1. 10th particle physics conference
Upgrade of electronics and corresponding calibration procedure for STAR time-of-flight detector
Ming SHAO
USTC
2018/11/20
10th particle physics conference

2. STAR physics program and TOF upgrade
Near term
TOF
Long term
Thermometers: dilepton, photon
heavy quarkonium species.
jet fragments tagged by a hard direct photon, a heavy flavor
elliptic flow in U+U collisions.
LHC and GSI energies
fundamental QCD symmetries
v2 scaling for coalescence
jet quenching as parton energy loss
energy dependence testing model prediction
Heavy flavor yields and flow: color screening and partonic collectivity
forward jet correlation: CGC
ID-particle spectra
freeze-outs
hadronization
ID-particle correlations
In-medium jet
Fluctuations and correlations
Lepton program
In-medium vector meson
Heavy Flavor
Baseline detector for future upgrades
Identified hadron spectra
freeze-out dynamics
hadronization mechanism
Identified particle correlations
Chemical and kinetic properties of in-medium jet associated spectra
Fluctuations and correlations
Lepton program
In-medium vector meson properties
Heavy flavor
Baseline detector for future upgrades
Near/Long Term: STAR white paper, Nucl. Phys. A 757 (2005) 102
2018/11/20
10th particle physics conference

3. What can we get from TOF (I)
- Resonance decay
/p misidentified as K
Suppress background
Rare particle searching
Increase S/B, decrease data sample size
130GeV AuAu
2018/11/20
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4. 10th particle physics conference
What can we get from TOF (II)
- Open charm
- Fluctuation
<pT> fluctuation
3 signal (D0+D0bar)
2018/11/20
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5. 10th particle physics conference
What can we get from TOF (III)
- RHIC energy scan
K+/+
v1, v2
v2 fluctuation, <pT> fluctuation …
All benefit from a nearly complete direct PID
2018/11/20
10th particle physics conference

6. MRPC TOF (TOFr) – stop time measurement pVPD - start time measurement
Detectors -PID
TPC- tracking
Particle momentum;
dE/dx
~8% resolution
/K separation to ~0.6GeV/c
K/p separation to ~1.0GeV/c
MRPC TOF (TOFr) – stop time measurement
pVPD - start time measurement
Aim at 100ps time resolution TOF system
/K separation to ~1.6GeV/c & K/p separation to ~3.0GeV/c
2018/11/20
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7. 10th particle physics conference
TOF system
pVPD consists of plastic scintillator + fast PMT, 5.4m from TPC geometry center along the beam line
3 channels each side (run5 and before) upgrade to 19 channels each side (after run5)
Full barrel TOF consists of 120 trays, 32 MRPC modules per tray, 6 channels (strips) per module
Only one tray in run5
2018/11/20
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8. 10th particle physics conference
TOF Trays along years
run5
run4
run3
Better mechanical design
Simpler fabrication
improved tolerance
Optimized electronics
2018/11/20
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9. 10th particle physics conference
TOF DAQ
Before run5
Run5 and later
Peripheral Component Interconnec/interfacet，周边元件扩展接口
Source Interface Unit
Read Out Receive Card
NIM local trigger based on pVPD signals
CAMAC digitalization w.r.t local trigger
I/O via PCI board and to STAR over network
Slewing via ADC
No local trigger
HPTDC digitalization w.r.t clock (time stamps)
I/O via SIU/RORC fiber directly to STAR
Slewing via Time-Over-Threshold (TOT)
2018/11/20
10th particle physics conference

10. Tray Level Electronics
2 THUB per side, 4 total
1 TCPU per tray/pVPD, 122 total
1 TPMT/TDIS per pVPD, 2 total
8 TINO/TDIG per tray, 960 total
24 chn. per TINO/TDIG, total
2018/11/20
10th particle physics conference

11. HPTDC Time Measurement
HPTDC is fed by a 40 MHz clock giving us a basic 25 ns period (coarse count).
A PLL (Phase Locked Loop)
device inside the chip does clock multiplication by a factor 8 (3 bits) to 320 MHz (3.125 ns period) .
A DLL (Delay Locked Loop)
done by 32 cells fed by the PLL clock acts as a 5 bit hit register for each PLL clock (98 ps width LSB = ns/32).
4 R-C delay lines
divide each DLL bin in 4 parts (R-C interpolation)
Coarse time (bin width 25 ns, 11 bits)
PLL bits
(bin width ns)
DLL bits
(bin width 98 ps)
MSB
LSB
R-C bits
(bin width 24.4 ps)
2018/11/20
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12. 10th particle physics conference
Run5 Setup
2018/11/20
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13. 10th particle physics conference
Run5 Setup
2018/11/20
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14. 10th particle physics conference
Run5 Setup
2018/11/20
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15. 10th particle physics conference
Run5 Setup
2018/11/20
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16. 10th particle physics conference
Run5 Setup
2018/11/20
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17. TOF Calibration – run5 (and later on)
Data sample (after TOF matching):
~8.4M from CuCu 62.4GeV, ~4.3M from CuCu 200GeV
Leading-edge discrimination : timing signal
Trailing-edge discrimination: signal width (TOT)
time
Amp.
T1l T2l T2t T1t
Thre.
Time stamp
MRPC strip
Readout
2018/11/20
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18. Calibration procedure
Choose  sample by limiting dE/dx and momentum range (or pre- calibrated TOF)
Use spline fit (3rd polynomials TSplineFit based on ROOT developed by François-Xavier Gentit)
pVPD calibration (start time)
TOFr Cell_by_cell TOT and Z position calibration, using charged pion sample.
Iteration several times (if needed)
2018/11/20
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19. 10th particle physics conference
pVPD TOT Correction
2018/11/20
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20. TOT slewing pattern (I)
Module:
1, 2, 3, 4
tof - texpect
TOT (ns)
2018/11/20
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21. TOT slewing pattern (II)
Module:
17, 18, 19, 20, 25, 26, 27, 28
tof - texpect
TOT (ns)
2018/11/20
10th particle physics conference

22. TOT slewing pattern (III)
Module:
5, 6, 7, 8, 21, 22, 23, 24, 29, 30, 31, 32
tof - texpect
TOT (ns)
2018/11/20
10th particle physics conference

23. Hit position (Z) corrction
2018/11/20
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24. 10th particle physics conference
TOF Time Resolution
CuCu 62.4GeV
CuCu 200GeV
2018/11/20
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25. TOF Time Resolution Summary
Run3 to run5
Operation conditions
Time Resolution (ps)
pVPD
TOFr (overall)
TOFr (stop time)
Run3
200GeV d+Au
~85
~120
200GeV p+p
~140
~160
~80
Run4
62GeV (Au+Au)
~55
~105
~89
200GeV (Au+Au)
FF/RFF
~27
~86(74)
~82(70) HF
~20
~82(74)
~80(71)
Run5
200GeV Cu+Cu (TOT)
~ 50
~92
~75
62GeV Cu+Cu (TOT)
~ 82
~125
~94
2018/11/20
10th particle physics conference

26. Hadron/electron/muon PID capability
|1/β-1|<0.03
electrons
Hadron PID: (, K) ~1.6 GeV/c , p ~ 3 GeV/c.
STAR Collaboration, PLB 616 (2005) 8
Clean electron PID can be obtained up to PT< 3 GeV/c. 
This is used to measure the semileptonic decay of open charm.
STAR Collaboration, PRL94 (2005)
Significantly reduce the systematic uncertainty on the charm cross section measurement.
STAR Collaboration, PLB 639 (2006) 441
2018/11/20
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27. 10th particle physics conference
Physics from TOF (I)
Cronin effect
High pT /p
STAR Collaboration:
PLB 595 (2004) 143
PLB 616 (2005) 8
PLB 637 (2006) 161
PRL 97 (2006)
PLB 655 (2007) 104
2018/11/20
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28. 10th particle physics conference
Physics from TOF (II)
STAR Collaboration, PRL 94 (2005)
STAR Collaboration, PLB 639 (2006)
Open charm
2018/11/20
10th particle physics conference

29. 10th particle physics conference
Summary and outlook
New STAR-TOF electronics tested in recent physics runs. Technical details are verified, close to final design and waiting for production.
Calibration procedure re-newed according to electronics upgrade. Consistent performance , esp. time resolution of ~80ps, is obtained.
Rich physics from TOF, more in the future…
Coming soon
Half barrel TOF (60 trays) at run9
Full barrel TOF (120 trays) at run10
Fully commissioned at run11
2018/11/20
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30. 10th particle physics conference
Backup Slides
2018/11/20
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31. HPTDC Buffering & Readout
8 25ps or
32 100ps
Level-0 Trigger
Bunch
Crossing
Hit Buffer
Level-0
Buffering
2018/11/20
10th particle physics conference

32. Front-End Electronics “TINO”
ALICE NINO Chip
8 per tray
960 total
Parameter
Value
Peaking time
1ns
Signal Range
100fC – 2pC
Noise (with detector)
< 5000 e- rms
Front edge time jitter
<25ps rms
Power consumption
30 mW/ch
Discriminator threshold
10fC to 100fC
Differential Input impedance
40Ω< Zin < 75Ω
Output interface
LVDS
2018/11/20
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33. 10th particle physics conference
MRPC Digitizer “TDIG”
8 per tray
960 total
2018/11/20
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34. 10th particle physics conference
INL Correction
Sigma = 0.9 timebins = 22 ps
Implies single channel resolution of 16ps
2018/11/20
10th particle physics conference

35. Tray Controller “TCPU”
1 per tray
1 per Start Detector
122 total
2018/11/20
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36. DAQ/Trigger Interface “THUB”
2 per Detector side
4 total
2018/11/20
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37. 10th particle physics conference
PMT Input Board “TPMT”
1 per Start Detector
2 total
2018/11/20
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38. START Detector Digitizer “TDIS”
1 per Start Detector
2 total
2018/11/20
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39. ALICE DDL Link Front-end electronics Source DDL SIU Interface Unit
Optical Fibre
~200 meters
Detector
Data
Link
Destination
Interface
Unit
DDL DIU
Read
Out
Receiver
Card
RORC PC
Data Acquisition PC
2018/11/20
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40. 10th particle physics conference
Hadron PID
2018/11/20
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41. 10th particle physics conference
Electron PID
2018/11/20
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42. 10th particle physics conference
Muon PID
2018/11/20
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43. 10th particle physics conference
Run-VIII PID
1.2<p<1.4 GeV/c
2018/11/20
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44. Calibration Procedure – run4
Leading-edge trigger, signal charge (ADC) is measured for correction
time
Amp.
T1 T2
Thre. Q1 Q2
2018/11/20
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45. pVPD Calibration – start time
2018/11/20
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46. TOFr Calibration – MRPC TA & TZ
TA slewing correction
Hit position (TZ) correction
7th-order polynomial
2018/11/20
10th particle physics conference