1. Introduction
Experimental result
Discussion
Conclusion
Impact of the intruder orbitals on the structure of neutron-rich Ag isotopes
KIM, Yung-Hee
GANIL
9Be+238U fission experiment
Introduction
n-rich Ag isotopes : Triaxiality
Two worlds in shell model
Results
Spectra & level scheme
Signature splitting : Evidence of triaxiality
Discussion
Shell model calculation
Conclusion
I’d like to present result from prompt gamma-ray spectroscopy from fission fragment from 9Be+238U near the Coulomb barrier
Investigating the Impact of the intruder orbitals on the structure of neutron-rich Ag isotopes

2. Introduction
Experimental result
Discussion
Conclusion
238U(9Be,fγ) prompt γ-ray spectroscopy on isotopically identified fragments
ΔZ/Z ∼ 1.5%
ΔA/A ∼ 0.45% Ag
A. Navin et al., Physics Letters B 728 (2014) 136–140
VAMOS++
9Be (10μm)
Unlike many of you who are studying fission process it self,
we use fission as a tool to populate n-rich nuclei near Sn and to study the structure.
In 2011 The fission of 238U on 9Be was carried out in GANIL
238U to 9Be has capable of populating n-rich nuclei over wide range of elements and it can excite to relatively high spin states.
The fission was carried out inverse kinematics to get advantage from kinematical focusing
The VAMOS++ large acceptance spectrometer coupled to EXOGAM Clover Ge-Detector array was used for prompt-g-ray spectroscopy.
Due to large acceptance and isotopic identification of the VAMOS++ (click)
Which has very good resolution accounting the energy is around the Coulomb barrier.
we could get prompt g-ray spectroscopy without any unambiguity with good statistics in n-rich nuclei.
From these advantages, this one experiment could produce results with various topic in nuclear structure.
Doppler correction resolution 1.3MeV ~10keV in backward direction middle 15keV FWHM
238U(9Be,fγ) transfer/fusion-fission
Various n-rich nuclei
(rel.) High spin state
VAMOS++ & EXOGAM
Wide acceptance + isotopic ID
In-beam γ-ray spectroscopy w/ good Doppler correction
238U (6.2 MeV/u)
FF1
FF2
20°
EXOGAM
S. Pullanhiotan et al., Nucl. Instr. and Meth. A, 593,(2008)

3. 238U(9Be,fγ) prompt γ-ray spectroscopy -Single particle motion
Introduction
Experimental result
Discussion
Conclusion
238U(9Be,fγ) prompt γ-ray spectroscopy -Single particle motion
Single particle motion (Large-scale shell-model)
Sb/ In: E2/M1 competition, natural seniority breaking
Cd: shell model interaction
132Te: shell model interaction
Collective motion (IBM/TPSM)
105,106Zr: Triaxiality/shape co-existence
Rh: Triaxiality
The various results can be cartegorized in two main topics, first is the subject more concerned about single particle motion near the shell closure.
One good example is the Sb/In structure across the Sn shell closure.
These nuclides were interpreted by large scale shell model calculations which is fully microscopic point of view.
Collaboration EXOGAM+VAMOS / GAMMASPHERE
Pr: Resolving structural uncertainty
M. Rejmund et al., Phys. Lett. B 753 (2016) 86–90

4. 238U(9Be,fγ) prompt γ-ray spectroscopy -Collective motion
Introduction
Experimental result
Discussion
Conclusion
238U(9Be,fγ) prompt γ-ray spectroscopy -Collective motion
Single particle motion (Large-scale shell-model)
Sb/ In: E2/M1 competition, natural seniority breaking
Cd: shell model interaction
132Te: shell model interaction
Collective motion (IBM/TPSM)
105,106Zr: Triaxiality/shape co-existence
Rh: Triaxiality
On the otherhand for nuclides in the midshell, the collective properties of nuclides were investigated.
such as triaxiality of nuclides in the rotational band or shape co-exsistance.
They are interpreted by more collective models such as TPSM or IBM calculations using deformed basis in the wave functions.
Collaboration EXOGAM+VAMOS / GAMMASPHERE
Pr: Resolving structural uncertainty
A. Navin et al., Phys. Lett. B. in press (2016)

5. 238U(9Be,fγ) prompt γ-ray spectroscopy Ag isotopes
Introduction
Experimental result
Discussion
Conclusion
238U(9Be,fγ) prompt γ-ray spectroscopy Ag isotopes
Single particle motion (Large-scale shell-model)
Sb/ In: E2/M1 competition, natural seniority breaking
Cd: shell model interaction
132Te: shell model interaction
Proton # Pr Te Sb
Collective motion (IBM/TPSM)
105,106Zr: Triaxiality/shape co-existence
Rh: Triaxiality
Collective motion through microscopic view
113, Ag Sn In
In nuclear chart, you can see the result from this experiment with different topics
What I’d like to show you is the combining these two topics for nuclei in between which is the neutron rich Ag isotope. Ag Rh Zr
Neutron #
Collaboration EXOGAM+VAMOS / GAMMASPHERE
Pr: Resolving structural uncertainty

6. Expected triaxial deformation at 113-121Ag
Introduction
Experimental result
Discussion
Conclusion
Expected triaxial deformation at Ag Ag
= Distance from
shell closure
Y. X. Luo et al., J. Phys. G: Nucl. Part. Phys. 31 (2005) 1303–1327
For more Ag isotopes triaxiality is expected to continue from the
systematics from lighter Ag and also from systematics from odd-Z isotopes Y-Nb-Rh
where the triaxial deformation increase as Z moves closer to the Sn shell closure.
Systematics Y-Nb-Rh  closer shell closures, stronger triaxial deformation
Triaxiality near n-rich nuclei at lighter Ag isotopes A≤110
Observable:
Direct: Doublet bands (Chiral, Wobbling)
Indirect: Large signature splitting, Signature inversion

7. Expected triaxial deformation at 113-121Ag
Introduction
Experimental result
Discussion
Conclusion
Expected triaxial deformation at Ag
108Ag
109Ag
J. Sethi et al. Phys. Lett. B 725 (2013) 85–91
S. Roy et al. Phys. Lett. B 710 (2012) 587–593
The n-rich Ag isotopes the triaxial deformation can be expected
For the Ag isotope below A 110 triaxial deformation was confirmed by the observable
directly chiral dublet bands or indirectly by large signature splitting which is compared with deformed shell models.
Systematics Y-Nb-Rh  closer shell closures, stronger triaxial deformation
Triaxiality near n-rich nuclei at lighter Ag isotopes A≤110
Observable:
Direct: Doublet bands (Chiral, Wobbling)
Indirect: Large signature splitting, signature inversion

8. Two worlds in shell model
Introduction
Experimental result
Discussion
Conclusion
Two worlds in shell model
M. Rejmund et al., PRC 93, (2016)
A. Navin et al., Physics Letters B 728 (2014) 136
As you may well know,
the shell model interpretations are quite different between the different region.
Where near the shell closure, the sphereical shell model with spereical basis are used,
It is limited in this region due to the expontially increasing model space moving from the shell closure.
But recently due to increaed computing power and development of calculation techniques it is expanding its calculable regions.
On the otherhand for the midshell nuclides deformed shell models or Nilsson like models are used.
Many models of this kind assumes deformed core or basis, with few quasi-particle outside of the core,
From this it has significantly less computing power and give intuitive explanation of the collective motion of the nucleus.
For the neutron rich Ag are now in the border between these two worlds and
previously light Ag isotope near stability were explained by deformed shell models.
But if it could be interpreted with spherical shell model would give different view view
And it can make bridge between two worlds.
From these motivations I would like to show the experimental results.
Spherical shell model
Spherical basis
Nuclei near shell closure
High computing power needed
Increasing calculable regions
Deformed shell model
Deformed basis (assumption/exp. data deformation of core is needed)
Mid-shell nuclei
Less computing power
n-rich Ag can be bridge between two worlds

9. Spectrum of 113,116-121Ag New spectra 113,118-121Ag
Introduction
Experimental result
Discussion
Conclusion
Spectrum of 113, Ag x3 x3 x3
This is the newly observed spectrum of odd-A Ag isotopes,
these ones are singles spectrum and the insets are showing coincidence spectra
The analysis was done until the coincidence spectrum could be observed
As you can see the largest peaks connecting to each other shows similar energy
This is the newly observed even-A Ag isotopes of 118 and 120 Ag isotopes,
You can see there is doublet in the low E and high E peak with similar energy showing similar spectra.
New spectra 113, Ag
Similar spectra from the light Ag

10. Smooth evolution of the Level scheme
Introduction
Experimental result
Discussion
Conclusion
Smooth evolution of the Level scheme
Odd-A
Even-A v v v v
M.-G. Porquet et al., Eur. Phys. J. A 18 (2003) 25–30
This is the level scheme of newly observed odd-A Ag isotopes,
You can see the level have large energy straggling and it evolves smoothly for different isotopes
In case of even-A Ag the levels are more equidistance different from odd-A Ag.
And different isotopes show similar energy.
This similar structure for different isotope doesn’t end only in this isotopes but they are quite consistent through out very long chain of isotopes. v v
Smooth evolution of level energies
Odd-A large energy staggering
Even-A regular level spacing

11. Evidence of triaxiality in odd-A -Large signature splitting
Introduction
Experimental result
Discussion
Conclusion
Evidence of triaxiality in odd-A -Large signature splitting
This is the signature splitting of odd–A Ag
which measures the energy straggling of different levels
And the large signature splitting are one of the eveidence of the triaxiality.
What is striking is the large and constant signature splitting over very long chain of isotopes
Through out the N 50 to 82 magicity in low lying states.
This is quite different from Rh or lighter isotopes where signature splitting shows evolution.
LARGE & CONSTANT signature splitting

12. Evidence of triaxiality in odd-A -Large signature splitting
Introduction
Experimental result
Discussion
Conclusion
Evidence of triaxiality in odd-A -Large signature splitting
This is the signature splitting of odd–A Ag
which measures the energy straggling of different levels
And the large signature splitting are one of the eveidence of the triaxiality.
What is striking is the large and constant signature splitting over very long chain of isotopes
Through out the N 50 to 82 magicity in low lying states.
This is quite different from Rh or lighter isotopes where signature splitting shows evolution.
LARGE & CONSTANT signature splitting over long chain of isotopes 50<N<82

13. Evidence of triaxiality in even-A -Signature inversion
Introduction
Experimental result
Discussion
Conclusion
Evidence of triaxiality in even-A -Signature inversion
This constancy in signature spltting is also observed in even A Ag until mass 114
but in this case they show a inversed signature splitting where favored signature have larger S(J) different from odd-A case
The singnature inversion it is also thought as a finger print of triaxiality
although there debate going on why signature inversion arises.
Constant signature inversion (N<69)

14. Evidence of triaxiality in even-A -Signature inversion
Introduction
Experimental result
Discussion
Conclusion
Evidence of triaxiality in even-A -Signature inversion
But when we move to N=69 the signauture inversion becomes smaller and it changes to normal signature when it goes to A=118,
A=120
So from these systematics for long chain of isotopes the question arised that
What is the origin of large and constant signature splitting of odd-A Ag isotopes
And why in even-A isotopes signature evolved from signature inversion to normal signature splitting.
So to understand this behavior, microscopic large scale shell model calculation were carried out.
Constant signature inversion (N<69)
Normal signature (N>69)
N=69

15. Large-scale shell-model calculation
Introduction
Experimental result
Discussion
Conclusion
Large-scale shell-model calculation v
The calculation was carried out in the restricted space of jj45pna interaction shown here.
This is because of the large space needed for the calculation and also it was not able to reproduce
Their structure for the heavier Ag isotopes.
The calcualtion result gives very good agreement with the experimental value reproduing its level order, energy.
There is some shriked can be seen in the high spin states which is also seen in Cd calculation
Probabliy due to small space we used.
This calcualtion was also used for the Cd, In isotopes and showed good agreement with the experiment.
Diagonal neutron-neutron interaction was adjusted
1p3/2
1f5/2
LSSM calculation in restricted space jj45pna interaction
π(g9/2, p1/2), ν(d3/2, s1/2, h11/2) orbitals
Good agreement with experiment
(level ordering & energy reproduction)

16. Large-scale shell-model calculation
Introduction
Experimental result
Discussion
Conclusion
Large-scale shell-model calculation
Odd-A
Even-A v
This is showing all the calculation for this experiment. Which we can see good agreement between the experiment and the calculation .
LSSM calculation in restricted space jj45pna interaction
π(g9/2, p1/2), ν(d3/2, s1/2, h11/2) orbitals
Good agreement with experiment
(level ordering & energy reproduction)

17. Shell-model calculation result -signature splitting-
Introduction
Experimental result
Discussion
Conclusion
Shell-model calculation result -signature splitting-
Ag : Large signature splitting
116Ag : Signature inversion
Ag : Normal signature
All features are well reproduced!
Odd-A
The signature spltting wise the large signature splitting at low lying state is well reproduced.
And evolution from signature inversed 116Ag to normal signature in 118, 120 Ag are also well reproduced.
The wave function shows that πg9/2 νh11/2 intruder state scheme dominates,
therefore to get more deeper insight, we carried out more simpler calculation including only two orbital
Even-A
Dominant contribution from πg9/2-3xνh11/2 m intruder orbital

18. Two-shell shell-model calculation Signature splitting
Introduction
Experimental result
Discussion
Conclusion
Two-shell shell-model calculation Signature splitting
Large Signature splitting
Only πg9/2 νh11/2 space
Odd-A :
Large signature splitting
Even-A :
Signature inversion
Normal signature
Essential features are
reproduced
Odd-A
Signature inversion
favored
The calculation only including the two shell shows quite good reproduction of level order and energy accounting its simplicity,
And when we calculate signature splitting it reproduces the essential features of the experiment
Where the large and relatively constant signature splitting in odd-A Ag as function of neutron occupancy in h11/2 shell
And also evolution from signature inversion to normal signature in even-A Ag
The h11/2 occupancy corresponds to exactly to the full calculation result where 116Ag is 3.5 and 118Ag is 5.
And as the h11/2 occupancy is increased more than 7 the signature is almost constant
This evolution corresponds to where particle-hole interaction changes to the hole-hole interaction.
unfavored
116Ag Nh11/2=3.5
Even-A
118Ag
Normal Signature
Even-A Signature evolution :
particle-hole (Nh11/2<6)
 hole-hole (Nh11/2>6)
120Ag

19. Introduction
Experimental result
Discussion
Conclusion
New level scheme of 113, Ag
Striking evolution in signature splitting in 50<N<82 evidenced towards triaxialty
Microscopic shell model reproduces structure without any assumption in deformation
Essentially understood by simple intruder g9/2, h11/2 shell-model  Simplicity under complicated structure due to band from intruder orbital πg9/2-3xνh11/2m
MORE features!!
e.g. Inheritance from Cd in Ag isotope, natural seniority breaking
Even-A Ag
In conculsion
The new level scheme of 113,121Ag was determined.
The large consistancy in level energy and signature splitting could be obseved which is strikin.
To understand the structure of this nuclei we carried out large scale shell model calculation
Which reproduced the levels very well for the first time in this region.
Although the structure looks quite complicated,
The structures could be essentially understood with only two intruder orbital h11/2 g9/2
There are more features I could not present due to time limit but if you are interested please ask me LOL….

20. Merci 
Thank you