SiPMs for solar neutrino detector? J. Kaspar, 6/10/14

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1 SiPMs for solar neutrino detector? J. Kaspar, 6/0/4

2 SiPM is photodiode APD Geiger Mode APD V APD full depletion take a photo-diode reverse-bias it above breakdown voltage (Geiger mode avalanche photo diode) add quenching resistor repeat many thousand times

3 Huge variety of products Hamamatsu KETEK SensL Philips ST Microelectronics x 6 x 6 mm 0 00 um pixels 3

4 Theory of operation each pixel is an independent detector when pixel fires, it delivers charge (~e6 electrons) (regardless how many photons hit the pixel) then the pixel is dead for ~00 nsec (recovery time) ~000 times more pixels on the device than photons 4

5 Advantages fast like PMT, compact, cheap runs in magnetic fields, is non-magnetic high photo detection efficiency low voltage (typ. 40 or 70 V, diode orientation) much lower radioactivity than PMT 5

6 Disadvantages temperature dependence photo-effect (sec. order, cryo) probability electron triggers avalanche discharge gain (charge delivered by a pixel when it fires) breakdown voltage -> temperature monitoring -> in situ calibration (0,, ph comb, or laser) Frequency (number of events) (M= ) batteries not included Number of detected photons no standard pre-amplifier (think PMT without a base) 6

7 Cryo compatible photon absorption length depends on temperature easy down to 00 K (SiPMs like that) modified runs well in LXe, LAr anti-reflective coating (UV eff), cryo comp package K.Sato NIM A 73, 03 (47 430) charge carrier freeze-out < 50 K 7

8 Historical artifacts cross-talk -> optical trenches after-pulsing -> Si wafer purity high dark rate -> Si wafer purity slow pulses, pulse dependent on temperature -> metal (Ni) based quenching resistor high cost -> now much cheaper than PMT 8

9 cross-talk real photons emitted during avalanche discharge Fig. 9. Crosstalk ratio of the traditional and crosstalk-reduced MP nd afterpulse-reduced MPPC. problem for stat properties of pulses quenching resistor is several hundred kω. The product e.g. mean over sigma squared proxy resistance and capacitance significantly influences the pu for number of pixelsrecovery fired time of each pixel. Excessive resistance values optical trenches restrict the repetition rate and dynamic range by making t too long. It is very important to adjust this resistor value t the application. 9

10 after-pulsing incomplete discharge part trapped delayed release 0

11 metal quench resistor pulse decay time: R (quench resistor) * C (diode) poly-crystalline Si (old) Ni based (new)

12 examples of use Cerenkov telescopes (CTA) single photons, shaping, clipping, pole-zero correction hadron calorimeters ~000 photons Cerenkov, fast scint, or both positron emission tomography TOF

13 pre-amplifier batteries not included (like a PMT without a base) 3 possible designs: voltage amplifier with a shunt resistor pulse shapes ~40 nsec discrete trans-impedance amplifier pulse shapes ~0 0 nsec integrated trans-imp. amplifier pulse shapes ~5 nsec 3

14 g- example anomalous dipole moment of muon segmented lead fluoride calorimeter (Cerenkov) readout by SiPMs photons per event 4

15 SiPM board design goals energy scale (gain) stability comes from pulse amplitude 0. % (short time stability) timing resolution, time scale accuracy comes from the leading edge ~30 ps (different crystals), ~50 ps (pile-up) pulse width leaked energy vs. direct hit, lost muon SiPM board should preserve light profile 5

16 Monolithic design S PA-50 6 channel array x mm (active) area 50 µm pixels Ni-based quench. resistor through silicon vias optical trenches high purity Si wafer photons 6

17 LMH688 fully differential op-amp variable gain (6 6dB), SPI thermal coupling to crystal AC coupled output MMCX connectors feeding twinax cable x THS30 dual op-amp each sums 4 SiPM channels THS30 at unity gain sums four 4-sums 7

18 Knobs to turn 8 D4 D3 S57-05 D S57-05 R V -5V C 00p C 0.u C3 6.8u C9 6.8u C8 0.u R C7 00p R 4.99 R5 R3 4.9 C5 u C0 0.0u D S SOT3-5 Vout Vs- +In 3 -In 4 Vs+ 5 U THS30 Bias Bias Return SiPM anode to ground SiPM anode to virtual ground

19 Pulse shape intrinsic pulse (no pole zero correction) response to.5 nsec LED jitter from the pulse gen 0 ns 9

20 High rate capable ~5 MHz laser shots 000 photons per shot jitter from the pulse gen 0

21 pileup resolution

22 pileup resolution

23 Summary Geiger mode avalanche photodiodes Advantages: fast, compact, cheap, low-voltage devices, high detection efficiency much lower radioactivity than PMT cryo friendly Disadvantages and Challenges requires custom readout board gain is sensitive to temperature; must control environment 3