Frankfurt 2014 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 46: Poster

HK 46.12: Poster

Thursday, March 20, 2014, 16:00–18:00, HZ Poster

From the law of Flynn to the Pyatkov effect — •Christian Ythier and Genevieve Mouze — Faculté des Sciences,Université de Nice, 06108 Nice cedex 2,France

The linear variation of the mean mass A(L) of the light fission products of an asymmetrically fissioning system as a function of its mass A(F) [1] results from the transfer of an almost constant number x(L) of nucleons from the primordial 208 lead core to the corresponding cluster of mass A(cl) = A(F) - 208. We show that A(L) = 82 + 1/2 A(cl) and that, without correction for prompt- neutron emission, x(L) equals 68 for the n-induced fission of 235 uranium and 60 for the spontaneous fission of 252 californium. The variation law can now be written A(L) = 1/2 A (F) - 22, i.e. x(L) = 186 - 1/2 A (F) . We suggest that the x(L) nucleons can condense into a cluster if they are hindered from reaching the primordial cluster by the accidental interposition of the nascent heavy fragment, a core of 126 nucleons formed in the destruction of the lead core :This situation can be realized in the conditions chosen by Pyatkov et al.[2] for observing the colinear ternary fission mode, i.e. the formation of clusters of mass 28(44), 126 and 68(60), with which 14(22) extra nucleons still can combine. [1] K.F. Flynn et al.,PRC, 5 (1972)1725 . [2] Yu.V. Pyatkov et al., EPJA, 45 (2010)20.