Geiger-Miiller counter

Beta-ray emission source and Geiger-Miiller counter... 

Theory Generally, a radioimmunoassay makes use of a radioactive hapten and subsequently the percent of radioactivity bound to the antibody is measured. The radioactivity is determined by the help of a Geiger-Miiller Counter or Geiger-Counter or G-M Tube and sometime by a Scintillation Counter. 

In the case of radioactive isotopes, however, the newcomer in the field is faced with a bewildering array of instruments and manufacturers. Developments in this field have been rapid and papers a few years old probably describe assay methods which are now out of date. Currently there is a vast choice amongst ion chambers, proportional counters, Geiger-Miiller counters, crystal scintillation counters, liquid scintillation counters and semi-conductor counters — all with admirable characteristics for particular purposes. If a worker s interests lie solely in gas chromatographic examination of products then he can obtain a counter specially designed to monitor column effluents. Similarly there are various scanners especially for paper chromatograms or thin layer plates. 

A sample of hemin containing radioactive iron, 59Fe, was assayed with a Geiger-Miiller counter at intervals of time with the following results ... 

Wilkinson, D. H. Ionization Chambers and Counters, Cambridge University Press, Cambridge, UK, 1950. The classic discussion of ionization chambers, proportional counters, and Geiger-Miiller counters. 

The radioactivity of each element is not the same. Each radioactive element undergoes a characteristic rate of decay. It is the intensity of this decay which is determined by a Geiger-Miiller counter. 

Seimiya, T., K. Sekine, and T. Sasaki Counting of tritium with a thin windowed Geiger-Miiller counter tube. J. Scient. Instr. 42, 906... 

The proportional counters are an improvement over the Geiger-Miiller counters A carrier gas (90% Ar +10% CH4 quencher gas) is ionized by the high-energy (a or />) rays in the counter tube, but at a lower bias the generated (Ar+ + e ) ion pairs are coaxed by this bias to form a Townsend avalanche of further ion pairs, whose overall intensity is proportional to the energy of the incoming a or /J rays. 

X-Ray Patterns and Calculations. We used, under the same conditions, the apparatus previously employed in studying MgGa204 and CdGa204 (6), and our calculations were carried out in the same manner. Intensity measurements were made with a Geiger-Miiller counter. The wavelength used was that of CuKa. 

To overcome these limitations, the self-quenching proportional counter has been developed. This counter is very much like the Geiger-Miiller counter in construction. The electrons and positive ions from the primary ionizing event go to their respective electrodes, but the production of additional electrons through positive-ion bombardment of the... 

Geiger-Miiller counter (Geiger counter) an instrument that measures the rate of radioactive decay based on the ions and electrons produced as a radioactive particle passes through a gas-filled chamber. (21.4)... 

Many types of detectors, such as Geiger-Miiller counters, proportional counters and scintillation detectors, are used for charged particle detection. The selection is made on the basis of resolution and range of particle in the gas or scintillator. In some cases, the particles are not completely stopped within the detector for an energy measurement, but deposit only a portion of their energy. This is related to the relative ionization of the particle and can be used to identify different kinds of particles. 

Gas-filled detectors are used for X-rays or low energy gamma rays. These include ionization chambers, proportional counters and Geiger-Miiller counters. Scintillation detectors are used in conjunction with a photomultiplier tube to convert the scintillation light pulse into an electric pulse. Solid crystal scintillators such as Csl or Nal are commonly used, as well as plastics and various liquids. 

A common gas ionization counter is the Geiger-Miiller counter (Figure 26-5). Radiation enters the tube through a thin window. Windows of different stopping powers can be used to admit only radiation of certain penetrating powers. 

When the voltage is increased some more, a single photon is enough to trigger an avalanche process that becomes widespread. The intensity of the produced current is no longer proportional to the intensity of the X-ray beam. This is the Geiger-Miiller counter area . 

Surface self-diffusion is the two-dimensional analogue of the Brownian motion of molecules in a liquid bulk. Measurements of self-diffusion have to be performed in complete absence of any Marangoni flow caused by surface tension differences. Such experimental conditions are best established in an insoluble monolayer where one part consists of unlabelled and the other of radio-tracer labelled molecules. The movement of molecules within the surface monolayer can be now observed by using a Geiger-Miiller counter. There are possible effects of liquid convective flow in the sublayer which was discussed for example by Vollhardt et al. (1980a). With e special designed apparatus Vollhardt et al. (1980b) studied the self-difihision of different palmitic and stearic acid and stearyl alcohol and obtained self-diffusion coefficients between l-i-4 lO cm /s. 

Positron production Electron capture Decay series Nuclear transformation Transuranium elements Geiger-Miiller counter Scintillation counter Half-life... 

Radioactivity is detected by instruments such as the Geiger-Miiller counter. 

When using a Geiger-Miiller counter to measure radioactivity, one must maintain the same geometrical orientation between the sample and the Geiger-Miiller tube to compare different measurements. Why ... 

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