Sensors scintillation counter

After each series of experiments with beams of various intensity the section plate would be removed from the cell and disassembled, with radioactive silver washed out by nitric acid. Radioactivity of the solutions obtained was measured by a multichannel spectrometric scintillation y-counter with sensitivity of up to 10 G, i. e. around 10 of atoms which, according to calculations, is 10 times lower than sensitivity of ZnO sensor 10 G or 10 of Ag atoms respectively [28]. This difference in sensitivity lead to great inconveniences when exposing of targets was used in above methods. Only a few seconds were sufficient to expose the sensor compared to several hours of exposure of the scintillation counter in order to let it accumulate the overall radioactivity. It is quite evident that due to insufficient stability during a long period of exposure time an error piled up. 

An expensive method is the use of nuclear radiation to obtain information on the level in an apparatus. The nuclear sensor is mounted at one side, and at the other side a scintillation counter is fixed near the surface of the apparatus. Both systems are sheathed with lead-screen shields to give protection from nuclear radiation. A continous level indicator using nuclear radiation is very complicated and therfeore seldom applied. 

Scintillation counter The sensor, the so-called scintillator, contains a transparent crystal that fluoresces when hit by ionizing radiation, thus a scintillation counter measures ionizing radiation. Light emitted from the crystal is measured by a sensitive photomultiplier tube which is attached to an electronic amplifier in order to count the amplitude of signals produced by the photomultiplier. Liquid scintillation counters are a very efficient and practical way to measure and quantify p radiation (see Figure 10.5b). 

The semi-conductor transducer (scintillation counter). Each X-ray photon increases the conductivity of the active zone (the junction) of a lithium-doped silicon diode (one electron for around 3.6 eV). The background noise is reduced if the sensor is maintained at low temperature (cooled by liquid nitrogen or a Peltier device). The entry surface is protected by a beryllium film of a few pm (transparent for Z > 11) (Figure 12.8). In one or other cases the impulse furnished by the detector allows to go back to the energy of the incident photon. 

Electrical and chemical detection systems have also been employed. In addition, radioactive labelling of water and its subsequent detection with a liquid scintillation counter have been demonstrated. ASTM F1249 uses an infrared sensor [55]. 

The laboratory-based eiqieriments for sensor development placed the sensor flow cell within die detection zone of a commercial flow dirough liquid scintillation counter, using the photomultiplier tubes of this instrument to detect... 

Instruments for measuring ionized radiation typically include a sensing device and a readout device. Some are usefiil for field measurement whereas other combinations come in small packages useful for dosimetry. Sensors are very critical. Different types of radiation require different types of sensors. Sensors include Geiger-MueUer tubes (used in Geiger counters), ionization chambers, luminescent detectors, scintillation detectors, and photographic emulsions. 

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