Post on 31-Mar-2015
Study of Silicon Photomultipliers
Joëlle Barral, MPI, 25th June 2004
Joëlle Barral MPI 25th
June 2004
Study of Silicon Photomultipliers
A. Why SiPM : how to detect good detectors…?
B. From Avalanche PhotoDiodes to Silicon PhotoMultipliers
C. Some Features
Joëlle Barral MPI 25th
June 2004
Why SiPM ?Or how to detect good
detectors…
Caran d’Ache Une planche qui regarde passer le train
High time resolution Short rise time Short recovery time
= FAST DETECTORS
Joëlle Barral MPI 25th
June 2004
High precision Low noise rate Single photon resolution Efficiency
Additional features Low sensitivity to high magnetic / electric field
« low sensitivity to magnetic fields of the order of the gauss »…
Hadron calorimeter : 4T
Behaviour with temperature
Why SiPM ?Or how to detect good
detectors…
Joëlle Barral MPI 25th
June 2004
From APD to SiPM…
Basic structure of an APDImpact ionization releasing EHPs and resulting avalanche multiplication
h+
E
šn+ p
e–
Avalanche region
S.O.Kasap, Optoelectronics
Geiger mode→binary device
Joëlle Barral MPI 25th
June 2004
From APD to SiPM…
Pixels of the SiPM
SiPM
Silicon PhotoMultiplier (SiPM)MEPhI&PULSAR
Each pixel = binary device
SiPM=analogue detector
42 µm
20 µm1 mm
1 mm
24*24=576 pixels
Joëlle Barral MPI 25th
June 2004
Electric field distribution in epitaxy layerTopology of SiPM
From APD to SiPM…Electrical decoupling
to readout the signal
Uniformity of the electric field
Joëlle Barral MPI 25th
June 2004
Features
Energy Gain Single photon resolution Dynamic range
Noise Dark noise Afterpulse Crosstalk
Time Time resolution Rise time Recovery time
Parameters Overvoltage Temperature Light wavelength
(393 nm)→ enough?
Joëlle Barral MPI 25th
June 2004
Gain vs overvoltage
Calibration on the dark noise (cross-talk)
Area on the scope (nVs)
19*1.6*10 *50C Geiger mode :
C = 36 pF
Gain~1.5 106 → low electronic noise
( APD Proportional mode : Gain~200 )
/ | | *( ) / | |pixel pixel pixel bias breakdowngain Q e C U U e
Joëlle Barral MPI 25th
June 2004
Single Photoelectron Counting Poisson statistics?
54 V
A preamplifier is used
52 V 56 V
B. Dolgoshein Int. Conf. On New Developments in Photodetection, Beaune, France, 2002
Joëlle Barral MPI 25th
June 2004
Limited Dynamic Range
• Saturation of the SiPM signal with increased light intensity(Average number of photoelectrons per pixel)
Number of photons arriving on the SiPM
Num
ber
of p
ixel
s fir
ed
Statistics=10 for each number of photons arriving
_
1*(1 (1 ) )photonsN
pixels firedN mm
m=total number of pixels=576
Joëlle Barral MPI 25th June 2004
0 200 400 600 800 1000 1200 1400 1600 1800 2000
700
600
500
400
300
200
100
0
Joëlle Barral MPI 25th
June 2004
B. Dolgoshein The Silicon Photomultipliers in Particle Physics: Possibilities and Limitations
*
_ *(1 )photonsN
mpixels firedN m e
ε=photon detection efficiency
Limited Dynamic Range
Joëlle Barral MPI 25th June 2004
Joëlle Barral MPI 25th
June 2004
_
1*(1 (1 ) )photonsN
pixels firedN mm
m=576
or*
_ *(1 )photonsN
mpixels firedN m e
?
1(1 ) 0.998264
m
1
576 0.998265e
…
Nu
mb
er
of
pix
els
fire
d
Joëlle Barral MPI 25th June 2004
B. Dolgoshein An advanced study of Silicon Photomultiplier
Limited Dynamic Range
1 1.4 1.8 2.2 2.6 3 3.4 3.8
Average number of photoelectrons per pixel
600
500
400
300
200
100
0
Joëlle Barral MPI 25th
June 2004
Limited Dynamic Range
Total number of pixels
Ave
rag
e n
um
be
r o
f p
ho
toe
lect
ron
s p
er
pix
el
20 photons firing
The increase of total pixel number seems technologically possible up to ~4000/mm ²
Hadron Calorimeter
- minimal signal 20 photons/mm²
- maximal signal 5000 photons/mm²
5000 photons firing
Ave
rag
e n
um
be
r o
f p
ho
toe
lect
ron
s p
er
pix
el
Total number of pixels
Irradiance of EUSO (clear sky conditions, primary proton E~1020eV, 45° zenith angle…) = 550 photons/m²
Joëlle Barral MPI 25th June 2004
1
1.4
1
.8
2.2
2
.6
3
3
3
.8
0 400 800 1200 1600 2000 2400 2800 3200 3600 4000
1.7
2
.1
2.5
2
.9
3;3
3
.7
4.1
1200 1600 2000 2400 2800 3200 3600 4000
Joëlle Barral MPI 25th
June 2004
Limited Dynamic Range
Taking into account only the saturation of the pixels…
Nphotons>4056
576 pixels fired
10 %
1 %
Signal dispersionPessimistic…
B. Dolgoshein An advanced study of Silicon Photomultiplier
Relevant ?
22( )photons photonsN incert N
/ : 0.6 346photonsphotons
Nc c N
m
for Si, 400 nm ~70%
* *
*
geom Geiger
photoelectronsgeom
photons
QE
NQE
N
1 2 3 4 5 6Average number of photoelectrons per pixel
Joëlle Barral MPI 25th
June 2004
Limited Dynamic RangeLess pessimistic…
Simulation
-Poisson statistics
-Saturation : incertitude in the number of photons detected
-Fluctuations around the saturation
photonsN
Statistics = 50
0 400 800 1200 1600 2000 2400 2800 3200
600
500
400
300
200
100
0
Number of pixels fired
12
10
8
6
4
2
00 400 800 1200 1600 2000 2400 2800 3200
Joëlle Barral MPI 25th
June 2004
Limited Dynamic Range
Statistics = 1000
2500 firing photons
10%
3700 firing photons
1/ photonsN
Joëlle Barral MPI 25th
June 2004
Rise time
Ubias=56V
One-pixel amplitude~6 V
Rise time~1 ns
FWHM~2 ns
Joëlle Barral MPI 25th
June 2004
Rise timeFHWM~2 ns
Ubias=56V
Rise time~1 ns
~500 pixels fired
APD :rise time=1ns
Joëlle Barral MPI 25th
June 2004
Time resolution
Dependence with the number of pixels fired
Poisson statistics
One-pixel time resolution
σ=17ps
FWHM = 402 ps
σ=171ps
Best time resolution
( 27 ps )
Oscilloscope time resolution
Picosecond Pulsed Diode Laser PDL 800-B :
• Synchronisation Output < 20 ps
Electronics noise
σ/√2=7 ps
Traps in deep levels
_
1
pixels firedN
Joëlle Barral MPI 25th
June 2004
Time resolution
Randomness in physical mechanisms : ultimate limits
Photon absorption in the depletion layer Distance point of absorption / High field region Depth of the depletion layer Position over the active area : transverse propagation of
the avalanche activation (lateral drift and diffusion of free carriers)
Avalanche multiplication = stochastic processFluctuation (number, position) of ionizing events
Joëlle Barral MPI 25th
June 2004
Recovery time Quenching
Passive
Active
Joëlle Barral MPI 25th June 2004
S. Cova et al. Evolution and Prospect of Single-Photon Avalanche Diodes and Quenching Circuits
Difficult for each pixel
Joëlle Barral MPI 25th
June 2004
Recovery time Diode model
Dependence of the overvoltage
1t
RCe
1.2 µs but…Joëlle Barral MPI 25th
June 2004
RpixelCpixel=400 kΩ *36 fF ~ 15 ns
all pixels fired
Joëlle Barral MPI 25th
June 2004
Recovery time
12
12001 1%e
40 ns ?
( It’s bad…)Ubias=56V
Joëlle Barral MPI 25th
June 2004
Recovery time All pixels fired
Limits of the dynamical range Recovery time τ of one pixel
→ τone pixel=1.2 µs
Some pixels fired ?
*(1 )t
m e
Recovery time for one pixel
Joëlle Barral MPI 25th
June 2004
Recovery time
Signal detected (normalized / number of pixels fired)
Delay t between the two firing signals (ns)
63% of maximal value
2*[1 (1 1/ ) ]*(1 1/ ) *[1 (1 1/ ) ] *(1 )photons photons photons
tN N Nm m m m m e
Recovery time = 119 ns
formulasimulation
0 1000 2000 3000 4000 5000
250
230
210
190
170
150
130
Example with two firing signals of 300 photons
Joëlle Barral MPI 25th
June 2004
Recovery time
Number of photons firing ( >264)
Recovery time (ns)
1 *(1 ln[1 (1 1/ ) ])photons
photons
NN pixel m if
>0…
N photons firing = 815
N pixels fired = 436
63%
200 600 1000 1400 1800 2200 2600 3000
1200
1000
800
600
400
200
0
Joëlle Barral MPI 25th
June 2004
Dark noise
Electron-hole recombinations / Carrier generations
Optical electron-hole pair generation
Thermal electron-hole pair generation
Impact ionization
Theoretically impossible in indirect semiconductor
Dark counting rate
@ room temperature
~1 MHz
Joëlle Barral MPI 25th
June 2004
Afterpulsing Time Correlated Carrier Counting
θ=dark-noise rate Trapping levels
* ( )dN
K N tdt
*( ) * j
t
tj
j
P t B e A e
Joëlle Barral MPI 25th
June 2004
Afterpulsing
Hold-off time = 3.4µs
τ1=141 ns τ2=289 ns
τ3=155 ns τ4=393 µs
Probability<10%
Dark counting rate56 V : 1 MHz →1/θ=1 µs
Joëlle Barral MPI 25th
June 2004
Crosstalk
Trenches
1 pixel : 76%
2 pixels : 18% 3 pixels :
5% 4 pixels 1%
1
2
3
Hot carrier luminescence : 105 avalanche carriers→1 photon emitted
1. Direct cross-talk2. Inside the depletion layer3. Through reflection
Dolgoshein Status of upgrade SiPM developments
1 pixel
3 pixels
2 pixels
Joëlle Barral MPI 25th
June 2004
Application : Positron-Emission Tomography 22Na decay : β+ emission Annihilation radiation Coincidence measurement
ep e n
2e e
22Na
γ
511keV
γ
511keV
LSO scintillator 2mm*2mm*10mm
SiPM 1mm*1mm
enough?
Joëlle Barral MPI 25th
June 2004
Application : Positron-Emission Tomography
PET for brain MPI für neurologische Forschung, Köln
Philips, PET, Allegro
Joëlle Barral MPI 25th
June 2004
Application : Positron-Emission Tomography
Compton scattering interaction
Photopeak
Energy windows around the 511 keV photopeaks to :• reduce the chance of fortuit coincidence • cut the spatial dispersion (Compton)
Joëlle Barral MPI 25th
June 2004
Application : Positron-Emission Tomography
σ=1.3 ns
S.R. Cherry Planar APD Arrays for High Resolution PET
σ=2.04 ns
4*4 APD coupled to 2*2*10 mm LSO arrays
Pichler Entwicklung eines Detektors für die hochauflösende PET(…)
σ=1.4 ns
2*8 LSO-APD matrix
Joëlle Barral MPI 25th
June 2004
QUESTIONS ?