1. Silicon Photomultipliers and other advanced silicon sensors The INFN MEMS project R. Battiston INFN Perugia March 12th 2007

2. The INFN MEMS project The MEMS is a three years 8 M$ joint project within INFN and ITC-irst (Trento Italy), devoted to the development of innovative microelectronics silicon based devices using MEMS technologies  4 pilot projects are being developed since 2005, aiming to the developement of new types of radiation sensors for space based and ground based applications  1. Silicon Photomultipliers (for very low level photon counting)  2. Array of RF bolometers (for CMB next generation polarization detectors)  3. Cryogenic silicon detectors (for dark matter detectors)  4. 3D silicon detectors (for high rates silicon detectors)

3. MEMS Pilot project #1 Development of SiPM detectors MEMS Project PAT-INFN

4. Al ARC -V bias Back contact p n+n+n+n+ p n+n+n+n+  R quenching h p + silicon wafer Front contact What is a SiPM ? - V bias n pixels One pixel fired Two pixels fired Three pixels fired Current (a.u.) Time (a.u.) matrix of n microcells in parallel each microcell: GM-APD + R quenching originally developed by russian groups Out The advantage of the SiPM in comparison with GM-APD ANALOG DEVICE – the output signal is the sum of the signals from all fired pixels SiPM – photon detector candidate for many future applications N. Dinu (Elba 2006)

5. S. Haino (INFN Perugia)

7. A look on photon detectors characteristics VACUUM TECHNOLOGY SOLID-STATE TECHNOLOGY PMTMCP-PMTHPDPN, PINAPDGM-APD Photon detection efficiency Blue20 % 60 %50 %30% Green-yellow40 % 80-90 %60-70 %50% Red  6 % 90-100 %80 %40% Timing / 10 ph.e  100 ps  10 ps  100 ps tens nsfew nstens of ps Gain10 6 - 10 7 3 - 8x10 3 1  200 10 5 - 10 6 Operation voltage1 kV3 kV20 kV10-100V100-500V  100 V Operation in the magnetic field  10 -3 T Axial magnetic field  2 T Axial magnetic field  4 T No sensitivity Threshold sensitivity (S/N  1) 1 ph.e  100 ph.e  10 ph.e  1 ph.e Shape characteristicssensible bulky compactsensible, bulkyrobust, compact, mechanically rugged N. Dinu (Elba 2006)

8. Silicon Photomultiplier for the redout of a space born particle detector (Perugia and Rome 2 INFN) -> 2005 first time in space! <-

9. The layout developed at ITC-irst (2005) n+n+ p Technology Carachteristics 1) Very thin window 2) Optimized for the UV (420 nm) Current structure: - pixel 1x1 mm 2 - 25x25 microcells - single microcell: 40x40  m 2 1mm Geometry not yet optimized (geometrical factor today~ 30%) => to reach 45% Geometry Main block Wafer

10. Characterization Reverse IV measurement fast test to verify functionality and uniformity of the properties. (Performed on more than 1000 devices coming from 3 different batches) Dynamic characterization in the dark for a complete characterization of the output signal and noise properties (signal shape, gain, dark count, optical cross-talk, after-pulse) (performed on ~100 devices, coming from 2 different batches) Photodetection efficiency Energy resolution of SiPM coupled with LSO Timing performance

11. Single photoelectron resolution ADC Counts 1p.e. 2p.e. 3p.e. Excellent singl photon resolution!

12. Single photon timing performance Laser: - wavelength: 400 or 800nm - pulse width: ~60fs - pulse period: 12.34ns with time jitter <100fs Filters: to have ~1 photodetection per laser pulse SiPMs: 3 devices from 2 different batches measured PRELIMINARY 12.34ns timing sigma (ps) overvoltage (V) 1. More statistics needed 2. New tests planned by the end of the year.

13. Photodetection efficiency  V=2V 2.5V 3.5V 3V 4V QE vs Wavelength long : low PDE because low QE short : low PDE because avalanche is triggered by holes Measured on a diode Why this shape? Reduced by small epi thickness Reduced by ARC Geometrical Factor ~ 20% PDE=QE*Pt*GF QE=quantum eff. P t =avalanche prob. GF=geometrical factor 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0 PDE 350 400 450 500 550 600 650 700 750 800

14. Single SiPMs Micro-pixel: 50x50  m 2 Fill factor: 50% Micro-pixel: 100x100  m 2 Fill factor: 76% 1x1 mm 2, 2x2 mm 2 Micro-pixel: 40x40mm2 Fill factor: 42% 1x1 mm 2, 1.2 mm Ø QE*pt ~ 60% @ 400 nm  PDE ~ 28 – 45 % @ 400 nm

15. New Perugia Wafer layout (  march 2007) It includes: - square SiPMs with area: - 1x1mm 2 - 2x2mm 2 - 3x3mm 2 - 4x4mm 2 - circular SiPMs - linear arrays of SiPMs: - 1x8 - 1x16 - 1x32 - 4x4 matrix of SiPMs

16. Scientific applications  Exploit your imagination !  Replace PM on –Scintillator readout for triggering and timing (eg. in space, medical) –UV light detection from space –Cerenkov imaging for fast topological triggers –Fiber tracking –Calorimetry –……………..

17. SiPM + Scintillator (DaSiPM) Measurement set up: - 1x1mm 2 SiPM - 1x1x10mm 3 LSO scintillator ( peak =420nm) - Two SiPM, each one equipped with a LSO finger crystal directly positioned on the SiPM - Measurement in Coincidence with a   emitting 22 Na source  at 511keV) 1) Set up could be optimized 2) Geom factor to be optimized! Res FWHM ~ 21% Res FWHM ~ 29% SiPM Geom factor ~ 20% SiPM Geom factor ~ 30% PRELIMINARY New tests on 2x2 matrices are ongoing

20. Huge interest for these INFN detectors INFN projects : project DASiPM e DASiPM2 Medical PET project SiRAD Space Radiation project FACTOR Accelerator project P-ILC calorimetry at ILC International projects : Fermilab for ILC calorimetr CMS for HCAL outer barrel Wolfson Brain Imaging Center, Cambridge for PET/MRI applications Companies: SIEMENS medical applications PHILIPS medical applications PHOTONIS for phtomultipliers ISE srl per medical applications

21. Pubblicazioni INFN/ITC-irst (2006-2007) C. Piemonte “A new silicon photomultiplier structure for blue light detection” NIMA 568 (2006) 224-232 S. Moehrs et al. “Detector head design for small animal PET with Silicon Photomultiplier (SiPM)”, Physics in Medicine and Biology 51(2006) 1113-27. D.J.Herbert et al.”First results of scintillator readout with Silicon Photomultiplier” IEEE Trans Nucl Sci 53(1), 2006,389-394. D.J.Herbert et al. “Study of SiPM as a photodetector for scintillator readout” NIMA (2006) in press. C. Piemonte et al. “Characterization of the first prototypes of silicon photomultipliers produced at ITC-irst” to appear on IEEE TNS February 2007 D.J.Herbert et al. “The Silicon Photomultiplier in high resolution gamma camera for PET applications” NIMA (2007) to be published. N. Dinu et al. “Development of the first prototypes of SiPM at ITC-irst" NIMA (2007) to be published F.Corsi et al “ Modelling a Silicon Photomultiplier (SiPM) as a signal source for optimum front-end design” NIMA (2007) to be published G. Llosa et al. “Novel silicon photomultipliers for PET application” CD Conference Records IEEE NSS and MIC 2006 C. Piemonte et al. “New results on the characterization of ITC-irst silicon photomultipliers” CD Conference records IEEE NSS and MIC 2006 C.Mazzocca et al.”Electrical Characterization of Silicon Photomultiplier detectors for optimal fornt-end design” CD Conference Records IEEE NSS and MIC 2006

22. Who is producing SiPM ? In the ’90 russian groups: JINR, Dubna Obninsk/CPTA,Moscow Mephi/PULSAR,Moscow Since 2000 various european/japanese centers Hamamatsu, Japan (available) SensL, Ireland (available) IRST/INFN, Italy (available) MPI, Germany (not available yet) Official Website of MEMS INFN/IRST SiPM project: http://sipm.itc.it/

23. Final comments  A look to the future ……possible areas for collaboration among AMES and INFN ……….more and more integration among detectors and readout  3D electronics

24. R. Yarema

32. Conclusions  MEMS detectors coupled with VLSI electronics, will be the basic blocks for more and more sensitive and compact detectors for ground based and space based applications where power and mass are of essence  With the MEMS project INFN and I are developing some among the most interesting technologies in this field (SiPM, bolometeres arrays)  INFN could collaborate with AMES on the future development in this field of intelligent compact detectors.