The time-of-flight reconstruction & calibration Jiang lin li 2004.3.26
TOF reconstruction flowchart TOF counter raw data Associate hits in the TOF counters with tracks Calculate time-of-flight and error, velocity , Mass –squared, weight for various particle hypotheses etc Put these quantities in the track list
Filling the Raw data Array For barrel counters with both ends TDC and ADC
Matching counters with tracks For each track, a search is made for an associated counter. There are three possibilities: 1: a MDC track projects into the time-of-flight counter 2: a photon have associated hits in the time-of-flight 3: a counter have a hit without being associated with any track in the MDC or shower counter
Time correction
Pulse height corrections
Charge sharing algorithm Two tracks extrapolate to a single barrel counter
Calculation of the time of flight two end PMT was fired : one end PMT was fired:
time-of-flight errors calculation
Calculation of the ß and mass-squared From the time T and the path length L determined by the drift chamber ,ß is calculated . From ß and P, Mass-squared of track is calculated.
Particle hypothesis probability
Put above quantity into the track list
Some time correction formula:
Time correction in general: 1 Time offset run by run 2 Time-walk correction F(Q) 3 The effective velocity in the scintillator correction F(z) 4 Cable delay and the transit time of PMT ……