Introduction to the physics of the SiPM Angela Intermite Liverpool Group Meeting 28.10.2009

Optical fiber sensor for beam loss monitoring SiPMs Angela Intermite 28.10.2009 2/10 2

Overview What is a Geiger mode avalanche photodiode? How to quench an avalanche? What are the main sources of noise? Dark count Cross talk Afterpulsing Are there some good reasons for preferring SiPM? Angela Intermite 28.10.2009 3/10 3

A reverse p-n junction The operation of a rev p-n junction includes: carrier generation carrier transport and/or multiplication extractions of carriers. Angela Intermite 28.10.2009 4/10

How to quench the avalanche Passive Quenching Advantage - Cheap, very simple circuitry Disadavantage - Slow recovery time Active Quenching Advantage - Very fast transitions Disadavantage - Expensive especially for SiPM with high N Cova et alt. Angela Intermite 28.10.2009 5/10 5

Sources of noise: Dark count Band to band recombination or radiative recombination Trap assisted recombination, also called Shockley Read Hall effect Auger recombination Angela Intermite 28.10.2009 6/10 6

Sources of noise: Cross-talk and Afterpulsing Direct cross-talk Inside the depletion layer. Through reflection Afterpulsing It depends on: Trap concentration in the junction depletion layer number of carriers generated during a Geiger pulse. Angela Intermite 28.10.2009 7/10 7

Some good reasons for choosing SiPM...   VACUUM TECHNOLOGY SOLID-STATE PMT MCP-PMT HPD PN, PIN APD SiPM Photon detection efficiency Blue 20 % 60 % 50 % 30% Green-yellow 40 % 80-90 % 60-70 % 50% Red  6 % 90-100 % 80 % 40% Timing / 10 ph.e  100 ps  10 ps tens ns few ns tens of ps Gain 106-107 106 – 107 3 - 8x103 1  200 105 – 106 Operation voltage 1 kV 3 kV 20 kV 10-100V 100-500V  100 V Operation in the magnetic field  10-3 T Axial magnetic field 2 T  4 T No sensitivity Threshold sensitivity (S/N1) 1 ph. e 100 ph. e 10 ph.e 1 ph.e Shape characteristics sensible bulky compact sensible, bulky robust, compact, mechanically rugged Radiation hardness? Angela Intermite 28.10.2009 8/10

Conclusions Physics of SiPM Quenching circuitry Main sources of noise: Dark count Cross talk Afterpulsing Differences between SiPM, PMT and APD Angela Intermite 28.10.2009 9/10

Thank You !