Trace radioisotope
A trace radioisotope is a radioisotope that occurs naturally in trace amounts (i.e. extremely small). Generally speaking, trace radioisotopes have half-lives that are short in comparison with the age of the Earth, since primordial nuclides tend to occur in larger than trace amounts. Trace radioisotopes are therefore present only because they are continually produced on Earth by natural processes. Natural processes which produce trace radioisotopes include cosmic ray bombardment of stable nuclides, ordinary alpha and beta decay of the long-lived heavy nuclides, thorium-232, uranium-238, and uranium-235, spontaneous fission of uranium-238, and nuclear transmutation reactions induced by natural radioactivity, such as the production of plutonium-239[1] and uranium-236[2] from neutron capture[3] by natural uranium.
Elements
തിരുത്തുകThe elements that occur on Earth only in traces are listed below.
| Element name | Chemical Symbol |
|---|---|
| Technetium | Tc |
| Promethium | Pm |
| Polonium | Po |
| Astatine | At |
| Radon | Rn |
| Francium | Fr |
| Radium | Ra |
| Actinium | Ac |
| Protactinium | Pa |
| Neptunium | Np |
| Plutonium | Pu |
Isotopes of other elements (not exhaustive):
- Tritium
- Beryllium-7
- Beryllium-10
- Carbon-14
- Fluorine-18
- Sodium-22
- Sodium-24
- Magnesium-28
- Silicon-31
- Silicon-32
- Phosphorus-32
- Sulfur-35
- Sulfur-38
- Chlorine-34m
- Chlorine-36
- Chlorine-38
- Chlorine-39
- Argon-39
- Argon-42
- Calcium-41
- Iron-52
- Cobalt-55
- Nickel-59
- Copper-60
- Germanium-64
- Selenium-79
- Krypton-81
- Strontium-90
- Rhodium-105
References
തിരുത്തുക- ↑ Curtis, David; Fabryka-Martin, June; Paul, Dixon; Cramer, Jan (1999). "Nature's uncommon elements: plutonium and technetium". Geochimica et Cosmochimica Acta. 63 (2): 275–285. Bibcode:1999GeCoA..63..275C. doi:10.1016/S0016-7037(98)00282-8.
- ↑ "Technical sheet about (nuclear) mass spectrometry" (PDF). Archived from the original (PDF) on 22 ജൂലൈ 2011. Retrieved 28 ഓഗസ്റ്റ് 2009.
- ↑ Wilcken, K.~M.; Barrows, T. T.; Fifield, L. K.; Tims, S. G.; Steier, P. (ജൂൺ 2007). "AMS of natural 236 U and 239Pu produced in uranium ores". Nuclear Instruments and Methods in Physics Research B. 259 (1): 727–732. Bibcode:2007NIMPB.259..727W. doi:10.1016/j.nimb.2007.01.210. hdl:1885/29151. S2CID 96531059.