THE DEVELOPMENT OF THE SILICON-JUNCTION FAST-NEUTRON DOSIMETER FOR APPLICATION IN THE RADIATION-EFFECTS TESTING RANGE. Final Summary Report, June 1, 1961 to September 30, 1962

Experimental silicon-junction fast-neutron dosimeters were prepared with crystal type, base width, surface work damage, and a process modification to increase initial charge-carrier lifetime as variable parameters. Exarnination of the preirradiation characteristics of the devices revealed several unexpected effects related to the material and process variables. To accurately determine the neutron exposure of the experimental dosimeters, a complete independent calibration was made of the flux spectrum of the reactor at the core position used in the irradiations. Six fission foils and threshold detectors with threshold energies from 4 kev to 5.9 Mev were used. In/sup 115/ foils and S/sup 32/ pellets were included with the experimental dosimeters in each of the irradiations. The narrower base devices were shown to be much less sensitive to fastneutron irradiation than the wider base devices. Although the sensitivity of the device to irradiation was not linear, the nonlinearity was generally less than 20% from 10/sup 12/ to at least 10/sup 19/ nvt. It was observed that neither surface treatment nor lifetime retention process had a significant effect on the sensitivity of the devices. (auth)