HIGH RESOLUTION MEASUREMENTS OF GAMMA RAYS FROM THERMAL AND RESONANCE NEUTRON CAPTURE IN [sup]117[/sup]n, [sup]118[/sup]Sn and [sup]120[/sup]Sn


Book Description

High resolution measurements of the gamma ray spectra from thermal and resonance neutron capture in 117Sn, 118Sn and 120Sn have been made with a lithium-drifted germanium detector. A beam of pure thermal neutrons was obtained by double reflection from inconel mirrors of a reactor beam from the Oak Ridge Research Reactor. A cadmium filtered reactor beam served as the source of resonance neutrons. Earlier measurements of the gamma rays from the isotopes of tin with a NaI spectrometer had demonstrated the value of using both thermal and resonance energy neutrons and the need for higher resolution of the gamma rays. The lithium-drifted germanium crystal was 2.6 cm2 in area by 7 mm thick and was furnished by R.J. Fox, ORNL. For high energy gamma rays (> H"2000 keV) the pair production process with the subsequent escape of both annihilation quanta is the predominant process. Above 4000 keV the resolution was 10-15 keV for runs of several days duration and the energies of the lines may be measured to ± 10 keV absolute and ± 5 keV relative. For low energy gamma rays (













Neutron Capture Gamma-Ray Spectroscopy


Book Description

The post World War II era witnessed a tremendous growth in the research carried out in neutron-induced reactions and especially in neutron capture y-ray studies. This growth was stimulated by the availability of neutron sources, such as reactors and accelerators, and by the development of high resolution y-ray and conversion electron detectors. Today the combination of high flux reactors and precise instrumentation has produced spectral data of exceptional quality, as the pages of these proceedings illustrate. The world-wide community of the practioners of the art of cap ture y-ray spectroscopy has met three times in the last decade: the first international symposium on this subject was held at Studsvik, Sweden in 1969, and the second at Petten, The Netherlands in 1974. A smaller meeting, of mostly u. S. and some European parti cipation, was held at Argonne National Laboratory in 1966. A perusal of the proceedings of these meetings shows the striking ad vances in this now mature field of physics over the last dozen years. Each meeting has seen a small but perceptible increase in the number of papers presented and the number of laboratories repre sented. More importantly, each meeting has documented the increasing impact of (n,y) reasearch, not only on other areas of basic physics, but also on commercial and medical applications of this technology. A total of 29 invited papers and 97 contributed papers were presented at this symposium.
















Database of Prompt Gamma Rays from Slow Neutron Capture for Elemental Analysis


Book Description

Neutron-capture prompt-gamma activation analysis (PGAA) is particularly valuable as a non-destructive nuclear method in the measurement of elements that do not form neutron capture products with delayed gamma ray emissions. Inaccurate and incomplete data have been a significant hindrance in the qualitative and quantitative analysis of complicated capture gamma spectra by means of PGAA. This database was produced to improve the quality and quantity of required data in order to make possible the reliable application of PGAA in fields such as materials science, geology, mining, archaeology, environment, food analysis and medicine. The database provides a variety of tables for all natural elements (from H to U) including the following data: isotopic composition, thermal radiative cross-section (total and partial), Westcott g-factors, energy of the gamma rays (prompt and delayed), decay mode, half-life and branching ratios. The CD-ROM included in this publication contains the database, the retrieval system and important electronic documents related to the project.--Publisher's description.