Precision half-life measurement of Al25

Abstract

A new precision half-life measurement of 25 Al was conducted using the TwinSol β-counting station at the University of Notre Dame. The new measured value of t new 1/2 = 7.1657(24) s is in good agreement with the most recent measurement, while being 3 times more precise. Using these new measurements, an evaluation of the 25 Al half-life has been performed, leading to an average halflife of t world 1/2 = 7.1665(26) s, which is 5 times more precise than it's predecessor and has a more satisfactory Birge ratio of 1.1. To aid in future measurements of correlation parameters, a new Fermi to Gamow-Teller mixing ratio ρ and correlation parameters for this mixed transition have been calculated assuming Standard Model validity using the new world half-life.

Resolving the discrepancy in the half-life of F20

“…The data analysis followed the well-established, widely used procedure outlined in [26], which was also used for previous half-life measurements using the β-counting station [23][24][25]. Data analysis was performed separately by Half-life two different group members.…”

“…The low energy of the primary beam was selected such that the production of additional radioactive species from the reaction of 19 F with the deuterium gas target was energetically forbidden. The 20 F lifetime was then determined using the same technique as for the 17 F [23], 25 Al [24], and 11 C [25] half-life measurements at the NSL; we therefore refer the reader to these publications for more explicit details on the experimental apparatus. After the production and separation of the radioactive beam using TwinSol, ions were implanted on a foil at the NSL β-counting station.…”

Precision half-life measurement of C11 : The most precise mirror transition Ft value

“…The data analysis followed the well-established procedure outlined in Ref. [31] as used previously in half-life measurements at the University of Notre Dame [24,25]. Each experimental run consisted of a single cycle containing a decay measurement and one or more cycles containing background measurements taken during implantation, which were then accounted for.…”

“…The measurement was then conducted following the procedure outlined in Refs. [24,25], with the primary beam turned off during the counting stage by deflecting it with a high voltage kicker upstream of the FN tandem Van de Graaff accelerator. 11 C was implanted in the tantalum foil for 60 minutes (approximately three half-lives), and then the foil was rotated into the counting position and the decay was measured.…”

“…Efforts are underway to expand this list, including measuring A β in 23 Mg using versatile ion-polarized techniques online (VITO) at ISOLDE [22] and a new ion trapping experiment under development at the Nuclear Science Laboratory (NSL) at the University of Notre Dame [23]. In parallel, a new high-precision half-life measurement program for superallowed T = 1/2 mixed mirror decays is also underway at the NSL [24,25].…”