Angular resolution study of isolated gamma with GLD detector simulation 2007/Feb/ ACFA ILC Workshop...
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Transcript of Angular resolution study of isolated gamma with GLD detector simulation 2007/Feb/ ACFA ILC Workshop...
Angular resolution study Angular resolution study of isolated gamma with of isolated gamma with GLD detector simulationGLD detector simulation
2007/Feb/2007/Feb/
ACFA ILC WorkshopACFA ILC Workshop
M1 ICEPP, TokyoM1 ICEPP, Tokyo
Hitoshi HANOHitoshi HANO collaborated with Acfa-Sim-J group
Contents
Introduction Angular Resolution Study
position resolution of ECAL cluster direction of reconstructed gamma
Calorimeter Component DependenceCell size dependenceMaterial dependence
Summary
Motivation and PFA analysis
G~~ 0
1
Measurement of the direction of non-pointing photon is important for GMSB (gauge mediated supersymmetry breaking) scenarios.
To identify a non-pointing photon, we need to know angular resolution of the detector (EM Calorimeter).
We have studied angular resolution using full-simulator (Jupiter)
35 10~10 [m]
decay length :
ECAL
IP G~
01
~
G~
01
~
In this study, we have used single-gamma shot from IP to evaluate angular resolution.
Jupiter for GLD detectorGLD detector has large-radius and fine-segmented Calorimeter.
It’s important to optimize cost
vs. physics performance.
R [m] Z [m]
ECAL2.1-2.3
0.4-2.3
0-2.8
2.8-3.0
Structure
W/Scinti./gap3/2/1(mm) x 33 layers cell size 1x1(cm2)
ECAL geometry in Jupiter :
barrel
endcap
Calorimeter cell sizeand absorber material
can be changed.
IP (generated point)
1. Clustering
2. Find an energy-weighted central point of each layer
3. Fit each point with least-square method
4. Evaluate an angle between gamma-line and reconstructed gamma
Method of reconstructed gamma
γ
reconstructed gamma
Calorimeter
Angular Resolution Study
position resolution of cluster
Method (position resolution study of aaaaaaa each hit cluster)
1. Shoot single-gamma from IP with random direction
2. Clustering (more details in next page)
3. Search energy-weighted central point of cluster
4. Evaluate θ, φ of a central point
5. Compare with MC truth
θ ( φ ) resolution [rad] = θ ( φ ) meas – θ( φ ) MC
central point
γIP
(generated point)
ECAL
clustering
(θ,φ)
Clustering method
1. Find the highest energy deposit cell
2. Make the cone with a focus on it
3. Define cells which are inside of the cone as one cluster (around all layers)
4. Find energy-weighted central point
clustering angle = 10°γ@10GeV
IP (generated point)
highest energy deposit cellcentral
point
Position resolution of cluster (cell : 1 cm)
|cos(θ)| |cos(θ)|
σ [
mra
d]
σ [
mra
d]
barrel endcapendcap barrel
1 GeV2 GeV5 GeV
10 GeV
θ resolution is better for larger cos(θ)
φ resolution is worse for larger cos(θ)
IP (generated point)
ECAL geometrical effect
Position resolution : ~0.3 [cm]
Energy Dependent Result of position resolution
15.091.0
E
22.081.0
E
θ barrel :
θ endcap :
09.008.1
E
23.078.1
E
φ barrel :
φ endcap
:
[mrad]
[mrad]
[mrad]
[mrad]
1/√E 1/√E
σ [
mra
d]
σ [
mra
d]
10GeV
1GeV
2GeV
5GeV
Angular Resolution Study
direction of reconstructed gamma
IP (shot point)
1. Clustering
2. Find an energy-weighted central point of each layer
3. Fit each point with least-square method
4. Evaluate an angle between gamma-line and reconstructed gamma
Method (Angular resolution study of reconstructed gamma)
γ
reconstructed gamma
Calorimeter
anglepeakr peakr
Histogram and angular resolution
fitting function )12
exp(**02
2
p
xxp r histogram F(r)
σ = 48.3 ± 0.3 [mrad]
)(*)( rfrrF
)2
exp(*)(2
2
r
Arf
IP central point of cluster
r
d
r d
γ
reconstructed gamma
angle [rad] = r/d
gamma@10GeV
Energy dependence (1,2,5,10,50GeV)
Eangle
125 [mrad]
Average over full acceptance
1GeV2GeV
5GeV10GeV
50GeV
1/√E
σ [
mra
d]
Shoot from IP
Shoot from another point gamma@10GeV
IP
ECAL
Shoot from x=y=20, z=0
σ= 48.3±0.3[mrad]
IP
ECAL
σ= 48.6±0.3[mrad]
If gamma has been shot from another position, we could not observed significant
difference.
reconstructed gamma
Calorimeter Component Dependence
Structure (cell size dependence)
Absorbercell size
[cm]X0
Energy Resolution
W[3mm] 0.5~10 28 14.8%
gamma : E = 10GeV
How about cell size dependence?
Cell size dependence
1 [cm] : 48.3 ± 0.3 [mrad] 0.5 [cm] : 46.4 ± 0.3 [mrad]
gamma @10GeV
<5%
We could not observed significant improvement from 1cm to 0.5cm
Structure (energy dependence)
Absorbercell size
[cm]X0
Energy Resolution
W[3mm] 0.5~2 28 14.8%
gamma : E = 1~10GeV
How about energy dependence between 1cm and 0.5cm?
Energy dependence (1,2,5,10GeV)
1GeV
2GeV
5GeV
10GeV
No significant difference has been observed between 1cm and 0.5cm around all of energy.
Absorbercell size
[cm]X0
Energy Resolution
W [3mm] 0.5~2 28 14.8%
Pb [4.8mm] 0.5~2 28 15.0%
Pb [3mm] 0.5~2 22
Structure (Absorber dependence)gamma : E = 10GeV
How about absorber dependence?
Absorber dependence (Tungsten, Lead)
@1x1 [cm]
Lead[4.8mm]
Tungsten[3mm]
Tungsten [3mm] : 48.3 ± 0.3 [mrad] Lead [4.8mm] : 45.5 ± 0.3 [mrad]
Lead[3mm]
Same total radiation length
Angular resolution with Lead is better than Tungsten
Cause
depth depth
gamma MC
gamma MC
reconstructed gamma
reconstructed gamma
Angular resolution is better than Tungsten, since Lead has deeper distribution.
Average of gamma @10GeV
Angular Resolution Energy Resolution
Tungsten [3mm] 48.3 ± 0.3 [mrad] 14.8%
Lead [4.8mm] 45.5 ± 0.3 [mrad] 15.0%
Angular resolution of default-GLD Calorimeter (W:1cm)The angular resolution is estimated to be 125mrad/
√(E/GeV) Dependence on cell size granularity and materi
al dependence (W, Pb) has been studiedNo significant difference has been observed betwee
n 1cm and 0.5cmLead is better than Tungsten for isolated gammaEnergy resolution is sameHow about energy resolution for jet ? Next talk
Summary
Backup
θ, φ resolution study of cluster
1. Shoot single-gamma from IP with random direction
2. Clustering - use hit data from ECAL(,HCAL)
3. Search central point of cluster
4. Find θ, φ of a central point
5. Compare with MC truth
θ ( φ ) resolution [rad] = θ ( φ ) MC – θ( φ ) meas
IP
central point
γ
Clustering1. Find the highest energy deposit cell
2. Make a cone with centering around it
3. Define cells which are inside of a cone as one cluster
4. Find a central point by energy weighted mean
clustering angle = 10°γ@10GeV
IP
Judging by inner productIP
1cell ( 1cm x 1cm ) θ, φ
z=0 ( |cos(θ)|=0 ) max θ1cell
210c
m
IP
1cm1c
m
θ ( φ ) 1cell = 1/210 ≒ 4.7 [mrad]
z=280 ( |cos(θ)|=0.8 ) min θ1cell
IP
θ1cell ≒ 1.71 [mrad]
θ resolution (cell size : 1x1 cm)
φ resolution (cell size : 1x1 cm)
Result (θ, φ resolution) gamma@10GeV
• θ ,φ resolution
θbarrel : 0.430±0.004 [mrad] θendcap : 0.282±0.006 [mrad] φbarrel : 0.423±0.004 [mrad] φendcap : 0.699±0.014 [mrad]
θ1cell 1.71≒ ~ 4.70 [mrad]
Angular resolution is good as well as cell size (1x1cm)
1. Clustering
2. Find a central point of each layer by energy weighted mean
3. Fit each point with least-square method
4. Find an angle between IP and reconstructed line
Angular resolution study ofreconstructed line
IP
γ
reconstructed line
Fitting methodFind a central point of each layer by energy weighted mean
x
y
weighted by energy deposit
Fitting 2-dimentions (x-y)
y’
z
y’
Fitting new 2-dimentions (y’-z)
Distance[cm]
2-dimension normal distribution
)2
exp(*),(2
22
yx
Ayxf
)2
exp(*)(2
2
r
Arf
)(*)( rfrrF
peakr
r histogram F(r)
peakr
Distance (d) and angle
angle [rad] = d/r
)12
exp(**02
2
p
xxp fitting function
IP
central point of cluster
r
d r d
γ
reconstructed line
Linearity(1,2,5,10,50 GeV)
2x2 cm
1x1 cm
Linearity is kept below 10GeV.E
angle
125 [mrad]
Angular resolution Absorber (Tungsten, Lead)
@1x1 [cm]
Lead[4.8mm]
Tungsten[3mm]
Tungsten : 48.26 ± 0.29 [mrad] Lead : 45.51 ± 0.28 [mrad]
Lead[3mm]
Average (10000 events)
Hit cell number
Highest energy layer
Energy sum
Tungsten 252 5.7 0.412
Lead 284 5.6 0.429gamma @10GeV
Hitting distribution and Average
Hit cell numberLayer number of
central pointEnergy
Resolution
Tungsten 252 5.7 14.8%
Lead 284 5.6 15.0%gamma @10GeV
Fitting of Lead makes successfully than Tungsten, because Lead has deep distribution.
Fitting
0.068*x-14 0.031*x+6.8
Lrad [g/cm2] Lrad [cm] RM [cm]
Tungsten 6.96 0.699 0.71(?)
Lead 6.57 0.908 1.29(?)
Cause
Hit cell numberLayer number of
central pointEnergy
Resolution
Tungsten [3mm] 252 5.7 14.8%
Lead [4.8mm] 284 5.6 15.0%
Average of gamma @10GeV
depth (layer) depth (layer)
gamma MC
gamma MC
reconstructed gamma
reconstructed gamma
Since Lead has deeper distribution, angular resolution is better than Tungsten.