Radiation detection devices

There are not many uses for polonium. Probably the most important is as a source of alpha particles (nuclei of helium atoms) and high-energy neutrons for research and radiation studies. It is also used to calibrate radiation-detection devices. 

All methods of radiometric analysis involve, of course, the use. of various radiation detection devices, The devices available for measuring radioactivity will vary with the types of radiations emitted by the radioisotope and the kinds of radioactive material. Ionization chambers are used for gases Geiger-Miiller and proportional counters for solids liquid scintillation counters for liquids and solutions and solid crystal or semi-conductor detector scintillation counters for liquids and solids emitting high-energy radiations. Each device can be adopted to detect and measure radioactive material in another state, e.g., solids can be assayed in an ionization chamber. The radiations interact with the detector to produce a signal,... 

Radioactivation Analysis. The principle of this technique is that a stable isorope when irradiated by neurrons, by charged particles such as protons or deuterons or by gamma rays, can undergo a nuclear reaction to produce a radioactive nuclide. After the radionuclide is formed, and its radiations have been characterized by radiation detection devices, calculations can be made of the elements contained in the sample before irradiation. 

The curie, abbreviated Ci, is a standard unit of radioactive decay. It was originally defined as the rate at which 1 g of radium decays. Because of the relatively long half-life of Ra, the isotope served as a convenient standard. The curie is now defined as the quantity of any radioactive substance in which the decay rate is 3.700 X 10 disintegrations per second (2.22 X 10 DPM). Because the efficiency of most radiation detection devices is less than 100%, a given number of curies almost always yields a lower than theoretical count rate. Hence, there is the distinction between DPM and CPM. For example, a sample containing 1 /rCi of radioactive material has a decay rate of 2.22 x lO DPM. If only 30% of the disintegrations are detected, the observed count rate is 6.66 X 10 CPM. 

The changes that take place when radiation interacts with matter (such as photographic film) provide the basis of operation for various radiation detection devices. 

Some cancers can be caused by exposure to radiation. Being at the site where a dirty bomb exploded does not guarantee that people were exposed to the radioactive material. Until doctors are able to check people s skin with sensitive radiation detection devices, it will not be clear whether they were exposed. Just because people are near a radioactive source for a short time or get a small amount of radioactive material on them does not mean that they will get cancer. Doctors will be able to assess risks after the exposure level has been determined. 

Geiger-Miiller tube A radiation-detection device operating on the principle that ions form when radiation passes through a tube filled with low-pressure gas. 

After cleaning a radiation-contaminated wound, you should recheck it with a radiation detection device to be sure the radioactive material has been removed. 

When you are called to evaluate a suspicious powder, think of anthrax spores and radioactive material. W>u can use the anthrax test kit (see Practical Skills 4 ) and a radiation detection device ( Practical Skills 6 ) for field testing. 

The Abacus is a handheld,-digital radiation detection device that enables you to. complete your surveys automatically... 

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