Signal detection electronics for a Multi-Wire Proportional Chamber

The Society of Physics Students (SPS) at Kennesaw State University is building a series of Multi-Wire Proportional Chambers as a tool to detect cosmic ray muons with the goal of doing muon tomography on large structures.

High-energy cosmic-ray muons passing through the chamber ionize the gas (in our case Argon/CO2 mix) and the resulting avalanche produces secondary ionization electrons which are deposited in the sense wires. The current pulse produced by this process is extremely small (on the order of nanoamperes) and also needs to pass through a row of capacitors which are used to isolate the high-voltage wires. this signal needs to be highly amplified in order to be detected.

The op-amp chosen is the AD8099. This op-amp operates at high frequencies necessary to allow the cleanest possible signal for detection while giving high enough gain to send to a comparator for digital analysis.

Once we have been able to separate the signal from the background electronic noise, we can fine tune the circuit by narrowing the bandwidth to the signal frequency. In addition to this the op-amp was simulated using LT Spice program to find the theoretical operational frequency.