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FIZIKA B 12 (2003) 2, 117 - 134
 
WEAK ABSORPTION AND RESONANCES IN LIGHT HEAVY-ION REACTIONS INDUCED BY
THE NON-a-TYPE 14C NUCLEUS
SUZANA SZILNERa,b, FLORENT HAASb and ZORAN BASRAKa
aRuđer Bošković Institute, HR-10 002 Zagreb, Croatia
bInstitut de Recherches Subatomiques, CNRS-IN2P3/ULP, Strasbourg, France
Received 28 January 2003; revised manuscript received 19 March 2003
Accepted 15 September 2003 Online 3 March 2004
The observation of resonant structures attributed to nuclear molecular configurations
in a-type systems involving the 12C and 16O
nuclei is a clear signature of a weak and surface-transparent absorption in these light
heavy-ion reactions at energies around and up to well above the Coulomb barrier. Such a
weak absorption, i.e. nuclear-surface transparency, is also predicted in reactions induced
by the 14C nucleus owing to the very special structure of low-lying states of
this non-a-type nucleus. The experimental search for resonant
structures in the 14C +14C, 14C +12C
and 14C +16O reactions undertaken by the Strasbourg-Zagreb
collaboration is described and discussed in the context of weak-absorption phenomena.
Strong and correlated resonances have been observed in the three systems studied and
particularly in those decay channels which are sensitive to the largest partial waves in
the entrance channel. As the incident energy increases, weak and surface-transparent
absorption gives rise to refractive effects, i.e to the nuclear rainbow. Indeed, nuclear
rainbows have been observed recently in the same a-type 12C +12C,
12C +16O and 16O +16O systems in
which prominent nuclear molecular resonances have been reported at lower energies. It is
predicted that such refractive effects should also be observed in the 14C-induced
reactions at energies above ~5MeV per nucleon.
PACS numbers: 25.70.Bc, 25.70.Ef, 25.70.-z:
UDC 539.17
Keywords: heavy ions, 14C radioactive beam, 14C targets,
molecular resonances, refractive effects, nuclear rainbow
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