A technique for verifying the input response function of neutron time-of-flight scintillation detectors using cosmic rays

• Published in: Review of scientific instruments 2014-11, Vol.85 (11), p.11D633-11D633
• Main Authors: Bonura, M A, Ruiz, C L, Fehl, D L, Cooper, G W, Chandler, G, Hahn, K D, Nelson, A J, Styron, J D, Torres, J A
• Format: Article
• Language: English
• Subjects: BREMSSTRAHLUNG; CALIBRATION; COSMIC RADIATION; COUNTING RATES; INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; LINEAR ACCELERATORS; NEUTRON DETECTORS; PHOTOMULTIPLIERS; PULSES; RESPONSE FUNCTIONS; SANDIA NATIONAL LABORATORIES; SCINTILLATION COUNTERS; TIME-OF-FLIGHT METHOD
• ISSN: 0034-6748; 1089-7623
• DOI: 10.1063/1.4896958

An accurate interpretation of DD or DT fusion neutron time-of-flight (nTOF) signals from current mode detectors employed at the Z-facility at Sandia National Laboratories requires that the instrument response functions (IRF's) be deconvolved from the measured nTOF signals. A calibration facility that produces detectable sub-ns radiation pulses is typically used to measure the IRF of such detectors. This work, however, reports on a simple method that utilizes cosmic radiation to measure the IRF of nTOF detectors, operated in pulse-counting mode. The characterizing metrics reported here are the throughput delay and full-width-at-half-maximum. This simple approach yields consistent IRF results with the same detectors calibrated in 2007 at a LINAC bremsstrahlung accelerator (Idaho State University). In particular, the IRF metrics from these two approaches and their dependence on the photomultipliers bias agree to within a few per cent. This information may thus be used to verify if the IRF for a given nTOF detector employed at Z has changed since its original current-mode calibration and warrants re-measurement.