ERDIT EUROPEAN RADIATION DETECTION AND IMAGING TECHNOLOGY PLATFORM. Prof. Christer Fröjdh, Mid Sweden University

ERDIT EUROPEAN RADIATION DETECTION AND IMAGING TECHNOLOGY PLATFORM Prof. Christer Fröjdh, Mid Sweden University

OBJECTIVES Advanced radiation detectors require technology development in several areas Microelectronics Sensor materials Hybridization Production volumes are generally too small to motivate these developments Joining forces between different applications will help to generate a critical mass Applications show similarities but also differences

EUROPEAN RADIATION DETECTION AND IMAGING PLATFORM (ERDIT) The mission of the European Radiation Detection and Imaging Technology Platform is to promote the research on radiation detectors and imaging at European level. The aim of this platform is to synergistically implement a common research strategy across research infrastructures involving research laboratories, academy and industry which would benefit fundamental science, promote innovation in industry and would feed into the crucial European societal challenges. This would be implemented through a process of guidance, prioritization and promotion of research, innovation and education with respects to fundamental science principles and contemporary benefit to society and growth of global competitiveness of European industries.

EUROPEAN RADIATION DETECTION AND IMAGING PLATFORM (ERDIT) Collect information on important challenges for the development of high performance radiation detectors Collect information on the shortcomings of the current detectors as seen by the applications Work on common strategies for research and development in Europe. Develop technology roadmaps for radiation detector development Raise the awareness of the needs for radiation detectors and their impact on societal challenges Promote the field of research, education, innovation and knowledge transfer at national and European level

WHAT SHOULD THE PLATFORM COVER? Technologies Sensor materials Readout electronics Hybridization Packaging Data communication Data processing Future and emerging technologies Applications Astronomy Beam Monitoring Electron Cryo-microscopy Fusion Facilities Hadron Therapy High Energy Physics Medical Imaging Neutron Sources Nuclear Physics Environmental Monitoring Synchrotron Applications

ERDIT ACTIVITIES The website erdit.eu Network meetings ERDIT in Pisa April 2015, 13th-14th of April ERDIT in Stockholm 6 th - 7 th October 2014 ERDIT in Freiburg 7 th - 8 th April 2013 ERDIT at IAEA - Vienna 30 th Sept. - 1 st Oct. 2013 Kickoff meeting at CERN 11 th April 2013 Next meeting ERDIT in Athens April 2016

ERDIT ACTIVITIES National networks Sweden, Greece, Germany, Italy, UK, Norway, France, Hungary COST proposal Proposal submitted on March 24, 2015 WP1/WG1 Application requirements and standardisation WP2/WG2 Technology Roadmap Simulation of radiation detection systems Readout electronics Sensor materials and processing Hybridisation and mounting Packaging and system integration WP3/WG3 Future and emerging technologies WP4/WG4 Dissemination and training Evaluation results expected on October 30.

BASIC DETECTION PRINCIPLES

GAS FILLED DETECTORS A particle that passes through the gas will create ions along the track Ionisation chamber No gain, signal proportional to deposited energy Proportional counter Gain via gas multiplication, signal proportional to deposited energy Geiger counter Complete ionisation of the gas, no information on deposited energy - + - + + - + -

PIXEL DETECTORS WITH GEM Gas gain grids as GEM and TPC are used with pixel detector readout electronics for X-ray imaging Around 30 000 charges/mev TwinGrid: A wafer post-processed multistage Micro Patterned Gaseous Detector, Y. Bilevych, V.M. Blanco Carballo, M. Chefdeville, M. Fransen, H. van der Graaf, C. Salm, J. Schmitz, J. Timmermans, NIM-A, V 610, N 3, 2009

SOLID STATE DETECTORS Semiconductors Radiation interactions release electron hole pairs that generate a pulse or a current Scintillators Radiation interactions generate light that can be collected by a photodiode or a photomultiplier

CHARGED PARTICLES Protons Alpha particles Ions Fission fragments Electrons Generate charge tracks in sensor materials: The Bragg peak Characterised by: Mass Charge Energy

DETECTORS FOR CHARGED PARTICLES The particle leaves a charge track as it passes through the detector If the particle is completely stopped then the energy can be measured

THE BRAGG PEAK Energy deposition in a pixel detector

THE INTEGRATED DE/E DETECTOR The de/e detector can measure both mass and energy of a charged particle. Our process is based on wafer bonding with a buried metal

ELECTRONS Simulation of 300 kev electrons in Silicon The tracks cover several hundred microns Substantial backscattering

APPLICATION: RADON MEASUREMENTS

THE RADON DECAY CHAIN

THE MEASUREMENT SETUP

Bq RADON LEVEL AS A FUNCTION OF TIME 400 350 300 250 200 150 A103 A115 A117 100 50 0 0 20 40 60 80 100 120 140 160 180 200 Time (h)

NEUTRONS

NEUTRONS Stopped by certain materials. Secondary particles detected 3 He + n -> 3 H + 1 H + 0.764 MeV 6 Li + n -> 4 He + 3 H + 4.79 MeV 10 B + n -> 7 Li + 4 H + 2.31 MeV + g(0.48 MeV) -> 7 Li + 4 H + 2.79 MeV

NEUTRON DETECTORS A converter layer stops the neutrons and releases charged particles These particles are then detected by a semiconductor detector The converter must be thin enough to allow the secondary particles to pass into the detector

STRUCTURED NEUTRON DETECTOR

PHOTONS

PHOTON INTERACTIONS Photons interact by: Photoelectric absorption Compton Scattering Pair production > 1 MeV Stopping in a material is proportional to the electron density Heavy atoms needed The photon is either stopped or passes through the detector unnoticed

SEMICONDUCTOR OR SCINTILLATOR In a scintillator the light is emitted in all directions Losses at walls Limited spatial resolution Scintillators can be made in large volumes In a semiconductor the electric field directs the charge to the nearest contact Requires very pure materials to get full depletion Scintillator Semiconductor Contact

PHOTON INTERACTIONS Photoelectric Compton Electron Fluorescence photon Compton Electron Scattered photon Photoelectric absorption and Compton scattering gives the same signal unless any of the reaction products escape the detector

SENSOR MATERIALS Name Atomic Bandgap number (ev) Density Abs. 100 KeV in 0.5 mm Fluroescence length (um) Si 14 1.12 2.33 2% 12 Ge 32 0.67 5.32 14% 50 GaAs 31,33 1.42 5.33 14% 40 CdTe 48,52 1.44 5.85 39% 112 TlBr 81,35 2.7 7.56 79% 621

Absorption STOPPING IN 0.5 MM LAYERS 1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 0 50 100 150 KeV Si GaAs CdTe

SCINTILLATOR BASED DETECTORS A scintillator converts deposited energy to light. Important properties Stopping power Light yield Emission wavelength Refractive index The light from the scintillator is typically recorded using a photodiode or a photomultiplier Material Density (g/cm 3 ) Refract. index Peak emission (nm) Photons per MeV CsI (Tl) 4.51 1.78 550 60 000 GADOX (Eu) 7.5? 630 22 400 (Gd 2 O 2 S) YAG (Ce) 4.55 1.82 550 16 000 (Y 3 Al 5 O 12 ) CWO (CdWO 4 ) 7.9 2.25 470-540 18 000 BGO (Bi(GeO 4 ) 3 ) 7.13 2.15 480 8 500 ZWO 7.62 2.32 490 (ZnWO 4 ) LSO 7.42 1.82 420 (LuSiO 5 ) LuAG (Ce) 6.71? 510 (Lu 3 Al 5 O 12 ) * estimated value Si = 277 000 charges/mev

STRUCTURED SCINTILLATORS Structured scintillators can improve the spatial resolution Columnar CsI The scintillating guides screen Recent advances in columnar CsI(Tl) scintillator screens Stuart R. Miller ; Valeriy Gaysinskiy ; Irina Shestakova ; Vivek V. Nagarkar Proc. SPIE 5923, (September 16, 2005)

APPLICATIONS FOR RADIATION DETECTORS

SOME APPLICATIONS High energy physics Fast timing Tracking Radiation hardness Material budget Synchrotron applications High fluxes Fast readout Area Spectral resolution Spatial resolution Medical imaging Quantum efficiency Large area Industrial applications High energies Security High selectivity Environmental conditions Neutron imaging Special sensor materials High selectivity

SYNCHROTRONS

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TIMING

DYNAMIC RANGE Example from X-ray diffraction where weak spots could be located close to extremely bright spots

MEDICAL IMAGING

MEDICAL IMAGING Quantum efficiency!!! Spectroscopy is probably the next trend CT High flux many Mcps/mm 2 High speed rotation times less than 1 s Stability Imaging Large area up to 43 x 43 cm 2

Absorption X-RAY ATTENUATION IN A 500 UM THICK LAYER OF SOME SEMICONDUCTORS 1 0,8 0,6 0,4 0,2 Si GaAs CdTe 0 0 20 40 60 80 100 KeV 2015-10-23 42

FROM DENTAL TO FULL CHEST IMAGING

SPECTRAL IMAGING Different contrast agents in one image Separate bone and contrast agent. N. G. Anderson et.al.spectroscopic (multi-energy) CT distinguishes iodine and barium contrast material in MICE, Computed Tomography, 2009

SPECTROSCOPIC COLOUR IMAGING Iodine: Pulmonary circulation Barium: Lung Bone: normal structure Courtesy: A. Butler

SECURITY

THE PROBLEM To monitor radiation levels in an area and to send an alarm in case of suspected security risks The system should be energy sensitive and selective between gammas, neutrons and charged particles The system should be sensitive to levels slightly above the natural background The system should be able to distinguish between Variations in natural background Variations due to legal sources Variations due illegal sources, accidents or nuclear attacks 2015-10-23

MOBILE RADIATION SURVEILLANCE GPS Gamma Sensor data Group Management Presence Operator X Operator Y INTERNET SBG 3G IMS Application Server GPS H 2 O Acc Google Earth CO 2 2015-10-23 Sensors in Google Earth / Maps Sensor distribution (flow) IMS communication (IMS)

NOISELESS DETECTOR WITH PARTICLE RECOGNITION Measurements of natural background radiation with a Medipix2-USB device equipped with a 700 mm thick silicon sensor (10 min exposure time). Various traces and tracks of X-ray photons, electrons and some a-particles are displayed. A rare cosmic muon track is clearly seen traversing the sensor horizontally. Study of the charge sharing in a silicon pixel detector by means of a-particles interacting with a Medipix2 device M. Campbell, E. Heijne, T. Holy, J. Idarraga, J. Jakubek, C. Lebel, C. Leroy, X. Llopart, S. Pospısil, L. Tlustos, Z. Vykydal, NIM-A 591, 2008

CURRENT NETWORK WITH 15 DETECTORS RUNNING LOW ACTIVITY MONITORING (ATLAS) 2015-10-23

NEUTRON IMAGING

NEUTRON IMAGING Current technology Mainly large area 3 He detectors Choppers to select neutron energy Future trends (?) Higher spatial resolution smaller detectors, closer to the object Semiconductor detectors Timing to select energy

2015-10-23 LIF STUFFED SILICON PIXEL DETECTOR

CONVERTER FILLED PORE MATRIX n + 6 Li 4 He + 3 H + 4.79 MeV n + 10 B 7 Li* + 4 He 7 Li + 4 He + 0.48 MeV g +2.3 MeV (93%) 7 Li + 4 He +2.8 MeV ( 7%) 2015-10-23

TECHNOLOGIES

THE HYBRID PIXEL DETECTOR Separates the different functions of the detection process Sensor layer Analog processing Digital processing Information storage and communication

WHAT IS COMMON? Sensor material Silicon for particles High-Z materials for gamma Converters for neutrons Analog input Pulse counting or integrating Digital data processing Digitizing pulses or stored charge Readout electronics Hybridization One or more levels Mounting and packaging Tiling Environmental protection Power and signals

DOPING GRADIENTS IN A SILICON WAFER Image taken with a MEDIPIX2 system at low bias. The effect is less significant at overdepletion 2015-10-23

CADMIUM TELLURIDE

3D SENSORS p+ n- n+ n- p+ n- n+ n- p+ n- n+ n- p+ 2015-10-23

PROBLEMS Uniformity especially in high-z materials Radiation hardness New processing techniques - compatibility Edgeless detectors for tiling 3D-detectors

TRENDS Separated analog and digital chips Separate optimization Different combinations Requires reliable high-density hybridization Advanced digital processing Auto-ranging (switch from counting to integrating) ADC in pixel Data storage Data compression and advanced readout schemes

2015-10-23 3D STACKING

PROBLEMS The cost of bump bonding Reliability Yield especially in multi level hybridization

2015-10-23 A MODULAR DETECTOR WITH SEAMLESS TILING

PROBLEMS Access with power and signal lines Heat dissipation Seamless tiling

CONCLUSION There is a need for a joint effort on radiation detector development in Europe. Critical mass for development as well as for production Common technology roadmaps Better access to research funding COST will support a network if granted ATTRACT will fund research projects

THANK YOU!