Quadrupole-Dipole Mixture of theN143.95 → 0 Gamma-Ray Transition

The quadrupole-dipole mixing ratio of the 4% gamma-ray branch from the ${\mathrm{N}}^{14}$ second excited state at 3.95 MeV to the ground state has been determined using the ${\mathrm{C}}^{12}({\mathrm{He}}^3, p){\mathrm{N}}^{14}$ reaction and an ${\mathrm{He}}^3$ beam of 5 MeV. Gamma rays due to the decay of the 3.95-MeV level were detected in coincidence with protons of the right energy to populate the 3.95-MeV level. The protons were detected in a surface-barrier counter at 0° with respect to the ${\mathrm{He}}^3$ beam, and the populations of the magnetic substates were fixed from a simultaneous observation of the transition to the $0^{+}$, 2.31-MeV level. Two regions of values for the mixing ratio $x$ consistent with the experiment were found, namely, $-0.5\mathrm{}\le x\le -0.2\mathrm{}$ and $-5\mathrm{}\le x\le -2\mathrm{}$.