George F. Auchampaugh

The time resolution of bismuth germanate scintillation detectors

Abstract The time resolution of a bismuth germanate scintillation detector was measured as a function of γ-ray energy from 1 MeV to 24 MeV. The measured time resolution of the 60 Co cascade is (2.1±0.2)ns. The time resolution improves at higher γ-ray energies and is (890±60) ps at around 20 MeV.

A high-energy gamma-ray detector system for fast neutron-induced reactions

Abstract We have developed a gamma-ray detector system which is used in conjunction with a pulsed spallation neutron source to study fast neutron induced reactions. The detector system consists of five 7.6− × 7.6-cm bismuth germanate crystals that span an angular range from 45° to 140° in the reaction plane. The sample is located 7.2 m from the neutron-production target. With this apparatus it is possible to simultaneously measure the excitation functions and angular distributions of reaction gamma rays in the neutron energy range from 1 to 100 MeV. Results on the 12 C(n,n′ γ = 4.44 MeV) and 40 Ca(n, γ 0 ) reactions show the unique capabilities of this system.

Signal-to-background ratio for neutron production between 10 and 14 MeV by the reactions 3H(p,n)3He, 1H(t,n)3He, and 2H(d,n)3He☆

Abstract The monochromaticity of a “single line” neutron source is of utmost importance whenever secondary neutron yields over a wide energy range must be measured. Among the neutron sources considered, 3H(p,n)3He is best if a suitable beam stop is used, for example, 28Si or 28Ni. Tatalum and gold given much larger backgrounds.. Neutron emission spectra from the hydrogen gases and from various beam stops have been measured between 10 and 14 MeV and the signal-to-noise ratios of the neutron production have been determined as a function of the gas pressure. In addition, the 0° break-up cross sections for p on T and d on D were obtained.

A cryogenic ionization chamber for high-resolution fission cross-section measurements☆

Abstract This paper describes a multiple-plate gas ionization chamber designed for cross-section measurements of neutron-induced fission in strongly radioactive nuclei. The requirements of high resolution are discussed, in particular the need for cooling the sample to reduce Doppler broadening, and the selection of the gas mixtures that will enable fast counting at a low temperature. The observed gain in resolution with cooled samples is in good agreement with theoretical predictions.

Nuclear data needs for the space exploration initiative

On July 20, 1989, the President of the United States announced a new direction for the U.S. Space Program. The new Space Exploration Initiative (SEI) is intended to emplace a permanent base on the Lunar surface and a manned outpost on the Mars surface by 2019. In order to achieve this ambitious challenge, new, innovative and robust technologies will have to be developed to support crew operations. Nuclear power and propulsion have been recognized as technologies that are at least mission enhancing and, in some scenarios, mission enabling. Because of the extreme operating conditions present in a nuclear rocket core, accurate modeling of the rocket will require cross section data sets which do not currently exist.