1. Development of GEM DHCAL
Jae Yu
University of Texas at Arlington
May 25, 2009
Seoul National University
Introduction
Digital Hadron Calorimeter with GEM
Status of GEM DHCAL Development
High Density KPiX Analog Readout
GEM DHCAL Plans
Conclusions
May 25, 2009
GEM DHCAL Development; J. Yu

2. GEM Detector Development
High Energy Physics
Definition: A field of Physics pursues for fundamental constituents of matter and basic principles of interactions between them
Known interactions (forces):
Gravitational
Electro-Weak
Strong
Current theory: The Standard Model of Particle Physics
Unified Weak and Electromagnetic: SU(2)xU(1)
Strong Interaction: SU(3)
Currently:SU(3)xSU(2)xU(1)
Meaning: 8+4 mediators for forces
May 28, 2009
GEM Detector Development
J. Yu, UT Arlington

3. Particle Physics Model
High Energy Physics pursues for fundamental constituents of matter and the forces between them
So the secrete and its birth of universe
The Standard Model has been extremely successful
Three families of leptons and quarks together with 12 force mediators  Simple and elegant!!!
Discovered in
1995, 175mp
~0.1mp
Directly observed in 2000
Family
5/22/2009
HEP and Scientific Computing Grid, J. Yu

4. But still lots we don’t know…
Why are there three families of quarks and leptons?
Why is the mass range so large (0.1mp – 175 mp)?
How do all matters get the masses?
Higgs mechanism but where is the Higgs, the God particle?
Why does universe only made of particles?
What happened to anti-particles? Or anti-matters?
Why are there only three apparent forces?
Is the picture we present the real thing?
How is the universe created?
Are there any other theories that describe the universe better?
5/22/2009
HEP and Scientific Computing Grid, J. Yu

5. What are the roles of particle accelerators?
Act as a probing tool
The higher the energy The shorter the wavelength
Smaller distance to probe
Two method of accelerator based experiments:
Collider Experiments: pp, pp, e+e-, ep
CMS Energy = 2sqrt(E1E2)
Fixed Target Experiments: Particles on a target
CMS Energy = sqrt(2EMp)
Each probes different kinematic phase space -
5/22/2009
HEP and Scientific Computing Grid, J. Yu

6. The International Linear Collider
An electron-position collider on a straight line
CMS Energy: 0.5 – 1 TeV
10~15 years from the approval of the project
Takes 10 years to build the accelerator and the detector
L~31km
May 25, 2009
GEM DHCAL Development; J. Yu

7. ILC Physics Topics and Requirements
International Linear Collider is the next generation machine for precision measurement in high
Critical physics measurements
Higgs production e.g. e+ e- Zh  qqbb
Separate from WW, ZZ (in all jet modes)
Precision higgs couplings measurements
gtth from e+ e-  tth  WWbbbb  qqqqbbbb
ghhh from e+ e-  Zhh qqbbbb
Precision higgs branching ratios h  bb, WW*, cc, γγ, tau tau
etc
All of these physics goals demand
Efficient jet separation and reconstruction
Excellent jet energy resolution
Excellent jet-jet mass resolution
May 25, 2009
GEM DHCAL Development; J. Yu

8. Can Traditional Calorimeter Meet the Requirements?
Mj1j2
Mj3j4
60%/√E
Mj1j2
Mj3j4
30%/√E
May 25, 2009
GEM DHCAL Development; J. Yu

9. Traditional Calorimeter Systems
Equalized EM and HAD responses (“compensation”)
Jets are measured through calorimeter alone
Optimized sampling fractions
ZEUS – Uranium /Scintillator
Single hadrons 35%/√E + 1%
Electrons 17%/√E + 1%
Jets 50%/√E
DØ – Uranium/Liquid Argon
Single hadrons 50%/√E + 4%
Jets 80%/√E
Significant improvement is needed for LC ~30%/√E
New approach is necessary to meet the requirement
May 25, 2009
GEM DHCAL Development; J. Yu

10. GEM DHCAL Development; J. Yu
Particle Flow Algorithms
The idea… KL
Charged particles Tracker
measured with the
Neutral particles Calorimeter
HCAL
ECAL π+ γ
Particles in jets
Fraction of energy
Measured with
Resolution [σ2]
Charged
65 %
Tracker
Negligible
Photons
25 %
ECAL with 15%/√E
0.072 Ejet
Neutral Hadrons
10 %
ECAL + HCAL with 50%/√E
0.162 Ejet
Confusion
≤ Ejet
18%/√E
Required for 30%/√E
Requirements on detector
→ Need excellent tracker and high B – field
→ Large RI of calorimeter
→ Calorimeter inside coil
→ Calorimeter with extremely fine segmentation
Figure of merit BRI2
May 25, 2009
GEM DHCAL Development; J. Yu

11. Gas Electron Multipliers
GEM foil etching
140μm
70μm
GEM field and multiplication
65μm
Gains
May 25, 2009
From CERN-open , A. Sharma
GEM DHCAL Development; J. Yu

12. How does GEM Chamber work?
Ionization
Charged track
-2100V
∆V ~400V 0V
Ionization
How large is the electric field across a GEM foil? e-
E=V/d
=400V/6x10-5cm~6.7x105V/cm
Sensitive to a wide range of particles, from low E γ-rays and X-rays to several TeV charged particles
Flexible with high position resolution and high efficiency  Good imaging device
Relatively low operational voltage
Can operate with normal operational gas – ArCO2 or other noble gasses (such as Xe)
Short response time ~ 50ns
High gain (102
Robust to high flux radiation
May 25, 2009
GEM DHCAL Development; J. Yu

13. { GEM-based Digital Calorimeter Concept Use Double GEM layers ~6.5mm
May 25, 2009
GEM DHCAL Development; J. Yu

14. GEM DHCAL Development; J. Yu
UTA 30cm x 30cm 3M GEM foils
12 HV sectors on one side of each foil.
Magnified section of a 3M GEM foil.
May 25, 2009
GEM DHCAL Development; J. Yu
HV Sector Boundary

15. Absolute Efficiency vs Threshold w/ 120GeV P
MPV=17.1+/-0.36fc fC
MPV=20.1+/-0.41fc
100 4 fC
May 25, 2009
GEM DHCAL Development; J. Yu

16. GEM DHCAL Development; J. Yu
UTA GEM Chamber Gain
80/20 ArCO2
g=(1.16+/-0.024)10^4
May 25, 2009
GEM DHCAL Development; J. Yu

17. GEM DHCAL Development; J. Yu
High Density KPiX Analog Readout for GEM DHCAL
Dynamic gain select (GEM/Si)
13 bit A/D
DHCAL anode pad
Storage until end of train.
Pipeline depth presently is 4
Leakage current subtraction
Reset in regular period
Event triggered by the ILC clock
calibration
1024 channel 13 bit ADC chip
Developed for Si/W SLAC
May 25, 2009
GEM DHCAL Development; J. Yu 17

18. GEM-DHCAL/KPiX boards with Interface and FPGA boards
May 25, 2009
GEM DHCAL Development; J. Yu

19. GEM with High Density Analog Readout KPiX
Understand the chip’s behavior using calibration data
Data taken hourly for two separate days + three months
Time dependence of calibration parameters for each channel, Pedestal Mean, Sigma; Gain, and Y-Intercept in numerous gains mode studied
Relatively stable short term time dependence of ped and gains for the given channel but some long term ped change observed
Significant channel-to-channel gain variations (5 – 20 ADC/fC) observed
May 25, 2009
GEM DHCAL Development; J. Yu 19

20. Channel to Channel Variations
<Ped>
<Gains>
5 – 20ADC/fC
20 – 130 ADC
Channel #

21. GEM with High Density Analog Readout KPiX
Understand the chip’s behavior using calibration data
Data taken hourly for two separate days + three months
Time dependence of calibration parameters for each channel, Pedestal Mean, Sigma; Gain, and Y-Intercept in numerous gains mode studied
Relatively stable short term time dependence of ped and gains for the given channel but some long term ped change observed
Significant channel-to-channel gain variations (5 – 20 ADC/fC) observed
Analysis of KPiX data complicated due to
Its triggering scheme using accelerator clock
Thus, no external triggering scheme
How do you trigger weak radioactive source signal?
New version with external and self trigger scheme being characterized
May 25, 2009
GEM DHCAL Development; J. Yu 21

22. KPiX Self Trigger Threshold and Noise Scan
Threshold at -2.0V most optimal
Observe clear Landau distribution of β from Ru106
1.8V
1.9V
2.0V
2.1V
2.2V
2.3V
Ru106 Source
Noise
May 25, 2009
GEM DHCAL Development; J. Yu

23. HV dependence of Fe55 spectrum
No obvious two characteristic X-ray peaks (4 and 5.9KeV)
May 25, 2009
GEM DHCAL Development; J. Yu

24. Cosmic Ray Data with External Trigger0V
May 25, 2009
GEM DHCAL Development; J. Yu

25. GEM DHCAL Development; J. Yu
GEM DHCAL Plans - I
Through Fall 2009
30cmx30cm chamber
Construct a new chamber with optimal gas flow design
Characterize the chamber with sources and cosmic rays using 64 channel KPiX v7 at UTA
Characterize the chamber in particle beams
Responses, noise characteristics, efficiencies, gains, etc
33cmx100cm unit chamber
Finalize 33cmx100cm (32cmx96cm active area) large GEM foil silkscreen design
Design being finalized  production this summer
May 25, 2009
GEM DHCAL Development; J. Yu

26. Gas Transparent Spacers
Pathway for gas
Room for HV lead wire
Space for HV soldering
GEM foil
Grid thickness: 1 mm
Gas hole between adjacent cell:
5x1 mm2 for 3 mm spacer
5x1 mm2 for 2 mm spacer
5x0.5 mm2 for 1 mm spacer

27. Gas outlet
Top side
Data cable
HV power
LV power
Analog signal

28. Large GEM Foil Discussion with CERN-GDD
The size of the foils are 33cmx100cm, the same as the physical size of the unit chamber
Active area is 32cmx96cm
Is this realistic to think of constructing a chamber with the same physical size foils?
Rui de Oliveira says that the foils will be delivered in eight weeks or so once the design is completed and once the hole etching technique is verified
One-side hole etching technique is being improved  Since gain shows factor two difference
May 25, 2009
GEM DHCAL Development; J. Yu

29. Large GEM Foil Draft Design
Active area = 990x329.9 mm2
We need copper region and some markings for GEM alignment.
We can reduce the number of sectors. It’s 33 currently.

30. GEM DHCAL Development; J. Yu
GEM DHCAL Plans - II
Fall 2009 – Mid 2010
33cmx100cm thin GEM unit chambers
Production and certification of 33cmx100cm foils
Characterization of 256 channel v8 KPiX chips
Available in later in 2009
Use 30cmx30cm STP chamber
Construction and characterization of 33cmx100cm thin GEM unit chamber
Large Thick GEMs
Working with Weizman institute on TGEMs
Certification of large TGEMs
May 25, 2009
GEM DHCAL Development; J. Yu

31. GEM DHCAL Development; J. Yu
UTA’s 33cmx100cm DHCAL Unit Chamber
Readout Board
330x500 mm2
1000 mm
Base steel plate, t=2 mm
330 mm
May 25, 2009
GEM DHCAL Development; J. Yu

32. GEM DHCAL Development; J. Yu
GEM DHCAL Plans - III
Mid 2010 – Mid 2011
33cmx100cm thin GEM unit chambers
Complete production of 15 33cmx100cm unit chambers
Construct five 100cmx100cm GEM DHCAL planes
Using DCAL or KPiX readout chips
Beam test GEM DHCAL planes in the CALICE beam test stack together with RPC
TGEMs and RETGEMs
Construction and characterization of a prototype chamber using an analog readout chip
Beam test of TGEM prototype chamber
May 25, 2009
GEM DHCAL Development; J. Yu

33. GEM DHCAL Development; J. Yu
UTA’s 100cmx100cm Digital Hadron Calorimeter Plane
May 25, 2009
GEM DHCAL Development; J. Yu

34. GEM DHCAL Beam Test Plans
Phase I  Completion of 30cmx30cm characterization
Fall 2009 at MTBF: using one plane of 30cmx30cm double GEM chamber with 64 channel KPiX7
Phase II  33cmx100cm unit chamber characterization
Late 2009 – mid 2010 at MTBF: Using 256 channel v8 KPiX chips
Possible beam test and characterization of TGEM prototype using 256 channel v8 KPiX chips
Phase III  100cmx100cm plane GEM DHCAL performances in the CALICE stack
Late 2010 – Mid 2011 at MTBF
Five 100cmx100cm planes inserted into existing CALICE calorimeter stack and run with either Si/W or Sci/W ECALs and RPC planes in the remaining HCAL
May 25, 2009
GEM DHCAL Development; J. Yu

35. GEM Application Potential
FAST X-RAY IMAGING
Using the lower GEM signal, the readout can be self-triggered with energy discrimination:
9 keV absorption radiography of a small mammal (image size ~ 60 x 30 mm2)
A. Bressan et al,
Nucl. Instr. and Meth. A 425(1999)254
F. Sauli, Nucl. Instr. and Meth.A 461(2001)47
May 25, 2009
GEM DHCAL Development; J. Yu 35

36. How is HEP relevant to Radiology?
CCD camera
1:1 relay lens
Image Intensifier
Phosphor screen/scintillator
May 25, 2009
GEM DHCAL Development; J. Yu
M. Lewis

37. Scintillation events are faint
4.8mm
6.8mm
Optical penalty for a large FOV with a small sensor. With a 30mm x 30mm FOV, the events would be 25-36x dimmer, and would be undetectable in the noise  Optical amplification is essential.
May 25, 2009
GEM DHCAL Development; J. Yu

38. GIA, The Goddess of the Earth
GIA, GEM-based Image Amplifier
Improve the resolution of small animal radiation imaging using GEM based Image Amplifier
Replace small aperture microchannel-based image intensifier with a GEM-based detector, increasing field of view
Convert γ-rays into electrons (photo converter)
Amplify the electron signal by as large as needed w/ GEM
Convert electron avalanche back to photons
Feed this to CCD camera
Move into embedded digital readout of signal using custom DAQ  computerized image
... γ
CCD
... γ
DAQ
May 25, 2009
GEM DHCAL Development; J. Yu

39. GIA/GIANT Chamber Design
Scintillator:CsI
S-20 photo-converter
Optical-back-converter: BaFBr:Eu2+
May 25, 2009
GEM DHCAL Development; J. Yu

40. GIA/GIANT Chamber Prototype
5cmx5cm active area
May 25, 2009
GEM DHCAL Development; J. Yu

41. GEM DHCAL Development; J. Yu
Conclusions
Gas Electron Multiplier technology has a remarkable potential to be used in high precision calorimetry
And to be used in other types of radiation detectors
Medical imaging, homeland security, etc
High density multi-channel GEM-KPiX combination being characterized
Ru106 and Fe55 source and cosmic runs are being understood
1mx33cm long foil development with CERN for 1mx1m unit chambers  Large area radiation detector
Beam test of large scale chambers expected in 2010 – 2011
Collaborating with UTSW Medical Center for medical imaging device development
Outcome and the bi-product of HEP research impacts our daily lives
WWW came from HEP
GIA chamber design complete
May 25, 2009
GEM DHCAL Development; J. Yu