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Amplifier Discriminators
Photon counting is the fundamental method for extracting the maximum information from a weak light signal. Coupling an amplifier-descriminator to a photomultiplier achieves this.
An amplifier-discriminator combines a fast amplifier and a fixed-threshold discriminator with an overall sensitivity of approximately one millivolt. With the gain of the photomultiplier optimised, photon counting with a high signal to noise ratio and stability can be achieved up to count rates of 100 MHz.
ET Enterprises offers a range of amplifier-discriminators with output logic levels compatible with commercially available counters. Please refer to the section on the CT2 counter/timer module. A cable, LEADAD6CT2, is available to connect the AD6 to the CT2, and powers the AD6.
The range is summarised in the table below.
| amplifier descriminator selection guide | |||||
| type | input impedance ohms |
input threshold mV |
pulse pair resolution (ns) |
output pulse |
power requirements |
| AD1 | 50 | -1 | 100 | ECL | +5V, 25mA -5V, 100mA |
| AD2 | 50 | -0.5 to -2.5 | 25, 40, 80* | ECL | +5V, 25mA -5V, 100mA |
| AD3 | 50 | -2 to -5 | 10 to 100 | ECL | -5V, 65mA |
| AD6 | 50 | -2 | 24 | TTL | +5V, 10mA |
| AD7 | 50 | -2 to -5 | 24 | TTL | +5V, 10mA |
| * preset with external links, please specify when
ordering, easily reset |
Amplifier-discriminators are available as modules in metal cases with BNC input connector and 9-way D-connector output and LV power connection, view an outline drawing here. The AD7, which is pcb mounting, is supplied in a metal case. View an outline drawing here. Examples are also shown in the photograph on this page. They can also be incorporated into housings; please refer to the section on housings.
Read about amplifier-discriminator options on this page.