Geiger counter, use

All three types of radiation are termed ionizing radiation as they strip off electrons from atoms they collide with to leave a charged ion behind. Sometimes this property can be used to detect the presence of these rays. Geiger counters use this property. This radiation also fogs a photographic film. This is shown up when it is developed. 

A handheld Geiger counter, used to detect radiation, is shown. Together with an isotope of radon, leaks can be located. IMAGE COPYRIGHT 2009, JOE WHITE. USED UNDER LICENSE FROM SHUTTERSTOCK.COM. 

The design of a Geiger counter used for the measurement of radioactivity. 

Berlin, and winner of the 1936 Nobel Prize in Chemistry and Hans Geiger, the codeveloper, with Walther Muller, of the Geiger counter used to measure radioactivity. This club was largely ineffective. 

Geiger counter A device used to detect and measure amounts of radioactivity. 

The methods for detection and quantitation of radiolabeled tracers are deterrnined by the type of emission, ie, y-, or x-rays, the tracer affords the energy of the emission and the efficiency of the system by which it is measured. Detection of radioactivity can be achieved in all cases using the Geiger counter. However, in the case of the radionucHdes that emit low energy betas such as H, large amounts of isotopes are required for detection and accurate quantitation of a signal. This is in most cases undesirable and impractical. Thus, more sensitive and reproducible methods of detection and quantitation have been developed. 

At present, the Geiger counter is the most popular x-ray detector in analytical chemistry. Although it is yielding ground to the proportional counter and the scintillation counter, it will be remembered for having greatly accelerated the use of x-ray emission spectrography in analytical chemistry. 

The enormous value of A means that Geiger counters respond satisfactorily to x-rays of long wavelengths. The counters are easy to use. They are now relatively stable and trouble-free—surprisingly so in view of the complexities described below. Frequent recalibration is desirable, however, in highly precise work. 

The cause of this difficulty therefore resides within the counter itself. The difficulty is described by saying that the Geiger counter has a dead time, by which is meant the time interval after a pulse during which the counter cannot respond to a later pulse. This interval, which is usually well below 0.5 millisecond, limits the useful maximum counting rate of the detector. The cause of the dead time is the slowness with which the positive-ion space charge (2.5) leaves the central wire under the influence of the electric field. This reduction in observed counting rate is known as the coincidence loss. 

When Fe-55 became available, Hughes and Wilezewski4 found it possible to improve further the valuable method just described by using this radioactive isotope as an x-ray source. Four millicuries of iron, in the form of a button that initially had 15(107) disintegrations per second, was mounted as shown in Figure 5-2, the Geiger counter being movable... 

In 1950, Beeghly6 published results obtained by Method I on tin plate. Pie used a polychromatic beam from a copper-target tube to excite the K lines of iron in the substrate and measured the intensity of the radiant energy that passed the collimating slit to reach the Geiger counter that served as detector (Figure 6-1). A manganese filter in the... 

The reader will appreciate that Figure 9-1 does not illustrate the alternative method of collecting information (2.6, 2.7) in which the output of a Geiger counter is used to charge a capacitor. This method has been put to good use by the Applied Research Laboratories (9.8). 

A Geiger counter monitors radiation by detecting the ionization of a low-pressure gas, as shown in the illustration. The radiation ionizes atoms of the gas inside a cylinder and allows a brief flow of current between the electrodes. The resulting electrical signal can be recorded directly or converted into an audible click. The frequency of the clicks indicates the intensity of the radiation. A limitation of Geiger counters is that they do not respond well to 7 rays. Only about 1% of the 7-ray photons are detected, whereas all the (3 particles incident on the counter are detected. Because the efficiency of a Geiger counter depends on the size of the tube, a counter used to monitor a wide range of activities usually contains two tubes of different sizes. 

A sample of iodine-128 was produced in a Szilard-Chalmers reaction by irradiating a sample of ethyl iodide in a neutron source. The radio-iodine was extracted with sodium thiosulfate solution and then counted in a Geiger counter at various time Intervals. Use the tabulated data of t in minutes against C counts/min to find the rate equation and the half time. 

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. 

Light is strong enough to knock off electrons from cesium, which makes this phenomenon useful as a coating for photoelectric cells and electric eye devices. Cesium iodide (Csl) is used in scintillation counters (Geiger counters) to measure levels of external radiation. It is also useful as a getter to remove air molecules remaining in vacuum tubes. 

Geiger counter. Also known as a scintillation counter. A device used to detect, measure, and record radiation. The instrument gets its name from one of its parts, the Geiger tube, which is a gas-fiUed tube containing coaxial cylindrical electrodes. 

---