Progress report on SiPM development and its applications TRD2005,Bari,10.09.05 Progress report on SiPM development and its applications Boris Dolgoshein Moscow Engineering and Physics Institute Boris@mail.cern.ch

Single photon Avalance Diodes(SPAD’s): S. Cova et al. ,Appl. Opt

Silicon Photomultiplier (SiPM) TWO STEPS IN DEVELOPMENTS OF GEIGER MODE APD: FIRST STEP: SINGLE PHOTON AVALANCHE DIODE (SPAD), based on single pixel “photon counter” SECOND STEP: from SPAD to Silicon Photomultiplier (SiPM) R 50 h substrate 50 Ubias 46 pixels fired Depletion 1-2m Multipixel (typically ≤ 1 mm2) Geiger mode photodiode with common readout NEXT STEP: Large area SiPM`s from 1x1 mm2 > up to 10x10 mm2 B.Dolgoshein,’Large area SiPM’s…’

SiPM’s have been developed in Russia during last ~10 years(see International Conferences on New Developments in Photodetection ICNDP-1999, 2002,2005) There are four SiPM’s producers for the time being-at the level of test batches production: Center of Perspective Technology and Apparatus CPTA,Moscow MEPhI/Pulsar Enterprise,Moscow JINR(Dubna)/Micron Enterprise HAMAMATSU started the SiPM production last year

SiPM today-reminder: R 50 Ubias Pixel size ~20-30mm Working point: VBias = Vbreakdown + DV ~ 50-60 V DV ~ 3V above breakdown voltage Each pixel behaves as a Geiger counter with Qpixel = DV Cpixel with Cpixel~50fmF  Qpixel~150fmC=106e Electrical inter-pixel cross-talk minimized by: decoupling quenching resistor for each pixel boundaries between pixels to decouple them  reduction of sensitive area and geometrical (packing) efficiency R 50 h pixel Ubias Al Depletion Region 2 m Substrate 20m 42m Resistor Rn=400 k -20M  Very fast Geiger discharge development < 500 ps Pixel recovery time = (Cpixel Rpixel) ~ 20 ns …1mks Dynamic range ~ number of pixels  saturation

3x3mm SiPM parameters Depletion region: appr. 1 m Sensitive area : 3x3 mm2 # of pixels: 5625 Depletion region: appr. 1 m Pixel size: 30 mx30 m Working voltage: 20…25 V Gain: 1…2 x10**6 Dark rate.room temperature: 20 MHz SiPM noise(FWHM): room temperature 5-8 electrons -50 C 0.4 electrons Single pixel recovery time: 1us After pulsing probability: appr. 1% Optical crosstalk: appr. 30 - 50 % ENF: appr. 1.5-2.0(overvoltage dependent)

Spectral dependence of the photon detection efficiency (PDE) for different photodetectors 178nm-5.5%,(1mmx1mm SiPM)

Photon detection efficiency= QE(~80%)x x packing efficiency(active/total area,~40%)x x Geiger efficiency(~70%)

–due to secondary light emitted Optical Crosstalk OC –due to secondary light emitted in Geiger discharge: 10**-5 photons/one electron adjacent pixels are fired- fig’s. OC increases drastically with a Gain becomes >1 for a Gain > few timesx10**7 selfsustening discharge pixel independence and Poisson statistics of fired pixels are violated Excess Noise Factor ENF becomes too large Secondary light: Effective absorption length(Si)- appr. 50 mkm Effective wavelength- appr. 1000 nm B.Dolgoshein,’Large area SiPM’s…’

B.Dolgoshein,’Large area SiPM’s…’

Optical crosstalk,SiPM 1x1 mm2,dark noise Crosstalk==>non-Poissonian distribution: pixel fired/phe=1.7 ENF=1.6 Gain 3x10**6 Crosstalk suppression by special SiPM topology: test structure,PRELIMINARY! Poisson distribution: pixel fired/phe= 0.98+-0.03 ENF= 0.97+-0.05 Gain 3x10**7 B.Dolgoshein,’Large area SiPM’s…’

Recovery time of single pixel: C(pix)xR(pix)-->20ns…..a few mks

Temperature and bias voltage dependence: delta T(V) Gain Signal=GainxPDE -1 C +2.2% +4.5% +0.1V +4.3% +7%

No Magnetic Field dependence at 1% level (Experimental data accuracy) Comparison of the SiPM characteristics in magnetic field of B=0Tand B=4T (very prelimenary, DESY March 2004) LED signal ~150 pixels A=f(G, , x) No Magnetic Field dependence at 1% level (Experimental data accuracy)

SiPM signal saturation due to the limited total number of Sipm’s pixels Response functions for the SiPMs with different total pixel numbers measured for 40 ps laser pulses

Long term stability of SiPM 20 SiPMs worked during 1500 hours Parameters under control: One pixel gain Efficiency of light registration Cross-talk Dark rate Dark current Saturation curve Breakdown voltage No changes within experimental errors 5 SiPM were tested 24 hours at increased temperatures of 30, 40, 50, 60, 70, 80, and 90 degrees No changes within experimental accuracy

SiPM long term stability 20 tested SiPMs worked during 1500 hours Parameters under control: Efficiency of light registration One pixel gain Dark rate Dark current

- + SiPM today: Low noise,high gain Good single electron resolution Very good timing Small recovery time Very low nuclear counting effect Insensitivity to B Simple calibration and monitoring Vow bias voltage Low power consumption Compactness Room temperature operation Good T and V stability Simplest electronics Relatively low expected cost(low resistivity Si,simple technology) Not very high PDE Small area High dark rate(~ area) Exess Noise Factor is large enough due to Optical Xtalk