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Title: Neutron spectrum measurements for radiation protection purposes

Technical Report ·
DOI:https://doi.org/10.2172/6853182· OSTI ID:6853182

The energy spectra of low-intensity neutron sources used for calibrating personnel neutron dose-rate meters and dosimeters and for characterizing the neutron fields to which personnel are exposed were measured. Several detector-analyzer systems that will measure in the energy range 50 keV to 20 MeV at intensities from 10/sup -1/ to 10/sup 5/ n/cm/sup 2/-s are described. The systems include NE213 and stilbene organic scintillators as well as H/sub 2/, /sup 3/He, and CH/sub 4/ proportional counters. Also described are pulse-height analysis and pulse-shape discrimination systems. An unfolding code, NUTSPEC, reduces the pulse-height data to an absolute differential neutron flux phi(E) for the above detectors. The code uses a derivative unfolding method for the scintillation detectors, and for the proportional counters it calculates a response matrix and uses an iterative unfolding method to determine phi(E). The unfolded flux distribution combined with published conversion factors produces differential neutron dose-equivalent and kerma rates. Spectral segments obtained with different detectors from several measurements merge into a single differential flux spectrum over the range 50 keV to 20 MeV, together with the corresponding differential kerma and neutron dose-equivalent distributions. Also reported are spectrum measurements near /sup 252/Cf and /sup 238/PuBe sources with various moderators.

Research Organization:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
6853182
Report Number(s):
UCRL-52415; TRN: 78-014826
Country of Publication:
United States
Language:
English