Room Temperature PMT Housing ••••ISS photomultiplier tubes housings are compact units designed for both photon counting and frequency-domain data acquisition; they are coupled to the ISS spectrofluorometers through a M28x1 threaded flange. An adapter for coupling the PMT housing to a 10 mm fiber bundle is available.
The housing is designed for side-on photomultiplier tubes (model R928 by Hamamatsu and socket-compatible PMTs). The housing includes the high voltage power supply operating up to 1,200 Volt and requires a ±15 V, DC voltage for operation. In photon counting mode of operation, the PMT housing operates at maximum voltage. In analog mode of operation, the voltage can be changed manually through an external potentiometer positioned on the housing; or, automatically, through the computer. The latter form of control requires a D/A converter circuitry, a standard feature on all the ISS spectrofluorometers.
The frequency response of the housing is up to 700 MHz. In operation, the effective frequency response is determined by the PMT utilized for detection; Selected PMTs Model R928 feature a frequency response up to 600 MHz. The radiofrequency signal is injected through a BNC jack located on the back panel of the PMT.