Type of Document Master's Thesis Author Leyland, Walter A URN etd-04262010-020346 Title A Bf3 Fast Neutron Dosimeter (Long Counter) Degree Master of Science Department Physics Advisory Committee
Advisor Name Title thesis, none found in Committee Chair Keywords
Date of Defense 1960-09-03 Availability restricted Abstract
A BF3 fast neutron dosimeter or long counter is constructed and calibrated for use with the Cockcroft-Walton accelerator and UTR-IO reactor at Virginia Polytechnic Institute. The counter consists of a paraffin cylinder 8 inches in diameter, having a BF3 proportional detector on the axis and a set of holes around the detector to improve the low energy response. External shields of paraffin, 3 inches thick, and boron-trioxide, 1/2 inch thick, enclose the paraffin cylinder. These shields serve to reduce the background effect and improve the high energy response.
Calibration of the counter is accomplished using as neutron sources: plutonium-berylliwn and the induced reactions H2(d,n)He3 and H3(d,n)He4. Long counter efficiencies for both a 1 inch and 1/2 inch BF) tube yield a flat response over the energy range, 2.5 to 4 Mev whereas an approximately 60% decrease in efficiency is observed for a 14.1 Mev neutron.
Count rate of long counter is expressed as a function of the incident neutron flux. Neutron fluxes, ranging from 0 to 1100 neutrons/cm2-seeond are monitored with the counter.
Filename Size Approximate Download Time (Hours:Minutes:Seconds)
28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access LD5655.V855_1960.L495.pdf 15.28 Mb 01:10:44 00:36:22 00:31:50 00:15:55 00:01:21next to an author's name indicates that all files or directories associated with their ETD are accessible from the Virginia Tech campus network only.
If you have questions or technical problems, please Contact DLA.