Measurement of the ²³⁴U(n,f) cross section in the energy range between 14.8 and 17.8 MeV using Micromegas detectors

¹ Department of Physics, National Technical University of Athens, Zografou campus, 15780 Athens, Greece.
² European Organization of Nuclear Research (CERN), Geneva, Switzerland.
³ Department of Physics, University of Ioannina, 45110 Ioannina, Greece.
⁴ Tandem Accelerator Laboratory, Institute of Nuclear Physics, N.C.S.R. "Demokritos", Aghia Paraskevi, 15310 Athens, Greece.

^* Current Address: Institute of Nuclear and Radiological Sciences, Energy, Technology & Safety, N.C.S.R. "Demokritos", Aghia Paraskevi, 15310 Athens, Greece (email: a.kalamara@ipta.demokritos.gr).

Published online: 30 September 2020

Abstract

The ²³⁴U(n,f) reaction cross section was measured for three neutron energies 14.8, 16.5 and 17.8 MeV, relative to the²³⁸U(n,f) reference reaction. The in-beam measurements were carried out by using a set-up based on Micromegas detectors, while the quasi-monoenergetic neutron beams were produced by means of the ³H(d,n)⁴He reaction at the 5.5MV Tandem T11/25 Accelerator Laboratory of the National Center for Scientific Research "Demokritos" in Athens (Greece). Additionaly, α-spectroscopy measurements were performed in order to determine the active mass of the samples and the corresponding impurities. In order to estimate the fission-fragment detection efficiency, Monte Carlo simulations were carried out using the GEF and FLUKA codes. Furthermore, simulations were also performed by coupling the NeuSDesc and MCNP5 codes for the determination of the neutron energy distribution in all the irradiated samples and the results were used in order to correct for the contribution of low energy parasitic neutrons in the fission yield. The final cross section data are presented, along with the methodology adopted for the treatment of the parasitic neutrons.