Spectroscopy of the proton emitter I-109

Excited states in the proton-unbound nucleus I-109 were populated using the Fe-54(Ni-58.p2n) reaction at a beam energy of 220 MeV. Gamma rays in I-109 were identified using the rceoil-decay tagging technique. The analysis of proton-correlated gamma gamma coincidence data produced the yrast decay seq uence in I-109, which can be tentatively assigned as built on the h(11/2) p roton state based on systematic trends in the neighboring isotopes. This se quence is completely different from that reported previously. A comparison of the him band in I-109 with those in heavier iodines shows that I-109 con tinues the trend of decreasing quadrupole deformation with decreasing neutr on number. [S0556-2813(99)50804-2].