High-precision half-life measurements of theT=1/2mirrorβdecaysF17andCl33
Physical Review C
Measurements of the f t values for T = 1/2 mirror β + decays offer a method to test the conserved vector current hypothesis and to determine V ud , the up-down matrix element of the Cabibbo-Kobayashi-Maskawa matrix. In most mirror decays used for these tests, uncertainties in the f t values are dominated by the uncertainties in the half-lives. Purpose: Two precision half-life measurements were performed for the T = 1/2 β + emitters, 17 F and 33 Cl, in order to eliminate the half-life as the
... alf-life as the leading source of uncertainty in their f t values. Method: Half-lives of 17 F and 33 Cl were determined using β counting of implanted radioactive ion beam samples on a moving tape transport system at the Système de Production d'Ions Radioactifs Accélérés en Ligne low-energy identification station at the Grand Accélérateur National d'Ions Lourds. Results: The 17 F half-life result, 64.347 (35) s, precise to ±0.05%, is a factor of 5 times more precise than the previous world average. The half-life of 33 Cl was determined to be 2.5038 (22) s. The current precision of ±0.09% is nearly 2 times more precise compared to the previous world average. Conclusions: The precision achieved during the present measurements implies that the half-life no longer dominates the uncertainty of the f t values for both T = 1/2 mirror decays 17 F and 33 Cl.