The A111F is a high density version of the Amptek A111 Charge Sensitive Preamplifier and Discriminator.
The A111F features a Single In-line Package (SIP).
|Pin 2||Ground and Case|
|Pins 3 & 4||Threshold Adjust|
|Pin 4||Analog Monitor|
|Pin 5||V (+4 to +18 VDC)|
Weight: 1.6 g with leads cut to 0.100 inch (2.5 mm).
Increasing the threshold of the A111F beyond the x10 provided by shorting out Pins 3 and 4 can be achieved by an RC feedback as shown below.
Apart from unit to unit variation, the discrimination levels will be as follows:
|R = 50 k||C = 2.2 pF||x 17|
|R = 20 k||C = 3.3 pF||x 23|
|R = 5 k||C = 4.7 pF||x 40|
|R = 2 k||C = 6.8 pF||x 88|
Intermediate values can be obtained by adjusting the value of R.
Decreasing the threshold of the A111F beyond the nominal 5 x 104 electrons can be achieved by adding a resistor from Pin 4 to ground. A 300 ohm resistor will approximately double the sensitivity resulting in a threshold of 2.5 x 104 electrons.