Jie's Introduction
There is a need for a new and innovative photon detector that can replace the photomultiplier tube (PMT) in particle-physics experiments. This photon detector has to fix the shortcomings of the PMT, yet retain the advantages that the PMT provided. If such a photon detector could be found, it would revolutionize the way photons are detected in high energy physics and could influence the design and structure of particle accelerators themselves.
The new photon detector fixes the primary flaws of the PMT, namely its large size and its sensitivity to magnetic fields. The Silicon Photomultiplier (SiPM) uses a completely different method of detecting photons.
[Insert 2 pictures comparing the two different methods of detecting photons]
Instead of using a series of dynodes to amplify the signal of the photon, the SiPM uses 2 highly charged electron plates that are placed closely together. When a photon lands on one of the plates, the energy in the photon dislodges one of the electrons on the charge plate which releases the energy built up in the plates, causing a pulse. This method of detecting photons makes it impervious to the strongest of magnetic fields because the entire process happens magnetically. The PMT, on the other hand, needs the electron to travel a certain trajectory, therefore making it very susceptible to magnetic fields. If the electrons in the PMT veer off from their course due to magnetic fields, then they won't make it to the next dynode and produce a pulse. Also, since the inner workings of the SiPM are all electrical, it is possible to make it much smaller in size, compared to the PMT, which requires a vacuum tube.
With these two primary advantages of the SiPM over the PMT, the SiPM could be a suitable replacement as the leading photon detector in particle physics.
While the SiPM has certain advantages over the PMT, it must also be clear that it can perform acceptably in situations where the PMT excels. One such attribute is the PMT's resistance to temperature. The PMT performs at the same rate at almost any temperature as long as it don't melt. In contrast, the semi conducting material used to make the SiPM depends heavily on the temperature that it operates at. A higher temperature will make the SiPM much more likely to produce a pulse, and in consequence, have many more false detections. The rate of these false detections, when occur due to the presence of thermal energy in the SiPM, is called Dark Rate.
The effect temperature on the Dark Rate of the SiPM must be examined to determine the range of temperatures that the SiPM can opperate efficiently. It would also narrow down an optimal temperature in which the SiPM can detect reliably with the lowest dark rate.