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FBK 3D CMS pixel sensors
preliminary lab measurements
E. Alagoz1, A. Krzywda1, D. Bortoletto1, I. Shipsey1, G. Bolla1, and G. F. Dalla Betta2,
M. Boscardin3, S. Kwan4
1Physics
Department, Purdue University, West Lafayette, IN 47907-2036 USA
2NFN and University of Trento
3FBK, Via S. Croce 77 - 38122 Trento – Italy
4Fermilab, Batavia, IL 60510-5011 USA
CMS Tracker Upgrade Plenary, 22 July 2011
Outline
• 3D vs planar
• FBK 3D pixel sensors for CMS
– Readout chip (ROC) characterization tests
– Noise tests
– Charge collection tests
• FBK 3D pixel sensors testbeam plans at FNAL
• Summary and outlook
3D vs planar
• p+ and n+ electrodes are arrays of columns that penetrate into the bulk
• Lateral depletion
• Charge collection is sideways
• Superior radiation hardness due to smaller electrode spacing:
- smaller carrier drift distance
- faster charge collection
- less carrier trapping
- lower depletion voltage
• Higher noise
• Complex, non-standard processing
depletion
ionizing particle
PLANAR:
n+
depletion
p+
3D:
n+
e
300µm
p-type
p-type
h
p+
50µm
FBK 3D sensors
• FBK processed full 3D sensors for CMS
• Sensors with guard rings
• Three geometries: 1E,2E,4E
• 14 sensors per wafer
• Thickness 200 microns
• Sensors received from
ATLAS 08 batch
CMS
1E
1E
2E
1E
2E
1E_3
1E
1E_4
2E
2E_11
1E
4E
1E
4E
1E_6
1E
1E
4E
FBK 3D sensors
• Sensors bump bonded to PSI46v2 ROC in SELEX (In bumps)
• 9 sensors received in 2011: 1E (6x), 2E (1x), 4E (2x)
• Wire bonded and assembled on FPIX plaquettes
• PSI test setup is used to fully calibrate FBK sensors in lab
• ROC calibration
• Noise
• Charge collection with Sr-90 source
Purdue setup for 3D testing
FBK sensor plaquette
IV measurements
Lab tests @ V = -5 V : T=21 °C
A sample summary
report of a psi46v2 ROC
calibration
Noise tests T=21 °C
Single pixel noise curve
Noise distribution
Error function
fit
Gaussian fit
Noise map
Higher noise due to
long pixel on the
sensor edges
Noise scans @ T=21
°C
4E
2E
1E
Charge collection tests @ T=21
°C • Sr-90 source: 1 mCi, Eβ = 0.546 ΜeV
• Random trigger used
Landau convoluted Gaussian fit
1 Vcal = 65 eMP = 14 ke-
Charge collection scans @ T=21
°C
• FBK_4E_13 has relatively lower charge collection
• Gain calibration is problematic
Summary & outlook
• All 9 sensors were wire bonded and assembled at Purdue
Lab characterization tests:
• IV results: breakdown at Vbias < 40 V
• Performed well with noises compatible with CMS planar pixels
• Good bump bond quality
• Charge collection with Sr-90 source for all sensors
– 1E_3 sensor has irregular charge distributions at Vbias > 25 V
• ROC calibration needs to be optimized
Testbeam plans:
• Testbeam at FNAL in October 2011
• Irradiation will be soon after the testbeam
• Post-irradiation testbeam at FNAL in February 2012
3DC
Czech Technical
University, Fermilab,
Purdue University,
SINTEF, SLAC, University
of Hawaii, University of
Manchester
BACK UP SLIDES
FNAL testbeam
SCINTILLATORS
DUT
PIXEL DETECTORS
ACELLERATOR
CLOCK
• 120 GeV protons
• No B field
BEAM
Meson Area
Purdue 3D plaquette
Plastic
protection
CLOCK AND
TRIGGER
DISTRIBUTION
3.7V POWER
SUPPLY
Cooling
tubes
CONTROL ROOM