comments on 2mm mwpc pitch
DESCRIPTION
Comments on 2mm MWPC pitch. W. Riegler, December 2002. Impact on specifications, guard wire and some other parameters. r a : anode wire radius V a : anode wire voltage : ion mobility q: charge per hit R: rate/cm 2 r c =(s/2 ) Exp(h/s) equivalent cathode radius - PowerPoint PPT PresentationTRANSCRIPT
Comments on 2mmComments on 2mmMWPC pitchMWPC pitch
W. Riegler, December 2002
Impact on specifications, guard wire and some other parameters
ra: anode wire radiusVa: anode wire voltage : ion mobilityq: charge per hitR: rate/cm2
rc=(s/2) Exp(h/s) equivalent cathode radius
Ea=Va/(ra ln(rc/ra)) anode wire surface field
Ec= Va/(s ln(rc/ra)) cathode surface field
t0= ra2 ln(rc/ra)/(2Va) signal tail
V=Rsh2q ln(rc/ra)/(4Va0) voltage drop due to space . charge effect
Details: LHCb-muon-2000-060
Ea (Gain105): 262.39kV/cm Va: 2750V (3150) V 0.87 Ec: 6.18 (8.24) kV/cm 0.75 rc: 16.15 (44.86) mm ln(rc/ra): 6.982 (8.00) 0.87 t0: 1.50 (1.50) ns 1 V Voltage drop due to space charge: factor 1.33 larger, negligible Specs:
When does the wire surface field differ by 1% i.e. the gas gain differ by 20% ? Gap: 88(75) m 0.85 single wire X: 130(90) m 0.69 single wire Y: 310(250) m 0.81 wire plane Y: 330(300) m 0.91
No Guard Wire: 301(325), 269(277), 263(266), 262(263), 262.3(262) kV/cm
200m Guard Wire: 70.4(76.5), 251(249), 260(260), 262(262), …. kV/cm
Parameters and Specifications for h=2.5mm,ra=15m, s=2(1.5)mm
ConclusionsConclusions
With respect to specifications, rate capability, signal tail and guard wire issues the 2mm pitch doesn’t have any drawbacks compared to the 1.5mm pitch.