Disintegration of Hyperfragments. III

The systematic study of hyperfragments using nuclear emulsion, which has been reported on in two previous papers, has been continued. Examples of ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{H}_{}^4{}_{}{}^{}$, ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{He}$, and ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{Li}$ hyperfragments are reported here. ${\Lambda }^0$ particle binding energies previously reported have been corrected according to the latest range-energy data of Barkas et al. Average values found for the binding energy $B_{\Lambda }$ are: ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{H}_{}^3{}_{}{}^{}(B_{\Lambda }=-0.3\mathrm{}\pm 0.4 \mathrm{Mev}); {}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{H}_{}^4{}_{}{}^{}(B_{\Lambda }=1.8\mathrm{}\pm 0.4 \mathrm{Mev});$ ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{He}_{}^4{}_{}{}^{}(B_{\Lambda }=1.9\mathrm{}\pm 0.4 \mathrm{Mev}); {}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{He}_{}^5{}_{}{}^{}(B_{\Lambda }=1.6\mathrm{}\pm 0.6 \mathrm{Mev});$ ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{Li}_{}^6{}_{}{}^{}(B_{\Lambda }=6.8\mathrm{}\pm 3.0 \mathrm{Mev}); {}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{Li}_{}^6{}_{}{}^{} or {}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{Li}_{}^7{}_{}{}^{}(B_{\Lambda }=5.2\mathrm{} or 5.0\pm 2.5 \mathrm{Mev});$ ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{Li}_{}^7{}_{}{}^{} or {}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{Li}_{}^8{}_{}{}^{}(B_{\Lambda }=5.1\mathrm{}\pm 0.6 \mathrm{Mev}); {}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{Be}_{}^8{}_{}{}^{}(B_{\Lambda }=5.1\mathrm{}\pm 4.0 \mathrm{Mev});$ ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{Be}_{}^9{}_{}{}^{}(B_{\Lambda }=6.2\mathrm{}\pm 0.6 \mathrm{Mev}); {}_{\Lambda }{}^{}{}_{}{}^{}C_{}^{11}{}_{}{}^{}(B_{\Lambda }=13\mathrm{}\pm 6 \mathrm{Mev}).\mathrm{}$ The absence of ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{H}_{}^2{}_{}{}^{}$ indicates the ${\Lambda }^0$-nucleon system does not have a bound state. The absence of ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{He}_{}^3{}_{}{}^{}$ implies that ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{H}_{}^3{}_{}{}^{}$ is an isotopic spin singlet. The agreement in the binding energies of ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{H}_{}^4{}_{}{}^{}$ and ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{He}_{}^4{}_{}{}^{}$ supports the hypothesis of charge independence for ${\Lambda }^0$-nucleon forces. The ratios of nonmesonic to mesonic decays of hyperfragments $Q^{\mathrm{}(-)\mathrm{}}$, as defined by Ruderman and Karplus, are found to be: for hydrogen hyperfragments $Q^{\mathrm{}(-)\mathrm{}}=0\mathrm{}$; for helium $Q^{\mathrm{}(-)\mathrm{}}=1.5\mathrm{}$; for hyperfragments of $Z>~3$, $Q^{\mathrm{}(-)\mathrm{}}=43\mathrm{}$. According to the analysis of Ruderman and Karplus these values suggest that the ${\Lambda }^0$ particle decays into an angular momentum state of $l=0\mathrm{}$ or $l=1\mathrm{}$, and hence that the spin of the ${\Lambda }^0$ is either ½ or $\frac{3}{2}$. In the case of hyperfragments which decay into a proton, ${\pi }^{-}$ meson, and a recoil, the angle ${\theta }_{\Lambda \pi }$ between the ${\pi }^{-}$-meson direction in the ${\Lambda }^0$ rest frame and the direction of motion of the ${\Lambda }^0$ within the hyperfragment can be measured, if it is assumed that the interaction of the decay particles is negligible. The distribution of these angles shows a peaking in the forward and backward directions. This is suggestive of a spin greater than ½ for the ${\Lambda }^0$.