through a transferline, that shall direct the ion beam while preserve the beam as much aspossible. In thisproject, there was an attempt at finding a design for this transferline. Preferably, the line consists of a long main line of FODO cellsand two matching sections at each end. A simulation of the beam wasdone that gives the progression beta and dispersion functions,statistical measurements of the particle distribution, through a partof the transfer line. A design for the main line was found. For tuningthe quadrupole magnets, an iterative method using the system's responsematrix was used. However, it could not match more than four parametersat the time, while six was required for complete matching. Because ofthis, it is not able to match thedispersion.

  • 22.
    Book, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    1kW Class-E solid state power amplifier for cyclotron RF-source2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis discusses the design, construction and testing of a highefficiency, 100 MHz, 1 kW, Class-E solid state power amplifier. The design was performed with the aid of computer simulations using electronic design software (ADS). The amplifier was constructed around Ampleon's BLF188XR LDMOS transistor in a single ended design. The results for 100 MHz operation show a power added efficiency of 82% at 1200 W pulsed power output. For operation at 102 MHz results show a power added efficiency of 86% at 1050 W pulsed power output. Measurements of the drain- and gate voltage waveforms provide validation of Class-E operation.

  • 23.
    Book, Stefan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Hoang Duc, Long
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Design, fabrication and measurement of 1kW Class-E amplifier at 100 MHz2018Conference paper (Other academic)
  • 24.
    Carlile, Colin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    The Editor-in-Chief's parting words2017In: Journal of Neutron Research, ISSN 1023-8166, E-ISSN 1477-2655, Vol. 19, no 3-4, p. 85-85Article in journal (Other academic)
  • 25.
    Chen, Z.
    et al.
    Stanford Univ, Dept Phys, Stanford, CA 94305 USA.
    Higley, D. J.
    Stanford Univ, Dept Appl Phys, Stanford, CA 94305 USA.
    Beye, M.
    DESY, Dept Photon Sci, Notkestr 85, D-22607 Hamburg, Germany.
    Hantschmann, M.
    Helmholtz Zentrum Berlin, Dept Mat & Energy Sci, D-14109 Berlin, Germany.
    Mehta, V
    HGST, San Jose Res Ctr, San Jose, CA 95135 USA.
    Hellwig, O.
    Tech Univ Chemnitz, Inst Phys, D-09107 Chemnitz, Germany;Helmholtz Zentrum Dresden Rossendorf, Inst Ion Beam Phys & Mat Res, D-01328 Dresden, Germany.
    Mitra, A.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA;Univ Warwick, Dept Phys, Coventry CV4 7AL, W Midlands, England.
    Bonetti, S.
    Stockholm Univ, Dept Phys, S-10691 Stockholm, Sweden.
    Bucher, M.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Carron, S.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Chase, T.
    Stanford Univ, Dept Appl Phys, Stanford, CA 94305 USA.
    Jal, E.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Kukreja, R.
    Univ Calif Davis, Dept Mat Sci & Engn, Davis, CA 95616 USA.
    Liu, T.
    Stanford Univ, Dept Phys, Stanford, CA 94305 USA.
    Reid, A. H.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Dakovski, G. L.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Foehlisch, A.
    Helmholtz Zentrum Berlin, Dept Mat & Energy Sci, D-14109 Berlin, Germany.
    Schlotter, W. F.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Dürr, Hermann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Stöhr, J.
    SLAC Natl Accelerator Lab, Stanford, CA 94035 USA;Dept Photon Sci, Stanford, CA 94035 USA.
    Ultrafast Self-Induced X-Ray Transparency and Loss of Magnetic Diffraction2018In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 121, no 13, article id 137403Article in journal (Refereed)
    Abstract [en]

    Using ultrafast similar or equal to 2.5 fs and similar or equal to 25 fs self-amplified spontaneous emission pulses of increasing intensity and a novel experimental scheme, we report the concurrent increase of stimulated emission in the forward direction and loss of out-of-beam diffraction contrast for a Co/Pd multilayer sample. The experimental results are quantitatively accounted for by a statistical description of the pulses in conjunction with the optical Bloch equations. The dependence of the stimulated sample response on the incident intensity, coherence time, and energy jitter of the employed pulses reveals the importance of increased control of x-ray free electron laser radiation.

  • 26.
    Dancila, Dragos
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Hoang Duc, Long
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Jobs, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Holmberg, Måns
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Hjort, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    A compact 10 kW solid-state RF power amplifier at 352 MHz2017Conference paper (Refereed)
  • 27.
    Dancila, Dragos
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Uppsala University.
    Hoang Duc, Long
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Jobs, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Holmberg, Måns
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Hjort, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    A compact 10 kW solid-state RF power amplifier at 352 MHz2017In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 874, article id 012093Article in journal (Refereed)
    Abstract [en]

    A compact 10 kW RF power amplifier at 352 MHz was developed at FREIA for the European Spallation Source, ESS. The specifications of ESS for the conception of amplifiers are related to its pulsed operation: 3.5 ms pulse length and a duty cycle of 5%. The realized amplifier is composed of eight kilowatt level modules, combined using a planar Gysel 8-way combiner. The combiner has a low insertion loss of only 0.2 dB, measured at 10 kW peak power. Each module is built around a commercially available LDMOS transistor in a single-ended architecture. During the final tests, a total output peak power of 10.5 kW was measured.

  • 28.
    Dittmeier, Sebastian
    et al.
    Physics Institute, Heidelberg University, Germany.
    Brenner, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Gustafsson, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Yang, Shiming
    Univ Wuppertal, Inst High Frequency & Commun Technol, Wuppertal, Germany.
    Wireless data transmission for high energy physics applications2017In: EPJ Web of Conferences, ISSN 2101-6275, E-ISSN 2100-014X, Vol. 150, article id 00002Article in journal (Refereed)
    Abstract [en]

    Silicon tracking detectors operated at high luminosity collider experiments pose a challenge for current and future readout systems regarding bandwidth, radiation, space and power constraints. With the latest developments in wireless communications, wireless readout systems might be an attractive alternative to commonly used wired optical and copper based readout architectures.

    The WADAPT group (Wireless Allowing Data and Power Transmission) has been formed to study the feasibility of wireless data transmission for future tracking detectors. These proceedings cover current developments focused on communication in the 60 GHz band. This frequency band offers a high bandwidth, a small form factor and an already mature technology. Motivation for wireless data transmission for high energy physics application and the developments towards a demonstrator prototype are summarized. Feasibility studies concerning the construction and operation of a wireless transceiver system have been performed. Data transmission tests with a transceiver prototype operating at even higher frequencies in the 240 GHz band are described. Data transmission at rates up to 10 Gb/s have been obtained successfully using binary phase shift keying.

  • 29.
    Ekman, Johannes
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Beam-Beam Simuleringar genomatt Använda Avbildningar för Andra Momentet av Strålningsspridningar2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Kolliderare är en typ av partikelaccelerator som används till att kollidera subatomiska partiklar och är viktiga för utförandet av experiment i partikel- och kärnfysik. Laddade partiklar accelereras och hålls i separata omloppsbanor med dipol- och kvadrupolmagneter, och deras banor korsar varandra minst en gång. De laddade partiklar som åker i en omloppsbana kan generaliseras till en laddad partikelstråle. Dessa strålar propagerar åt motsatta håll, och när dessa kolliderar rakt in i varandra, är laddningarna så tätt fördelade att dess elektriska fält påverkar partiklarna i den motgående strålen. Denna så kallade beam-beam effekt begränsar prestandan på kolliderare, och det är därför av intresse att kunna beskriva denna effekt med en såprecis modell som möjligt. I denna rapport testas en modell av beam-beam effekten som baserar sig på en modell som beskrevs av M. A. Furman, K. Y. Ng och A. W. Chao i rapporten "A Symplectic Model of Coherent Beam-Beam Quadrupole Modes"från 1988, men med en ändring på hur de elektriska fälten påverkar de laddade partiklarna. Denna modell testas därefter mot Furmans modell, och den nya modellen utvärderas. Den nya modellen ger stabilare strålningsspridningar under inverkan av beam-beam effekten jämfört med Furmans modell.

  • 30.
    Fahlström, Simon
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Hamberg, Mathias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Simulations of Magnetic Fields and Forces in Highly Adjustable Magnet (HAM) Undulator Concept Using COMSOL2019Report (Other academic)
    Abstract [en]

    A design for a new type of undulator insertion device has been proposed. The undulator would consist of a stack of disks that each contain a pair of magnet structures, each disk being a half period of the minimum planar case. The disks could rotate independently about the beam axis, and the distance of the magnets from the center line is adjustable, so the magnetic field is adjustable in magnitude and orientation within the transverse plane along the beam axis. This would allow the undulator to be configured for generating a wide variety of radiation. Plane polarization would be attained with undulator periods as integer multiples of the base period. In the base case the direction of magnetization alternates between each disk, and for the case of multiple periods the magnetization alternates each M:th disk. Helical polarization would be attained with a period greater than two times the base period such that an integer number of periods fit inside the undulator structure. Initial numerical simulations have been made, and are reported in this paper. Building on a previous study [1] further simulations were requested to study the behavior of the magnets closer, and to calculate the forces acting on the magnet structures for use in feasibility assessment. In the previous study simple magnetic structures with uniform direction of magnetization were simulated. In this study a more complex structure was also investigated: a type of partial transverse Halbach configuration. This structure would concentrate the magnetic flux along the beamline and could lead to a more compact design, and limit the magnetic field outside the device.The simulations were made using COMSOL Multiphysics modelling software.

  • 31. Farabolini, W.
    et al.
    Peauger, F.
    Borgmann, C.
    Ögren, Jim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ruber, R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Corsini, R.
    Gamba, D.
    Grudiev, A.
    Khan, M. A.
    Mazzoni, S.
    Quirante, J. L. Navarro
    Pan, R.
    Towler, J.
    Vitoratou, N.
    Yaqub, K.
    Recent Results from CTF3 Two Beam Test Stand2014In: Proceedings, 5th International Particle Accelerator Conference (IPAC 2014): Dresden, Germany, June 15-20, 2014, 2014Conference paper (Other academic)
  • 32.
    Goryashko, Vitaliy A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Quasi-half-cycle pulses of light from a tapered undulator2017In: PHYSICAL REVIEW ACCELERATORS AND BEAMS, ISSN 2469-9888, Vol. 20, no 8, article id 080703Article in journal (Refereed)
    Abstract [en]

    Strong-field few-cycle terahertz (THz) pulses are an invaluable tool for engineering highly non-equilibrium states of matter. A scheme is proposed to generate quasi-half-cycle GV/m-scale THz pulses with a multikilohertz repetition rate. It makes use of coherent spontaneous emission from a prebunched electron beam traversing an optimally tapered undulator. The scheme is the further development of the slippage control in free-electron lasers [T. Tanaka, Phys. Rev. Lett. 114, 044801 (2015)]. An explicit condition for the spectral amplitude of undulator radiation and a phase condition for the electron density distribution, required for the generation of desired pulses, are presented. The amplitude condition is met by proper undulator tapering, and a generic optimal undulator profile is found analytically. In order to meet the phase condition, the distance between the adjacent bunches is varied according to the instantaneous resonant undulator wavelength. A 3D analytical theory is complemented by a detailed numerical study based on a direct solution to the 3D wave equation.

  • 33.
    Goryashko, Vitaliy A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Bhattacharyya, Anirban
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Li, Han
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Roger, Ruber
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    A Method for High-Precision Measurements of Superconducting Cavities2017Conference paper (Refereed)
  • 34.
    Goryashko, Vitaliy
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Jobs, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Hoang, Long
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Eriksson, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala Univ, Dept Phys & Astron, S-75120 Uppsala, Sweden..
    12-Way 100 kW Reentrant Cavity-Based Power Combiner With Doorknob Couplers2018In: IEEE Microwave and Wireless Components Letters, ISSN 1531-1309, E-ISSN 1558-1764, Vol. 28, no 2, p. 111-113Article in journal (Refereed)
    Abstract [en]

    We present radio frequency (RF) and thermal characterization of a compact 12-way power combiner designed for operation at 352 MHz at a power level of 100 kW with 5% duty factor. The combiner is based on a reentrant cavity with 12 input doorknob couplers and one output coupler that is integrated with the post of the cavity and forms doorknob type geometry. We introduce convenient design formulas that allow easy identification of a suitable parameter space, which is then refined with numerical simulations. Low-power RF measurements of a prototype show 0.2% insertion loss and a relative rms amplitude imbalance between the ports of 0.1% and phase imbalance of 0.036 degrees rms. The matching is better than -25 dB over a 3-dB bandwidth around the design frequency. We also tested the combiner up to 200 kW and found the RF loss to be comparable to that of the low-power measurement. In a long test run at 100 kW with 5% duty factor, the combiner temperature stabilized at 10 degrees above ambient.

  • 35.
    Gray, A. X.
    et al.
    Temple Univ, Dept Phys, Philadelphia, PA 19122 USA;SLAC Natl Accelerator Lab, Stanford Inst Mat & Energy Sci, Menlo Pk, CA 94025 USA.
    Hoffmann, M. C.
    SLAC Natl Accelerator Lab, Linac Coherent Light Source, Menlo Pk, CA 94025 USA.
    Jeong, J.
    IBM Almaden Res Ctr, San Jose, CA 95120 USA.
    Aetukuri, N. P.
    IBM Almaden Res Ctr, San Jose, CA 95120 USA.
    Zhu, D.
    SLAC Natl Accelerator Lab, Linac Coherent Light Source, Menlo Pk, CA 94025 USA.
    Hwang, H. Y.
    MIT, Dept Chem, Cambridge, MA 02139 USA.
    Brandt, N. C.
    MIT, Dept Chem, Cambridge, MA 02139 USA.
    Wen, H.
    Argonne Natl Lab, Adv Photon Source, Argonne, IL 60439 USA.
    Sternbach, A. J.
    Univ Calif San Diego, Dept Phys, La Jolla, CA 92093 USA;Boston Univ, Dept Phys, 590 Commonwealth Ave, Boston, MA 02215 USA.
    Bonetti, S.
    SLAC Natl Accelerator Lab, Stanford Inst Mat & Energy Sci, Menlo Pk, CA 94025 USA.
    Reid, A. H.
    SLAC Natl Accelerator Lab, Stanford Inst Mat & Energy Sci, Menlo Pk, CA 94025 USA.
    Kukreja, R.
    Stanford Univ, Dept Mat Sci & Engn, Stanford, CA 94305 USA;SLAC Natl Accelerator Lab, Stanford Inst Mat & Energy Sci, Menlo Pk, CA 94025 USA.
    Graves, C.
    Stanford Univ, Dept Appl Phys, Stanford, CA 94305 USA;SLAC Natl Accelerator Lab, Stanford Inst Mat & Energy Sci, Menlo Pk, CA 94025 USA.
    Wang, T.
    Stanford Univ, Dept Mat Sci & Engn, Stanford, CA 94305 USA;SLAC Natl Accelerator Lab, Stanford Inst Mat & Energy Sci, Menlo Pk, CA 94025 USA.
    Granitzka, P.
    Univ Amsterdam, Van der Waals Zeeman Inst, NL-1018 XE Amsterdam, Netherlands;SLAC Natl Accelerator Lab, Stanford Inst Mat & Energy Sci, Menlo Pk, CA 94025 USA.
    Chen, Z.
    Stanford Univ, Dept Phys, Stanford, CA 94305 USA;SLAC Natl Accelerator Lab, Stanford Inst Mat & Energy Sci, Menlo Pk, CA 94025 USA.
    Higley, D. J.
    Stanford Univ, Dept Appl Phys, Stanford, CA 94305 USA;SLAC Natl Accelerator Lab, Stanford Inst Mat & Energy Sci, Menlo Pk, CA 94025 USA.
    Chase, T.
    Stanford Univ, Dept Appl Phys, Stanford, CA 94305 USA;SLAC Natl Accelerator Lab, Stanford Inst Mat & Energy Sci, Menlo Pk, CA 94025 USA.
    Jal, E.
    SLAC Natl Accelerator Lab, Stanford Inst Mat & Energy Sci, Menlo Pk, CA 94025 USA.
    Abreu, E.
    Swiss Fed Inst Technol, Inst Quantum Elect, CH-8006 Zurich, Switzerland;Boston Univ, Dept Phys, 590 Commonwealth Ave, Boston, MA 02215 USA.
    Liu, M. K.
    Boston Univ, Dept Phys, 590 Commonwealth Ave, Boston, MA 02215 USA;SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA.
    Weng, T-C
    SLAC Natl Accelerator Lab, Stanford Synchrotron Radiat Lightsource, Menlo Pk, CA 94025 USA.
    Sokaras, D.
    SLAC Natl Accelerator Lab, Stanford Synchrotron Radiat Lightsource, Menlo Pk, CA 94025 USA.
    Nordlund, D.
    SLAC Natl Accelerator Lab, Stanford Synchrotron Radiat Lightsource, Menlo Pk, CA 94025 USA.
    Chollet, M.
    SLAC Natl Accelerator Lab, Linac Coherent Light Source, Menlo Pk, CA 94025 USA.
    Alonso-Mori, R.
    SLAC Natl Accelerator Lab, Linac Coherent Light Source, Menlo Pk, CA 94025 USA.
    Lemke, H.
    SLAC Natl Accelerator Lab, Linac Coherent Light Source, Menlo Pk, CA 94025 USA.
    Glownia, J. M.
    SLAC Natl Accelerator Lab, Linac Coherent Light Source, Menlo Pk, CA 94025 USA.
    Trigo, M.
    SLAC Natl Accelerator Lab, Stanford Inst Mat & Energy Sci, Menlo Pk, CA 94025 USA.
    Zhu, Y.
    Argonne Natl Lab, Adv Photon Source, Argonne, IL 60439 USA.
    Ohldag, H.
    SLAC Natl Accelerator Lab, Stanford Synchrotron Radiat Lightsource, Menlo Pk, CA 94025 USA.
    Freeland, J. W.
    Argonne Natl Lab, Adv Photon Source, Argonne, IL 60439 USA.
    Samant, M. G.
    IBM Almaden Res Ctr, San Jose, CA 95120 USA.
    Berakdar, J.
    Martin Luther Univ Halle Wittenberg, Inst Phys, D-06099 Halle, Germany.
    Averitt, R. D.
    Univ Calif San Diego, Dept Phys, La Jolla, CA 92093 USA;Boston Univ, Dept Phys, 590 Commonwealth Ave, Boston, MA 02215 USA.
    Nelson, K. A.
    MIT, Dept Chem, Cambridge, MA 02139 USA.
    Parkin, S. S. P.
    IBM Almaden Res Ctr, San Jose, CA 95120 USA.
    Dürr, Hermann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. SLAC Natl Accelerator Lab, Stanford Inst Mat & Energy Sci, Menlo Pk, CA 94025 USA.
    Ultrafast terahertz field control of electronic and structural interactions in vanadium dioxide2018In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 98, no 4, article id 045104Article in journal (Refereed)
    Abstract [en]

    Vanadium dioxide (VO2), an archetypal correlated-electron material, undergoes an insulator-metal transition near room temperature that exhibits electron-correlation-driven and structurally driven physics. Using ultrafast temperature- and fluence-dependent optical spectroscopy and x-ray scattering, we show that multiple interrelated electronic and structural processes in the nonequilibrium dynamics in VO2 can be disentangled in the time domain. Specifically, following intense subpicosecond terahertz (THz) electric-field excitation, a partial collapse of the insulating gap occurs within the first picosecond. At temperatures sufficiently close to the transition temperature and for THz peak fields above a threshold of approximately 1 MV/cm, this electronic reconfiguration initiates a change in lattice symmetry taking place on a slower timescale. We identify the kinetic energy increase of electrons tunneling in the strong electric field as the driving force, illustrating a promising method to control electronic and structural interactions in correlated materials on an ultrafast timescale.

  • 36.
    Hamberg, Mathias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Vargas Catalan, Ernesto
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ögren, Jim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Jacewicz, Marek
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Kuittinen, M.
    Institute of Photonics, University of Eastern Finland, Finland.
    Vartiainen, I.
    Institute of Photonics, University of Eastern Finland, Finland.
    Dielectric Laser Acceleration Setup Design, Grating Manufacturing and Investigations Into Laser Induced RF Cavity Breakdowns2017In: Proceedings of FEL2017, Santa Fe, NM, USA, 2017Conference paper (Refereed)
  • 37.
    Hoang Duc, Long
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Bhattacharyya, Anirban
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Goryashko, Vitaliy
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Olsson, Jörgen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Time Domain Characterization of High Power Solid State Amplifiers for the Next Generation Linear Accelerators2018In: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 60, no 1, p. 163-171Article in journal (Refereed)
    Abstract [en]

    This paper presents the time domain characterization of high power pulsed solid state amplifiers to be used forlinear accelerator applications. The study comprises nonlinear circuit envelope simulations and time domainenvelope measurements. Measurements and simulations are performed under the pulsed conditions (3.5 mspulse width, 5% duty cycle) specific to the European Spallation Source (ESS) high intensity proton accelerator.We measure the characteristics of pulsed LDMOS based power amplifiers such as: pulse droop along the pulse,efficiency, average envelope pulse amplitude and phase, pulse drain current waveform, pulse drain voltagewaveform, etc. A comparison between the measured results and the simulated results is also presented. Inaddition to the pulse profile characterization, the pulse to pulse (P2P) stability of the presented solid state poweramplifier (SSPA) is investigated as variations of amplitude and phase. The P2P stability simulations areintroduced as a combination of the Monte-Carlo simulations and the nonlinear circuit envelope simulations. Thesimulated results are used for fitting the P2P measurements to give an early insight of causes of instabilities ofthe nonlinear LDMOS models.

  • 38.
    Hoang Duc, Long
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Bhattacharyya, Anirban
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Olsson, Jörgen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Implementation of a Highly Efficient Solid State RF Power Source for Superconducting Cavities2018Conference paper (Other academic)
  • 39.
    Hoang Duc, Long
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Bhattacharyya, Anirban
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Olsson, Jörgen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Optimal Power Consumption during the Charging of Superconducting Cavities using Drain Voltage Modulation of Solid State Power Amplifiers2018Conference paper (Other academic)
  • 40.
    Hoang Duc, Long
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Nguyen Dinh The, Anh
    Vietnam National University (VNU), Hanoi, Vietnam.
    Bach Gia, Duong
    Vietnam National University (VNU), Hanoi, Vietnam.
    Jobs, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    A new high-power low-loss air-dielectric stripline Gysel divider/combiner for particle accelerator applications at 352 MHz2018In: IET Control Theory & Applications, ISSN 1751-8644, E-ISSN 1751-8652, no 5, p. 264-267Article in journal (Refereed)
    Abstract [en]

    This study presents a new two-way Gysel combiner based on an air-dielectric stripline which allows to handle very high radio-frequency power levels with low-loss suitable for power combination in accelerator applications. The insertion loss of the combiner is 0.1 dB (2%). A thick stripline implementation allows improving the power capability in both continuous wave (CW) and pulsed operation. In addition, a mechanical tuner allows compensating for assembly and fabrication discrepancies. A methodology of designing the Gysel combiner as well as high-power measurements up to 22 kW in pulsed mode are presented. Simulations and measurements are in very good agreement.

  • 41.
    Holz, Michael
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ziemann, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Analytic Space-Charge Model for Gaussian Beams with cross-plane Coupling2017Report (Other academic)
    Abstract [en]

    Intensities of particle beams provided by particle accelerators are raised to levels where the self-interaction of the beam particles due to electromagnetic repulsion, the so-called space-charge effect, becomes a dominant factor. It is therefore indispensable to understand the effects on the beam dynamics in the presence of strong space charge forces. As complement to existing simulation methods, we present a fully analytic space charge model valid for transverse Gaussian beams and which includes non-linear space charge forces and cross-plane coupling. We verify the validity of the model by running test simulations in a few accelerator lattice examples. Finally, we briefly explore the possibilities for future simulations regarding new insights in beam dynamics and show initial results of the development of a beam envelope (core) in a test ring, as well as the dynamics of passive spectator particles which observe the non-linear electric field generated by a beam core.

  • 42.
    Iacocca, E.
    et al.
    Univ Colorado, Dept Appl Math, Boulder, CO 80309 USA;NIST, Boulder, CO 80305 USA;Chalmers Univ Technol, Dept Phys, Div Theoret Phys, S-41296 Gothenburg, Sweden.
    Liu, T-M
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Reid, A. H.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Fu, Z.
    Tongji Univ, Sch Phys Sci & Engn, Shanghai 200092, Peoples R China.
    Ruta, S.
    Univ York, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Granitzka, P. W.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Jal, E.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Bonetti, S.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA;Stockholm Univ, Dept Phys, S-10691 Stockholm, Sweden;Ca Foscari Univ Venice, Dept Mol Sci & Nanosyst, I-30172 Venice, Italy.
    Gray, A. X.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA;Temple Univ, Dept Phys, 1925 N 12th St, Philadelphia, PA 19122 USA.
    Graves, C. E.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Kukreja, R.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Chen, Z.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Higley, D. J.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Chase, T.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Le Guyader, L.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA;European Xray Free Electron Laser Facil GmbH, Spect & Coherent Scattering, Holzkoppel 4, D-22869 Schenefeld, Germany.
    Hirsch, K.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Ohldag, H.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Schlotter, W. F.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Dakovski, G. L.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Coslovich, G.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Hoffmann, M. C.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Carron, S.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Tsukamoto, A.
    Nihon Univ, Dept Elect & Comp Sci, 7-24-1 Narashino Dai Funabashi, Chiba 2748501, Japan.
    Kirilyuk, A.
    Radboud Univ Nijmegen, Inst Mol & Mat, Heyendaalseweg 135, NL-6525 AJ Nijmegen, Netherlands.
    Kimel, A. V.
    Radboud Univ Nijmegen, Inst Mol & Mat, Heyendaalseweg 135, NL-6525 AJ Nijmegen, Netherlands.
    Rasing, Th.
    Radboud Univ Nijmegen, Inst Mol & Mat, Heyendaalseweg 135, NL-6525 AJ Nijmegen, Netherlands.
    Stöhr, J.
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Evans, R. F. L.
    Univ York, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Ostler, T.
    Univ Liege, Phys Mat & Nanostruct, B-4000 Sart Tilman Par Liege, Belgium;Sheffield Hallam Univ, Fac Arts Comp Engn & Sci, Howard St, Sheffield S1 1WB, S Yorkshire, England.
    Chantrell, R. W.
    Univ York, Dept Phys, York YO10 5DD, N Yorkshire, England;Radboud Univ Nijmegen, Inst Mol & Mat, Heyendaalseweg 135, NL-6525 AJ Nijmegen, Netherlands.
    Hoefer, M. A.
    Univ Colorado, Dept Appl Math, Boulder, CO 80309 USA.
    Silva, T. J.
    NIST, Boulder, CO 80305 USA.
    Dürr, Hermann A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.
    Spin-current-mediated rapid magnon localisation and coalescence after ultrafast optical pumping of ferrimagnetic alloys2019In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, article id 1756Article in journal (Refereed)
    Abstract [en]

    Sub-picosecond magnetisation manipulation via femtosecond optical pumping has attracted wide attention ever since its original discovery in 1996. However, the spatial evolution of the magnetisation is not yet well understood, in part due to the difficulty in experimentally probing such rapid dynamics. Here, we find evidence of a universal rapid magnetic order recovery in ferrimagnets with perpendicular magnetic anisotropy via nonlinear magnon processes. We identify magnon localisation and coalescence processes, whereby localised magnetic textures nucleate and subsequently interact and grow in accordance with a power law formalism. A hydrodynamic representation of the numerical simulations indicates that the appearance of noncollinear magnetisation via optical pumping establishes exchange-mediated spin currents with an equivalent 100% spin polarised charge current density of 107 A cm-2. Such large spin currents precipitate rapid recovery of magnetic order after optical pumping. The magnon processes discussed here provide new insights for the stabilization of desired meta-stable states.

  • 43.
    Jacewicz, Marek
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Dark currents studies with the Uppsala X-band Spectrometer at XBox test stand at CERN2019Report (Other academic)
    Abstract [en]

    Vacuum arcs is the phenomenon which limits the performance of normal conducting acceleratorcavities. It closely depends on electron field emission, which is consider a precursor for the creationof a vacuum discharge. These processes are still not fully understood, but we know that theydepend on the physical properties of the surfaces and bulk materials used in the acceleratorstructures. We need to come at these problems with a multidisciplinary approach, comprisingaccelerator, material and surface physics, for both experimental and theoretical analysis.The field emission current emitted during operation of the RF cavity is typically refer to as thedark current. Behavior of the dark current can give useful information about changes inside thestructure during conditioning and thus into the physics of the vacuum arcs. The Uppsala groupuses a magnetic spectrometer to look at the changes, both spatially on the screen and by measuringthe energy spectrum of the escaping electrons during conditioning of CLIC X-band structuresin dedicated high-power RF test stand at CERN. The spectrometer was originally designedto measure the electrons from the breakdown events with much higher intensities than the darkcurrent signals. In this paper we present the attempt to measure the dark current with the samesetup.

  • 44.
    Jobs, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Eriksson, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    An 8-1 Single-Stage 10-kW Planar Gysel Power Combiner at 352 MHz2018In: IEEE Transactions on Components, Packaging, and Manufacturing Technology, ISSN 2156-3950, E-ISSN 2156-3985, Vol. 8, no 5, p. 851-857Article in journal (Refereed)
    Abstract [en]

    A compact single-stage 8-1 Gysel Combiner in planar technology for operation with 352-MHz pulses with peak output power of 10 kW has been designed, manufactured, and tested. The module has 0.2-dB insertion loss when operated at nominal power, and the return loss of all ports is 20 dB or better. The module was operated using 3.3-ms pulses at 14-Hz repetition rate without any signs of degradation, thermal heating, or arcing. The new design makes use of inclusions of weakly coupled lines in the common point section of the Gysel combiner. It is possible to adjust port imbalances caused by parasitic line coupling in the system for optimum performance at a given frequency by adjusting the coupling.

  • 45.
    Johannsdotter, Sigridur
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Design of the Cryocooled DC Discharge System with Heat Transfer Simulations in COMSOL2017Report (Other academic)
    Abstract [en]

    Vacuum breakdowns are major limiting factor for the development of the compactparticle accelerators. Further progress in this domain requires studies of thevacuum breakdowns in well controlled environment, where all important parameters,like mate- rial temperature, can be regulated. Cryocooled DC spark system is one ofthe projects that addresses these demands and it is first setup where temperaturewill be controlled through a wide range, from room temperatures all the way downto 4 K. The main topics of this project are simulations of the cool down time of thepulsed DC system done in the physics simulation software COMSOL. The simulationresults are bench- marked through theoretical calculations. Two design aresimulated and compared, one with a simpli?ed geometry and one with the modelimported from CAD. Both models are of comparable dimensions and bothsimulations yields similar cool down time and the simulations are thereforeconsistent. The simulations are made in order to choose a cryocooler for thesystem. The cryocooler needs to be able to cool down the system in a short enoughtime, as well as keep the system at a certain temperature. The cool down time usingtwo different cryocoolers with different cooling capacities is evaluated, and thecryocooler with the higher capacity also cools down the system quicker. The time tocool down the electrodes from 45 K to 4 K with a cryocooler of 1.5 W coolingcapacity is 7.8 hours, as opposed to the cryocooler with 0.2 W cooling capacityyielding a cool down time of 58.5 hours.

  • 46.
    Lander, Gerry
    et al.
    Inst Laue Langevin, 71 Ave Martyrs CS 20156, F-38042 Grenoble 9, France.
    Carlile, Colin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Biographical Item: B. T. M. (Terry) Willis (1927-2018), In Journal Of Neutron Research, 20:1-2, p. 41-422018Other (Other (popular science, discussion, etc.))
  • 47.
    Li, Han
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Bhattacharyya, Anirban
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Hermansson, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Jobs, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Santiago-Kern, Rocio
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    High power testing of the first ESS Spoke cavity Package2017In: Proceedings of the 18th International Conference on RF Superconductivity, 2017Conference paper (Other academic)
    Abstract [en]

    The first double spoke cavity for the ESS project was tested with high power in the HNOSS cryostat at the FREIA Laboratory.  This cavity is designed for 325.21MHz, pulsed mode with 14 Hz repetition rate, up to a peak power of 360 kW. The qualification of the cavity package in a horizontal test, involving a superconducting spoke cavity, a fundamental power coupler (FPC), LLRF system and RF station, represents an important verification before the module assembly. This paper presents the test configuration, RF conditioning history and first high power performance of this cavity.

  • 48.
    Li, Han
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Goryashko, Vitaliy
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Bhattacharyya, Anirban
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Santiago-Kern, Rocio
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Hermansson, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Olry, Guillaume
    IPN Orsay, France.
    Niclas, Gandolfo
    IPN Orsay, France.
    RF test of ESS superconducting spoke cavities at Uppsala University2016In: Proceedings of  IPAC2016, 2016, p. 791-794Conference paper (Other academic)
    Abstract [en]

    The European Spallation Source (ESS) is an accelerator-driven neutron spallation source built in Sweden. It will deliver the first protons to a rotating tungsten target by 2019 and will reach the full 5 MW average beam power in the following years. The superconducting Spoke cavities are considered compact structures at low frequencies and having an excellent RF performance in both low and medium velocity regimes, therefore ESS will include a total of 26 double-spoke cavities. The testing of the double-spoke prototype cavity at high power has been conceded to Uppsala University, Sweden, where the Facility for Research Instrumentation and Accelerator development (FREIA) has been equipped with superconducting cavity test facility.

        A bare spoke cavity has been tested at the FREIA Laboratory with a self-exited loop at low power level to confirm its vertical test performance at IPNO. Similar test results as IPNO's previous test were obtained with FREIA system. In this paper we present the methods and preliminary study results of the cavity performance.

  • 49.
    Li, Han
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Jobs, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Gajewski, Konrad
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Santiago Kern, Rocio
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Hermansson, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    ESS Spoke Cavity Conditioning at FREIA2017In: Proceedings of IPAC2017, 2017, p. 1074-1076Conference paper (Other academic)
    Abstract [en]

    The first ESS double spoke cavity installed with RF power coupler was tested in the HNOSS cryostat at the FREIA Laboratory. Power coupler and cavity conditioning have been optimized in order to reach high efficiency and high availability by reducing the time and effort of the overall conditioning process. Meanwhile, an optimal procedure for ESS conditioning is studied. This paper presents the study result and experience of the RF conditioning procedure for the first ESS double spoke cavity.

  • 50.
    Li, Han
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Jobs, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Santiago Kern, Rocio
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Goryashko, Vitaliy A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Hermansson, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Bhattacharyya, Anirban
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Lofnes, Tor
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Gajewski, Konrad
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Fransson, Kjell
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    Characterization of a beta=0.5 double spoke cavity with a fixed power coupler2019In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 927, p. 63-69Article in journal (Refereed)
    Abstract [en]

    ESS, the European Spallation Source, will adopt a single family of double spoke cavities for accelerating the beam from the normal conducting section to the first family of the elliptical superconducting cavities. It will be the first double spoke cavities in the world to be commissioned for a high power proton accelerator. The first double spoke cavity for the ESS project was tested with high power in the HNOSS cryostat at Uppsala University. A pulse-mode test stand based on a self-excited loop was used in this test. The qualification of the cavity package involves a double-spoke superconducting cavity, a fixed fundamental power coupler, tuner, a low-level radiofrequency (LLRF) system and a high-power radiofrequency (RF) station. The test represents an important verification milestone before the module assembly. This cavity had unfortunately a high dynamic loss of 12W @ 9 MV/m, where potential causes for such a high value have been studied and corresponding suggestions are listed. This paper presents the test configuration, RF conditioning history, first high power performance and experience of this cavity package.

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