Studies of Electromagnetic Transitions in N14 by Means of the C12(He3, p)N14 Reaction

Abstract

The electromagnetic decays of the ${\mathrm{N}}^{14}$ states between 5 and 6.5 MeV were studied using the ${\mathrm{C}}^{12}({\mathrm{He}}^3, p){\mathrm{N}}^{14}$ reaction. From investigations of the gamma-ray spectra on and off the 3.0-MeV resonance for production of the ${\mathrm{N}}^{14}$ 6.44-MeV level, this state was found to decay to the ground, 3.95-, and 5.10-MeV levels of ${\mathrm{N}}^{14}$ with branching ratios of (65±3%), (21±2)%, (14±3)%, respectively. From a study of the internal pairs corresponding to the 6.21 → 2.31 transition, this transition was shown to be predominantly $M1\mathrm{}$ so that the ${\mathrm{N}}^{14}$ 6.21-MeV level has even parity. Similarly, it was confirmed that the ${\mathrm{N}}^{14}$ 6.44 → 0 transition is predominantly $E2\mathrm{}$. The angular distributions of the gamma rays from ${\mathrm{C}}^{12}$+${\mathrm{He}}^3$ at $E_{{\mathrm{He}}^3}=2.75\mathrm{}$ MeV were measured. It was shown that the mixing parameter $x$ (amplitude ratio of quadrupole to dipole radiation) for the 5.69 → 0 transition is $x=+0.03\mathrm{}\pm 0.03$ and for the 5.10 → 0 transition $x=-0.12\mathrm{}\pm 0.03$. The branching ratios of the ${\mathrm{N}}^{14}$ 5.10-, 5.69-, and 6.21-MeV levels to the ${\mathrm{N}}^{14}$ ground state and 2.31-MeV first excited state were measured. The results are in satisfactory agreement with previous determinations.