Transcript Recent news about SiPM R&D in DESY

Recent news about SiPM based
applications R&D in DESY
Nicola D’Ascenzo
University of Hamburg - DESY
Calorimetry at International Linear
Collider
The ILC physics requires a calorimeter with:
1. High granularity (Good jet energy
resolution)
2. Ermeticity and good missing energy
resolution
3. Compactness (The detector has to stay
inside the magnetic coil)
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The scintillator tile hadron calorimeter
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Sampling calorimeter : absorber
stainless steel, active medium plastic
organic scintillator.
Along the magnetic field direction it
extends in
-220 cm < z <220 cm
It covers the detector along the radius in
the region 180 cm< r < 290 cm
The test beam prototype: 1 m3 .
Test beam prototype : 38 layers, 216
channel per layer.
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SiPM: a good photodetector for hadron
calorimetry
The good SiPM for this application:
1. Low noise above the suggested cut
on the mip spectrum (Controlled
dark rate and cross talk)
2. Light Yield not exceeding the
saturation behaviour of the device.
3. Stable and controlled production
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The scintillator direct readout
The direct readout is easier to extend to
a large scale production.
The solution which respects the required bounds
on the parameters:
1. Blue Sensitive?
2. Green sensitive and large?
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The MPPC by Hamamatsu
Blue sensitive Silicon PhotoMultiplier,
Suitable for the direct coupling
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Direct readout with MPPC
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Readout of a plastic scintillator
tile directly and comparison
with the mediated green fiber
Tile wrapped with a 3M
reflector. In case of the direct
readout, only a window of
1mm x 1mm is open in front of
the MPPC
Source: Ru106
Integration gate 80 ns
External trigger
(Photomultiplier tube)
Reproducibility of the
measurement +- 3%
systematic (coupling,
positioning etc ...)
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Direct readout with MPPC : Most Probable
Value of the mip response spectrum
400 px
1600 px
The green dots correspond to the traditional wavelength shifter fiber readout.
The performances of the MEPHI SiPMs used are totally reproduced.
THe blue dots correspond to the direct readout: a good light yield is obtained
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The direct readout with MPPC:
mip collection efficiency
1600 px
Cut at 3 KHz
400 px
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Direct Readout with MPPC: application to
electromagnetic calorimetry
GLD-CAL group, Kobe University
This is the first attempt of using MPPC in the direct readout configuration
in the calorimeter design.
The study of the impact of this technology in the physics reconstruction
is still in progress.
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The direct readout: discussion
• The direct readout looks promising for the
simplification of the design of the calorimeter and
the extension of the concept to a large scale.
• Still some conceptual problems:
– Uniformity of the light response according to the impact of
the particle in the scintillator
• Montecarlo studies and experiments will test this soon
• What is the effect on the performance of the
calorimeter?
– What is the best position for the coupling?
• The blue sensitive MPPC opened good perspectives
to the design of calorimeters: ready to test new
photodetectors.
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Application of MPPC in PET: motivations
and goals
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The calorimeter si just a big PET
machine:
– The hadron calorimeter has milions
of channels
– The hadron calorimeter has a very
high granularity: imaging detector!
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It is only needed to:
– Change scintillator (from organic to
inorganic)
– Change granularity (from 3x3 cm2
to ~1x1 mm2)
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The technology and the needs of
the photodetector are the same !
Energy resolution and timing
measurements
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This study is just at the beginning!
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Application of MPPC in PET:
setup
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2 LSO Crystals of 1mm x 1mm (3mm
x3mm)
Read out by 1x1 mm (3x3 mm)
Hamamatu MPPC
No amplification needed!!!
QDC
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Application of MPPC in PET:
energy resolution
3mmx3mm LSO
crystal
Coupled with a
3mmx3mm
MPPC
Resolution =14 %
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1mmx1mm LSO
crystal
Coupled with a
1mmx1mm
MPPC
Resoultion =20 %
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Application of MPPC in PET:
timing resolution
Cut at 7 photoelectrons
4 GHz Digital oscilloscope used to calculate the time difference (50 ps precision)
Still the system needs to be improved with a lower discrimination.
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Application of MPPC in PET:
discussion
• The application of MPPC in Positron Emission
Tomography looks promising: the blue sensitivity of
the photodetectors is excellent.
• In DESY we will test different combinations of
crystals and photodetectors: YAP, LYSO... With
SenSL, new Hamamatsu ....
• The enrgy resolution measurement will be
continuosly improved in reproducibility and
stability of the system
• Timing measurement (important also for time of
flight) is currently beeing improved.
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After the serious conclusions...
The spin off of the technlogical
developement around the new high
energy
Phyics experiments is very important...
We are dedicating lots of efforts in order
to keep open and fruictful the interplay
between high energy physics and
medical physics.
If we will not find the Higgs Boson, at
least, we can tell we were useful for
something...
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