Mass and Spectroscopic Measurements in the Completed Mass-21 and -37 Isospin Quartets

Abstract

Low-lying $T=\frac{3}{2}$ levels of the mass-21 isospin quartet ($^{21}\mathrm{F}$, $^{21}\mathrm{Ne}$, $^{21}\mathrm{Na}$, and $^{21}\mathrm{Mg}$) and of three members of the mass-37 quartet ($^{37}\mathrm{Ar}$, $^{37}\mathrm{K}$, and $^{37}\mathrm{Ca}$) have been investigated. An improved particle-identification system which employs two transmission ($\ensuremath{\Delta}E$) detectors and one stopping ($E$) detector and which permits the measurement of low-yield nuclear reactions was used to determine the masses of the ${T}_{z}=\ensuremath{-}\frac{3}{2}$ nuclei $^{21}\mathrm{Mg}$ and $^{37}\mathrm{Ca}$ via the ($^{3}\mathrm{He}$, $^{6}\mathrm{He}$) reaction on $^{24}\mathrm{Mg}$ and $^{40}\mathrm{Ca}$ at ${E}_{^{4}\mathrm{He}}=56$ MeV. The complete experimental procedures followed in these three-neutron transfer investigations are discussed. The first three $T=\frac{3}{2}$ levels in $^{21}\mathrm{Ne}$ were established by a simultaneous study of the $^{22}\mathrm{Ne}(d, t)^{21}\mathrm{Ne}$ and $^{22}\mathrm{Ne}(d, ^{3}\mathrm{He})^{21}\mathrm{F}$ reactions at 39.6 MeV, while the $^{22}\mathrm{Na}(d, t)^{21}\mathrm{Na}$ reaction at 42 MeV was utilized to observe the lowest $T=\frac{3}{2}$ level in $^{21}\mathrm{Na}$. Excitation energies of the lowest $T=\frac{3}{2}$ levels in $^{37}\mathrm{K}$ and $^{37}\mathrm{Ar}$ were determined via the $^{39}\mathrm{K}(p, t)^{37}\mathrm{K}$ and $^{39}\mathrm{K}(p, ^{3}\mathrm{He})^{37}\mathrm{Ar}$ reactions induced by 45-MeV protons. Data from the complete quartets were used to test the isobaric-multiplet mass equation and the various predictions of the masses of neutron-deficient nuclei.