Charged-particle tracking for neutron-deuteron breakup

Abstract

Particle tracking software has been developed to measure the energy of protons scattered in the breakup process d(n, np)n. The nd breakup experiment is performed at the Weapons Neutron Research facilities at Los Alamos Neutron Science Center. In order to fully define breakup kinematics for the stationary deuterium target, the following are measured: incident neutron beam energy, scattered proton energy and angle, and one of the scattered neutron angles. The proton energy is determined using a permanent magnet spectrometer, consisting of two permanent magnets placed between two wire chamber detectors. A particle tracking code uses the particle hit positions in the wire chambers to determine the proton's curvature (and hence deduce its energy) as it passes through the magnetic field of the magnets. Monte Carlo simulations show that the kinetic energy resolution is better at lower proton energies, when the magnetic field bends the particle more. The ultimate goal of the experiment is to measure the five-fold differential cross section to look for effects of three-nucleon forces.