Septa and Distributor Developments for H- Injection into the Booster from LINAC4

The construction of Linac4 requires the modification of the existing injection system of the CERN PS Booster. A new transfer line will transport 160 MeV H- ions to this machine. A system of 5 pulsed magnets (BIDIS) and 3 vertical septa (BISMV) will distribute and inject the Linac pulses into the four-vertically separated Booster rings. Subsequently the beam will be injected horizontally, using a local bump created with bumpers (BS magnets) to bring the injected H- beam together with the orbiting proton beam onto the stripper foil. To accommodate the injected H- beam, the first of the BS magnets will have to be a septum-like device, deflecting only the orbiting beam. This paper highlights the requirements and technical issues and describes the solutions to be adopted for both the BIDIS and BISMV. The results of initial prototype testing of the BIDIS magnet will also be presented

Operational considerations for the PSB H- Injection System

For the LINAC4 project the PS Booster (PSB) injection system will be upgraded. The 160 MeV Hbeam will be distributed to the 4 superimposed PSB synchrotron rings and horizontally injected by means of an H- charge-exchange system. Operational considerations for the injection system are presented, including expected beam losses from unwanted field stripping of H- and excited H0 and foil scattering, possible injection failure cases and expected stripping foil lifetimes. Loading assumptions for the internal beam dumps are discussed together with estimates of doses on various components

Layout considerations for the PSB H- injection system

The layout of the PSB H- injection system is described, including the arguments for the geometry and the required equipment performance parameters. The longitudinal positions of the main elements are specified, together with the injected and circulating beam axes. The assumptions used in determining the geometry are listed

Spatial Heterogeneity in the Abundance and Fecundity of Arctic Mosquitoes

The abundance of mosquitoes is strongly influenced by biotic and abiotic factors that act on the immature (aquatic) and adult (terrestrial) life stages. Rapid changes in land use and climate, which impact aquatic and terrestrial mosquito habitat, necessitate studying the ecological mechanisms, and their interplay with the changing environment, that affect mosquito abundance. These data are crucial for anticipating how environmental change will impact their roles as pests, disease vectors, and in food webs. We studied a population of Arctic mosquitoes (Aedes nigripes, Diptera: Culicidae) in western Greenland, a region experiencing rapid environmental change, to quantify spatial variation in adult abundance and reproduction. Using sweep nets, we collected about sevenfold more mosquitoes within the town of Kangerlussuaq and within a low‐elevation tundra valley compared to three other tundra locations. Dissections of adult female mosquitoes revealed that only 17% were gravid overall, with a range of 7–43% among sites. If gravid, mosquitoes matured an average of 60 eggs per individual—more in larger females. We found no indication of autogenous egg development. Analyses using our field data indicated that spatial variation in adult fecundity and survival of immatures could each account for a 10‐fold range in the per capita growth of mosquito populations. The availability of vertebrate hosts and aquatic habitat is changing in many parts of the Arctic and can be expected to influence Arctic mosquito abundance. In the Arctic, and elsewhere, life‐history data from natural populations of mosquitoes will significantly aid in understanding controls on the abundance of these globally ubiquitous insects

Development of an Eddy Current Septum for LINAC4

A linear accelerator (linac) is the first stage of the CERN accelerator complex. The linac defines the beam quality for subsequent stages of acceleration and the reliability has to be high as a fault of the linac shuts down all other machines. The existing linacs at CERN were designed 30 or more years ago: recent upgrades allowed the linacs to reach LHC requirements but also showed that they are at the limit of their brightness and intensity capabilities. A replacement Superconducting Proton Linac (SPL) has been proposed; the initial part of the SPL is termed LINAC4. The LINAC4 injection bump would be made up of a set of four pulsed dipole magnets; the first of these magnets (BS1) must act as a septum with a thin element dividing the high-field region of the circulating beam from the field-free region through which injected $H^{-}$ beam must pass. The initial specifications for BS1 required; a deflection of 66 mrad at 160 MeV, achieved with a peak field of 628 mT and a length of 250 mm: the field fall time was $40 \mu$s with a flattop of at least $100 \mu$s. The ripple of the flattop should be below ±1%. This paper discusses the design of an eddy current septum for BS1

160 MeV H−H^- Injection into the CERN PSB

The H- beam from the proposed LINAC4 will be injected into the four existing rings of the PS Booster at 160 MeV. A substantial upgrade of the injection region is required, including the modification of the beam distribution system and the construction of a new H- injection system. This paper discusses beam dynamics and hardware requirements and presents the results of optimisation studies of the injection process for different beam characteristics and scenarios. The resulting conceptual design of the injection region is presented, together with the main hardware modifications and performance specifications

Distinguishing blaKPC -gene-containing IncF plasmids from epidemiologically related and unrelated Enterobacteriaceae based on short- and long-read sequence data

BACKGROUND: Limited information is available on whether blaKPC -containing plasmids from isolates in a hospital outbreak can be differentiated from epidemiologically unrelated blaKPC-containing plasmids based on sequence data. This study aimed to evaluate the performance of three approaches to distinguish epidemiologically related from unrelated blaKPC-containing pKpQiL-like IncFII(k2)-IncFIB(pQiL) plasmids. METHOD: Epidemiologically related isolates, were short- and long-read whole genome sequenced. A hybrid assembly was performed and plasmid sequences were extracted from the assembly graph. Epidemiologically unrelated plasmid sequences were extracted from the GenBank. Pairwise comparisons were performed of epidemiologically related and unrelated plasmids based on SNP differences using snippy, phylogenetic distance using Roary and using a similarity index that penalizes size differences between plasmids (Stoesser-index). The percentage of pairwise comparisons misclassified as genetically related or as clonally unrelated was determined using different genetic thresholds for genetic relatedness. RESULTS: The ranges in number of SNP differences, Roary phylogenetic distance, and Stoesser-index overlapped between the epidemiologically related and unrelated plasmids. When using a genetic similarity threshold that classified 100% of epidemiologically related plasmid pairs as genetically related, the percentages of plasmids misclassified as epidemiologically related ranged from 6.7% (Roary) to 20.8% (Stoesser-index). DISCUSSION: Although epidemiologically related plasmids can be distinguished from unrelated plasmids based on genetic differences, blaKPC-containing pKpQiL-like IncFII(k2)-IncFIB(pQiL) plasmids show a high degree of sequence similarity. The phylogenetic distance as determined using Roary showed the highest degree of discriminatory power between the epidemiologically related and unrelated plasmids

A Novel Eddy Current Septum Magnet for SPS Extraction towards LHC and CNGS

A new East Fast-Extraction System is under construction in the SPS, to supply particles with a maximum batch length of 7.8 us and 10.5 us to the LHC and to CNGS (CERN Neutrino to Gran Sasso), respectively. The extraction septum magnets actually used at the SPS have been designed for slow extraction over several seconds, have large cooling and electrical power demands and need frequently maintenance in a high radiation environment. A fast system of only 250 us pulse duration has therefore been developed, using a half-sine excitation pulse with a superimposed third harmonic. The short pulse duration requires very thin magnetic yoke laminations, which can not easily be stamped and stacked. Profiting from a development for the LHC beam dump kicker magnets, the yoke is therefore built-up from tape-wound cylindrical cores, employing 50 um thick Si-steel tape. Thirty two cores are stacked longitudinally to produce a yoke of 3.2 meter length. The aperture is cut radial into each cylinder. The cores are radial compressed by spring-loaded pistons inserted in strong stainless-steel frames to provide mechanical stability. The 5+1 mm thick copper/iron septum is separated from the excitation current loop and acts as a passive eddy current screen. This allows separating the vacuum of the magnet from that of the circulating-beam channel, avoiding the need of using UHV material. This paper presents the magnet and generator prototype design as well as simulation and measurement results

Initial results from beam commissioning of the LHC beam dump system

Initial commissioning of the LHC beam dump system with beam took place in August and September 2008. The preparation, setting-up and the tests performed are described together with results of the extractions of beam into the dump lines. Analysis of the first detailed aperture measurements of the extraction channels and kicker performance derived from dilution sweep shapes are presented. The performance of the other equipment subsystems is summarised, in particular that of the dedicated dump system beam instrumentation