1. 6 Feb. 2003 (update) A.P.Kashchuk (LNF/INFN, on leave from PNPI) 1 Triple GEM is the best candidate for station M1 regions R1/R2 Triple GEM has better Cluster size 1.1-1.2 High rate capability Systematic studied aging if compare to MWPC

2. 6 Feb. 2003 (update) A.P.Kashchuk (LNF/INFN, on leave from PNPI) 2 Remarks for further improvements of the Triple GEM detector w.r.t. M0 prototype tested in October 2002 1.Cdet must and can be reduced from 50pF to 5pF (change design), then ASDQ chip can be used effectively (better than ASDQ++ and CARIOCA): ENC=1200+70e/pF=1550e (RMS) x 4 =>>> 1fC (threshold) compare: at present design with ASDQ++ (CARIOCA will be similar) ENC=2000+40e/pF=4000e (RMS) x 4 =>>> 3fC (threshold); 2.Further S/N improvement if double signal by OR-ing on the amplifier input (instead to readout single detector to own amplifier, one can use 2 amplifiers for reliability, but read double signal to each one, output select by DIALOG); 3.As it is needed for GEM, ASDQ chip has discharge protection on the negative input: 550pF at 3kV, 1.5mJ. CARIOCA will need external protection, and additional noise of the protection board will be added: 10pF and 15 Ohm =>> 500e; 4.Guard traces must be added between readout pads to reduce crosstalks from pad to pad (ASDQ has Rin=300 Ohm); 5.Full charge (50fC in average from 6mm gas gap) will be collected by ASDQ. It is equivalent to gas gain 10 4.

3. 6 Feb. 2003 (update) A.P.Kashchuk (LNF/INFN, on leave from PNPI) 3 Where this ‘blocking’ capacitor?

4. 6 Feb. 2003 (update) A.P.Kashchuk (LNF/INFN, on leave from PNPI) 4 Cathode Drift gap GEM1 GEM2 GEM3 Anode Transfer1 Transfer2 Induction gap ‘Blocking’ capacitor ( defines the current return path) in chain To be cancelled or minimized To be maximized

5. 6 Feb. 2003 (update) A.P.Kashchuk (LNF/INFN, on leave from PNPI) 5 Cdet=5pF, Cbl=100pF Cdet=50pF, Cbl=100pF Cdet=5pF, Cbl=1000pF Zoom x100 ‘Blocking’ capacitor ( defines crosstalks) x1 Simplified GEM (induction gap) spice-model Signal (green) Crosstalk (blue/red) at various conditions Neighbor pads 2D array Cdet=5pF, Cbl=0 High crosstalk (even with opposite polarity) bad! Crosstalks are equal on all pads! tr=100um/ns tf=RampCin

6. 6 Feb. 2003 (update) A.P.Kashchuk (LNF/INFN, on leave from PNPI) 6 Cdet=5-50pF, Rin=300, Cbl=1000pF x10 Cdet=5-50pF, Rin=30 x10 Signal (green/ red) Crosstalk (blue) at various conditions One can see from here, that Triple GEM has to be optimized Cdet=5pF, Rin=300, Camp=5-50pF, Cbl=500pF x100

7. 6 Feb. 2003 (update) A.P.Kashchuk (LNF/INFN, on leave from PNPI) 7 Cbl=1000pF Cdet=Camp=5pF, Ramp=300 Attention: crosstalks to pads from the GEM-foil Cbl=100pF Cbl=10pF Noise source on GEM-foil (e.g.history) Qin=50fC Noise=blue/top Signal=green/bottom