digital hcal using gem j. yu* univ. of texas at arlington nov. 7 - 9, 2002 nicadd/niu (*on behalf of...
TRANSCRIPT
Digital HCAL using GEM J. Yu*
Univ. of Texas at ArlingtonNov. 7 - 9, 2002
NICADD/NIU
(*on behalf of the UTA team; A. Brandt, K. De, S. Habib, V. Kaushik, J. Li, M. Sosebee, A. White)
•Introduction•Digital Hadron Calorimeter Requirements•GEM in the sensitive gap•UTA GEM DHCAL Prototype Status•Simulation Status •Plans for Hardware, Simulation & Algorithms•Summary
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 2
Introduction• LC physics topics
– Distinguish W from Z in two jet final states Good jet mass resolution– Higher Jet energy resolution;– Excellent jet angular resolution
• Energy flow algorithm is one of the solutions– Replace charged track energy with momentum measured in the tracking
system• Requires efficient removal of associated energy cluster • Higher calorimeter granularity
– Use calorimeter only for neutral particle energies– Best known method for jet energy resolution improvement
• Large number of readout channel will drive up the cost for analogue style energy measurement Digital HCAL
• Tracking calorimeter with high gain sensitive gap
JetJet EE%30~
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 3
DHCAL General Requirements• Thin and sensitive readout layer for compact design• One or two level digital hit recording for EFA use• On-board amplification, digitization and discrimination
for readout, minimizing noise and cross-talk• Flexible design for easy implementation of arbitrary cell
size for upgrade• Minimal intrusion for crackless design• Ease of construction and maintenance• Cost effective
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 4
DHCAL Gas Amplification Requirements • Sufficiently large gain for good S/N ratio (3 orders of magnitude
smaller signal in gas compared to scintillation counter)• Minimize cross-talk between cells in readout• Isolated readout path from active volume to avoid coherent noise• Modularity, retaining continuity for gas and HV supplies and
readout• Digitized readout from each cell• Allow pad design to avoid strip ambiguity• Keep low HV for safety and reliability• Simple readout electronics for cost savings and reliability
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 5
• Small cell size for higher position resolution for good multiple track shower separation
• High efficiency for MiPs in a cell for effective shower particle counting and MiP tracking
• Possibility for Multiple thresholds• Dense and compact design for quick shower development
to minimize confusion and resolution degradation • Large tracking radius with optimized magnetic field for
sufficient separation between tracks for shower isolation
DHCAL Requirements for EFA
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 6
Goals for UTA DHCAL Development• Develop digital hadron calorimetry for use with EFA
– Aim for cost effectiveness and high granularity– Look for a good tracking device for the sensitive gap
• Develop GEM cell(s) and prototype• Develop module/stack design for EFA optimization• Simulate GEM behavior in calorimeter• Implement GEM readout structure into simulation• Develop EF and calorimeter tracking algorithms• Cost effective, large scale GEM DHCAL
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 7
Why GEM?• GEM developed by F. Sauli (CERN) for use as pre-amplification
stage for MSGC’s• Allow flexible and geometrical design, using printed circuit
readout Can be as fine a readout as GEM tracking chamber!!• High gains, above 104,with spark probabilities per incident less
than 10-10
• Fast response– 40ns drift time for 3mm gap with ArCO2
• Relative low HV– A few 100V per each GEM gap compared to 10-16kV for RPC
• Rather reasonable cost– Foils are basically copper-clad kapton– ~$400 for a specially prepared and framed 10cmx10cm foil
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 8
CERN-open-2000-344, A. Sharma
Large amplification
70m
140m
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 9
GEM Foils• Most foils made at CERN• A total of about 1000 foils
made• COMPASS experiment has
large scale, 31cmx31cm, GEM
• Kapton etching most difficult step Work with Sauli’s group
A. Sharma CERN OPEN-98-030
r=70m
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 10CERN GDD group
GEM gains
Low voltage differential!!
High gain
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 11
Double GEM DHCAL Design
Ground to avoid cross-talk
Embeded onboard readout
AMP DISC
REG
Digital/serial output
Thr. Thr.
Anode pad
Ground
REG
AMP DISC
Preliminary readout design
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 12
Double GEM test chamber
J. Li, UTA
•Sufficient space for foil manipulation•Readout feed-through, retaining large space for ease of connection•Clear cover to allow easy monitoring•Readout pads connection at the bottom
2cmx2cm pad design
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 13
UTA GEM Test Chamber HV layout
2.1kVDrift gap
Transfer gap
Induction gap
HV fed from one supply but individually adjusted Good to prevent HV damage on the foils
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 14
UTA GEM Prototype Status
• Readout circuit board (2cmx2cm pads) constructed
• HV Connection implemented
• Two GEM foils in the UTA Nano fabrication facility cleanroom
• Preamp in hand and characterization completed
Amplification factor of 300 for GEM size signal (LeCroy HQV800 )
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 15
Single GEM gain/discharge probability
A.Bressan et al, NIM A424, 321 (1998)
Simulation study in progress using multi-jet final states•Understand average total charge deposit in a cell of various sizes•Study fake signal from spiraling charged particle in the gap
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 16
UTA Simulation Status • Two masters students have been working on this
project– Mokka Geometry database downloaded and installed at UTA– Preliminary mixture GEM geometry implemented– Completed single pion studies using default geometry
• Reproduced expected response• Energy resolution seems to be reasonable also
• Root macro based and JAS based analysis packages developed
• Proceed with more detailed GEM geometry implementation
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 17
Single Pion Studies w/ Default TESLA Geometry
• 1000 single pion events using Mokka particle gun command. – Incident energy range: 5 – 200GeV– kinematics information on primary particles in the files
• Developed an analysis program to read total energies deposited per pion for each incident energy.– Mean Energy vs Incident pion energies – Energy conversion from the slope of the straight line– Conversion factor is 3.54% and agrees with the computed
sampling fraction
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 18
TESLA TDR Geometry
Ecal – Electromagnetic Calorimeter Material: W/G10/Si/G10 plates (in yellow)•1mm W absorber plates•0.5 mm thick Si, embeded 2 G10 plates of 0.8 mm each
Hcal – Hadronic CalorimeterMaterial:•18 mm of Fe •6.5 mm of Polystyrene scintillator (in green)
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 19
TESLA TDR detector live energy deposit for single pions
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 20
TESLA TDR Elive vs E
%
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 21
TESLA TDR CAL Single Pion Resolution
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 22
GEM Simulation Status • Mokka Geometry database downloaded and installed at UTA• New Geometry driver written Mixture GEM geometry
implemented Need to use ArCO2 only• Single pion study begun for discharge probability
– Initial study shows that the number of electron, ion pair with gain of 104 will be on the order of 107 for single 200GeV pions
– Getting pretty close to the 108 from other studies Might get worse for jets from W pairs, due to fluctuation
– Need more studies to compute the discharge probability.• Cell energy deposit being investigated to determine optimal
threshold based on cell energy Proceed to energy resolution studies
• Determine optimal gain using live energy deposit vs incident energy
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 23
GEM Prototype Geometry
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 24
GEM Geometry Implementation Mechanics in Mokka
TDR / Hcal02 Model chosen for modification
Fe-GEM sub-detector instead of the existing Fe-ScintillatorNew driver for the HCal02 sub-detector moduleLocal database connectivity for HCal02 Database downloaded and implemented at UTA
Courtesy: Paulo deFrietas
Venkat, TSAPS Meet Oct 10 - 12, 2002
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 25
Single pion study with GEM
15GeV
5GeV
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 26
Cell Energy Deposit in GEM HCal
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 27
GEM Sampling Weight
GEM Sampling Weight
y = 3.9373x + 51.969
0
50
100
150
200
250
300
0 10 20 30 40 50 60
Incident Pion Energy (GeV)
Liv
e E
ner
gy
Dep
osi
t (M
eV)
Series1
Linear (Series1)
Nov. 7, 2002 Jae Yu: GEM Based DHCAL 28
Summary• Hardware prototype making significant progress
– GEM foils delivered and are in the clean room for safe keeping– Preamp and Discriminator in hands Preamp characterized– HV System implemented– Readout Pad implemented– Almost ready to put GEM foils in the prototype box– GEM foil mass production being looked into by 3MSimulation effort made a marked
progress• Simulation effort made a marked progress
– Single pion study of Mokka default TESLA TDR geometry complete• Analysis tools in place• The resolution seems to be reasonable
– Preliminary GEM Mixture geometry implemented• First results seems to be a bit confusing
– Initial estimate of e+Ion pair seems to be at about 107 for 200GeV pions– Local Geometry database implemented– Optimal threshold for digitization and gain will come soon– Will soon move onto realistic events, WW, ZZ, or tt jets