* Question
| The output noise of the photomultiplier tube limits its detection of weak light. What are the main types of noise? |
* Answer
| (1) Shot noise This noise comes from the random fluctuation of the photoelectron emission and multiplication process, which is usually called “signal internal noise”.
(2) Dark current noise Dark current is the current that is output when the PMT is placed in a completely dark environment and the operating voltage is applied. (3) Ion noise The ions or feedback ions in the PMT are incident on the photocathode, and the photoelectrons are also excited.In addition, cosmic rays can also cause photoelectron emission from the photocathode, which can also cause noise. |
COMMENTS