Neutron Dosimetry Standard.
Abstract
The neutron spectrometry program described in this report was carried out in support of a set of draft ASTM standards prescribing a standard method of measuring neutron spectra and characterizing the spectra in terms of their effectiveness in producing radiation damage in silicon. The neutron fluence is characterized in terms of phi(eq), the number of near-1-MeV neutrons required to produce the same radiation damage, and the spectral shape in terms of phi(eq)/phi, the equivalent 1-MeV fluence per unit fluence of neutrons above 0.01 MeV. Since there are no useable thresholds between 0.01 and 0.5 MeV, the spectrum is, to a large extent, indeterminate below 1 MeV. However, it was found that reactor spectra can be parameterized by fitting a 1/E tail to a fission or GODIVA-core spectrum, the fitting point being determined by the threshold-foil data. In this way, the uncertainty interval can be reduced to yield accuracies in phi(eq)/phi and phi(eq) of 5 and 10%, respectively. The program included an evaluation of many candidate methods of specifying a neutron field, a selection of the most suitable method (threshold-foil spectrometry), a measurement of three different spectra, a comparison of the measurements with 'known' spectra to determine the accuracy of the method, a comparison of threshold-foil measurements carried out by two different laboratories to evaluate the precision of the method, a variational study to determine the factors that most sensitively impact the accuracy, and folding the spectra in with a recently claculated silicon radiation damage function D(E) to express the accuracy in terms of a single parameter phi(eq) or phi(eq)/phi.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 15, 1977
- Accession Number
- ADA042276
Entities
People
- V. V. Verbinski