| 摘要 |
PURPOSE:To obtain a detector whose inner tube member has a high machining precision and whose input/output terminals can be joined easily, by a method wherein a stem member, the inner tube member and an insulating plate are formed of free-machining ceramic while a cover member and the input/output terminals are formed of an iron-nickel alloy. CONSTITUTION:A vessel having a Dewar structure is constructed by using free-machining ceramic whose heat conduction loss is small and which can be machined with high precision, and by using an iron-nickel alloy which has a thermal expansion coefficient approximating to that of said ceramic. Herein an inner tube member 4 is formed precisely by cut machining, so that the matching with the sizes of a cooling unit can be attained easily. A cover ember 6 can be formed on the iron-nickel alloy. Accordingly, an excellent mechanical strength is attained and high reliability can be secured even when strict vibration-proof and shock-proof properties are demanded. Since the thermal expansion coefficients of these materials approximate to each other, moreover, the security of airtightness of joined parts against a change in temperature can be maintained for a long period. |
