FAQ 2017-04-27T12:43:30+00:00

FAQ

How to calculate the responsivity 2017-07-24T15:42:27+00:00

The optical sensitivity of SiPM is  typically given by the photon detection efficiency (PDE), which is the ratio of detected photo-electrons and the number of incident photons. This value can be used to calculate the responsivity of the sensor by the following equation:

    \[ {\mathrm{R}= \frac{\mathrm{PDE} \cdot \lambda \cdot \mathrm{G} \cdot e \cdot (1+\mathrm{P_{AP}}) \cdot (1+\mathrm{P_{XT}})}{h \cdot c \cdot 100\%}} \]

  • \mathrm{PDE} = Photon Detection Efficiency
  • \lambda= Wavelength
  • \mathrm{G} = Gain
  • \mathrm{e} = Electron Charge
  • \mathrm{P_{AP}} = Afterpulsing Probability
  • \mathrm{P_{XT}} = Crosstalk Probability
  • h = Planck Constant
  • c = Speed of light

 

 

PM3325-WB-Responsivity

What are the differences between the Evaluation PCB Versions: AS, AX and AR? 2017-05-10T11:45:22+00:00

AR Version

Compatible with PEVAL-KIT-MCX (Optical Bench)

PE33xx-EB-AR Front
MCX Connectors Bias, Signal Out
Readout DC, resistive tap matched to 50 Ω
Typical Applications General purpose, suitable for all applications which only need a single signal output
Recommended for All applications
Pulse Shape Example Pulse shapes of the Signal Output (without preamplifier) when illuminating with a short laser pulse < 1 ns. Please note that due to the DC coupling there is no undershoot of the signal visible. Example shows PE3325-WB-AR with the standard load resistor of 51 Ω on the board. Signal Output of PE3325-WB-AR was directly connected to an oscilloscope with 50 Ω termination.

PE3325-WB-AR-PulseShape

PE3325-WB-AR – PulseShape

AX Version

Compatible with PEVAL-KIT-MCX (Optical Bench)

PE33xx-EB-AX Front
MCX Connectors Bias, Signal Out, Monitor Out – all signal lines are matched to 50 Ω
Readout AC, impedance matched to the preamplifier
Signal Out 90% of the unamplified signal
Monitor Out 10% of the unamplified signal
Typical Applications Simultaneous Timing (Amplified Signal) and Energy Measurements (Monitor) (e.g. Spectroscopy, PET); Using full dynamic range of SiPM: Amplified Signal for Single Photons, Monitor output for higher light intensities (which drive the preamplifier into saturation)
Recommended for Timing critical applications; Applications which need simultaneously two outputs; Applications with a DC offset on the signal
Pulse Shape Example Pulse shapes of the Signal Output (without preamplifier) and the Monitor Output (without preamplifier) when illuminating with a short laser pulse < 1 ns. Please note that due to the AC coupling there is an undershoot of the signal visible. Example shows PE3325-WB-AX but is the same for the AS version. Both Signal Output and Monitor Output of PE3325-WB-AX were directly connected to an oscilloscope with 50 Ω termination.

PE3325-WB-AS-AX-PulseShape

PE3325-WB-AX and -AS – PulseShape

AS Version

Compatible with PEVAL-KIT (Standard)
Electrically identical to AX Version

PE66xx-EB-AS
SMA Connectors Bias, Signal Out, Monitor Out – all signal lines are matched to 50 Ω
Readout AC, impedance matched to the preamplifier
How can I understand the nomenclature of KETEK’s SiPM product description? 2017-05-02T14:31:46+00:00

For single SiPMs, e.g. PM3325-WB:

  • PM = PhotoMultiplier
  • 33 = size of active area, here 3.0 x 3.0 mm²
  • 25 = microcell size, here 25 µm
  • W = package type, here Waver Level Package
    E = Epoxy type package
  • B = SiPM peak sensitivity, here Blue

 

For evaluation PCBs, e.g. PE3350-EB-AR:

  • PE = Photomultiplier Evaluation
  • 33 = size of SiPM active area, here 3.0 x 3.0 mm²
  • 50 = microcell size, here 50 µm
  • E = package type, here Epoxy type package
    W = Waver Level Package
  • A = version number
  • R = type of readout, optical bench, MCX plugs, here Resistive tap, DC coupled
    X = optical bench, MCX plugs, AC coupled
    S = standard version, SMA plugs, AC coupled

 

For SiPM Arrays, e.g. PA3325-WB-0808

  • PA = Photomultiplier Array
  • 33 = size of active area, here 3.0 x 3.0 mm²
  • 25 = microcell size, here 25 µm
  • W = package type, here Waver Level Package
    E = Epoxy type package
  • 0808 – number of SiPMs in x and y direction, here 8 x 8 array
What is the variation of the breakdown voltage in between different SiPMs? 2017-04-27T12:31:52+00:00

A typical breakdown voltage variation between different SiPMs can be found in the plot below, the FWHM is 85 mV. The example shows the variation for the WB Series, but also applies to EB Series SiPMs.

SiPM Breakdown Voltage Variation

Which overvoltage do you recommend for operation? 2017-07-24T15:27:16+00:00

In general, we recommend an overvoltage range of 2.5 to 5.0V. Nevertheless for many applications, an overvoltage between 4.0 and 5.0 V has shown to be some kind of “sweet spot”, where the PDE is very high with still low noise of the SiPMs.

What is the maximum bias overvoltage which should not be exceeded? 2017-04-26T09:13:25+00:00

Usually we recommend to work within an overvoltage range of 2.5 V to 5.0 V. Nevertheless our SiPMs can also be operated at higher overvoltages, depending on the type up to 10.0 V overvoltage. As long as there is a current limit set for the operation, the SiPM cannot be destroyed. Nevertheless please keep in mind that at higher overvoltages also the noise increases.

How is the Peak to Tail (P/T) ratio defined? 2017-04-26T08:50:38+00:00

KETEK specifies the Peak to Tail (P/T) for Mn Kα, as a ratio of Mn Kα to the mean value of the spectrum between 5.26 and 5.32 keV.

How is the Peak to Background (P/B) ratio defined? 2017-04-26T08:32:41+00:00

KETEK specifies the Peak to Background (P/B) for Mn Kα, as a ratio of Mn Kα peak to the mean value of the spectrum between 900 eV and 1100 eV .

I need a custom SiPM solution, standard products do not work for me. Can you help me? 2017-04-25T15:21:25+00:00

We are always willing to fabricate custom SiPMs based on our SiPM technology if there is a business case.
In the past, we did already various custom SiPM products for customers all around the world.

What does “breakdown voltage” mean? 2017-04-25T15:19:14+00:00

SiPMs consist of many small micro-photodiodes, referred to as microcells. They are operated above breakdown in Geiger mode. The term “breakdown voltage” refers to the voltage, above which the gain of the SiPM gets larger than 1 and where the SiPM operation starts.

I need to detect higher energetic X-rays, gammas or particles. Are SiPMs suitable? 2017-04-25T15:08:23+00:00

Yes, SiPMs can be used with the majority of available scintillators. The scintillators converts the high energetic energy deposit into visible light which then can be read out by our SiPMs. We have broad experience in this field and are happy to support you specifically to your application’s needs.

At which wavelengths are your SiPMs sensitive? 2017-04-25T15:15:47+00:00

We recommend using our SiPMs in the wavelength range of 300 nm to 950 nm.

I need a larger quantity of SiPMs. Can you supply it? 2017-04-25T15:04:40+00:00

Yes, definitely. Please contact us directly and we are happy to provide you a quotation.

I am unsure wether SiPMs can work for my application. Can you help me? 2017-04-25T15:00:51+00:00

We are always willing to support you and your application specific needs. we have a team of SiPM application experts ready to assist you and answer your questions. Our priority is to get things running and to make you a happy customer.

Are SiPMs easy to damage or destroy? 2017-05-09T10:56:22+00:00

Actually SiPMs are very robust devices. With the recommended current limits one almost cannot destroy any SiPM. Accidental illumination, daylight illumination or wrong bias voltage polarity usually are uncritical and do not damage the SiPM.

Which bias voltage polarity do you recommend? 2017-04-25T14:49:50+00:00

Our SiPMs work with both positive and negative bias voltage. The bias voltage polarity has no effect on the SiPM’s performance and you are free to choose the suitable polarity for your application.
All our Evaluation Kits and Evaluation PCBs are powered with positive bias voltage

What does the term “overvoltage” refer to? 2017-04-25T14:47:38+00:00

Overvoltage ist the voltage above the breakdown voltage of an SiPM. E.g. in the case of PM3325-WB, the breakdown voltage is 27.5 V. We specify operation up to an overvoltage of 5 V, which in that case would result in an operating voltage of 32.5 V.

What is the recommended maximum current limit for a certain SiPM? 2017-04-25T14:41:48+00:00

For any of our SiPM series, we recommend for PM11 a maximum current limit of 1 mA, for PM33 it is 2 mA and for PM66 is is 5 mA.