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 edit

The elements that occur on Earth only in traces are listed below.

Element name Chemical
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):

References edit

  1. ^ 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.
  2. ^ "Technical sheet about (nuclear) mass spectrometry" (PDF). Archived from the original (PDF) on 22 July 2011. Retrieved 28 August 2009.
  3. ^ Wilcken, K.~M.; Barrows, T. T.; Fifield, L. K.; Tims, S. G.; Steier, P. (June 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.