EDM Precursor Run II: First electric dipole moment measurement of the deuteron with the waveguide RF Wien Filter

The second precursor run took place in spring 2021. Several improvements had been applied before and during the run: the alignment of the COSY had been surveyed and corrected, the beam position monitors had been calibrated by beam based alignment, the new JEDI polarimeter had been put into operation, monitoring of the COSY operation parameters had been improved and the rf Wien filter had been extended by a fast, high power switching system to allow the operation on individual bunches. The latter allows to run the phase-lock feedback on an undisturbed bunch and, thus, to separate the originating from the feedback system from oscillation induced by the rf Wien filter. Consequently, the experiment was done with two well separeted bunches in the ring. In addition, the solenoid from the 2 MV electron cooler was used as an additional spin rotator to study effectes from solenoids in both straight sections of COSY.

The data from both precursor runs are currently analzed in parallel to achieve a consistent picture. Preliminary results have been presented at several occasions. Please check the talks and proceedings section in the publication section.