Low-lying transition strengths in the neutron-deficient Te-isotopes
Poster presented at IV International Conference on Nuclear Structure and Dynamics (NSD 2019) in Venice on May 13-17, 2019
An enhancement of the B(E2, 21+ RT 01+) and unexpectedly low B(E2, 41+ RT 21+) values was found in 50Sn isotopes below mid-shell. However, the puzzling B(E2, 21+ RT 01+) systematics around N = 60 was understood very recently in state-of-the-art Monte Carlo shell model calculations [T. Togashi et al., Phys. Rev. Lett. 121, 062501 (2018)] by activating protons in the 1g9/2 orbit and a second-order quantum phase transition from the moderately derformed phase to the pairing (seniority) phase that occurs around N = 66. But a sharp drop of the B(E2, 41+ RT 21+) values below N = 66 leading to unusual small B4̷ 2=B(E2, 41+ RT 21+)/B(E2, 21+ RT 01+) ratios is not understood so far. In neighboring 52Te isotopes a simular situation seems to be present, where especially data on B(E2, 41+ RT 21+) values are lacking that would allow a clear conclusion. An exclusive data point for the neutron-deficient Te isotopes with N < 66 also shows a low B4̷ 2 ratio in ¹¹4Te and is a conundrum [O. Möller et al., Phys. Rev. C 71, 064324 (2005)]. In this framework ¹¹²Te,¹¹6Te represent interesting cases as it is just at the edge of the shape transition observed in neighboring Sn isotopes and is also supported by experimental data on ¹¹4Te. Therefore, we determined B(E2) values between the lowest states in ¹¹²Te,¹¹6Te from level lifetimes measured with the recoil distance Dopplershift method (RDDS). We will present these results and relate them both to the systematics along the Te isotopic chain and to the interpretation of the Sn isotopes.