Accession Number : AD0801007

Title :   DELAYED GAMMA RAYS FROM FISSION.

Descriptive Note : Technical rept. for 1 Aug 65- 31 Jul 66,

Corporate Author : GENERAL DYNAMICS SAN DIEGO CA GENERAL ATOMIC DIV

Personal Author(s) : Walton, R. B. ; Sund, R. E.

Report Date : OCT 1966

Pagination or Media Count : 1

Abstract : Measurements of the energy spectrum of delayed gamma rays from the neutron fission of Pu239 and U235 were performed with a NaI detector at a number of time intervals between 2 and 80 microsec. The data showed three new prominent gamma rays with energies of 205, 390, and 1330 keV; two unresolved gamma rays having energies of approximately 110 keV; and the six gamma rays with energies of 260, 460, 720, 850, 910, and 1250 keV which were observed in previous studies for t > 50 microsec after fission. Absolute intensities of the new gamma rays were obtained using the normalization factor derived from the relative intensities of the last six gamma rays and their previously determined absolute intensities. The 205-, 390-, and 1330-keV gamma rays probably result from the cascade decay of a single isomer which has a half life of 3.4 + or - microsec and fission yields of 1.30 + or - 0.32 and 0.63 + or - 0.21 percent per fission of Pu239 and U235, respectively. Half lives and yields were also obtained for the two 110-keV gamma rays, but the results are tentative because of uncertainties in the data. The fission yields, cascade gamma rays, and half lives of the isomers responsible for early delayed gamma rays from U235 (n,F) Pu239 (n,F) have been summarized and total intensities and energy emission rates of gamma rays with energies greater than 140 keV have been presented as a function of time after fission over the range from 2 microsec to 25 msec. (Author)

Descriptors :   (*GAMMA RAYS, FISSION), NEUTRON REACTIONS, URANIUM, PLUTONIUM, HALF LIFE, NUCLEAR ISOMERS, EMISSIVITY.

Subject Categories : Nuclear Physics & Elementary Particle Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE