Time-of-flight calibration of a Li-6 glass epithermal neutron detector

The curing of Portland cement concrete involves the conversion of water fro m a free to a bound state. The process can be monitored nondestructively by measuring the shift in the neutron energy spectrum in the epithermal range (0.025-1 eV). A tuned array of Li-6 glass detectors has been constructed w ith varying efficiencies over the epithermal energy range. To determine the efficiency of each detector as a function of neutron energy, it is necessa ry to calibrate it against a reference neutron spectrum. This was accomplis hed using a time-of-flight approach with a pulsed neutron beam produced at the Gaerttner LINAC Laboratory at Rensselaer Polytechnic Institute. With a neutron flight path of 25 m it was possible to determine the neutron detect or efficiencies to an energy resolution of 11 mu eV. The data showed good a greement with the detector design calculations. (C) 2000 Published by Elsev ier Science Ltd.