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 Data taking on cosmic rays June - August 2001 Data analysis September - October 2001

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

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

Cosmic Ray Test Stand

Mod-0 on Test Stand

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

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

Exact tdc vs r for special cases TDC 403 r(mm) r(mm) TDC

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

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

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

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

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

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

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

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

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

mu070201a_aj; m6: ; chi6<60mic; imp: mm Residual (mm) Residuals for layer 3: FWHM/2.35 = 85 microns