Abstract
The mean primary nuclear charges of fragments from thermal neutron fission of U235 as a function of initial mass in the range 88–105 have been determined from theK-ray energy spectra of the light fragments.K- rays were registered with an argon-methane filled proportional counter in coincidence with the pulses from a pair of semiconductor detectors for complementary fission fragments. The deviation of the mean primary charge of the fragments from the “unchanged charge density” value as compared to the density of the parent nucleus U236 was found to be 0.54±0.14 charge units independent of mass in the range 88–105. No closed shell effect on the mean primary charge was found.
Within about 10−9 sec after fission aK-X ray yield of 0.057±0.012 per fission in the light fragment group was measured. The yields are nearly independant of mass in the range 88–95 corresponding to a value of 0.04 per fragment and increase up to 0.09 in the mass range 95–104, the relative accuracy being 3 to 4%.
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The author likes to thank Prof. H.Maier-Leibnitz and Dr. P.Armbruster for suggesting this work and helpful comments. Thanks are also due to Drs. H. J.Specht and H.Vonach for their active interest and valuable discussions. I am indebted to Dr.Koester and the staff of the FRM for support of this experiment. The data analysis was performed on the TR 4 computer of the Leibniz-Rechenzentrum der Bayerischen Akademie der Wissenschaften.
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Reisdorf, W. Division of nuclear charge in the thermal neutron fission of U235 . Z. Physik 209, 77–92 (1968). https://doi.org/10.1007/BF01379793
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DOI: https://doi.org/10.1007/BF01379793