Doppler-shift attenuation lifetimes inN14derived from experimental stopping parameters

Abstract

The lifetime values of 105 ± 15, 8.4 ± 0.4 16 ± 8, and 185 ± 15 fs for the 2313, 3948, 5690, and 6204 keV levels of ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$, respectively, were measured using the Doppler-shift attenuation method through the ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}(p,\gamma ){}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ reaction at $E_p=1150\mathrm{}$ keV. For the Doppler-shift attenuation analysis the correction factors of the nuclear and electronic stopping powers were determined by measuring Doppler-shift attenuation and line shape of $\gamma$ rays from the 6204→2313 keV transition and by measuring range values of the 20, 40, 60, 80, and 100 keV ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ nuclei. The two most commonly used scattering potentials, i.e., Thomas-Fermi and Lenz-Jensen, were used in the estimation of the correction factors and $F\left(\tau \right)$ curves. Both potentials were shown to give the same lifetimes. All calculations were done by the Monte Carlo method. The accuracy of the results and the transition rates in the frame of a weak coupling model are discussed.