The SiPM status on R&D in Munich

1. The SiPMstatus on R&D in Munich Nepomuk Otte MPI für Physik München

2. outline • working principle • status in Munich • measurement results • single photon resolution • gain • time resolution • recovery time • crosstalk • summary Max-Planck-Institute for physics Munich

3. SiPM – the working principle APD in geiger mode is a single photon counting device combine many small pixels into a matrix and connect them in parallel gain dynamic range in addition to single photon resolution Max-Planck-Institute for physics Munich

4. SiPM status in Munich • SiPM from MEPhI • 1mm2 with 576 pixels are in Munich and are being studied (see results on the following slides) • 9mm2 already in Munich • test station is being setup (cooling needed) • development at HLL • IDEA: use fully depleted Si with backside irradiation (no dead space) • simulations are in progress • APD in geiger mode • APD in proportional mode • test structures at the end of this year • first prototypes at the end of next year Max-Planck-Institute for physics Munich

5. picture a capacity is discharged by a certain amount of charge slope gives pixel capacity (C = 41fF) gain comparable to PMT‘s gain Max-Planck-Institute for physics Munich

6. timeresolution imroves with number of fired pixels time resolution J. Barral Max-Planck-Institute for physics Munich

7. recovery time no well defined deadtime better: “recovery time” pixel is not dead while it is recharging to bias voltage J. Barral with a dark count rate of 106 counts/s at room temperature 1‰ of all pixels will always be “dead” Max-Planck-Institute for physics Munich

8. single photon resolution very low excess noise factor leads to multiple photon resolution Max-Planck-Institute for physics Munich

9. crosstalk Hot-Carrier Luminescence 105 avalanche carriers 3 emitted photons A. Lacaita et al, IEEE TED (1993) photons generated in the avalanche travel into a neighbouring cell and initiate another geiger brakedown ways to reduce crosstalk: reduce gain and/or absorb photons between pixels Max-Planck-Institute for physics Munich

10. quantum efficieny determined by • intrinsic QE of Si • detection efficiency (depending on overvoltage) • active area (≈25%) P. Buzhan et al. NIM A 504 (2003) 48-52 Max-Planck-Institute for physics Munich

11. summary and outlook • we are developing SiPMs in two different ways: • in collaboration with MEPhI and Pulsar (B. Dolgoshein et al.) • with the semiconductor laboratory attached to MPI (WHI) and MPE • SiPM is a promising replacement candidate for conventional photomultipliers • high gain (106) • QESiPM≈QEPMT; expect boost by the application of microlenses • multiple photoelectron resolution up to ≈ 60 photo electrons • mechanical robust • possibility of mass production  reduction in costs • insensitiv to magnetic fields • low power consumption <40µW per 1 mm2 • dark count rate • crosstalk • R&D goals: increase SiPM size from 1 mm up to (3-5)mm increase in QE up to 70% Max-Planck-Institute for physics Munich

12. crosstalk at a gain of 5105 Max-Planck-Institute for physics Munich

13. Dark noise 22°C • noise sources • thermal generation • tunneling • cooling needed to satisfy EUSO requirements • count rate drops below 10kHz when operated at -50°C and gain >106 Max-Planck-Institute for physics Munich

14. Principle of operation • photon is absorbed in the depleted semiconductor • photo electron drifts into high field region and initiates an avalanche breakdown • passive quenching by resistor • deadtime ≈10-7 s given by the time constant to recharge the pixel‘s capacity P. Buzhan et al. http://www.slac-stanford.edu/pubs/icfa/fall01.html Max-Planck-Institute for physics Munich

15. Photon detector requirements for EUSO • overall photon detection efficiency > 50% (only about thousand photons per event) • sensitive range 330 nm to 400 nm (fluorescence light of N2molecules) • single photon counting with time resolution <10 ns (to avoid photon pileup) • dynamic range 100 phe/mm2 (to detect the Cherenkov flash) • dark noise < 106counts/s/mm2 (so light of night sky is limiting) • active detector area 4mm x 4mmwith as small as possible dead area (given by the resolution of the EUSO optics) Max-Planck-Institute for physics Munich