In-beam spectroscopy study of the proton emitter Lu-151

Gamma rays decaying from the excited states of the proton-unbound Lu-151 we re observed for the first time in an experiment using the Ru-96(Ni-58, p2n) Lu-151 reaction. These gamma rays were identified by correlating prompt gam ma radiations at the target position with Lu-151 proton radioactivities at the focal plane of a recoil mass separator. Systematic data on N = 80 isoto nes suggest a possible isomeric level at high spin in Lu-151. Our measureme nt was unable to observe such an isomer, but provided an upper limit on its half-life. The observed gamma rays in Lu-151 can be interpreted in terms o f two possible level structures. [S0556-2813(98)50812-6].