| 摘要 |
PROBLEM TO BE SOLVED: To dissolve complexity accompanied by supply of liquid nitrogen, by connecting a liquid nitrogen production device and a liquid nitrogen storage part of a radiation detector with a supply pipe, and providing a control means for maintaining the storage quantity of liquid nitrogen in the liquid nitrogen production device and the liquid nitrogen storage part of the radiation detector larger than a certain amount. SOLUTION: A storage Dewar 8 of a liquid nitrogen production device 3 and a Dewar 2 of Ge detector 1 are connected with a supply pipe 10, and liquid nitrogen is supplied through this supply pipe 10. In the case the storage quantity of liquid nitrogen lowers than a certain level, the first control means, receiving a detection signal from a level meter 15, controls the operation of a compressor 9 and operation of the liquid nitrogen production device 3 so as to maintain the storage quantity of liquid nitrogen in the Dewar 8 over the level. In the supply pipe 10 connecting the Dewars 2 and 8, an electromagnetic value 11 is installed, which is controlled to open and close by receiving signals from a timer 12. A second control means for controlling the supply of liquid nitrogen from the Dewar 8 to the Dewar 2 is provided.
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