Properties ofCl37Levels and the System of72−Analog and Antianalog Levels inA=35and 37 Nuclei

The $\gamma$-ray decay properties of the $J^{\pi }$, $T={\frac{7}{2}}^{-},\frac{5}{2}$ analog of the ground state of ${\mathrm{S}}^{37}$, observed previously at $E_p=1887\mathrm{}$ keV in the ${\mathrm{S}}^{36}(p,\gamma ){\mathrm{Cl}}^{37}$ reaction, have been reexamined. Transitions to previously unobserved levels in ${\mathrm{Cl}}^{37}$ at $E_x=4.811\mathrm{} \mathrm{and} 5.574$ MeV were found in addition to the known strong $M1\mathrm{}$ transition to the $J^{\pi }$, $T={\frac{7}{2}}^{-},\frac{3}{2}$ antianalog state at $E_x=3.105\mathrm{}$ MeV. Other weak transitions suggest the presence of levels at $E_x=3.911\mathrm{} \mathrm{and} 6.482$ MeV. The data are consistent with a hypothesis that the 4.811- and 5.574-MeV levels, and possibly the other two suggested levels, are members of the group of ${\frac{7}{2}}^{-}$, $T=\frac{3}{2}$ configuration states expected from fragmentation of the antianalog state by spin and isospin recoupling of the ${d_{\frac{3}{2}}}^4$ nucleon group in $A=37\mathrm{}$. Detailed analysis of the strengths of the analog $M1\mathrm{}$ and Gamow-Teller $\beta$ decays to the 3.105-MeV level, and of the $M1\mathrm{}-E2\mathrm{}$ and $M2\mathrm{}-E3\mathrm{}$ mixing ratios, yields information on the wave function of the antianalog state and a prediction of the mean life of this level. A similar analysis of the ${\frac{7}{2}}^{-}$ parent, analog, and antianalog system in $A=35\mathrm{}$ is performed and the results are presented. In both the $A=35\mathrm{} \mathrm{and} 37$ systems, recoupling in the ${d_{\frac{3}{2}}}^n$ nucleon group appears necessary to explain the data. Additional information on ${\mathrm{Cl}}^{37}$ levels obtained from measurements at the analog resonance, and at the $E_p=1147\mathrm{}$-keV resonance, include the more accurate value $Q=8384.5\mathrm{}\pm 1.5$ keV for the ${\mathrm{S}}^{36}(p,\gamma ){\mathrm{Cl}}^{37}$ reaction, the energies 1.723 ± 0.002 and 3.1048 ± 0.0005 MeV for the first and third excited states, and the mean life ${\tau }_m={0.17}_{-0.05\mathrm{}}^{+0.09\mathrm{}} \mathrm{and} >~1.0$ psec for the 1.723- and 3.105-MeV levels, respectively. The results of angular-correlation measurements at the 1147-keV resonance are consistent with earlier assignments of $J=\frac{1}{2}$ for the 1.723-MeV level. The results are compared with recent shell-model calculations involving ${d_{\frac{3}{2}}}^n{f}_{\frac{7}{2}}$ and ${d_{\frac{3}{2}}}^n{p}_{\frac{3}{2}}$ configurations. The observed $M2\mathrm{}$ transition rates are successfully explained using bare-nucleon $g$ factors when recoupling of the ${d_{\frac{3}{2}}}^n$ group is considered.