NaI(TL)Scintillant BG0 Scintillant CsI Scintillant Photomultiplier tube GDB   　　Photomultiplier tube (GDB)produces photoelectron through photon's incidence to photocathode, then the photoelectron enters multiplication system through inputting electron optical system, and finally forms output current or voltage after twice emission, many times multiplying and collecting by anode, which is widely applied to the fields of photon counting,scinticounting and oil exploration.The photomultiplier tubes applied to oil exploration include GDB－21，GDB－30，GDB－38，GDB－40，GDB－44,etc with the temperatures of 125。C and 150。C.The cathode sensitivity（normal temperature）of GDB－30,GDB－40 pipe is 9μA/1m,and that of GDB-21,GDB-38 pipe is 10μA/1m; The anode sensitivity(normal temperature) of GDB－30、GDB－40 pipe is 30μA/1m when the Max. voltage is 1800V, and that of GDB－21pipe is 100A/1m when the Max. voltage is 1250V and that of GDB－38 pipe is 200A/1m when the Max. voltage is 1250V. At the temperature of 150。C, when the plateau length of output voltage is larger than 150V, the pulse amplitude reduces 50% under the high temperature conditions.