Università degli Studi di Padova
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Dipartimento di Fisica "Galileo Galilei"
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S E M I N A R
I
O
LUNEDI'
13 NOVEMBRE 2006, ALLE ORE 15:00
IN AULA S
DIPARTIMENTO DI FISICA, UNIVERSITÀ DI PADOVA
Prof. Roman N. SAGAIDAK
JINR, Dubna
terrà
un seminario
dal
titolo:
"Fusion
probability in reactions leading
to the heaviest nuclei"
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Abstract. Production of the
heaviest nuclei in complete fusion reactions
induced by heavy ions has been considered in a systematic way in the
framework of the conventional barrier passing (fusion) model coupled
with the standard statistical model. Available data on the excitation
functions for fission and production of evaporation residues (ER) in
very asymmetric combinations induced by 12C-22Ne
on actinide target nuclei are described rather well with these models.
The data allow one to adjust model parameters quite definitely. For
reactions induced by 26Mg and heavier projectiles, when
quasi-fission effects are starting to appear in the entrance channel of
reactions, one had to introduce phenomenologically the quantity "fusion
probability" Pfus to reproduce the ER excitation functions
in the framework of the conventional "potential barrier - statistical
model" approach. The exponential dependence of Pfus on the
mean combined fissility was found in search for regularities in the
behavior of the Pfus values extracted empirically from the
data analysis. A scaling of the empirical fusion probabilities together
with the adjusted parameters of the models allow one to predict cross
section values for the unknown heaviest (superheavy) nuclei produced in
various projectile-target combinations.
Fernando SCARLASSARA