Timing Studies of Hamamatsu MPPCs and MEPhI SiPM Samples Bob Wagner, Gary Drake, Patrick DeLurgio Argonne National Laboratory Qingguo Xie Department of Radiology University of Chicago Topics: Applications and Goals Experimental Setup MPPC Single pe observation at room temperature with 1.2 μs effective gate Initial Time Resolution Studies 137 Cs Source spectrum for MPPC (time permitting)
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Timing Studies of Hamamatsu MPPCs and MEPhI SiPM Samples Bob Wagner, Gary Drake, Patrick DeLurgio Argonne National Laboratory Qingguo Xie Department of.
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Timing Studies of Hamamatsu MPPCs and MEPhI SiPM Samples
Bob Wagner, Gary Drake, Patrick DeLurgioArgonne National Laboratory
Qingguo XieDepartment of RadiologyUniversity of Chicago
Topics:
Applications and Goals
Experimental Setup
MPPC Single pe observation at room temperature with 1.2 μs effective gate
Initial Time Resolution Studies
137Cs Source spectrum for MPPC (time permitting)
2R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University
Applications and Goals
Improved small animal PET scanner– Finer spatial resolution using
MPPC array on crystal(s)• LYSO, LSO, BGO• Combination with differing
decay characteristics to determine depth of 1st interaction
– Good time resolution (< 50ps) of 511 keV γs to provide real time imaging (10 ps resolution ≡ 3mm)
Fine-grained camera for Imaging Atmospheric Cherenkov Gamma-Ray Telescope (AGIS collab in U.S.)
– Optical design reduces aberrations by adding curvature to the camera “plane”. (UCLA collaborators)
– Small feature size photodetectors required
Prototype Support Structure Design for a Two Mirror Aplanatic Telescope
Victor Guarino, Argonne Natl. Lab.
3R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University
Experimental Setups
Timing Resolution
MEPhI and CPTA SiPM Test Board
408nm Diode Laser 75ps pulse width
Bias voltage & output to CFD/ADC
0.1-3.0 Neutral Density Filters
Single pe, Linearity, Source Spectra
Blue (468nm peak) LED and exponentially-graded
filter wheel
R580 reference
PMT
50μm Pixel MPPC 1x1x10mm2
LYSO
Single pe and Linearity measurements made with correlated double sample-and-hold (Fermilab CDF RABBIT System). 1.2μs effective gate.
Timing measurements use output from Ortec 9307 CFD → 25ps/count Phillips 9186 TDC
4R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University
MPPC Individual Photoelectron Observation
MPPC Sample 53 operating V = 70.23V
• Noise at operating voltage at room temperature is quite low!!
• Gate of 1.2μs substantially longer than most other studies
• Fit has no background! Just sum of 6 Gaussians (pedestal + 1-5 pe).1x1mm2 effective area
50μm pixel size 400 total pixels
5R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University
Comparison to Single pe Detection in MEPhI SiPM
Cooled to ~ -15°C using dry ice Same at room temperature
Both measurements using correlated double sampled readout with Before/After effective gate width 1.2μs
6R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University
Initial Timing Resolution Results (1) – MPPCs
Time resolution at highest light levels. Substantial saturation of MPPC
Time
Pulse Height
Attenuation of laser pulse to few pe level. Individual pe evident
No deconvolution of contribution from laser, CFD, and TDC has been done.
7R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University
8R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University
Energy Spectra from LYSO Background (176Lu) & 137Cs
Hamamatsu 25μm pixel MPPC at V = 78.94V
MEPhI Sample operated at V = 43.0V
Background decays of 176Lu in 1x1x10mm3 crystal
200ns200ns
9R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University
Energy Spectra from LYSO Background (176Lu) & 137Cs
σ/E ~ 9.2% (22% FWHM) Expanded scale from those on left.
Rough absolute zero approximated.
Background spectrum from 176Lu decays?
Uncalibrated horizontal scales
10R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University
Future Plans
Building several 4x4 MPPC arrays close-packed. We are upgrading the timing DAQ in laser test stand with TAC/ADC
capable of 10ps resolution. Three studies with arrays:
– Install one test 4x4 array in Argonne/UC TrICE Cherenkov Telescope• Use existing TrICE Front End Electronics for readout• Determine MPPC sensitivity to Cherenkov light from
imaged showers
– Study position resolution with
charge division with 3 MPPC linear
array viewing LYSO crystal
irradiated with 137Cs and 22Na
– Place 4x4 array against LYSO &
BGO crystals to study position
resolution and depth of 1st interaction
11R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University
Conclusions
Initial studies indicate good timing resolution with both Hamamatsu MPPC and MEPhI SiPM detectors
Hamamatsu MPPC has very good performance for low noise We are still very early in our studies but making good
progress. We expect to learn much more in our work over next months with arrays plus work on individual devices both in timing and energy resolution.
12R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University
Backup Slides Follow
13R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University
Laser Timing
Synch output from laser
MPPC output from laser pulse
14R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University
Saturation Measurement of Hamamatsu MPPC
MPPC 53 -- 50μm pixel size with 400 total pixels
30000 ADC counts corresponds to 34.3pC. For Gain = 5.65x105, implies about 380 pe. (or fired pixels at full gain)
15R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University
25μm Pixel Size I-V Curve
16R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University
RABBIT Before/After Timing
RABBIT Before/After timing with respect to signal from MEPhI SiPM