Frank Geurts Rice Univ.

 Introducing ◦ barrel TOF and upVPD in Run 9  TOF software ◦ past, present, and future  Calibrations ◦ start, stop, and status MIT -- July 7, STAR Analysis Meeting

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. MIT -- July 7, STAR Analysis Meeting

EAST WEST TPC support arms Run-8 trays MIT -- July 7, STAR Analysis Meeting

 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 MIT -- July 7, STAR Analysis Meeting

 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 MIT -- July 7, STAR Analysis Meeting

 New offline DAQ reader based on RTSReader ◦ TOF data format specs v2.4 ★ ◦ implemented Run 8 MIT -- July 7, 2009 STAR Analysis Meeting7 StBTofHitMaker DAQ TOF Branch StBTofCollection: StBTofHeader StBTofRawHit StBTofHit StBTofCollection: StBTofHeader StBTofRawHit StBTofHit ◦ 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 ★ ) Jing Liu Xin Dong

 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 MIT -- July 7, 2009 STAR Analysis Meeting8 Offline DAQ Fast Offline Reconstruction EventQAMaker histograms QA by shift crew

MIT -- July 7, 2009 STAR Analysis Meeting9 STAR/TO F DAQ GSTAR geant hits GSTAR geant hits geometry (btofgeo) TOF Offline DAQ reader StBTofHitMaker TOF Offline DAQ reader StBTofHitMaker TOF Simulation Maker TOF Mixer Maker StBTofMatchMaker StBTofCalibMaker StEvent StBTofCollection StBTofRawHit StBtofHeader StBTofRawHit StBtofHeader StBTofHit StTrack StBTofPidTraits StMuBTofUtil StMuDstMaker StMuBTofUtil StMuDstMaker MuDst TOF StMcEvent StMcBTofHit BTofRawHit BTofHit BTofHeader BTofRawHit BTofHit BTofHeader association DB Tables StBTofUtil StBTofPool DB Tables StBTofUtil StBTofPool

MIT -- July 7, 2009 STAR Analysis Meeting10 StEvent StBTofCollection StBTofHit Track Nodes (global) StBTofPidTraits Projected TOF Hits Fired TOF Hits Init Matched TOF Hits Singly-Tracked Matched Hits Final Matched TOF Hits Track projection on TOF Matching of hits within one pad distance Associate one TOF hit with multiple tracks One track with multiple TOF hits TOF Cell Index Timing Projected position Associated Track … and remove

btofgeo.g and vpddgeo.g provide various TOF/VPD geometries: ◦ btofgeo.g -- btofConfigure ◦ vpddgeo.g -- vpddConfigure MIT -- July 7, 2009 STAR Analysis Meeting11 1Full CTBRun 1 2Full TOFp-- 325% TOFp +75% CTB-- 4TOFp +CTBRun 2 5TOFp+TOFr+CTBRun 3 6Full MRPC-TOFRun 9++ 7TOFp+TOFr’+CTBRun 4 8TOFr5+CTBRun 5 9-Run 6 10-Run TOFr8+CTBRun 8 1-6pVPDRun 2-5 7upVPDRun 6++

MIT -- July 7, 2009 STAR Analysis Meeting12 StBTofHitMaker DB Tables StBTofUtil DB Tables StBTofUtil StBTofCalibMaker StBTofMatchMaker StMuDstMaker/StMuBTOFUtil STBTofNtupleMaker Trees for Calibration

 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. Z local ) ◦ tray alignment calibration MIT -- July 7, 2009 STAR Analysis Meeting13

 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 April 26, 2009 Hanghzou Workshop on STAR TOF14 RMS RMS σ = ≈ 18ps INL applied no INL applied HPTDC integral non-linearity (INL): periodicity 1024 bins (25ns) calibration data collected on testbench expect no change, but will monitor Jing Liu

 HPTDC timing information is based on a free running clock ◦ determine optimal window for trigger timing ◦ timing affected by e.g. firmware changes MIT -- July 7, 2009 STAR Analysis Meeting15 Xiaoping Zhang Yi Zhou Final trigger timing window checked for Run 9 (500GeV) based on Fast-Offline data one parameter per tray, ready for database Applied by StBTofHitMaker

 Preliminary Calibration of Run 9 p+p 500 GeV ◦ based on Fast-Offline production, ~3M events MIT -- July 7, 2009 STAR Analysis Meeting16 Zebo Tang Xiaoping Zhang  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

Alternative approach in upVPD calibration  less sensitive to “outliers”, e.g. potentially resulting from additional vertices. MIT -- July 7, 2009 STAR Analysis Meeting17 Bill Llope Promising first results: Resolution per channel ~140ps  upVPD start resolution < 100ps (for 1.AND.1)

 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 TOF measured - TOF expected to 0 ◦ determined channel by channel, i.e. per MRPC cell ◦ Parameters done for 500GeV ◦ Ready for database ◦ Applied in StBTofCalibMaker MIT -- July 7, 2009 STAR Analysis Meeting18 Momentum p (GeV/c) dE/dx (KeV/cm) Tray 118 – Module 0 Zebo Tang

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 MIT -- July 7, 2009 STAR Analysis Meeting19 Run-8 [pp 200GeV] Run-9 [500GeV] 3M events

MIT -- July 7, 2009 STAR Analysis Meeting20 T-Z loc correlation in Run 5 Ming Shao  Local Z-hit position correction ◦ Expect a Z hit 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 Run 9 Run 8

 procedures involve several iterations ◦ e.g. using a slew-corrected timing to improve T ref or T0 timings  once a large statistical sample is available determine the tray alignment calibration MIT -- July 7, 2009 STAR Analysis Meeting21 start-side calibrationstop-side calibration

MIT -- July 7, 2009 STAR Analysis Meeting22 ToT fit failures σ ≈115ps Zebo Tang

MIT -- July 7, 2009 STAR Analysis Meeting23 Operation condition Time Resolution (ps) Start timeOverallStop time Run III 200GeV d+Au GeV p+p Run IV 62GeV (Au+Au) GeV (Au+Au) FF/RFF 2786(74)82(70) HF 2082(74)80(71) Run V 200GeV Cu+Cu (ToT) GeV Cu+Cu (ToT) Run VIII 200 GeV d+Au(ToT) NA 200 GeV p+p(ToT) Run IX 500 GeV p+p (preliminary) GeV p+p ---

 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) MIT -- July 7, 2009 STAR Analysis Meeting24