Influence of Collective Surface Motion on the Threshold Behavior of Nuclear Fusion

Abstract

to the superspace. Such localized configurations could then help our understanding of quark con-finement^° and hadronic matter (bags). These solutions could also shed light on the bubble formation in early universe.It is a pleasure to thank R. Jackiw for suggestions and discussions, and A. Kupiainen and A. Luther for discussions. Part of this work was completed at Helsinki University of Technology and I thank E. Byckling and K. Kajantie for their hospitality. This work was supported in part by the U. S. Department of Energy under Contract No. DE-ACO2-76ERO3069.Note added,-^After completion of this manuscript I learned that J. Cardy (University of Washington, Seattle) has also found finite-energy solitons and arrived at similar conclusions. <^^present address. ^a Grinstein, Phys. Rev. Lett. ^, 944 (1976);

Competition between binary reactions and fusion in heavy-ion collisions at the Coulomb barrier

“…The accuracy of the cross sections depends also, in a complex way, on the knowledge of the decay schemes of the relevant radioactive isotopes. A detailed comparison of yields obtained by K X-ray and 7-ray activation techniques with absolute yields based on ion counting behind the velocity filter SHIP [23], showed that the yields from the (100% efficient) ion counting technique were reproduced rather well by the activation techniques on the average, with typical errors of 15%. …”

Cross section systematics for the lightest Bi and Po nuclei produced in complete fusion reactions with heavy ions

“…We assume that the ER formation proceeds via two independent steps: complete fusion of projectile and target nuclei to form a compound nucleus, followed by its decay via the competition between nuclear fission, particle evaporation, and γ decay. The fusion cross section was calculated within a one-dimensional barrier penetration model [41][42][43] which uses the partial wave summation according to the expression…”

“…Subbarrier fusion is a complex phenomenon, and for detailed discussion of different processes (e.g., channel coupling, transfer and inelastic couplings, static and dynamic deformation) leading to cross section enhancement, we refer to reviews [43]. In our study, we exploited a phenomenological model that involves the barrier fluctuations (BF) with an amplitude correlated with the collective surface properties of the colliding nuclei [9,41,43]. As discussed in the literature, this rather simple model allows a surprisingly good description of the fusion excitation functions over the full energy region in terms of only two parameters: the average barrier height B 0 and its standard (Gaussian) deviation σ (B 0 ).…”

“…As expected, above the barrier, both the IP and BF approaches give very similar calculated cross sections as exemplified by the data for 191 Bi (p2n) and 191 Po (3n). The chosen value of σ (B 0 ) is within the range of 3-5% recommended in the literature for the reactions involving spherical partners [7,41]. Owing to the scarcity of our data in the subbarrier region, we did not aim at an exact reproduction of the experimental data, rather we wanted to show the trend of the calculated cross sections in cases where static and/or dynamic effects are considered (though phenomenologically).…”

Examining the role of transfer coupling in sub-barrier fusion ofTi46,50+Sn124

“…As an example, the sub-barrier fusion enhancement in 32 [37,38]. It is worth noting that 32 S has a very collective high-lying octupole state, like 40 Ca.…”