Excitation energy dependence of fragment-mass distributions from fission of
Hg formed in fusion reactions of
Ar +
Sm
Nishio, Katsuhisa
; Andreyev, A. N.*; Chapman, R.*; Derkx, X.*; D
llmann, C. E.*; Ghys, L.*; He
berger, F. P.*; Hirose, Kentaro
; Ikezoe, Hiroshi*; Khuyagbaatar, J.*; Kindler, B.*; Lommel, B.*; Makii, Hiroyuki
; Nishinaka, Ichiro; Otsuki, Tsutomu*; Pain, S. D.*; Sagaidak, R.*; Tsekhanovich, I.*; Venhart, M.*; Wakabayashi, Yasuo*; Yan, S.*
Mass distributions of fission fragments from the compound nuclei
Hg and
Hg formed in fusion reactions
Ar+
Sm and
Ar+
Sm, respectively, were measured at initial excitation energies of
(
Hg)=,33
66 MeV and
(
Hg)=,48
71 MeV. In the fission of
Hg, the mass spectra were well reproduced by assuming only an asymmetric-mass division, with most probable light and heavy fragment masses
/
79
101. The mass asymmetry for
Hg agrees well with that obtained in the low-energy
/EC-delayed fission of
Tl, from our earlier ISOLDE(CERN) experiment. Fission of
Hg is found to proceed in a similar way, delivering the mass asymmetry of
/
83
107, throughout the measured excitation energy range. The persistence as a function of excitation energy of the mass-asymmetric fission for both proton-rich Hg isotopes gives strong evidence for the survival of microscopic effects up to effective excitation energies of compound nuclei as high as 40,MeV. This behavior is different from fission of actinide nuclei and heavier mercury isotope
Hg.