| 摘要 |
A cryogenic cell comprises an external annular chamber 5 adapted to be maintained under vacuum and partially enclosing an heat shield 2 surrounding and spaced apart from the metal block 1. The space 3 between the heat shield 2 and the metal block 1 also forms an annular chamber adapted to be maintained under vacuum. The heat shield 2 has a relatively thin base and sidewall and a relatively thick exposed upper collar having a well 7 therein leading to the top of the metal block 1. The collar, well 7 and top of the metal block are adapted to receive a "cold finger" to lower the temperature of the shield and block. The block 1 is connected at its lower end to a further chamber 10 suitable for the reception of a gamma radiation detector. The cryogenic cell is suitable for keepig the semiconductor detector of a neutron activation analysis borehole logging tool within the required low temperature range. <IMAGE> |
