291 research outputs found
Options for upgrading the intensity of the CERN lead pre-injector ion source
CERN's heavy ion pre-injector has been in service since 1994, providing lead ions for fixed target collisions at 177 GeV per nucleon in the SPS. In the LHC era, heavy ion collisions require an increase in the beam brightness, compared to the present injector system of Linac 3, Proton Synchrotron Booster and the Proton Synchrotron. Stacking and cooling ions in a Low Energy Ion Ring should find the largest part of this increase. However, further improvements can be envisaged by upgrading the pre-injector and source. The performance and limitations of the present source and Linac 3 will be discussed, and options for increasing the source brightness will be presented. These options consist of upgrades of the ECR Source to higher frequencies, or its replacement with a Laser Ion Source
Studies on ECR4 for the CERN ion programme
The CERN heavy ion community, and some other high energy physics experiments, are starting to demand other ions, both heavy and light, in addition to the traditional lead ions. Studies of the behaviour of the afterglow for different operation modes of the ECR4 at CERN have been continued to try to understand the differences between pulsed afterglow and continuous operation, and their effect on ion yield and beam reproducibility. The progress in adapting the source and ion beam characteristics to meet the new demands will be presented, as will new information on voltage holding problems in the extraction
Phase Rotation, Cooling And Acceleration Of Muon Beams: A Comparison Of Different Approaches
Experimental and theoretical activities are underway at CERN with the aim of
examining the feasibility of a very-high-flux neutrino source. In the present
scheme, a high-power proton beam (some 4 MW) bombards a target where pions are
produced. The pions are collected and decay to muons under controlled optical
condition. The muons are cooled and accelerated to a final energy of 50 GeV
before being injected into a decay ring where they decay under well-defined
conditions of energy and emittance.
We present the most challenging parts of the whole scenario, the muon
capture, the ionisation-cooling and the first stage of the muon acceleration.
Different schemes, their performance and the technical challenges are compared.Comment: LINAC 2000 CONFERENCE, paper ID No. THC1
A wireless robotic manipulator for semiconductor manufacturing equipment
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1997.Silicon wafer processing is an extremely refined and sensitive operation. Processing often takes place in clean rooms filtered to better than class 1. However even under these precautions, particle contamination still causes failures in the microchips produced in these environments. One source of these contaminants is the production equipment itself. Particularly, the wire carriers connecting the robots can shed micro particles which are deposited onto the wafers in process. The wires within these carriers also possess a considerable failure rate which causes machine down time and contamination of the environment due to the repair operation. These combined factors illustrate the need to minimize the use of wire carriers. The solution to these problems is the concept of the wireless robot. The wireless robot uses inductive power transfer and optical communication to operate the end effector of the robot. This takes advantage of the fact that for many types of production equipment, the robots only need to execute more complex motions at discrete locations. In its overall operation, the robot is positioned in front of an operation station where a pair electromagnetic coils would be aligned. The primary coil would be fixed to the station and the secondary coil would be attached to the robotic manipulator. The primary coil would be charged by a high frequency AC supply, and the property of electromagnetic induction would cause a similar voltage to be produced in the secondary coil. This voltage would then be supplied to the electronics of the manipulator as a power source. Robot control would be achieved through the use of optical transfer rather than a hardwired voltage transfer. This technique is similar to well known processes used in fiber optics, however in this process the transfer median is an air gap rather than a fiber optic cable. This design calls for the use of only one way transmission where the transmitters are on the base and the receptors are on the robot. Two way transmission for feedback is possible and available for future use. This design also lends itself to a variety of other applications including factory automation robots and other environments in which operation is required in discrete locations or sensitive environments.by Jevin E. Scrivens.S.M
Tests of the CERN Proton Linac Performance for LHC-Type Beams
As the pre-injector of the LHC injector chain, the proton linac at CERN is
required to provide a high-intensity (180mA) beam to the Proton Synchrotron
Booster. The results of measurements at this intensity will be presented.
Furthermore, the linac is now equipped with bunch shape monitors from INR,
Moscow, which have allowed the comparison of the Alvarez tank RF settings with
simulations.Comment: LINAC 2000, TUC14, 3 pages, 5 figure
Under-representation of males in the early years: the challenges leaders face
This article investigates why there appears to be an under-representation of males in comparison to their female colleagues in the Early Years (EY) sector, and the perception of male teachers progressing more quickly to leadership positions when they do enter this context. Using case studies of final year male students on an Initial Teacher Training (ITT) undergraduate degree course at one university, we attempt to analyse data on male under-representation in Early Years against contemporary theories of identity, power and leadership. Questionnaires and interviews were conducted with the male sample group and male senior leaders in primary schools to gain an overview as to the leadership support they needed and provided. Our tentative findings suggested that male trainees are happy to work in an Early Years context and take leadership positions, but the challenge for leaders is that male trainees require strong leadership mentoring processes to help overcome perceived contextual barriers
Going places
Journeys. We all make them. Often they take us to exotic places. Sometimes they take us even further. They might take us through time. Or they might take us into a new way of life. There are times too, when we go all over the world and back again only to find that home is, after all, where itâs all happening.
This book contains stories about many different types of journey. We hope you will enjoy travelling into it and finding a world that suits you
A combined approach for comparative exoproteome analysis of Corynebacterium pseudotuberculosis
Background: Bacterial exported proteins represent key components of the host-pathogen interplay. Hence, we
sought to implement a combined approach for characterizing the entire exoproteome of the pathogenic
bacterium Corynebacterium pseudotuberculosis, the etiological agent of caseous lymphadenitis (CLA) in sheep and
goats.
Results: An optimized protocol of three-phase partitioning (TPP) was used to obtain the C. pseudotuberculosis
exoproteins, and a newly introduced method of data-independent MS acquisition (LC-MSE) was employed for
protein identification and label-free quantification. Additionally, the recently developed tool SurfG+ was used for in
silico prediction of sub-cellular localization of the identified proteins. In total, 93 different extracellular proteins of
C. pseudotuberculosis were identified with high confidence by this strategy; 44 proteins were commonly identified
in two different strains, isolated from distinct hosts, then composing a core C. pseudotuberculosis exoproteome.
Analysis with the SurfG+ tool showed that more than 75% (70/93) of the identified proteins could be predicted as
containing signals for active exportation. Moreover, evidence could be found for probable non-classical export of
most of the remaining proteins.
Conclusions: Comparative analyses of the exoproteomes of two C. pseudotuberculosis strains, in addition to
comparison with other experimentally determined corynebacterial exoproteomes, were helpful to gain novel
insights into the contribution of the exported proteins in the virulence of this bacterium. The results presented
here compose the most comprehensive coverage of the exoproteome of a corynebacterial species so far
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