| Autor: |
Maier-Leibnitz, H., Schmitt, H. W., Armbruster, P. |
| Jazyk: |
angličtina |
| Rok vydání: |
1965 |
| Předmět: |
|
| Zdroj: |
Jülich : Kernforschungsanlage Jülich, Verlag, Berichte der Kernforschungsanlage Jülich 331, 19 p. (1965). |
| Popis: |
The average number and energy of gamma-rays emitted as a function of fragment mass in $U^{235}$ thermal-neutron-induced fission have been measured. A three-parameter correlation experiment was performed in which two silicon surface barrier detectors were used to measure the fission product energies, and a 5-in-diam., 4-in-thick NaI(Tl) scintillation crystal was used to measure the gamma-ray energies. Extreme care was taken in the experimental arrangement to avoid counting direct fission neutrons, scattered gamma-rays and neutrons, and other false events. Data were recorded event-by-event in a system similar to that used in previous energy correlation experiments at Oak Ridge, and were analysed according to a "weighting method" proposed by Maier-Leibnitz. The total number and energy of the gamma-rays for both fragments as a function of mass ratio were obtained directly. The number and energy of gamma-rays for individual fragment masses were determined by making use of the variation in laboratory angular distribution and energy of the gamma-rays emitted from moving fragments. In particular, the 0° to 180° ratio of the number of gamma-rays from a moving source emitting isotropically in its centre-of-mass system is proportional to 1 + 2 x 2v/c; similariy the 0° to 180° ratio in total gamma energy is proportional to 1 + 2 x 3v/c. Thus by comparing appropriate ratlos in the analysis for light and heavy fragments moving towards or away from the gamma-ray detector, one obtains these quantities as a function of individual fragment mass. Results of preliminary analyses show interesting similarities in behaviour to those for neutrons. Both the total energy and average quantum energy of gamma-rays are essentially constant over most of the rangeof mass ratios; however a broad minimum is observed for the total energy in the region where MH $\thicksim$ 130, i. e. where $Z_{H}$ $\thicksim$ 50 or $N_{H}$ $\thicksim$ 82. An increase is observed in the total energy as the mass ratio approaches unity. The number and energy of gamma-rays emitted from individual fragments is observed to increase in both fragment groups and shows similar mass dependence, as has been observed for prompt neutrons. The average quantumenergy in the mass range of closed shells seems to be higher. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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