A storage ring EDM polarimeter

Abstract

The search for electric dipole moments (EDM) of elementary particles is one of the hot topic in contemporary particle physics. The method to measure charged particle EDMs (p,d) is to observe the time development of a polarized beam in a dedicated storage ring (srEDM). This requires a new polarimeter with a special target system which is under development at COSY-Juelich.The particle detector consists of the two layers: a plastic scintillator for ?E and an inorganic LYSO crystal as a calorimeter. Both systems are readout by multi-pixel SiPM (silicon photo multiplier) arrays. SiPMs operate at significantly lower supply voltages compared to the traditional multi-stage vacuum tubes, simplifying detector construction and operation. The developed calorimeter modules operate at voltages up to 30 Volt. For this purpose a modular, high precision voltage supply has been developed together with slow control and voltage monitoring systems. The fully assembled calorimeter part of the polarimeter has been successfully tested together with its high speed and high-resolution sampling ADC-based readout. All test have been carried out using solid block target. However, the final polarimeter will include a ballistic target system which will be shooting point-like diamond pellet through the beam. The movement of the pellet will be precisely tracked in three dimensions and synchronized with the data acquisition system. This will allow us to reconstruct the polarization profile of the beam. Currently, the mechanical and electrical systems for the pellet target are under development.Recent achievements and experimental results of this project are summarized and discussed in this paper.