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Semiconductor detectors are sensing devices that measure radiation levels or particle counts. They may use one element, a line of elements, or a two-dimensional array of detecting elements. The semiconductor detecting material used is only 0.10 mm thick. Semiconductor detectors have very important measurement and imaging applications in different fields, such as special imaging and particle physics.
A silicon detector is commonly used for measuring intensity of radiation or number of ionizing particles in a specific location. The basic principle involved uses a diode, which is a positive (P)-type and negative (N)-type (P-N) junction in reverse bias. The very low idle current of the non-conducting diode becomes the idle reference. When radiation hits the detector, there will be an increase in reverse current that can trigger counters or particle frequency meters that may indicate particle ionization rates.
Microstrip detectors are silicon detectors arranged linearly, and are an expansion of the point detection in diode-type detectors. They are usually made on a base N-type material. By aligning the particle flow with the longitudinal span of the microstrip detector, the path of particles of interest can be confirmed.
Picture elements or pixel detectors are widely used for two-dimensional imaging. Before the invention of pixel detectors, the only way to make use of the ability of X-ray to penetrate and pass through the human body was a barium compound plate, which is commonly known as an X-ray plate. With modern technological capability, pixel detectors allow real-time display of two-dimensional imaging of a part of interest in a medical surgical procedure. Another use could be a real-time display of otherwise hidden material parts, such as in quality assurance.
Particle detectors are available as solid-state semiconductor particle detectors. A particle detector is able to sense the presence of radiation or an ionizing particle. Early particle detectors made use of a sealed tube filled with an ionizing gas. When radiation is present, the gas ionizes and produces a brief moment of increased conductivity.
Security enforcement increasingly relies upon semiconductor detectors. Simple metal detectors that use an electromagnetic field to detect dangerous weapons may be also incorporated with a radiation detector that detects dangerous radioactive materials at security checkpoints. Conveyor belt X-ray machines have increased in importance in rapid inspection of baggage for all types of passengers. The rapid clearing of people entering high-security facilities has also been made possible by the use of semiconductor detectors.
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