TOF Offline Report

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


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


Run 9 TOF trays

EAST

WEST

TPC support arms

Run-8 trays

MIT -- July 7, 2009


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


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


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


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


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


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++


Physics Production Chain

StBTofHitMaker

DB TablesStBTofUtil

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. 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


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


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


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)


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


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


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


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


Preliminary Run 9 (500GeV) results

ToT fitfailures

σ ≈115ps

Zebo Ta

ng


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 - - -


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

Documents

TOF Offline Report