PIONIC MODES STUDIED BY QUASIELASTIC $(\vec p, \vec n)$ REACTIONS

Abstract

It has long been expected that the pionic modes show some collective phenomena such as the pion condensation in the high density nuclear matter and its precursor phenomena in the ordinary nuclei. Here we show an evidence of the precursor observed in the isovector spin longitudinal cross sections IDq of the quasielastic 12 C, 40 Ca ( p, n) reactions at Tp = 346 and 494MeV with the momentum transfer q =1.7fm