Design and construction of a Modular NaI(Tl) Detector Array for use in the Parity-and Time Reversal Violation Measurements for NOPTREX

The goal of the NOPTREX experiment is to probe the Standard Model via parity and time reversal invariance violation in low energy neutron-nucleus resonances. An array of modular NaI(Tl) detectors with fast timing and good energy resolution is needed to measure asymmetries in the total forward scattering cross section, and in the gamma from neutron capture on deuterium. These detectors will be designed to operate in both pulse and current modes. A search for parity violation in A>120 nuclei and also in the reaction n+d -> t+gamma is being carried out in the FP12 instrument at the Los Alamos Neutron Science Center. We will discuss an efficient design of the detectors, electronics, and magnetic shielding,

as well as progress on the construction and characterization of the array.