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BỘ MÔN VẬT LÝ HẠT NHÂN - KỸ THUẬT HẠT NHÂN

Abstract :

The first laser spectroscopic determination of the change in the nuclear charge radius for a five-electron system is reported. This is achieved by combining high-accuracy ab initio mass-shift calculations and a high-accuracy measurement of the isotope shift in the 2s22p2P1/22s23s2S1/2 ground state transition in boron atoms. Accuracy is increased by orders of magnitude for the stable isotopes 10,11B and the results are used to extract their difference in the mean-square charge radius r2c11r2c10=0.49(12)fm2. The result is qualitatively explained by a possible cluster structure of the boron nuclei and quantitatively used to benchmark new ab initio nuclear structure calculations using the no-core shell model and Green’s function Monte Carlo approaches. These results are the foundation for a laser spectroscopic determination of the charge radius of the proton-halo candidate 8B.

 

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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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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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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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