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1.
Phys Rev Lett ; 119(22): 222501, 2017 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-29286806

RESUMO

Fission-fragment mass distributions were measured for ^{237-240}U, ^{239-242}Np, and ^{241-244}Pu populated in the excitation-energy range from 10 to 60 MeV by multinucleon transfer channels in the reaction ^{18}O+^{238}U at the Japan Atomic Energy Agency tandem facility. Among them, the data for ^{240}U and ^{240,241,242}Np were observed for the first time. It was found that the mass distributions for all the studied nuclides maintain a double-humped shape up to the highest measured energy in contrast to expectations of predominantly symmetric fission due to the washing out of nuclear shell effects. From a comparison with the dynamical calculation based on the fluctuation-dissipation model, this behavior of the mass distributions was unambiguously attributed to the effect of multichance fission.

2.
Phys Rev Lett ; 95(10): 102502, 2005 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-16196924

RESUMO

alpha-gamma and alpha-electron coincidence spectroscopy for a short-lived heavy actinide nucleus (257)No (T(1/2) = 24.5 s) has been performed using a gas-jet transport system and an on-line isotope separator. Spin-parities of excited states in (253)Fm fed by the alpha decay of (257)No have been identified on the basis of the measured internal conversion coefficients. The nu3/2(+)[622] configuration has been assigned to the ground state of (257)No as well as to the 124.1 keV level in (253)Fm. It was found that the ground-state configuration of (257)No is different from that of lighter N = 155 isotones.

3.
Phys Rev Lett ; 89(5): 052701, 2002 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-12144438

RESUMO

The excitation function for fusion evaporation in the (60)Ni+ (89)Y system was measured over a range in cross section covering 6 orders of magnitude. The cross section exhibits an abrupt decrease at extreme sub-barrier energies. This behavior, which is also present in a few other systems found in the literature, cannot be reproduced with present models, including those based on a coupled-channels approach. Possible causes are discussed, including a dependence on the intrinsic structure of the participants.

4.
Phys Rev C Nucl Phys ; 54(4): 2043-2046, 1996 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9971554
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