Details of a water target used in a high-current application for a neutrino-physics experiment and the direct measurement of the incident proton beam by the induced change in the water conductivity

Abstract

A water target was constructed for use in a low-energy neutrino physics experiment at the Los Alamos Meson Physics Facility. For 800 MeV incident protons, a water target may be close to optimal in the production of positive pions that subsequently decay in flight, yielding muon neutrinos, especially if used in conjunction with a pion-focusing device. We discuss the special features of the beam vacuum window, the target and water cooling system that were designed to withstand damage from radiation and mechanical stress caused by the large proton currents used in the experiment. Our target also included internal monitors to measure changes in water conductivity induced by the passage of the proton beam. This novel monitoring technique permitted a direct measure of the intensity of protons inside the target and gave a measure of the beam alignment.