Minutes from target meeting held March 20 2015 in 892-2-009 These minutes are available also from: http://wwwcompass.cern.ch/compass/detector/target/Minutes/2015/ a) On Monday leak test helium-3 roots pump WKP4000 internal water cooled heat exchanger. At level 7 10^-4 mbar l/s no leaks found. b) Assemble new proton free plastic target cells and insert into Kevlar tube together with central microwave stopper and helium-3 filling tube. On Tuesday afternoon cool down target cells in LN2. Load 1107 g of colored gravel into upstream cell. Removal of the filling caps is sometimes difficult in LN2 and the caps need to be rotated to correct direction. Norihiro: when cooling from 300 K down to 80 K diameter of the target cell component shrinked from 40.0 mm to 39.0 - 39.4 mm. In the longitudinal direction the new target cell component length shrinked from 102.0 mm to 101.3 - 101.5 mm. c) Disassemble target cells on Wednesday. Paint the nomex honeycombs in the central microwave stopper with graphite paint. Reassemble the target cells together with microwave stopper and helium-3 filling tube. d) On Thursday pressurize dilution cryostat mixing chamber to 880 mbar and let air into helium-3 roots pumps. Drain Pfeiffer oil P3 from all the pumps and fill in new P3 oil. The oil change was finished in Friday afternoon. The oil color was clear for all the pumps except two of them. The downstream side of WKP4000 had a brownish color in the oil. The WGK125SP had small metal particles in the oil at the downstream side. e) Fabrice: test magnet safety system last week. Differential voltage detected in solenoid end compensation coils triggered the coil heaters. Last Friday nominal 2.5 T in solenoid and 0.63 T in dipole were tested. The 2.5 T solenoid field was kept during 3.5 hours. The power circuit inside the racks has been improved since last year. The Direct Current Current Transducer (DCCT) is now made from solid brass bars and the operation temperature at nominal current has decreased from 90 C to 60 C. The hot spots were checked with infrared camera and the temperature is monitored with a temperature sensor. Test field rotation from longitudinal solenoid field to transverse dipole field on Wednesday. At 1.5 A/s ramping down rate the power dissipated in protection diodes is a little too high. New ramping rate 0.8 A/s will be used to keep the diode temperatures lower. On Thursday test field rotation from 2.5 T solenoid field to 0.63 T transverse dipole field. The minimum total field during the operation was always more than 0.5 T. Test full field rotation cycle from +2.5 T to +2.5 T in about 50 minutes. The plan is to test full field rotation cycle from +2.5 T to -2.5 T manually. Next step is to test automatic field rotation script and add this feature to the magnet SCADA system (ICE controls). Communication between the magnet control system and NMR DAQ needs to be tested. This is needed during the thermal equilibrium calibration, where the solenoid current is shifted +-10 A for baseline data taking. In addition recovery procedure from slow discharge is planned. This would help to keep the target polarization in case of a minor problem in the magnet like a short power cut. f) Christophe: the magnet cryogenic and power system can now be monitored from the COMPASS DCS system.