1. Performances of SiPMT array readout for Fast Time-of-Flight Detectors 13th Conference on Innovative Particle and Radiation Detectors Siena – 7-10 October 2013 M. Bonesini 1, R. Bertoni 1, A. De Bari 2, R. Nardo’ 2, M. Prata 2, M. Rossella 2 Presented by M. Bonesini INFN, Sezione di Milano Bicocca - Dipartimento di Fisica G. Occhialini 1 INFN, Sezione di Pavia - Dipartimento di Fisica Nucleare e Teorica 2

2. M. Bonesini - 13th IPRD conference2 Outline  Introduction  Scintillator based TOF detectors  PMTs vs SiPMT arrays  Test setup  Results  Conclusions

3. M. Bonesini - 13th IPRD conference3 PID methods Particle identification (PID) is crucial in most experiments (from  /K identification in B physics to e/  separation at 10 -2 level for p< 1GeV) At low momenta TOF methods are used (p  3-4 GeV/c)

4. M. Bonesini - 13th IPRD conference4 Particle ID with TOF  TOF based on measure of t over a fixed length L  Mass resolution dominated by  t (not measure of L, p)  Separation power in standard deviation Beam particle separation in HARP beam Tof, for a 3 GeV beam  K p d

5. M. Bonesini - 13th IPRD conference5 Examples of TOF detectors  Based on scintillator counters: simple to made, sensitive to B, read at both ends by PMTs, good resolutions -> 50-100 ps (depends mainly on L,N pe )  Based on PPC or spark chambers: some care in production, not sensitive to B, very good resolutions -> 30-50 ps  Based on RPC’s: cheap (suitable for large areas), not sensitive to B, R&D in development, very good resolutions -> 50 ps Rate problems

6. M. Bonesini - 13th IPRD conference6 Basics of double-sided scintillator counters Precise TOF and Hit position Pmt Scintillator + lightguide Tof resolution can be expressed as: Some points to look have high resolution tof’s

7. M. Bonesini - 13th IPRD conference7 Problems for high resolution scintillator based TOF (  t < 100 ps)  pl dominated by geometrical dimensions  (L/N pe )  scint  ps (mainly connected with produced number of  ’s fast and scintillator characteristics, such as risetime)  PMT PMT TTS (typically 70-150 ps) Additional problems in harsh environments: 1.B field (-> fine mesh PMTs/shielding of conventional PMTs ) 2.High particle rates (tuning of operation HV for PMTs)

8. SiPMT arrays vs PMTs M. Bonesini - 13th IPRD conference8 PMTs 1.Large active area > 0.5 – 1 inches 2.Gain G depends on external magnetic fields B (needs shielding, aside fine-mesh PMTs) 3.Good TTS: typical values in the range 150-400 ps 4.Fast PMTs are quite expensive: 1000-1500 E 5.Needs HV: typically 1000-2000 V 6.Low noise rate ~1KHZ SiPMT arrays 1.Active area up to 1x1 cm2 typically 2.Gain G insensitive to external magnetic fields, but depend on temperature T (needs feedback) 3.Good STPR response for single SiPMT ~140-300 ps 4.Quite cheap 5.Needs low voltages: ~30 V for SenSL, Advansid, ~70 V for Hamamatsu 6.High noise rate up to MHZ

9. Timing resolution of photo detectors M. Bonesini - 13th IPRD conference 9 From K. Arikasa NIM A422 (2000) Resolution improves: By decreasing active area As From G. Colazzuol (LIGHT11 2011)

10. M. Bonesini - 13th IPRD conference10 Conventional fast TOF with PMT readout have found application in many experiments MICE at RAL ( Hamamatsu R4998 PMTS) MEG at PSI (Hamamatsu fine mesh PMTs) AMS-02 exp (Hamamatsu fine mesh PMTs) Tof detectors

11. Studies of SPTR (timing for single photoelectrons) M. Bonesini - 13th IPRD conference11 Timing studies are usually done for single SiPMT (not arrays) with single p.e. For scintillation counters needs to study multiphoton response from V.Puill et al NIM A695 (2012) 354

12. A small remark M. Bonesini - 13th IPRD conference12 Timing studies are usually done with fast lasers (eg 30-50 ps FWHM ): good for single p.e. studies, but scintillator have typically 200-300 p.e. signals and scintillator risetime are in the 1-2 ns range … Needs laser signals that resemble more physical scintillation light

13. Experimental lab setup M. Bonesini - 13th IPRD conference13 Laser driver Sync out Prism injection system PMT L PMT R Fast photodiode Fast Amplifier BS Laser head VME tRtR t0t0 Light MM fiber x/y/z flexure (fiber launch system) Scintillation counter

14. Test setup: home-made laser system M. Bonesini - 13th IPRD conference14 1.Fast Avtech AVO pulser + Nichia violet laser diode ( ~408 nm) 2.Laser pulses width selectable between 120 ps and 3 ns length, with a ~200 ps risetime (simulate scintillator response) 3.Laser pulse height selectable to give scintillator response between a fraction of MIP and 10-50 MIPS 4.Laser repetition rate selectable between ~100 Hz and 1 MHz 5.The laser beam is splitted by a 50% beamsplitter to give a reference t0 on a fast photodiode (Thorlabs DET10A risetime ~1 ns) amplified via a CAEN A1423 wideband inverting fast amplifier (up to 51 dB, ~1.5 GHz bandwidth)

15. Some details M. Bonesini - 13th IPRD conference15 Laser injection system: Newport 20X microscope objective x/y/z Thorlabs micrometric flexure system Acquisition system: VME based (CAEN V2718 interface) VME CAEN TDC V1290A (25 ps res) VME CAEN QADC V792 VME CAEN V895 L.E. discriminator (typ discr values -50 -100 mV) home-written acquisition software

16. M. Bonesini - 13th IPRD conference16 Tuning of laser setup Tune laser settings to reproduce testbeam results (  t  with a single counter equipped with R4998 PMTs and MIP response Study single counter response substituting PMTS readout with SiPMT arrays readout Advantage as respect to cosmics is the possibility to collect a high statistics in a short time, with different exp conditions (amplifier tuning, …) From R. Bertoni et al., NIM A615 (2010) 14

17. M. Bonesini - 13th IPRD conference17 BC 404 scintillation counter (60 cm long, 6 cm wide) equipped with Hamamatsu R4998 PMTs (as in MICE expt) PMT signals with laser PMT signals with cosmics

18. Readout chain for SiPMT arrays M. Bonesini - 13th IPRD conference 18 SiPMT array custom mount 16 macrocells signals are summed up in the basette and then amplified Schematic of one ``basette’’

19. Custom amplifier M. Bonesini - 13th IPRD conference19 Amplifier: Custom made (INFN Pv) 1 or 2 channels Gain up to 100X (30X with pole zero suppression) Input dynamic range: 0-70 mV Bandwith : 600 MHz This may limit timing response, tests will be redone soon with a 50x PLS 774 amplifier (bandwith ~1.50 GHZ)

20. Amplifier performances M. Bonesini - 13th IPRD conference20 100X amplifierAmplifier linearity V out V in

21. SiPMT arrays under test M. Bonesini - 13th IPRD conference21 Available SiPMT arrays use 3x3 mm 2 or 4x4 mm 2 macro-cells arranged in 4x4 (or more) arrays. SENSL ArraySL-4-30035-CER arrays with 3x3 mm 2 macrocells, V op ~29.5 V Hamamatsu S11828-3344, S12642 arrays with 3x3 mm 2 macrocells, V op ~72.5 V Advansid FBK/IRST ASD-SiPM3S-4x4T (RGB) arrays with 3x3 mm 2 macrocells, V bkw ~28.5 V Advansid FBK/IRST ASD-SiPM4S-4x4T (RGB) arrays with 4x4 mm 2 macrocells, V bkw ~29.2 V We plan to extend study to new NUV types, better matched to scintillator light emission

22. M. Bonesini - 13th IPRD conference22 Results with conventional PMTs (as benchmark) Very low laser light intensity (1 MIP or less) Standard laser light intensity (2-3 MIP) V op = V 0 +  V

23. M. Bonesini - 13th IPRD conference23 SenSL ArraySL-4-30035-CER arrays Risetime of SenSL arrays much bigger than one of Hamamatsu or FBK/IRST Preliminary results quite bad, we need further studies with new blue extended arrays from SenSL to get conclusions SiPMT I-V characterization (our measure)

24. Results with FBK/IRST arrays M. Bonesini - 13th IPRD conference24 SiPMT I-V characteristics (manufacture specs)

25. M. Bonesini - 13th IPRD conference25 Results with FBK/IRST SiPMT arrays Standard light intensity  t ~60 ps at best, but RGB array !! Typical difference  TDC (converted in ps) :  t =   TDC /2 Vop

26. M. Bonesini - 13th IPRD conference26 Results with Hamamatsu S11828-3344 Arrays SiPMT I-V characterisation (our characterisation)

27. M. Bonesini - 13th IPRD conference27 Results with Hamamatsu S11828 Arrays Standard light intensity We foresee soon tests with Hamamatsu S12642 arrays, TSV package, where better results may be expected

28. Foreseen improvements M. Bonesini - 13th IPRD conference28 Higher bandwith amplifiers (bandwidth > 1 GHz) Extension of measurements to NUV extended SiPMT arrays (better matched to scintillator emission max ~400 nm) Use of better signal cables (eg RG213 instead of RG58) See effect of CF discriminators vs LE discriminators (even if we expect no big change: laser light signal/cosmics signal at counter center + equalized response of photodetectors) Test of fully equipped detectors at BTF

29. M. Bonesini - 13th IPRD conference29 Conclusions SiPMT arrays may be a good repacement for fast PMTs in scintillator time-of-flight system Preliminary conclusions show a “comparable” timing resolution with fast PMTs Clearly results must be validated by testbeam (one at BTF is foreseen) Some optimization may be needed: use of fast (> 1 GHz) amplifiers, NUV SiPMT arrays (instead of RGB ones) to better match scintillator emission Acknowledgements: many thanks Mr. F. Chignoli, G. Stringhini and O. Barnaba for skilful help and work in the setup installation and laboratory measurements and Dr. Bombonati of Hamamatsu Italia

30. Backup slides M. Bonesini - 13th IPRD conference30

31. Estimation of N pe M. Bonesini - 13th IPRD conference31 If QADC P.H. distribution is fully described by photoelectron statistics : N pe =( /  R ) 2 where peak value R and sigma  R are obtained with a gaussian fit. From published data (R. Bertoni et al NIM …) we expect 200-300 pe per MIP; from QADC fit we obtain that our standard light intensity is equivalent to 2-3 MIP

32. Timing resolution as function of discriminator threshold M. Bonesini - 13th IPRD conference32

33. M. Bonesini - 13th IPRD conference33 Fine Mesh Photomultiplier Tubes Secondary electrons accelerated parallel to the B-field. Gain with no field: 5 x 10 5 – 10 7 With B=1.0 Tesla: 2 x 10 4 - 2.5 x 10 5 Prompt risetime and good TTS Manufactured by Hamamatsu Photonics Measures at INFN LASA laboratory to study behaviour in B field (up to 1.2 T ) as respect to gain, rate capability, timing R5505R7761R5924 Tube diameter1”1.5”2 “ No. Of stages1519 Q.E.at peak.23.22 Gain (B=0 T) typ5.0 x 10 5 1.0 x 10 7 Gain (B=1 T) typ1.8 x 10 4 1.5 x 10 5 2.0 x 10 5 Risetime (ns)1.52.12.5 TTS (ns)0.35 0.44