New Lifetime Measurement For The 2(1)(+) Level In Sn-112 By The Doppler-Shift Attenuation Method

Levels in the Sn-112 nucleus have been excited by inelastic scattering with Cl-35 projectile at E-lab = 195 MeV. The Doppler affected gamma-ray peak arising from the decay of the 2(1)(+) level has been analyzed, using updated methodologies, to extract the level lifetime and corresponding electric quadrupole (E2) transition probability, B(E2; 0(g.s.)(+) -> 2(1)(+)). The present result is discrepant with respect to the results reported from existing lifetime measurements, but in compliance with independent systematic measurements of the low-lying E2 transition strengths in the stable even-mass Sn isotopes, by pure Coulomb excitation as well as heavy-ion induced inelastic collisions. The transition probability also confirms an enhancement in collectivity for the 2(1)(+) level, and is found to be in good agreement with generalized seniority model (GSM) as well as state-of-the-art Monte Carlo shell model (MCSM) calculations. Within the realm of the MCSM scheme, the enhancement is understood in terms of oblate deformations for both the 0(g.s.)(+) and 2(1)(+) states in Sn-112 arising due to strong proton-core excitations and enhanced proton-neutron interactions. In addition, limits for the lifetime of the 3(1)(-) level and the E1 transition probability, B(E1; 3(1)(-) -> 2(1)(+)), have been obtained.