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Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects. Zdenek Vykydal Institute of Experimental and Applied Physics, Czech Technical University in Prague, Czech republic www. medipix .cvut.cz PhD seminar, Řež 26.9.2007. Outline.
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Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects Zdenek Vykydal Institute of Experimental and Applied Physics, Czech Technical University in Prague, Czech republic www.medipix.cvut.cz PhD seminar, Řež 26.9.2007
Outline • Introduction to the Medipix2 detector • Principles of detection with counting pixel detectors • Medipix2 single particle counting chip • USB Read-out interface for Medipix2 chip • RELAXd project • 3D interconnect technology • High density bumping • Through silicon via • ATLAS-Medipix project • Detector network structure • Background measurement in ATLAS cavern Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
Threshold level Principle of semiconductor single particle counting pixel detector • Threshold level above • electronic noise • No false counting. Digital integration (counting) • No dark current. Unlimited dynamic range and exposure time. Detected count obeys poissonian distribution N+ P+ + Si Bias Voltage Amplifier Pixelated front-side electrode Common back-side electrode Counter: Particle count Compa rator 000 001 Pixel electronics Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
Trigger Back-side pulse processing:Getting information about energy of interacting particle Bias Voltage E Preamplifier (charge sensitive) Multichannel analyzer Energy spectrum Count a (E) FWHM Detector chip E Energy [channel] Medipix-2 chip Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
Medipix2 detector:Single particle counting pixel detector www.cern.ch/medipix Medipix2 – MEDical Imaging PIXel detector 2nd generation • High spatial, high contrast resolving CMOS pixel read-out chip • Array of 256x256 pixels • Pixel size 55x55 mm² • Sensitive area of 14x14 mm² (87% of entire chip area) • Amplifier, two discriminators and a 13-bit counter in each pixel cell • Serial or parallel readout at 100MHz • Hybrid technology allows to use different semiconductor sensors Medipix2 Single Pixels: 256 x 256 Pixel size: 55 x 55 mm2 Area: 1.5 x 1.5 cm2 Medipix2 Quad Pixels: 512 x 512 Pixel size: 55 x 55 mm2 Area: 3 x 3 cm2 Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
Bias voltage noise distribution Back side pulse spectrum Combined alpha source: 241Am + 239Pu + 244Cm www.medipix.utef.cvut.cz USB1.1 interface:Realizationandgeneralfeatures • Serial readout speed: 4 fps (4 Mbits/s) • Camera-like size, plug and play, hot swap • Fully USB powered • Integrated source of variable detector bias voltage (5 – 100V) • Advanced triggering and hardware timer • No limit for cable length (various USB extender types) • Back-side pulse monitoring for spectroscopic applications and triggering • Open system architecture - internal analog and digital interface for "plug-in" PCB modules connection Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
USB Lite interface + Low power consumption (no external source) + Portability & flexibility — Performance limitations • First prototype ready and tested • Single chip 3-side tilable read-out assembly board • Based on USB 1.1 interface • Increased miniaturization • Dimensions: 15 mm x 60 mm Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
RELAXd project 2005 - 4 months @ NIKHEF, Netherlands 2006/2007 - 6 months @ IMEC, Belgium Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
RELAXd project www.nikhef.nl/pub/experiments/medipix RELAXd (High Resolution Large Area X-ray Detector) • Four-side tilable Medipix Quad modules • Serial readout of individual Medipix chip up to 500 MHz • Fast serial readout of whole Quad module up to 3.125 Gbps Used technologies: • 3D Integrated Electronic Microsystem • Edgeless sensor technology • 2D Pitch adaptation between sensor and readout ASIC • CMOS ASIC 200 mm wafer thinning • Through silicon vias made by deep reactive ion etching • BGA bumping instead of wire-bonding • High density Indium bump-bonding • Multi-Gbit/s data transmission to the PC Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
3D interconnect technology • The Medipix2 chip was designed as three-side tilable to enable the possibility of building detectors with larger sensitive area. Size of the I/O periphery and commonly used wire-bond technique for signal connection limits the tiling possibilities of the device to 2 row stripes. To overcome this limitation it is necessary to: • Increase the size of the sensor chip to cover I/O area • use pixels with size of about 65 x 65 µm2 and contacts redistribution (interposer layer or postprocessed metal wiring ) • use guardring-less sensor chip • Use another technology for connection of the I/O signals Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
High density Indium bumping • Process flow: • Under bump metallization (UBM) deposition and patterning at detector and Medipix2 substrate • In material deposition and patterning at detector and Medipix substrate • Flip-chip integration and reflow Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
Through silicon via technology • Newly developed technology to interconnect the front side and back side of the processed silicon wafer • Not application specific • Low temperature process (< 250 °C) • Via resistances in the range of 20 - 30 m (resistance of conventional wire-bond connection is about 60 m/mm for 25 µm wire) Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
ATLAS-Medipix project Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
ATLAS-Medipix project Main goal is measurement of the radiation field (especially neutron field) in ATLAS experiment Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
PC with Windows OS (up to 8 devices) PC with Windows OS (up to 8 devices) PC with Windows OS (up to 8 devices) Detector network structure 2 options: < 40 m ethernet cable < 60 m CERN LVDS cable Board with switches controlled by 7th USB port. If any of devices failed in any way it can be physically disconnected. 2U rack in cavern Power source 20V, 5A Power source 20V, 5A Power source 20V, 5A Rack in USA15 PC with 2 ethernet cards and Linux OS (large HDD for data storage) Ethernet switch 65m Public Ethernet (standard cable) Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
Connection options USB - extender Medipix USB interface USB USB extender USB extender Ethernet cable <40m with optional power wires (40V) Mounted in UX15 Detector USB interface LVDS Medipix Radhard LVDS LVDS cable 10 twisted-pairs (20 wires), plus power wires (4-6V), plus coax for BIAS. <60m Mounted in UX15 Detector • USB extender solution • Maximum length ~40m • Tested many times • Full capabilities of USB available (DAC feedback) • LVDS cable solution • No feedback (DAC out) – THL-FBK values will vary after irradiation, impossible to check • Working up to 60m but it needs software adaptation Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
ProtectiveBox Size of the box was chosed to accomodate both considered connection options 240 mm 25 mm 60 mm USB extender + optional 40V to 5V converter or LVDS converter instead of USB interface Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
First assemblies mounted in ATLAS cavern • 17.8.2007 - first two assemblies (MPX07 and MPX11) were mounted in ATLAS cavern • Remote controll (from the internet) of the devices was established and tested • Continuous data acquisition is running from 19.8.2007 measuring natural background in the ATLAS environment Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
MPX 07 device PE LiF PE + Al Al Uncovered MPX07 – Top of the TILECAL barel • Horizontal orientation • Fully opened window • Distance of 16m from UX15 • Easily reachable Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
MPX 11 device PE LiF PE + Al Al Uncovered MPX11 – cavern wall USA side • Vertical orientation • Protected with the black tape • Distance of 18m from the UX15 • Easily reachable Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects
Thanks a lot for your attention Medipix2-based radiation camera and it's application in RELAXd and ATLAS projects