SKS Cryogenic System Home Page

News (Upper is newer)

Operation No. 68 will run from Jun. 20 to Jul. 10 for E521. ('03/06/13)
Summer maintenance schedule (kek.jp domain only) is available. ('03/06/10)
Entering N-counter hall is always limited under radiation safety control.('00/04/10)

Introduction

The cryogenic systems of a sector type superconducting spectrometer magnet SKS was constructed for nuclear physics experiments at 12 GeV PS North-hall of KEK in 1991. The total weight of the magnet is 280 ton with the iron yoke. A mediun-size refrigerator, which has a refrigeration power of 300 W at 4.5 K with liquid nitrogen precooling, was required to cool down the magnet to 4.2 K and keep it in the same temperature. In addition to the medium-size refrigerator, a small-size G-M refrigerator was installed on a service port of the helium vessel to cool the 80 K and 20 K thermal insulators which are surrouding the superconducting magnet inside the vacuum vessel. These systems make the heat leak as small as possible in cooperation together. The other feature is that the helium transfar line between the magnet and the medium-size cold box is flexible to make the magnet be movable in large angle from -10 degree to +40 degree to measure angular distributions for nuclear physics experiments. For this purpose, some special devices were required. The all states of cryogenic systems including the magnet and the medium-size and the small-size refrigerators are monitored and full-automatically controlled at the central control room with large process controllers and some computers.