The typical photomultiplier tube (PMT) is based on the effect of multiplication of electrons in vacuum when driving in strong electric field: getting on the intermediate electrodes (dynodes), the electrons are pressed to the additional number of electrons. The primary electrons are generated as a result of the external photoelectric effect in absorption of light on the photosensitive layer (cathode).
Although state-of-art technology has greatly miniaturized PMT, this device is still large enough due to the fact that it is based on vacuum glass container.
In most applications photomultiplier tubes are working at room conditions.
For better performance PMT are produced with cooling arrangement.
The reason for the use of cooling is related to the temperature dependence of properties, namely dark current of photosensitive cathodes, which are semiconductors. At cooling the dark current can be significantly reduced, and this in resulted in the characteristics of the PMT - signal/noise ratio.
In commercial PMTs, thermoelectric Peltier coolers (TECs) are used for this purposes. Because the design of the PMT is massive, TECs should be used for large linear dimensions. Because of the massiveness of the design and the inability to reduce parasitic heat loads, it is very difficult to create a multistage thermoelectric cooling system design. Therefore, in most cases, the cooling is carried out by single-stage TECs with typical operating temperatures -20… -25°C.
RMT produces TECs suitable for thermal stabilization of PMTs.
To improve the homogeneity of temperature across the surface of the TEC, it is made with use of aluminum nitride ceramics having high thermal conductivity.
To select a suitable solution and the optimal TEC for an application, the supporting is available at RMT’s website. For detailed modeling and calculations the company RMT provides our customers by free software or .And for advice and assistance.