Abstract
On the basis of data obtained by the incomplete fusion reactions 7Li(43A MeV)+232Th and 14N(34A MeV)+197Au, the energy dependence of the variance (σ 2M ) of the fragment mass in fission of highly heated nuclei has been investigated for total excitation energies E *tot ranging from 50 up to 350 MeV. The dependence σ 2M E *tot shows some unexpected features when E *tot exceeds a value of about 70 MeV. After this value, the steady increase of σ 2M expected from its temperature dependence changes to some kind of plateau between 100 and 200 MeV. Further on, at E *tot in excess of about 250 MeV, the variance is found to increase again sharply. In order to analyze this behavior quantitatively, a dynamical stochastic model has been developed. The model employs the one-body dissipation mechanism and describes the decay of highly excited and rotating nuclei by fission and light-particle evaporation. It satisfactorily explains the measured prior-to-scission neutron multiplicities and the experimental mass variances up to E *tot ≅250 MeV, but the stochastic treatment does not reveal any increase in σ 2M at higher excitation energies in contradiction with the data.
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From Yadernaya Fizika, Vol. 65, No. 8, 2002, pp. 1438–1445.
Original English Text Copyright © 2002 by Wagner, Gontchar, Gettinger, Litnevsky, Ortlepp, Kamanin.
This article was submitted by the authors in English.
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Wagner, W., Gontchar, I.I., Gettinger, A.E. et al. Novel features of the fragment mass variance in fission of hot nuclei. Phys. Atom. Nuclei 65, 1403–1410 (2002). https://doi.org/10.1134/1.1501651
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DOI: https://doi.org/10.1134/1.1501651