The GLD Concept

1
The GLD Concept
2
MDI Issues

• Impact on Detector Design
• L ? Background (back-scattered e- ,g, n) into
  VTX, TPC
• Crossing angle ? Minimum veto angle for 2-photon
  process (important for SYSY search),
  back-scattered e- into VTX
• Pair background ? VTX radius
• Synchrotron radiation ? Beam pipe / VTX radius,
  background hits in trackers
• Muons ? Detector hit occupancy
• Neutrons from the extraction line ? Radiation
  damage on Si
• DID ? TPC resolution
• Anti-solenoid ? Design of very forward detectors
• Beam timing ? Readout scheme of VTX, etc.
• etc.
• GLD detector concept study includes all these
  issues.
• The baseline design should be compatible with the
  most severe case High Lumi option

3
Requirement from Physics

• Impact parameter sb 5 ? 10/(pb sin3/2q ) mm
• (c/b-tagging)
• Momentum spt/pt2 5x10-5 /GeV
• (e.g. H recoil mass reconstruction from
  Z?m pairs)
• Jet energy sE/E 30/E1/2
• (W/Z invariant mass reconstruction from
  jets)
• Hermeticity q5 mrad
• (for missing energy signatures, e.g.
  SUSY)

• Sufficient timing resolution to separating events
  from different bunch-crossings
• Must also be able to cope with high track
  densities due to high boost and/or final states
  with 6 jets, therefore require
• High granularity
• Good pattern recognition
• Good two track resolution

• General consensus Calorimetry drives ILC
  detector design

4
Calorimetry at the ILC

• Much ILC physics depends on reconstructing
  invariant masses from jets in hadronic final
  states
• Kinematic fits wont necessarily help Missing
  particles (e.g. n) Beamstrahlung, ISR
• Aim for jet energy resolution GZ for typical
  jets
• Jet energy resolution is the key to calorimetry
• The best jet energy resolution is obtained by
  reconstructing momenta of individual particles
  avoiding double counting
• Charged particles (60) by tracker
• Photons (30) by ECAL
• Neutral hadrons (10) by ECALHCAL
• ? Particle Flow Analysis
• The dominant contribution to jet energy
  resolution comes from confusion, not from
  single-particle resolution of CAL
• Separation of particles by fine segmentation /
  large distance from the IP is important for CAL

5
Calorimetry Optimization for PFA

• To avoid the confusion and get good jet energy
  resolution, separation of particles is important
  for CAL How?
• Fine segmentation of CAL
• High B field
• Large distance from the IP ? Large Detector

Often quoted Figure of Merit
s CAL granularity RM Effective Moliere length
6
Calorimetry B or R?

• B-field just spreads out energy deposits from
  charged particles in jet not separating neutral
  particles or collinear particles
• Detector size is more important spreads out
  energy deposits from all particles
• R is more important than B

GLD Concept Investigate detector parameter
space with large detector size (R) and slightly
lower magnetic field (B) and granularity
7
GLD Baseline Design

• Large gaseous central tracker TPC
• Large radius, medium/high granularity ECAL
  W-Scint.
• Large radius, thick(6l), medium/high granularity
  HCAL Pb-Scint.
• Forward ECAL down to 5mrad
• Precision Si micro-vertex detector
• Si inner/forwad/endcap trackers
• Muon detector interleaved with iron structure
• Moderate B-field 3T

VTX, IT not shown
8
Vertex detector

• Role Heavy flavor tagging
• Important for many physics analyses e.g. Higgs
  branching ratio measurement
• Efficient flavor tagging requires excellent
  impact parameter resolution
  
• Goal s 5 ? 10/(pb sin3/2q ) mm
• Sensor technologies
• Must cope with high background rate
• Readout 20 times/ train, or
• Fine pixel (20 times more pixels) option
  readout once/ train

9
Vertex detector

• Main design consideration
• Inner radius
• Beam pipe radius Dense core of pair background
  should not hit the beam pipe
• B-dependence not so large B-1/2
• Large machine-option dependence
• Back scattered e- from BCAL (Low-Z mask in front
  of BCAL should cover down to RltRVTX )
• Layer thickness
• As thin as possible to minimize multiple
  scattering
• ? I.P. resolution / tracking efficiency for low
  p particles
• GLD baseline design
• Fine pixel CCD
• Inner/outer radius 20(?) 50 mm
• Angle coverage cosqlt0.9/0.95

10
Si trackers

• Role Cover large gap between
• TPC and VTX ? Si Inner Tracker (IT)
• TPC and endcap ECAL ? Si Endcap Tracker (ET)
• to get better
• Track finding efficiency
• Momentum resolution
• Track-cluster maching in ECAL (PFA)
• Design optimization
• Number of layers and their position
• Wafer thickness
• Strip or pixel? for the very forward region

11
Main tracker TPC

• Performance goal
• spt/pt2 5x10-5 /GeV
• combined with IT and VTX
• Advantages of TPC
• Large number of 3D sampling
• Good pattern recognition
• Identification of non-pointing tracks (V0 or kink
  particles) e.g. GMSB SUSY
• Good 2-hit resolution
• Minimal material
• Particle ID using dE/dx

e e- ? ZH ? m m X
12
TPC

• Baseline design
• Inner radius 40 cm
• Outer radius 200 cm
• Half length 230 cm
• Readout 200 radial rings
• Open questions
• Readout GEM or Micromegas?
• Material budget of inner/outer wall and end plate
• Background hit rate and its effect on spatial
  resolution due to positive ion buildup (occupancy
  is OK even with 105 hits in 50ms)

13
Tracking performance

• GLD conceptual design achieves the goal of
  spt/pt2 5x10-5 /GeV

14
Calorimeter

• Performance requirement
• Goal for jet energy resolution is sE/E 30/E1/2
• Then, what is the requirement for CAL?
• The answer is not simple. We need a lot of
  simulation study of PFA

15
ECAL

• Current baseline design
• 33 layers of 3mm W 2mm Scinti. 1mm gap
  (readout elec.)
• 28 X0, 1 l, RM18mm
• Wavelength shifter fiber MPC (Multi-pixel
  Photon Counter, SiPM) readout
• 4cmx4cm tile and 1cm-wide strips
• Granularity has to be optimized by PFA simulation
  study
• Calibration method for small segments is
  worrisome
• Very fine segmentation with Si for first few X0
  is also discussed

MPC 400pixels
MPC 100pixels (10x10pixels)
16
HCAL

• Current baseline design
• 50 layers of 20mm Pb 5mm Scinti. 1mm gap
  (readout elec.) (Hardware compensation
  configuration)
• 6 l
• Wavelength shifter fiber MPC (Multi-pixel
  Photon Counter, SiPM) readout
• 20cmx20cm tile and 1cm-wide strips
• Granularity has to be optimized by PFA simulation
  study
• Digital HCAL is also considered as an option
• Open questions
• Global shape Octagon, dodecagon, or hexadecagon?
• How to extract cables?

Hamamatsu MPC (H100) spectrum Up to 40 photon
peak! is observed
17
FCAL/BCAL

• BCAL
• Locates just in front of final Q
• Coverage down to 5mrad
• W/Si or W/Diamond (No detailed design yet)
• FCAL
• Z2.3m
• Also work as a mask protecting TPC from
  back-scattered photon from BCAL
• W/Si (No detailed design yet)

18
Muon detector / Magnet

• Muon detector
• Possible technology Scintillator strip array
  read out with wavelength shifter fiber MPC
• Number of layers, detector segmentation, etc.
  have to be studied
• Magnet
• 8 mf 3T superconducting solenoid
• Stored energy 1.6 GJ
• Excellent field uniformity for TPC

19
Cost Issues

• Major cost consumers Solenoid, HCAL, ECAL
• Solenoid
• Cost0.523xE(MJ)0.662 PDG70M
• HCAL
• Volume230m3, Area (all layers)87Mcm2
• Cost87M x cost/cm2
• ECAL
• Volume22m3, Area (all layers)37Mcm2
• Cost37M x cost/cm2
• Requirement for granularity from physics
  determines the CAL design and the cost
  Simulation study is urgent

20
Summary

• GLD design study is being carried out both from
  accelerator point of view and from physics point
  of view
• ILC detectors should be optimized for PFA
  performance, and large detectors are suitable for
  that
• In GLD concept study, we investigate detector
  parameter space with large detector size and
  slightly lower B and CAL granularity
• Baseline design of GLD has been shown, but
  current GLD baseline design is not really
  optimized. More simulation study, sub-detector
  RD effort, and new ideas are necessary
  ?The purpose of this workshop