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TOF Offline ReportFrank Geurts
Rice Univ.
STAR Analysis Meeting 2
Introducing◦ barrel TOF and upVPD in Run 9
TOF software◦ past, present, and future
Calibrations◦ start, stop, and status
Outline
MIT -- July 7, 2009
STAR Analysis Meeting 3
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.
TOF in Run9
MIT -- July 7, 2009
STAR Analysis Meeting 4
Run 9 TOF trays
EAST
WEST
TPC support arms
Run-8 trays
MIT -- July 7, 2009
STAR Analysis Meeting 5
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
Start Side: the upVPD
collision point
MIT -- July 7, 2009
STAR Analysis Meeting 6
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
TOF Offline Software
MIT -- July 7, 2009
STAR Analysis Meeting 7
New offline DAQ reader based on RTSReader◦ TOF data format specs v2.4★
◦ implemented Run 8
MIT -- July 7, 2009
Offline DAQ Reader
StBTofHitMaker
DAQ TOF Branch
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
★) http://www.star.bnl.gov/public/tof/electronics/TOF_Fiber_Data_Format_v2_4.pdf
Jing LiuXin Dong
STAR Analysis Meeting 8
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
Fast Offline QAOffline DAQ
Fast Offline Reconstruction
EventQAMaker
histograms
QA by shift crew
STAR Analysis Meeting 9MIT -- July 7, 2009
STAR TOF Offline Analysis Layout
STAR/TOF DAQ
GSTARgeant hits
geometry (btofgeo)
TOF Offline DAQ readerStBTofHitMaker
TOF Simulation Maker
TOF Mixer Maker
StBTofMatchMaker
StBTofCalibMaker
StEvent
StB
TofC
olle
ctio
n StBTofRawHitStBtofHeader
StBTofHit
StTrackStBTofPidTraits
StMuBTofUtilStMuDstMaker
MuDst TOF
StMcEvent
StMcBTofHit
BTofRawHitBTofHit
BTofHeader
association
DB TablesStBTofUtilStBTofPool
STAR Analysis Meeting 10MIT -- July 7, 2009
Matching AlgorithmStEvent
StBTofCollection
StBTofHit
Track Nodes (global)
StBTofPidTraits
Projected TOF HitsFired 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 tracksOne track with multiple TOF
hits
•TOF Cell Index•Timing•Projected position•Associated Track
… and remove
STAR Analysis Meeting 11
btofgeo.g and vpddgeo.g provide various TOF/VPD geometries:◦ btofgeo.g -- btofConfigure
◦ vpddgeo.g -- vpddConfigure
MIT -- July 7, 2009
TOF Geometry Defintions
1 Full CTB Run 1
2 Full TOFp --
3 25% TOFp +75% CTB
--
4 TOFp +CTB Run 2
5 TOFp+TOFr+CTB Run 3
6 Full MRPC-TOF Run 9++
7 TOFp+TOFr’+CTB Run 4
8 TOFr5+CTB Run 5
9 - Run 6
10 - Run 7
11 5 TOFr8+CTB Run 8
1-6 pVPD Run 2-5
7 upVPD Run 6++
STAR Analysis Meeting 12MIT -- July 7, 2009
Physics Production Chain
StBTofHitMaker
DB TablesStBTofUtil
StBTofCalibMaker
StBTofMatchMaker
StMuDstMaker/StMuBTOFUtil
STBTofNtupleMaker
Trees for Calibration
STAR Analysis Meeting 13
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
MIT -- July 7, 2009
TOF Calibrations
Hanghzou Workshop on STAR TOF 14
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
Integral Non-Linearity Calibration
RMS 3.993
RMS 0.7789
σ = 0.7659 ≈ 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
STAR Analysis Meeting 15
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
Trigger Timing WindowXiaoping 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
STAR Analysis Meeting 16
Preliminary Calibration of Run 9 p+p 500 GeV◦ based on Fast-Offline production, ~3M events
MIT -- July 7, 2009
upVPD CalibrationZebo 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
STAR Analysis Meeting 17
Alternative approach in upVPD calibration less sensitive to “outliers”, e.g. potentially
resulting from additional vertices.
MIT -- July 7, 2009
upVPD Calibration (cont’d)Bill Llope
Promising first results:
Resolution per channel ~140ps upVPD start resolution < 100ps
(for 1.AND.1)
STAR Analysis Meeting 18
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
MIT -- July 7, 2009
Barrel TOF Calibration
Momentum p (GeV/c)dE/d
x (
KeV
/cm
)
Tray 118 – Module 0
Zebo Tang
STAR Analysis Meeting 19
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
Barrel TOF Calibration (cont’d)
Run-8[pp 200GeV]
Run-9 [500GeV]3M events
STAR Analysis Meeting 20MIT -- July 7, 2009
Barrel TOF Calibration (cont’d)
T-Zloc correlationin Run 5
Ming Shao
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 Run 9
Run 8
STAR Analysis Meeting 21
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 MIT -- July 7, 2009
TOF Calibration Procedures
start-side calibration stop-side calibration
STAR Analysis Meeting 22MIT -- July 7, 2009
Preliminary Run 9 (500GeV) results
ToT fitfailures
σ ≈115ps
Zebo Ta
ng
STAR Analysis Meeting 23MIT -- July 7, 2009
Calibration History
Operation conditionTime Resolution (ps)
Start time Overall Stop time
Run III200GeV d+Au 85 120 85
200GeV p+p 140 160 80
Run IV
62GeV (Au+Au) 55 105 89
200GeV (Au+Au)
FF/RFF 27 86(74) 82(70)HF 20 82(74) 80(71)
Run V200GeV Cu+Cu (ToT) 50 92 7562GeV Cu+Cu (ToT) 82 125 94
Run VIII200 GeV d+Au(ToT) NA NA NA200 GeV p+p(ToT) 83 112 75
Run IX500 GeV p+p (preliminary) 85 115 78
200 GeV p+p - - -
STAR Analysis Meeting 24
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
Summary