Evidence for reduced collectivity around the neutron mid-shell in the stable even-mass Sn isotopes from new lifetime measurements

Jungclaus, A.; Walker, J.; Leske, J.; Speidel, K.-H.; Stuchbery, Andrew; East, Michael; Boutachkov, P.; Cederkall, J.; Doornenbal, P.; Egido, J.L.; Ekstrom, A.; Gerl, J; Gernhauser, R.; Goel, N.; Gorska, M; Kojouharov, I; Maier-Komor, P; Modamio, V.; Naqvi, F.; Pietralla, N.; Pietri, S.; Prokopowicz, W.; Schaffner, H.; Schwengner, R.; Wollersheim, H.J.

Evidence for reduced collectivity around the neutron mid-shell in the stable even-mass Sn isotopes from new lifetime measurements

Date

2011

Authors

Jungclaus, A.

Walker, J.

Leske, J.

Speidel, K.-H.

Stuchbery, Andrew

East, Michael

Boutachkov, P.

Cederkall, J.

Doornenbal, P.

Egido, J.L.

Publisher

Elsevier

Abstract

Precise measurements of the lifetimes of the first excited 2+ states in the stable even-A Sn isotopes112-124Sn have been performed using the Doppler shift attenuation technique. For the isotopes112Sn,114Sn and116Sn the E2 transition strengths deduced from the measured lifetimes are in disagreement with the previously reported values and indicate a shallow minimum at N=66. The observed deviation from a maximum at mid-shell is attributed to the obstructive effect of the s1/2 neutron orbital in generating collectivity when near the Fermi level.