Fusion hindrance and SHE D. Boilley GANIL and Univ. Caen CEA, - - PowerPoint PPT Presentation
Fusion hindrance and SHE D. Boilley GANIL and Univ. Caen CEA, Saclay: On the prediction for the SHE production RCNP, Osaka: B. Giraud ( ) Yasuhisa Abe GANIL, Caen: ( )
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
CEA, Saclay:
B. Giraud
GANIL, Caen:
Anthony Marchix Yoann Lallouet
Ankara university:
Bülent Yilmaz
RCNP, Osaka:
(大阪大学核物理研究センター)
Yasuhisa Abe
(阿部恭久)
Huzhou Teachers’ College:
(湖州师范学院)
Caiwan Shen
(沈彩万)
GANIL and Univ. Caen
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
Can we guide the experiments ? What is the shell correction energy ? Models cannot be extrapolated from
Fusion hindrance
Extremely low cross sections
Few data with few information
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
Introduction
Premier point
Chapitre 1
Section 1
…
PRL 82 (1999) 5012
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
Quasi-elastic (target)
& PRL101, 072701 (2008)
Z = 124 A = 312 At least 12 % of the capture events with a life time longer than 10-18 s Z = 120 A = 296 At least 10 % of the capture events with a life time longer than 10-18 s Z = 114 A = 282 Very low statistic or no events with a life time longer than 10-18 s Fission barriers
From P. MÖLLER et al.,
59 (1995) 185
Mesurements at GANIL by crystal blocking techniques
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
Formalism:
Weisskopf or Hauser-
Feshbach
Bohr-Wheeler
Level density:
Bohr-Mottelson with
angular dependence
Level density
parameter:
Töke-Swiatecki Suppression of shell
energy corrections according to Ignatyuk
Collective
enhancement included
i
n P i1(t) (i f + i n)P i(t)
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
Fission vs neutron
evaporation
Bn=6 MeV & Bf
constant along the chain
Long fission times
Bf ≈ Bn Long fission time
We cannot
Fission time Bf=Bn
Pre-scission neutrons
D.B. et al, IJMP E17 (2008) 1681-1693
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
Experimental results for Z=120 and 124
Very large ΔEshell for the first isotopes of
Potential structure effects ?
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
E ? = 0 E = 5MeV E* = 20MeV E* = 2MeV
Preliminary
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
It is not a Monte-Carlo code to calculate very low
probabilities
It is based on a discretisation in bins of the energy
spectra:
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
Shell correction energy -> correction factor Damping Energy Ed
Originally, Ed=18.5 MeV
Reduced friction
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
Fitting the residue cross sections gives
… if we know the fusion cross section
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
Coulomb barrier
Inner barrier
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
K.-H. Schmidt & W. Morawek Rep. Prog. Phys. 54 (1991) 949
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
The value of the neck parameter differs from authors
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
V(ε)=f. ε ε
1
We solved the Smoluchowski equation
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
Fast degree of freedom (neck) vs slow degree of freedom (r)
Tensor coupling
Shift of the initial condition in r
Larger hindrance due to dynamical coupling!
V(ε)=f. ε ε
1
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011
Exact solution for a saddle made with 2 parabolas
On the prediction for the SHE production Kazimierz Dolny, Sept. 20011