Fragmentation-induced fission reactions of 236U in inverse kinematics to investigate the pre-fragment angular momentum parameterizations

EuNPC2022 conference

1. Fragmentation-induced fission reactions of
236
U
in inverse kinematics to investigate the pre-fragment angular
momentum parameterizations
José Luis Rodríguez-Sánchez
University of Santiago de Compostela
27
th
October 2022
EuNPC2022
236
U

2. 2
Nuclear fission
Complex decay process
J.L. Rodríguez-Sánchez
A diffusion process along the nuclear potential landscape based
on transport approaches like
Langevin equation
Fokker-Planck equation
dν
dt
=−βν−
1
m
∂
∂x
U(x)+
F'(t)
m
∂W
∂t
=[
−∂
∂x
ν+
∂
∂ν(
βν−
1
m
∂
∂x
U(x))
+
βκT
m
∂
2
∂ν
2]
W
The main inputs are the potential U(x) and the dissipation parameter β
Main observables: Fission probabilities & particle emission

3. 3
Nuclear fission
Complex decay process
J.L. Rodríguez-Sánchez
A diffusion process along the nuclear potential landscape based
on transport approaches like
Langevin equation
Fokker-Planck equation
dν
dt
=−βν−
1
m
∂
∂x
U(x)+
F'(t)
m
∂W
∂t
=[
−∂
∂x
ν+
∂
∂ν(
βν−
1
m
∂
∂x
U(x))
+
βκT
m
∂
2
∂ν
2]
W
The main inputs are the potential U(x) and the dissipation parameter β
Main observables: Fission probabilities & particle emission
At low excitation energies the dynamics is governed by the
macroscopic and microscopic components of the nuclear
potential leading to shell effects in the mass asymmetry parameter
Main observables
Charge and mass distributions of the fission fragments
Symmetric
Asymmetric

4. 4
Implication in many domains
J.L. Rodríguez-Sánchez
Nuclear structure
at large deformation
Dynamics of
nuclear matter
Nuclear astrophysics
(r-process and isomers)
Production of
radioactive ion beams
Production of hypernuclei
(with strange quarks)
Medical radio-tracers
Production of energy
Nuclear fission

5. 5
Implication in many domains
J.L. Rodríguez-Sánchez
Nuclear structure
at large deformation
Dynamics of
nuclear matter
Nuclear astrophysics
(r-process and isomers)
Production of
radioactive ion beams
Production of hypernuclei
(with strange quarks)
Medical radio-tracers
Production of energy
Nuclear fission
Sierk PRC 33, 6 (1986)

6. 6
Pre-fragment angular momentum in ABRASION models
J.L. Rodríguez-Sánchez
Angular momentum probability distribution
Spin cut-off parameter A. S. Goldhaber et al., Phys. Lett. B 53, 306 (1974)
Phys. Rev. C 95, 014610 (2017)PLB 632, 203 (2006)
Clear underestimation of isomeric ratios for
215
Ra
m
&
53
Fe
m
215
Ra
m
53
Fe
m
112
Sn
84
Kr
78
Kr
58
Ni
Different projectiles:
58
Ni,
78,84
Kr,
112
Sn

7. 7
Pre-fragment angular momentum in ABRASION models
J.L. Rodríguez-Sánchez
Angular momentum probability distribution
Spin cut-off parameter A. S. Goldhaber et al., Phys. Lett. B 53, 306 (1974)
Phys. Rev. C 95, 014610 (2017)PLB 632, 203 (2006)
Clear underestimation of isomeric ratios for
215
Ra
m
&
53
Fe
m
215
Ra
m
53
Fe
m
112
Sn
84
Kr
78
Kr
58
Ni
Different projectiles:
58
Ni,
78,84
Kr,
112
Sn
x 5
Liège intra-nuclear cascade model (INCL)
ABRABLA
D. Mancusi et al., Phys. Rev. C 90, 054602 (2014)
J.-J. Gaimard et al., Nucl. Phys. A 531, 709 (1991)
M. de Jong et al., Nucl. Phys. A 613, 435 (1997)
Comparison to dynamical models

8. 8
Production of secondary exotic nuclei at the FRS
J.L. Rodríguez-Sánchez
Y. Yan, PhD Thesis, IPN Orsay (2016)
M. Feijoo, PhD thesis, University of Santiago de Compostela (2021)
A
Z
=
e
u
Bρ
γβc

9. 9
Fission setup for studying exotic nuclei
J.L. Rodríguez-Sánchez et al.,
Phys. Rev. C 91, 064616 (2015)
E. Pellereau et al.,
Phys. Rev. C 95, 054603 (2017)
● Charge resolution ~ 0.4 units
● Magnetic field 1.68 T
● Position resolution ~200 µm
● ToF resolution 40 ps
J.L. Rodríguez-Sánchez
Complete kinematics measurements of fission fragments in inverse kinematics
Twin-MUSIC
MWPC Twin-MUSIC
ToF Wall
Dipole
Active target
● Coulex-induced fission reactions
● Fragmentation-induced fission reactions
J.L. Rodríguez-Sánchez et al., Phys. Rev. C 91, 064616 (2015)
E. Pellereau et al., Phys. Rev. C 95, 054603 (2017)

10. 10
Results from charge distributions
J.L. Rodríguez-Sánchez
● Charge correlation between both fission fragments
M. Feijoo, PhD thesis, University of Santiago de Compostela (2021)

11. 11
Model calculations for fragmentation-induced fission reactions
J.L. Rodríguez-Sánchez
Nucleus-Nucleus collision described by the Liège intra-nuclear cascade model (INCL++)
- Kinetic energy range from few MeV/u to 20 GeV/u
- MC approach to solve transport equations
- Emission of neutrons, protons and clusters
- Production of baryonic resonances (Δ,N*) and exotic channels with hyperons
- Pauli blocking to ensure energy and momentum conservation
- Characterization of the excited nucleus (A,Z,E*,J)
Deexcitation model ABLA++
- MC approach to describe the dynamics
- Emission of γs, hyperons, light particles and IMFs
- Fission
D. Mancusi et al., Phys. Rev. C 90, 054602 (2014)
J. L. Rodríguez-Sánchez et al., Phys. Rev. C 105, 014623 (2022)
236
U @ 650 MeV/u

12. 12
Comparison to model calculations
J.L. Rodríguez-Sánchez
● Fission yields and widths of the charge distribution of fission fragments show that the angular momentum
description used in ABRASION models fails

13. 13
Comparison to other models and isomeric ratios
J.L. Rodríguez-Sánchez
INCL+ABLA++
● INCL predicts larger angular momentum tails for fragmentation
residues, which are in better agreement with experimental results
● Pre-fragments produced with large angular momentum end in
the fission channel
● Better predictions for isomeric ratios of
53
Fe
112
Sn84
Kr
78
Kr
53
Fe
Zs. Podolyák et al.,Physics Letters B 632, 203 (2006)
S. Pal et al.,Physics Letters B 665, 164 (2008)
X. L. Tu et al.,Phys. Rev. C 95, 014610 (2017)
238
U+Be→
211
Fr
238
U+Be at 1GeV/u

14. 14
Conclusions
J.L. Rodríguez-Sánchez
● The SOFIA-R3B experimental setup has been for the first time used to investigate the reaction

236
U+Al at 650 MeV/u. The beam of
236
U was produced with the fragment separator FRS and the
fission reactions were induced by using an active target made of U, Pb and Al layers.
● The new experimental data have been used to study for the first time the effects of the pre-fragment
angular momentum in the fission yields
> Pre-fragment angular momentum parameterizations used by statistical ABRASION models
underestimate the probability of populating states with large angular momentum, while intranuclear
cascade (INCL) model gives better predictions
> INCL also gives a better prediction of isomeric ratios
● The ABRASION parameterizations used for the angular momentum must be improved to include the
the fragmentation and fission channels

15. 15
SOFIA collaboration
Sponsors:
Thank you for your attention!