Principle of Operation Determine muon position by interpolating the charge on 3 to 5 adjacent strips using ratio algorithm: Precision (x-) strip pitch ~ 5mm Measure Q 1, Q 2, Q 3 … with signal/noise=150/1 to get x ~ 60-80 m. Human hire diameter ~100 m. Second set of y-strips measure transverse coordinate to ~ 1 cm. Position accuracy unaffected by gas gain or drift time variations. S = d = 2.50 mm W = 5.308 mm 0.8Ar+0.2CO 2
Beam test setup layout at X5 high radiation facility P =120 GeV/C Lead absorbers of different thicknesses were used to vary the background flux intensity. ←
Signal shape and fitting The bipolar function was used to fit the signal: z = (t-t 0 )/ n=12 - the parameter of amplifier integration, t 0 - signal start position - signal width signal has been digitized at 20(40)MHz Clock time distance between time slices 50(25)ns pedestal extracted
Landau distribution Charge induced in ADC counts: Q = Q max +Q right +Q left
Position resolution and inefficiency Inefficiency: Position resolution in 2 nd and 3 rd gaps defined as (two chambers involved), where - width of the Gaussian fit of over ±0.3mm
CSC one layer resolution and inefficiency as a function of background radiation rate Run 99 Run04
Summary stand alone test beam at X5 During the beam test the chamber + electronics at 20 MHz clock showed the expected performance. One layer inefficiency is found to be 5% without radiation and 24% at the maximal expected LHC background rate (safety factor of 5) 4.2 kHz/cm 2 No calibration used. The results can be considered as conservative estimates (not worse then) for efficiency and resolution.