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%) pixels. Bias Voltage : 71V Na22 for gamma source LYSO : 1x1x10mm3 Lecroy 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 Mhz scaler. Single p.e. rate is dominant.

Energy Resolution Lecroy 2249 ADC 25~28% in FWHM

Coincidence Timing Resolution Lecroy 2228A TDC Select events Around 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 + R9800PMT LSO( 6.25x6.25x25mm3) Wrapped with teflon tape. 5cm distance between modules. Borosilicate Glass Metal 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 oscilloscope Integrated 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.