Effects of entrance channel and compound nucleus in the fusion cross sections for28Si+

Abstract

In order to study the physics responsible for a hmitation in angular momentum in heavy-ion fusion reactions, fusion cross sections for the reactions 2sSi+isSi, '60+~Ca, 3tS+s Si, and ' C+' Cr have been measured at several incident energies covering lower and higher energy regions by detecting the yields of the fusion-evaporation residues. The limiting angular momenta for fusion are extracted from the measured fusion cross sections and compared with calculations based upon several models. Through the systematic study of different entrance channels forming the same compound nucleus, a strong entrance channel effect has been observed for very asymmetric systems. Our conclusion is that the entrance channel is significant in limiting the fusion cross section in the higher energy region.

Deformation effects in56Ninuclei produced in28Si+Bhattacharya1, Rousseau2, Beck3 et al. 2001Phys. Rev. C392191View full textAdd to dashboardCite

“…From this systematic analysis, it can be observed that the magnitude of the quadrupole deformation that can be deduced for both 28,30 Siϩ 28,30 Si reactions is rather large: their parameter values are similar to the value obtained for the 32 Sϩ 27 Al reaction ͓9,19͔ but larger than the value corresponding to the 28 Siϩ 27 Al reaction ͓13͔. This leads to the striking conclusion that highly stretched configurations are required to account for the observed ␣-particle evaporation spectra.…”

Examination of fusion cross sections and fusion oscillations with a generalized Wong formula

“…Several other data sets for the 28Si + 28Si system exist [31][32][33] and indeed one of the aims of Aguilera et al [33] was to search for oscillations in this system. Unfortunately, they were unable to conclude the existence of structures within the 3% statistical error in their experiment.…”

“…His rule is based upon a microscopic resonating group method within a two-center harmonic-oscillator shell model. Essentially the barrier for even partial waves is deemed to be higher (or lower) than that for odd partial waves if the quantity _ (_iyW Y[ ni i: valence (32) is positive (or negative). In both of our cases Acore is even.…”

Structures in high-energy fusion data

“…It is difficult to calibrate the M3Y+repulsion interaction to the 28 Si+ 28 Si data by Gary and Volant [16] because they cover a relatively small range of energies. Fortunately, there is another data set by Nagashima et al [17] which covers a much broader range of energies, and the high energy data by Vineyard et al [18] are also very valuable because they determine a limiting or critical angular momentum for fusion, which is about L c = 38h.…”