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sim_pmt - Lab1 Computer Simulation of a Photomultiplier...

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Lab1: Computer Simulation of a Photomultiplier Tube Sharina J. Haynes September 23, 2009 Fabienne Bastien, Erica Morgan ABSTRACT The observation of light is the fundamental tool in astronomy. All of astronomy depends upon the accuracy and precision to which light can be measured and recorded. The electronic detection of light by the photoelectric e?ect is fundamentally limited by sta- tistical uctuations. In this lab, we studied this by simulating a photomulitplier tube (PMT) capable of detecting individual photons. The experiment reveals that the counting of photons is described by Poisson Statistics and that increasing the number of measurements increases the accuracy and precision to which one can know the brightness of a source of light. For this lab we developed a computer simulation of photon detection by a photomultiplier tube. In this experiment, we include the fluctuations in photon arrival and electronic noise that we will refer to ”dark count.” 1. Introduction A photomultiplier tube [PMT] is a sensitive device for measuring photon counts, and is used in wide array of applications. Due to its sensitivity, it is receptive to the number of external parameters (ie) such as electric fields, magnetic fields, and temperature. The PMT also shows a small dark current produced by the thermal emission of electrons from its cathode. We call these dark counts. Light which enters a photomultiplier tube is detected and produces an output signal through the following processes because it operates using the photoelectric effect. (1)Light passes through the input window. (2)Light excites the electrons in the photocathode so that photoelectrons are emitted into the vacuum (external photoelectric effect). (3)Photoelectrons are accelerated and focused by the focusing
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