The x-ray cascade from antiprotonic atoms was studied for 208 Pb and 209 Bi. Widths and shifts of the levels due to the strong interaction were determined. Using modern antiproton-nucleus optical potentials, the neutron densities in the nuclear periphery were deduced. Assuming two-parameter Fermi distributions (2pF) describing the proton and neutron densities, the neutron rms radii were deduced for both nuclei. The difference of neutron and proton rms radii r np equal to 0.16 ± (0.02) stat ± (0.04) syst fm for 208 Pb and 0.14 ± (0.04) stat ± (0.04) syst fm for 209 Bi were determined, and the assigned systematic errors are discussed. The r np values and the deduced shapes of the neutron distributions are compared with mean field model calculations.

The location of several single-neutron states in 133 Sn has been identified. The p 3͞2 , h 9͞2 , and f 5͞2 states were found at 853.7, 1560.9, and 2004.6 keV, respectively, by measuring g rays in coincidence with delayed neutrons following the decay of 134 In. Crucial for obtaining the new data were the improved yields at the mass-separator facility ISOLDE-PSB at CERN. A semiempirically adjusted Woods-Saxon calculation, based on parameters from the Pb region and normalized on the mass data at 132 Sn, reproduces the new single particle energies with good precision. [S0031-9007(96)00824-1]

Very neutron-deficient isotopes of rhodium, palladium, silver, cadmium and indium in the N= 50 region were studied at the GSI on-line mass separator following bombardment of 58, 60, 62Ni and 63, 65Cu targets with 4.0 MeV/u ions of 4~The known 'properties of the t-delayed proton precursor 95mpd were confirmed, but a search for direct proton decay of 95mAg was not successful. Beta-delayed proton activities observed at mass-numbers 94, 96, 97 and 100 were assigned to the precursors 94Rh(66_+14 s), 96Ag(5.1 + 0.4 s), 97 +4 lOOin" . _ Cd(3 z s) and In addition. 94pd(9.0+0.5 s) was identified from fl-y-X studies. Individual decay schemes of 95~, 96pd and 96, 9SAg are reported.

Thirteen targets with mass numbers from 58 to 238 were irradiated with the antiproton beam from the Low Energy Antiproton Ring facility at CERN leading to the formation of antiprotonic atoms of these heavy elements. The antiproton capture at the end of atomic cascade results in the production of more or less excited residual nuclei. The targets were selected with the criterion that both reaction products with one nucleon less than the proton and neutron number of the target are radioactive. The yield of these radioactive products after stopped-antiproton annihilation was determined using gamma-ray spectroscopy techniques. This yield is related to the proton and neutron density in the target nucleus at radial distance corresponding to the antiproton annihilation site. The experimental data clearly indicate the existence of a neutron rich nuclear periphery, a "neutron halo", strongly correlated with the target neutron separation energy Bn, and observed for targets with Bn < 10 MeV. For two target nuclei, 106 Cd and 144 Sm, with larger neutron binding energies a proton rich nuclear periphery was observed. Most of the experimental data are in reasonable agreement with calculations based on current antiproton-nucleus and pion-nucleus interaction potentials and on nuclear densities deduced with the help of the Hartree-Fock-Bogoliubov approach. This approach was, however, unable to account for the 106 Cd and 144 Sm results.

Using on-line mass separation of evaporation residues from the reaction S8Ni +92Mo--,15~ a proton line of 1,055_+6keV energy and 0.42_+0.10s half-life was observed at mass number 147. The origin of this activity is very likely the direct proton decay of 147Tm. Beta-delayed protons registered at the same mass position show a pronounced peak structure in their energy distribution. A lower limit of their half-life was set to 1 s.