Simultaneous Neutron Spectrum and Transistor-Damage Measurements in Diverse Neutron Fields: Validity of D sub Si (E sub n)

Abstract : This report contains a summary of intercalibration measurements carried out on four different reactors under various irradiation conditions. These reactors were the Northrop TRIGA, SANDIA SPR II and ACPR, and the Aberdeen APRF reactor. The intercalibration was carried out by (a) measuring neutron spectra for a variety of basic and modified ('filtered') reactor neutron fields with a standard threshold-foil-activation neutron spectrometry method, (b) folding in each spectrum phi(E) with the silicon damage function D(E) to obtain phi sub eq, the number of near-1 MeV neutrons required to produce the same damage, (c) irradiating a batch of 2N2222A transistors simultaneously with the neutron dosimetry stack and measuring the total damage D = K phi, and (d) dividing D = K phi by phi sub eq to obtain values of the damage coefficient K for the diverse neutron fields measured. This work is a continuation of a Defense Nuclear Agency (DNA) sponsored effort, initiated in 1974, in which several different spectra (WSMR FBR glory hole and leakage, and TRIGA leakage) were measured and variation studies carried out to determine the sensitivity of phi sub eq to the many possible sources of error. To make this report as complete as possible for the user, these previous results have been included as Appendix A. The culmination of this work was a set of ASTM draft standards (Appendix B) which were followed in detail, except for an important improvement recently developed by one of the authors of this report (VVV).