Abstract
We have found a long-lived metastable state of stopped in liquid helium by measuring the time spectra of two different delayed products: (i) protons emitted after absorption by nuclei and (ii) 70-MeV electrons originating from free →¯ decay. The lifetime and fraction of delayed absorption obtained by using the emitted protons are 7.26±0.12 nsec and 1.66±0.05%, respectively. The free-decay fraction of a pion in liquid helium was obtained to be 0.64±0.03% from this result, which is consistent with the observed free- decay fraction. These results imply that 2.30±0.07% of stopped are trapped in the metastable state which have an overall lifetime of 10.1±0.2 nsec. The same experimental and analysis were performed for stopped in liquid neon, where no evidence for trapping was found.
- Received 6 November 1991
DOI:https://doi.org/10.1103/PhysRevA.45.6202
©1992 American Physical Society