Speaker
Description
The CP violation beyond the standard model is not only physically interesting on its own, but also a key for understanding the baryon asymmetry in the current universe. In a low energy region, instead of directly probing it, many efforts to search the violation of time-reversal symmetry(T-violation) continue in various physics systems with high sensitivity. Among those, neutron-induced compound nuclear reactions are interesting because the enhancement of parity-nonconservation effect(PNC) has been found in many compound nuclear states. Particularly, in the neutron resonant absorption in Lanthernum nuclei(La) at 0.75eV, the enhancement is so great that it reaches 10^6. This enhancement for the PNC can be also expected for the T-violation from recent experimental results and theoretical calculations. Additionally, this system is sensitive to a different physical parameter indicating the magnitude of the T-violation from the neutron EDM, so that it is also attractive in terms of a different search region. Thus, the NOPTREX collaboration is planning the T-violation search with La targets as a first attempt. One big issue is the development of a polarized La target because polarized targets except for proton and deuteron have not been realized yet as a practical use. In this presentation, we will introduce the overview of the first stage of the T-violation experiment, Phase-I, and report current status in the NOPTREX project.
