Search for a 2-quasiparticle high- isomer in Rf
Robinson, A. P.*; Khoo, T. L.*; Seweryniak, D.*; Ahmad, I.*; Asai, Masato ; Back, B. B.*; Carpenter, M. P.*; Chowdhury, P.*; Davids, C. N.*; Greene, J.*; Greenlees, P. T.*; Hauschild, K.*; Heinz, A.*; Herzberg, R.-D.*; Janssens, R. V. F.*; Jenkins, D. G.*; Jones, G. D.*; Ketelhut, S.*; Kondev, F. G.*; Lauritsen, T.*; Lister, C. J.*; Lopez-Martens, A.*; Marley, P.*; McCutchan, E.*; Papadakis, P.*; Peterson, D.*; Qian, J.*; Rostron, D.*; Shirwadkar, U.*; Stefanescu, I.*; Tandel, S. K.*; Wang, X.*; Zhu, S.*
We have identified an isomer with a half-life of 17 s in Rf through a calorimetric conversion electron measurement tagged with implanted Rf nuclei using the fragment mass analyzer at Argonne National Laboratory. The low population yield for this isomer suggests that this isomer should not be a 2-quasiparticle high- isomer which is typically observed in the N = 152 isotones, but should be a 4-quasiparticle one. Possible reasons of the non-observation of a 2-quasiparticle isomer are this isomer decays by fission with a half-life similar to that of the ground state of Rf. Another possibility, that there is no 2-quasiparticle isomer at all, would imply an abrupt termination of axially symmetric deformed shape at Z=104.