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

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Experimental Setup

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MPPC Single pe observation at room temperature with 1.2 μs effective gate

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Initial Time Resolution Studies

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137 Cs Source spectrum for MPPC (time permitting)

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 1 st 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 Victor Guarino, Argonne Natl. Lab.

Prototype Support Structure Design for a Two Mirror Aplanatic Telescope

R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University

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Experimental Setups

Timing Resolution Single pe, Linearity, Source Spectra 408nm Diode Laser 75ps pulse width

R580 reference PMT

0.1-3.0 Neutral Density Filters

Bias voltage & output to CFD/ADC MEPhI and CPTA SiPM Test Board Timing measurements use output from Ortec 9307 CFD → 25ps/count Phillips 9186 TDC Blue (468nm peak) LED and exponentially-graded filter wheel

50 μm Pixel MPPC 1x1x10mm 2 LYSO

Single pe and Linearity measurements made with correlated double sample-and-hold (Fermilab CDF RABBIT System) . 1.2

μs effective gate. R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University

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MPPC Individual Photoelectron Observation

MPPC Sample 53 operating V = 70.23V

1x1mm 2 effective area 50 μm pixel size 400 total pixels

•

Noise at operating voltage at room temperature is quite low!!

•

Gate of 1.2

μs substantially longer than most other studies

•

Fit has no background! Just sum of 6 Gaussians (pedestal + 1-5 pe).

R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University

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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 1.2

μs

R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University

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Initial Timing Resolution Results (1) – MPPCs

Time Time resolution at highest light levels. Substantial saturation of MPPC 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.

R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University

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Initial Timing Resolution Results (2) – MEPhI E404



Gain ~ 4 x 10 5

R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University

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Energy Spectra from LYSO Background ( 176 Lu) & 137 Cs

Background decays of 176 Lu in 1x1x10mm 3 crystal 200ns 200ns Hamamatsu 25 μm pixel MPPC at V = 78.94V

MEPhI Sample operated at V = 43.0V

R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University

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Energy Spectra from LYSO Background ( 176 Lu) & 137 Cs

Uncalibrated horizontal scales σ/E ~ 9.2% (22% FWHM) Expanded scale from those on left.

Rough absolute zero approximated.

Background spectrum from 176 Lu decays?

R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University

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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 137 Cs and 22 Na Place 4x4 array against LYSO & BGO crystals to study position resolution and depth of 1 st interaction R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University

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Conclusions

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Initial studies indicate good timing resolution with both Hamamatsu MPPC and MEPhI SiPM detectors

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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.

R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University

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Backup Slides Follow

R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University

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Laser Timing

Synch output from laser MPPC output from laser pulse

R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University

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Saturation Measurement of Hamamatsu MPPC

  MPPC 53 -- 50 μm pixel size with 400 total pixels 30000 ADC counts corresponds to 34.3pC. For Gain = 5.65x10

5 , implies about 380 pe. (or fired pixels at full gain) R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University

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25 μm Pixel Size I-V Curve

R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University

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RABBIT Before/After Timing

RABBIT Before/After timing with respect to signal from MEPhI SiPM Blue -

Before

Purple –

After

Yellow –

SiPm signal using LED pulser

R. Wagner, MPPC/SiPM Timing Resolution PD07 Kobe University

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