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BMC Cosmic Ray Test Stand Update, Dec. 2001, Steve Ahlen - Boston Univ.

BMC Cosmic Ray Test Stand Update, Dec. 2001, Steve Ahlen - Boston Univ. Gas system installed on Mod-0 (EIL-1) January 2001 Initial electrical tests January - March 2001 DAQ set up and debugged April - May 2001

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BMC Cosmic Ray Test Stand Update, Dec. 2001, Steve Ahlen - Boston Univ.

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  1. BMC Cosmic Ray Test StandUpdate, Dec. 2001, Steve Ahlen - Boston Univ. • Gas system installed on Mod-0 (EIL-1) January 2001 • Initial electrical tests January - March 2001 • DAQ set up and debugged April - May 2001 • Data taking on cosmic rays June - August 2001 • Data analysis September - October 2001

  2. BMC Test Stand XP-2020 phototubes scintillators Mod-0 concrete

  3. Mod-0 (EIL-1) on combs in clean room

  4. Cosmic Ray Test Stand

  5. Mod-0 on Test Stand

  6. Threshold = 60 mV flow = 100 sccm Threshold = 44 mV flow = 100 sccm Threshold = 44 mV, flow = 500 sccm for 2 days

  7. More timing corrections • Transit time along wire • Time of flight • Trigger time variations due to cable/electronics variations for bottom scintillator layer Previous corrections • TDC card initialization offsets (12.5 ns) • Clock (synchronization of scintillator and drift tubes) • Transit of light along bottom scintillator

  8. Exact tdc vs r for special cases TDC r(mm) r(mm) TDC 403 7.509 7.509 403 403 7.509 14.379 1050 403 7.509 403 7.509 403 7.509 0.639 159

  9. Time to distance function with correction factor 15 minutes data from mu062801a

  10. Old Track Fitting • Multilayer (4-tube) fits • determine the most likely position of the trajectory relative to the drift tube wire (i.e. left or right) • consider all 16 possibilities for each multilayer • least squares straight line fit obtained for each possibility • the fit with the smallest rms residual is kept • Global 8-tube fit • use left/right information from multilayer fits • least squares 8-tube fit • Global 6-tube fit • reject two most poorly fit tubes from 8-tube fit (eliminates some delta rays, multiple scatters, small impact parameter fluctuations) • least squares fit with remaining 6 tubes

  11. rms multiple scattering angle = 3.5 mrad mu070201a_f; theta < 100 mrad

  12. multiple scattering angle larger near beams mu070201a_f; ML fit rms < 80 microns; theta < 100 mrad

  13. FWHM*1.22/2.35 = 67 microns, MS cut (4 mrad) mu062901a_f; no scintillator cuts Residuals (mm)

  14. FWHM*1.22/2.35 = 74 microns, no MS cut mu062901a_f; no scintillator cuts; 97.5% of events Residuals (mm)

  15. Resolution Study • Use improved time-to-space function: • add correction for large impact parameter • add corrections for layer-layer variation • Select layer not used for track fit • Best of 128 possibilities for 7 other layers • Reject worst tube • Best of 64 possibilities for 6 layers • Compare fit position with excluded layer’s impact parameter

  16. Residuals (mm) for layer 3 - 5% delta rays mu070201a_f Impact parameter (mm)

  17. Residuals (mm) for layer 3 (res study) mu070201a_f Impact parameter (mm)

  18. Residuals for layer 3: FWHM/2.35 = 85 microns mu070201a_aj; m6:-.01-.01; chi6<60mic; imp:6.5-9.5mm Residual (mm)

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