Transcript Fission fragment angular distribution and isotopic

Fission fragment angular distribution and isotopic distributions
Fission fragment angular distributions
and isotopic distributions
L. Tassan-Got and n_TOF and SOFIA
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
232Th
fission fragment angular distribution (FFAD)
• Detection of the 2 fission fragments
• Fission direction given by the positions of the 2 fragments
• 9 Targets and 10 detectors tilted by 45°
• 1x235U 1x238U 1x237Np
6x232Th
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
Examples of angular distributions
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
Rules of thumb for FFADs
K 
2
0
FUSTIPEN - Caen – 13/10/2014
J eff T
2
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
Fissility effect
Lower fissility
lower K’s
higher barrier
lower temperature
higher positive anisotropy
FUSTIPEN - Caen – 13/10/2014
lower K0
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
Anisotropy for p+X at 40 MeV
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
Systematics of linear momentum transfer
At 40 MeV almost full momentum transfer: in most of the cases
the proton is captured by the target nucleus
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
SOFIA experiment
From courtesy of J. Taieb, T. Corbinet, J. Fiona-Martin, E. Pellereau, A. Chatillon
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
238U
Z1+Z2=92 selection
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
Mass resolution
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
Fission of 238U: mass yield
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
Fission of 238U: charge yield
• Even-odd effect=10% (<E*>~14 MeV) vs Lohengrin=24% (<E*>=6 MeV)
• Even-odd effect decreases with excitation energy
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
Fission of 238U: isotopic yields for heavy fragment
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
Fission of neutron deficient nuclei
x
FUSTIPEN - Caen – 13/10/2014
K.H. Schmidt et al., Nucl. Phys. A665 (2000) 221
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
Fission of neutron deficient nuclei
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
Fission of neutron deficient nuclei
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
Fission of neutron deficient nuclei
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
Energetics of Sn isotopes
for fission of 235U
FUSTIPEN - Caen – 13/10/2014
Courtesy of Julie Fiona-Martin
<𝜈>=Nf - N1 - <N2>
L. Tassan-Got
Fission fragment angular distribution and isotopic distributions
Fission of 238U: isotonic yield
• Even-odd effect=5% (<E*>~14 MeV) vs Lohengrin=5% (<E*>=6 MeV)
• Evaporation ?
FUSTIPEN - Caen – 13/10/2014
L. Tassan-Got