Neutron skin of $^{48}$Ca consistent with experimental data on skins


Abstract in English

[Background]: In our previous paper, we predicted $r_{rm skin}$, $r_{rm p}$, $r_{rm n}$, $r_{rm m}$ for $^{40-60,62,64}$Ca after determining the neutron dripline, using the Gogny-D1S HFB with and without the angular momentum projection (AMP). We found that effects of the AMP are small. Very lately, Tanaka {it et al.} measured interaction cross sections $sigma_{rm I}$ for $^{42-51}$Ca, determined $r_{rm m}$ from the $sigma_{rm I}$, and deduced skin $r_{rm skin}$ and $r_{rm n}$ from the $r_{rm m}$ and the $r_{rm p}(rm {exp})$ evaluated from the electron scattering. Comparing our results with the data, we find for $^{42-48}$Ca that GHFB and GHFB+AMP reproduce the data on $r_{rm skin}$, $r_{rm n}$, $r_{rm m}$, but not for $r_{rm p}(rm {exp})$. [Aim]: Our purpose is to determine a value of $r_{rm skin}^{48}$ by using GHFB+AMP and the constrained GHFB (cGHFB) in which the calculated value is fitted to $r_{rm p}(rm {exp})$. [Results]: For $^{42,44,46,48}$Ca, cGHFB hardly changes $r_{rm skin}$, $r_{rm m}$, $r_{rm n}$ calculated with GHFB+AMP, except for $r_{rm skin}^{48}$. For $r_{rm skin}^{48}$, the cGHFB result is $r_{rm skin}^{48}=0.190$fm, while $r_{rm skin}^{48}=0.159$fm for GHFB+AMP. We should take the upper and the lower bound of GHFB+AMP and cGHFB. The result $r_{rm skin}^{48}=0.159-0.190$fm consists with the $r_{rm skin}^{48}(sigma_{rm I})$ and the data $r_{rm skin}^{48}(rm $E1$pE)$ obtained from high-resolution $E1$ polarizability experiment ($E1$pE). Using the $r_{rm skin}^{48}$-$r_{rm skin}^{208}$ relation with strong correlation of Ref.[3], we transform the data $r_{rm skin}^{208}$ determined by PREX and $E1$pE to the corresponding values, $r_{rm skin}^{48}(rm tPREX)$ and $r_{rm skin}^{48}(rm t$E1$pE)$. Our result is consistent also for $r_{rm skin}^{48}(rm tPREX)$ and $r_{rm skin}^{48}(rm t$E1$pE)$.

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