Authors: Nguyen Anh Tuan, Chau Van Tao, Chary Rangacharyulu
Abstract:
A permanent electric dipole moment (EDM) of a particle or system is a separation of charge along its angular momentum axis and is a direct signal of T violation and, assuming CPT symmetry, CP violation. For over 60 years EDMs have been studied, first as a signal of a parity-symmetry violation and then as a signal of CP violation that would clarify its role in nature and in theory. Contemporary motivations include the role that CP violation plays in explaining the cosmological matter-antimatter asymmetry and the search for new physics. Experiments on a variety of systems have become ever-more sensitive, but provide only upper limits on EDMs, and theory at several scales is crucial to interpret these limits. Nuclear theory provides connections from standard-model and beyond-standard-model physics to the observable EDMs, and atomic and molecular theory reveal how CP violation is manifest in these systems. EDM results in hadronic systems require that the standard-model QCD parameter of ¯θ must be exceptionally small, which could be explained by the existence of axions, also a candidate dark-matter particle. Theoretical results on electroweak baryogenesis show that new physics is needed to explain the dominance of matter in the Universe. Experimental and theoretical efforts continue to expand with new ideas and new questions, and this review provides a broad overview of theoretical motivations and interpretations as well as details about experimental techniques, experiments, and prospects. The intent is to provide specifics and context as this exciting field moves forward.
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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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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 2s22p 2P1/2→2s23s 2S1/2 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 ⟨r2c⟩11−⟨r2c⟩10=−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 Deep Underground Neutrino Experiment (DUNE) is an international research collaboration aimed at exploring topics related to neutrinos and proton decay, which should start collecting data around 2025. In a recent study featured in Physical Review Letters, a team of researchers at Ohio State University have showed that DUNE has the potential to deliver groundbreaking results and insight about solar neutrinos.
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Researchers at the Center for Quantum Nanoscience (QNS) within the Institute for Basic Science (IBS) at Ewha Womans University have made a major scientific breakthrough by performing the world's smallest magnetic resonance imaging (MRI). In an international collaboration with colleagues from the U.S., QNS scientists used their new technique to visualize the magnetic field of single atoms.
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Semiconductors are the basic building blocks of digital devices. Improvements in semiconductor functionality and performance are likewise enabling next-generation applications of semiconductors for computing, sensing and energy conversion. Yet researchers have long struggled with limitations in their ability to fully understand the electronic charges inside semiconductor devices and advanced semiconductor materials, limiting researchers' ability to drive further advances.
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