1. Calibration of DT-MTCC data
S.Bolognesi and G.Cerminara for the Torino group (N.Amapane, R.Bellan, C.Mariotti, G.Mila)
DT Cosmic Analysis - CERN 26/09/2006

2. Outlook RUN 669 (local, B off), 2602 (global B=3.8 T)
only events triggered by DTs
vdrift calibration (first time on MTCC!!)
vdrift = Lsemicell / tmeantime
reconstruction efficiency
segment quality
hit resolution
vdrift for B on (3.8 T) versus B off
ttrig calibration:
ttrig = tflex – k×s(ttrig)
is k factor stable for different SL?
ttrig and s(ttrig) for B on (3.8 T)
S. Bolognesi and G. Cerminara (TORINO) 1
DT Cosmic Analysis - CERN 26/09/2006

3. Noise and ttrig calibr.
Map of noisy channels using the standard test: look at occupancy before the time boxes
(DQM/DTMonitorClient)
noisy channels not used in ttrig and vdrift calibration
Reading t0 from map and calibration of tTrig from fit of TB rising edge:
tdrift = tmeasured – t0 – tTrig
correction for propagation along the wire off because the effect is compensated by the BX assignment (see Mary Cruz DT Meeting 08/29/06)
(CalibMuon/DTCalibration)
S. Bolognesi and G. Cerminara (TORINO) 2
DT Cosmic Analysis - CERN 26/09/2006

4. vdrift calibration
CalibMuon/DTCalibration package now includes also code (written by M. Giunta) to calibrate vdrift for each SL
meantimer calculation: different formulas for different track pattern
(see M.Giunta CMSWeek 08/06/04)
meantimer histos fitted with an automatic algorithm
drift velocity and hit resolution written in DB for each SL
a new DTRecHit reconstruction algo which read vdrift from DB released
RecoLocalMuon/DTRecHit/DTLinearDriftFromDBAlgo
S. Bolognesi and G. Cerminara (TORINO) 3
DT Cosmic Analysis - CERN 26/09/2006

5. Residuals move to 0 the mean of residual on the distance from wire:
| recHit position | - | segm. position |
Distribution of the means for each SL
before calibration
after calibration
Distribution of the sigmas for each SL
incertezza sui cosmici
mean 480mm
Because of the BX assignment we get big sigma of residuals for cosmic data:
mean 470 mm
sigma ~ √ mm ~ 450 mm
cell resolution ~ 200 mm
BX assignement
(25 ns/√12)×54 mm/ns ~ 400 mm
S. Bolognesi and G. Cerminara (TORINO) 4

6. Efficiency and c2
increase the efficiency of the segment reconstruction:
improve the chi2 of the segments:
c2 reduced mean on all the chambers
Impact angle (W1 St2 Sec10)
before calibration
3.0
after calibration
2.5
c2 reduced (W1 St1 Sec10)
Summing on all the chambers we get
4D segments / event
before calibration
1.7
after calibration
1.8
S. Bolognesi and G. Cerminara (TORINO) 5
DT Cosmic Analysis - CERN 26/09/2006

7. Number of hits number of hits for each segment increases
# of hits for segment (W1 St2 Sec10)
# of hits for segment (W1 St4 Sec14)
before calibration
8 hits
after calibration
12 hits
After the calibration:
better knowledge of vdrift for each SL
good estimation of the hit resolution for each SL
S. Bolognesi and G. Cerminara (TORINO) 6
DT Cosmic Analysis - CERN 26/09/2006

8. vdrift with B on ~2% B off (local run) B = 3.8 T (global run)
MB1
MB2
MB3
MB4 W2 W1 W2 W1 W2 W1 W2 W1 W1 W2 14 14 10 10 11 10 10 11 10 10 11 10 10 11
B off (local run)
B = 3.8 T (global run)
~2%
vdrift for each SL
MB1
MB2
MB3
MB4 W1 W2 W1 W2 W1 W2 W1 W2 W1 W2 10 10 11 10 10 11 10 10 11 10 10 11 14 14
MB1 W2 effetto maggiore come atteso
vdrift(Boff) - vdrift(Bon)
vdrift(Boff)
for each SL
SL theta
SL phi 7
CERN 26/09/2006

9. Hit resolution hit resolution distribution for each SL
hit resolution = vdrift × smeantimer
hit resolution distribution for each SL
MB1
MB2
MB3
MB4
mean 560mm
mean 600mm W1 W2 W1 W2 W1 W2 W1 W2 W1 W2 10 10 11 10 10 11 10 10 11 10 10 11 14 14
deviation from linearity
B off (local run)
CMS NOTE 2005/018
B = 3.8 T (global run)
With B on the resolution become worse because of deviations from linearity
S. Bolognesi and G. Cerminara (TORINO) 8

10. ttrig calibration: k factor
k factor for each superlayer choosen by minimizing the residuals (after vdrift calibration by SL)
ttrig = tflex – k×s(ttrig)
see S.B. Muon Software Session 02/09/06
Distribution of k factor
Distribution of sttrig
Distribution of k × sttrig
mean 7.3 ns
mean -7.3 ns
mean /- 0.01
RMS 0.88 ns
std. dev /- 0.01
RMS 0.94 ns
RMS 0.093
RMS (k) × <sttrig> < RMS (k × sttrig)
i.e. the fluctuations of k factor are smaller than the k*sttrig fluctuations
The use of k factor is convenient:
local fluctuations absorbed by sttrig and vdrift
k factor quite constant on all the chambers and SLs
S. Bolognesi and G. Cerminara (TORINO) 9
DT Cosmic Analysis - CERN 26/09/2006

11. ttrig with B on tTrig B off (local run) B = 3.8 T (global run)
MB1
MB2
MB3
MB4 W1 W2 W1 W2 W1 W2 W1 W2 W1 W2
B off (local run)
B = 3.8 T (global run) 10 10 11 10 10 11 10 10 11 10 10 11 14 14
s(tTrig)
MB1
MB2
MB3
MB4
TOF effect (10 ns) W1 W2 W1 W2 W1 W2 W1 W2 W1 W2 10 10 11 10 10 11 10 10 11 10 10 11 14 14
sttrig distribution for each SL
mean -7.1 ns
mean -8.1 ns
s(tTrig) increases of about 1 ns with B on because of the field lines distortion
S. Bolognesi and G. Cerminara (TORINO) 10

12. Conclusions Code to calibrate vdrift for each SL released
Preliminary test of vdrift calibration on cosmic data:
vdrift
better knowledge of
for each SLs
hit resolution
enhance of the reconstruction efficiency
improvement of the segment quality
B on VS B off comparison for vdrift and hit resolution:
right order of magnitude and reasonable behaviour but further studies still to be done
check of the k factor recipe after the vdrift calibration
check of the ttrig calibration with B on VS B off
S. Bolognesi and G. Cerminara (TORINO) 11
DT Cosmic Analysis - CERN 26/09/2006