One of the highest priority searches in astro/physics and cosmology is understanding the origin of the matter/antimatter asymmetry of the Universe. In 1967, Sakharov proposed three conditions necessary to generate such an asymmetry, one of which is the presence of charge conjugation (C)- and time (T)-violating processes. We do not yet know of enough T-violation present in the Standard Model to account for the size of the asymmetry--thus, additional searches for T violation are needed!
 
The Neutron OPtics Time Reversal EXperiment (NOPTREX) Collaboration aims to measure potential T-violation in elastic forward scattering processes occurring in neutron-nucleus interactions. In particular, we are interested in the interactions occurring when neutrons incident on a nuclear target are at ‘resonant’ energies, forming a quasi-bound state known as the compound nucleus. Due to the complex, many-body structure of the compound nucleus, we expect a large (~10^6) amplification of the potential T-violation signal; this, along with the nature of the energy scales that we are probing make the NOPTREX experiment complementary to other T-violation searches such as the neutron EDM.  In particular, NOPTREX offers a discovery potential to T-violating meson-nucleon coupling constants of several orders of magnitude above the current limits from neutron EDM experiments.

Some of these resonances are known to be parity violating interactions; because the proposed theoretical T-violating cross section is directly proportional to a P-violating cross section, precision spectroscopy of these resonances is of critical importance. In particular, the 0.74 eV p-wave resonance in 139La exhibits a ~10% P-violation effect, making it an outstanding candidate for the NOPTREX experiment.

We plan to measure this effect in 139La to 1% precision, improving upon previous (room temperature) measurements by using cryogenic targets to minimize Doppler broadening effects as well as running for a longer period of time to reduce the statistical uncertainty. This experiment is currently being conducted at LANSCE at FP12 in the Lujan Center. This talk will focus on the theory and experimental setup behind the NOPTREX T-violation experiment, as well as the setup, progress, and preliminary data analysis of the FP12 parity violation measurement taking place at LANSCE.