Report on SiPM Tests

•SiPM as a alternative photo detector to replace PMT.•Qauntify basic characteristics•Measure Energy, Timing resolution•Develop simulation code to confirm measurement.

Test Setup

Two SiPM sitting on top of tables.Hamamatsu SiPM.1x1mm2 area( fill factor : 30%).1600 pixels.

Bias Voltage : 71VNa22 for gamma sourceLYSO : 1x1x10mm3Lecroy 612A amplifier( 10X gain)

Gain vs Bias V( 25um pixel SiPM)

• Consistent with using the fast scope.• Factor ~2 increases in 70.1 and 71.9V.• Similar tendency as in the Hamamatsu Spec.(right figure)

Dark count rate(25um pixel SiPM)

Noise due thermal excitation.

Two discriminators:Threshold : 0.5 and 1.5 p.e.

Vary Bias 70.1 ~ 71.9V.

Read-out count rate.Lecroy 2551 100Mhz scaler.

Single p.e. rate is dominant.

Energy Resolution

Lecroy 2249 ADC25~28% in FWHM

Coincidence Timing Resolution

Lecroy 2228A TDC

Select eventsAround 511keV

~960ps in FWHM(~41ps/bit)

Plans

•Measurement with different type of SiPM and crystal.•Connect signal to Multi-threshold board. •Refine setup to improve results.•Validate simulation code by experimental data.

Geant4 Simulation

•To confirm experimental results.•Data for validation. SiPM Test R9800 PMT+ LSO Crystal•Basis for future detector design study.

Simulation Setup

Pair of LSO + R9800PMTLSO( 6.25x6.25x25mm3)Wrapped with teflon tape.5cm distance between modules.

Borosilicate GlassMetal photocaothode inside Glass

Geant4 with Optical Physics Processes.(Light refraction, reflection, absorption…)Light Yield : 30,000/MeV (LSO)

# of photons detected

Experimental data using Fast oscilloscopeIntegrated charge under pulse shape.

Simulation results.# of photon detected at photocathode.PMT Q.E included.

Timing simulation

Top left: Photo arrival time at photocathode from generation.Top right : Convolution with gaussian for each photon.Bottoms : Rising edges for two modules A and B( arbitrary unit)

Timing simulation

T0 was extracted from linear fit.Time difference between two T0.

~250 ps in FWHM.c.f) ~300ps with real data

Plans

4cm X 4cmx1cm LSO crystal is available.Can be coupled to MCP.

Under test with 4 PMTs block.It’s working.Simulation study.