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The depth-dose curve depends on the inhomogeneity of the material irradiated by electron beam

Abstract:

Electron linear accelerator with average energy 9.92 ± 0.48 MeV, UELR-10-15S2, was set up and operated at the Research and Development Center for Radiation Technology, Vietnam Atomic Energy Institute, for irradiating foods and medical devices directly without X-ray converter. Inside the homogenous products, the depth-dose curve depends on electron beam energy and product density, and moreover, it also depends on the inhomogeneity of the irradiated material. In this article, the depth-dose distribution is calculated by MCNP simulation code and measured by a film dosimeter inside the inhomogeneous products. The results show that the maximum deviation of the depth-dose curve between inhomogeneous and homogeneous products with the same density is about 20%. So the area density limit for irradiating double sided on the electron beam (9.92 ± 0.48 MeV) is in the range from 6.1 to 9.7 g/cm2 instead of 8.5 g/cm2 in general.

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Recent advances in the observation of high-energy radiations, including X-rays and gamma-rays, have unveiled many high-energy aspects of the universe. To achieve a complete understanding of these radiations, however, researchers need to find out more about the high-energy particles (i.e. cosmic rays) that produce them. In fact, non-thermal radiations characterized by the power-law spectrum are all backed by the acceleration and propagation of these rays.

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The electronic Barnett effect, first observed by Samuel Barnett in 1915, is the magnetization of an uncharged body as it is spun on its long axis. This is caused by a coupling between the angular momentum of the electronic spins and the rotation of the rod.

Using a different method from that employed by Barnett, two researchers at NYU observed an alternative version of this effect called the nuclear Barnett effect, which results from the magnetization of protons rather than electrons. Their study, published in Physical Review Letters (PRL), led to the first experimental observation of this effect.

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Researchers at Tokyo Institute of Technology have found a simple, yet highly versatile way to generate "chaotic signals" with various features. The technique consists of interconnecting three ring oscillators, effectively making them compete against each other, while controlling their respective strengths and their linkages. The resulting device is rather small and efficient, thus suitable for emerging applications such as realizing wireless networks of sensors.

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University of Chicago scientists are part of an international research team that has discovered superconductivity—the ability to conduct electricity perfectly—at the highest temperatures ever recorded.

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Revised definitions for four scientific units — the kilogram, the kelvin, the ampere and the mole — come into force today. The change, decided last year, means that all the base units of the International System of Units (SI) are now defined according to fixed fundamental constants of nature, rather than by a physical object or arbitrary reference.

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