Comparison of algorithms for hit reconstruction in the DTs: Test of calibration procedures for t trig and drift velocity on Test Beam data Test of calibration code and v drift parametrization on TB2004 data digi (time) recHit (distance)  constant drift velocity  parametrized drift velocity * S.Bolognesi, G.Cerminara Muon week (08 February 2006) * CMS IN 2005/037 J.Puerta-Pelayo, M.C.Fouz, P.Garcia-Abia

 TB2004 TB data run2551 Muon week (08 February 2006)  (deg) beam phi theta MB1 MB3 1 no vertex constraint  Preliminar cut: requested at least 12 hits for each segment we want to study the performances of the hit reconstruction algorithms independently from performances of the chambers and the track fitting algorithm S.Bolognesi, G.Cerminara x y z

Calibration  Residual on distance = |x measured (x RecHit )| – |x extrapolated (x extr )| In the residual distribution is impossible to disentangle the effects of miscalibration of t trig and v drift  Meantimers to calibrate v drift strongly depend on the t trig t trig effect Muon week (08 February 2006) 2S.Bolognesi, G.Cerminara

Constant v drift :  t trig,  (t trig ) calibration = k factor optimization (by SL):  v drift fit of the rising edge of the time boxes with the integral of a gaussian (by SL) t m = t 0 pulses + t.o.f. + t prop + t offset + t drift t trig = t flex – k×  (t trig ) x m -x extr x extr > 0 x extr < 0 1) residual distribution on position for different k factors 2) fit of (  1 -  2 )/2(  1 +  2 ) vs k (v drift = 54.3  m/ns) fit of the meantimer distributions (by SL) re-calibrate the k factor Muon week (08 February 2006) 3 11 22 S.Bolognesi, G.Cerminara calibration procedure

BEFORE CALIBRATION AFTER CALIBRATION  = 0° (SL1) Re-fitting the segment without the recHit itself  (residual) increases of about 100  m The calibration software in ORCA works for all the considered angles because it implements different meantimer formulas for different track patterns Muon week (08 February 2006) 4S.Bolognesi, G.Cerminara Constant v drift : calibration results (1)

 = -20° (SL1) AFTER CALIBRATION BEFORE CALIBRATION Constant v drift : calibration results (2) Muon week (08 February 2006) 5S.Bolognesi, G.Cerminara

Parametrized v drift : calibration  t trig and  (t trig ) calibrated with the same strategy  the parametrization of the v drift doesn’t provide any parameter for calibration Muon week (08 February 2006) 6S.Bolognesi, G.Cerminara t trig miscalibration effects shift on the mean (like for the constant v drift ) increase of the width (  ) because the non linearities are also shifted NOTE: the t trig for the parametrized v drift is different from the one for the constant v drift because the parametrization has its own intrinsic offset  = -20° (SL1)

Conclusions and plans on calibration  we have applied a preliminary calibration procedure on the TB data and we have obtained good results  all the code necessary for the calibration is already implemented in ORCA (Muon/MBCalibration * )  these algorithms will be ported in CMSSW as soon as all the segment reconstruction software will be in place Muon week (08 February 2006) 7S.Bolognesi, G.Cerminara * see G.Cerminara PRS/MU (10 Jan ’06)  t trig -k×sigma(t trig ) is the best recipe? k is not the same for different chambers/SL  we have to check the robustness of the calibration strategy we have used: start from a big miscalibration on v drift to verify the convergence of the procedure Conclusions ToDo

 constant drift velocity  parametrized drift velocity Constant v drift VS parametrized v drift There are two hit reconstruction algorithms available in ORCA Parametrization based on cell simulation obtained with GARFIELD x = x(t, , B wire, B norm ) test these two algorithms  on real data  for different angles GOAL OF THIS STUDY: Muon week (08 February 2006) 8S.Bolognesi, G.Cerminara

Residual on distance from wire Muon week (08 February 2006) PARAMETRIZED v drift CONSTANT v drift 9 with the constant drift velocity we have a worse resolution and bigger tails due to non linearity effects Fit with the sum of two gaussians S.Bolognesi, G.Cerminara AFTER CALIBRATION  = -10° (SL1) a central peak (  1  resolution) large gaussian for the tails

Residual on distance from wire VS distance non linearity effects cause the larger tails in the residual distribution non linearity effects reduced to 100  m CONSTANT v drift (200  m very close to the anode wire) PARAMETRIZED v drift AFTER CALIBRATION  = -10° (SL1) Muon week (08 February 2006) 10S.Bolognesi, G.Cerminara

Residuals VS  angle Muon week (08 February 2006) 11 ToDo  Introduce the possibility of calibrate parametrization on the data S.Bolognesi, G.Cerminara (at least the mean value of the drift velocity) We get the best results using the parametrized v drift but for a more precise comparison we need to develop a more sophisticated calibration strategy SL3