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According to the exponential distribution, very few particles have a large amount of kinetic energy, but no matter how high the energy or how low the temperature, the population is never quite zero. This means that even processes that require very large amounts of energy will take place in a system in thermal equilibrium at any temperature, given enough time. An interesting test of this theory would be to set up an experiment to look for those rare instances when an ensemble contains a particle with energy many times the average given by the temperature. This experiment has been carried out using a novel detector comprised of a large array of silicon avalanche photodiodes known as a silicon photomultiplier (SiPM). The avalanche photodiode works like a mousetrap, storing a large amount of energy and then releasing it suddenly in response to a weak disturbance. In its intended mode of operation, the weak disturbance is provided by the absorption of a single photon of visible light in the region of the diode junction. In this experiment, the device was shielded from all external light sources, so that the only possible trigger mechanism is the internal motion of electrons within the junction itself. According to the kinetic theory, even without photons to excite the electrons over the trigger threshold, from time to time an electron should acquire enough energy to simulate an absorbing photon just from the randomness of the thermal energy distribution. The rate at which these thermal triggers occur is predicted by the kinetic theory, based on the exponential distribution, the temperature of the junction, and the number of electrons in the region of the junction. This mechanism reacts to the energy of a single electron, allowing us to detect the thermal energies of a single particle.  

According to the exponential distribution, very few particles have a large amount of kinetic energy, but no matter how high the energy or how low the temperature, the population is never quite zero. This means that even processes that require very large amounts of energy will take place in a system in thermal equilibrium at any temperature, given enough time. An interesting test of this theory would be to set up an experiment to look for those rare instances when an ensemble contains a particle with energy many times the average given by the temperature. This experiment has been carried out using a novel detector comprised of a large array of silicon avalanche photodiodes known as a silicon photomultiplier (SiPM). The avalanche photodiode works like a mousetrap, storing a large amount of energy and then releasing it suddenly in response to a weak disturbance. In its intended mode of operation, the weak disturbance is provided by the absorption of a single photon of visible light in the region of the diode junction. In this experiment, the device was shielded from all external light sources, so that the only possible trigger mechanism is the internal motion of electrons within the junction itself. According to the kinetic theory, even without photons to excite the electrons over the trigger threshold, from time to time an electron should acquire enough energy to simulate an absorbing photon just from the randomness of the thermal energy distribution. The rate at which these thermal triggers occur is predicted by the kinetic theory, based on the exponential distribution, the temperature of the junction, and the number of electrons in the region of the junction. This mechanism reacts to the energy of a single electron, allowing us to detect the thermal energies of a single particle.  

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