Molecular resonance and highly deformed fission fragments in Si-28+Si-28 -art. no. 014607

Citation
C. Beck et al., Molecular resonance and highly deformed fission fragments in Si-28+Si-28 -art. no. 014607, PHYS REV C, 6301(1), 2001, pp. 4607
Citations number
92
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
PHYSICAL REVIEW C
ISSN journal
0556-2813 → ACNP
Volume
6301
Issue
1
Year of publication
2001
Database
ISI
SICI code
0556-2813(200101)6301:1<4607:MRAHDF>2.0.ZU;2-L
Abstract
A high-resolution measurement of fragment-fragment-gamma triple coincidence events in the symmetric and near-symmetric mass exit channels from the Si- 28+ Si-28 reaction has been undertaken using the EUROGAM Phase II gamma -ra y spectrometer. The bombarding energy of E-lab(Si-28) = 111.6 MeV has been selected to populate the conjectured J(pi) = 38(+) quasimolecular resonance in the Ni-56 dinuclear system. In the Si-28+ Si-28 symmetric mass exit cha nnel, the resonance behavior is clearly verified at the chosen energy. The population of highly excited states in the Mg-24, Si-28, and S-32 nuclei is discussed within a statistical fusion-fission model. Evidence is presented for selective population of states in the Si-28 fragments arising from the symmetric fission of the Ni-56 compound nucleus. The enhanced population o f the K-pi=3(1)(-) band of the Si-28 nucleus, indicative of an oblate defor med shape, suggests that the oblate configuration plays a significant role in the resonant process. Fragment angular distributions for the elastic and low-lying inelastic channels as well as gamma -ray angular correlations fo r the mutual inelastic channel (2(+),2(+)) indicate that the spin orientati ons of the outgoing fragments are perpendicular to the orbital angular mome ntum. This unexpected result, which is different from the alignment found f or the resonance structures in the Mg-24+ Mg-24 and C-12 + C-12 systems, su ggests a situation where two oblate Si-28 nuclei interact in an equator-to- equator stable molecular configuration. A discussion concerning the spin al ignment and spin disalignment for different reactions such as C-12 + C-12, Mg-24+Mg-24, and Si-28 + Si-28 is presented.