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Pixilated Photon Detectors and possible uses at ILC and SLHC

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## Pixilated Photon Detectors and possible uses at ILC and SLHC

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**Pixilated Photon Detectors and possible uses at ILC and SLHC**WSU, 23 Oct 09 Rubinov “at” fnal.gov Rubinov, WSU HEP seminar**Intro to SiPM**Rubinov, WSU HEP seminar -- T. Nakaya (Kyoto) @ Pixel08 -- • Q: What is an SiPM? • A: SiPM (Silicon Photo Multiplier) MRS-APD (Metal Resistive Semiconductor APD) SPM (Silicon Photo Multiplier) MPGM APD (Multi Pixel Geiger-mode APD)AMPD (Avalanche Micro-pixel Photo Diode)SSPM (Solid State Photo Multiplier) GM-APD (Geiger Mode APD)SPAD (Singe Photon Avalanche Diode)MPPC (Multi Pixel Photon Counter) From Yamamoto Pixelated Photon Detector 2**Rubinov, WSU HEP seminar**Photodiodes, Avalanche, Geiger Mode From A Para (Fermilab) Photodiodes: • p-n junction , reverse bias • Electron-hole pair generated by an incoming photon drifts to the edges of the depleted region • I(t) = QE * q * dN/dt(t) • Absolute calibration • No gain • Suitable for large signals 3**Rubinov, WSU HEP seminar**Photodiodes, Avalanche, Geiger Mode From A Para (Fermilab) Avalanche Photodiodes: • Photodiodes operating at higher bias voltage • Higher voltage stronger electric field higher energy of drifting carriers impact ionization Gain • (Im)Balance between the number of carriers leaving the depletion region and the number generated carriers per unit time: dNleave/dt > dNgenerated/dt • Stochastic process: signal quenches when the ‘last’ electron/hole fails to ionize. • Large fluctuations of the multiplication process Gain fluctuations Excess noise factor (beyond-Poisson fluctuations) 4**Rubinov, WSU HEP seminar**Photodiodes, Avalanche, Geiger Mode From A Para (Fermilab) Geiger Mode Avalanche Photodiodes: • Avalanche Photodiodes operated at the elevated bias voltage. • Larger field carriers gain kinetic energy faster shorter mean free path • Breakdown voltage: nothing really breaks down, but dNleave/dt = dNgenerated/dt(on average) at this voltage • Some electrons can generate self-sustaining avalanche (current limited eventually by the series resistance) • Probability of the avalanche generation increases with bias voltage (electric field) • Operation mode: one photon (sometimes) ~1e6 electron avalanche 5**First prototype of MAPD (MRS APD 1989)**Rubinov, WSU HEP seminar First metall-resistor-semiconductor APD (MRS APD) structure was designed by A.Gasanov, V.Golovin, Z.Sadygov (russian patent #1702881, from 10/11/1989) PDE of MRS APD is just few % AnfimovNikolay, Dubna, JINR Low-light intensity spectrum of MRS APD (A. Akindinov et. al, NIM387 (1997) 231**Rubinov, WSU HEP seminar**Q=CD*(Vbias-Vbd) 9**Intro to SiPMs**Rubinov, WSU HEP seminar • Analogy • When comparing PMTs to SiPMs, SiPMs enthusiast usually list advantages of SiPMsBORING and PREDICTABLE • I list advantages of conventional PMTs on next slide from a tube company**PMT vs SiPM**Rubinov, WSU HEP seminar Adapted from IEEE & Eric Barbour Tubes: Advantages 1. Characteristics highly independent of temperature. 2. Wider dynamic range, due to higher operating voltages. 3. Very low dark current. SiPM: Disadvantages 1. Device parameters vary considerably with temperature, complicating biasing. 2. May need cooling, because lower operating temperature may be required.**Analogy?**Rubinov, WSU HEP seminar I think we have seen transition from vacuum tubes to solid state before. Transistors are not tiny vacuum tubes and SiPMs are not tiny PMTs I think that the reason we have transistors instead of tubes boils down to this: $**Is the SiPM the perfect LLL sensor?**Rubinov, WSU HEP seminar • Die eierlegende Woll-Milch-Sau (german) (approximate english translation: all-in-one device suitable for every purpose) R. Mirzoyan There will be different devices optimized for different applications**SiPM Animal**Rubinov, WSU HEP seminar • Research in SiPMs is very active, in many different directions – I’m not going to do a survey • Extended blue sensitivity (Cherenkov light, dual readout calorimetry) • Increased PDE ( muon detectors) • Reduced crosstalk (improved noise factor) • Improved timing (PET) • Large area (Cherenkov) • Increased dynamic range (Calorimeters) • LOWER COST (everyone)**Areas of interest for LHC**Rubinov, WSU HEP seminar • Issues of special interest to SLHC (more detail on CMS specifics later) • Radiation hardness • Dynamic range/Linearity • Stability (radiation, temperature and time) • CERN has a strong, active community working on all these issues**Areas of interest for LC**Rubinov, WSU HEP seminar • Issues of special interest to LC (more detail on SiD specifics later) • Blue sensitivity • Cost/unit area • Optical coupling to detector • Calice is a strong collaboration doing fantastic work on these areas**Understanding SiPM operation**Rubinov, WSU HEP seminar • Here I'm going to focus on 2 issues • DC measurements • Vb determination • Rquench determination • Cross talk measurement • Pulse measurements • Afterpulsing measurements**Rubinov, WSU HEP seminar**DC Measurements • Static characteristics - IV curves at fixed temperatures: • Keithley 2400 sourcemeter • Temperature controlled chamber • Labview data acquisition program • Forward bias series (quenching) resistance • Reverse bias breakdown voltage, integral behaviour of the detector s a function of the operating temperature 18**Rubinov, WSU HEP seminar**Forward Bias Scan Limited by quenching resistor dI/dV = 1/R Exponential growth with V Resistance decreases with temperature (polysilicone) 19**Rubinov, WSU HEP seminar**Detector type Quenching Resistor @ 25 oC, k dR/dT k/oC 1/R dR/dT 25 200 2.23 0.011 50 105 1.08 0.010 100 85 0.91 0.011 Quenching Resistance Summary for MPPCs From A Para (Fermilab) 20**Rubinov, WSU HEP seminar**Reverse Bias Scan Quenching resistance 1 V above breakdown I~5x10-7A Gain ~ 4x106 ‘Photodiode’ current level ~ 10-13 A How relevant is the current below the breakdown voltage? Temperature 100 pA Breakdown From A Para (Fermilab) 21**Vbd(T). Preliminary analysis**Rubinov, WSU HEP seminar IRST #30 Fermilab August 29th 2008 Diego Cauz University & INFN of Udine**Rubinov, WSU HEP seminar**Cross Talk Measurement Ratios of rates give relative probabilities of 1,2,3 extra pixels firing due to cross-talk Single avalanche rate Single + 1 cross talk Single +2 cross talk Single +3 cross talk**Rubinov, WSU HEP seminar**Cross Talk Rates as a Function of Bias Voltage • Cross talk probability increases with the bias voltage • Cross talk probability is bigger for larger size pixels But… The cross talk is mediated by infrared photons produced in the avalanche, hence is ought to be proportional to the gain. And different size pixel detectors have different gain !**Cross Talk Probability as a Function of Gain**Rubinov, WSU HEP seminar • At the same gain the cross-talk probability is much larger for smaller size pixels • At the operating point the Hamamatsu detectors have very small cross talk (~few %)**Pulse measurements**Rubinov, WSU HEP seminar • MPPC-11-050C#37 at 71.1deg F operating at 69.81 (recommended V is 70.02 at 25C) • Current reading is 0.044uA • 1pe is about 13.25mV**Rubinov, WSU HEP seminar**A little bit about after pulses Observed signal grows with the bias voltage. This growth has several components: • increase of the gain • increase of afterpulsing. The latter is a much bigger effect. So what?? Afterpulses provide a kind of additional gain. True, but this contribution fluctuates degrades the charge measurement resolution (excess noise factor). Relative width of the observed pulse height spectrum slightly decreases with bias voltage for 10 nsec gate (presumably a reflection of the increased number of detected photons), but it increases for longer gates. Bottom plot shows a contribution to resolution from fluctuations of the afterpulses contribution in different gates.**Rubinov, WSU HEP seminar**Detector Recovery / Afterpulsing • Pulse arrival distribution: clear afterpulsing for about~ 1 sec • At least two components: • 1=39 nsec • 2=202 nsec • These components probably correspond to traps with different lifetimes 28**Rubinov, WSU HEP seminar**F. Retiere @ NDIP08 S10262-11-050C short~15ns Photo-Electrons long~85ns Dark-noise rate Time after the first pulse (ns) Time after the first pulse (ns) 29**Rubinov, WSU HEP seminar**• After subtracting the effects of cross-talk + after pulse, the dark noise is found to be linear to V. F. Retiere @ NDIP08 30**SiPM pulse shape**Rubinov, WSU HEP seminar • Actually, there is some subtle issues in measuring pulse shape**The idea is to model the avalanche as a fast, brief (almost)**short across a capacitor (Cdet) which is then recharged through a resistor (Rq) • this is one micro pixel, so 1 pe by definition • Also include parasitic capacitance across this resistor (Crq) • Also model the rest of the device by a collection of Cdetp, Rqp, Crqp • the parallel stuff is important, it gives that characteristic “kink”**This kink**is this plus this There are 4 values of Crq from 1 to 10 fF. So Crq is important for “spike” but not “tail”**Crq= 10fF, 5fF, 2.5fF, 1fF**• and this is what we are left with... • So the size of the “spike” makes a huge difference to the shape of what is observed- including the integral**But, the slow component is not so affected**• This fig has 8 plots: before and after the filter for each value of Crq**But its even worse than that...**• The details of the assumed filter make a big difference as well • I picked this very gentle, 6db stop band filter to prevent this...**For this run, I dropped the Crq=10fF curve**These are 5fF, 2.5fF and 1fF curves recall that Cdet is 3fF for this MPPC 025u • ... how about we lower the HiFreq cutoff and concentrate on the shape of the falling edge. Lets say cut at 100MegHz • So that corresponds to digitizing at 200MSPS**Using SiPMs**Rubinov, WSU HEP seminar Until you have spread your wings, you will have no idea how far you can walk despair.com**CMS**Rubinov, WSU HEP seminar • Two approaches • Straight replacement of the HPD • Coupling individual fibers to individual SiPMs:Electrical Decoder Unit**CMS**Rubinov, WSU HEP seminar**Linearity number of cells is the issue**Rubinov, WSU HEP seminar**EDU**Rubinov, WSU HEP seminar • The EDU • 100% compatible with existing mechanics/optics**CMS**Rubinov, WSU HEP seminar Either of these could use fantastic new devices from Zecotek**MAPDs main characteristics**Ptr=Ptr(V) PDE = QE· eg· Ptr AnfimovNikolay, Dubna, JINR MAPD-3N with deep microwells (n-type substrate) 15 000 pixels*mm-2 MAPD-1 with surface pixels (p-type substrate) 556 pixels*mm-2**ILC- SiD**Rubinov, WSU HEP seminar • For SiD there are two possible uses of SiPM • HCAL : 3x3 cm cells directly coupled to SiPMs • Tail catcher/Muon system with scintilator strips and WLS fibers coupled to SiPMs**Scint HCAL for SiD**Rubinov, WSU HEP seminar The key issue here is coupling of the scintillator to SiPM Northern Illinois University has some very clever and pioneering work on this (basic idea is to put a dimple in the center of the cell) We have made an Integrated Readout Layer board for tests of these cells**SiD muon system**Rubinov, WSU HEP seminar • For SiD muon system there are 3 main issues • Cost • Cost • Cost