1. Scintillation Detectors in High Energy Physics
Shashikant R. Dugad
Tata Institute of Fundamental Research
Ref. Summer Student Lecture Series 2001, by C. Joram at CERN

2. Scintillators
Fast Light Emitting Medium on passage of charged particle
Inorganic Scintillators (Slow Response, high light o/p)
Organics Scintillators (Fast Response, low light o/p)
Analog Signal

3. Inorganic Scintillators
Temp. dependent light o/p
Inorganic Scintillators are costly and mostly used in Nuclear Physics Experiments
Response time varies from ~ nsec
PbWO4 is used to make calorimeter to measure energy of e+e- γ

4. Organic Scintillators
Monocrystals: napthalene, anthracene, p-terephenyle
Liquid and plastic scintillators: Composed of solvent + dopent (popup) used as wavelength shifter (from UV to visible)
Organic scintillators are cheap and have fast response (~ few nsec)
Made and used in Ooty-GRAPES3 experiment

5. Properties of Organic Scintillators
Used in large area detection requirement: Sampling EM component in air showers, Hadron Calorimeter, Muon time tagging in accelerator experiment

6. Scintillation Light Transport
Scintillation light comes out from all surfaces
…..Needs to be navigated to photodetector
GRAPES3 Scintillator

7. Light transport in fibers

8. Scintillating fiber tracker
UA2 experiment

9. Detection of scintillation photon (photo detector)
Photo electron
Photo sensitive material
(photocathod)
Epe = Eγ - W

11. Quantum Efficiency of Photo cathode

12. Estimation of Signal Strength
Charged particle passes through 1cm thick scintillator
Total Energy loss by ionisation ~ 2MeV
Number of scintillation photons produced ~ (λ~ nm)
Number of photons captured by WLS fiber ~ 200
Number of photo electrons produced at photo cathode ~ 20
Total number of electrons at PMT last dynode (i/p of preamp) ~ 108
Typical S/B Ratio ~ 10

13. PMT Signal Resolution
GRAPES3 PMT

14. Photo Detectors

15. Hybrid Photo Diode
HPDs are used in CMS experiment for HCAL detector

16. Si-Photo Multiplier

17. Applications μ Muon Bunch Crossing Tagging in D0 experiment p p
Scintillator
Tracker (Gas Detector) p p
Tracker (Gas Detector)
Scintillator
Muon Bunch Crossing Tagging in D0 experiment

18. Shashi Dugad, WAPP, Ooty, 18 Dec 2012
SiPM Response to Muons
SiPM Make
SiPM Size
(mm)
Pixel
Size (μ)
# of pixels
a) CPTA1
b) CPTA2
c) IRST(FBK)
d) Hamamatsu
2.1 x 2.1
2.8 dia
3.0 x 3.0 50
1800
2400
3600
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

19. Silicon Photomultiplier
Characterization
I-V characteristics
Single pixel calibration
Linearity, MIP sensitivity
Micron resolution optical scanner for studying pixel-to-pixel response
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

20. Shashi Dugad, WAPP, Ooty, 18 Dec 2012
IV Characteristic of SiPM
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

21. Shashi Dugad, WAPP, Ooty, 18 Dec 2012
LED Calibration Setup
Signal Generator
LED
SiPM
Signal
Trigger
qADC
VME Crate
Computer
Data
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

22. Shashi Dugad, WAPP, Ooty, 18 Dec 2012
Noise Rate and LED Response
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

23. Shashi Dugad, WAPP, Ooty, 18 Dec 2012
LED Test Results for Pixel 01
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

24. Shashi Dugad, WAPP, Ooty, 18 Dec 2012
MIPs with SiPM at Ooty
WLS Fibers laid on scintillator (25 x 25 cm2) terminated onto
Hamamatsu SiPM
MIP signal with 44 p.e. at peak is seen (high Q.E.)
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

25. Temperature Dependence of the Gain
Cosmic muon data taken over period of 2 days Temp. variation
of 4OC
Data binned in temp. slice of 0.25OC
MIP peak obtained for each set plotted as function of temp.
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

26. Shashi Dugad, WAPP, Ooty, 18 Dec 2012
CMS Detector HF HO HB HE
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

27. Shashi Dugad, WAPP, Ooty, 18 Dec 2012
TB2009: HB Setup
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

28. Shashi Dugad, WAPP, Ooty, 18 Dec 2012
Application of SiPM in CMS Detector
Fibers from Scintillator tiles
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

29. Shashi Dugad, WAPP, Ooty, 18 Dec 2012
HPD and SiPM Response
Muons with HPD
50 GeV Discharge in HPD
S/B~2
SiPM in Magnetic Field
Muons with SiPM
S/B~15
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

30. Shashi Dugad, WAPP, Ooty, 18 Dec 2012
SiPM Control Board
160 boards fabricated indigenously by GRAPES3, Ooty
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

31. Shashi Dugad, WAPP, Ooty, 18 Dec 2012
Data Set
Muon Beam at 150 GeV
Beam Direction(η, φ)
Pion-Beam Energy
7,3
300 GeV
225 GeV
150 GeV
100 GeV
50 GeV
30 GeV
7,4
8,3
8,4
150K events (ped+pion) events at each energy and position
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

32. HO Calibration with 150 GeV Muons
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

33. Analysis procedure …contd
Subtract pedestal from signal and normalise by with muon calibration constant
Number of MIPS nMIPs
Take nMIPs(i) sum for all 9 towers at each depth of HB and HO
Pion Energy = Constant*[A*nMIPs(1) + B*nMIPs(2) + C*nMIPs(3) + D*nMIPs(4) + E*nMIPsHO]
Natural Relative Weights: A=0 B=C=1 D=6 E ~ 3.1
Estimation of Weights
Pion data at 300 GeV at eta=7 and phi=3 used to estimate weights for each depth of HB and one layer of HO
Vary one of the weights by fixing other weights to natural values and obtain RMS/Mean as function of that weight
EGeV=0.247*(1.05*nMIPs(2) *nMIPs(3) *nMIPs(4) *nMIPsHO)
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

34. Zecotek response to 300 GeV Pions in HO at Eta=7 Phi=4
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

35. Zecotek/Hamamatsu response to 300 GeV Pions in HO at Eta=7
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

36. Shashi Dugad, WAPP, Ooty, 18 Dec 2012
Relative Weight Factor for HB/HO
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

37. Shashi Dugad, WAPP, Ooty, 18 Dec 2012
Resolution of HB+HO O
Shashi Dugad, WAPP, Ooty, 18 Dec 2012

38. Shashi Dugad, WAPP, Ooty, 18 Dec 2012
Summary
SiPM is photo-readout element of 21st century
Being used in large high energy physics experiments
GRAPES-3 collaboration have completed HO-upgrade (~2800 channels) for CMS experiment
Potential candidate in medical industry for imaging
Several groups within country are working on this device
Shashi Dugad, WAPP, Ooty, 18 Dec 2012