Improved half-life determination and β-delayed γ -ray spectroscopy for 18Ne decay

The half-life of the superallowed Fermi β + emitter 18Ne has been determined to ±0.07% precision by counting 1042 keV delayed γ rays that follow approximately 8% of all β decays. The deduced half-life, T1/2 = 1.6648 (11) s, includes a 0.7%correction that accounts for systematic losses associated with rate-dependent detector pulse pileup that was determined using a recently developed γ -ray photopeak-counting technique. This result is a factor of two times more precise than, and in excellent agreement with, a previous lower-statistics measurement that employed the same experimental setup. High-resolution β-delayed γ -ray spectroscopy results for the relative γ -ray intensities and β-decay branching ratios to excited states in the daughter 18F are also presented.