Excited0+states in62Zn populated via the64Zn(p,t)62Zn reaction

K. G. Leach, P. E. Garrett, C. E. Svensson, I. S. Towner, G. C. Ball, V. Bildstein, B. A. Brown, A. Diaz Varela, R. Dunlop, T. Faestermann, R. Hertenberger, D. J. Jamieson (+3 others)
2013 Physical Review C  
A search for excited 0 + states in 62 Zn was conducted via the 64 Zn(p, t) 62 Zn reaction. Four such states in 62 Zn were observed up to an excitation energy of 5.4 MeV. The measured angular distribution for the previously assigned 0 + 2 state at 2342 keV is consistent with a 2 + assignment, and thus the first excited 0 + state is now assigned at 3043 keV. Due to the energy scaling in the currently adopted formalism for isospin-mixing corrections in superallowed Fermi β decay, δ C1 for 62 Ga is
more » ... , δ C1 for 62 Ga is reduced by nearly a factor of two. This result shifts the theoretical value closer to previous experimental determinations of the same quantity through 62 Ga superallowed β-decay branching-ratio measurements. Superallowed 0 + → 0 + nuclear β-decay data currently provide the most precise determination of the vector coupling constant for weak interactions, G V [1,2]. The extraction of G V from these data is vital to determine the up-down element of the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing matrix, V ud [2] . In order to obtain V ud from the high-precision superallowed data, corrections to the nucleus-dependent β-decay ft values for these nuclei must be made [2] : where δ R is a transition-dependent radiative correction, R is a transition-independent radiative correction, and δ C is a nucleus-dependent isospin-symmetry-breaking (ISB) correction. Although small (∼1%), these corrections are crucial due to the very precise experimental ft values [1], obtained through measurements of the β-decay half-lives, branching ratios, and Q-values for superallowed decays. The current uncertainty for G V is, in fact, dominated by the precision of these theoretical corrections; most notably the transition-independent radiative correction R [3] and the ISB corrections [2] . Although there has been a great deal of recent theoretical work regarding the ISB calculations [4] [5] [6] [7] [8] [9] [10] [11] , precision Standard Model tests generally adopt the formalism and refinements developed by Towner and Hardy [1, 12] . Their current method uses a separation of δ C into a sum of two terms, one which results from different configuration mixing between the parent and daughter states in the superallowed * Present address: TRIUMF,
doi:10.1103/physrevc.88.031306 fatcat:kcidrzlufnfdjbusijivbtemuu