Frank L. H. WolfsDepartment of Physics and Astronomy, University of Rochester Status of the TOF February 22, 2001 Straight-line tracking What have we learned? Position calibration Curved tracking What have we learned? Questions raised Time calibration Status What remains to be done?

Frank L. H. WolfsDepartment of Physics and Astronomy, University of Rochester Straight-line tracking Use Inkyu Park’s code to create straight-line tracks. The number of hits on the TOF is about times the number of reconstructed tracks (vertex dependent). A clear correlation exists between the hits on the TOF and the straight-line tracks. |z| < 1 cm

Frank L. H. WolfsDepartment of Physics and Astronomy, University of Rochester Straight-line Tracking Create straight-line tracks: Use theta-track to extrapolate to TOF Use hits on last two planes to extrapolate to TOF Conclude that using the last two hits improves TOF - SPEC matching.

Frank L. H. WolfsDepartment of Physics and Astronomy, University of Rochester Impact of multiplicity on TOF tracking Use vertical position to improve Signal/Noise

Frank L. H. WolfsDepartment of Physics and Astronomy, University of Rochester Using straight-line tracks for vertical position calibration of the TOF The vertical position of the TOF scintillators can be determined using the vertical position information from the track. Due to vertical segmentation of last silicon planes, we need to use the azimuthal track angle. A clear correlation is observed between y(track) and y(TOF). Procedure works nicely for the central scintillators, but not for those near 32.5 and 90 degrees.

Frank L. H. WolfsDepartment of Physics and Astronomy, University of Rochester Curved Tracks and TOF Multiplicity Number of straight-line tracks in SPECN scales with TOF multiplicity. Number of curved tracks in SPECN peaks at 1, independent of TOF multiplicity. Only events with at least two tracks can be used for TOF-based particle identification.

Frank L. H. WolfsDepartment of Physics and Astronomy, University of Rochester Curved Tracking Use Gunther’s DSTs with curved tracks. Use last two hits in SPECN and do a linear extrapolation to the TOF. Expect a correlated angular shift as a function of momentum. Simulation for pions

Frank L. H. WolfsDepartment of Physics and Astronomy, University of Rochester B-, PID 9 Positive charges, bending backward Correlated Hits.

Frank L. H. WolfsDepartment of Physics and Astronomy, University of Rochester B-, PID 8 Negative charges, bending forward Correlated Hits.

Frank L. H. WolfsDepartment of Physics and Astronomy, University of Rochester B+, PID 9 Negative charges, bending backward Correlated Hits.

Frank L. H. WolfsDepartment of Physics and Astronomy, University of Rochester B+, PID 8 Positive charges, bending forward Correlated Hits.

Frank L. H. WolfsDepartment of Physics and Astronomy, University of Rochester TOF Timing Procedure: Calculate timing shift in TDC START due to vertex position (START delayed when vertex is not at 0 cm). Apply offset and slewing corrections. Find the fastest particle (note: not necessarily the earliest). Assume the fastest particle travels with v = c, and use this to determine t0. Correct all times for t0.

Frank L. H. WolfsDepartment of Physics and Astronomy, University of Rochester TOF Timing Optimizing TOF Resolution: Look at time difference between fastest and second fastest particle. Adjust slewing parameters to minimize the width of the time distribution: Threshold: determined for each channel using the timing efficiency Rise time: one common time for all channels (to be adjusted individually) Time resolution achieved so far is 140 ps (1  ). This corresponds to a resolution of 100 ps (1  ) per scintillator.

Frank L. H. WolfsDepartment of Physics and Astronomy, University of Rochester Summary and To-Do List Capability to match SPECN tracks and TOF hits has been developed for both field-on and field-off data. Straight-line tracks useful for vertical position calibration. Procedure to determine t0 has been developed (field off). TOF resolution of 140 ps (1  ) has been achieved. Finish vertical position calibration for scintillators located close to 32.5 degrees and 90 degrees. Optimize slewing corrections by using separate rise times for each PMT channel (various procedures are under consideration). Modify t0 determination for curved tracks. Use vertical position info to improve matching efficiency.