ReactionS36(p,γ)Cl37and Properties ofCl37

The ${\mathrm{S}}^{36}(p,\gamma ){\mathrm{Cl}}^{37}$ reaction has been studied in the range $E_p=800-1940\mathrm{}$ keV in order to determine properties of excited states of ${\mathrm{Cl}}^{37}$. Over 80 narrow resonances due to this reaction were identified and located in proton energy with an accuracy of ±3 keV. The observed resonance strengths $\frac{(2\mathrm{}{J}_r+1){\Gamma }_{\gamma }{\Gamma }_p}{\Gamma }$ vary between 0.1 and 6.3 eV, with the exception of the outstanding resonance at 1887±2 keV, which has a strength of 130±20 eV. The general behavior of the average resonance strength as a function of proton energy is in agreement with predictions based upon well-known approximate relationships between the level density and the radiative and proton widths ${\Gamma }_{\gamma }$ and ${\Gamma }_p$. Detailed studies of the $\gamma$-ray decay schemes of resonances at $E_p=940,969\mathrm{} \left(\mathrm{doublet}\right),983,1079, \mathrm{and} 1120$ keV with large NaI (Tl) and Ge(Li) detectors provide evidence for previously unreported levels in ${\mathrm{Cl}}^{37}$ at $E_x=3.62,3.74, \mathrm{and} \mathrm{}\left(4.4\right)\mathrm{}$ MeV. All of the new bound levels decay to the ground state. No evidence was found for a possible level in ${\mathrm{Cl}}^{37}$ near 0.8 MeV. Spin assignments for each of the resonances listed above were derived from $\gamma$-ray angular-correlation measurements. The 1887-keV resonance ($E_x=10.22\mathrm{}$ MeV) decays predominantly to the 3.105-MeV level. The resonance and 3.105-MeV levels are each shown to have $J^{\pi }={\frac{7}{2}}^{-}$ and to exhibit other expected properties of the $T=\frac{5}{2}$ and $T=\frac{3}{2}$ members of the $1f_{\frac{7}{2}}$ single-nucleon configuration. The resonance is identified as the analog of the ${\mathrm{S}}^{37}$ ground state. The $3.105\left({\frac{7}{2}}^{-}\right)\to \left({\frac{3}{2}}^{+}\right)$ transition is mixed $E3\mathrm{}-M2\mathrm{}$ with $\delta =-0.18\mathrm{}\pm 0.01$. The resonance→ 3.105 transition is pure $M1\mathrm{}$ with an observed strength of 1.7±0.3 Weisskopf units, in excellent agreement with a calculated value of 1.6 Weisskopf units for a $(1\mathrm{}{f}_{\frac{7}{2}},T=\frac{5}{2})\to (1\mathrm{}{f}_{\frac{7}{2}},T=\frac{3}{2})$ transition. A ${\mathrm{S}}^{36}(p,\gamma ){\mathrm{Cl}}^{37}$ reaction $Q$ value of 8.382±0.008 MeV was determined from Ge(Li) spectra.