Lifetimes of theN145.83-MeV and 6.44-MeV Levels

Abstract

The lifetimes of the ${\mathrm{N}}^{14}$ 5.83- and 6.44-MeV levels were studied by the Doppler shift attenuation method using the ${\mathrm{C}}^{12}({\mathrm{He}}^3, p){\mathrm{N}}^{14}$ reaction to populate the levels. The shifts in energy of the 0.73-MeV 5.83→5.10 transition and the 1.33-MeV 6.44→5.10 transition were observed between two angles to the beam by recording gamma-ray spectra in coincidence with the ${\mathrm{N}}^{14}$ 5.10→0 transition. From these measurements the mean lifetime of the ${\mathrm{N}}^{14}$ 5.83-MeV level was found to be greater than 2.3×${10}^{-12\mathrm{}}$ sec, while the mean lifetime of the ${\mathrm{N}}^{14}$ 6.44-MeV level was found to be (5.9±1.2)×${10}^{-13\mathrm{}}$ sec.