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| MOPC009 | Experiments on LHC Long-Range Beam-Beam Compensation and Crossing Schemes at the CERN SPS in 2004 | emittance, simulation, dynamic-aperture, resonance | 686 | ||
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Experiments with two prototype long-range beam-beam compensators (current-carrying wires) during the 2004 CERN SPS run explored the efficiency of a proposed long-range beam-beam compensation for the LHC. In addition, the SPS compensators were also used to 'simulate' the effect of different planes of crossing at two LHC interaction points. We present the experimental results and compare them with computer simulations.
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| TPAP002 | Summary of Recent Studies of Cryosorbers for LHC Long Straight Sections | vacuum, collider, injection, electron | 791 | ||
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Funding: This work was supported by CERN AT Division vacuum group. |
The vacuum chamber inside some cryogenic elements in the LHC long straight sections will have cold bore (CB) at 4.5K and a beam screen (BS) at temperature between 5 and 20K. The gas molecules desorbed due to photons and electrons will pass through the slots on the BS to the shadowed part between the CB and BS. All desorbed gases except H2 could be adsorbed on the CB and BS but a cryosorber is required to pump H2. The new types of anodized aluminum, porous copper and charcoal-based materials were developed and studied to cryopump H2 at temperatures between 10 and 20K. The advantages and disadvantages of cryosorbers and technological problems of development of new similar cryosorbers were defined. The vacuum parameters of LHC vacuum chamber prototypes with charcoal and two types of carbon fiber cryosorbers were measured. The dynamic pressure behavior at BS temperature oscillations was studied for BS with woven carbon fiber to predict the dynamic pressure at nonstandard or transient regimes of the LHC operation. A main result is that woven carbon fiber cryosorber meets the LHC requirements and can be proposed as cryosorber for LHC. The summary results of these studies are presented. |
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| TPAP011 | Reliability Assessment of the LHC Machine Protection System | beam-losses, diagnostics, dumping, collider | 1257 | ||
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A large number of complex systems will be involved in ensuring a safe LHC operation, such as beam dumping and collimation, beam loss and position detection, quench protection, power interlock controller and beam interlock system. The latter will monitor the status of all other systems and trigger the beam abort if necessary. While the overall system is expected to provide an extremely high level of protection, none of the involved components should unduly impede machine operation by creating physically unfounded dump requests or beam inhibit signals. This paper investigates the resulting trade-off between safety and availability and provides quantitative results for the most critical protection elements.
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| TPAT026 | Synergia: An Advanced Object-Oriented Framework for Beam Dynamics Simultation | simulation, background, collective-effects, impedance | 1925 | ||
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Synergia is a 3-D, parallel, particle-in-cell beam dynamics simulation toolkit. At heart of the software development effort is the integration of two extant object-oriented accelerator modeling frameworks–Impact written in Fortran 90 and mxyptlk written in C++–so that they may be steered by a third, a more flexible human interface framework, written in Python. Recent efforts are focused on the refactoring of the Impact-Fortran 90 codes in order to expose more loosely-coupled interfaces to the Python interface framework.
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| TPAT098 | A Review of TeV Scale Lepton-Hadron and Photon-Hadron Colliders | collider, luminosity, lepton, linac | 4329 | ||
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Funding: Gazi University, Ankara, Turkey. |
The investigation of lepton-hadron and photon-hadron collisions at TeV scale is crucial both to clarify the strong interaction dynamics from nuclei to quark-parton level and for adequate interpretation of experimental data from future hadron colliders (LHC and VLHC). In this presentation different TeV scale lepton-hadron and photon-hadron collider proposals (such as THERA, "LEP"-LHC, QCD Explorer etc) are discussed. The advantages of linac-ring type colliders has been shown comparatively. |
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| TPPP054 | Studies of RF Breakdown of Metals in Dense Gases | resonance, collider, klystron, vacuum | 3259 | ||
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Funding: This work was supported in part by DOE STTR grant DE-FG02-02ER86145. |
A study of RF breakdown of metals in gases has begun as part of a program to develop RF cavities filled with dense hydrogen gas to be used for muon ionization cooling. A pressurized 800 MHz test cell has been used at Fermilab to compare the conditioning and breakdown behavior of copper, molybdenum, chromium, and beryllium electrodes as functions of hydrogen and helium gas density. These results are compared to the predicted or known RF breakdown behavior of these metals in vacuum. |
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| WPAE034 | Fast Neutron Damage Studies on NdFeB Materials | radiation, radioactivity, permanent-magnet, multipole | 2351 | ||
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Funding: Support of this work was under U.S. Dept. of Energy contracts DE-AC02-76SF00515, DE-AC02-76CH03000 and LCRD contract DE-FG02-03ER41280. |
Many materials and electronics need to be tested for the radiation environment expected at linear colliders (LC) where the accelerator and detectors will be subjected to large fluences of hadrons, leptons and gammas over the life of the facility. Although the linacs will be superconducting, there are still many potential uses for NdFeB in the damping rings, injection and extraction lines and final focus. Our understanding of the radiation damage situation for rare earth permanent magnet materials was presented at PAC2003 and our first measurements of fast neutron, stepped doses at the UC Davis McClellan Nuclear Reactor Center (UCD MNRC) were presented at EPAC2004 where the damage appeared proportional to the distances between the effective operating points and Hc. Here we have extended those doses and included more commercial samples together with the induced radioactivities associated with their respective dopants. Hall probe data for the external induction distributions are compared with vector magnetization measurements for the different materials. |
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| WPAE050 | First Calibrations of Alanine and Radio-Photo-Luminescence Dosemeters to a Hadronic Radiation Environment | proton, radiation, simulation, photon | 3097 | ||
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Alanine and Radio-Photo-Luminescence (RPL) dosimeters are used to monitor radiation doses occurring inside the tunnels of all CERN accelerators including the Large Hadron Collider (LHC). They are placed close to radiation sensitive machine components like cables or insulation of magnet coils to predict their remaining lifetime. The dosimeters are exposed to mixed high-energy radiation fields. However, up to now both dosimeter types are calibrated to 60Co-photons only. In order to study the response of RPL and alanine dosimeters to mixed particle fields like those occurring at CERN’s accelerators, an irradiation campaign at the CERN-EC High-Energy Reference field Facility (CERF-field) was performed. Moreover, the dosimeters were first time calibrated to a proton radiation field of a constant momentum of 24 GeV/c. In addition to the experiment FLUKA Monte Carlo simulations were carried out, which provide information concerning the energy deposition and the radiation field at the dosimeter locations.
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| ROAD001 | Recent Progress in Power Refrigeration Below 2 K for Superconducting Accelerators | collider, vacuum, SNS, superconductivity | 9 | ||
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As a result of technico-economical optimization and quest for increased performance, 2 K cryogenics is now present in large accelerator projects using superconducting magnets or acceleration cavities. Consequently, large cryogenic systems producing refrigeration capacity below 2 K in the kW range and with high efficiency over a large dynamic range are needed. After CEBAF and SNS, this is now the case for the Large Hadron Collider (LHC) project at CERN for which eight 2.4 kW @ 1.8 K refrigeration units are needed to cool each a 3.3 km long sector of high-field magnets. Combining cold hydrodynamic compressors in series with warm volumetric compressors, complete pre-series units as well as sets of series cold compressors have been intensively tested and validated from two different industrial suppliers. After recalling the possible 2 K refrigeration cycles and their comparative merits, this paper describes the specific features of the LHC system and presents the achieved performance with emphasis on the progress in terms of efficiency, operational compliance, reliability and maintenance. Perspectives of application to a future International Linear Collider based on cold RF technology are then briefly evoked.
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| RPPE001 | The CARE Accelerator R&D Programme in Europe | electron, proton, acceleration, linac | 749 | ||
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Funding: This work is supported by the European Community-Research Infrastructure Activity under the FP6 “Structuring the European Research Area” programme (CARE, contract number RII3-CT-2003-506395). |
CARE, an ambitious and coordinated programme of accelerator research and developments oriented towards HEP projects, has been launched in January 2004 by the main European laboratories and the European Commission within the 6th Framework Programme. This programme aims at improving existing infrastructures dedicated to future projects such as linear colliders, upgrades of hadron colliders and high intensity proton drivers. An important part of this programme is devoted to advancing the performance of the superconducting technology, both in the fields of RF cavities for electron and proton acceleration and of high field magnets, as well as to developing high intensity electron and proton injectors. We describe the R&D plans of the four main R&D activities and report on the results and progress obtained so far. |
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| RPPE018 | Material Damage Test with 450 GeV LHC-Type Beam | target, simulation, proton, injection | 1607 | ||
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The design of LHC protection elements is based on assumptions on damage levels, which are derived from simulations. A dedicated experiment was prepared and carried out to cross-check the validity of this approach by trying to damage material in a controlled way with beam. The impact of a 450 GeV beam extracted from the SPS on a specially designed high-Z target with a simple geometry, comprising several typical materials used for LHC equipment, was simulated. The beam intensities for the test were chosen to exceed the damage limits of parts of the target. Results of the simulations are presented and compared with test results.
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| RPPT072 | Ion Chamber Arrays for the NuMI Beam at Fermilab | target, ion, proton, focusing | 3892 | ||
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The NuMI beamline and the MINOS experiment will study at a long baseline the possible oscillation of muon neutrinos and provide a precision measurement of the oscillation parameters. Neutrinos are produced from charged pion decays, where the pions are produced from interaction of the 120 GeV FNAL Main Injector proton beam with a graphite target. Ion chamber arrays have been built to monitor the resulting muons from pion decays, as well as remnant hadrons at the end of the NuMI decay pipe. The arrays of ion chambers measure both the intensity and lateral profile of the muon and hadron beams, allowing studies of sytematics of the neutrino beam. We will describe the design, construction, and precise calibration of the ion chamber arrays. Initial data from commissioning of the beam line and experience from long-term operations will be presented.
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| ROPA007 | Vlasov Simulations of Beams and Halo | simulation, focusing, lattice, brightness | 581 | ||
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Even though PIC simulations have proven an efficient tool for beam simulations for many years, they are subject to numerical noise which only decreases slowly when the number of particles is increased. Therefore other methods might be preferable, when one is interested in accurate simulations of high intensity beams especially in the low density part of phase space. We have been developing new methods based on the direct resolution of the Vlasov equation on a grid of phase space. In order for these methods to be efficient special care needs to be taken to optimize the number of necessary grid points. We shall describe two different approaches that are used to this aim: moving grid methods and wavelet based automatic grid refinement. Beam simulations in different configurations using direct Vlasov methods will be presented.
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| FOAC004 | The Numi Neutrino Beam At Fermilab | target, proton, booster, antiproton | |||
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The Neutrinos at the Main Injector (NuMI) is a conventional neutrino beam facility which will use the intense 120 GeV proton beam from the Fermilab Main Injector accelerator. The facility is envisaged to service a variety experiments, in particular the already-constructed MINOS long baseline oscillation experiment, and the proposed NOvA experiment to observe muon neutrino to electron neutrino oscillations. Summarized will be the design of the primary and secondary beam focusing systems, instrumentation to validate the neutrino beam intensity, direction, and energy spectrum, and considerations for coping with the 0.4 MWatt MI beam. The beam line will be commissioned December, 2004, through February, 2005, whereupon operations may begin. Data from the commissioning and experience from first operations will be presented. Further, the suitability of the facility for accepting beam from a proposed 2MW proton driver is discussed.
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| FPAE008 | Iso-Adiabatic Merging of pbar Stacks in the Recycler | emittance, simulation, antiproton, collider | 1093 | ||
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Funding: Work supported by the Universities Research Association, Inc., under contract DE-AC02-76CH03000 with the U.S. Department of Energy. |
Here, I have proposed an efficient scheme to merge two stacks of pbars in the Recycler* with emittance dilution <15%. First I discuss a method to match energy spreads of the two stacks and subsequently merging them. The scheme is illustrated with multiparticle dynamics simulations and beam measurements in the Recycler. *G. Jackson, Fermilab-TM-1991, November, 1996. |
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