Accelerator Division

# Towards the EDM Polarimetry - Tests of LYSO Modules

Various symmetries are one of the most basic concepts in modern physics. Every conservation law is related to some symmetry. However, it is known that some of the symmetries are violated in weak interactions. One of the most important nature symmetries are parity (P), time reversal (T) and charge-conjugation (C). Confirmation of breaking one of those symmetries in strong interactions would have significant impact on strong interactions theory and on our understanding of the Universe. Also, particle-antiparticle asymmetry in nature is strictly connected with T symmetry breaking which should occurred in an early time of the Universe. Up to now systematic searches of T violation have been done with use of neutral particles. For charged particles, due to special difficulties of applying electric fields on charged particles, only indirect experiments, with limited precision, have been performed. Just recently, an alternative approach has been proposed. Using storage rings to accumulate polarized particles it is possible to measure electric dipole moment (EDM) - a quantity which is strictly related to T and P symmetry. To undertake measurement of EDM of charged particles, new international collaboration JEDI has been established in 2011. JEDI (Jülich Electric Dipole moment Investigations) links together researchers from all over the world. The most important institutions involved are: Forschungszentrum Julich, RWTH Aachen, Tbilisi State University, SPSC Grenoble, University of Ferrara, Jagiellonian University, Joint Institute for Nuclear Research in Dubna, Institute for Basic Science in Daejeon. The main objective of JEDI is to build a dedicated storage ring for a precise experiment, which allows measuring proton and deuteron EDM with a precision of $10^{-29}$ e cm. Idea of the experiment bases on a measurement of vertical beam polarization, caused by EDM interaction with electromagnetic fields in a ring. However, the expected effect is extremely small, it observation put special requirements to the experiment apparatus. One of the challenges is a development and construction of a new type of polarimeter with very high precision and sensitivity.