On the number of bound states for weak perturbations of spin-orbit Hamiltonians

We give a variational proof of the existence of infinitely many bound states below the continuous spectrum for some weak perturbations of a class of spin-orbit Hamiltonians including the Rashba and Dresselhaus Hamiltonians

A Beam Separation and Collision Scheme for IP1 and IP5 at the LHC for Optics Version 6.1

In this report we describe the proposed beam separation and collision schemes for interaction points 1 and 5 in the LHC for optics version 6. The original proposal for optics version 5 was redesigned to be compatible with new requirements and the existing hardware. Contrary to the original scheme, in our scenario some magnets in the common part of the two rings are used to establish part of the crossing angle. However, individual control of the two beams remains fully possible. The necessary corrector strengths are significantly smaller and the aperture requirements less severe. Furthermore, this new scheme would allow to further increase the crossing angle, if required

Low Gradient, Large Aperture IR Upgrade Options for the LHC compatible with Nb-Ti Magnet Technology

The paper presents three different layout and optics solutions for the upgrade of LHC insertions using Nb-Ti superconducting quadrupoles. Each solution is the outcome of different driving design criteria: a) a compact triplet using low gradient quadrupoles; b) a triplet using low gradient quadrupoles of modular design, and c) a layout minimizing the B-max while using modular magnets. The paper discusses the different strategies and design criteria for the three solutions. It also discusses their relative advantages and disadvantages and identifies outstanding studies that need to be addressed in order to develop the solutions further. All cases assume that the first quadrupole magnet requires a smaller minimum aperture and therefore, can feature a slightly larger gradient than the remaining final focus quadrupole magnets

On the discrete spectrum of spin-orbit Hamiltonians with singular interactions

We give a variational proof of the existence of infinitely many bound states below the continuous spectrum for spin-orbit Hamiltonians (including the Rashba and Dresselhaus cases) perturbed by measure potentials thus extending the results of J.Bruening, V.Geyler, K.Pankrashkin: J. Phys. A 40 (2007) F113--F117.Comment: 10 pages; to appear in Russian Journal of Mathematical Physics (memorial volume in honor of Vladimir Geyler). Results improved in this versio

A Beam Separation and Collision Scheme for IP2 and IP8 at the LHC for Optics Version 6.1

In this report we describe the proposed beam separation and collision schemes for interaction points 2 (ALICE experiment) and 8 (LHCb) in the LHC for optics version 6. The original proposal for optics version 5 was redesigned to be compatible with new requirements and the existing hardware. Contrary to the original scheme, in our scenario some magnets in the common part of the two rings are used to establish part of the separation. However, individual control of the two beams remains fully possible. The necessary corrector strengths are significantly smaller and the aperture requirements less severe. Furthermore, this new scheme would allow to further increase the crossing angle, if required. To achieve this, the compensation scheme of the spectrometer magnets in IP2 and IP8 had to be redesigned and the implication of the desired alignment of these magnets was studied

Effect of external pressure on the magnetic properties of RRCoAsO (RR = La, Pr, Sm): a μ\muSR study

We report on a detailed investigation of the itinerant ferromagnets LaCoAsO, PrCoAsO and SmCoAsO performed by means of muon spin spectroscopy upon the application of external hydrostatic pressures $p$ up to $2.4$ GPa. These materials are shown to be magnetically hard in view of the weak dependence of both critical temperatures $T_{C}$ and internal fields at the muon site on $p$. In the cases $R$ = La and Sm, the behaviour of the internal field is substantially unaltered up to $p = 2.4$ GPa. A much richer phenomenology is detected in PrCoAsO instead, possibly associated with a strong $p$ dependence of the statistical population of the two different crystallographic sites for the muon. Surprisingly, results are notably different from what is observed in the case of the isostructural compounds $R$CoPO, where the full As/P substitution is already inducing a strong chemical pressure within the lattice but $p$ is still very effective in further affecting the magnetic properties.Comment: 8 pages, 9 figure

Influence of Machining Parameters on Heat Generation during Milling of Aluminum Alloys

Thin-walled components, i.e. fuselage frames of airplanes, are prone to an unstable process behavior during milling. Therefore, tools with a chamfer between the cutting edge and the flank face are often used for such machining tasks. During milling, the chamfered area comes into contact with the just cut surface. This contact leads to process damping forces and the induced heat into the workpiece in this contact zone is increased. Furthermore, the amount of induced heat depends on the process parameters. At certain spots on the machined surface this may lead to a local overheating, which can reduce stiffness significantly. When this occurs during milling of a thin-walled component, the component is often regarded as reject. In this paper, the influence of chamfers and process parameters on the induced heat into the workpiece is investigated experimentally. In addition, a simulation which predict the temperature in the workpiece in dependence of the process parameters is presented.Ministry of Economics, Labour and Transport of Lower Saxony/ZW3-80134969DFG/DE 447/90-