Timepix2 power pulsing and future developments X. Llopart 17 th March 2011.
The Medipix3 and Timepix2 Chips
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[email protected] 1 [email protected] The Medipix3 and Timepix2 Chips Applications and Future Developments Richard Plackett, University of Glasgow VERTEX2010, Loch Lomond, 8 th June 2010 On behalf of the Medipix Collaboration and Xavier Llopart in particular
description
The Medipix3 and Timepix2 Chips. Applications and Future Developments Richard Plackett , University of Glasgow VERTEX2010, Loch Lomond, 8 th June 2010. On behalf of the Medipix Collaboration and Xavier Llopart in particular. Outline. Current Detectors – Medipix2 and Timepix - PowerPoint PPT Presentation
Transcript of The Medipix3 and Timepix2 Chips
[email protected] [email protected]
The Medipix3 and Timepix2 Chips
Applications and Future Developments
Richard Plackett, University of Glasgow VERTEX2010, Loch Lomond, 8th June 2010
On behalf of the Medipix Collaboration and Xavier Llopart in particular
Outline
Current Detectors – Medipix2 and Timepix• Chip Descriptions• Principles of Operation
Current Developments - Medipix3• Chip Description• Development Issues
Future Projects – Timepix2• Proposed Chip Designs and Ideas
Applications• Dosimitry, Education, Microscopy, Tracking,
Photon Detection, Medical Imaging
Two CollaborationsMedipix2
• INFN Cagliari• CEA-LIST Saclay• CERN Geneva• University of Erlangen • University of Freiburg • ESRF Grenoble • University of Glasgow• University of Houston • IFAE Barcelona • Mid Sweden University • MRC-LMB Cambridge • INFN Napoli • NIKHEF Amsterdam • INFN Pisa • FZU CAS Prague • IEAP CTU Prague • SSL Berkeley
Medipix3
• ALMOF Amsterdam• University of Bogota• University of Canterbury NZ• CEA-LIST Saclay • CERN Geneva• DESY Hamburg• Diamond Light Source• University of Erlangen• ESRF Grenoble• University of Freiburg • University of Glasgow• ITER • University of Karlsruhe• Leiden University• Mid Sweden University• NIKHEF Amsterdam • IEAP CTU Prague• SSL Berkeley• VTT Microsystems
21 collaborating institutes
The Medipix ChipsA philosophy of functionality
built into the pixel matrix allows complex behavior with a minimal inactive region
55um square pixel matrix 256 by 256
Configurable ‘shutter’ allows many different
applications
Silicon, 3D, CdTe, GaAs, Amorphous Silicon, Gas
Amplification, Microchannel Plates etc…
Development PathMedipix1 1um SCAMOS 64 by 64 pixels
Photon Counting Demonstrator (1997)
250nm IBM CMOS, 256 by 256 55um pixels Full photon counting (2002)
130nm IBM CMOSPhoton Counting, Spectroscopic, Charge Summing, Continuous Readout (2009)
Fast front end, Simultaneous ToT and ToA (2011)
Analogue (ToT) and Time Stamping (ToA) (2006)
130nm/90nm/65nmFuture LHCb readout – Data driven 40MHz ToT 12Gb/s per chip (2013)
Medipix2
Timepix
Medipix3
Timepix2
VELOpix
CLICpix130nm/90nm/65nmFuture Hybrid Pixel Time tagging layer for the LCD project (20??)
Medipix2 (2002) – Photon Counting
sensor
Analogue amplification
Digital processing
Chip read-out
1 1 123 2
Each hit in the sensor is converted into a count in the 13 bit counter
Noise and below threshold events are not counted at all
1000 electron noise floor
The shutter closes and the data are shifted out
Medipix2 Applications
• The most commercialized of the current chips and being sold by PANalytical (NL) in X-Ray Diffractometers
• Also active applications in– Material Analysis– Medical Imaging– Synchrotron Light Source Instrumentation– Micro CT material analysis– Proton Beam Monitoring (at the SPS)– Electron microscopy– Mass spectrometry– Neutron Imaging– Charged Particle Dosimitry
Timepix (2006)
sensor
Analogue amplification
Digital processing
Chip read-out
Timepix design requestedand funded by EUDET collaboration
Conventional Medipix2 counting mode remains.
Addition of a clock up to 100MHz allows two new modes.
Time over ThresholdTime of Arrival
Pixels can be individually programmed into one of these three modes
Time over Threshold
Threshold
Time Over Threshold counts to the falling edge of the pulse
Threshold
Time of Arrival
Time of Arrival counts to the end of the Shutter
Or As Results…Time of Arrival
Strontium SourceTime over Threshold
Ion Beams at HIMAC
Charge deposition studies with various Isotopes Space Dosimetry
Courtesy L. Pinsky, Univ. Houston
Timepix Applications• New Tracking Technologies
– LHCb Upgrade– CLIC detectors– Solid state Detector Development
• TPC instrumentation– EUDET
• Emission Channeling Crystal Lattice Experiments– ISOLDE
• Image Intensifiers / Optical Photon Detectors– Adaptive Optics– Bioimaging– LHCb RICH
• ToF Mass Spectrometry– Proteomic Imaging at AMOLF and Oxford
• Imaging Mass Spec– Functional Cellular Biology at Kiev
• Photo Electron Emission Microscopy and Low Energy Electron Micrsocopy• Neutron Monitoring at CNGS• Space Dosimintry• Education - CERN@School
As yet no one has sold any Timepix products, but lots of Interesting science is being done with them
LHCb Testbeam
6 pixel telescope planes angled in 2 dimensions to optimise resolution
Device Under Testmoved and rotated viaremote controlled stepper motor
Fine pitch strip detectorwith fast electronics readout
ATLAS Neutron Dosimitry
LiF (50 µm) used for thermal
neutrons detection
Uncovered accepts all particles
low sensibility to neutrons
PE (1.3 mm) used for
fast neutrons detection
PE + Alused for fast
neutrons detection
removing low energy
electron photons contributions
Al (50 and 100 µm)
used to stop low energy electrons
and photons
J. Jakubek, S. Pospisil, M. Suk, D. Turecek and Z. Vykydal and the Group at Prague CTU
CERN@ School / LUCID
• Langton Ultimate Cosmic-ray Intensity Detector– A space based directional cosmic ray experiment– Operated by Simon Langton Grammar School (Kent)– Joint project with CERN and SSTL– Launch 2011….
• CERN@School– Timepix chips in classrooms as ground based wide area cosmic ray
detectors– Also excellent teaching aids for radioactivity– Possibility of loaning systems to schools – Feasible to construct remotely operated systems to log into
As a Teaching Aid – Americium Source
No filter, alpha particles and photonsTape filter, only photonsHalf covered shows the difference
Low Energy Electron Microscopy
Images of Graphene Flakes presented to the Medipix2 collaboration by I. Sikharulidze, Leiden
‘Medipix2 applied to low energy electron microscopy’, Ultramicroscopy 110 (2009) 33 - 35
MCP + CCD imagesMedipix2 Images
Photon Detectors
Glasgow HPD
Berkeley MCP phototube
Medipix2 Funded Quad Phototube
Four Timepix in a square phototube
Collaboration between:BerkeleyCERN
ErlangenGlasgowNikhef
Many applicationsWith VELOpix even LHCb RICH upgrade possbilities
UA9 - Crystal Beam Channeling for sLHC
Data and analysis by L. Tlustos on behalf of the UA9 collaboration
Medipix3 (2009)
17.3
mm
14.1 mm
• Increased pixel to pixel communication• Several advantages over Medipix2
• Charge summing mode – prevents spectral distortion due to
charge sharing• Spectroscopic mode
– four pixels to sharing thresholds and counters
• Two counters per pixel – allowing continuous shutter based
readout• Increased Radiation Tolerance
– From 130nm CMOS process
Medipix3 Modes
Pixel Operation Modes Pixel size # ThresholdsSingle Pixel
Fine Pitch Mode → 55 µm x 55 µm 2Charge Summing
Colour ModeSpectroscopic Mode → 110 µm x 110 µm 8
Colour Mode with charge Summing
Pixel Gain Modes Linearity # ThresholdsHigh Gain Mode ~10 ke-
2Low Gain Mode ~20 ke-
Pixel Counter Modes Dynamic range # Counters1-bit 1 2
4-bit 15 2
12-bit 4095 2
24-bit 16777215 1
Pixel Readout Modes # Active Counters Dead TimeSequential Count-Read (SCR) 2 Yes
Continuous Count-Read (CCR) 1 No
Medipix3 Charge Summing Mode
sensor
Analogue amplification
e-h+
Digital processing
Chip read-out
10001110101
A hit in the sensor deposits charge
The charge passes to the analogue amplifiers
The Medipix 3 charge summing circuit operates
The counter is iterated and read out with the shutter
Medipix3 Charge Summing Mode
10001110101
A hit in the sensor deposits charge across four pixels
The analogue comparators assign the charge to the pixel with the most hits
This prevents ‘lost’ charge by partial hits not passing threshold
The threshold is applied to the summed charge and read out when the shutter closes
Medipix3 can be configured to sum charge across four pixel clusters to prevent hits being lost due to charge sharing
Charge Summing
Charge sharing events produce a low energy smearing of the landau
Initial Measurements of Medipix3 indicate the charge summing circuitry works as expected
Single pixel mode
Charge Summing Mode
Measurement by L.Tlustos and R. Ballabriga CERN
Spectroscopic (Colour) Mode• By connecting 4 pixels into a larger super pixel, eight threshold levels are
available to us in the digital part of the pixel…
Counter 1
Counter 2
Counter 3
Counter 4
Counter 5
Counter 6
Counter 7
Counter 8
Amplifier response
• Each threshold is adjustable, allowing a wide range of settings.
• This gives us enough flexibility to capture reasonable spectra in many different applications
Medipix3 Radiation Hardness• 130nm CMOS was expected to be very
tolerant to integrated dose from test chip measurements
• So far Medipix3 has been tested with an X-Ray flux up to 500MRad and has remained operational
0 15 30 45 60 75 90 105 120 135 1500
1000
2000
3000
4000
5000Pixel Non-IrradiatedPixel Irradiated at 460 MRad
THL [DAC step]
Pixe
l cou
nts
0 100 20040
60
80
100
Row Number
Noi
se [e
-]
460MRad
400MRad Noise Floor
Signal
Medipix3 Matching Problems
• One of the major debugging efforts in Medipix3 is a larger than expected pixel to pixel threshold variation
• Especially obvious in charge summing mode• Design team in close contact with IBM to solve matching Issues
Can Still take Beautiful Images
Image of a leaf with Fe55 source930 e- minimum threshold
Courtesy of R. Ballabriga - CERN
Medipix3 Applications
• Multi-Energy CT – Spectroscopic Imaging mode
• SLS instrumentation– Radiation tolerance and continuous readout
• High Z Sensor Development (see David’s talk)– Charge summing to produce correct landaus
• Beam Monitoring– Radiation Tolerance
• Irradiated Sensor Development– Radiation Tolerance
Timepix2 Proposals (2013?)
• Timepix2 Design is still in flux• Simultaneous ToT and ToA • Sub 25ns rise time• Fast fine timing ~1ns
• Many ideas for the remaining details• Possible data driven scheme akin to VELOpix allowing high
readout rates and continuous sensitivity• Small pixels with highly configurable interconnects in an
FPGA-like design• Shutter? Trigger? Frame based? Sparse Readout?
Data Driven Timepix2
• The ‘ideal’ detector will read out all hits…• An attempt to get close to this is the ‘Data Driven’ design• Will push all events off the chip up to a limiting event rate
• Good for low rate and sparse applications• Problematic for SLS physics or high rate imaging• Cannot use the shutter to ‘squeeze down’ data rates
• Closer to ideal but not useable for all applications• Requires significant on matrix logic and readout infrastructure
to achieve high data rates
A Data Driven Timepix2 (VELOpix)• Limited to sparse readout • Super pixel architecture to compress clustered data on matrix• Very high maximum data rate
Digital readoutAnalog DACs
A multi pixel cluster can be read out much more efficiently in a super pixel architecture
However this is quite a strongly optimised design, possibly not ideal for all applications
220um
An FPGA-Like Timepix2
• Small (27.5um) pixels, each with a clock, threshold and counter could be combined in a reconfigurable way
Amplifier
55um
DiscriminatorToT / ToA / Count
Counter / Memory
Amplifier
DiscriminatorToT / ToA / Count
Counter / Memory
Amplifier
DiscriminatorToT / ToA / Count
Counter / Memory
Amplifier
DiscriminatorToT / ToA / Count
Counter / Memory
A pixel that can measure ToT and ToA simultaneously, with deep counters
A large area Timing pixel with a very deep counter
High resolution ToT pixels for tracking
Not Necessarily Technically Feasible
Concept by J. JakubekPrague CTU
Timepix2 Possible Applications
• Particle Tracking – LHCb, LCD interest• Molecular ToF spectrometry• TPC readouts• Neutron Dosimitry• Double Beta Decay & Neutrino Capture Experiments• …
To Conclude
• Medipix2 and Timepix have been successful so far and built a large ecosystem of applications.
• Medipix3 shows promise, initial verification complete and working with IBM to solve remaining problems.
• Timpix2 is being designed/specified at the moment with a robust discussion about the required performance and how to achieve it.
Chip Noise Details
• Medipix2 noise floor 1000 electrons• Timepix 650 electrons• Medipix3 75 electrons
Timepix (2006)
• An evolution of the Medipix2 chip• Similar architecture replacing a discriminator level with
100MHz clock signal and three operating modes
• Each pixel is individually programmable into one mode– Time of Arrival – Time Tagging– Time over Threshold – Analogue Hit Information– Medipix - Hit Counting
Timepix Modes of Operation
Threshold
• ToT and ToA modes make use of the timepix clock to record the time between passing threshold and another event
• Time Over Threshold counts to the falling edge of the pulse• Time of Arrival counts to the end of the Shutter
Medipix2 – Details• 256 by 256, 55um square pixels• Pixel columns read out as shift registers
when shutter closes• ~1.5ms minimum full matrix readout• Noise floor ~1000e-• 3 bit threshold trim
16.1
mm
14.1 mm
A Medipix2 wafer undergoing QA wafer probing
