First experimental results on creation and decay of eta-mesic nuclei
G.A. Sokol, T.A. Aibergenov, A.V. Koltsov, A.V. Kravtsov, Yu.I. Krutov, A.I. L'vov, L.N. Pavlyuchenko, V.P. Pavlyuchenko, S.S. Sidorin
Abstract
First experimental results on photoproduction of eta-mesic nuclei are analyzed. In an experiment performed at the 1 GeV electron synchrotron of the Lebedev Physical Institute, correlated (pi+,n) pairs arising from the reaction \gamma + C12 -> N + (A-1)_eta -> N + (pi+,n) + (A-2) and flying transversely to the photon beam have been observed. When the photon energy exceeds the eta-meson production threshold, a distribution of the (pi+,n) pairs over their total energy is found to have a peak in the subthreshold region of the internal-conversion process eta p -> pi+ n which signals about formation of eta-mesic nuclei.