Charge distribution for the photofission of U238 with 20-MeV bremsstrahlung

D. De Frenne, H. Thierens, E. Jacobs, P. De Gelder, A. De Clercq, P. D'hondt, and A. J. Deruytter
Phys. Rev. C 21, 629 – Published 1 February 1980
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Abstract

Fractional independent or cumulative chain yields of 35 fission products were determined for the photofission of U238 with 20-MeV bremsstrahlung, using direct γ spectrometry of irradiated uranium samples, γ-ray spectrometry of fission product catcher foils, and chemical sparation techniques. For the mass chains 131-136 the width parameter c of the charge distribution was obtained. An average value of 0.93 ± 0.06 was deduced for c. A comparison of this c value with the results for other low-energy fissioning systems indicates that the width of the charge distribution is practically independent of the excitation energy of the compound nucleus. Using the average c value, the most probable charges Zp (20 MeV) were calculated for 8 light and 12 heavy mass chains. A comparison of the deduced Zp (20 MeV) behavior with the expectations of the unchanged charge density hypothesis shows the higher charge-to-mass ratio of the light fragments compared to the heavy ones and the influence of the closed 50-proton shell on the charge distribution. The Zp (20 MeV) values determined are very well reproduced by the empirical relation of Nethaway except in the vicinity of the Z=50 line.

NUCLEAR REACTIONS, FISSION U238(γ,F), Eγmax=20 MeV; measured: fragment γ-ray spectra; deduced: charge distributions, width and most probable charges.

  • Received 27 August 1979

DOI:https://doi.org/10.1103/PhysRevC.21.629

©1980 American Physical Society

Authors & Affiliations

D. De Frenne, H. Thierens, E. Jacobs, P. De Gelder, A. De Clercq, P. D'hondt, and A. J. Deruytter

  • Nuclear Physics Laboratory, Proeftuinstraat 86, B-9000 Gent, Belgium

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Vol. 21, Iss. 2 — February 1980

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