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

Initial Timing Resolution Results (2) – MEPhI E404

Gain ~ 4 x 105

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

Blue - Before

Purple – After

Yellow – SiPm signal using LED pulser