Beta Decay of S38

G. A. P. Engelbertink and J. W. Olness
Phys. Rev. C 3, 180 – Published 1 January 1971
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Abstract

The β decay of S38 to states of Cl38 has been studied with Si, Ge(Li), and NaI(Tl) detectors. S38 was produced in the reaction S36(t,p)S38 at Et=3.26 MeV by bombarding Ag2S targets, enriched to 1.93% in S36. The half-life was measured to be 169.6 ± 0.7 min. The main β branch (83 ± 2)% with end-point energy 1005 ± 20 keV proceeds to a previously unidentified level of Cl38 at 1942 keV. A 1941.7 ± 0.2-keV γ ray has been observed in coincidence with this branch. The ΔT=1 β transition is allowed (logft=4.98±0.03) giving Jπ=1+ for Cl38 (1942 keV). The γ decay of the 1942-keV level proceeds 100% to the Cl38 ground state, and an upper limit of 0.4% can be set for any other possible decay mode. No γ rays in coincidence with the 1942-keV γ ray were observed. The β- and γ-ray measurements determine the Q value for the S38(β)Cl38 reaction as 2947 ± 20 keV. In addition to the main branch a (2.8 ± 0.3)% branch proceeds to the 1746.2 ± 0.4-keV level, which decays predominantly to the Cl38 ground state. The logft of 6.76±0.05 restricts the 1746-keV level to have Jπ=0,1, or 1+; the Cl37(d,p) reaction establishes the parity as odd. No other γ rays from Cl38 were observed, which leads to a value of (14.2 ± 2)% for the ground-state β branch and to a unique first-forbidden matrix element, G12, of 1.53 ± 0.22 F2, in excellent agreement with theoretical calculations. The Coulomb energy difference between Cl38 and S38 is determined as 6051 ± 32 keV. The isobaric-multiplet mass equation is used to predict the masses of the lowest Jπ=0+, T=3 states in K38, Ca38, Sc38, and Ti38. The predicted mass excess for Ti38 is + 10.55 ± 0.78 MeV.

  • Received 8 September 1970

DOI:https://doi.org/10.1103/PhysRevC.3.180

©1971 American Physical Society

Authors & Affiliations

G. A. P. Engelbertink and J. W. Olness

  • Brookhaven National Laboratory, Upton, New York 11973

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Vol. 3, Iss. 1 — January 1971

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