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Theory Of Operation Teledyne API M100E Analyzer Operation Manual
238
11.4.3. PHOTO MULTIPLIER TUBE (PMT)
The M100E uses a photo multiplier tube (PMT) to detect the amount of fluorescence created by the SO
2
and O
3
reaction in the sample chamber.
PMT Housing End Plate
This is the entry to the PMT Exchange
PMT Preamp PCA
High voltage Power Supply
(HVPS)
PMT
PMT Cold Block
Connector to PMT
Pre Amp PCA
12V Power
Connector
Cooling Fan
Housing
TEC Driver PCA
PMT Heat Exchange Fins
Li
g
ht from Reaction
Chamber shines
throu
g
h hole in side
of Cold Block
Insulation Gasket
PMT Power Supply
& Aux. Signal
Connector
PMT Output
Connector
Thermo-Electric Cooler
(TEC)
PMT Temperature
Sensor
O-Test LED
Figure 11-14: PMT Housing Assembly
A typical PMT is a vacuum tube containing a variety of specially designed electrodes. Photons from the reaction
are filtered by an optical high-pass filter, enter the PMT and strike a negatively charged photo cathode causing it
to emit electrons. A high voltage potential across these focusing electrodes directs the electrons toward an array
of high voltage dynodes. The dynodes in this electron multiplier array are designed so that each stage multiplies
the number of emitted electrons by emitting multiple, new electrons. The greatly increased number of electrons
emitted from one end of electron multiplier is collected by a positively charged anode at the other end, which
creates a useable current signal. This current signal is amplified by the preamplifier board and then reported to
the motherboard.
04515F DCN6048