![]() Accelerated by this field, the electron acquires enough energy to produce ion/ electron pairs that will also ionise the gas, creating pairs this is the avalanche effect (4). ![]() When the electron arrives close to the mesh (3), it enters an intense electric field (typically on the order of 40 kV/cm in the amplification gap). ![]() But here, within an electric field in the order of 400 V/cm the electron will drift (2) toward the amplification electrode (the mesh) and the ion toward the cathode. When no electric field is applied, the ion/ electron pair recombines and nothing happens. While passing through the detector, a particle will ionise the gas atoms by pulling up an electron creating an electron/ ion pair (1). The micro-mesh is the key element since it allows, at the same time, a high gain of 10 4 and a fast signal of 100 ns. In a Micromegas detector, this gas volume is divided in two by a metallic micro-mesh (“Micromesh” on the schematic) placed between 25 μm and 150 μm of the readout electrode ( Strips on the schematic). The Micromegas detector detects particles by amplifying the charges that have been created by ionisation in the gas volume. In experimental physics, the particle is usually coming from a particle accelerator but it can also come from space ( cosmic ray), from a nuclear reactor or a radioactive isotope. ![]() Working principle of a Micromegas detector.Ī particle detector is used to detect a passing particle and obtain information such as its position, arrival time and momentum. ![]()
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