P1253297705rdDjf

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CBM Meeting ITEP 05.11.04
SiPM for CBM Michael Danilov ITEP(Moscow)
Muon Detector and/or Preshower
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SiPM main characteristics

• Pixel size 20-30mm
• 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 efficiency
• Optical inter-pixel cross -talk
• due to photons from Geiger discharge initiated by
  one electron and collected on adjacent pixel
• 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 Cpixel50fmF ? Qpixel150fmC106e
• Dynamic range number of pixels (1024)
• ? saturation

42?m
20?m
pixel
h?
Resistor Rn400 k?
Al
R 50?
Depletion Region 2 ?m
Substrate
Ubias
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SiPM Spectral Efficiency

• Depletion region is very small 2mm
• strong electric field (2-3) 105 V/cm
• carrier drift velocity 107 cm/s
• very short Geiger discharge development lt 500 ps
• pixel recovery time (Cpixel Rpixel) 20 ns

• Photon detection efficiency (PDE)
• - for SiPM the QE (90) is multiplied by Geiger
  efficiency (60) and by geometrical efficiency
  (sensitive/total area 30)
• highest efficiency for green light
• ? important when using with WLS fibers
• Temperature and voltage dependence
• -1 oC ? 4.2 in Gain PDEXtalk
• 0.1 V ? 4.5 in Gain PDEXtalk

WLS fiber emission
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Photon detection efficiency ? QE??geom
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SiPM signal saturation due to finite number of
SiPM pixels
Average number of photoelectrons for central
tiles for 6 GeV
Very fast pixel recovery time 20ns For large
signals each pixel fires about 2 times during
pulse from tile
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SiPM Noise
random trigger
noise rate vs. threshold
1p.e.
2p.e.
Ped.
3p.e.
1p.e. noise rate 2MHz. threshold 3.5p.e.
10kHz threshold 6p.e. 1kHz
Optimization of operating voltage is subject of
RD at the moment.
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Experience with a small (108ch) prototype
(MINICAL)
Moscow
Hamburg
SiPM
Tile with SiPM
cassette 3x3 tiles
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Light Yield from Minical tiles (5x5x0.5cm3)
Using triggered Sr source and LED at ITEP
LED
b
N pixel
Using electron beam at DESY (SiPM signals without
amplification)
Good reproducibility after
transportation from Moscow to Hamburg
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LED and 90Sr signals Individual
photoelectrons are clearly seen
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Light Collection Uniformity,
Y11 MC 1mm fiber, Vladimir Scintillator, mated
sides, 3M foil on top and bottom Reduction in
light yield near tile edges is due to finite
size of a b source
Light yield drop between tiles acceptable (Calorim
eter geometry is not projective) Cross-talk
between tiles 2 - acceptable
Light collection efficiency
5x5x0,5cm3
mm
Sufficient uniformity for a hadron calorimeter
even for large tiles Acceptable cross-talk
between tiles of 2 per side Sufficient light
yield of 17, 28, 21 pixels/mip for 12x12, 6x6,
and 3x3 cm2 tiles (quarter of a circle fiber in
case of 3x3 cm2 tile)
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Shower Shape
3 GeV e Black data Yellow -MC
After single tile calibration and smearing MC
describes well shower shape
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NON-LINEARITY and ENERGY RESOLUTION for
DIFFERENT BEAM POSITIONS
For all cases the same fit function is used !
Energy resolution
With universal SiPM calibration curve there is no
differences in response for different beam
positions (different SiPM saturation)
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Cassette, Absorber and Support Structure
Cassette contains 220 tiles with SiPM and
electronics There are 40 cassettes between 2cm
iron absorber Altogether about 8000 tiles of
3x3, 6x6 and 12x12 cm2 with SiPM and individual
readout
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Scan of Strip Using Cosmics Setup
groove depth 2.5mm
LED
cosmics
? Poiss?XtalkG(x0i?x,?0?1 vi)
Center of strip, N pixels (peak) 9.7
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Scan of Strip Using Cosmics Setup (2)
Strip 200x2.5x1cm3
Poisson mean for MIP at normal incidence
MC light yield for 4x1cm2 strip will be 25
smaller.

• In the middle of 280x4x1cm3 strip we expect
  9p.e.
• With threshold 4.5p.e.
• noise rate lt10kHz
• efficiency ?98
• average efficiency gt99

Similar detector - MRS APD - with smaller x-talk
and similar efficiency is under investigation
now. Expect efficiency gt99.5 with noise lt1kHz
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Metal-Resistor-Semiconductor APD (CPTA, Moscow)
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MRS APD Cross-talk
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MRS APD Efficiency vs. Wavelength
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Measurement of Scintillator Sensitivity to
Neutron Background at BELLE
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Backup Slides
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Amplitude Dependence on Temperature
T9.5oC
T14.6oC
T20.1oC
T25.3oC
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Light Yield of Individual MINOS Sc. Strips
There is a substantial difference in individual
strip responce. However all strips give more than
3p.e. at 3m.
Nonuniformity across strip is about 5 only for
4cm x 1cm strips.
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SiPM
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SiPMs will be tested and calibrated with LED
before installation into tiles
(noise, amplification, efficiency, response
curve, x-talk)
PC driven generator
LED driver
Remote control 16 channel power supply
Steering program
DATA BASE
.
gate
Tested SiPM
..
X100
16 ch 12 bit ADC
16 ch amp
16 ch 12 bit ADC
Scheme of test bench for SiPM selection at ITEP
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Tiles will be tested with a triggered ß source
and LED before installation into cassette
Test bench for tile tests at ITEP
16 ch 12 bit ADC
16 chan amps
gate

16 ch remote control power supply
Steering program
b -source
16 sci tile plane
step motor
trigger counter
DATA BASE
movable frame
discriminator
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Emission Spectrum of Y11 WLS Fiber
Measured at distances 10cm, 30cm, 100cm and 300cm
from source.
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(No Transcript)
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Comparison of the SiPM characteristics in
magnetic field of B0Tand B4T (very prelimenary,
DESY March 2004)
No Magnetic Field dependence at 1
level (Experimental data accuracy)
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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