Gamma-ray Spectra Arising from Thermal-neutron Capture in Elements Found in Soils, Concretes, and Structural Materials


Book Description

Gamma-ray spectra arising from the capture of thermal neutrons are presented for iron, aluminum, copper, zinc, titanium, nickel, silicon, calcium, potassium, sodium, barium, chlorine, sulfur, and stainless steel. The spectral intensities in photons per 100 captures are presented as both individual lines and as sums of these lines over 0.5-MeV intervals which are intended for use in shielding calculations. The latter results have an estimated accuracy of plus or minus 15%, and include the contributions from both discrete and continuum gamma rays. Comparisons of these spectra are made with previously determined spectra, as well as with values reported in the Reactor Handbook, and considerable revision in the latter is concluded to be necessary. The present results do not go below 1 MeV, but when the relatively small contributions from energies less than 1 MeV are added to them, binding energy checks within plus or minus 5% are obtained. (Author).




Gamma-ray Spectra Arising from Fast-neutron Interactions in Elements Found in Soils, Concretes, and Structural Materials


Book Description

Experimental data are presented for the production of secondary gamma rays arising from the interaction of a fission-like spectrum of fast neutrons with oxygen, carbon, iron, aluminum, copper, zinc, titanium, nickel, silicon, calcium, potassium, sodium, barium, sulfur, and a stainless steel. These data are useful in evaluating the accuracy of (n, x gamma) cross-section sets. The data are differential in the gamma-ray energy from 1 MeV to approximately 6.5 MeV and are expressed as values for 4 pi times the average differential gamma-ray production cross section at 90 deg to the incident neutron beam for all neutrons in the beam lying above 1 MeV. These results are estimated to have an accuracy of plus or minus 30% and include the contribution from both discrete and continuum gamma rays. Very approximate experimental data are presented for gamma rays arising from resonance capture of neutrons from a 1/E energy spectrum in the energy range 10-200 keV. (Author).
















Scientific and Technical Aerospace Reports


Book Description

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.




NBS Special Publication


Book Description




Gamma-ray Spectra of Resonance Neutron Irradiated Earth Materials


Book Description

Clay mineral and soil samples were subjected to neutron activation analysis in order to identify and measure the abundances of trace elements having radionuclides with long half-lives. After exposure of cadmium-shielded samples to neutrons for a period of five days, the gamma radiation associated with the decay of the resulting radionuclides was observed using a high resolution Ga(Li) detector. Trace elements identified without prior chemical separation using the gross gamma-ray spectra included Fe, Zn, Ti, Ni Co, Cr, Sr, Ba, Ca, La, Eu, Tb, Hf, Ta, Th, and U. It should be possible to determine quantitatively the amount of each of these elements. This is a considerable improvement over the number of elements determined in soils previously by activation analysis without destructive chemical treatments. (Author).




Line and Continuum Gamma-ray Yields from Thermal-neutron Capture in 75 Elements


Book Description

The document presents the results of an analysis of thermal capture gamma-ray spectral data obtained at the MIT Thermal Capture Gamma-Ray Facility using a Ge(Li)-NaI spectrometer. This data has been previously analyzed to obtain the energies and intensities of the resolved lines from radiative neutron capture in 75 natural elements. In the present work, the spectral data was unfolded to remove the effect of the spectrometer response, and the total gamma-ray yield for both discrete lines and continuum, was determined. The method of analysis, described previously by Harper and Rasmussen, is briefly summarized. Also discussed are the binding energies producing a consistent set of values. A comparison of some of the present results with previous data is given. The capture gamma-ray energies and intensities are tabulated and the original gamma-ray spectra are shown for each element. The total gamma-ray yield data for each element has been written onto magnetic tape in the ENDF format to facilitate the use of this data by radiation transport codes. A description of the tape preparation procedure and the data formats employed are given. (Author).