Difference between revisions of "Silicon Photomultiplier Performance"
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Revision as of 15:49, 17 April 2007
PDE measurements of Sensl 1mm devices (E. Smith)
The following numbers are taken from the first two rows of Zisis talk at the collaboration meeting (p 5, 1x1 mm2 SiPM parameters)
| Design | Pixels | DR @ 4V | Fill Factor | Dark Current | Peak PDE @ 4V |
|---|---|---|---|---|---|
| (MHz) | (%) | (μA) | (%) | ||
| C20 | 620 | 2.9 | 17 | -2 | 8.5 |
| A20L | 920 | 5.9 | 34 | -3 | 17.0 |
From Carl's talk (p 37, QE and PDE), you can determine the ratio of the PDE@4V to PDE@1.2V, which was the chosen operating point for Carl's measurements. The ratio is approximately 2. Therefore, the expected PDE@1.2V for the C20 is about 8.5/2 = 4.2. Carl measured it to be 4.4 ± 0.5.
Conclusion: At the operating point of about 1.2 V above breakdown, the PDE for the C20 (1mm2, 17% fill factor) SiPM is about 4.5%. So far, our experience tells us that the practical operating point for these devices is about 1V over voltage. As the voltage above the breakdown increases further signal to noise decreases and even pulse shape become distorted.
If we use the A20L instead of the C20, the PDE will double, but so will the dark rate. We believe that the estimated 110MHz rate for the 4x4 array is for the 1V over voltage, thereby consistent with a PDE of 4.5%.
Comments are welcome. In particular, it would be useful for Richard to remind us the conditions that were used for his measurements of the PDE for the 1x1 and 2x2 mm2 SiPMs. -Elton Smith
