The story of Medipix: Images by processing of single quanta

1. The story of Medipix: Images by processing of single quanta Erik H.M. HEIJNE IEAP-CERN-Nikhef Medipix 20th Anniversary

2. Medipix is the people who make it – 10 years- Prague 2009 • Medipix scientists started the IWoRID workshop: 1st + 20th in Sundsvall

3. 16 (now 17) Medipix2 collaboration partners • U INFN Cagliari • CEA-LIST Saclay • - CERN Genève • U d'Auvergne Clermont • - U Erlangen • - ESRF Grenoble • - U Freiburg • - U Glasgow • - IFAE Barcelona • - Mitthoegskolan • - MRC-LMB Cambridge • - U INFN Napoli • - NIKHEF Amsterdam • - U INFN Pisa • - FZU CAS Prague • IEAP CTU in Prague • SSL Berkeley • - U Houston SPOKESMAN Michael CAMPBELL

4. Medipix collaborations 1999 - 2019 • overall, 33 different institutes from 15 countries – 5 non-member states CERN

5. Commercial Partners • source: Michael Campbell CERN KT presentation 13 June 2019 so far 8 companies have Medipix licenses range of application areas still mostly in X-ray imaging & analysis

6. International collaboration facilitated through CERN Original idea of CERN: achieve critical mass for real big projects through collaboration need pool of excellent scientists and technicians need visibility & support for institutes and potential users need critical amounts of money need place to meet, and to work together

7. Medipix website • http://medipix.web.cern.ch/ CERN is the ‘neutral’ meeting place with facilities that allows teams from around the world to work and obtain results together, in an effective way

8. Particle physics & Medipix • Particle physics studies properties and interactions of single, elementary particles – ‘energetic quanta’ • sophisticated instruments and methods are continuously under developmented for this study

9. single quanta recorded in sensitive emulsion, since 1930’s dE/dx with δ-electrons • ions in cosmic rays • Powell, Fowler & Perkins- Pergamon 1959 Z=12 Z=14 Z=20 25GeV photon 50 µm • 1980 • charm decay in Omega experiment WA58 • M.J. Adamovich et al., Observation of pairs of charmed particles produced by high-energy photons in nuclear emulsions coupled with a magnetic spectrometer, Phys.Lett. 99B (1981) 271-276 50 µm

10. single quanta recorded in sensitive emulsion, since 1930’s dE/dx with δ-electrons • ions in cosmic rays • Powell, Fowler & Perkins- Pergamon 1959 Z=12 Z=14 Z=20 complete, very detailed images 25GeV photon 50 µm • 1980 • charm decay in Omega experiment WA58 • M.J. Adamovich et al., Observation of pairs of charmed particles produced by high-energy photons in nuclear emulsions coupled with a magnetic spectrometer, Phys.Lett. 99B (1981) 271-276 50 µm

11. ATLAS INTERACTION Imaging today all electronic 3-dimensional reconstruction, but lack of detail here many tracks + 2 “Jets” 40 million / sec secondary vertex: particle with short-lifetime is a messenger for new phenomena blow-up in later slide source: CERN-ATLAS

12. new since 1990: Si pixel detectors for single quanta in LHC • charm & beauty/bottom quanta with ‘long’ lifetime messengers for interactions with new particles • ~10-13 s with ~mm pathlength & secondary vertices

13. ATLAS INTERACTION ATLAS event details around primary vertex two secondary vertices: “messengers” Note 1 cm scale all this is INSIDE beam pipe  7cm but tracker is OUTSIDE 1 cm source: CERN-ATLAS

14. Particle physics & Medipix • Particle physics studies properties and interactions of single, elementary particles – ‘energetic quanta’ • sophisticated instruments and methods are continuously under developmented for this study

15. Particle physics & Medipix • Particle physics studies properties and interactions of single, elementary particles – ‘energetic quanta’ • sophisticated instruments and methods are continuously under developmented for this study • main advantages of Si pixel detectors in HEP: • - unequalled rate capability in high flux >107 s-1 • thanks to small elements & ns response / recovery • - 100% efficiency with low noise low capacitance few fF • - µm precision, very thin sensor layers possible expertise in HEP exploited for radiation imaging ~1995 first initiative INFN+CERN+Glasgow+Freiburg

16. Si pixel imaging detectors for single quanta • looking at the web: • single photon/quantum imaging most often is done using a single channel detector, that analyzes in a sequential fashion quanta emerging from a sample, created by a scanning beam of nanofocus X-ray or electrons • also in such a setup, a parallel imager could make a difference: simultaneous views of one spot position under many angles

17. Medipix: what is then so special ? • we – Medipix scientists – are very proud of our achievements • and rightly so, with lots of publications • BUT • generally we seem to make the mistake, • to not mention clearly why Medipix imagers are very different • until 1998 no electronic, pixelated imagers existed which could record images by processing photon-quanta one by one and in a fully parallel manner in many 1000s of cells • potential of this parallel, single quantum processing begins to be exploited • which properties of the quanta should / could be measured ?

18. Si pixel imaging detectors for single quanta • imaging of radiation • particle/nuclear physics, dosimetry, space environment • what is it: analysis of individual quanta • info: dE/dx cluster shape time-of-flight ToF ..... • contrary to imaging in the visible range: no filters • imaging with penetrating radiation • variety of objects: medical, materials, art, equipment.. different types of radiation: X, electrons, neutrons.. • in-pixel thresholded counting fairly trivial • spectroscopic recording in single exposure #bins • more sophisticated processing possible in future

19. The story of Medipix: Images by processing of single quanta Erik H.M. HEIJNE IEAP-CERN-Nikhef Medipix 20th Anniversary

20. visualisation of single incident quantasea level space station ISS

21. natural quanta/particles in Medipix Si imager 256 x 256 pixels 300 µm Si sensor used as dosimeter e- can recognize specific quanta electrons photons 100% up to ~15 keV low % for meV alpha (thermal) neutrons few % m.i.p. & ions n->a photon muon energetic e- large dynamic range by adjustable exposure ms – minutes Frame taken in CTU Prague

22. Dosimetry at the Int Space Station ISS orbits at ~400km, units µG/min

23. dosimetry with TPX on ESA satellite Proba-V frames in LEO orbit ~800km, different positions courtesy Carlos Granja IRAP-CTU (2015) ion track with ∂ electrons

24. CMOS circuit design is key to new imagers • 1960s 1D arrays of diodes, separately connected • CCD array of capacitors with single port • designed for memory or visible imaging • 1980s CMOS or CCD matrix hybridized with sensor matrix for infrared or other • still charge integrating sensor elements • pixel detectors proposed now ‘nuclear’ signal processors in all pixels • 1990s CMOS imagers for visible: 3 or 4 transistors

25. Medipix3 Cell layout 170 µm • R. Ballabriga et al. • The Medipix3 prototype -2006 IEEE-NSS

26. Medipix2: Mpix2MXR20 (2005) 14111 µm

27. Evolution in complexity of our readout chips • R. Ballabriga et al. • The Medipix3 prototyp Medipix1 = PCC1 much more in next talks • Xavi Llopart ESE CERN 2019

28. parallel in-pixel quantum processing • shrinking dimensions in CMOS can be used to increase sophistication of functions in the pixels, which do not shrink as much • in particle physics, quite large pixels have been implemented with revolutionary functionality for processing each quantum

29. parallel in-pixel quantum processing • ~1100 e-h pairs for quantum energy >4keV • continuously sensitive amplifier and comparator circuit allows noise elimination by thresholding hit counting • multiple thresholds coarse spectroscopy • inter-pixel connections for cluster-sum • clock in pixels, with <ns timing allows • ToA • ToT + off-pixel spectroscopy & dE/dx (smaller pixels needed) • To F relative, or absolute if start of flight is known • point of incidence (needs track reconstruction for each quantum) • what else?? • much work remains: calibrations, transmission, big data, .....

30. Projections for Si imagers Eric Fossum, Pixel Workshop Bari, 1996

31. Complexity for CMOS Si imagers µm pixel size imagersfor visible µm µm 0.01 0.01 2 nm 2 nm 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 after Eric Fossum, Pixel Workshop Bari, 1996 illustrates growing gap between CMOS features and pixel area in imagers

32. Complexity for CMOS Si imagers pixel size radiation imagers µm pixel size imagersfor visible µm µm 0.01 0.01 2 nm 2 nm 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 after Eric Fossum, Pixel Workshop Bari, 1996 illustrates growing gap between CMOS features and pixel area in imagers

33. Systems aspects the imager chip is only the first part of the chain

34. miniature USB readout • this handy USB version made the Timepix very popular • runs with ‘Pixelman’ software • IEAP-CTU Prague first design Jan Jakubek/Zdenek Vykydal • current version: Minipix @Advacam • software ‘Pixet’

35. Readout systems • various readout systems have been developed in participating institutes or companies (really none at CERN)

36. Progress in X-ray images of objects: 1998 - 2019 • advances in processing of single photons • full potential now begins to be exploited Lukas Tlustos ~2001 with first PCC MARS Bio imaging Canterbury X-ray CT with Medipix3 2019

37. Radiation imagers for schools and amateurswith educational kit IEAP/CTU, Prague Jablotron & IEAP/CTU, Prague AdvaCam & IEAP/CTU, Prague CERN Timepix imager inside http://ardent.web.cern.ch/ardent/ardent.php

38. Future developments ? • larger arrays without cracks; use TSV • additional characteristics of incident quanta? • lower quantum energy, better resolution EUV possible? need lower noise, smaller pixels • even faster timing: <10ps need thinner Si or faster sensor material • better use of cluster shape • exploit dE/dx along tracks: Bragg peak • need smaller pixels • polarization of quanta • other properties? other particles?

39. Future developments ? • much smaller pixels, nearer to matrices for visible also thin, typically 3x3x3 µm3 attoFarad capacitance: single electron  some µV monolithic integrated front-end in sensor layer multiple stacked layers TSV through-Si-via copper-to-copper interconnect pitch ~1µm • apply recent SONY/Samsung imager technology • well matched to some applications: good for particle tracking speed, noise, precision • imaging with micro-channel plates visible, neutrons,...

40. Samsung 0.9 µm imager with deep-etched separation ISSCC 2018 paper 5.3 use 4µm i(earlier 2.7µm) to improve signal for red light physics does not really need trenches between pixels charge sharing anyway, also delta rays

41. Stacked imager Sony : ADC connected to each pixel M. Sakakibara et al.Sony; ISSCC 2018 paper 5.1

42. Complexity for CMOS Si imagers pixel size radiation imagers my proposal for 3µm tracker in ~2025 µm pixel size imagersfor visible µm µm 0.01 0.01 2 nm 2 nm 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 after Eric Fossum, Pixel Workshop Bari, 1996 illustrates growing gap between CMOS features and pixel area in imagers

43. Future developments ? imaging systems with 1012 pixels need new readout sort of fast transmission processing of single quanta/atoms 1023 per mol of material analysis needs artificial intelligence for dealing with exabytes of data is it all worth it?

44. Conclusion