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Below is a link to a youtube video of ISU's GEM detector. The detector contains 3 GEM foils and has an Argon-CO2 mixture of 90/20 flowing through it. The Drift voltage is about -3200 Volts and the GEM voltage is about -2900 Volts. Signal sizes are about 5-15 mV after being filtered and amplified.

A collection of materials related to the use of Gas Electron Multipliers (GEMs) in ionization chamber.

Vendors for parts
GEM HV Distribution Network


Laboratory for Detector Science



GEM Foil Cleaning Methods

GEM Foils Framing


At 25 C, 101.3kPa of and ideal gas = 24.47 Liters

Norco Gas quote

Part # P103535VAR = $50 portable bottle of 65% Ar 35% Ethane (10 day lead time)

Part # NLB417 = $75 regulator for flammable gasses flow rate is 0.5 L/hr.

Idea to check GEM foils

See if you can measure the current difference between a good and bad GEM foil using by putting 300 Volts across the leads with a digital volt meter set to measure the current (ie put one lead from the HV power supply onto the DVM and then the other DVM lead onto the GEM foil). Set the DVM to mV scale and don't set it to measure current. The DVM has a 10meg input impedance, so if its voltage range is instead used as a current meter, the 200mV range is the same as a 20 nanoamp range. So if the DVM indicates 1mV, it is actually measuring 100 picoamperes.

12 Volt power supply system.