TY  - JOUR
AU  - Cederkall, J.
AU  - Fahlander, C.
AU  - Golubev, P.
AU  - Knyazev, A.
AU  - Iwanicki, J.
AU  - Wrzosek-Lipska, K.
AU  - Blazhev, A.
AU  - Reiter, P.
AU  - Rosiak, D.
AU  - Seidlitz, M.
AU  - Warr, N.
AU  - Butler, P. A.
AU  - Gaffney, L. P.
AU  - Berry, T.
AU  - Cox, D. M.
AU  - Pakarinen, J.
AU  - Kröll, Th.
AU  - Henrich, C.
AU  - Schilling, M.
AU  - Stahl, C.
AU  - von Schmid, M.
AU  - Rainovski, G.
AU  - Berger, C.
AU  - Berner, C.
AU  - Gernhäuser, R.
AU  - Illana, A.
AU  - De Witte, H.
AU  - Górska, M.
AU  - Habermann, T.
AU  - Saha, S.
AU  - de Angelis, G.
AU  - Borge, M. J. G.
AU  - Tengblad, O.
AU  - Otsuka, T.
AU  - Tsunoda, Y.
TI  - First Measurement of the Quadrupole Moment of the 2<sub>1</sub><sup>+</sup> State in <sup>110</sup>Sn 
JO  - Physical review letters
VL  - 135
IS  - 22
SN  - 0031-9007
CY  - College Park, Md.
PB  - APS
M1  - GSI-2026-00246
SP  - 222502
PY  - 2025
N1  - Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license.
AB  - The Sn isotopic chain, exhibiting double shell closures at  100 Sn   and  132 Sn  , is a key testing ground for theoretical models of the atomic nucleus. It was originally predicted that the transitional matrix elements between the first 2+ state and the 0+ ground state for the even-even isotopes in this chain should show a simple dependence on the neutron number. This prediction was, however, disproven experimentally in some of the first experiments with postaccelerated radioactive beams, a situation that has remained unresolved ever since. Subsequent theoretical work has suggested that the explanation can be found in proton excitations across the 𝑍 =50 shell gap, with an accompanying experimental signature that the first excited 2+ state in  110 Sn   should have a distinct oblate shape. In this Letter, we present the first measurements of the spectroscopic quadrupole moment of the 2+1 state, 𝐵⁡(𝐸⁢2;4+1→2+1) and 𝐵⁡(𝐸⁢2;4+2→2+1) values for  110 Sn  , as well as the 𝐵⁡(𝐸⁢2;2+1→0+1) value with significantly improved precision compared to previous results. From the same experiment, half-lives of the 2+1 and 4+1 states were measured using the Doppler shift attenuation method. Our combined result, 𝑄⁡(2+1)=20⁢(8)  efm2 for  110 Sn  , is the largest positive value known among the Sn isotopes, indicating an oblate shape of the state by more than 2⁢𝜎. Comparison of the 𝐸⁢2 transition strengths and quadrupole moments with recent shell model calculations are presented.
LB  - PUB:(DE-HGF)16
DO  - DOI:10.1103/7ysn-8y1w
UR  - https://repository.gsi.de/record/364066
ER  -