Simulation of Light Collection for nEDM Experiment*

The search for the neutron EDM (electric dipole moment) plays an important role in nuclear and particle physics and since it will give direct evidence for the violation of time-reversal symmetry and for physics beyond the Standard Model.

The goal of the nEDM experiment at Oakridge National Lab is to further improve the experimental sensitivity by another factor of 100 compared to the current experimental limit.

My project is closely related to the signal (scintillation light) generated from the capture reaction of spin-dependent neutron and Helium-3. In this project, we try to improve the design for higher light detection efficiency. For this purpose, we perform a full-scale simulation of the measurement cell for the upcoming nEDM experiment using Geant4, in the order to optimize light output of the cell. In particular, I use experimental data from test setups to check the properties of various components in the simulation, such as light sources, the reflector tent, wavelength shifting fibers, wavelength shifting TPB and acrylic.  Afterwards, the experimental data are used to successfully validate full scale simulation of the test setups.  We are in the process of building a realistic simulation for the nEDM light collection cell for optimization studies.