New positive-parity states and the shell-model description of 111Sn

The excited states in 111Sn have been studied by means of three different reactions using inbeam spectroscopic methods. Energies and intensities of γ-rays have been determined via the (α,n), (3He, 3n) and (6Li, 4n) reactions. Coincidences, angular and time distributions have been measured in the (α, n) and (3He, 3n) reactions. Conversion-electron spectra have been recorded in the (α, n) reaction. As a result, 9 levels of even parity have been identified with spin values between 9/2 and (17/2) and excitation energies up to 2.5 MeV, and three additional odd-parity states have been established up to Esub(x)<3307 keV. Besides the 11-/2 isomer, three further levels with ns lifetimes were found. The experimental data are compared with shell-model predictions. The hamiltonian parameters have been determined in a fit to 22 known levels of sup(111,112,113)Sn. In the case of even-parity states a remarkable agreement between experiment and theory can be stated. For the description of odd-parity states a particle-core-coupling model is successfully applied. (orig.)