Spectroscopy of superheavy hydrogen isotopes in stopped-pion absorption by nuclei

The structure of levels of superheavy hydrogen isotopes H4-6 is analyzed on the basis of a record statistics of experimental data on the absorption of negatively charged pions by light nuclei. Qualitatively new experimental data are obtained for the spectroscopy of the superheavy hydrogen isotopes H-5 and H-6. Peaks due to four resonance states of H-5 are observed in the missing-mass spectra for the reaction channels Be-9(pi(-), pt)X and Be-9(pi(-), dd)X. A structure that is associated with four resonance states of H-6 is observed in the missing-mass spectra for the reaction channels Be-9(pi(-), pd)X and B-11(pi(-), p(4)He)X. On the basis of the results presented for ground-state parameters, it can be concluded that the binding energy of superheavy hydrogen isotopes decreases as the number of neutrons increases. Excited levels of the isotopes H-5 and H-6 are observed for the first time. On the energy scale, all of these states lie above the threshold for decay to free nucleons. (c) 2005 Pleiades Publishing, Inc.