1. JPS2006 @ Sheraton Waikiki Hotel
Detector Optimization using
Particle Flow Algorithm for ILC
Contents
1. Introduction
2. Particle Flow Algorithm
3. Results
4. Summary
DPF2006+JPS2006
@ Sheraton Waikiki Hotel
Oct. 29th-Nov. 3rd, 2006
Tamaki Yoshioka
ICEPP, Univ. of Tokyo
On behalf of GLD Colleagues
10/31/2006
Sheraton Waikiki Hotel

2. JPS2006 @ Sheraton Waikiki Hotel
Introduction
Most of the important physics processes to be studied in the ILC
experiment have multi-jets in the final state.
→ Jet energy resolution is the key in the ILC physics.
The best energy resolution is obtained by reconstructing
momenta of individual particles avoiding double counting among
Trackers and Calorimeters.
- Charged particles (~60%) measured by Tracker.
- Photons (~30%) by electromagnetic CAL (ECAL).
- Neutral hadrons (~10%) by ECAL + hadron CAL (HCAL).
→ Particle Flow Algorithm (PFA)
In this talk, general scheme and performance of the GLD-PFA,
using the GEANT4-based full simulator (Jupiter), will be presented.
10/31/2006
Sheraton Waikiki Hotel

3. JPS2006 @ Sheraton Waikiki Hotel
GLD Detector
Muon detector
- One of the detector concepts
for the ILC experiment.
The world-wide consensus of
the performance goal for the
jet energy resolution is
For more detail, please
see the GLD Detector
Outline Document (DOD)
→ physics/
Calorimeter
Coil
Vertex
detector
Tracker
GLD detector
10/31/2006
Sheraton Waikiki Hotel

4. JPS2006 @ Sheraton Waikiki Hotel
GLD Detector Concept
To get good energy resolution by PFA, separation of particles (reducing the
density of charged and neutral particles at CAL surface) is important.
Often quoted “Figure of Merit”
B : Magnetic field
R : CAL inner radius
σ: CAL granularity
RM : Effective Moliere length
GLD concept
1. Large inner radius of ECAL to optimize the PFA.
2. Large tracker for excellent dpt/pt2 and pattern recognition.
3. Moderate B field (~3T).
10/31/2006
Sheraton Waikiki Hotel

5. GLD Geometry in Jupiter
Solenoid
TPC
Hadron Calorimeter (HCAL)
VTX, IT
Muon Detector
Electromagnetic Calorimeter (ECAL)
Dodecagonal Shape
As of October 06
10/31/2006
Sheraton Waikiki Hotel

6. Calorimeter Geometry in Jupiter
Readout Line =10cm
349.4cm
Barrel HCAL
229.8cm
Barrel ECAL
210cm
270cm
Endcap HCAL
Barrel.InnerRadius=210cm
Endcap ECAL
Endcap.InnerRadius=40cm IP
Barrel.HalfZ=280cm
419.4cm
280cm
299.8cm
10/31/2006
Sheraton Waikiki Hotel

7. Calorimeter Structure
Active Layer
Absorber
Current cell size :
2x2cm
Can be changed.
ECAL
W/Scinti./Gap
3/2/1 (mm) x 33 layers
HCAL
Fe/Scinti./Gap
20/5/1 (mm) x 46 layers
10/31/2006
Sheraton Waikiki Hotel

8. JPS2006 @ Sheraton Waikiki Hotel
Z-pole Event Display
End View
Side View
- Z → qq 91.2GeV, tile calorimeter, 2cm x 2cm tile size
10/31/2006
Sheraton Waikiki Hotel

9. Particle Flow Algorithm for GLD
Flow of GLD-PFA
Photon Finding
Charged Hadron Finding
Neutral Hadron Finding
Satellite Hits Finding
*Satellite hits = calorimeter hit cell which does not belong
to a cluster core
Note : Monte-Carlo truth information is used for muon
and neutrino.
10/31/2006
Sheraton Waikiki Hotel

10. JPS2006 @ Sheraton Waikiki Hotel
Photon Likelihood
- Five variables are selected to form the photon likelihood function.
Track Distance
Velocity
Mean Layer
Photon
Other
Edep/Nhits
chi2
Output
Other
Photon
10/31/2006
Sheraton Waikiki Hotel

11. Particle Flow Algorithm for GLD
Flow of GLD-PFA
Photon Finding
Charged Hadron Finding
Neutral Hadron Finding
Satellite Hits Finding
*Satellite hits = calorimeter hit cell which does not belong
to a cluster core
Note : Monte-Carlo truth information is used for muon
and neutrino.
10/31/2006
Sheraton Waikiki Hotel

12. Charged Hadron Finding
Basic Concept :
Extrapolate a charged track and calculate a distance between
a calorimeter hit cell and the extrapolated track. Connect the cell
that in a certain tube radius (clustering).
Extrapolated Track
Calculate the distance
for any track/calorimeter
cell combination.
HCAL
Tube Radius
Hit Cells
Tube radius for ECAL
and HCAL can be changed
separately.
distance
ECAL
Calorimeter input position
Charged Track
10/31/2006
Sheraton Waikiki Hotel

13. Particle Flow Algorithm for GLD
Flow of GLD-PFA
Photon Finding
Charged Hadron Finding
Neutral Hadron Finding
Satellite Hits Finding
*Satellite hits = calorimeter hit cell which does not belong
to a cluster core
Note : Monte-Carlo truth information is used for muon
and neutrino.
10/31/2006
Sheraton Waikiki Hotel

14. Neutral Hadron Likelihood
- Four variables are selected to form the NHD likelihood function.
Output
Velocity
Energy Density
Satellite
Hits
Neutral
Hadron
Edep/Nhits
Mean Layer
Neutral Hadron
Satellite Hits
10/31/2006
Sheraton Waikiki Hotel

15. Particle Flow Algorithm for GLD
Flow of GLD-PFA
Photon Finding
Charged Hadron Finding
Neutral Hadron Finding
Satellite Hits Finding
*Satellite hits = calorimeter hit cell which does not belong
to a cluster core
Note : Monte-Carlo truth information is used for muon
and neutrino.
10/31/2006
Sheraton Waikiki Hotel

16. JPS2006 @ Sheraton Waikiki Hotel
Event Display e+ e-
Yellow : Photon
Red, Green : Charged Hadron
Black, Blue : Neutral Hadron
Z → 91.2GeV
10/31/2006
Sheraton Waikiki Hotel
Next: 電子、陽電子衝突

17. JPS2006 @ Sheraton Waikiki Hotel
Event Display
Yellow : Photon
Red, Green : Charged Hadron
Black, Blue : Neutral Hadron
Gamma Finding
10/31/2006
Sheraton Waikiki Hotel

18. JPS2006 @ Sheraton Waikiki Hotel
Event Display
Yellow : Photon
Red, Green : Charged Hadron
Black, Blue : Neutral Hadron
Charged Hadron Finding
10/31/2006
Sheraton Waikiki Hotel

19. JPS2006 @ Sheraton Waikiki Hotel
Event Display
Yellow : Photon
Red, Green : Charged Hadron
Black, Blue : Neutral Hadron
Remove Satellite Hits
10/31/2006
Sheraton Waikiki Hotel

20. JPS2006 @ Sheraton Waikiki Hotel
Event Display
Yellow : Photon
Red, Green : Charged Hadron
Black, Blue : Neutral Hadron
Remaining : Neutral Hadron
10/31/2006
Sheraton Waikiki Hotel

21. Jet Energy Resolution (Z-pole)
- Z → 91.2GeV, tile calorimeter, 2cm x 2cm tile size
All angle
Almost no angular dependence : 31%/√E for |cosq|<0.9.
cf. 60 %/√E w/o the PFA (sum up the calorimeter energy)
10/31/2006
Sheraton Waikiki Hotel

22. JPS2006 @ Sheraton Waikiki Hotel
Performance
- Energy-weighted Efficiency and Purity
Definition
Efficiency : xxx  (total xx E in collected hits)/(true xxx total E in CAL)
Purity : Pxxx  (total xxx E in a cluster)/(total E in a cluster)
xxx = Photon, CHD, NHD, Satellite
both  and P values are energy-weighted
10/31/2006
Sheraton Waikiki Hotel

23. JPS2006 @ Sheraton Waikiki Hotel
Jet Energy Resolution
- Energy dependence of jet energy resolution.
- Jet energy resolution linearly degrades. → Need to improve.
10/31/2006
Sheraton Waikiki Hotel

24. JPS2006 @ Sheraton Waikiki Hotel
Summary
• Realistic PFA has been developed using the GEANT-4
based full simulator of the GLD detector.
• Jet energy resolution is studied by using Z→qq events.
ILC goal of 30% has been achieved in the barrel region
of the Z-pole events.
• By using the PFA, we are going to optimize the detector
parameters such as the calorimeter granularity, radius etc.
10/31/2006
Sheraton Waikiki Hotel