Nuclear Charge Radius of $^{12}$Be

TL;DR

This study precisely measured the nuclear charge radius of $^{12}$Be using collinear laser spectroscopy, revealing a breakdown of the N=8 shell closure and highlighting the sensitivity of the radius to nuclear structure.

Contribution

The paper provides the first precise measurement of $^{12}$Be's charge radius and compares it with theoretical models, indicating shell closure breakdown.

Findings

Charge radius increases from $^{10}$Be to $^{12}$Be.

Experimental data supports shell closure breakdown at N=8.

Charge radius sensitive to nuclear structure variations.

Abstract

The nuclear charge radius of $^{12}$Be was precisely determined using the technique of collinear laser spectroscopy on the $2s_{1/2}\rightarrow 2p_{1/2, 3/2}$ transition in the Be$^{+}$ ion. The mean square charge radius increases from $^{10}$Be to $^{12}$Be by $\delta <r_{\rm c}^2>^{10,12} = 0.69(5) \fm^{2}$ compared to $\delta <r_{\rm c}^2>^{10,11} = 0.49(5) \fm^{2}$ for the one-neutron halo isotope $^{11}$Be. Calculations in the fermionic molecular dynamics approach show a strong sensitivity of the charge radius to the structure of $^{12}$Be. The experimental charge radius is consistent with a breakdown of the N=8 shell closure.