Spectroscopy near the proton drip-line in the A = 130 mass region C.M. PETRACHE,* G. LO BIANCO,* A. SALTARELLI,* M. NESPOLO, t D. BAZZACCO, t T. KROLL, t S. LUNARDI, t E. MAGLIONE, t R. MENEGAZZO, t B. QUINTANA, f F. SPOLAORE, t M. AXIOTIS, $ G. DE ANGELIS, ~ N. MARGINEAN, $ T. MARTINEZ,$ D.R. NAPOLI, t N. BLASI w * Dipax~imento di MaCematica e Fisica, University os Camerino, Camerino, ItaJy t Dipar~imento di Fisica and INFN, Sezione di Padova, Padova, Ita]y t INFN, Laboratori Nazionah" di Legnaro, Legnaxo, Italy INFN, Sezione di Milano, Milano, Italy The near' proton drip-line nucleus 12epr was studied via in-beam v-ray spectroscopy using the 4~ reactionat 190 MeV. We observedfor the first time excitedstates above the known isomer in thisnucleus,up to spin 31h. The observed band isassignedto a 7rh11/2@ vhH/2 configuration. The experimental informationsuggest a spin 8+ for the lowest observed state.With such a spin assignment the excitationenergy of the excited statesin 12epr and ~2SPrget smallerthan in the heavierPr isotopes, suggestinga sudden change in deformation closeto the proton drip line. 1 Introduction Very recently,the proton radioactivityfrom IS~Eu and 141Ho has been identi- fied [1] and the decay rate deviates significantly from calculationsassuming spher- ical configurations,thus indicatingthe onset of large deformations in the drip line nuclei below Z=69. Predictions by relativistic mean fieldcalculationssupport these experimental resultsand suggest the position of the proton drip line [2].The life- times of the proton-decaying isomers are extremely sensitiveto the orbital angular momentum Iof the emitted proton and can vary over several orders of magnitude when changing the angular momentum of the occupied orbital. The position of the orbitalsat the Fermi surface depends strongly on the/32 deformation [3].It is therefore very important to determine the quadrupole deformation of the nuclei at and beyond the proton drip-line,in order to locate the orbitalsclose to the Fermi surface and to estimate the lifetimeof the isomers, which is essentialwhen looking for new proton emitters.The deformation of the nucleiat the proton drip linein the A -- 130 mass region can be experimentally tested eitherby comparing the lifetimes of proton emitters with theoreticalpredictions or by investigatingthe level struc- ture of particlebound nuclei closeto the drip line.For Z = 59 the proton drip line is predicted to correspond to the isotopes 124Pr [2], while the lighter,12Spr nucleus lieson the line defined by the known proton emitters in a N-Z map [4].The light- est Pr nucleus for which spectroscopic information has been published is 127Pr [5], while the lightest odd-odd Pr nucleus with known excited states is 12SPr [6].In order to investigatethe variationof the deformation when approaching the proton drip-line,we have studied the 12Spr nucleus in an experiment performed with the Czechoslovak Journal of Physics, Vol. 51 (2001), Suppl. A A261