Nucleon charge-exchange reactions at intermediate energies

The nucleon charge–exchange reaction is investigated as a probe of isovector modes of nuclear excitation at both small and large momentum transfer. The calculated and extracted properties of the isovector nucleon–nucleon interaction are discussed and illustrated with an emphasis on incident energies in excess of 100 MeV. Particular emphasis is placed on spin observables and the roles played by different parts of the nucleon–nucleon coupling in their determination. Recent measurements of transverse polarization transfer at 0° in the charge-exchange continuum are compared with distorted wave impulse approximation calculations using random–phase approximation transition densities.