Atmospheric Gamma Rays

Gamma rays are produced in copious quantities in the upper atmosphere of the Earth as a consequence of cosmic-ray interactions. Balloon experiments rely typically on the growth curve technique to estimate the contribution of atmospheric gamma rays to the observed event count rate. In this method, the total count rate of the detector is determined as a function of the residual atmosphere remaining 

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Radiolytic ethylene destruction occurs with a yield of ca. 20 molecules consumed/100 e.v. (36, 48). Products containing up to six carbons account for ca. 60% of that amount, and can be ascribed to free radical reactions, molecular detachments, and low order ion-molecule reactions (32). This leaves only eight molecules/100 e.v. which may have formed ethylene polymer, corresponding to a chain length of only 2.1 molecules/ ion. Even if we assumed that ethylene destruction were entirely the result of ionic polymerization, only about five ethylene molecules would be involved per ion pair. The absence of ionic polymerization can also be demonstrated by the results of the gamma ray initiated polymerization of ethylene, whose kinetics can be completely explained on the basis of conventional free radical reactions and known rate constants for these processes (32). An increase above the expected rates occurs only at pressures in excess of ca. 20 atmospheres (10). The virtual absence of ionic polymerization can be regarded as one of the most surprising aspects of the radiation chemistry of ethylene. 

Interrogating the light from stars and the absorption features of atoms and molecules in-between requires some fairly complicated optics in the form of a telescope. However, the telescopes are not restricted to the parts of the electromagnetic spectrum that you can see but use radiation from microwaves to gamma rays to observe the Universe. There is too much to learn about the optics or even adaptive optics of telescopes to be discussed here but there are some properties of telescopes that we must know because they are important for the identification of atoms and molecules. We shall discuss three telescope considerations the atmosphere, the spatial resolution and the spectral resolution. 

UV, X-ray and gamma-ray observatories are all space-borne because these wavelengths are blocked by the Earth s atmosphere. And what could be more natural than to place eyes in orbits But who sent them up there and why Astrophysicists are no longer naive when it comes to the relationship between the tools of military surveillance and those of astronomy. And this is not a recent invention. Galileo himself offered his refracting telescope to the delighted dignitaries of the Venetian senate in order to draw attention to its military potential. His salary was immediately doubled and he was appointed professor at the University of Padua ... 

There is indication from the work of one of the authors (H18) that chain utilization of oxygen occurs in the oxidation of ethylene when aqueous solutions of ethylene and oxygen under several atmospheres pressure are irradiated with gamma rays from Co60. 

A last possibility to produce relativistic electrons in the cluster atmospheres is due to the interaction of high-E gamma-rays with low energy (CMB/IR) photons, with the subsequent production of e pairs (Timokhin et al. 2003). The main uncertainty of this last model is the unknown origin of the very high-E gamma-rays in clusters. 

The relative penetrating powers of the three kinds of radiation are approximately in the range of 1,100, and 10,000 for the alpha, beta, and gamma rays, respectively. The penetrating power of alpha rays is less than 0.2 m (8 in.) of atmospheric air. Beta radiation can penetrate approximately 6 mm (0.25 in.) of aluminum. Gamma rays are used for level measurement because of their high penetrating power, and because they cannot be deflected. 

The sample used for the experiments is Aciplex-SF-1004 (10x10x0.117 mm3). The sample was irradiated at room temperature and atmospheric pressure with 1.17 and 1.33 MeV gamma-ray from a cobalt-60 source in the Takasaki Research Establishment of Japan Atomic Energy Research Institute (JAERI). The absorption doses of the sample by gamma-ray were from 1 to 173 kGy. 

Fig. 1 shows proton conductivity for the perfluorosulfonic acid membranes, measured at 300 K in air by the DC resistance measurement, after gamma-ray irradiation at the several doses up to 414 kGy. The conductivity was calculated from the applied voltage and the measured current and dimension of the polymers. It can be seen in Fig.l that the conductivity increases with increasing the dose. The conductivities at 300 K in air atmosphere rapidly increased until about 50 kGy, and achieved to be higher by about three orders of magnitude than that of the unirradiated one. 

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