KETEK's SiPM data sheets detail key performance parameters of their silicon photomultipliers - a key parameter is Gain which is explained in more detail below.
The Geiger discharge of a microcell is proportional to the applied overvoltage, i.e. ΔV = VBias – VBreakdown and the microcell capacitance.
|Gain = ((CPixel • Δ V) / e) ∝ GE • Δ V|
|CPixel = Microcell Capacitance||ΔV = Overvoltage||GE = Geometric Efficiency||e = Elementary Charge|
When a microcell detects a photon it produces a standardised charge with a very low Excess Noise Factor close to 1.Therefore the gain of a SiPM scales linearly with the applied overvoltage. Typically the gain of KETEK SiPMs is in the range of 105 to almost 107.
This high gain means that even single photon events result in amplitudes of several mV across a 50Ω load.
The graph below shows SiPM gain for KETEK's standard microcell sizes (15µm and 25µm pitch). Gain is linear with overvoltage and is higher for larger cell sizes due to the increase in cell capacitance.