Accession Number : AD0673108

Title :   PLUTONIUM BERYLLIUM NEUTRON SOURCE AS A SECONDARY CALIBRATION STANDARD,

Corporate Author : BALLISTIC RESEARCH LABS ABERDEEN PROVING GROUND MD

Personal Author(s) : Devanney,John A.

Report Date : JUN 1968

Pagination or Media Count : 36

Abstract : Plutonium-Beryllium (Pu-Be) neutron sources are calibrated with respect to total output, using a manganese-sulfate bath. When such sources are used as a point isotropic, secondary standard, inaccuracies occur due to the following reasons: (1) The neutron output is not isotropic, (2) the neutron output increases with time due to the build-up of Americium-241, resulting from the impurity of Plutonium-241, (3) the output spectrum is continuous from approximately 0.5 MeV to 10 MeV, (4) gamma rays exceed the number of neutrons emitted from the source. This report (1) presents the angular distribution of the neutron output of an 80 gram (4.81 curie) Plutonium-Beryllium neutron source, (2) shows that the increase in neutron output, due to the build-up of Americium-241 is 5.3 percent for a period of 43 months, (3) presents the neutron and gamma ray spectral distribution and intensity, (4) shows a neutron to gamma ray intensity ratio of 0.61:1 and a neutron to gamma ray dose (first collision-rads tissue) ratio of 9.36:1, (5) shows that a correction factor of 6.6 percent is required when the source is used as a point isotropic source of neutrons. (Author)

Descriptors :   (*NEUTRONS, SOURCES), PLUTONIUM ALLOYS, BERYLLIUM ALLOYS, STANDARDS, NEUTRON SPECTRUM, AMERICIUM, GAMMA RAY SPECTRA, DOSE RATE, NUCLEAR RADIATION SPECTROMETERS, PULSE DISCRIMINATORS, NEUTRON FLUX

Subject Categories : Nuclear Instrumentation

Distribution Statement : APPROVED FOR PUBLIC RELEASE