Proof of feasibility of VSiPMT (Vacuum Silicon PhotoMultiplier Tube) A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES Proof of feasibility of VSiPMT (Vacuum Silicon PhotoMultiplier Tube) D. Vivolo Univ. Federico II and INFN Naples, Italy 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

D. Vivolo - Proof of feasibility of VSiPMT A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES Outline VSiPMT Geant4 simulations Experimental setup Prototype test Perspectives 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Beyond PMTs To date, a crucial role in astroparticle experiments has been played by PhotoMultiplier Tubes (PMTs). However they suffer of many drawbacks : fluctuations in the first dynode gain make single photon counting difficult; Moreover the next generation of experiments will require further improvements in photon detectors the linearity is strongly related to the gain and decreases as the latter increases; performances New generation of photodetectors, based on inverse p–n junction: the transit time spreads over large fluctuations; the mechanical structure is complex and expensive; PIN photodiodes: no gain; sensitivity to magnetic fields; avalanche photodiodes (APD): gain of few hundreds; the need of voltage dividers increases failure risks, complexity in the experiments designs and power consumption. avalanche photodiodes in linear Geiger-mode (SiPM): gain of 105 – 106. 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

small sensitive surface A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives SiPM technology Attractive features high quantum efficiency low operation voltages compactness robustness weak sensitivity to the magnetic fields ! ! ! Limit small sensitive surface (at present silicon wafer costs and the thermal dark current limit the dimensions of the SiPM photo detector at few mm2) 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

Surface increase: our purposes A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Surface increase: our purposes Vacuum Silicon PhotoMultiplier Tube (VSiPMT) SiPM Photocathode 1st stage Cilindrical Focusing Electrode 2nd stage Conical Focusing Electrode Optical Concentrators + digital noise reduction circuit 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

D. Vivolo - Proof of feasibility of VSiPMT A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Timeline 2007 2013 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

+ VSiPMT: design Design Combination of SiPM with vacuum technology A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives VSiPMT: design Combination of SiPM with vacuum technology replacing the dynodes structure of a PMT with a SiPM (Vacuum Silicon PhotoMultiplier Tube, VSiPMT) Design Hemispherical vacuum glass PMT standard envelope composed by: a photocathode for photon-electron conversion In such a configuration, the SiPM acts both as a non-imaging concentrator and as an electron multiplier with G≈105 - 106, similar to the dynode chain of a classical PMT. + photoelectrons an electric field that accelerates and focuses all the photoelectrons to a small focal area covered with the SiPM 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

The quartz window has an anti-reflective function: A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Geant4 Simulations Geant4-based simulation of electron backscattering over SiPM Quantities: Simulated device 2 sets of simulations Backscattering coefficient Incoming electron beam Normally incident beam Beam energy 1 - 20 keV Range in Si Total released energy Quartz layer (0.15 mm) Si substrate (5mm) Backscattering energy fraction Average energy loss in Si Variable incident angle Beam energy 10 keV The quartz window has an anti-reflective function: Backscattering coefficient is 12.6% with quartz layer and 14.1% without it 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

Geant4 Simulations: highlights/1 A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT VSiPMT Geant4 Simulations Exp. Setup Experimental Setup KF technique KF technique Prototype test Perspectives KF technique Geant4 Simulations: highlights/1 Normally incident beam Beam energy 1 - 20 keV Variable incident angle Beam energy 10 keV E [keV] Range in Si [mm] 1.2 mm @ 10keV Range in Si [mm] 0.42 mm @ 75° Incidence angle [°] 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

Geant4 Simulations: highlights/2 A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Geant4 Simulations: highlights/2 Normally incident beam Beam energy 1 - 20 keV Variable incident angle Beam energy 10 keV 0.5 @ 75° 0.126 @ 10 keV Backscattering coefficient Incidence angle [°] 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

Experimental Setup/1 Test of SiPM performances as an electron detector A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Experimental Setup/1 8 MeV 3+C beam Backward secondary e- collected (stripping) Energies up to 9 keV required. Electrostatic grids system for acceleration and deflection. High vacuum (10-6mbar) Test of SiPM performances as an electron detector Low-energy electron beam required Ion beams accelerated by TTT3 Tandem Accelerator at MeV energies bombarding a thin 12C foil (30 mg/cm2) 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

Iin = Ibw  ASiPM/Aspot ≈ 6nA A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Experimental Setup/2 average energy loss in collisions with Carbon atomic electrons per unit length: dE/dx = 152 eV/Å in 100Å each 3+C ion extracts ∼ 1300 e- Measured 8 MeV 3+C beam current Ip=400pA Backward electron current Ibw = Ip x 1300 = 520pA Input electron current on SiPM Iin = Ibw  ASiPM/Aspot ≈ 6nA ASiPM = 1 mm2 Aspot ≈ 0.9 ± 0.1 cm2 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

Preliminary estimation of Electron Detection Efficiency A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Results Evidence of the feasibility of the SiPM as an electron counter Dark condition Responses for multiple triggers overlaid Peak values hystogram Separated waveforms Preliminary estimation of Electron Detection Efficiency EDE ≈ (23 ± 9) % 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

p+npn+ configuration, special non-windowed series for e optimization. A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Prototype HV SiPM Bias Amplifier GND pe g p+npn+ configuration, special non-windowed series for e optimization. Lower voltage required with respect to simulations (-2,5/3 KV expected). 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

Excellent photon counting capability! A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Prototype: waveforms Peak values hystogram VSiPMT illuminated by a pulsed laser light at low intensity (407nm) oscilloscope triggered in synch with the laser Responses for multiple triggers are overlaid Well separated waveforms Excellent photon counting capability! 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

Prototype: efficiency Preliminary results on 50mm prototype A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Prototype: efficiency photons photocathode dynode photoelectrons photons photocathode -2/3 KV -2/3 KeV SiPM (70 V) photoelectrons PMT Efficiency VSiPMT Efficiency e = e photocathode x e 1st dynode e = e photocathode x e SiPM (50) 0,30 ≈ 0,38 x 0,8 0,23 ≈ 0,38 x 0,61 e = e photocathode x e SiPM (100) Preliminary results on 50mm prototype 0,30 ≈ 0,38 x 0,78 e ≈ 0,2 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

Prototype: operating point A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Prototype: operating point preliminary photons photocathode HV 2 - 5 KeV SiPM (70 V) photoelectrons Efficiency is highly stable over 3200 V No need for high voltage stabilization 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

Prototype: xy scan preliminary 7mm x 7mm bialkali photocathode A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Prototype: xy scan preliminary 7mm x 7mm bialkali photocathode 1mm2 SiPM Homogeneous efficiency ≈ 0.2 over a 9mm2 surface Surface increase factor ≈ 9 Standard technology Focalization optimization is possible WORK IN PROGRESS 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

Prototype: gain High gain (105 – 106), linear trend preliminary A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Prototype: gain Peak values hystogram preliminary Area hystogram Measure of the charge corresponding to 1 pe (peaks in area hystogram) High gain (105 – 106), linear trend 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

Highlights on preliminary results A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Highlights on preliminary results PMT VSiPMT comparison Efficiency Photocathode x 1st dynode (0,8) Fill factor SiPM (vs..1) ≈ equivalent Gain 105 - 106 Timing nsec fractions of nsec (no spread dynodes) + VSiPMT Linearity 100-300 depending on gain -Pe spot over all SiPM surface -dim. SiPM e n. of cells not depending on gain in progress Power Consumption Divider Dissipation No dissipation: just Amp. G=5-7 (50mW) +VSiPMT Stability H.V. H.V. stabilization fot stable gain No H.V. stability (plateau) Single photon detection difficult Photon counting Dimensions & Costs Compactness-low cost 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

Perspectives Crucial features under investigation A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES VSiPMT Geant4 Simulations Experimental Setup Prototype test Perspectives Perspectives Preliminary results are extremely encouraging Prototype test in progress...much work still to be done Crucial features under investigation Focusing system optimization More accurate efficiency measurements in progress Timing performances - TTS Linearity optimization – Dynamic range Low temperature performances ... 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

D. Vivolo - Proof of feasibility of VSiPMT A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES Thank you 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

D. Vivolo - Proof of feasibility of VSiPMT A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES Backup slides 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

D. Vivolo - Proof of feasibility of VSiPMT A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES Normally incident beam Beam energy 1 - 20 keV Variable incident angle Beam energy 10 keV Incidence angle [°] Backscattering energy fraction q= Einc (Einc – Erel) q increases with q (q=0.68 @ 75°) Backscattering energy fraction q=0.22 @ 10 keV E [keV] 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

D. Vivolo - Proof of feasibility of VSiPMT A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES Normally incident beam Beam energy 1 - 20 keV Variable incident angle Beam energy 10 keV E [keV] Total released energy [keV] Small until 4 keV 7,8 keV at 10keV Total released energy [keV] 3.5 keV @ 75° Incidence angle [°] 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

D. Vivolo - Proof of feasibility of VSiPMT A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES Normally incident beam Beam energy 1 - 20 keV Variable incident angle Beam energy 10 keV E [keV] Average energy loss in Si [MeV/cm] 16 keV/cm @ 10keV Average energy loss in Si [MeV/cm] 6.5 keV/cm @ 75° Incidence angle [°] 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT

Laser beam characterization A Kalman Filter approach for track reconstruction in a neutrino telescope: road to ANTARES Laser beam characterization High gain 2.75 x 105 at 72.8V bias Low breakdown voltage (70V) Very linear output signal Single photon sensitivity SiPMs have better performances than PMTs with lower power consumption Geant4 Simulation 10 keV electron beam 50% at 75° 68% at 75° Backscattering coefficient for a normally incident beam is12.6% Backscattered energy fraction is 22% for normally incident beam 14.2% without anti-reflection quartz window For small incidence angle the SiPM represents a valid solution to substitute the classical dynode chain of PMTs. 23/05/2013 D. Vivolo - Proof of feasibility of VSiPMT