Identification of high-spin states in the stable nucleus ${}^{195}$Pt

Excited states of the stable nucleus ${}^{195}$Pt have been studied using an in-beam $\gamma$-ray spectroscopic technique following the incomplete fusion of ${}^7$Li on an ${}^{192}$Os target at 44 MeV. A level scheme built on the $I^{\pi }=13/2^{+}$ isomer has been established up to $I^{\pi }=33/2^{-}$ at an excitation energy of about 2.6 MeV. Spin and parity values of these states have been assigned from an analysis of anisotropy ratios of $\gamma$ rays and by analogy with the neighboring nuclei. A comparison of the observed structures with the yrast states in the neighboring even-even ${}^{196}$Pt core indicates that the identified levels may be regarded as arising from the weak coupling of a $\nu \mathrm{i}$${}_{13/2}$ neutron hole to the core states.

Figure 1

The $\gamma$-ray coincidence spectra by setting a gate on (a) 341.0-keV $17/2^{+}\to 13/2^{+}$ transition in ${}^{193}$Pt, (b) 328.5-keV $2^{+}\to 0^{+}$ transition in ${}^{194}$Pt, (c) 368.8-keV transition, and (d) 355.6-keV $2^{+}\to 0^{+}$ transition in ${}^{196}$Pt.

Figure 2

Level scheme of ${}^{195}$Pt deduced from this work. The widths of the arrows indicate the relative transition intensities.

Figure 3

The $\gamma$-ray coincidence spectra gated on (a) the 578.1-keV transition and (b) the 204.5-keV transition. Contaminant lines indicated by solid circles arise from ${}^{192}$Os, which are in coincidence with 205.8-keV $2^{+}\to 0^{+}$ transition [19].

Figure 4

Projected spectra at a mean angle of (a) 35${}^{\circ }$ and (b) 90${}^{\circ }$ by setting a gate on the 368.8-keV transition at all angles.

Figure 5

Energy systematics of excited states in ${}^{191-196}$Pt. The excitation energies of the 13/2${}^{+}$ states in odd-$A$ ${}^{191,193,195}$Pt have all been normalized to the yrast levels of 0${}^{+}$ in even-even ${}^{192,194,196}$Pt for comparison. Solid (empty) symbols denote the excited states of odd-$A$ (even-even) Pt isotopes. Data are taken from Ref. [19] and the present work.