Dosimeters are portable devices used to measure a person’s or an object's accumulated dose of ionizing radiation exposure. They are used for continuous monitoring over a certain period of time. This dose could originate from radiation being emitted by radioactive isotopes or from external radiation fields. They normally measure and store dose of gamma and x-ray radiation, sometimes beta and neutron radiation for the advanced dosimeters used in homeland security or power plants.
Dosimeter Shop is an online store that specializes in selling the best radiation detector and Geiger counter equipment on the market. The prices listed on our website is in US dollars. These devices are used to detect invisible, mostly harmful, radioactive particles namely Gamma, Beta, Alpha and X-rays.
Both Gamma and X-rays are part of the electromagnetic spectrum, specifically at its high frequency, short wavelength end. That same spectrum also includes the more familiar ultraviolet light, visible light, infrared rays, microwaves, and radio waves, listed in order of decreasing frequency and increasing wavelength from Gamma and X-rays.
As the four major types of ionizing radiation go, Gamma and X-rays are very powerful and potentially very dangerous. They can pass through virtually anything, and are effectively shielded or absorbed only by materials of high atomic weight such as lead. Because of their penetrating ability, X-rays are used to see inside the human body, destroy cancer cells in radiation therapy, or analyze the internal structure of rocks and minerals, for instance.
Gamma rays are produced naturally by the sun and other bodies in outer space, their transmission to earth being known as "cosmic radiation". Certain minerals that make up part of the earth containing the radioactive elements Uranium and/or Thorium also emit Gamma rays. This cosmic radiation, along with these radioactive earth minerals, combine to produce the "background count" of a Geiger counter. That is, even when a Geiger counter is removed from a specific radioactive object, the meter will still register a background level or count of radioactivity. This might typically be in the range of 20 counts per minute, but will vary depending upon where it is on the earth. The background count should always be factored in or "subtracted" from the overall reading derived from a specific radioactive source. X-rays, being very similar to Gamma rays, are produced from man-made sources such as X-ray tubes, arcs, and lamps.
While not part of the electromagnetic spectrum, Alpha and Beta particles are the two other types of ionizing radiation detectable by Geiger counters. Alpha radiation consists of positively charged particles emitted from the nucleus of an atom in the process of decay. These particles are also very dense which, with their strong positive charge, precludes them from penetrating more than an inch of air or a sheet of paper. Because of this, Alpha particles are not a serious health hazard, except when they are emitted from within the body as a result of ingestion, for instance, when their high energy poses an extreme hazard to sensitive living tissue. Radioactivity of this nature is difficult to detect using a standard Geiger counter, but since most Alpha-emitting substances also produce Gamma rays, this can allow for detection in some cases.
Beta radiation consists of negatively charged particles emitted from an atom in the process of decay. These particles are relatively light and can penetrate somewhat better than an Alpha particle, though still only through a few millimeters of aluminum.
Below is some example of household items that can emit radioactive particles:
Smoke Detectors - Contain an Alpha and Beta ray producing radioactive isotope of the element Americium that senses smoke. This is sealed, though, and may not give you any reading
Lantern Mantels - Some of the mantels in camping lanterns, especially those from earlier years, are made of the radioactive element Thorium. Be careful not to inhale the mantle ash!
Watches - Some old watches and clocks, even gyroscopes, have dials painted in radium to make them glow in the dark. Radium emits Alpha and Gamma rays. More recently, Tritium, a radioactive isotope of Hydrogen, has been used to paint the dials, but it is too weak to penetrate the watch lens.
Camera Lenses - It has been reported that certain old Leica camera lenses colored yellow owe their hue to the presence of the radioactive element, Thorium.
Jewelry - Certain gems are irradiated by the radioactive element Radium, X-rays, or other particles to produce a color change. This can make the gem itself radioactive which can last for years in some cases. Also, cloisonné, an enameled variety of jewelry, is glazed with Uranium oxide.
Rocks and Minerals - Minerals such as uraninite and its pitchblende variety, also carnotite and thorianite, contain the radioactive elements Uranium and/or Thorium.
Pottery - Some older pottery such as the Fiesta Ware brand often found in antique stores is glazed with Uranium oxide. When broken, the dust can emit Alpha particles of radiation.
Furniture - More recently, certain metal objects in the home are reported to be partly made of spent radioactive material.