Detector ionization

The detection and quantitation of nuclear radiation are based on its interaction with material contained in the detector. Ionization of the gas particles in the... 

Detectors vary in their response to the compounds being sensed, with respect both to the amount and to the class of compound. Since the thermal conductivity of a mixture of two gases (the carrier gas and the sample) is not necessarily a linear function of composition, absolute quantitative measurements with thermal-conductivity detectors can only be obtained after calibration with standard compounds. However, response to structurally similar compounds is quite uniform, and reliable, relative, quantitative data can be obtained with this detector. Ionization detectors give a signal that is related directly to the mass or the concentration of the components, and the response is uniform over a broad range of operating conditions these detectors are, therefore, ideally suited for quantitative work. 

Detector Ionization Sample Flow into Sample LOD RSD [%] Application Refs. 

A peculiar feature of flameless oxidation is that it requires recirculation of flue gases above self-ignition threshold (850°C for safety). Below threshold, a burner stabilized flame must be provided (Figure 23.9) and this is carried out by a system capable of selecting between flame mode (the only possible mode below 850°C) and FLOX mode (above threshold both modes are possible). Below threshold, a flame detector (ionization or UV principle) is required if FLOX is selected above threshold, then the flame detector must be neutralized (because there is steady combustion without flame). Dedicated control units have been developed for this purpose [1] the overall operation of the control system should be carefully checked in operating conditions. 

Smoke detectors (ionization) Detects smoldering fires Low cost Easily contaminated Affected by the weather Indoor use... 

Gas-Filled Detectors Ionization Chambers, Proportional Counters, and Geiger Counters... 

As was the case with EDXRF, escape peaks that are detector artifacts occur in WDXRF gas-filled detectors. Ionization of the filler gas by an X-ray photon usually results in the ejection of an outer shell electron. However, it is possible for ionization to occur by ejection of an inner... 

Compounds Matrix Detector Ionization Source Ionization Mode (mg/kg) Reference n CD... 

The vitrified waste canister assay system (VCAS) is intended to determine the residual uranium and plutonium content in canisters of vitrified high-level spent-ffiel reprocessing waste prior to the termination of safeguards on this material. It consists of five neutron detectors (two fission chambers, two U chambers and a bare chamber sensitive to thermal neutrons) and one gamma detector (ionization chamber, meant to authenticate the presence of gamma radiation). In contrast to the VWCC, the VCAS uses fission chambers... 

Many home smoke detectors contain small amounts of radioactive material. The radiation emitted by the material ionizes air within the detector, which in turn produces an electrical current. When smoke from the room enters the detector, ionized air attaches itself to the smoke particles, diminishing the electrical current and setting off the alarm. 

Scintillation Detector Ionization Chamber Geiger-Mueller tube... 

All columns were made in 10ft sections of inch o.d., 0.002 inch wall thickness stainless steel tubing. To avoid fouling the detector ionization source, columns are pre-treated in 200 ml per minute dry flowing nitrogen at 130°C for two days. Chloroform, carbon tetrachloride or acetone must not be used as solvents for the liquid phase due to the extreme sensitivity of the detector for these materials. 

Smoke detectors. These devices detect fires more rapidly than the heat detector, but are more expensive. Smoke detectors are more suitable than heat detectors to protect open areas because smoke from fires will not dissipate as rapidly as heat in a given space. There are two basic types of smoke detectors ionization and photoelectric. Ionization detectors respond more rapidly to open flaming fires, which tend to produce large amounts of small smoke particles, while photoelectric detectors respond best to smoldering fires, which produce larger smoke particles. The ionization smoke detectors are the kind that are most commonly used in homes and apartments. 

Electron-capture detection, a detector ionizes analytes by collision with metastable carrier gas molecules produced by fi-emission from a... 

Flame ionization detector, providing a mass flow dependent signal, the detector ionizes most classes of organic compounds. FID is a universal detection technique. Little or no response have noble gases, CO, CO2, O2, N2, H2O, CS2, NO, NH3, perhalogenated compounds, formic acid/aldehyde. 

Photoionization detector, the photoionization detector ionizes analyte molecules with photons in the UV energy range, provides a concentration dependent signal. The photoionization detector is a selective detector that responds to aromatic compounds and olefins when operated in the 10.2 eV photon range, and it can respond to other materials with a more energetic light source. 

This concept forms the basis for the operation of gas-type ionization detectors (ionization chambers, proportional counters, and Geiger Muller counters) as illustrated in Figure 1. Ionization detectors, as the name implies, make use of the direct ionization of a sensitive volume of gas to measure radiation. A gas-filled volume is placed between two electrodes, one connected to the positive side of a d.c. power supply such as a battery and the other connected to the negative side. Thus, a potential difference is established between the two plates. A sensitive device for measuring current flow is also placed in the circuit. Under... 

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