A
bstract
In this paper we revisit the idea of measuring the magnetic dipole moments of the charm baryons and, in particular, of
Λ
c
+
by studying the spin precession induced by the strong effective ...magnetic field inside the channels of a bent crystal. We present a detailed sensitivity study showing the feasibility of such an experiment at the LHC in the coming years.
A
bstract
In this paper we discuss the possibility of measuring the anomalous magnetic and electric dipole moments of the
τ
lepton. The method consists in studying the spin precession induced by the ...strong effective magnetic field inside channels of a bent crystal with a dedicated setup at the CERN Large Hadron Collider.
In this paper, we discuss the theoretical framework and the experimental measurements of the magnetic moment of the charmed baryons. We first review the theoretical predictions of the
Λ
c
+
magnetic ...moment and show that the measurements of the magnetic moments of other charmed baryons, such as
Ξ
c
, allow to perform detailed spectroscopy studies. The magnetic moment of the charm quark can be determined using radiative charmonium decay, which can be compared to the
Λ
c
+
magnetic moment within theoretical models. The present results show a tension with majority of theoretical predictions. The magnetic moment of the charmed baryons could potentially be measured directly, using bent-crystal experiments at LHC. The possibility to measure precisely the magnetic moments of charmed baryons needs precise measurement of their polarisation and weak decay parameters. In this paper, we revisit the formalism of the angular analysis needed for these measurements and make a detailed evaluation of initial polarisation of deflected
Λ
c
baryons as a function of crystal orientation. We found a special orientation of the crystal that gives the opportunity to measure the
Λ
c
dimensionless electric dipole moment almost with the same precision as its
g
-factor, which is more than an order of magnitude more efficient than suggested before.
The article describes a method for producing semi-finished products from a copper alloy of the Cu–Ni–Cr–Si system for electrical purposes through the radial-shear rolling (RSR). From the Cu–Ni–Cr–Si ...alloy by hot deformation, rods with a diameter of 20 mm were obtained, which were then heat treated with quenching and aging. A detailed analysis of the microstructure and properties (mechanical and electrical) of the obtained samples was carried out after RSR and after heat treatment (HT). After RSR, material hardening occurs due to shear deformations forming a gradient structure with grain sizes varying from 8.22 μm to 15.95 μm between the surface and the center of the rod. The microstructure and mechanical property analysis showed that after heat treatment, the alloy is thermally hardened due to the precipitation of Ni2Si and Cr3Si particles uniformly distributed in the sample volume in the form of fine inclusions with an average size of 0.56–0.65 μm. After heat treatment, the alloy enhanced its mechanical properties (ultimate tensile strength (UTS) ~ 700–750 MPa, yield strength (YS) ~ 557–606 MPa, and elongation between 17 and 22%) and its electrical conductivity of 45.17% IACS from the 30.52% IACS of the RSR material. The improved mechanical properties of the heat-treated material are due to the different strength contributions mainly coming from dislocations and precipitates. The electrical conductivity improvement after the heat treatment is related to the dislocation density reduction and the increase in grain boundary misorientation due to the recrystallization phenomenon giving rise to a lower number of boundaries but with a twinning character. Thus, the RSR method offers a new industrial alternative for the production of semi-finished products from a Cu–Ni–Cr–Si alloy in the form of rods with diameters ranging from 10 to 55 mm.
•Radial shear rolling can produce copper rods of different diameters at an industrial scale.•The thermomechanical process using radial shear rolling gives rise to a heterogeneous material.•Aging treatment after radial shear rolling produces a remarkable combination of strength, ductility, and electrical conductivity.•Dislocations annihilation and grain boundaries misorientation change help to improve the material electrical conductivity.
Several studies are on-going at CERN in the framework of the Physics Beyond Collider study group, with main aim of broadening the physics research spectrum using the available accelerator complex and ...infrastructure. The possibility to design a layout that allows fixed-target experiments in the primary vacuum of the CERN Large Hadron Collider (LHC), without the need of a dedicated extraction line, is part of these studies. The principle of the layouts presented in this paper is to deflect beam halo protons on a fixed-target placed in the LHC primary vacuum, by means of the channeling process in bent crystals. Moreover, the presence of a second bent crystal adjacent to the target opens a unique opportunity for the first direct measurement of electric and magnetic dipole moments of short-lived baryons. Two possible layouts are reported, together with a thorough evaluation on their expected performance and impact on LHC operations.
The effect of high-temperature radial-shear rolling (RSR) on the strain and stress distributions in the cross-sections of processed rods has been studied using finite element method simulation for ...the industrial 7075 alloy and compared with that for the new Al7Zn2.8Mg0.7Ni0.55Fe0.2Zr alloy. The simulation has revealed a gradient strain distribution along the cross-section of the processed rods for both alloys. The lowest stress has been observed in the central part of the rods, whereas the peripheral zones have had the highest strain with a factor of more than 1.5. For both alloys, the maximum true strain localized in the peripheral zones of the rods (~10) has proven to be substantially higher than the true strain (~2.1) caused by change in the overall (linear) dimensions of the rods. The results of numerical simulation of the stress and strain distributions have been in a good agreement with the as-deformed structure. For example, we have observed the formation of a gradient structure consisting of deformed fibrous grains in the central parts of the rods (in the vicinity of their axes) whereas in the middle of rod diameter and in the surface layers that are exposed to the highest stress and strain the structure contained more equiaxed and finer grains formed during dynamic recrystallization. The results of uniaxial tensile tests have revealed that the mechanical properties of the 7075 alloy (UTS ~ 390 MPa, YS ~ 280 MPa and δ ~ 9.9%) after RSR are comparable to those of the new alloy the microstructure of which additionally contains fine intermetallic particles. Thus, radial-shear rolling can be considered as an efficient industrial technology of high-strength aluminum alloys allowing one to achieve a combination of high strength and ductility in as-processed materials with a gradient grain structure.
The Russian Federation is one of many countries that have signed the Montreal Protocol and Pan-European Forest Process. These initiatives are aimed at harmonizing national forest inventory systems ...with criteria and indicators for sustainable forest management. In Russia, the classification of forest type is at the heart of national forest inventory systems. For various historical reasons, Russian scientific advancements in the field of forest typology remain little known in the rest of the world. This paper is aimed at addressing this deficiency. Here, we provide an overview of the main trends in the field of forest typology studies in the previous political states of the Russian Empire, the Soviet Union, and the Russian Federation from the end of the nineteenth century to the beginning of the twenty-first century. We detail the principles that formed the basis of the most significant forest type classifications. We also perform similarity and differences analyses comparing approaches used by members of different scientific schools in the field of forest typology. The historical relationship between ecological, phytocoenotic, genetic, and dynamic forest type classifications are discussed as well as the reasons for the prevalence of certain forest type classifications in different regions of Russia.
The studies into optimization of rare-metal ore processing using the mineralogical and process characteristics of the ore and by means of controlled combination of ore pre-treatment and gravity ...separation are presented. Grindabilties of low-grade loparite ore and current production material are compared, general patterns of generation of productive class –0.63 + 0.07 mm are found. Controlled grinding allows gravity separation of low-grade loparite ore at the level of performance of standard-grade crude ore processing. Regarding promising deposits of rare metals in Eastern Siberia, the authors analyze and select the optimal conditions of gravity separation in combination with spiral separation, table concentration, centrifugal concentration and high-power magnetic separation. The mixed-type gravity/magnetic separation technology with production of columbite and zirconium concentrates is developed.
Control of any robotic system cannot be executed without a preliminary solution of the inverse kinematic problem. This problem implies determining the control actions of the actuators required to ...perform a given motion trajectory and embedded into the control system. The current study considers the inverse kinematics of a hybrid (parallel-serial) manipulator with five degrees-of-freedom (5-DOF). The article first briefly describes the manipulator structure, which includes 3-DOF parallel and 2-DOF serial parts, and then explains an algorithm for solving the inverse kinematics. The algorithm relies on the product-of-exponentials (PoE) formula applied to an equivalent manipulator with a serial structure. The proposed algorithm results in a closed-form solution with no assumptions about the manipulator geometry. A case study confirms the algorithm correctness. The method for solving the inverse kinematic problem can be adapted for other hybrid manipulators.
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