Prompt Gamma Rays Emitted in the Thermal-Neutron-Induced Fission of
- 1 September 1972
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review C
- Vol. 6 (3), 1023-1039
- https://doi.org/10.1103/physrevc.6.1023
Abstract
The average number and average energy of rays emitted within ∼5 nsec after fission have been determined as functions of fragment mass and as functions of fragment mass and total kinetic energy in two-dimensional representations. In a four-parameter experiment, energies of coincident pairs of fission fragments were measured with surface-barrier detectors and -ray energies were measured with a large NaI(Tl) detector, which was located 89 cm from a thin target and positioned coaxially with the fragment detectors. The time difference between detection of a fission fragment and a ray was measured to allow time-of-flight discrimination against fission neutrons. The -ray data were analyzed with a "weighting method" proposed by Maier-Leibnitz to deduce average numbers and energies of rays from measured pulse heights. The Doppler shift in the laboratory angular distribution of emission was utilized to obtain the number and energy of rays as functions of single fragment mass. The results, for both average number and average energy as functions of single fragment mass, are characterized by a sawtooth behavior similar to that which is well known for neutron emission. The over-all average number and energy of rays emitted per fission were found to be 6.51 ± 0.3 and 6.43 ± 0.3 MeV, respectively, giving an average photon energy of 0.99 ± 0.07 MeV.
Keywords
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