Design and performance of a compact subthermal neutron source for an Electron Linear Accelerator

Abstract

We present the design, construction and performance of a compact subthermal neutron source to be operated at the Bariloche Electron LINAC. The design was based on the premise of keeping the moderator temperature stable at 77 K for at least seven hours without refilling liquid nitrogen. Two moderator materials in semi-cylindrical geometry were studied: polyethylene and mesitylene. The effective moderator volumes were optimized by Monte Carlo simulations. Experimental data and calculations corresponding to the neutron production as a function of the neutron energy for those materials at room temperature and at 77 K were compared. We observed that the rate of subthermal neutrons, compared to epithermal neutrons, increases up to five times for both moderators when they are cooled down.

Model for neutron total cross-section at low energies for nuclear grade graphite

“…The neutron transmission experiments were performed at the Bariloche electron linear accelerator (LINAC) facility (Argentina), and described in Refs. [2,33], so only a brief overview will be given here. A general scheme of the transmission experimental setup is shown in Fig.…”