The absolute differential cross sections for the reactions (A) ${}_{}{}^3{}_{}{}^{}\mathrm{H}$(${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^4{}_{}{}^{}\mathrm{He}$)${}_{}{}^2{}_{}{}^{}\mathrm{H}$ and (B) ${}_{}{}^3{}_{}{}^{}\mathrm{He}({}_{}{}^3{}_{}{}^{}\mathrm{He},{}_{}{}^4{}_{}{}^{}\mathrm{He})2p$ have been measured at 16.0 MeV c.m. Using final-state interaction theory, we have extracted the cross section for leaving the diproton in the ${}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ state for reaction (B). Conservation of isospin requires this cross section to have twice the magnitude and the same angular distribution as reaction (A). Isospin conservation also requires that reaction (A) be symmetric about 90° c.m. At 16.0 MeV c.m. we find deviations from 90° symmetry for reaction (A) which are consistent with lower-energy data. In addition, we report deviations from isospin conservation for the comparison test. However, using a simple single-nucleon-transfer model, we are able to qualitatively account both for the deviation from 90° c.m. symmetry for reaction (A) and for the deviation from the factor of 2 in the ratio of the yield of reaction (B) to that of reaction (A).

[NUCLEAR REACTIONS ${}_{}{}^3{}_{}{}^{}\mathrm{H}$(${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^4{}_{}{}^{}\mathrm{He}$)${}_{}{}^2{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{He}({}_{}{}^3{}_{}{}^{}\mathrm{He},{}_{}{}^4{}_{}{}^{}\mathrm{He})2p$ at 16 MeV c.m. Measured $\left(\frac{d\sigma }{d\Omega }\right)\left({\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}\right)$ and $\left(\frac{d^2\sigma }{d\Omega \mathrm{dE}}\right)\left({\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}\right)$. Test of isospin conservation.]

• Received 1 October 1973

DOI:https://doi.org/10.1103/PhysRevC.9.149