Cosmogenic radionuclides in ice cores

Cosmogenic radionuclides are produced continuously by cosmic rays penetrating from the space into the atmosphere. When cosmic ray particles impinge on the atmosphere they induce nuclear reactions producing secondary particles and a variety of new nuclides most of which are radioactive. Depending on the energy of theprimary particle a cascade develops through the atmosphere until all the secondary particles are used up in nuclear reactions or stopped by collisions and ionization processes. Since the main target elements of the atmosphere are nitrogen, oxygen, and argon most of the radionuclides produced have masses smaller than 40. In Table 1 some basic properties of the main cosmogenic radionuclides produced in the atmosphere are listed. The production rates are given as estimated mean global values. Some of the radionuclides, marked with an asterisk, are also produced artificially in considerable amounts by nuclear bomb tests, nuclear reactors, and accelerator facilities. (orig.)