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Specific activity (symbol a) is the activity per unit mass of a radionuclide and is a physical property of that radionuclide. [ 1 ] [ 2 ] It is usually given in units of becquerel per kilogram (Bq/kg), but another commonly used unit of specific activity is the curie per gram (Ci/g).
The decay-chain of uranium-238, which contains radium-226 as an intermediate decay product. 226 Ra occurs in the decay chain of uranium-238 (238 U), which is the most common naturally occurring isotope of uranium. It undergoes alpha decay to radon-222, which is also radioactive; the decay chain ultimately terminates at lead-206.
Because of its relative longevity, 226 Ra is the most common isotope of the element, making up about one part per trillion of the Earth's crust; essentially all natural radium is 226 Ra. [29] Thus, radium is found in tiny quantities in the uranium ore uraninite and various other uranium minerals, and in even tinier quantities in thorium minerals.
Radium (88 Ra) has no stable or nearly stable isotopes, and thus a standard atomic weight cannot be given. The longest lived, and most common, isotope of radium is 226 Ra with a half-life of 1600 years. 226 Ra occurs in the decay chain of 238 U (often referred to as the radium series). Radium has 34 known isotopes from 201 Ra to 234 Ra.
This work is in the public domain in the Philippines and possibly other jurisdictions because it is a work created by an officer or employee of the Government of the Philippines or any of its subdivisions and instrumentalities, including government-owned and/or controlled corporations, as part of their regularly prescribed official duties ...
Hence, ground water has a higher concentration of 222 Rn than surface water, because radon is continuously produced by radioactive decay of 226 Ra present in rocks. Likewise, the saturated zone of a soil frequently has a higher radon content than the unsaturated zone because of diffusional losses to the atmosphere.
The Department of Defense Activity Address Code (DoDAAC) is a six position code that uniquely identifies a Department of Defense unit, activity, or organization that has the authority to requisition, contract for, receive, have custody of, issue, or ship DoD assets, or fund/pay bills for materials and/or services. The first positions of the ...
Radon-222 (222 Rn, Rn-222, historically radium emanation or radon) is the most stable isotope of radon, with a half-life of approximately 3.8 days. It is transient in the decay chain of primordial uranium-238 and is the immediate decay product of radium-226.