The polarized target station at GKSS

The HIGS frozen spin target

“…After extensive tests of the refrigerator at room temperature, the refrigerator was first cooled down with 4 He and reached 1K at the target area. After this, a mixture of 3 He/ 4 He (ratio around 50/50) was circulated and with about 15% of the volume introduced, temperature in the mixing chamber was 270 mK. At this point the test was stopped because of running out of liquid 4 He.…”

“…The heart of HIFROST is a dilution refrigerator which we rebuilt from the one originally designed by T. Niinikoski [2] and used at CERN and subsequently at GKSS (now HZG) polarized target system, Germany [3]. Main modification was to install a new mixing chamber and new thermal sensors.…”

“…HIFROST has three gas storage tanks for 3 He, 4 He, and a mixture of 3 He and 4 He for experiments. For cool down to test instruments, two tanks were filled with pure helium-4 (99.97%) gas, while one tank has gas mixture.…”

“…We repaired and modified to make the pumping system for HIFROST. The gas/liquid/vacuum control system consists of the 3 He and 4 He pumping system, IVC/OVC, filling/flushing gas manifolds, and the LHe transfer line. Since the space to set up experimental equipment at HIγS is limited, part of the HIFROST system is located outside a 2 feet thick wall; 3 He and 4 He pumping system.…”

“…The gas/liquid/vacuum control system consists of the 3 He and 4 He pumping system, IVC/OVC, filling/flushing gas manifolds, and the LHe transfer line. Since the space to set up experimental equipment at HIγS is limited, part of the HIFROST system is located outside a 2 feet thick wall; 3 He and 4 He pumping system. The LHe transfer lines designed by us and fabricated by Cryofab, Inc. were installed and successfully transferred the liquid during our initial cool down.…”