First observation of $\beta$-delayed $\gamma$-proton decay in the $T_z$ = -2, $^{56}$Zn nucleus

S. E. A. Orrigo , B. Rubio , Y. Fujita , Bertram Blank (1) , W. Gelletly , J. Agramunt , A. Algora , P. Ascher (1) , B. Bilgier , L. Caceres (2) , R. B. Cakirli , H. Fujita , E. Ganioğlu , M. Gerbaux (1) , J. Giovinazzo (1) , S. Grévy (1) , O. Kamalou (2) , H. C. Kozer , L. Kucuk , T. Kurtukian Nieto (1) , F. Molina , L. Popescu , A. M. Rogers , G. Susoy , C. Stodel (2) , T. Suzuki , A. Tamii , J.C. Thomas (2)

1 NEX - Noyaux exotiques
2 GANIL - Grand Accélérateur National d'Ions Lourds

We report on the first experimental observation of a very exotic decay mode at the proton drip-line, the $\beta$-delayed $\gamma$-proton decay, clearly seen in the $\beta$ decay of the $T_z$ = -2, $^{56}$Zn nucleus. The $^{56}$Zn half-life and decay scheme have been determined. The decay proceeds by $\beta$-delayed proton emission and $\beta$-delayed $\gamma$ de-excitation. The exotic $\beta$-delayed $\gamma$-proton emission was also detected in three cases. It affects the usual determination of the Gamow-Teller (GT) strength. Absolute Fermi and GT strengths have been deduced. Evidence for fragmentation of the Fermi strength due to isospin mixing is found.

Domaines: Physique Nucléaire Expérimentale [nucl-ex]; Physique Nucléaire Théorique [nucl-th]

S. E. A. Orrigo, B. Rubio, Y. Fujita, Bertram Blank, W. Gelletly, et al.. First observation of $\beta$-delayed $\gamma$-proton decay in the $T_z$ = -2, $^{56}$Zn nucleus. Physical Review Letters, 2014, 112, pp.939876. ⟨10.1103/PhysRevLett.112.222501⟩. ⟨in2p3-00939876⟩