A neutron spectrometer that acquires and unfolds data in the field has been developed for use in the energy range from 1 to 20 MeV. The system includes an NE213 organic scintillation detector, automatic gain stabilization, automatically stabilized pulseshape discrimination, an LSl-11 microprocessor for control and data reduction, and a multichannel analyzer for data acquisition. The system, with the exception of the multichannel analyzer, is mounted in a suitcase 47 by 66 by 23.5 cm. The mass is 23.5 kg.

An extension of the methods of Lindhard et at. was used to calculate the total displacement function n/sub ij/(E) for a number of diatomic materials, where n/sub ij/(E) is defined to be the average number of atoms of type j which are displaced from their sites in a displacement cascade initiated by a PKA of type i and energy E. From the n/sub ij/(E) one can calculate the fraction n/sub ij/(E) of the displacements produced by a type i PKA with energy E which are of type j. Values of the n/sub ij/ for MgO, CaO, Al/sub 2/O/sub 3/, and TaO are presented. It is shown that for diatomic materials with mass ratios reasonably near one (e.g., MgO, Al/sub 2/O/sub 3/) and equal displacement thresholds for the two species the n/sub ij/ become independent of the PKA type i at energies only a few times threshold. However, for larger mass ratios the n/sub ij/ do not become independent of i until much larger, energies are reached - e.g. > 10/sup 5/ eV for TaO. In addition, it is found that the n/sub ij/ depend sensitively on the displacement thresholds, with very dramatic charges occuring when the two thresholds become significantly …

Thirty-one neutron cross sections have been extended to 44 MeV for dosimetry applications at high energy accelerator sources. Integral testing in Be(d,n) fields at E/sub d/ = 14, 16, and 40 MeV shows that 22 cross sections are accurate to within +- 10%. An example of routine flux-spectral unfolding and damage analysis is shown with an error analysis. Cross section needs are discussed.