Well counter gamma rays

A Geiger counter is a useful tool for measuring radioactivity in almost anything. It can detect alpha and beta particles, as well as gamma rays. 

Spectral Gamma Ray Log. This log makes use of a very efficient tool that records the individual response to the different radioactive minerals. These minerals include potassium-40 and the elements in the uranium family as well as those in the thorium family. The GR spectrum emitted by each element is made up of easily identifiable lines. As the result of the Compton effect, the counter records a continuous spectrum. The presence of potassium, uranium and thorium can be quantitatively evaluated only with the help of a computer that calculates in real time the amounts present. The counter consists of a crystal optically coupled to a photomultiplier. The radiation level is measured in several energy windows. 

Gamma-ray cylindrical sources The point source is mounted at the end of a plastic rod (diameter 9 mm). A disc can be fitted to this rod to facilitate its use in automatic samples changer. These sources are particularly suited for the calibration of well-type Nal(Tl) scintillation counters. 

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. 

Fig. 3 A typical well counter used for measurement of gamma rays.

Na and 131I are both (3 and y emitters, and are often used in biochemical research. Gamma rays are more energetic than P particles, and denser materials are necessary for absorption. A gamma counter (Figure 6.8) consists of a sample well, a sodium iodide crystal as fluor and a photomultiplier tube. 

Figure 32-5 is a schematic of a well-type scintillation counter that is used for gamma-ray counting. I fere, the sample is contained in a small vial and placed in a cylindrical hole, or well, in the. scintillating crystal of the counter. 

Radioactivity is measured by detecting the products of radioactive decay processes. The most well-known instrument used for this purpose is the Geiger counter. A Geiger counter is sensitive to the products of nuclear decay, including alpha and beta particles and gamma rays. The units used to quantify radiation are the Curie or the Bec-querel, which describe the number of nuclear decays a substance undergoes per unit of time. 

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