Speaker
Description
The experimental B(E2) values in light even-even Sn isotopes are found to be enhanced compared to theory, a discrepancy which has eluded a satisfactory solution for over a decade. For further examination, supplementary information such as spectroscopic quadrupole moments ($Q_s$) are needed.
A safe-energy Coulomb excitation of $^{110}$Sn was conducted at HIE-ISOLDE, CERN. The $^{110}$Sn beam was accelerated to 4.4 MeV per nucleon and Coulomb excited on a 4-mg/cm$^2$ $^{206}$Pb target. Gamma rays from the beam and target nuclei were detected with the Miniball HPGe spectrometer.
The $Q_s(2_1^+)$ of $^{110}$Sn was newly determined with a preliminary value of $+0.22^{+0.08}_{−0.06}$ eb. Both the sign and the magnitude of $Q(2_1^+)$ are in agreement with the Monte Carlo shell model prediction of an oblate shape for the $2_1^+$ state in $^{110}$Sn [1]. Independent lifetime measurements of the $2_1^+$ and $4_1^+$ states were also performed with simulations. The preliminary $B(E2\uparrow)$ value of our work is 0.236(17) e$^2$b$^2$, consistent with previous experiments [2-4] but with a higher precision. A preliminary $B(E2\downarrow)$ value of the $4_1^+$ state was determined as $200^{+50}_{−70}$ e$^2$fm$^4$. This B(E2) value suggests an enhanced pairing force in light Sn isotopes [5]. Details on the new and improved spectroscopic results will be presented and compared to theory.
[1] T. Togashi et al., Phys. Rev. Lett. 121, 052601 (2018).
[2] J. Cederkäll et al., Phys. Rev. Lett. 98, 172501 (2007).
[3] C. Vaman et al., Phys. Rev. Lett. 99, 162501 (2007).
[4] G. J. Kumbartzki et al., Phys. Rev. C 93, 044316 (2016).
[5] A. P. Zuker, Phys. Rev. C 103, 024322 (2021).
| Email Address | jcpark@ibs.re.kr |
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