Low-Lying Levels ofAr40

Seven excited levels of ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ have been populated by the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}(p,p^{\prime })$ reaction and studied with $\gamma -\gamma$ and $p^{\prime }-\gamma$ angular-correlation techniques. Spin-parity assignments are: 1461 keV, $2^{+}$; 2121 keV, $0^{+}$; 2524 keV, $2^{+}$; 2892 keV, ${\mathrm{}\left(4\right)\mathrm{}}^{+}$; 3207 keV, $2^{+}$ or $1^{\pm }$; 3507 keV, $2^{+}$ or $1^{+}$; 3681 keV, $3^{-}$. Multipole amplitude mixing ratios are: $2524\to 1461$-keV transition, $\delta \left(\frac{E2\mathrm{}}{M1\mathrm{}}\right)=+0.24\mathrm{}$; $3207\to 1461$-keV transition, if $2^{+}\to 2^{+}$, $\delta \left(\frac{E2\mathrm{}}{M1\mathrm{}}\right)=-0.20\mathrm{}$, and if $1^{\pm }\to 2^{+}$, $\delta =0\mathrm{}$. $\gamma$-ray branching ratios for the second to seventh excited levels have been measured. These results, together with lifetimes previously determined by others, are used to calculate $B\mathrm{}\left(E2\mathrm{}\right)\mathrm{}$ and $B\mathrm{}\left(M1\mathrm{}\right)\mathrm{}$ values which are compared with those of similar levels in ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ca}$.