This volume contains the proceedings of the "Conference on the (p,n) Reaction and the Nucleon-Nucleon Force" held in Telluride, Colorado, March 29-31, 1979. The idea to hold this conference grew out of a program at the Indiana University Cyclotron Facility to study the (p,n) reaction in the 50-200 MeV energy range. The first new Indiana data, in contrast to low energy data, showed features suggestive of a dominant one pion exchange interaction. It seemed desir able to review what was known about the fre·e and the effective nucleon-nucleon force and the connection between the low and high energy (p,n) data. Thus the conference was born. The following people served as the organizing committee: S. M. Austin, Michigan State University W. Bertozzi, Massachusetts Institute of Technology S. D. Bloom, Lawrence Livermore Laboratory C. C. Foster, Indiana University C. D. Goodman, Oak Ridge National Laboratory (Conference Chairman) D. A. Lind, University of Colorado J. Rapaport, Ohio University G. R. Satch1er, Oak Ridge National Laboratory G. E. Walker, Indiana University R. L. Walter, Duke University and TUNL The sponsoring organizations were: Indiana University, Bloomington, Indiana University of Colorado, Boulder, Colorado Oak Ridge National Laboratory, Oak Ridge, Tennessee Triangle Universities Nuclear Laboratory, Durham, North Carolina Of course, the major credit for the success of the con ference must go to the speakers who diligently prepared their talks that are reproduced in this volume.

This book provides a comprehensive overview of some key developments in the understanding of the nucleon-nucleon interaction and nuclear many-body theory. The main problems at the level of meson exchange physics have been solved, and we have an effective field theory using a phenomenological interaction pioneered by Achim Schwenk and Scott Bogner, which is nearly universally accepted as a unique low-momentum interaction that includes all experimental data to date.This understanding is based on a multi-step development in which different scientific insights and a wide range of physical and mathematical methodologies fed into each other. It is best appreciated by looking at the different 'steps along the way', starting with the pioneering work of Brueckner and his collaborators that was just as necessary and important as the insightful masterly improvements to Brueckner's theory by Hans Bethe and his students. Moving on from there, the off-shell effects that bedeviled Bethe's work — which had resulted in the 1963 Reference Spectrum Method — were treated relatively accurately by introducing an energy gap between initial bound states and an intermediate state. With their influential 1967 paper, Brown and Kuo prepared the effective field theory. Later, the introduction of 'Brown-Rho scaling' deepened understanding of saturation in the many-body system and fed directly into recent work on carbon-14 dating.

We studied simultaneously the 4He(e, e'p), 4He(e, e'pp), and 4He(e, e'pn) reactions at Q2=2 [GeV/c]2 and xB>1, for a (e, e'p) missing-momentum range of 400 to 830 MeV/c. The knocked-out proton was detected in coincidence with a proton or neutron recoiling almost back to back to the missing momentum, leaving the residual A=2 system at low excitation energy. These data were used to identify two-nucleon short-range correlated pairs and to deduce their isospin structure as a function of missing momentum in a region where the nucleon-nucleon force is expected to change from predominantly tensor to repulsive. Neutron-proton pairs dominate the high-momentum tail of the nucleon momentum distributions, but their abundance is reduced as the nucleon momentum increases beyond ~500 MeV/c. The extracted fraction of proton-proton pairs is small and almost independent of the missing momentum in the range we studied. Our data are compared with ab-initio calculations of two-nucleon momentum distributions in 4He.

This volume contains the proceedings of the "International Conference on Spin Excitations in Nuclei" held in Telluride, Colo rado, March 25-27, 1982. The motivation for the conference was, in a large part due to the recent development of new variable energy accelerators which produce high quality beams of electrons, protons, and pions that are providing the first precise information on spin excitations in nuclei over a large range of spin and mass. In the past such data had been restricted primarily to light nuclei and were generally resolution limited. Perhaps, the most exciting new result has been the clear observation of the elusive spin-dipole strength (Gamow Teller and Ml) in medium and heavy mass nuclei through the use of the (p,n) and (p,p') reactions at or near zero degrees with 100-200 MeV incident protons. Energy dependence in the isovector parts of the nucleon-nucleon interaction make the 100-200 MeV energy region particularly appropriate for such studies. The clean data from (e,e'), ('IT,'IT'), (p,p'), and (p,n) on high spin "stretched" states which have particularly simple structure has also been quite impor tant. The recent results contain important new information on the nature of the spin dependent forces in nuclei. These in turn are inherently related to the properties of the nuclear mesonic field and the underlying quantum chromodynamics.