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TOF Offline Report

TOF Offline Report. Frank Geurts Rice Univ. Outline. Introducing b arrel TOF and upVPD in Run 9 TOF software past, present, and future Calibrations start, stop, and status. TOF in Run9. Based on Multi-gap Resistive Plate Chambers (MRPC) v arious prototypes since Run 3.

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TOF Offline Report

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  1. TOF Offline Report Frank Geurts Rice Univ.

  2. Outline • Introducing • barrel TOF and upVPD in Run 9 • TOF software • past, present, and future • Calibrations • start, stop, and status STAR Analysis Meeting

  3. TOF in Run9 Based on Multi-gap Resistive Plate Chambers (MRPC) • various prototypes since Run 3. • timing electronics based on CERN’s HPTDC chip Significant increase in scale: • Run 8: 5 trays (4%) • Run 9: 86 out of 120 trays (72%) • Run 10: 120 trays (100%) Run 9 experience: • stable running, TOF participated in nearly all runs; • 10 dead channels out of 16,500; • average noise rate per channel is less than 10 Hz. STAR Analysis Meeting

  4. Run 9 TOF trays WEST EAST TPC support arms Run-8 trays STAR Analysis Meeting

  5. Start Side: the upVPD • upVPD replaced pVPD (Run8): • both based on scintillator and fast PMTs • uses similar timing electronics as TOF • upgrade involves increase in #channels from 6 to 38 channels (east + west) • STAR |Z|=570cm and 4.24 < |η| < 5.1 collision point STAR Analysis Meeting

  6. TOF Offline Software • Various prototype TOF trays resulted in an equally varied set of Makers: • StTof*, StTofp*, StTofr*, … (St_ctf_*) • StEvent TOF data model • includes legacy components • considerable overlap between classes • Significant maintenance burden to both TOF group and STAR • TOF Software Review (Nov.08) recommendation • freeze old versions • design new StEvent data model and clean reconstruction code accordingly • As of Run 9 production of TOF data only through StBTof* Makers and StBTof* classes in StBTofCollection • a lot of work done by Xin Dong STAR Analysis Meeting

  7. Offline DAQ Reader Jing Liu Xin Dong • New offline DAQ reader based on RTSReader • TOF data format specs v2.4★ • implemented Run 8 DAQ TOF Branch StBTofHitMaker • fiber data status and trigger time are stored in StBTofHeader • leading-edge and trailing-edge values are stored in StBTofRawHit • INL-corrected LE and TE values stored in StBTofHit • StBTofCollection: • StBTofHeader • StBTofRawHit • StBTofHit ★) http://www.star.bnl.gov/public/tof/electronics/TOF_Fiber_Data_Format_v2_4.pdf STAR Analysis Meeting

  8. Fast Offline QA Offline DAQ • event-wise hit distributions • matched hit distributions • channel-by-channel timing distributions • requires fast-offline calibration by experts • Vz from upVPD, TOF PID • Implemented in StEventQAMaker • During Run 8 and Run 9 QA by TOF experts • MatchMaker will soon be included in Fast Offline Fast Offline Reconstruction EventQAMaker histograms QA by shift crew STAR Analysis Meeting

  9. STAR TOF Offline Analysis Layout geometry (btofgeo) GSTAR geant hits STAR/TOF DAQ DB Tables StBTofUtil StBTofPool TOF Offline DAQ reader StBTofHitMaker TOF Simulation Maker TOF Mixer Maker StBTofCollection StEvent StMcEvent StBTofRawHit StBtofHeader association StBTofHit StMcBTofHit StBTofMatchMaker StBTofCalibMaker MuDst TOF BTofRawHit BTofHit BTofHeader StTrack StMuBTofUtil StMuDstMaker StBTofPidTraits STAR Analysis Meeting

  10. Matching Algorithm StBTofCollection StEvent Track Nodes (global) StBTofHit StBTofPidTraits Track projection on TOF Fired TOF Hits Projected TOF Hits Matching of hits within one pad distance • TOF Cell Index • Timing • Projected position • Associated Track Init Matched TOF Hits Associate one TOF hit with multiple tracks … and remove One track with multiple TOF hits Singly-Tracked Matched Hits Final Matched TOF Hits STAR Analysis Meeting

  11. TOF Geometry Defintions btofgeo.g and vpddgeo.g provide various TOF/VPD geometries: • btofgeo.g -- btofConfigure • vpddgeo.g -- vpddConfigure STAR Analysis Meeting

  12. Physics Production Chain StBTofHitMaker StBTofMatchMaker DB Tables StBTofUtil StBTofCalibMaker STBTofNtupleMaker StMuDstMaker/StMuBTOFUtil Trees for Calibration STAR Analysis Meeting

  13. TOF Calibrations • Integral Non-Linearity (INL) • Trigger timing window • Start-side calibration upVPD • signal slewing, T vs. Time-over-Threshold (TOT) • Stop-side calibration Barrel TOF • TOF T0 • signal slewing (T vs. TOT) • MRPC cell signal propagation (T vs. Zlocal) • tray alignment calibration STAR Analysis Meeting

  14. Integral Non-Linearity Calibration Jing Liu • HPTDC integral non-linearity (INL): • periodicity 1024 bins (25ns) • calibration data collected on testbench • expect no change, but will monitor • INL correction determined for all TOF HPTDC channels • Full TOF Barrel: 120x192 = 23k TDC channels • 1024 bins/channel at 2byte precision • In Offline Database • Applied by StBTofHitMaker RMS 3.993 RMS 0.7789 σ= 0.7659 ≈ 18ps no INL applied INL applied Hanghzou Workshop on STAR TOF

  15. Trigger Timing Window Xiaoping Zhang Yi Zhou • HPTDC timing information is based on a free running clock • determine optimal window for trigger timing • timing affected by e.g. firmware changes • Final trigger timing window checked for Run 9 (500GeV) • based on Fast-Offline data • one parameter per tray, • ready for database • Applied by StBTofHitMaker STAR Analysis Meeting

  16. upVPD Calibration Zebo Tang Xiaoping Zhang • Preliminary Calibration of Run 9 p+p 500 GeV • based on Fast-Offline production, ~3M events • Separate East & West Calibration • Iterative process • Low multiplicity in upVPD is an issue • not all events will have a start-time • Calibration constants ready for database (500GeV) • Applied by StBTofCalibMaker STAR Analysis Meeting

  17. upVPD Calibration (cont’d) Bill Llope Alternative approach in upVPD calibration • less sensitive to “outliers”, e.g. potentially resulting from additional vertices. Promising first results: Resolution per channel ~140ps upVPD start resolution < 100ps (for 1.AND.1) STAR Analysis Meeting

  18. Barrel TOF Calibration Zebo Tang • Use a clean π sample, either from TPC dE/dx (and momentum cuts) or a pre-calibrated TOF in the next iterations • T0 Calibration: • compensate for differences in cable lengths and signal transition times. • shifts the mean of TOFmeasured-TOFexpected to 0 • determined channel by channel, i.e. per MRPC cell • Parameters done for 500GeV • Ready for database • Applied in StBTofCalibMaker dE/dx (KeV/cm) Momentum p (GeV/c) Tray 118 – Module 0 STAR Analysis Meeting

  19. Barrel TOF Calibration (cont’d) Slewing Correction • compensates for correlation between signal timing and signal height. • time-over-threshold is proportional to signal height; based on a trailing edge timing measurement in addition to the leading edge • use spline fits, and store its shape, i.e. bin values • pp-500GeV: difficult to get enough statistics • corrections were performed per TDIG board (4 MRPCs, 24 channels) • Preliminary set ready for database, applied by StBTofCalibMaker Run-8 [pp 200GeV] Run-9 [500GeV] 3M events STAR Analysis Meeting

  20. Barrel TOF Calibration (cont’d) • Local Z-hit position correction • Expect a Zhit dependence as signal propagation on the pick-up pads can be 40-50ps/cm • No strong dependence observed in Run 8 and 9; not yet understood. • Corrections are available for Run 9 p+p 500GeV • ready for database, applied by StBTofCalibMaker T-Zloc correlation in Run 5 Ming Shao Run 8 Run 9 STAR Analysis Meeting

  21. TOF Calibration Procedures • procedures involve several iterations • e.g. using a slew-corrected timing to improve Tref or T0 timings • once a large statistical sample is available determine the tray alignment calibration start-side calibration stop-side calibration STAR Analysis Meeting

  22. Preliminary Run 9 (500GeV) results Zebo Tang σ ≈115ps ToT fit failures STAR Analysis Meeting

  23. Calibration History STAR Analysis Meeting

  24. Summary • TOF stable operations during Run 9 • TOF offline software: major changes • shed legacy code and introducing new BTOF classes • production makers for are in place for calibration • TOF calibration: full-steam ahead • 500GeV: first preliminary calibration • 200GeV: will require a larger data sample, verify the effect of the different discriminator threshold settings, verify field polarity change • Still a lot of work ahead: • Continue to roll-out new TOF offline components (StBTofCalibMaker, StBTofSimMaker, embedding) • Optimize existing and develop new calibration procedures (e.g. start-less TOF for low energy runs) STAR Analysis Meeting

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