Developpement and optimisation of gamma-ray spectrometry techniques : control and reduction of the associated uncertainties
type: Dataset
description: In the frameworks of the neutronics calculation schemes improvement and qualification, this thesis consists of the conception, the optimization and the development of g-ray spectrometry techniques for the measurement of integral parameters, in the EOLE and MINERVE facilities. The work aims at correcting systematic errors and at controlling and reducing uncertainties on the measurement results. The achieved progresses allow a more precise comparison between calculations and experiments and a better knowledge of some nuclear data, especially integral capture and fission cross sections. Firstly, the former instrumentation - using an analog chain (2026 amplifier and PCA3 converter / analyser) - has been fully tested to estimate the experimental errors on the determination of neutronics parameters. This work shows a systematic bias up to 12% on the measurement of the power distribution scaling factor and up to 3% on the measurement of the axial buckling, due to the lack of pulse pile-up correction. Following a comparative study, these electronics have been replaced by a digital DSP2060 system with an adapted dead time correction. With the optimization of its parameters, a precision at better than 0.5% has been achieved until a 1.5'105 s-1 count rate. Consequently, this work allows new kinds of experiments, which could not have been done with a sufficient precision by the past. Secondly, the former methods applied to the treatment of measurement raw data and to the variance propagation, have been analysed and discussed. Different systematic errors, which were not taken into account by the past, are now corrected. They concern the influence of the activity decay on the dead time correction (about 2%), the true coincidence effect (about 5%) and the solid angle effect on the efficiency transfer corrections (about 8%). Besides, the description of more precise methods for the variance propagation leads to a 3 times better uncertainty on fundamental neutronics parameters - scal…
landing page: https://theses.hal.science/tel-00703303
identifier: NNT: 2006CLF21684
keyword: absorbants-neutroniques
keyword: actinides
keyword: cross-sections
keyword: fission-yields
keyword: formulaire-de-calcul
keyword: g-ray-spectrometry
keyword: half-lives
keyword: incertitudes
keyword: infoeu-reposemanticsdoctoralthesis
keyword: integral-measurements
keyword: mesures-integrales
keyword: neutron-absorbers
keyword: neutronics-calculation-schemes
keyword: periode-radioactive
keyword: physnuclphysics-physicsnuclear-theory-nucl-th
keyword: reaction-rates
keyword: rendements-de-fission
keyword: sections-efficaces
keyword: spectrometrie-g
keyword: taux-de-reaction
keyword: theses
keyword: uncertainties
issued: 2026-05-16T09:14:47.567945
modified: 2026-05-16T09:14:47.567953
language: fr
contact point: Organization
  fn: CCSD

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type: Agent

Developpement and optimisation of gamma-ray spectrometry techniques : control and reduction of the associated uncertainties
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format: HTML
access URL: https://theses.hal.science/tel-00703303
issued: 2026-05-16T09:14:47.695624
modified: 2026-05-16T09:14:47.492459