Results of the first experimental search for the excitation of discrete final states following exclusive (-,p) reactions are reported. The measurements include differential cross section at thetalab=25°for (,p) reactions on Mg24, Al27, Ca40, and Ni58 at T=120 MeV and (-,p) on C12 at T=145 MeV. The (-,p) reactions yield peaks with d/d1 b/sr compared to 722 b/sr for peaks from (+,p) reactions. The shape of the continuum in an excitation energy range of 1040 MeV was found to be independent of pion charge and target. The ratios of (+,p)/(-,p) averaged over excitation energy and the ratios of the same reaction on different nuclei are presented. The magnitude of the proton yield in the low excitation continuum is more than 20 times larger for + than for -, which supports a two-nucleon absorption model including pion charge exchange.
ASJC Scopus subject areas
- Nuclear and High Energy Physics