Emittance Growth at LHC Injection from SPS and LHC Kicker Ripple

Fast pulsed kicker magnets are used to extract beams from the SPS and inject them into the LHC. The kickers exhibit time-varying structure in the pulse shape which translates into small offsets with respect to the closed orbit at LHC injection. The LHC damper systems will be used to damp out the resulting betatron oscillations, to keep the growth in the transverse emittance within specification. This paper describes the results of the measurements of the kicker ripple for the two systems, both in the laboratory and with beam, and presents the simulated performance of the transverse damper in terms of beam emittance growth. The implications for LHC operation are discussed

Abort Gap Cleaning using the Transverse Feedback System: Simulation and Measurements in the SPS for the LHC Beam Dump System

The critical and delicate process of dumping the beams of the LHC requires very low particle densities within the $3 \mu$s of the dump kicker rising edge. High beam population in this so-called 'abort gap' might cause magnet quenches or even damage. Constant refilling due to diffusion processes is expected which will be counter-acted by an active abort gap cleaning system employing the transverse feedback kickers. In order to assess the feasibility and performance of such an abort gap cleaning system, simulations and measurements with beam in the SPS have been performed. Here we report on the results of these studies

FEATURE RELEVANCE ANALYSIS FOR 3D POINT CLOUD CLASSIFICATION USING DEEP LEARNING

3D point clouds acquired by laser scanning and other techniques are difficult to interpret because of their irregular structure. To make sense of this data and to allow for the derivation of useful information, a segmentation of the points in groups, units, or classes fit for the specific use case is required. In this paper, we present a non-end-to-end deep learning classifier for 3D point clouds using multiple sets of input features and compare it with an implementation of the state-of-the-art deep learning framework PointNet++. We first start by extracting features derived from the local normal vector (normal vectors, eigenvalues, and eigenvectors) from the point cloud, and study the result of classification for different local search radii. We extract additional features related to spatial point distribution and use them together with the normal vector-based features. We find that the classification accuracy improves by up to 33% as we include normal vector features with multiple search radii and features related to spatial point distribution. Our method achieves a mean Intersection over Union (mIoU) of 94% outperforming PointNet++’s Multi Scale Grouping by up to 12%. The study presents the importance of multiple search radii for different point cloud features for classification in an urban 3D point cloud scene acquired by terrestrial laser scanning

LHC Abort Gap Cleaning with the Transverse Damper

In the Large Hadron Collider, LHC, particles not captured by the RF system at injection or leaking out of the RF bucket may quench the superconducting magnets during beam abort. The problem, common to other superconducting machines, is particularly serious for the LHC due to the very large stored energy in the beam. For the LHC a way of removing the unbunched beam has been studied and it uses the existing damper kickers to excite resonantly the particles travelling along the abort gap. In this paper we describe the results of simulations performed with MAD X for various LHC optics configurations, including the estimated multipolar errors

N-Methylimidazole Promotes The Reaction Of Homophthalic Anhydride With Imines

The addition of N-methylimidazole (NMI) to the reaction of homophthalic anhydride with imines such as pyridine-3-carboxaldehyde-N-trifluoroethylimine (9) reduces the amount of elimination byproduct and improves the yield of the formal cycloadduct, tetrahydroisoquinolonic carboxylate 10. Carboxanilides of such compounds are of interest as potential antimalarial agents. A mechanism that rationalizes the role of NMI is proposed, and a gram-scale procedure for the synthesis and resolution of 10 is also described

Progress with the Upgrade of the SPS for the HL-LHC Era

The demanding beam performance requirements of the High Luminosity (HL-) LHC project translate into a set of requirements and upgrade paths for the LHC injector complex. In this paper the performance requirements for the SPS and the known limitations are reviewed in the light of the 2012 operational experience. The various SPS upgrades in progress and still under consideration are described, in addition to the machine studies and simulations performed in 2012. The expected machine performance reach is estimated on the basis of the present knowledge, and the remaining decisions that still need to be made concerning upgrade options are detailed.Comment: 3 p. Presented at 4th International Particle Accelerator Conference (IPAC 2013

Frontier in three-dimensional cave reconstruction—3D meshing versus textured rendering

Underground caves and their specific structures are important for geomorphological studies. This paper investigates the capabilities of a new modelling approach advanced for true-to-life three-dimensional (3D) reconstruction of cave with full resolution scan relative to 3D meshing. The cave was surveyed using terrestrial laser scanner (TLS) to acquire high resolution scans. The data was processed to generate a 3D-mesh model and textured 3D model using sub-sampled points and full resolution scan respectively. Based on both point and solid surface representation, comparative analysis of the strengths and weaknesses of the two approaches were examined in terms of data processing efficiency, visualization, interactivity and geomorphological feature representation and identification. The result shows that full scan point representation offers advantage for dynamic visualization over the decimated xyz point data because of high density of points and availability of other surface information like point normal, intensity and height which can be visualized in colour scale. For the reconstructed surface, mesh model is better with respect to interactivity and morphometric but 3D rendering shows superiority in visual reality and identification of micro detail of features with high precision. Complementary use of the two will provide better understanding of the cave, its development and processes

A Natural Love of Natural Products

Recent research on the chemistry of natural products from the author’s group that led to the receipt of the ACS Ernest Guenther Award in the Chemistry of Natural Products is reviewed. REDOR NMR and synthetic studies established the T-taxol conformation as the bioactive tubulin-binding conformation, and these results were confirmed by the synthesis of compounds which clearly owed their activity or lack of activity to whether or not they could adopt the T-taxol conformation. Similar studies with the epothilones suggest that the current tubulin-binding model needs to be modified. Examples of natural products discovery and biodiversity conservation in Suriname and Madagascar are also presented, and it is concluded that natural products chemistry will continue to make significant contributions to drug discovery. My first real exposure to natural products chemistry came in my third and final year as an undergraduate at Cambridge University, when I attended a course of lectures on the chemistry of natural products by the Nobel Prize-winning chemist Sir Alexander Todd (later to become Lord Todd). The lectures included many references to his own work in the field, with stories of his early work on the structure of cholesterol, th