Free · Physics models
SiPM Charge Responsivity Approximation
Estimate charge responsivity from photon detection efficiency, wavelength, gain and first-generation correlated pulse terms.
- Formula & worked example
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Calculator inputs
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How to use this calculator
- Enter the known values in the units shown. Results update as you type.
- Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
- Use the worked example to check the method. Reset restores the starting fields.
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Formula and method
For 25% PDE, gain one million and 500 nm light, the zero-correlated-pulse estimate is about 100,819.3 A/W.
R = PDE × G × eλ/(hc) × (1+PAP)(1+PXT).
Worked example
Enter these known values and leave the other values blank.
- Gain (G)
- 1000000
- Afterpulsing probability (P==AP==)
- 0 %
- Crosstalk probability (P==XT==)
- 0 %
- Wavelength (λ)
- 500 nm
- Photon detection efficiency (PDE)
- 25 %
- Approximate charge responsivity
- 100819 A/W
Assumptions and limitations
- This is a low-light charge-responsivity approximation. Gain counts electrons per primary avalanche, and PDE is the fraction of incident photons causing a primary avalanche.
- The (1+PAP)(1+PXT) terms account only for a simplified first-generation correlated-charge excess. They are not a full branching-process, recovery-time or gate-dependent detector model.
- Afterpulsing and crosstalk are noise processes; their extra charge must not be interpreted as improved intrinsic PDE. Use zero values to isolate the primary response.
- PDE lies between zero and 100%, excluding zero for the retained finite inverses. Correlated probabilities lie between zero and 100%; wavelength and gain are positive.
- Exact SI e, h and c set the conversion coefficient. Detector saturation, finite pixel count and electronic bandwidth are omitted.
- Enter known quantities and leave the unknown blank. Editable quantities support inverse solutions and locks; inconsistent locked quantities are reported. Unit selectors convert the quantity independently of its display.
- Reviewed hash-pinned model correction: This is a low-light charge-responsivity approximation. Gain counts electrons per primary avalanche, and PDE is the fraction of incident photons causing a primary avalanche. The (1+PAP)(1+PXT) terms account only for a simplified first-generation correlated-charge excess. They are not a full branching-process, recovery-time or gate-dependent detector model. Afterpulsing and crosstalk are noise processes; their extra charge must not be interpreted as improved intrinsic PDE. Use zero values to isolate the primary response. PDE lies between zero and 100%, excluding zero for the retained finite inverses. Correlated probabilities lie between zero and 100%; wavelength and gain are positive. Exact SI e, h and c set the conversion coefficient. Detector saturation, finite pixel count and electronic bandwidth are omitted. Enter known quantities and leave the unknown blank. Editable quantities support inverse solutions and locks; inconsistent locked quantities are reported. Unit selectors convert the quantity independently of its display.
Common questions
Do correlated pulses increase intrinsic PDE?
No. They increase collected avalanche charge as a noise contribution. PDE describes primary photon detection.
What does zero afterpulsing and crosstalk mean?
It removes the modeled correlated-charge excess, leaving responsivity from primary PDE, gain and photon energy.
How do I use the inverse calculation?
Clear the quantity you want to find and enter the remaining known values in their selected units. The model can only solve branches with enough independent information.
References
- Hamamatsu: primary detection and correlated pulses
- NIST: exact SI photon and charge constants
- Calculation definition and unit reference
Use exact SI e/(hc) for charge responsivity. Correlated pulse terms are a first-generation multiplicative approximation, not intrinsic photon detection efficiency. Enforce the documented finite physical branch and inverse domains.