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arXiv · 2502.14106

Puzzling $B(E2;0^+\rightarrow 2^+)$ strength in the proton dripline nucleus $^{36}$Ca

Z. C. Xu·S. M. Wang·T. Beck·A. Gade·W. Nazarewicz
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Abstract

Recent measurements of the $E2$ transition rate from the ground state to the first 2$^+$ excited state of the proton dripline nucleus $^{36}$Ca show an unusual pattern when compared to its isotopic neighbor $^{38}$Ca: despite having a higher $E_x(2_1^+)$ excitation energy, the $B(E2; 0^+_1\rightarrow 2^+_1)$ rate in $^{36}$Ca is larger. The question that naturally arises is to what extent this observation can be attributed to the unbound character of the $2^+_1$ state. To understand the influence of the continuum space on the low-energy properties of $^{36}$Ca, we carried out Gamow shell model calculations that can account for the continuum coupling effects associated with the occupation of unbound $fp$ shells. We found that in the threshold $2^+$ state, $^{36}$Ca is spatially diffused, which impacts the observed $B(E2)$ trend.

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Z. C. Xu, S. M. Wang, T. Beck, A. Gade, W. Nazarewicz. 2025-02-19. Puzzling $B(E2;0^+\rightarrow 2^+)$ strength in the proton dripline nucleus $^{36}$Ca. https://doi.org/10.1103/wf6w-hczk

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