nicola dascenzo, erika garutti, martin göttlich university of hamburg – desy hans-christian...
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Nicola D’Ascenzo, Erika Garutti, Martin Göttlich
University of Hamburg – DESY
Hans-Christian Schultz-Coulon, Alexander Tadday
University of Heidelberg
Application of novel Silicon-based photo-detectors to calorimetry and medical physics
calorimeter
tracker
MPPC
1 Nov. 2007 Erika Garutti - IEEE 2/13
Electron
Hole
The Multi Pixels Photon Counter(from Hamamatsu)
# Pixels (size mm2)
Pieces Bias Dark Rate
>0.5pixels
Dark Rate
> 1.5 pixels
Gain
(10^5)
400 (1x1) 5 76 V 220-250 kHz 9-10 kHz 7.4- 7.5
1600 (1x1) 5 78 V 50-60 kHz 0.05-0.1 kHz 2.6-2.7
3600 (3x3) 5 70 V 3.2-3.3 MHz 320-330 kHz 7.4-7.5
Blue sensitive device:ideal for direct r/o of plastic scint. and crystals
1x1 mm2 active area
3x3 mm2 active area
The MPPC is a multi-pixel avalanche photo-diode operated in Geiger mode
PET application
calorimetryapplication
1 Nov. 2007 Erika Garutti - IEEE 3/13
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MPPC characterization
measured at university of Shinshu (see talk S. Uozumi, N41-4)
intrinsic recovery time of MPPC ~ 4 ns
response curve to a 50ns long light signal
dynamic range artificially extended for long signals due to fast recovery time
MPPC 1600pix has ~ 6000 effective pix. for 50ns long signal
1 Nov. 2007 Erika Garutti - IEEE 4/13
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Application in HEP calorimeters
Task: readout of active layers of highly-segmented and granular calorimeter
Single calorimeter cell readout with SiPM
3x3 cm2 x 0.5 cm thick
prototypeactive layer100x100 cm2
DATA CALICE test beamCERN 2007
Requirements to photo-detector:
• insensitive to B-field (~ 5T)• couple to organic scintillator (green/blue)• low noise (dark rate + cross talk above thresh.) ~ 10-4
• detection eff. for Minimum Ionizing Particles* >95% light yield for MIP ~10 pixels
• dynamic range ~ 100-500 MIP
* one MIP in 0.5 cm scintillator ~ 10000 ( · WLS eff ~ 200 on SiPM)
~8000 SiPMoperated
see talk by F. Sefkow, N13-5
Erika Garutti - IEEE 5/13
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Readout of plastic scintillators with MPPCstudy driven by calorimetry applications for a ILC detector
R&D: direct r/o of scintillator tiles 3x3x0.5cm3
Scintillator tile (Uniplast, Vladimir RU) + Green wavelength shifter fiber (Kurakay)
Present statusSiPM 1056 pixels(MEPHI/Pulsar, RU)green sensitive
3 cm
MPPC directly coupled
response to Ru106 source
MPPC 1600 px
operation point
lig
ht
yie
ld [
pix
els/
MIP
]
MIP
Vbias - Vbreakdown [V]
LY sufficient for calorimeter applicationbut higher LY would allow thinner tiles (lower cost)
w WLS fiber
direct r/o
1 Nov. 2007 Erika Garutti - IEEE 6/13
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Cut at 3 KHz
400 px
1600 px
Readout of plastic scintillators with MPPCMIP collection efficiency
threshold at 1.5 pixdark rate < 3 kHz
noise spectrum
MIP spectrum
MIP detection efficiency > 97%for all r/o combinationscomparable with present status
larger dynamic range than at present
ILC requirement dark rate < 300 HzMIP eff ~ 95%low but acceptable
w WLS fiber
direct r/o
1 Nov. 2007 Erika Garutti - IEEE 7/13
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Hole
Application in PET detectorsreduction of background
Task: identify back-to-back scattered 511 keV photons from e+e- annihilation suppress background and determine true line of response
Background events
remove Compton-scattered with good energy resolution
remove combinatorial bg by ToF meas.
t = 500 ps
1 Nov. 2007 Erika Garutti - IEEE 8/13
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Readout of scintillators crystals with MPPCstudy driven by possible PET applications
* Lutetium OrthoSilicate from Heilger Crystals** Lutetium Fine Silicate from Lebedev, Moskow
2 x scintillator crystalsLSO*: 1x1x15 mm3
3x3x15 mm3 LFS**: 3x3x15 mm3
emission: ~420 nmdecay time: ~40 ns
Teflon wrapping
2 x MPPC1x1 mm2, 400 pixels3x3 mm2, 3600 pixels
coupled with optical grease
Na22 source
• due to high MPPT gain (7.5x105) no amplification needed simple readout• energy integral on VME QDC (Lecroy 1182)• time resolution measurement: 4 GHz Oscilloscope, 50 ps resolution (Textronix TDS7404B)
1 Nov. 2007 Erika Garutti - IEEE 9/13
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• LSO and LFS similar performance (within syst. uncertainty of ~ ± 2%)• Result comparable with typical value for LSO crystals + PMT is E/E ~ 10 % @ 511 keV
Readout of scintillators crystals with MPPCEnergy resolution
MPPC 400
LSO Crystal
1x1 mm2 system 3x3 mm2 systems
MPPC 3600
~ 8% for LSO negligible blue sensitivity
! after 4 months of test E resolution ~ 13±2% degradation of MPPC package or crystal surface ?
1 Nov. 2007 Erika Garutti - IEEE 10/13
Electron
Hole
Issue of MPPC saturation
integral of 511 keV signal ~ 2000 p.e.
! but: signal width ~120 nspeak amplitude ~ 400 p.e.
below saturation estimated at > 10000 pix. for 3600 pix. MPPC and 120 ns signalbut MPPC response non-linear everywhere (see talk N18-2, K.C. Burr)
3600 pix. MPPC coupled to 3x3x15 mm3 LSO crystal
QDC spectrum
scope signal
1 Nov. 2007 Erika Garutti - IEEE 11/13
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Readout of scintillators crystals with MPPCTime resolution
Procedure for time resolution measurement:0. store two waveforms from scope if amplitude > noise level (~ 2mV or ~10 pixels)1. apply energy cut to exclude Compton background 2. define a timing threshold to measure time difference between signals
tcut
2.
two waveforms from the photon peakthe voltage of the two MPPC is tunedto give same response to 511 keV
Npe1.
1 Nov. 2007 Erika Garutti - IEEE 12/13
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Time resolution: result
• Npe = ± 1 of photon peak• ~10-15% of collected events used
for lowest threshold FWHM ~ 650 ps limited by scope noise
*no Jitter analysis package used for this analysis
Background
# ev
ents
time difference [ns]
2 photon-peak amplitudes
Compton background
Photoelectric
fix threshold discr.
Constant fraction discr.
threshold [pixels]
1 Nov. 2007 Erika Garutti - IEEE 13/13
Electron
Hole
Conclusions
• MPPC 400 and 1600pix very good candidates for highly-granular calorimeter:
- direct coupling to plastic scintillator
- LYMIP ~ 7 (10) p.e. with direct coupling (WLS fiber mediated coupling)
- satisfactory MIP detection efficiency with required noise cut
• MPPC 3600 pixels excellent performance for PET application:
- E resolution comparable to PMT
- t resolution < 650 ps (noise limited) next step: build 2 matrices of 6x6 MPPC
with individual readout to test homogeneity, stability, reproducibility,
calibration, multi-channel system
6x6 MPPC 3600
6x6 LFS crystals 3x3x15 cm3
we would like to thank Hamamatsu
for providing the MPPC samples for this study