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| MOPCH186 | First Cool Down of the Juelich Accelerator Module Based on Superconducting Half-Wave Resonators | vacuum, radiation, shielding, COSY | 496 | ||||
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In the context of upgrading the existing proton and deuteron accelerator facility COSY at the Forschungszentrum Juelich, an accelerator module based on superconducting half wave resonators is prototyped. Due to beam dynamics, the requirements of cavity operation and a top-loading design for mounting, the cryostat had to be designed very compact and with a separate vacuum system for beam and insulation vacuum. These restricted requirements lead to very short cold-warm transitions in beam port region and to an unconventional design regarding to the shape of the cryostat vessel. This paper will review the design constraints, gives an overview of the ancillary parts of the module (cavities, tuner, etc.) and will present the results of the first cool-down experiments. Furthermore the future work will be presented.
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| MOPLS005 | A Staged Approach to LHC Commissioning | LHC, controls, CERN, vacuum | 538 | ||||
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After a brief reminder of the performance goals of the LHC, the overall strategy proposed for commissioning the machine with protons is presented. A thorough commissioning of the LHC hardware systems, presently ongoing, will lead into a staged approach for the first two years of operation with the beam, allowing both the complexity of the machine operation and the destructive power of the high intensity beams to be introduced in a controlled, incremental manner. The demands on the annual machine schedule are discussed, including the need to incorporate dedicated running for ions and proton-proton total cross section measurements. An important pre-commissioning milestone is the injection of the beam into a sector of the partially completed LHC; the motivation and tests planned are briefly summarised.
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| MOPLS012 | The LHC Sector Test | LHC, controls, injection, radiation | 559 | ||||
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The proposal to inject beam into a sector of the partially completed LHC is presented. The test will provide an important milestone, force preparation of a number of key systems, and allow a number of critical measurements with beam. The motivation for the test is discussed, along with the proposed beam studies, the radiation issues and the potential impact on ongoing installation. The demands on the various accelerator systems implicated are presented along with the scheduling of the preparatory steps, the test itself and the recovery phase.
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| TUPCH008 | Behavior of the BPM System During the First Weeks of SOLEIL Commissioning | SOLEIL, storage-ring, electron, synchrotron | 1007 | ||||
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SOLEIL, a new synchrotron light source built near Paris in France, is pioneering a new high resolution electron Beam Position Monitor (BPM) system to achieve stability of the beams at the micron level, as required for the beamlines. The same BPM system allows also measurement of the beam position in turn-by-turn mode for various machine physics studies. The system combines the high stability characteristic of multiplexed input channels and the flexibility of a digital system. Instrumentation Technologies developed the Libera module upon SOLEIL proposals and requirements. The performances of the system evaluated after the Booster and the storage ring commissioning will be presented.
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| TUPCH084 | Expected Signal for the TBID and the Ionization Chambers Downstream of the CNGS Target Station | target, proton, secondary-beams, LEFT | 1208 | ||||
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Downstream the carbon graphite target of the CNGS (CERN Neutrinos to Gran Sasso) facility at CERN it has been decided to install a secondary emission monitor called TBID (Target Beam Instrumentation Downstream) monitor to measure the multiplicities and the left/right as well as up/down asymmetries of secondary particles from target. Calculations show that the titanium windows used to close off the TBID vacuum tank might not withstand the highest beam intensities with small spot sizes expected at CNGS, in case the proton beam accidentally misses the 4-5 mm diameter target rods. Therefore it has been suggested to place two ionisation chambers as a backup for the TBID located left and right of the TBID monitors. Monte Carlo simulations with the particle transport code FLUKA were performed firstly to obtain the fluence of charged particles in the region of interest and secondly to estimate the induced radioactivity (noise) in this area. This allows to assess the actual signal/noise situation and thus to determine the optimal position (lateral displacement with respect to the beamline) of the ionisation chambers. This document presents the results of these calculations.
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| TUPCH092 | Commissioning of a New Digital BPM System for the PSI Proton Accelerators | proton, cyclotron, pick-up, controls | 1226 | ||||
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A new digital beam position monitor (DBPM) system has been developed and successfully tested at the PSI proton accelerators. The DBPM hardware consists of an analogue RF front-end (RFFE), a VMEbus backplane module (VBM), and the PSI VME PMC Carrier board (VPC). The RFFE combines the 2nd RF harmonic (101.26 MHz) beam signals of pickup coils with a 101.31 MHz pilot signal. The RFFE output signals are undersampled and down-converted to base-band (no analogue mixer) by ADCs and DDCs (Direct Digital Downconverters) on the VBM. The DDCs send the digitised beam and pilot signal amplitudes to a Virtex2Pro FPGA on the VPC board. The FPGA calculates the beam positions at different averaging rates, checks interlock limits, and provides triggered storage of beam position waveforms. Furthermore, the FPGA performs automatic gain control of voltage-controlled amplifiers (VCAs) of RFFE and VBM. By continuous normalisation of beam to pilot signal, nonlinearities and temperature drifts of the electronics are eliminated. Compared to the old analogue BPM electronics, the new DBPMs offer an increased dynamic range (0.2 μA to 2 mA instead of 5 μA to 2 mA) and larger bandwidth (10 kHz instead of 10 Hz).
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| TUPCH145 | The MUCOOL RF Program | RF-structure, linac, target, controls | 1358 | ||||
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Efficient muon cooling requires high RF gradients in the presence of high (~3T) solenoidal fields. The Muon Ionization Cooling Experiment (MICE) also requires that the x-ray production from these cavities is low, in order to minimize backgrounds in the particle detectors that must be located near the cavities. These cavities require thin Be windows to ensure the highest fields on the beam axis. In order to develop these cavities, the MUCOOL RF Program was started about 6 years ago. Initial measurements were made on a six-cell cavity and a single-cell pillbox, both operating at 805 MHz. We have now begun measurements of a 201 MHz pillbox cavity. This program has led to new techniques to look at dark currents, a new model for breakdown and a general model of cavity performance based on surface damage. The experimental program includes studies of thin Be windows, conditioning, dark current production from different materials, magnetic-field effects and breakdown. We will present results from measurements at both 805 and 201 MHz.
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| TUPCH183 | H2 Equilibrium Pressure in a NEG-coated Vacuum Chamber as a Function of Temperature and H2 Concentration | LHC, vacuum, injection, collider | 1444 | ||||
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Non Evaporable Getter (NEG) coating is used in the LHC room- temperature sections to ensure a low residual gas pressure for its properties of distributed pumping, low outgassing and desorption under particle bombardment; and to limit or cure electron cloud build-up due to its low secondary electron emission. In certain regions of the LHC, and in particular close to the beam collimators, the temperature of the vacuum chamber is expected to rise due to energy deposition from particle losses. Gas molecules are pumped by the NEG via dissociation on the surface, sorption at the superficial sites and diffusion into the NEG bulk. In the case of hydrogen, the sorption is thermally reversible, causing the residual pressure to increase with NEG temperature and amount of H2 pumped. Measurements were carried out on a stainless steel chamber coated with TiZrV NEG as a function of the H2 concentration and the chamber temperature, to estimate the residual gas pressure in the collimator regions for various LHC operation scenarios, corresponding to different particle loss rates and times between NEG regenerations. The results are presented in this paper and discussed.
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| WEIFI02 | Can the Accelerator Control System be Bought from Industry? | controls, LEFT, target, vacuum | 1916 | ||||
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This presentation is intended for project leaders and specialists, whose components depend on the control system, which is nearly everybody apart from control experts. The presentation will explain the basic concepts of an accelerator control system, illustrate the similarities and differences among the most popular packages, which are nicely disguised in acronyms such as EPICS, TANGO, TINE, DOOCS, COACK, XAL, CDEV, etc. and compare them to commercial control systems (DCS and SCADA) and LabView. The second part of the presentation will analyse whether a control system is in principle a component as any other and whether therefore in principle it should be bought eventually from a competent supplier like all the other components. It will identify the reasons why many people are reluctant to outsource control systems and illustrate this with some personal experiences and suggestions how to overcome these problems. The talk will conclude by showing how naively we have started a spin-off company* to commercialize the accelerator control system that we have developed, how we have found sustainable sources of business, and how we see the future in this and related markets.
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* Cosylab - Control System Laboratory, www.cosylab.com |
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Transparencies
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| THPCH026 | Parallel 3-D Space Charge Calculations in the Unified Accelerator Library | space-charge, simulation, synchrotron, AGS | 2835 | ||||
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The paper presents the integration of the SIMBAD space charge module in the UAL framework. SIMBAD is a Particle-in-Cell (PIC) code. Its 3-D parallel approach features an optimized load balancing scheme based on a genetic algorithm. The UAL framework enhances the SIMBAD standalone version with the interactive ROOT-based analysis environment and an open catalog of accelerator algorithms. The composite package addresses complex high intensity beam dynamics studies and has been developed as a part of the FAIR SIS 100 project.
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| THPCH185 | Planning and Logistics Issues Raised by the Individual System Tests during the Installation of the LHC | LHC, cryogenics, vacuum, superconducting-magnet | 3233 | ||||
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The running of individual system tests has to fit within tight constraints of the LHC installation planning and of CERN's accelerator activity in general. For instance, the short circuit tests of the power converters that are performed in situ restrict the possibility to work in neighbouring areas; much in the same way, the cold tests of the cryogenic distribution line involve safety access restrictions that are not compatible with the transport and installation of cryo-magnets or interconnect activities in the sector considered. Still, these individual system tests correspond to milestones that are required to ensure that we can continue with the installation of machine elements. This paper reviews the conditions required to perform the individual system tests and describe how the general LHC installation planning is organised to allocate periods for these tests.
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