Emission of K x rays and division of nuclear charge in the spontaneous fission of 252Cf

Kapoor, S. S. ; Bowman, H. R. ; Thompson, S. G. (1965) Emission of K x rays and division of nuclear charge in the spontaneous fission of 252Cf Physical Review, 140 (5B). B1310-B1317. ISSN 0031-899X

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Official URL: http://prola.aps.org/abstract/PR/v140/i5B/pB1310_1

Related URL: http://dx.doi.org/10.1103/PhysRev.140.B1310


Measurements of the energies of the prompt K x rays emitted by the fragments in the spontaneous fission of 252Cf have been made which give information concerning the division of nuclear charge in fission. The kinetic energies of the pairs of fragments and the coincident K x rays emitted along the direction of fragment motion were recorded event by event, using a multiparameter analyzer. The energies of the fragments were measured by two semiconductor detectors, and the x-ray energies were measured with a lithium-drifted silicon detector operated at dry-ice temperature. The energy resolution of the x-ray detector as measured in terms of the full width at half-maximum of the 59.57-keV line of 241Am was 3.5 keV. The data were analyzed to obtain (a) the most probable charge versus the fragment mass, (b) the x ray yield per fragment versus the fragment mass and charge, and (c) the average half-life for x-ray emission versus the fragment mass and charge. The measured x-ray emission times and the variation of the x-ray yield per fragment with the fragment mass are found to be consistent with the view that these x rays are emitted as a result of the internal-conversion process during the de-excitation of the fragment nuclei. In the heavy group, the abrupt rise in the x-ray yield at fragment mass 144 appears to be connected with the onset of large stable nuclear deformations of fragment nuclei at neutron number about 88. The measured x-ray yield from the light-fragment group suggests that most of these nuclei make up a new region of deformation. The observed variation of the most probable charge with the fragment-mass ratio over a limited mass region is found to be very similar to that obtained in radiochemical studies of the thermal fission of 235U.

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Source:Copyright of this article belongs to American Physical Society.
ID Code:16913
Deposited On:16 Nov 2010 13:20
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