Investigation of the = 0 selection rule in Gamow-Teller transitions; The -decay of Hg

Berry, T. A.*; Podolyk, Zs.*; Carroll, R. J.*; Lic, R.*; Grawe, H.*; Timofeyuk, N. K.*; Alexander, T.*; Andreyev, A. N.; Ansari, S.*; Borge, M. J. G.*; Creswell, J.*; Fahlander, C.*; Fraile, L. M.*; Fynbo, H. O. U.*; Gelletly, W.*; Gerst, R.-B.*; Grska, M.*; Gredley, A.*; Greenlees, P.*; Harkness-Brennan, L. J.*; Huyse, M.*; Judge, S. M.*; Judson, D. S.*; Konki, J.*; Kurcewicz, J.*; Kuti, I.*; Lalkovski, S.*; Lazarus, I.*; Lund, M.*; Madurga, M.*; Mrginean, N.*; Mrginean, R.*; Marroquin, I.*; Mihai, C.*; Mihai, R. E.*; Ncher, E.*; Nae, S.*; Negret, A.*; Nita, C.*; Page, R. D.*; Pascu, S.*; Patel, Z.*; Perea, A.*; Pucknell, V.*; Rahkila, P.*; Rapisarda, E.*; Regan, P. H.*; Rotaru, F.*; Shand, C. M.*; Simpson, E. C.*; Sotty, Ch.*; Stegemann, S.*; Stora, T.*; Tengblad, O.*; Turturica, A.*; Van Duppen, P.*; Vedia, V.*; Wadsworth, R.*; Walker, P. M.*; Warr, N.*; Weaving, F.*; De Witte, H.*

Gamow-Teller decay is forbidden if the number of nodes in the radial wave functions of the initial and final states is different. This = 0 requirement plays a major role in the decay of heavy neutron-rich nuclei, affecting the nucleosynthesis through the increased half-lives of nuclei on the astrophysical -process pathway below both = 50 (for 82) and = 82 (for 126). The level of forbiddenness of the = 1 10 transition has been investigated from the decay of the ground state of Hg into the single-proton-hole nucleus Tl in an experiment at the ISOLDE Decay Station. From statistical observational limits on possible -ray transitions depopulating the 0 state in Tl, an upper limit of 3.910 % was obtained for the probability of this decay, corresponding to log 8.8 within a 95% confidence limit. This is the most stringent test of the = 0 selection rule to date.