Scintillator based detectors for Calorimetry and TimeofFlight PET P Lecoq E Auffray S Gundacker CERN Geneva Switzerland This work is supported under the ERC Grant Agreement N338953TICAL ID: 396321
Download Presentation The PPT/PDF document "Ultimate Time Resolution in" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Ultimate Time Resolution in Scintillator-based detectors for Calorimetry and Time-of-Flight PET
P. Lecoq, E. Auffray, S. GundackerCERN, Geneva, Switzerland
This
work
is
supported
under
the ERC Grant Agreement N°338953–TICALSlide2
TOF forParticle IDPileup mitigation at
high luminosity collidersImprove pattern recognition in Cerenkov detectorsCerenkov/Scintillation differentiation (Dual Readout Cal)Bring additional information on the shower
development in a segmented calorimeterCurrent state of the art for TOF in Alice expt: 75psMajor advances in detector/enabling technologiesFast and high light yield scintillatorsSiPMs, MCPsFast low noise FE electronics (NINO)A 4D imaging HHCAL is within reach
Why
fast
timing in HEP?Slide3
Why fast timing in PET?TOF for
rejecting background events (event collimation)Requires 200ps TOF resolution for a few cm ROI (EndoTOFPET-US FP7 project)TOF for improving image S/NRequires 100ps
TOF
resolution for x5 S/N improvement, which brings a potential sensitivity gain (dose reduction) TOF for direct 3D informationRequires 20ps TOF resolution for 3mm resolution along LOR TOF for restoring image quality for limited angle tomographySlide4
State of th Art: CTR
with NINO chip (Time over Threshold)Slide5
Influence of
crystal
length on CTRS. Gundacker et.al., NIMA, dx.doi.org/10.1016/j.nima.2013.11.025Slide6
CTR distribution of 168 Modules (4x4 cells each)
, 2688 LORsThe bias voltage applied to each module is fixed to 2.5 Volt over breakdown Voltage.Same
threshold
and temp for all channelsState of the art: EndoTOFPET system performance
239 ps
NINO
ASIC
4x4
cells
3.5x3.5x15mm
3
crystals
80
m
m 3M ESR gap
Discrete
Silicon-through-via
(TPV) MPPC
array
Hamamatsu (S12643-050CN)
3x3mm
2
, 0.6mm gap
To be compared to ≈
550(350) ps
on commercial systemsSlide7
The detection chain
q2
SiPM
Crystal
electronics
g
D
t
t
kth
pe
=
D
t
Conversion
depth
+
t
k
’ ph
Scintillation
process
+
t
transit
Transit time
jitter
+
t
SPTR
Single photon
time
spread
+
t
TDC
TDC
conversion time
Random
deletion
1
Absorption
Self-absorption
Random
deletion
2
SiPM
PDE
Unwanted
pulses 2
DCR
Unwanted
pulses 1
DCR, cross talk
AfterpulsesSlide8
Modeling the whole chain
SiPMS. GundackerThesis, CERN, Feb2014Slide9
Analog vs Digital approachCramer-Rao lower bound
Under investigation in the frame of the FP7 EndoTOFPET-US projectwith the Philips digital evaluation kit recently ordered
S.
GundackerThesis, CERN, Feb2014Slide10
Parameters of interest to improve timing resolution
CTR improves like SQRT (photon time density)
Rise time influence
limited by SPTR (66ps)Parameters for LSO: Ce, Ca and Hamamatsu S10931-050P MPPC Slide11
Factors influencing scintillator time resolution
Besides all factors related to photodetection and readout electronics the
scintillator
contributes to the time resolution through:The scintillation mechanismLight yield, Rise time, Decay time P. Lecoq et al, IEEE Trans. Nucl. Sci. 57 (2010) 2411-2416
The light transport in the
crystal
Time
spread
related
to
different
light propagation modes
The light extraction
efficiency
(LY
LO)
Impact on
photostatistics
Weights
the distribution of light propagation modesSlide12
Influence of prompt photons2x2x3mm3 LSO:Ce
, Ca with 70ps rise timeand an arbitrary number of prompt photons generated Slide13
Light
generation in scintillators
Rare Earth
4f5dSlide14
Wide emission spectrum from UV to IR
Ultrafast emission in the ps rangeIndependant of temperatureIndependant of defectsAbsolute Quantum Yield
Whn/Wphonon = 10-8/(10-11-10-12) ≈ 10-3 to 10-4 ph/eh pairHigher yield if structures or dips in CB? Interesting to look at CeF3Hot
intraband
luminescence
More details in SCINT2013 paper
TNS-00194-2013
M.
Korzhik
, P. Lecoq, A.
Vasil’evSlide15
Photon propagation time spread
x
L
with
q
1
0
q
2
q
c
For L = 20mm LSO (
n
= 1.82)
n
grease
= 1.41
q
c = 50.8°
q2
D
t
max
=
71
ps
for
x
= L
D
t
max
= 384
ps
for
x
= 0
Photodetector
gSlide16
Photonic crystals
Crystal
Crystal- air interface with
PhC grating:θ>θcTotal Reflection at the interface
Extracted Mode
θ
>
θ
c
Nanostructured
interface
allowing
to couple light propagation modes
inside
and
outside
the
crystal
air
θ
>
θ
cSlide17
Use large LYSO crystal: 10x10mm2 to avoid edge effects
6 different patches (2.6mm x 1.2mm) and 1 (1.2mm x 0.3mm) of different PhC patterns
0°
45°
Photonic
crystals
increase
the light extraction
efficiency
A.
Knapitsch
et al, “Photonic crystals: A novel approach to enhance the light output of scintillation based detectors, NIM A268, pp.385-388, 2011Slide18
Regular LYSO
a)
Extract more photons at first incidence with
PhC
= better timing
b)
Photonic
crystals
compress
the light propagation modesSlide19
ConclusionsStandard scintillation mechanisms are
unlikely to give access to the 10ps rangeA number of transient phenomena could generate ps measurable signals Photonic
crystals improve scintillator timing resolution by two means:By increasing the light output and therefore decreasing the photostatistics jitterBy redistributing the light in the fastest propagation modes in the crystal