Charge-exchange studies at the Los Alamos Meson Physics Facility – Weapon Neutron Research Facility

Abstract

The Los Alamos Meson Physics Facility – Weapon Neutron Research Facility has been used for (p,n) charge-exchange studies leading to a paper on the energy dependence of the nucleon–nucleon spin–isospin interaction at up to 800 MeV. Because of program changes connected with the use of the proton storage ring and the need for a "white" neutron source, a new facility for neutron time-of-flight studies of the (p,n) reaction up to 800 MeV has been designed. In addition, a proposed facility using the white source for (n,p) studies up to 200 MeV is being built. A brief discussion of the results achieved thus far from the (p,n) work is given. Specific plans for the (p,n) facility with a flight path of 250 m, as well as the design for the proposed (n,p) white source, are discussed. Initial results with the (p,n) line at 256, 600, and 880 MeV show that the time spread due to proton-drift distance results in roughly constant neutron resolution.