Abstract
A 6-GeV lattice with the horizontal tune near a 3rd-order resonance line at 3
ν
x
=2 is designed for studying the transverse resonance island buckets (TRIBs) at the Cornell Electron Storage ...Ring (CESR). The distribution of 76 sextupoles powered individually is optimized to maximize the dynamic aperture and achieve the desired amplitude-dependent tune shift
α
xx
and the resonant driving term
h
30000
, which are necessary conditions to form stable island buckets. The particle tracking simulations are developed to check and confirm the formation of TRIBs at different tunes with clearing kicks in this TRIBs lattice. Finally, the lattice is loaded in CESR and the TRIBs are successfully observed when the horizontal fractional tune is adjusted to 0.665, close to the 3rd-order resonance line. Bunch-by-bunch feedback is also explored to clear the particles in the main bucket and the island buckets, respectively.
Diamond microcrystals have been synthesized using ultrasonic cavitation of a suspension of hexagonal graphite in various organic liquid media, at an average bulk temperature of the liquid up to 120°C ...and at atmospheric pressure. The yield of diamond is up to 10% by mass. The diamonds were characterized by scanning electron microscopy, X-ray diffraction and laser Raman spectroscopy. Analysis of the crystallite size distribution showed that the diamonds were nearly mono-dispersed, having a size 6 or 9μm ± 0.5μm, with cubic, crystalline morphology.
In this work, we consider the problem of eigenfrequencies of elastic shear waves propagating in a layer whose Young's modulus and density are functions of the longitudinal coordinate. Taking into ...account the material inhomogeneity makes the problem of the eigenfrequencies of the waves propagating in the layer more complicated. In this paper, the problem of pure shear is considered. To solve the problem, we use an integral formula which allows us to represent the general solution of the original equation with variable coefficients in terms of the general solution of the accompanying equation with constant coefficients.
Abstract
Investigating the reflection and refraction of electroelastic waves at a plane interface without acoustic contact between two piezoelectric half-spaces of different textures, it was found ...that: (i)As a result of the incidence of a two-component electroelastic shear wave on the interface between the media, the same wave is reflected into the first half-space, and a three-component electroelastic plane strain wave is refracted into the second half-space. In the utmost cases, in layered inhomogeneous waveguide, a wave hybrid of electroacoustic waves is formed. This makes it possible to transmit along the boundary of non-acoustic contact of media a hybrid of electroacoustic surface waves of the Gulyaev-Bluestein type and Rayleigh type localized near this boundary. (ii)As a result of the incidence of a two-component electroelastic plane strain wave on the interface between the media, the same wave is reflected into the first half-space, and a three-component electroelastic shear wave is refracted into the second half-space. This also makes it possible to organize a hybrid of electroacoustic waves of elastic shear and plane deformation of the type of periodic electroelastic Floquet waves in a periodically transversely inhomogeneous piezoelectric composite. The conditions for the possible formation of the hybrid and the characteristics of their propagation in the layered composites of piezoelectrics of the hexagonal symmetry class 6
mm
and
6
¯
m
2 are discussed.
Studies show that correlations of ESG ratings provided by various rating agencies are fairly weak. The challenge related to disparities in ESG ratings often referred to as “divergence” of ESG ratings ...is widely discussed in academic and professional community. This divergence may lead to investment decisions made based on misleading information and thus, distort the re-orientation of capital flows into sustainable business. For this reason, there is a growing legislative and regulatory focus on ESG related issues, including the activities of ESG rating providers. The purpose of this article is to conduct a preliminary assessment of the approaches of foreign regulators in addressing the issue of divergence of ESG ratings through an in-depth exploration of this phenomenon and its sources. A careful study of the underlying factors of ESG rating disparities allows us to consider the identified foreign regulatory trends in the context of their focus on eliminating these factors. The methodology of the article is based on the review of the available academic literature and empirical research, study of ESG rating methodologies and analysis of adopted or proposed foreign regulatory requirements. A number of regulatory trends has been identified, which together shape the premise for the development of the regulatory framework of ESG ratings in the future. These trends include a strong focus on corporate ESG reporting and increasing transparency of ESG rating methodologies. However, elimination of the main sources of divergence are not among the tasks of the foreign regulators.
Positron beams, both polarized and unpolarized, are identified as important ingredients for the experimental programs at the next generation of lepton accelerators. In the context of the hadronic ...physics program at Jefferson Lab (JLab), positron beams are complementary, even essential, tools for a precise understanding of the electromagnetic structure of nucleons and nuclei, in both the elastic and deep-inelastic regimes. For instance, elastic scattering of polarized and unpolarized electrons and positrons from the nucleon enables a model independent determination of its electromagnetic form factors. Also, the deeply-virtual scattering of polarized and unpolarized electrons and positrons allows unambiguous separation of the different contributions to the cross section of the lepto-production of photons and of lepton-pairs, enabling an accurate determination of the nucleons and nuclei generalized parton distributions, and providing an access to the gravitational form factors of the energy-momentum tensor. Furthermore, positron beams offer the possibility of alternative tests of the Standard Model of particle physics through the search of a dark photon, the precise measurement of electroweak couplings, and the investigation of charged lepton flavor violation. This document discusses the perspectives of an experimental program with high duty-cycle positron beams at JLab.
The predominant source of nonlinearity in most existing accelerators are sextupoles, which introduce nonlinear resonances. When the horizontal tune of an accelerator is near such a resonance line ...(nν_{x}), stable fixed points (SFPs) may appear in the horizontal phase space to form a second closed orbit different from the “zero” closed orbit. The stable islands in phase space surrounding the SFPs are also referred as transverse resonance island “buckets” (TRIBs). However, the TRIBs are not always present near a resonance line in a storage ring. Necessary conditions for TRIBs formation will be discussed in this paper. A 6-GeV lattice with the horizontal tune near a third-order resonance at 3ν_{x}=50 is then designed for the Cornell Electron Storage Ring (CESR). After loading this lattice into CESR, the TRIBs are observed while adjusting the horizontal tune near the third-order resonance, consistent with particle tracking simulations. TRIBs rotation in the horizontal phase space are also experimentally demonstrated with adjustment of a sextupole knob. These results are in good agreement with the theoretical calculation.
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