Recent advances and future trends in neutron resonance spectroscopy

Neutron resonance spectroscopy contributes primarily to two areas of nuclear physics: In medium weight and heavy nuclei with a high level density it tests their statistical properties; in nuclei with a sufficiently low level density, i.e. light nuclei (A <= 50) and nuclei around 208Pb, it investigates nuclear structure at several MeV excitation energy. In the first field, recent years have seen growing knowledge and understanding of nuclear level densities and their spin and parity dependence. Several questions basic to the statistical properties of nuclei, although extensively studied in the past, are still open: the statistical distribution of partial widths; possible narrow energy variations of the average partial widths; and correlations between partial widths for different reaction channels. The major progress has occured and will continue to take place in the field of light nuclei: Improved resolution of neutron time-of-flight spectrometers yields detailed resonance data over an extended energy range, and model calculations become possible which will allow detailed comparison to experimental data. The main subjects of interest are the distributions of neutron- as well as radiative strengths and their interpretation in terms of nuclear structure. (author)