1. Production of heavy neutron-rich nuclei around N=126 in multi-nucleon transfer (MNT) reactions
Long ZHU (祝龙)
Sino-French Institute of Nuclear Engineering and Technology
NuSYM2018, South Korea 1

2. Outline Background Dinuclear system (DNS) + GEMINI model Some Results
Shell effects on production cross sections
Incident energy dependence
Advantage of 238U induced reactions
Perspective of radioactive beam induced reactions
Summary

3. Outline Background Dinuclear system (DNS) + GEMINI model Some Results
Shell effects on production cross sections
Incident energy dependence
Advantage of 238U induced reactions
Perspective of radioactive beam induced reactions
Summary

4. Discovery of Nuclides proton neutron
It was estimated that about 7000 bound nuclides exist.
About 260 Stable nuclei
in nature.
By 2015, 3211 nuclides have been discovered.
Multinucleon Transfer ?
Spallation
N=126
Projectile Fragmentation
proton
N=82
Projectile Fission
neutron

5. No new isotope with N=126 is observed yet
One candidate: 136Xe+208Pb
Dubna
No new isotope with N=126 is observed yet
Pure proton transfer from lead to xenon might be rather favorable here because the lighter fragments formed in such a process are well bound (stable nuclei) and the reaction Q-values are almost zero.
V. Zagrebaev and W. Greiner, PRL 101, (2008)
E. M. Kozulin et al., PRC 86, (2012)

6. No new isotope with N=126 is observed yet GANIL
One candidate: 136Xe+198Pt
(Because of larger transfer probability of neutron)
No new isotope with N=126 is observed yet
GANIL
Great advantages of MNT reactions
than projectile fission
Deduced cross sections
Y. X. Watanabe, et al., PRL 115, (2015)

7. Difficulties for producing unknown nuclei
in MNT reactions
Experimentally
- Difficult to separate and detect the products.
- New methods and equipment need to be developed
Theoretically
- Not enough experimental data for development of model
- Difficult to make predictions

8. Outline Background Dinuclear system (DNS) + GEMINI model Some Results
Shell effects on production cross sections
Incident energy dependence
Advantage of 238U induced reactions
Perspective of radioactive beam induced reactions
Summary

9. DNS+GEMINI model
Transfer probability is governed by transport Master Equation:
Potential energy surface:
GEMINI for deexcitation (particle evaporation and fission)
G. G. Adamian, et al, Phys. Rev. C 68, (2003).
M. Schadel, et al. Phys. Rev. Lett. 48, 852 (1982).
S. Ayik, B. Schurmann, and W. Norenberg, Z. Phys. A 277, (1976)
L. Zhu, et al, JPG. 42, (2015)

10. Outline Background Dinuclear system (DNS) + GEMINI model Some Results
Shell effects on production cross sections
Incident energy dependence
Advantage of 238U induced reactions
Perspective of radioactive beam induced reactions
Summary

11. Shell effects Inverse Quasifission 160Gd + 186W
The injection position is on the side of the valley and the probability of leading to the configuration of 138Ba + 208Pb can be enhanced.
Increase of dissipated energy weakens the shell effects.
Inverse Quasifission
E. M. Kozulin et al., PRC 96, (2017)
L. Zhu et al., PRC 97, (2018)

12. 136Xe is not favorable for producing transtarget nuclei.
Because of the closed neutron shell (N = 82) in projectile 136Xe, the injection point is located at the bottom of the valley on PES for the reaction 136Xe + 186W. Hence, inner barriers need to be overcome in process of nucleon transfer.
136Xe is not favorable for producing transtarget nuclei.
Ec.m.=408MeV
Ec.m.=451MeV

13. Incident energy dependence of production cross sections
(The production yields of actinide neutron-rich nuclei strongly depend on the incident energy. However,
for producing heavy neutron-rich nuclei around N = 126 the incident energy effects are weak.)
High incident energy increases the primary cross sections, more neutrons will be evaporated during cooling process.
High fission probabilty
160Gd + 186W
V. I. Zagrebaev and Walter Greiner, PRC 83, (2011)
A. V. Karpov and V. V. Saiko, PRC 96, (2017)

14. Advantages of cross sections in MNT reactions
based on 238U
We expect the high cross sections based on:
The 238U shows large value of N/Z ratio (=1.59)
The mass asymmetry relaxation would promote the nucleons transferring from 238U to light partners
The neutron closed shell N=126 could attract the
neutrons flow from 238U to light partners

15. Advantages of cross sections in MNT reactions based on 238U
Shell effects
N/Z equilibration
Mass asymmetry relaxation

16. Advantages of cross sections in MNT reactions based on 238U
As we expected, 238U induced reactions show great advantage of cross sections
Ec.m. =1.15Vcont
2-4 orders of magnitude larger !!
With consideration of experimental measurement, such as beam intensity and kinematics, the 238U could be the target.
N=126

17. Radioactive beam induced reactions
(Beam intensities are too low in present equipment)
Based on beam intensities
proposed by SPIRAL2
>108 ions/s for 144Xe
AXe+208Pb
L. Zhu et al., PLB 767, 437–442 (2017)
S. Gales, Prog. Part. Nucl. Phys. 59, 22 (2007) .
L. Zhu et al., PRC 96, (2017)

18. Summary Shell closures play an important role in inverse quasifission
process
2. The production cross section of neutron-rich nuclei around
N = 126 weakly depends on the incident energy.
238U shows great advantages for producing heavy neutron-
rich nuclei around N=126.
With development of the modern radioactive beam facilities,
radioactive beam induced transfer reactions will be promising
approaches to fill the blank of nuclear map around last r-process
“waiting point”.

19. Thanks Collaborators: Jun Su, Chen-Chen Guo Sun Yat-sen University
Cheng Li, Feng-Shou Zhang Beijing Normal University
Pei-Wei Wen, Cheng-Jian Lin China Institute of Atomic Energy
Zhao-Qing Feng South China University of Technology
Xiao-Jun Bao Hunan Normal University
Thanks