1. Structure of Sb nuclei around 132Sn as a testing ground for realistic shell model interactions
Bartłomiej Szpak
Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Poland
B. Szpak, B. Fornal, P. Bednarczyk, M. Ciemała, N. Cieplicka, M. Kmiecik, W. Królas, A. Maj
Institute of Nuclear Physics, Polish Academy of Sciences, PL Krakow, Poland
S. Leoni1,2, S. Bottoni1,2, G. Benzoni2, A. Bracco1,2, F. Crespi1,2
1 Università degli Studi di Milano, Via Celoria 16, 20133, Italy 2 INFN, sezione di Milano, Italy
K. Rusek
Heavy Ion Laboratory, University of Warsaw, Poland
R. Raabe
Instituut voor Kern-en Stralingsfysisca, KU Leuven, Belgium
S. Lunardi, D. Bazzacco, S. Lenzi, R. Menegazzo, D. Mengoni, C. Michelagnoli, F. Recchia, C.A. Ur
Department of Physics, University of Padova and INFN, Padova, Italy
G. de Angelis, D.R. Napoli, J. Valiente-Dobon,
INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy
G. de France, E. Clement, C. Michelagnoli
GANIL, Caen, France

2. Cluster transfer reactions
We propose a method for gamma-ray spectroscopic studies of low-lying structures in nuclei lying close to the projectile nucleus.
The method relies on the triton transfer process induced by radioactive beams on a 7Li target.
AX + 7Li A+3-xY+α+xn Z
Z+1
133 Sn
134 Sb
Sb - antimony
for example:
133Sn + 7Li Sb+α+2n

3. Realistic shell model calculations around 132Sn
The realistic shell model calculations have opened a „new chapter” in nuclear structure physics. Parameter-free calculations around doubly-magic nuclides become possible. No adjustment of interaction is necessary to obtain the excellent agreement with the experimental data.
The nuclides from the vicinity of 132Sn and 208Pb provide the best data to test the experiment against theoretical predictions. However the experimental information is very sparse.
L. Coraggio, A. Covello, A. Gargano, N. Itaco, PRC 80, (R) (2009)

4. Available experimental information
The situation results from the inaccessibility of the region in standard fusion-evaporation or deep-inelastic reactions with stable projectiles and targets. What little is known comes mainly from beta-decay studies or spectroscopic investigations of fission products.
132Sb
L. Coraggio et. al. PRC 66, (2002)

5. The nuclei of interest will be populated in a reaction:
Cluster transfer reactions
The nuclei of interest will be populated in a reaction:
7Li(ASn,α2n)A+1Sb
Dasgupta et. al. PRC 66, (R) (2002)
There is a significant probability of a 7Li beam nucleus breaking up, with a triton being captured while α particle is emitted. Reaction offer access to states at relatively high angular momentum.
Clark et. al. [Cla] investigated the population of nuclei formed in reactions involving 7Li beams on targets of 160Gd and 184W.
cross-section for the (7Li,α2n) process at beam energies of a few MeV above Coulomb barrier is of order of 100 mb
exceeds by 1-2 orders of magnitude the predictions of a standard fusion-evaporation model
can be explained by using the Wilczynski binary transfer model + standard evaporation model.
[Cla] R. M. Clark et. al. PRC 72, (2005)
Fusion-evaporation
Incomplete fusion

6. Cluster transfer reactions
Recently, excited states in 123,125Sb with spins up to 23/2 have been studied following the 122,124Sn(7Li,α2n)123,125Sb incomplete fusion reaction at beam energy of 35, 37 MeV.
D. S. Judson et. al. PRC 76, (2007)
The (7Li,α2n) incomplete fusion reactions have been used to populate high-spin states in 121,123Sb [Wat] and in 179Hf [Mul].
[Wat] H. Watanabe et. al. PRC 79, (2009)
[Mul] S. M. Mullins et. al. PRC 61, (2000)
125Sb

7. 98Rb + 7Li 101-xSr+α+xn Spectroscopy of n-rich
Our REX-ISOLDE experiment
(November 2012)
Spectroscopy of n-rich
98-100Sr nuclei with 7Li(98Rb,axn) reaction at ≈ 3MeV/u
Spokepersons: S. Leoni and B. Fornal
98Rb + 7Li xSr+α+xn Rb 98 Sr 99
100
Collaboration: Univ. of Milan, IFJ PAN Kraków, SLCJ Warsaw, GANIL, LNL Legnaro, Univ. of Padova, K.U.Leuven, Université Libre de Bruxelles, CSNSM Orsay, Univ. of Köln, TU Darmstadt, TU Munchen, LPSC Grenoble, Argonne Nat. Lab., IFIN-HH Bucharest, IRNE-BAS Sofia, ISOLDE CERN.
133

8. REX-ISOLDE experiment
Cluster transfer reactions of radioactive beams 98Rb/98Sr on a on a 1.5 mg/cm2 thick LiF target [Bot]. Beam for 3 days.
Ebeam=2.85 MeV/A
I=2x104 pps
MINIBALL + T-REX setup
[Bot] S. Bottoni et. al. Acta Phys. Pol. 45 (2014)
α-transfer
t-transfer

9. α A+1Sb ASn 7Li A+1Sb* γ-rays 7Li target AGATA Recoil cone < 3o
Experimental setup
TRACE - Tracking Array for light charged particle ejectiles
Recoil cone < 3o
ASn beam
MeV α
A+1Sb
ASn
7Li
A+1Sb*
γ-rays
7Li target
AGATA

10. Details of an experiment
Beam energy: MeV
Target thickness: 1 mg/cm2
We assume :
100 mb for the (7Li,α2n) channel cross-section
50% efficiency of AGATA array triggered by charged particle detector
Element
particles/s
127Sn
8.16E+08
128Sn
6.36E+08
129Sn
3.50E+08
130Sn
1.58E+08
131Sn
6.83E+07
132Sn
3.11E+07
133Sn
2.76E+06
This gives:
Few thousands of gamma singles or double gamma coincidence events per second for Sn beam
For the reaction induced by the 131Sn beam leading to 132Sb recorded gamma-gamma events will be of the order of few hundreds per second
For a 133Sn beam we get one order of magnitude lower for the counting rate for 134Sb.

11. Advantages of the proposed experiment
The very inverse kinematics guarantees that the product nuclei all travel downstream in a very small recoil cone, thus Doppler correction do not require recoil detection.
Reaction channel of interest will be uniquely associated with the emission of an α particle.
The same reactions in their 7Li(ASn,pxn)ATe channel will also populate with appreciable yield the Te nuclei with A= The emitted protons may be used as event tags.
Presented counting rate estimates give us confidence that detailed gamma-ray spectroscopic studies of the low lying structures in Sb will be possible at SPES.