1. Direct measurement of the branching ratioΓn/ΓfofU238in inelastic alpha scattering in the giant resonance region
- Author
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M. R. Yearian, P. J. Countryman, J. R. Calarco, K. van Bibber, and K. A. Griffioen
- Subjects
Nuclear reaction ,Physics ,Nuclear and High Energy Physics ,Fission ,Branching fraction ,Computer Science::Information Retrieval ,Nuclear Theory ,Alpha particle ,Inelastic scattering ,Giant resonance ,Neutron ,Atomic physics ,Nuclear Experiment ,Energy (signal processing) - Abstract
We have directly measured, for the first time, the neutron-fission branching ratio, {Gamma}{sub {ital n}}/{Gamma}{sub {ital f}}, of an actinide nucleus ({sup 238}U) excited in inelastic scattering as a function of excitation energy. This was accomplished using a {approx}4{pi} array of fission counters to separate fission neutrons from decay neutrons in the simultaneous coincidence experiments ({alpha},{alpha}{prime}{ital f}) and ({alpha},{alpha}{prime}{ital n{bar f}}). The measured branching ratio agrees well with previous photoneutron data. In a separate experiment, we have measured the angular distribution of alpha particles scattered from {sup 238}U in coincidence with fission decay ({alpha},{alpha}{prime}{ital f}). This provides us with an estimate of the cross section (in the fission channel) for exciting the isosca- lar giant monopole and giant quadrupole resonances. This estimate, combined with the {Gamma}{sub {ital n}}/{Gamma}{sub {ital f}} measurement, allows us to place bounds on the neutron-fission branching ratio for the isoscalar giant monopole and giant quadrupole resonances themselves.
- Published
- 1990
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