Cosmic rays variations

Belov A., L. Dorman, E. Eroshenko et al. The relation between malfunctions of satellites at different orbits and cosmic ray variations , Proc. 28-th Intern. Cosmic Ray Conf., Tsukuba, 7, 4213-4216 (2003)... 

Bonino G, Cini Castagnoli G, Bhandari N, Della Monica P, Taricco C (1999) Galactic cosmic ray variations in the last two centuries recorded by cosmogenic " " Ti in meteorites. Adv Space Res 23 607-610... 

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 instrument MIMOS 11 is extremely miniaturized compared to standard laboratory Mossbauer spectrometers and is optimized for low power consumption and high detection efficiency (see Sect. 3.3) and [326, 327, 336-339]. All components were selected to withstand high acceleration forces and shocks, temperature variations over the Martian diurnal cycle, and cosmic ray irradiation. Mossbauer measurements can be done during day and night covering the whole diurnal temperature... 

The generation process for radiocarbon in the atmosphere makes C02 which enters the biosphere because of the long lifetime the mixing is essentially perfect. We assumed the rate of production to be constant which turns out to be somewhat incorrect. Variations of about 10 percent can be seen back in time to early Egyptian periods and before. The earth s magnetic field was apparently weaker then as the cosmic rays delivered to the surface and the atmosphere were more intense. 

One of the most interesting of the geophysics results from radiocarbon dates is the history of the sun. Apparently, it is registered in fluctuations of the cosmic ray intensity. These are fluctuations of rather short duration in terms of the radiocarbon lifetime, perhaps a century or so, and apparently they are caused by variations in the solar wind due to long-term changes in the solar emissions. This idea has been developed in some detail recently by Dr. Lai and his collaborators. It promises to give us a way of watching the history of the sun over tens of thousands of years. This fine structure on the curve of calibration was discovered by Dr. Suess and others. 

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 advent of new techniques to collect undisturbed sediment cores, with well preserved sediment - water interface has brought into sharper focus the various deep sea sedimentary processes, their rates and their effects on the preserved records. As mentioned earlier, recent studies have shown that the record contained in sediments is not a direct reflection of the delivery pattern of a substance to the ocean floor as has so far been assumed the record is modified as a result of several complex physical, chemical and biological processes. Therefore, information on the temporal variations in the tracer input to oceans, if sought, has to be deciphered from the sediment-residuum. In the following we consider one specific example of retrieval of information from the sediment pile the application of deep sea sediments to obtain historical records of cosmic ray intensity variations. 

The amplitude attenuation factor, 1 + (tu/Ai)2 for nuclides satisfying relation [14], for various values of Ax and T are presented in figure 9. It is obvious from figure 9 that the attenuation is minimal when Ai > u>, i.e., when the removal residence time of the nuclide from sea water is less than the period in the variation of cosmic ray intensity. 

Figure 9. Calculated attenuation factors for various values of T (period in the sinusoidal cosmic ray intensity variations) and A (the total rate constant). See section on deep-sea sediments and historical records for discussion.

In the preceding discussion, we have calculated the attenuation factors for 10Be for three periods, 200, 7 x 103 and 10s years. Of these the 200 and 7000 year periods are well established and have been ascribed to solar cycle variations and earth s magnetic field excursions, respectively. For detailed calculations on the effect of these variations on the production rates of isotopes by cosmic rays reference is made to Castagnoli and Lal, 75.)... 

With these circulation features in mind, the apparent stratospheric residence times deduced from the tungsten tracer data (9), the cosmic ray spallation product distribution (2), and the 90Sr concentration variations displayed by recent balloon samples (23) can be placed in better perspective. 

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

Secondary cosmic ray flux and cosmic ray composition at the Earth s surface are complex quantities to evaluate, and in practice assumptions about the constancy of cosmic rays over timescales relevant to paleoaltimetry research. Short time scale variations in production rates, such as might result from the 11-year cyclicity in the cosmic ray flux due to solar flares (Raisbeck et al. 1990), will average out of the data over million-year timescales. Likewise, assumptions about the constancy of atmospheric density must be made so that atmospheric depth can be converted to elevation. 

Figure 2.12 Correlated isotopic variations observed in stepwise heating of lunar breccia 60019. The linear array suggests that only two components, in varying proportions, are present one is trapped solar wind, presumably near BEOC-12, the other is in situ cosmic ray-induced spallation, relatively rich in 124Xe and 126Xe.

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