Cosmic ray-produced

Suess, H. E. (1965). Secular variations of the cosmic-ray-produced carbon-14 in the atmosphere and their interpretation, /. Geophys. Res. 70,5937-5952. 

The two isotopes of carbon that occur naturally are 12C (98.89%) and 13C (1.11%). Cosmic rays produce neutrons that interact with 14N in the upper atmosphere to produce 14C and protons,... 

Radioactive and chemical dating methods are yielding most valuable information on the history of the earth and the planetary system. In this paper mainly methods using cosmic ray produced isotopes are discussed. 

The Use of Cosmic Ray Produced Isotopes for Studies of the Environmental System and Its History... 

Table 1. Cosmic Ray Produced Noble Gas Radioisotopes Tl/2 > 1 month.

Kr 10.6 y f Cosmi c ray produced Anthropogenic 3 x 104 dpm/L Kr Cosmic ray produced component not yet identified Fission product... 

One is compelled to pose the question if experimentally it will become possible to decide whether the 14C variations observed on tree-ring samples, peat bogs, sediments, etc., are primarily caused by an external forcing of the system (production rate variations) or by an internal one. Recent progress in detection of small numbers of nuclei of an isotope by mass spectrometry based on the use of a particle accelerator [57,58] make it possible to measure the cosmic ray produced 10Be or 36C1 deposited in only 1 kg of ice. These isotopes get attached to aerosol particles and deposited with them. 

The discovery of cosmic ray produced 81Kr in meteorites [l]1 introduced a new method of high sensitivity measurements of 81Kr concentrations and cosmic ray exposure dating. The method consists of a direct measurement of both radioactive 81Kr atoms (Ty2 = 2.13 x 105y, [2] and of stable spallation Kr atoms by a... 

Kr isotopic data derived from either stepwise or total sample analysis represent generally mixtures of several components, but equations (4) and (5) require the identification of the cosmic ray produced spallation component. As long as spallation Kr is the major component, the analysis of isotopic spectra is reasonably... 

Figure 1. A retraced portion of the (fading) 14-year-old Kr mass spectrum (79.0 to 82.0 amu) in the Macibini meteorite that established the presence of cosmic ray-produced slKr ( 80.917 amu).

Marti, Kurt, "Mass-spectrometric detection of cosmic-ray-produced 81Kr in meteorites and the possibility of Kr-Kr dating", Phys. Rev. Lett., 1967, US, (7), 264-266. 

Regnier, S., Hohenberg, C. M., Marti, K., and Reedy, R. C., "Predicted versus observed cosmic-ray-produced noble gases in lunar samples Improved Kr production ratios", Proc. Lunar Planet. Sci. Conf., 10th, 1979, 1565-1586. 

Lai, D., Peters, B., Cosmic-ray produced isotopes and their applications to problems in geophysics, In Progress in Elementary Particle and Cosmic Ray Physics, North Holland Publishing Co., Amsterdam, Vol. 6, p. 1-74, 1962. 

Lai, D.7 Peters, B., Cosmic ray produced radioactivity of the earth, In Handbuch der physik, Springer-Verlag, Berlin, 46, 551-612 (1967). 

Numerous radionuclides have been applied to marine sedimentary problems. These are generally grouped into cosmic-ray produced (cos-mogenic) nuclides ( C, °Be, Be, "Al), nuclear bomb-produced (fallout) nuclides ( Cs, plutonium isotopes, 24iAm), and naturally occurring nuclides ultimately derived from the decay of 38u, and 232xh parents. 

When a meteorite falls onto the Earth s surface, it becomes for the most part shielded from the effects of cosmic rays. The cosmic-ray-produced nuclides cease to form so the exposure clock stops. However, because many of the cosmic-ray produced nuclides are radioactive, several new clocks start that can be used to estimate the time that a meteorite has been on the Earth s surface. 

Tihe atmosphere contains many radionuclides which result from nuclear weapons testing and from natural processes. The nuclear weapons-produced radionuclides include both fission products and activation products from the construction materials of the device. The natural radionuclides include the decay products of radon and thoron, the natural radionuclides in the airborne dust, and the cosmic-ray-produced radionuclides which result from spallation reactions in the atmosphere. Through the determination of the absolute and relative concentrations of this wide spectrum of radionuclides, it should be possible to define the rates of both the long term stratospheric processes and the shorter term tropospheric processes. At the beginning of 1962 a ground-level... 

The seasonal variations in the ground-level air concentrations of nuclear weapons-produced and cosmic-ray-produced radionuclides are... 

Short Lived Cosmic Ray-Produced Radionuclides as Tracers of Atmospheric Processes... 

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