Gamma ray spectroscopy in 64Zn - levels below 3.1 MeV in excitation

States in 64Zn were populated using the 61Ni(α,nγ)64Zn reaction at a beam energy of 7.8 MeV. Excitation energies, gamma ray branching ratios, angular distribution, linear polarisations and centroid shifts were measured for levels in 64Zn below 3.1 MeV in excitation. Electromagnetic multipole mixing ratios were determined for many of the gamma ray transitions. New spin and parity assignments of Jsup(π) = 3+ and 2+ have been made for the levels at 2979 keV and 3005 keV, whilst the spins and parities of the 2737, 2794 and 3078 keV levels are confirmed at 4+, 2+ and 4+ respectively. The spin and parity of the 3093 keV level has been restricted to either 3+ or 2+. Mean lifetimes of the 2306, 2609, 2794, 2997, 3005, 3078 and 3093 keV levels were deduced, using the Doppler-shift attenuation method, to be 420 +- 120, 520 +- 150, 70 +- 20, 115 +- 30, 115 +- 30, 610 +- 160 and 125 +- 30 fs respectively. Limits on the mean lifetimes of several other levels have been made. The results are discussed in terms of recent shell-model calculations using a closed 56Ni core. (author)