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Current pulse characteristics and gamma-noise frequency spectrum measurements for a neutron fission counter

Conference ·
OSTI ID:7347238
The pulse characteristics from neutron interactions in a fission counter (99.4 percent enriched /sup 235/U) were modeled for practical ranges of counter variables. The gamma-noise spectra of the counter were measured for these same ranges of counter variables so that the effects of the variables on both the neutron pulse characteristics and the gamma-noise spectra could be determined. The proper selection of counter variables will yield the highest practicable ratio of the neutron-induced signal amplitude to gamma-noise background. This optimization is required so that the counter can have a sensitivity of approximately 10 counts sec/sup -1/ (nv(th))/sup -1/ while exposed to a gamma dose rate of 10/sup 4/ to 10/sup 6/ R/hr. Such a counter is required for ex-vessel, low level, flux monitors in liquid-metal fast breeder reactors. New results obtained from this study include a determination of the effects of the fission counter electrode-to-ground capacitance, electron collection time, and the time constant of the electrode capacitance and preamplifier input resistance on the neutron-induced current pulse and the current pulse frequency spectrum. The effects of the electron collection time and electron capacitance-preamplifier resistance time constant on the magnitude of the gamma-noise spectra were also determined.
Research Organization:
Oak Ridge National Lab., Tenn. (USA)
DOE Contract Number:
W-7405-ENG-26
OSTI ID:
7347238
Report Number(s):
CONF-761006-4
Country of Publication:
United States
Language:
English