High-precision half-life measurements for the superallowed Fermi [beta][superscript +] emitter [superscript 14]O

Abstract

The half-life of the superallowed Fermi [beta][superscript +] emitter [superscript 14]O has been determined via simultaneous direct [beta] and [gamma] counting experiments at TRIUMF’s Isotope Separator and Accelerator (ISAC) facility. A [gamma]-ray counting measurement was performed by detecting the 2312.6-keV [gamma] rays emitted from an excited state of the daughter [superscript 14]N following the implantation of samples at the center of the 8[pi] [gamma]-ray spectrometer, a spherical array of 20 high-purity germanium (HPGe) detectors. A simultaneous [beta] counting experiment was performed using a fast plastic scintillator positioned behind the implantation site with a solid angle coverage of ∼20%. The results, T[subscript 1/2]([beta]) = 70.610 [plus or minus] 0.030 s and T[subscript 1/2]([gamma]) = 70.632 [plus or minus] 0.094 s, form a consistent set and, together with eight previous measurements, establish a new average for the [superscript 14]O half-life of T[subscript 1/2] = 70.619 [plus or minus] 0.011 s with a reduced X[superscript 2] of 0.99.