A New Measurement of the 6Li(n,{\alpha})t Cross Section at MeV Energies Using a Fission Chamber and 6Li Scintillators

TL;DR

This study presents a new measurement of the $^6$Li(n,$ extalpha$)t cross section across a broad energy range using innovative scintillator detectors and a fission chamber, revealing discrepancies with existing data at higher energies.

Contribution

It introduces a novel experimental setup combining a fission chamber with $^6$Li scintillators for precise cross section measurements from 245 keV to 10 MeV.

Findings

Measurements agree with previous data except at 4.2 and 6.5 MeV resonances.

Discrepancies above 2 MeV likely due to neutron transport modeling issues.

Simulations help reconcile some differences with existing evaluations.

Abstract

A new measurement is presented of the $^6$Li(n,$\alpha$)t cross section from 245 keV to 10 MeV using a $^{252}$Cf fission chamber with $^6$LiI(Eu) and Cs$_2$LiYCl$_6$:Ce (CLYC) scintillators which act as both target and detector. Neutron energies are determined from the time of flight (TOF) method using the signals from spontaneous fission and reaction product recoil. Simulations of neutron downscatter in the crystals and fission chamber bring $^6$Li(n,$\alpha$)t cross section values measured with the $^6$LiI(Eu) into agreement with previous experiments and evaluations, except for two resonances at 4.2 and 6.5 MeV introduced by ENDF/B-VII.1. Suspected neutron transport modeling issues cause the cross section values obtained with CLYC to be discrepant above 2 MeV.