Introduction Measurements Simulations Summary
Test of 3D Silicon pixel detectors:
Simulation and measurements
Kyrre Ness Sjøbæk
University of Oslo / ATLAS 3D Pixel R&D Collaboration
Spåtind 2010, Nordic Conference in Particle Physics
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Test of 3DSi pixel detectors
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Introduction Measurements Simulations Summary
Outline
1
Introduction
3D Pixel Detectors
Testbeam Characterization
2
Experimental Results
Tracking Efficiency
Charge Sharing
Position Resolution
3
Simulations
Track Resolution
Beam Telescope Model
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Test of 3DSi pixel detectors
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Introduction Measurements Simulations Summary
3D Pixel Detectors Testbeam Characterization
Pixel detectors
• Used for tracking/vertexing
in high-intensity
environments, such as the
ATLAS innermost layers
• Crucial for identifying
B-jets and other short-lived
particles
• Detectors in ATLAS inner
layer has to withstand a
radiation dose in excess of
1015 cm−2 1 MeV neutron
equivalents
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Introduction Measurements Simulations Summary
3D Pixel Detectors Testbeam Characterization
ATLAS Pixel Inserted B-Layer (IBL)
• Project to place an extra
layer of pixel sensors
inside current ATLAS
B-layer
• ≈ 3.2 cm from
interaction point ⇒ High
demands on radiation
hardness
• Plan is to install during
shutdown around 2015
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Test of 3DSi pixel detectors
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Introduction Measurements Simulations Summary
3D Pixel Detectors Testbeam Characterization
3D Silicon pixel detectors
• Novel tracking sensors
fabricated with MEMS
technology
• Electrodes are vertical
columns going through the
sensor bulk
Full 3D
• Shorter charge collection
distance ⇒ Less charge loss
in irradiated detectors
• No need for guard rings ⇒
Elimination of loss of
efficiency at edge
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Double side Double-Type
Column (DDTC)
Test of 3DSi pixel detectors
Spåtind 2010
5 / 18
Introduction Measurements Simulations Summary
3D Pixel Detectors Testbeam Characterization
Testbeam – SPS H8 May 2009 setup
Morpurgo magnet
~ 1.6 T
Devices under test
(DUTs) in
cooling box
Trigger scintillators
BAT telescope
for tracking
CERN North Area SPS target hall, H8 beamline, 180 GeV pions
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Test of 3DSi pixel detectors
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Introduction Measurements Simulations Summary
3D Pixel Detectors Testbeam Characterization
Testbeam – SPS H8 May 2009 setup
• Tracking using the Bonn Atlas
Telescope (BAT)
• Four pixel devices under test
(DUT’s):
• Planar device, standard ATLAS
type
• Stanford full 3D with active edge,
three electrodes
• Two FBK-irst sensors, Double
sided Double Type Column
(DDTC) (non-penetrating holes
etched from two sides)
• 1.6 T Morpurgo magnet used to
measure sensor response in
magnetic field
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Test of 3DSi pixel detectors
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Introduction Measurements Simulations Summary
Efficiency Charge Sharing Position Resolution
◦
Hit efficiencies at 0 , B = 0
Planar sensor, eff = 99.9%
Mask detail for Full 3D sensors with 3 electrodes
Stanford Full 3D, eff = 96.7%
FBK DDTC, eff = 99.2%
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Introduction Measurements Simulations Summary
Efficiency Charge Sharing Position Resolution
◦
Hit efficiencies at ≈ 15 , B≈ 1.6 T
Planar sensor, eff = 100.0%
Mask detail for 3D sensors with 3 electrodes
Stanford Full 3D, eff = 99.9%
FBK DDTC, eff = 99.8%
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Test of 3DSi pixel detectors
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Introduction Measurements Simulations Summary
Efficiency Charge Sharing Position Resolution
Charge sharing
Planar sensor, magnet off, angle = 0◦
Stanford Full 3D, magnet off, angle = 0◦
Planar sensor, magnet on, angle ≈ 15◦
Stanford full-3d, magnet on, angle ≈ 15◦
Non-perpendicular track ⇒ Charge sharing
⇒ Good position resolution
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Test of 3DSi pixel detectors
Spåtind 2010
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Introduction Measurements Simulations Summary
Efficiency Charge Sharing Position Resolution
Position resolution
Planar:
Stanford:
FBK:
0◦
≈ 15◦
RMS around 10µm for both planar and 3D devices
under IBL conditions
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Test of 3DSi pixel detectors
Spåtind 2010
11 / 18
Introduction Measurements Simulations Summary
Track resolution BAT model
Testbeam simulation
• Better understanding of the tracking setup
• Track resolution in the devices under test
• Effects of sensor (mis-)alignment
• Testbed for sensor models
Geometry + particle/matter interaction
+ device physics/electronics
should yield plots that are comparable to real data
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Test of 3DSi pixel detectors
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12 / 18
Introduction Measurements Simulations Summary
Track resolution BAT model
Overview of the testbeam simulation framework
DAQ
Hardware
Tracking
and
allignment
Energy depositions
dE, position
Geant 4
Simulation
Analysis
framework
Simulation of
Trigger &
digitalization
Simulation and data-taking
soon fully integrated
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Test of 3DSi pixel detectors
Spåtind 2010
13 / 18
Introduction Measurements Simulations Summary
Track resolution BAT model
Simulated SPS H8 setup
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Test of 3DSi pixel detectors
Spåtind 2010
14 / 18
Introduction Measurements Simulations Summary
Track resolution BAT model
Simulated residuals in device planes
5 µm smearing:
No smearing of hit:
h_yResDUT3
Y residual in DUT 3
Entries
Mean
500
RMS
χ 2 / ndf
Constant
400
Mean
Sigma
h_yResDUT3
Y residual in DUT 3
4758
Entries
-2.214e-05
Mean
4758
-1.333e-05
0.004701
418.8 / 92
RMS
250
χ 2 / ndf
445 ± 9.5
-2.169e-05 ± 3.505e-05
0.002281 ± 0.000034
Constant
200
Mean
300
Sigma
0.005502
264.3 / 91
264 ± 5.4
-2.329e-05 ± 6.010e-05
0.003984 ± 0.000054
150
200
100
100
0
-0.03
50
-0.02
-0.01
0
0.01
0.02
0.03
trackPosition - hitPosition [mm]
0
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
trackPosition - hitPosition [mm]
2.3[um] < Track resolution in DUT < 4.0[um]
Compatible with measurements using two planes for tracking into
third plane, and toy MonteCarlo model.
Full reconstruction chain from simulation not working right now,
using charge-weighted mean as hit position
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Test of 3DSi pixel detectors
Spåtind 2010
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Introduction Measurements Simulations Summary
Track resolution BAT model
BAT beam telescope – device model
• Start from localized
energy depositions from
Geant4
• Each energy deposition
creates a localized
charge-cloud
QL
x0
QR
x
• For each cloud:
Calculate simultaneous
drift/diffusion ⇒ Get the
charge deposited on six
closest strips
• Simulate electronics
readout
Kyrre Ness Sjøbæk
ξ
0
C(x,t’)
Result:
Realistic charge sharing,
BAT digits
Test of 3DSi pixel detectors
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Introduction Measurements Simulations Summary
Track resolution BAT model
BAT beam telescope – device model – η-distributions
Real data:
Simulation:
BAT_1_eta_p
Entries
11062
Mean
0.5026
RMS
0.3705
BAT1 p-side eta distribution
500
BAT_1_eta_p
Entries
36076
Mean
0.4996
RMS
0.3656
BAT1 p-side eta distribution
1400
1200
400
1000
300
800
600
200
400
100
200
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
η=
0.8
0.9
1
Eta
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Eta
QL
(6= pseudorapidity)
QL + QR
is a measure of charge sharing between two adjacent strips.
Charge-sharing in BAT planes are reasonably well described
Kyrre Ness Sjøbæk
Test of 3DSi pixel detectors
Spåtind 2010
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Introduction Measurements Simulations Summary
Summary
• New technology for radiation-hard tracking sensors
• Efficient and good position resolution in ATLAS IBL
conditions
• Simulation useful to better understand the testbeam
measurements
• Outlook
• Angle-scan
• Integration of simulation with reconstruction and analysis
software
• Real models for pixel devices
Kyrre Ness Sjøbæk
Test of 3DSi pixel detectors
Spåtind 2010
18 / 18
Backup
BACKUP SLIDES
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Test of 3DSi pixel detectors
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19 / 18
Backup
C. Da Viá et al., “Radiation hardness properties of full-3D active
edge silicon sensors” (2008)
3 yr LHC luminocity ⇒≈ 1015 [cm−2 ] 1 MeV neutron equiv. at
B-layer
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Test of 3DSi pixel detectors
Spåtind 2010
20 / 18
Backup
Cluster charge
Planar:
Stanford Full 3D:
B=OFF
0.2
B=OFF
0.2
B=ON
0.18
0.16
0.16
0.14
0.14
0.12
0.12
0.1
0.1
0.08
0.08
0.06
0.06
0.04
0.04
0.02
0.02
0
0
10000
20000
30000
40000
B=ON
0.18
0
0
50000
60000
70000
Cluster charge[e-]
0◦
10000
20000
30000
40000
B=OFF
0.2
B=OFF
0.2
B=ON
0.18
0.16
0.14
0.14
0.12
0.12
0.1
0.1
0.08
0.08
0.06
0.06
0.04
0.04
0.02
B=ON
0.18
0.16
0
0
50000
60000
70000
Cluster charge[e-]
≈ 15◦
0.02
10000
20000
30000
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40000
50000
60000
70000
Cluster charge[e-]
0
0
10000
20000
Test of 3DSi pixel detectors
30000
40000
50000
60000
70000
Cluster charge[e-]
Spåtind 2010
21 / 18
Backup
◦
Hit efficiencies at 0 , B≈ 1.6 T
row position [um]
Planar sensor, eff = 100.0%
column position [um]
Mask detail for 3D sensors with 3 electrodes
row position [um]
Stanford Full 3D, eff = 96.5%
column position [um]
row position [um]
FBK DDTC, eff = 99.1%
column position [um]
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Test of 3DSi pixel detectors
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22 / 18
Backup
η-corrections
BAT_1_eta_p
Entries
36076
Mean
0.4996
RMS
0.3656
BAT1 p-side eta distribution
1400
• Assume a flat distribution of
dN
dx
incoming particles
=
N0
∆
• Assume the charge is
1200
1000
800
distributed over two strips
600
400
• Measure the dN
dη -distribution,
where η is defined as
L
, and N0 is a
η = QLQ+Q
R
normalization constant
200
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Eta
0.6
0.7
0.8
0.9
1
Eta
BAT1 p-side eta distribution CDF
1
0.8
• By integration, the track
0.6
position is given as
0.4
∆
x (η) =
N0
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Z η
dN
0
dη 0
dη 0 +x (η = 0)
0.2
0
0
0.1
Test of 3DSi pixel detectors
0.2
0.3
0.4
0.5
Spåtind 2010
23 / 18
Backup
Definition charge-weighted mean (as used in track
residuals)
• Geant4 simulation provides
Sigma of hit spread (y) (Clustered & trigged) in BAT2
Counts
a set of sensor-local (x , y , z)
of hit positions / energy
deposition
h_hitposLocal_sigma_clustered_trigged_y_BAT2
Entries
8857
Mean 2.278e-05
RMS
3.378e-05
800
700
600
500
• Use this data directly to
provide an (x , y ) hit position
in the sensor plane, defined
as
P
qi xi
x̂ ≡ Pi
i
qi
400
300
200
100
0.02
0.04
(equiv. for y)
• Not using simulated device
×10
0.18 0.2
[mm]
-3
0
0
0.06
0.08
0.1
qP
σx ≡
i
0.12
0.14
0.16
qi2 (xi − x̂ )2
P
i
qi
response
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Test of 3DSi pixel detectors
Spåtind 2010
24 / 18
Backup
Definition hit efficiency
eff ≡
Number of tracks through center region of sensor w/ matching hit
Number of tracks through center region of sensor
• Matching hit: Hit within 1200 × 250µm from track (3 × 5
pixels )
• Cuts: χ2 for tracks, masked pixels (noisy pixels)
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Test of 3DSi pixel detectors
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