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Abstract

An excited metastable nuclear state of ¹⁹²Os in a hydrogen-like charge state has been studied for the first time. It was populated in projectile fragmentation of a of ¹⁹⁷Au beam on a of ⁹Be target with the UNILAC-SIS accelerators at GSI. Fragmentation products in the region of interest were passed through the fragment separator and injected into the experimental storage ring (ESR). Cooling of the injected beam particles enabled Schottky mass spectrometry to be performed. Analysis shows the lifetime of the state to be considerably longer than that of the neutral ion [τneut=8.5(14)s]; this change is attributed to hindrance of internal conversion in hydrogen-like of ¹⁹²Os. Calculations have been performed to estimate the lifetime, and the result has been compared with that measured experimentally. There is good agreement between the expected [τH−like=13.0(24)s] and measured lifetimes (τrest=15.1^+1.5_{−1.3 s}) from the internal decay of of ^192mOs. This provides a test for the reliability of the values obtained from internal conversion coefficient calculations in highly ionized systems and is the first measurement of its kind to be performed using the ESR setup.