Speaker
Description
The COMPASS experiment at CERN used a transversely solid polarized deuteron target with a muon beam to measure the TMD PDFs in SIDIS in 2022.
The target system consists of a 50 mK dilution refrigerator, a 2.5 T solenoid magnet, and three sets of 70 GHz microwave systems. Solid $^6$LiD beads of the target material were contained in 3-target-cell of 30-60-30 cm long with 3 cm in diameter. The target material was produced for the first phase of COMPASS which started data taking in 2002. The longitudinal polarization of the target is obtained by the DNP method with gunn diode oscillators which are newly installed. We collected data from June to November 2022.
The polarization was determined with 10 NMR coils on the cells.
The polarization was calibrated with the thermal NMR signal at three different temperatures (1.0, 1.2 and 1.5 K).
The analysis of the thermal equilibrium NMR signal is essential to determine the polarization during DNP.
We will present the results of the analysis of the thermal deuteron NMR signals, the relaxation times during the data taking as well as performance of the new microwave synthesizers.
