Beam collimation and control in the LHC high energy injectors

The design and construction of new injectors will allow to boost the luminosity of the LHC. Two consecutive machines capable to inject into the LHC ring at 1 TeV are being considered. Based only on the expected performance of the injectors, the beam loss handling in these high intensity machines will be a challenge and the introduction of collimation systems seems necessary. The need to reduce the beam losses and allow an efficient collimation system has to be implemented from the beginning of the design. The energy ramping in stages requires different approaches for removing the proton halo. Some studies are still necessary to define the hardware. The study performed in this paper as well as the conclusions will only slightly differ when applied to another scenario

Commissioning and experience in stripping, filtering and measuring the 4.2 MeV/u lead ion beam at CERN Linac 3

The new CERN Heavy Ion Linac (Linac3) accelerates a Pb27+ beam to 4.2 MeV/u. The beam is then stripped to Pb53+ by a carbon foil, and, after stripping, a 12 m filter line prepares the beam for the injection into the Proton Synchrotron Booster (PSB). The filter line eliminates the unwanted charge states, checks the beam quality (energy, energy spread, transverse emittance and intensity), and finally transports the beam in the lines leading to the PSB. The paper summarises the transverse beam dynamics of the line, and reports on its commissioning, especially focusing on the experiments that led to the stripper choice, and on the measurements performed with a specially developed single pulse moperational experience is also reported

Topology of the polarization field in ferroelectric nanowires from first principles

The behaviour of the cross-sectional polarization field is explored for thin nanowires of barium titanate from first-principles calculations. Topological defects of different winding numbers have been obtained, beyond the known textures in ferroelectric nanostructures. They result from the inward accommodation of the polarization patterns imposed at the surface of the wire by surface and edge effects. Close to a topological defect the polarization field orients out of the basal plane in some cases, maintaining a close to constant magnitude, whereas it virtually vanishes in other cases.Comment: 4 pages, 3 figure

A Collimation Experiment with Protons at 120 GeV

We present the preliminary results of a two-stage collimation experiment made with a 120 GeV coasting proton beam in the SPS at CERN

Genetic relatedness and taxonomy in closely related species of Hedysarum (Fabaceae)

A multidisciplinary study, engaging morphological, carpological and molecular data, has been performed to investigate the genetic relatedness and taxonomic boundaries of the close species Hedysarum gmelinii, H. setigerum and H. chaiyrakanicum (Fabaceae) with overlapped distribution areas in southern Siberia. The diagnostic features of these legume species are analyzed and discussed, including their macro- and micromorphological characteristics, seed coat ornamentation and inter-simple sequence repeat (ISSR) profiles. The morphometric features, pod and seed microsculpture traits of H. chaiyrakanicum and the ISSR patterns of the three species have been determined for the first time. Sprout, leaf, calyx, corolla, and stem rachis measurements, leaflet indumentum type and ISSR patterns significantly discriminate H. chaiyrakanicum from the other two species, whereas plant height, lengths of stem and leaf, and length and width of leaflet show opposite ranges of variation for H. gmelinii and H. setigerum though none of them is reliable in species identification. Ornamentation of seed coat and ISSR patterns does not differ significantly in the species. Therefore, our study supports the separate taxonomic treatment of H. chaiyrakanicum and the subordination of the cryptic species H. setigerum within H. gmelinii

Physical properties of seven binary and higher-order multiple OB systems

Analyses of multi-epoch, high-resolution (~ 50000) optical spectra of seven early-type systems provided various important new insights with respect to their multiplicity. First determinations of orbital periods were made for HD 92206C (2.022 d), HD 112244 (27.665 d), HD 164438 (10.25 d), HD 123056A (~ 1314 d) and HD 123056B (< 2 d); the orbital period of HD 318015 could be improved (23.445975 d). Concerning multiplicity, a third component was discovered for HD 92206C by means of He I line profiles. For HD 93146A, which was hitherto assumed to be SB1, lines of a secondary component could be discerned. HD 123056 turns out to be a multiple system consisting of a high-mass component A (~ O8.5) displaying a broad He II 5411 A feature with variable radial velocity, and of an inner pair B (~ B0) with double He I lines. The binary HD 164816 was revisited and some of its system parameters were improved. In particular, we determined its systemic velocity to be -7 km/s, which coincides with the radial velocity of the cluster NGC 6530. This fact, together with its distance, suggests the cluster membership of HD 164816. The OB system HD 318015 (V1082 Sco) belongs to the rare class of eclipsing binaries with a supergiant primary (B0.5/0.7). Our combined orbital and light-curve analysis suggests that the secondary resembles an O9.5III star. Our results for a limited sample corroborate the findings that many O stars are actually massive multiple systems.Comment: 16 pages, 16 figures, to appear in Astronomy and Astrophysic

Cascade Simulations for the LHC Betatron Cleaning Insertion

A cascade calculation is done in the IR7 betatron cleaning insertion of LHC. It uses a detailed map of the primary losses and an accurate model of the straight section. One aim is to design a compact shielding which fits in the tight section of the tunnel. The same study allows to define radiation hardness properties of the equipment to be installed in the section and to locate areas of low activi ty for the installation of sensitive equipment

Fast Ramping Superconducting Magnet Design Issues for Future Injector Upgrades at CERN

An upgrade of the LHC injection chain, and especially the sequence of PS and SPS, up to an extraction energy of 1 TeV, is one of the steps considered to improve the performance of the whole accelerator complex. The magnets for this upgrade require central magnetic field from 2 T (for a PS upgrade) to 4.5 T (for an SPS upgrade), for which superconducting magnets are a candidate. Due to the fast field sweep rate of the magnets (from about 1.5 T/s to 2.5 T/s), internal heating from eddy and persistent current effects (AC loss) must be minimized. In this paper we discuss a rationale for the design and optimization of fast ramped superconducting accelerator magnets, specifically aimed at the LHC injectors. We introduce a design parameter, the product of bore field and field ramp-rate, providing a measure of the magnet performance, and we apply it to choose the design range for a technology demonstration magnet. We finally discuss the dependence of key design parameters on the bore field and the bore diameter, to provide an approximate scaling and guidelines for critical R&D