SiPM Research & Development

SiPM Research & Development Teacher: Mark Kirzeder Student: Emily Lohr Advisors: Dr. Randi Ruchti Mr. Barry Bambaugh

What is a SiPM? • Silicon Photo Multiplier • A new generation of detection system. • An alternative to traditional PMTs.

SiPMs vs. PMTs • Relatively Large • High voltage • Expensive • Non-recoverable • Inconsistent signals • Affected by B fields • Not as precise • Slower response time • Small • Low voltage • Relatively low cost • Recoverability • Signal consistency • Unaffected by B field • Single photon counting ability • Fast response time

SiPM Signals • Individual photon counting ability • Active area • Inactive area

SiPM Drawbacks • Optical cross talk • A signal from one pixel generates a signal in an adjacent pixel • High rates of noise

Objectives • Quantify SiPM performance with respect to • Manufacturer: Sensl vs. Hamamatsu • Number of pixels (active area) • Size: 1mm (square) vs. 3mm (square) • Bias Voltage • Temperature • Determine best configuration for SiPM operation

Experimental Set Up

Experimental Devices Hamamatsu device with electronics for controlling bias voltage Sensl device with electronics for cooling and controlling bias voltage

Experimental Devices • Sensl – Major Focus • 1mm x 1mm square • 35 micron x 35 micron square pixels • 3mm x 3mm square • 35 micron x 35 micron square pixels • Hamamatsu – Minor Focus • 1mm x 1mm square • 25 micron x 25 micron (1600 total pixels) • 50 micron x 50 micron (400 total pixels)

Experimental Set Up • SiPM Location • Light Splitter • For future use when operating 2 SiPMs simultaneously • LED • Red • Pulsed at 50 kcps

Noise Study - Methods • SiPM turned on in the box without the LED • A counter was used to determine number of events that were above a given threshold • Temperatures were tested from +25 oC to -30 oC • Bias voltages were tested from 29.5V 31.5V

Noise & Temp Study – Sensl Results Red = 29.5V, Orange = 30.0V, Yellow = 30.5V, Green = 31.0V, and Purple = 31.5V

Noise & Bias Study – Sensl Results Red = +25C, Orange = +20C, Yellow = +10C, Green = 0C, L. Blue = -20C, D. Blue = -25C, and Purple = -30C

Noise & Bias Study – Hamamatsu Results Red = Ham Electronics, Yellow = 30ns gate, Green = 100ns Gate and Blue = 100ns Gate

Conclusions • 3mm Sensl Device • Noise was minimized at -20 oC • A bias of 30.0 V allows for greatest reduction of noise at -20 oC • 1mm Sensl Device • Noise continued to decrease slightly at -25 oC and -30 oC, although it seems to plateau • A bias of 29.5 V allows for greatest reduction of noise at -30 oC

Signal Quality Study - Methods • LED was used as the trigger • Signals were read into a QVT from the SiPM • Data was then analyzed using a program developed by Barry Bambaugh according to a Poisson Distribution • Identified number of events • Calculated the mean number of photons, peak separation, and number of peaks.

Signal Quality Study - Methods • A desirable signal is one that has • Large average number of photons • Large peak separation • Large number of peaks • Low amount of noise

Signal Quality Study – Results:Average Number of Photons Red = +25C, Orange = +20C, Yellow = +10C, Green = 0C, L. Blue = -10C, D. Blue = -20C, L. Purple = -25C, and D. Purple = -30C

Signal Quality Study – Results:Average Number of Photons Red = 29.5V, Orange = 30.0V, Yellow= 30.5V, Green = 31.0V, and Blue = 31.5V

Conclusions • 3mm Sensl Device • Little difference in photon detection (+/- 0.2) efficiency at all temperatures at 30.0V • Peak separation increases with increased bias • 1mm Sensl Device • Most photons detected at -10 oC • Peak separation increases with increased bias

Future Work • Exact operational conditions will depend on the application of the SiPM • Noise can be reduce drastically with temp • Efficiency can be increased with bias • Bias does affect noise • Operate two SiPMs simultaneously to verify that the LED is unchanged • Experiment with the Hamamatsu devices more thoroughly

SiPM Research & Development