Angular correlations in the reactions C¹²(He³, αγ)C¹¹ and C¹²(He³, pγ)N¹⁴

Abstract

Particle-gamma angular correlations in which the particles were detected at 180° to the beam direction have been studied. It is shown that the 2.00 MeV level in C¹¹ is likely to have spin $\text{1}\text{2}$, though spins of $\text{3}\text{2}$ or $\text{5}\text{2}$ with restricted values of the quadrupole-dipole amplitude ratios are also allowed. The spin of the 5.10 MeV state in N¹⁴ is shown to be 2 and the transition to the ground state to contain E1, M2 and E3 components. The amplitudes of the quadrupole and octupole components relative to that of the dipole are −0.18±.03 and 0.12±0.04 respectively. The phase convention of Devons and Goldfarb is used. The correlation through the 4.91 MeV state of N¹⁴ is found to be consistent with isotropy and the intensity of decays to the 0⁺ state at 2.31 MeV and to the 3.95 MeV state are shown to be (0.4±0.7)% and (1.3±1.0)% of that to the ground state. These results are consistent with the expected spin of zero for the 4.19 MeV state, spin one is unlikely but spin two is still possible.