The differences between neutron and proton density distributions at large nuclear radii in stable nuclei were determined. Two experimental methods were applied: nuclear spectroscopy analysis of the antiproton annihilation residues one mass unit lighter than the target mass and the measurements of strong-interaction effects on antiprotonic x rays. Assuming the validity of two-parameter Fermi neutron and proton distributions at these large radii, the conclusions are that the two experiments are consistent with each other and that for neutron rich nuclei it is mostly the neutron diffuseness which increases and not the half-density radius. The obtained neutron and proton rms radii differences are in agreement with previous results.

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The nuclear periphery was studied by using antiprotons. Two experimental methods were applied: analysis of the antiproton annihilation residues one mass unit lighter than the target mass by nuclear spectroscopy and the measurement of strong interaction effects on antiprotonic level widths and shifts. 26 isotopes from a wide range of mass numbers (40<A<238) were investigated. The gathered antiprotonic-atom data were compared with the results obtained using hadron scattering methods and with some expectations from theoretical approaches.

Fluctuation properties have been analyzed for a large collection of low-lying nuclear energy levels, with emphasis on the nearest-neighbor spacing distributions. The levels are combined in several ways to search for effects due to mass, spin, and shape. A strong mass dependence appears to be present, and there are suggestions of effects due to spin and deformation.

The first measurement of the elementary process $\mu^- p \rightarrow \nu_{\mu} n \gamma$ is reported. A photon pair spectrometer was used to measure the partial branching ratio ($2.10 \pm 0.22) \times 10^{-8}$ for photons of k > 60 MeV. The value of the weak pseudoscalar coupling constant determined from the partial branching ratio is $g_p(q^{2}=-0.88m_{\mu}^2) = (9.8 \pm 0.7 \pm 0.3) \cdot g_a(0)$, where the first error is the quadrature sum of statistical and systematic uncertainties and the second error is due to the uncertainty in $\lambda_{op}$, the decay rate of the ortho to para $p \mu p$ molecule. This value of g_p is $\sim$1.5 times the prediction of PCAC and pion-pole dominance.Comment: 13 pages, RevTeX type, 3 figures (encapsulated postscript), submitted to Phys. Rev. Let

We present evidence for a new supersymmetric quartet in the A ∼ 190 region of the nuclear mass table. New experimental information on transfer and neutron capture reactions to the odd-odd nucleus 194 Ir strongly suggests the existence of a new supersymmetric quartet, consisting of the 192,193 Os and 193,194 Ir nuclei. We make explicit predictions for the odd-neutron nucleus 193 Os and suggest that its spectroscopic properties be measured in dedicated experiments.

The level density parameters for backshifted Fermi gas (both without and with energy-dependent level density parameter) and constant-temperature models have been determined for 310 nuclei between 18 F and 251 Cf by fitting of the complete level schemes at low excitation energies and s-wave neutron resonance spacings at the neutron binding energies. Simple formulas are proposed for the description of the two parameters of each of these models, which involve only quantities available from the mass tables. These formulas may constitute a reliable tool for extrapolating to nuclei far from stability, where nuclear level densities cannot be measured.