Measurement of the ²³⁶U(n,f) cross section at fast neutron energies with Micromegas Detectors

¹ CEA, DEN, DER/SPRC/LEPh, Cadarache, F-13108 Saint Paul Lez Durance, France
² National Technical University of Athens, Greece
³ European Organization for Nuclear Research (CERN), Switzerland
⁴ National Centre for Scientific Research 'Demokritos', Greece
⁵ University of Ioannina, Greece

^* e-mail: maria.diakaki@cea.fr
^** e-mail: veatriki.michalopoulou@cern.ch

Published online: 30 September 2020

Abstract

In the present work, the measurement of the ²³⁶U(n,f) cross section was performed, with reference to the ²³⁸U(n,f) reaction. The measurements took place at the neutron beam facility of the National Centre for Scientific Research "Demokritos" (Greece) and the quasi-monoenergetic neutron beams were produced via the ²H(d,n)³He reaction in the energy range 4–10 MeV. Five actinide targets (two ²³⁶U, two ²³⁸U and one ²³⁵U) and the corresponding Micromegas detectors for the detection of the fission fragments were used. Detailed Monte Carlo simulations were performed, on one hand for the study of the neutron flux and energy distribution at the position of each target, and on the other hand for the study of the energy deposition of the fission fragments in the active volume of the detector. The mass and homogeneity of the actinide targets were experimentally determined via alpha spectroscopy and the Rutherford Backscattering Spectrometry, respectively. The experimental procedure, the analysis, the methodology implemented to correct for the presence of parasitic neutrons and the cross section results will be presented and discussed.