Proton states in193Ir and195Ir populated via the (α) reaction

The nuclear structures of¹⁹³Ir and¹⁹⁵Ir have been studied using the¹⁹⁴Pt(t, α) and¹⁹⁶Pt(t, α) reactions. Levels up to ～2MeV in excitation energy were studied with a resolution of ～13keV (FWHM) and spectroscopic strengths were extracted. The low-lying states in¹⁹³Ir have been interpreted in terms of both the Nilsson and the rotation-vibration models including Coriolis, particle-vibration and rotation-vibrational couplings. The previously assigned 3/2⁺ 402], 11/2^? 505], 1/2⁺400] and 1/2⁺411] bands were populated and candidates for the 5/2⁺ 402] and 7/2⁺ 404] bandheads were observed. TheK ₀ +2 gamma vibration based on the ground state was populated because it is mixed with the 7/2⁺ 404] state. Surprisingly, there was no significant difference between the stripping and pick-up strengths for the low-lying states in¹⁹³Ir, suggesting that the equilibrium nuclear shape of¹⁹³Ir has large overlaps with the shapes of both¹⁹²Os and¹⁹⁴Pt. The nuclear level structure of¹⁹⁵Ir appears to be similar to those of the lighter iridium isotopes.