Nuclear Structure and Decay Data for A=44 Isobars

Abstract

Experimental nuclear spectroscopic data are evaluated for 12 known nuclides of mass number A=44 (Si, P, S, Cl, Ar, K, Ca, Sc, Ti, V, Cr, Mn). Detailed evaluated information are presented for each reaction and decay. Recommended values combining all available data are provided for all spectroscopic properties of each level, γ-ray, and decay radiation. No excited states have yet been identified in ⁴⁴Si, ⁴⁴P, ⁴⁴Cr, and ⁴⁴Mn. Information for excited states in ⁴⁴Cl and ⁴⁴V are limited. Nuclides of ⁴⁴S, ⁴⁴Ar and ⁴⁴K have been studied via only a few reactions and decays, while ⁴⁴Ca, ⁴⁴Sc and ⁴⁴Ti are the most investigated nuclides through various reactions and decays. Evaluators note that the half-life of the g.s. of ⁴⁴S has been measured independently, with fairly good statistics, in three references, most precise being 100 ms 1 by 2004Gr20, but this value is in disagreement with the values of 125.5 ms 25 and 119 ms 6 by 2022Tr03, and 123 ms 10 by 1995So03. We adopted the unweighted average of this discrepant dataset. Another outstanding issue is that of the β⁺-delayed proton decay of ⁴⁴Cr g.s. to ⁴⁴V, where the T=2, 0⁺ IAS state in ⁴⁴V is expected to be strongly populated by a superallowed β transition, but has not been definitely identified as discussed in detail by 2020Fu05. A detailed study of ⁴⁴Cr decay is required to unravel the status of the T=2, 0⁺ IAS state in ⁴⁴V. This work supersedes earlier ENSDF evaluations of A=44 by 2011Ch39 and 1999Ca45.