UTA GEM DHCAL Simulation

1
UTA GEM DHCAL Simulation

• Jae Yu
• UTA DoE Site Visit
• Nov. 13, 2003

• Introduction
• GEM Geometry Implementation
• Single Pion Study for GEM performances
• GEM Analog Mode
• GEM Digital Mode
• Single Pion EFA Studies
• Summary

(On behalf of the UTA team A. Brandt, K. De, S.
Habib, V. Kaushik, J. Li, M. Sosebee, A. White)
2
Introduction

• LC physics topics require excellent jet energy
  and angular resolutions
• Energy flow algorithm is one of the solutions
• Large number of readout channel will drive up the
  cost for analogue style energy measurement ?
  Digital HCAL
• Tracking calorimeter with high gain sensitive gap
• GEM is one such detector technology
• Simulation effort to understand detector
  progressed along with prototype development
• Thanks to the support from LCRD and ADR

3
UTA GEM Simulation

• LC Physics Events Pandora Phythia
• Use Mokka as the primary tool
• Kept the same detector dimensions as TESLA TDR
• Replaced the HCAL scintillation counters with GEM
  (18mm SS 6.5mm GEM, 1cmx1cm cells)
• Single Pions used for performance EFA studies
• 5 100 GeV single pions
• Analyzed them using ROOT

4
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 Calorimeter
• Material
• 18 mm of Fe
• 6.5 mm of Polystyrene scintillator (in green)

5
UTA Double GEM Geometry
25.2sec/event for Simple GEM v/s 43.7 sec/event
for Detailed GEM
6
Energy Deposit for 10 GeV Pions (GEM)
fEMgt0.85
fHCgt0.85
Total
Remaining
7
GEM-Digital Elive vs of hits for p-
8
GEM Cell Occupancies
74 single hit
26 gt1 hit
Number of cells with higher number of hits
increase w/ E
9
Energy Deposit/Ncells vs Layers for 50 GeV Pions
10
Extraction of of dE/dN
11
EM-HAD Relative Weighting Factor

• To compensate the response differences between
  ECAL and GEM HCAL responses a procedure to
  normalize them had to be introduced
• ELiveSEEM W SgEHAD (gGEM Intrinsic gain)
• Obtained the relative weight W using two Gaussian
  fits to EM only v/s HAD only events
• Perform linear fit to Mean values as a function
  of incident pion energy
• Extract ratio of the slopes ? Weight factor W
• E C ELive

12
GEM Relative Weights
Analog
Digital
13
GEM-Digital Live Energy 50 GeV p-
14
GEM Normalized Response
Analog 2.4
Digital2.6
15
Converted energy 50 GeV p-
Analog
Digital
Fits are Landau Gaussian
16
Resolutions
17
EF Technique
Normal Calorimetric Method
C1
C2
C3
C4
C6
C5
Energy Flow Method
C7
p3
p2
p5
p7
18
Energy Flow Studies Using p-

• Charged particle energy subtraction based on
  track-cluster association is important to EFA
• The algorithm must work well with single particle
  case
• Pions ?E p- ? 7.5 GeV chosen for study
• Studied the energy distribution of pions in jet
  events
• Find the centroid of the shower ( HCAL ) using
• Energy weighted method
• Hits weighted method
• Density weighted method
• Match the extrapolated centroid with TPC last
  layer hit to get ?? and ?f distribution

19
Calorimeter Centroid Determination

• Energy Weighted Method
• Hit Weighted Method
• Density Weighted Method

20
Event Displays
6 jets
Single p
21
Number of charged and Neutral particles
ltNgt6
ltNgt12
Neutral particles
Charged e?, ??, K?
22
?R of all the particles relative to quark
23
Dh (E weighted vs Numerical Mean)
Ep 50 GeV 1cm x 1 cm cells
Analog seems to be better than digital but not by
significant factor
24
?? - 7.5 GeV p-
Energy Weighted
Hit Density Weighted
25
Summary

• Made a marked progress thanks to the LCRD and ADR
  support
• Completed single p GEM DHCAL performance studies
• Initial study documented in Habibs MS thesis
• More detailed and refined study being completed
  by Kaushik
• Analog resolution seems to be worse compared to
  other detector technology due to large
  fluctuation in initial ionization electrons
• Digital, however, performance is comparable to
  other analog technologies
• Released our Pandora Phythia ASCII and other
  analysis packages to LC software group per their
  request

26

• EFA studies in progress
• Study track cluster association and energy
  subtraction using single pion ? Three methods
  being investigated
• Study typical distance between charged particles
  within the jet
• Determine necessary resolving power for realistic
  situation
• Prepare for larger scale prototype, cosmic ray
  stack and TB simulation
• Development of analysis software
• Continued and increased support is critical to
  make the next quantum jump