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RADIOCHEMICAL STUDY OF THE RARE-EARTH ELEMENT YIELD IN THE CASE OF THE PHOTOFISSION OF URANIUM-238 (in Russian)

Journal Article · · At. Energ. (USSR)
OSTI ID:4130716
In the photofission of elements heavier than Th, at low excitation levels, heavy and light fragments are obtained; the light group contains the rare earths. In view of the limited amount of information on the photofission of heavy elements, the yields of fragments obtained during the photofission of U/sup 238/ were determined because in that case the indeterminancy of the mass and the charge of the fissioning nucleus is avoided. The maximum energy of the bremsstrahlung at 14 Mev was chosen for the determination of the mass distribution of the fission fragments. The hot-pressed U oxide specimens were irradiated in the betatron of the Leningrad Technical Institute at a maximum electron energy of 15 Mev. The relative yields of La/sup 141/, Ce/sup 143/, Pr/ sup 145/, Nd/sup 147/, Nd/sup 149/, Pm/sup 151/, Y/sup 93/, Ru/sup 103/, Ru/sup 105/, Ag/sup 111/, and Ag/sup 113/ were determined, using Ce/sup 113/ as the standard fission fragment for calibration. The Pm/sup 149//Pm/sup 151/ and the Nd/sup 147/ Nd/sup 149/ ratios were found to be 2.07 plus or minus 0.08 and 1.99 plus or minus 0.06, respectively. The data allowed a curve describing the correlation between the fission fragment yield and the mass number to be plotted. No data were obtained in the mass number ranges from 94 to 103 and 132 to 141. It was found that the masses at the high and low peaks of the groups are reduced and the yields of the symmetric fragments are increased. It may be assumed that the yields of strongly asymmetric masses increase with increasing excitation energy. (TTT)
Research Organization:
Originating Research Org. not identified
NSA Number:
NSA-18-004594
OSTI ID:
4130716
Journal Information:
At. Energ. (USSR), Journal Name: At. Energ. (USSR) Vol. Vol: 15
Country of Publication:
Country unknown/Code not available
Language:
Russian