Calibration of the TFTR neutron activation system

Abstract

Neutron generators, both D-D and D-T, have been used to calibrate the TFTR neutron activation (NA) system for point sources located within the tokamak. The foils used were In for D-D neutrons and Cu, Al, and 238U for D-T neutrons. Delayed neutrons following fission were counted when using 238U foils, 336-keV γ rays from 115In(n,n′) 115m In reactions, annihilation radiation from 62Cu following the 63Cu(n,2n)62Cu reaction, and 1368- and 2754-keV γ rays from the 27Al(n,α)24Na reaction. Large effects caused by source anisotropy and local machine structure were observed. These effects and the attempts to accommodate them in the data analysis will be described.