Development of a Solid-State Neutron Detector for SNAP 10A
- North American Aviation, Inc., Canoga Park, CA (United States). Atomics International Div.
Electronic devices, primarily semiconductors, degrade in a nuclear radiation environment. In a reactor environment most of the damage is due to fast neutrons. The lithium hydride shield on SNAP 10A was designed to attenuate the fast neutron exposure at the instrument compartment to a tolerable level. To evaluate shield effectiveness fast neutron detectors were developed. Eight detectors were installed in the SNAP 10A FS-4 flight system. This report discusses the development and in-flight data of these detectors. Each detector consisted of a 2N697 transistor as the variable leg in a bridge circuit. The complete detector was 1-1/4 x 1-1/4 x 3/4 in., consumed 0.26 watts, and weighed less than 3 oz with wiring. The degradation of transistor gain was correlated to integrated fast neutron flux in ground tests. These ground test data were used to reduce flight data. During final qualification testing, it was found that the detectors were extremely gamma sensitive. For the comparatively low fast-neutron/gamma ratio in the SNAP 10A instrument compartment, the high gamma sensitivity decreased the detector's accuracy at mid-scale from about ±15% to accuracies ranging from ±35 to ±60%, depending on the fast neutron/gamma ratio. The data from the 43-day flight of the SNAP 10A FS-4 system indicated fast neutron fluxes (>0.1 Mev) ranging from 0.64 x 106 n/cm2-sec to 1.82 x 106 n/cm2-sec in the instrument compartment. The exposures integrated for 43 days ranged from 2.4 x 1012 to 6.8 x 1012 nvt. The exposures extrapolated for one year range from 2.0 x 1013 to 5.7 x 1013 nvt.
- Research Organization:
- North American Aviation, Inc., Canoga Park, CA (United States). Atomics International Div.
- Sponsoring Organization:
- US Atomic Energy Commission (AEC)
- DOE Contract Number:
- AT(11-1)-GEN-8
- NSA Number:
- NSA-20-020298
- OSTI ID:
- 4560459
- Report Number(s):
- NAA-SR--11762
- Country of Publication:
- United States
- Language:
- English
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