GEM Foil Cleaning Methods

• 1). First method(suggested by Rui De Oliveira)

When the leakage current is below 200 nA we just clean the GEMs with sprayed DI water (DI water 10Mohms quality)

• 2). The basic procedure followed for cleaning GEM foils suggested by Bob Azmoun, a researcher in the PHENIX Group at Brookhaven National Lab. Media:Georgia_3GEM_Detector_UR_Report_F04-1.pdf, Media:UG_Research_Report_David_Fall_04-1.pdf.

The procedure, which is done under a laminar flow hood, is outlined below:

1.Spray down the foils (always at “grazing incidence”) with dry N2

2.Spray down the foils with ethyl-alcohol until foils are completely drenched, using a Windex-type dispenser spray

3.Before the ethanol has a chance to air dry (which could absorb particulate deposits from the air onto the GEM surface), quickly spray down the foils again with dry N2 (again, always at “grazing incidence”)

One should keep in mind that after this process the GEM impedance should drop dramatically, due to the conductivity of the remaining alcohol. However, usually after 5hrs of purging with dry gas, the impedance returns to its original value. "

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