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Veselsk, M.*; Andreyev, A. N.*; Antalic, S.*; Huyse, M.*; Mller, P.*; Nishio, Katsuhisa; Sierk, A. J.*; Van Duppen, P.*; Venhart, M.*
Physical Review C, 86(2), p.024308_1 - 024308_8, 2012/08
Times Cited Count:16 Percentile:64.96(Physics, Nuclear)Ichikawa, Takatoshi*; Iwamoto, Akira; Mller, P.*; Sierk, A. J.*
Physical Review C, 86(2), p.024610_1 - 024610_8, 2012/08
Times Cited Count:68 Percentile:94.47(Physics, Nuclear)Fission-fragment mass distributions are asymmetric in fission of typical actinide nuclei for nucelon number in the range and proton number in the range . For somewhat lighter systems it has been observed that fission mass distributions are usually symmetric. However, a recent experiment showed that fission of Hg following electron capture on HI is asymmetric. An earlier experiment has shown fission of Hg and nearby nuclei is symmetric, but with hints of asymmetric yield distributions up to about 10 MeV above the saddle-point energy. We calculate potential-energy surfaces for a typical actinide nucleus and for 12 even isotopes in the range Hg-Hg, demonstrating the radical differences between actinide and mervury potential surfaces. We discuss these differences and how the changing potential-energy structure along the mercury isotope chain affects the observed (a)symmetry of the fission fragments. We show that the mechanism of asymmetric fission is very different in proton-rich mercury isotopes compared to the actinide region.
Andreyev, A. N.*; Elseviers, J.*; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; Diriken, J.*; et al.
Physical Review Letters, 105(25), p.252502_1 - 252502_5, 2010/12
Times Cited Count:189 Percentile:97.23(Physics, Multidisciplinary)Ichikawa, Takatoshi; Iwamoto, Akira; Mller, P.*; Sierk, A. J.*
Physical Review C, 71(4), p.044608_1 - 044608_11, 2005/04
Times Cited Count:42 Percentile:89.8(Physics, Nuclear)We estimate the effective fusion barrier in the entrance channel in cold-fusion reactions in a model where the projectile deformation and quadrupole zero-point vibrational energy are taken into account. The effective fusion-barrier height is defined as the barrier energy at the target and projectile separation distance where the system becomes unstable with respect to projectile deformation. We also calculate five-dimensional potential-energy surfaces for the single compound system. For heavy systems the fusion barrier at touching becomes lower than the fission barrier just beyond the ground state of the compound system. Except for reactions in which the projectile is doubly magic or near doubly magic, the calculated quantities are consistent with the observed optimal energies for evaporation-residue formation.
Iwamoto, Akira; Ichikawa, Takatoshi; Mller, P.*; Sierk, A. J.*
Nuclear Physics A, 738, p.499 - 502, 2004/06
Times Cited Count:4 Percentile:30.85(Physics, Nuclear)no abstracts in English
Mller, P.*; Sierk, A. J.*; Iwamoto, Akira
Physical Review Letters, 92(7), p.072501_1 - 072501_4, 2004/02
Times Cited Count:154 Percentile:95.59(Physics, Multidisciplinary)no abstracts in English
Mller, P.*; Madland, D. G.*; Sierk, A. J.*; Iwamoto, Akira
Nature, 409(6822), p.785 - 789, 2001/02
Times Cited Count:287 Percentile:99.33(Multidisciplinary Sciences)no abstracts in English
Iwamoto, Akira; Mller, P.*; Madland, D. G.*; Sierk, A. J.*
AIP Conference Proceedings 597, p.243 - 248, 2001/00
We present calculations of fission potential energy surface based on Strutinsky's prescription for realistic shape parameterization of the fissioning nuclei. It involves 5 shape parameters from which we obtain 5-dimensional potential energy surface of more than 2.5 million points. The analysis of the saddle point was performed without any approximation and we obtained the following understanding of the fission process. (1) Most of the actinide nuclei have the lowest two saddle points, one is mass-symmetric and the other is mass-asymmetric. (2) The relative height of these two saddles depends on the fissioning nucleus and experimentally observed mass division mode was well understood from the properties of the lowest saddle point. (3) Bimodal feature of Fm isotopes was well understood from the analysis of the saddle points. (4) Degree of the mass asymmetry of the most probable mass division was well understood from the potential energy surface.