Research will be conducted on fundamental problems in nuclear reactions at the major nuclear physics accelerators in this country and abroad. These include LAMPF, in Los Alamos, New Mexico, TRIUMF, in Vancouver, Canada, SATURNE II, in Saclay, France, and LEAR, in Geneva, Switzerland. Their recent work has shown that the nucleus is unexpectedly receptive to being excited by the transfer of spin from the projectile when the projectile loses more than about 20 MeV in the scattering process. They will continue this work to determine whether this collective action of many nucleons is truly a general feature of nuclei over the entire periodic table. They will pursue their investigations of pion absorption mechanisms in nuclei. The pion is the basic carrier of the nuclear force; when it combines with a neutron or proton, it can form another particle, the delta. The researchers will also explore reactions in which nuclear correlations seem to change the mass of the delta inside nuclei.
