Correlation of Radiation Damage in Solid State Devices to Neutron Spectral Characteristics

Neutron spectral characteristics from the White Sands Missile Range Fast Burst Reactor (the FBR-II) has been studied with great detail the past several years. Results from these investigations have been directed primarily toward the measurement of neutron spectra under free-field and selected perturbed environments along with their respective spectral parameters such as spectral index and average neutron energy greater than 10 KeV. The present investigation consists of the exposure of groups of 2N2222A transistors to the neutron environments previously studied and the correlation of the device damage data with the neutron spectral parameters. Three of the test configurations were essentially free-field neutron environments. The neutron spectra and spectral parameters were identical for each of the three tests leading to the speculation that identical damages from the 2N2222A's should be observed. The measured damage from these devices corroborated such a prediction. Conversely, the neutron spectra and spectral parameters for the remaining two tests indicated highly perturbed neutron environments compared to the free-field measurements and, as such, would lead one to expect device damage different from free-field. However, damage of the devices revealed an amount of radiation damage essentially equivalent to that of the free-field environment.