Precise half-life measurements for the superallowed beta(+) emitters Ar-34 and Cl-34 Academic Article uri icon


  • To contribute meaningfully to any test of the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, the measured ft value of a superallowed 0+0+ + transition must be obtained to a precision of 0.1% or better. We have determined the half-life of the superallowed emitter Ar34 to be 843.8(4)ms; the quoted precision, 0.05%, is a factor of five improvement on the best previous measurement and meets this demanding requirement. Our measurement employed a high-efficiency gas counter, which was sensitive to positrons from both Ar34 and its daughter Cl34. We achieved the required precision on Ar34 by analyzing the parent-daughter composite decay with a new fitting technique. We also obtained an improved half-life for Cl34 of 1.5268(5) s, which has 0.03% precision and is a factor of two improvement on previous results. As a by-product of these measurements, we determined the half-life of Ar35 to be 1.7754(11) s. 2006 The American Physical Society.

published proceedings


author list (cited authors)

  • Iacob, V. E., Hardy, J. C., Brinkley, J. F., Gagliardi, C. A., Mayes, V. E., Nica, N., ... Tribble, R. E.

citation count

  • 29

complete list of authors

  • Iacob, VE||Hardy, JC||Brinkley, JF||Gagliardi, CA||Mayes, VE||Nica, N||Sanchez-Vega, M||Tabacaru, G||Trache, L||Tribble, RE

publication date

  • November 2006