Cosmogenic radionuclides

In the marine environment, the numerous radionuclides can be classified into three broad categories based on their production or origin (1) those derived from the weathering of continental rocks, the primordial radionuclides, (2) those formed from cosmic radiation, the cosmogenic radionuclides, and (3) those artificially introduced into nature, the anthropogenic or transient radionuclides and tracers. The primordial radionuclides (e.g. Th, and U) were... 

Cosmogenic radionuclides are formed in the upper atmosphere by the interaction of cosmic rays, primarily from the sun, with elements present in the atmosphere (e.g. 0, and " Ar). Their half-lives range from months to... 

Cosmogenic radionuclides are produced in the upper atmosphere by spallation reactions of cosmic rays with atmospheric elements. The most common... 

Pb-210 and the Cosmogenic Radionuclides. We noted earlier that our measurements of Pb-214 were really measurements of Po-214 decay, that is, the production of Pb-210. The mean AMAD of these measurements was about 0.16 um, with the AMAD of Pb-210 predicted to be 0.18 um after recoil. However, the summer AMAD of Pb-210, after aging in the atmosphere for about a week (Moore et al., 1980), was closer to 0.4 um, indicating that Pb-210 s AMAD approximately doubles during its lifetime in the atmosphere. The limited measurements reported here suggest that the AMAD of Pb-210 is smaller in winter than summer, possibly reflecting differences in aerosol growth rates. The summer measurements were also not different from simultaneous SoJ measurements. 

The cosmogenic radionuclides, particularly Be-7, are associated with slightly smaller aerosols than sulfate, both in winter and summer. The reasons for this difference may be either (1) faster growth rates of secondary aerosols in plumes... 

Cosmogenic Radionuclides in the 105-107 Year Region Results and Prospects for High-Energy Ion Counting...J. R. Arnold. 

Frank M., Schwaz B., Baumann S., Kubik P.W., Suter M., and Mangini A. (1997) A 200 kyr record of cosmogenic radionuclide production rate and geomagnetic field intensity from lOBe in globally stacked deep-sea sediments. Earth Planet Sci. Lett. 149, 121-129. 

The most famous cosmogenic radionuclide is 14C (t1/2 = 5730 a), which is produced by the interaction of cosmic ray neutrons via an (n,p) reaction with nitrogen [14N(n, p)14C], whereas the radioactive decay of 14C takes place by (3 decay to form the stable 14N isotope. 14C is the most important cosmogenic radionuclide for dating (see Section 9.7.5) in archaeology and can be analyzed using isotope sensitive accelerator mass spectrometry. Extremely small isotope ratios 14C/12C = 12 in nature can be measured by means of AMS.28... 

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