<i>Cosmic Rays and Noise Counts from Internal Counters.</i></font>

Cosmic Rays and Noise Counts from Internal Counters.
<font color="DarkRed" size="5"><i><b>192 chambers M3R4 passed the tests</b></i></font>

192 chambers M3R4 passed the tests

Noise counts per 1 sec averaged over 48 channels at Thr =8.5fC and Thr=10fC
Table presents counting rates (counts per 100 sec) averaged over 24 pads in bi-gap AB or in bi-gap CD measured with Thr=16fC in all channels applying HV=2550V at one of the gaps (A,B,C,D) while the other gaps are at HV=0.
Also presented are the noise rates (counts per 1 sec) averaged over 48 pads (in bi-gap AB and in bi-gap CD) measured at HV=0 in all gaps with Thr=8.5fC and with Thr=10fC in all channels.
The thresholds were set individually for each channel according to the relation:
 Thr(reg.units)= Thr(fC)*S(reg.un/fC)-OFFSet(reg.un)+Thr_Max(reg.un). Here,
Thr_Max is the threshold at Maximum of noise rate;
OFFSet=17 reg.units (corresponding to 40mV);
S=3.40 reg.units/fC is the charge sensitivity (corresponding toSens=7.5mv/fC accepted for M3R4 chambers);


HV(ON) HV(OFF)
Chamber HV(A)=2550
GapAB		 HV(B)=2550
GapAB		 HV(C)=2550
GapCD		 HV(D)=2550
GapCD		 Thr=8.5fC Thr=10fC Atm.Pres. Date Plots Status
32 475.3 454.8 465.4 450.5 3239.5 155.9 Pa= 961 mb 22-JUN-07
Fig.1 Counts distribution over pads in bi-gap AB (odd channels) and in bi-gap CD (even channels) at various HV combinations:
Left_Up: HV(A)=2550V; HV(B,C,D)=0;
Right_Up: HV(B)=2550V; HV(A,C,D)=0;
Left_Down: HV(C)=2550V; HV(A,B,D)=0;
Right_Down: HV(D)=2550V; HV(A,B,C)=0;
Thr=16fC in all channels. Measurements time 100 sec.		 Fig.2 Counts distribution over pads in bi-gap AB (odd channels) and bi-gap CD (even channels) at HV=0 in all gaps
Thr=8.5fC (upper plot) and in Thr=10fC (down plot) in all channels. Measurements time 1 sec.
For comments, contact: Petr.Neustroev@cern.ch