Comments on 2mm MWPC pitch

Comments on 2mm Comments on 2mm MWPC pitch MWPC pitch W. Riegler, December 2002 Impact on specifications, guard wire and some other parameters

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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 Presentation

Transcript of Comments on 2mm MWPC pitch

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.