In-beam γ-ray spectroscopy of Pt isotopes located at the proton drip line

In-beam g rays have been observed in the neutron-deficient isotopes 170,171,172Pt using the recoil-decay tagging technique. The yrast transition sequence proposed for 172Pt indicates that the 01 bandhead of the deformed intruder band is situated about 900 keV above the weakly deformed ground state, i.e., its excitation energy has risen by about 300 keV compared to 174Pt. The measured energy of the 21 !01 transition in 170Pt supports an even larger increase in the excitation energy of the intruder configuration with the departure from the middle of the 82–126 major neutron shell. Furthermore, a band with transition energies almost identical to those found in 172Pt has been assigned to 171Pt and was interpreted as corresponding to a rotationally aligned i13/2 neutron orbital coupled to the core excitations