Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Measurements of Neutron-induced Nuclear Reactions for More Precise Standard Cross Sections and Correlated Fission Properties
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.ORCID iD: 0000-0002-1705-4086
2017 (English)Doctoral thesis, monograph (Other academic)
Abstract [en]

It is difficult to underestimate the importance of neutron cross section standards in the nuclear data field. Accurate and precise standards are prerequisites for measuring neutron cross sections. Two different projects are presented here with the aim of improving on neutron standards.

A simulation study was performed for an experiment intended to measure the cross sections of H(n,n), 235U(n,f), and 238U(n,f) relative to each other. It gave the first estimates of the performance of the experimental setup. Its results have aided the development of the experimental setup by setting limits on the target and detector design.

A second neutron-standard project resulted in three measurements of 6Li(n,α)t relative to 235U(n,f). Each subsequent measurement improved upon the previous one and changed the experimental setup accordingly. Although, preliminary cross sections were agreeing well with evaluated data files in some energy intervals, the main goal to measure the cross section up to 3 MeV was not reached.

Mass yields and energy spectra are important outcomes of many fission experiments, but in low yield regions the uncertainties are still high even for recurrently studied nuclei. In order to understand the fission dynamics, one also needs correlated fission data. One particular important property is the distribution of excitation energy between the two nascent fission fragments. It is closely connected to the prompt emission of neutrons and γ’s and reveals information about how nucleons and energy are transferred within the fissioning nucleus.

By measuring both the pre and post neutron-emission fragment masses, the cumbrance of detecting neutrons directly is overcome. This is done using the fission spectrometer VERDI and the 2E-2v method. In this work I describe how both the spectrometer, the analysis method, and the calibration procedures have been further developed. Preliminary experimental data show the great potential of VERDI, but also areas that call for more attention. A previously overlooked consequence of a central assumption was found and a correction method is proposed that can correct previously obtained data as well.

The last part of this thesis concerns the efficiencies of the fission product extraction at the IGISOL facility. The methodology of the fission yield measurements at IGISOL are reliant on assumptions that have not been systematically investigated. The presented work is a first step of such an investigation that can also be used as a tool for optimising the setup for measurements of exotic nuclei. A simulation framework connecting three different simulation codes was developed to investigate the produced yield of fission products in a buffer gas. Several different variants of the setup were simulated and the findings were generally accordant with previous estimates. A reasonable agreement between experimental data and the simulation results is demonstrated.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2017. , p. 142
Series
Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-2516 ; 131
Keyword [en]
Cross Section, Fission, Neutron-induced reactions, Simulation, VERDI
National Category
Subatomic Physics
Research subject
Physics with specialization in Applied Nuclear Physics
Identifiers
URN: urn:nbn:se:uu:diva-329953ISBN: 978-91-513-0085-6 (print)OAI: oai:DiVA.org:uu-329953DiVA, id: diva2:1144222
Public defence
2017-11-10, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2017-10-18 Created: 2017-09-25 Last updated: 2017-11-13

Open Access in DiVA

fulltext(4596 kB)111 downloads
File information
File name FULLTEXT01.pdfFile size 4596 kBChecksum SHA-512
7d78a70aa92a5a63457462c0a08ead9f52187acc7454dfa8200d05af90786620119024dc546afc0449aa68035e4661f825505c020810ca2e50281f9081ef2d64
Type fulltextMimetype application/pdf
Buy this publication >>

Search in DiVA

By author/editor
Jansson, Kaj
By organisation
Applied Nuclear Physics
Subatomic Physics

Search outside of DiVA

GoogleGoogle Scholar
Total: 111 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 335 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf