Cassidy, DavidHunt, A. W.Asoka-Kumar, P.Bhat, B. V.Cowan, T. E.Howell, R. H.Lynn, K. G.Mills, A. P.Palathingal, J. C.Golovchenko, Jene2016-11-172001Cassidy, D. B., A. W. Hunt, P. Asoka-Kumar, B. V. Bhat, T. E. Cowan, R. H. Howell, K. G. Lynn, A. P. Mills, J. C. Palathingal, and J. A. Golovchenko. 2001. Resonant Versus Nonresonant Nuclear Excitation of 115 In by Positron Annihilation. Physical Review C 64, no. 5: 1-5. doi:10.1103/physrevc.64.054603.0556-2813http://nrs.harvard.edu/urn-3:HUL.InstRepos:29405822We have measured the resonant cross section σn for nuclear excitation of 115In via the radiationless annihilation of a positron with a K-shell electron using a monoenergetic positron beam and a thin In target. We find an upper limit on the resonant cross section σn<4.3×10−26cm2 at a 99% confidence level, compared to the cross section σβ=1.7×10−25cm2 determined by two previous measurements of nuclear excitation of 115In using the broad spectrum of positrons from the beta decay of 64Cu. Together these results imply the existence of a hitherto unidentified nonresonant channel for nuclear excitation via energetic positrons.en-USJournal Article2016-11-1710.1103/PhysRevC.64.054603