Structure of Cl38 and the quest for a comprehensive shell model interaction

The higher-spin structure of ³⁸Cl ($N=21$) was investigated following the ²⁶Mg(¹⁴C, $pn$) reaction at 30 and 37 MeV beam energies. The outgoing protons were detected in an $E-\text{Δ}E$ Si telescope placed at 0° close to the target with a Ta beam stopper between the target and telescope. Multiple $\text{γ}$ rays were detected in time coincidence with the protons using an enhanced version of the FSU $\text{γ}$-detection array. The level scheme was extended up to 8420 keV with a likely spin of 10 $\text{ℏ}$. A new multishell interaction was developed guided by the experimental information. This FSU interaction was built by fitting to the energies of 270 experimental states from ¹³C to ⁵¹Ti. Calculations using the FSU interaction reproduce observed properties of ³⁸Cl rather well, including the spectroscopic factors. The interaction has been successfully used to interpret the 1p1h and 2p2h configurations in some nearby nuclei as well.