"Enhanced E2 transition strength in 112,114Sn"
Rakesh Kumar, Inter University Accelerator Centre New Delhi INDIA
(id #21)
Seminar: YesPoster: No
Invited talk: No
R. Kumar,1 P. Doornenbal,2 A. Jhingan,1 R.K. Bhowmik,1 S. Muralithar,1 S. Appannababu,3
R. Garg,4 J. Gerl,5 M.Gόrska,5 J. Kaur,6 I. Kojouharov,5 S. Mandal,4 S. Mukherjee,3
D.Siwal,4 A. Sharma,7 Pushpendra P. Singh,8 R.P. Singh,1 and H.-J. Wollersheim 3
1IUAC, New Delhi 110067, India
2RIKEN , Saitama 351-0198, Japan
3 M.S.University of Baroda 390002, India
4 University of Delhi 110007, India
5GSI, Darmstadt, Germany
6 Panjab University 160014, India
7 Bareilly College 243005, India
8 INFN, Legnaro (PD) - Italy
In recent years the region of tin isotopes has been intensively investigated both from experimental and theoretical perspectives. In particular, the excitation energies and the reduced transition probabilities across the Z=50 chain has been examined in detail. This constitutes the longest shell-to-shell chain of semi-magic nuclei investigated in nuclear structure to date. Radioactive ion beams yield new experimental results close to the doubly-magic 100Sn and 132Sn, but very accurate data of the stable mid-shell nuclei are also of great relevance for our understanding of nuclear structure.
The experimental B(E2; 0+→ 2+) values, on the neutron-rich side of the Sn chain drop considerably with increasing neutron number and are well described by the seniority scheme. On the proton-rich side an almost constant plateau of high B(E2) values emerges. These unexpected high B(E2↑) values caused a persistent discrepancy between the results of the new large-scale shell model (LSSM) calculations and experiment findings.
The less known B(E2↑) values in 112Sn and 114Sn motivated two Coulomb excitation experiments to improve these crucial data points and to firmly establish the location along the Sn isotope chain where the B(E2↑) value is increased. At GSI [1] we performed two consecutive measurements using 114Sn and 116Sn beams on a 58Ni target. In the experiment carried out at IUAC [2], targets of 112Sn and 116Sn were bombarded with a 58Ni beam. The precise determination of the reduced transition probability, B(E2; 0+→ 2+), of 112Sn and 114Sn relative to well known E2 excitation strength in 116Sn was achieved by comparing the relative projectile to target 2+→ 0+ decay intensities. The obtained B(E2↑) values of 0.242(8) e2b2 and 0.232(8) e2b2 for 112Sn and 114Sn , respectively, confirms the tendency of large B(E2↑) values for light tin isotopes below the mid-shell 116Sn, that has been observed recently in various radioactive ion beam experiments.
A comparison with LSSM and relativistic quasiparticle random-phase approximation RQRPA [3] calculations will be presented.
[1] P. Doornenbal et al., Phys. Rev. C 78, 031303(R) (2008).
[2] R. Kumar et al., Phys. Rev. C 81, 024306 (2010).
[3] A. Ansari , Phys. Lett. B623, 37 (2005).
R. Garg,4 J. Gerl,5 M.Gόrska,5 J. Kaur,6 I. Kojouharov,5 S. Mandal,4 S. Mukherjee,3
D.Siwal,4 A. Sharma,7 Pushpendra P. Singh,8 R.P. Singh,1 and H.-J. Wollersheim 3
1IUAC, New Delhi 110067, India
2RIKEN , Saitama 351-0198, Japan
3 M.S.University of Baroda 390002, India
4 University of Delhi 110007, India
5GSI, Darmstadt, Germany
6 Panjab University 160014, India
7 Bareilly College 243005, India
8 INFN, Legnaro (PD) - Italy
In recent years the region of tin isotopes has been intensively investigated both from experimental and theoretical perspectives. In particular, the excitation energies and the reduced transition probabilities across the Z=50 chain has been examined in detail. This constitutes the longest shell-to-shell chain of semi-magic nuclei investigated in nuclear structure to date. Radioactive ion beams yield new experimental results close to the doubly-magic 100Sn and 132Sn, but very accurate data of the stable mid-shell nuclei are also of great relevance for our understanding of nuclear structure.
The experimental B(E2; 0+→ 2+) values, on the neutron-rich side of the Sn chain drop considerably with increasing neutron number and are well described by the seniority scheme. On the proton-rich side an almost constant plateau of high B(E2) values emerges. These unexpected high B(E2↑) values caused a persistent discrepancy between the results of the new large-scale shell model (LSSM) calculations and experiment findings.
The less known B(E2↑) values in 112Sn and 114Sn motivated two Coulomb excitation experiments to improve these crucial data points and to firmly establish the location along the Sn isotope chain where the B(E2↑) value is increased. At GSI [1] we performed two consecutive measurements using 114Sn and 116Sn beams on a 58Ni target. In the experiment carried out at IUAC [2], targets of 112Sn and 116Sn were bombarded with a 58Ni beam. The precise determination of the reduced transition probability, B(E2; 0+→ 2+), of 112Sn and 114Sn relative to well known E2 excitation strength in 116Sn was achieved by comparing the relative projectile to target 2+→ 0+ decay intensities. The obtained B(E2↑) values of 0.242(8) e2b2 and 0.232(8) e2b2 for 112Sn and 114Sn , respectively, confirms the tendency of large B(E2↑) values for light tin isotopes below the mid-shell 116Sn, that has been observed recently in various radioactive ion beam experiments.
A comparison with LSSM and relativistic quasiparticle random-phase approximation RQRPA [3] calculations will be presented.
[1] P. Doornenbal et al., Phys. Rev. C 78, 031303(R) (2008).
[2] R. Kumar et al., Phys. Rev. C 81, 024306 (2010).
[3] A. Ansari , Phys. Lett. B623, 37 (2005).
