gamma-band staggering and E(5)-type structure: Zn-64

The staggering factor S{sub 4} in the quasi-{gamma} band was used for the first time as a signature of the E(5) symmetry. This observable, together with the R{sub 4/2} ratio is used to find E(5) type nuclei in the Z=28-50 and Z=50-82 shells. An E(5) candidate is found to be {sup 64}Zn. Low-spin states in {sup 64}Zn populated in the {epsilon}/{beta}{sup +} decay of {sup 64}Ga, produced in the {sup 54}Fe({sup 12}C,pn){sup 64}Ga, were studied through off-beam {gamma}-ray spectroscopy. The decay scheme of {sup 64}Zn is found to be reasonably close to the predictions of the E(5) critical point symmetry. The structure of the excited 0{sup +} states in {sup 64}Zn and their behavior in the Zn isotopic chain is discussed.