| 1. |
- Olvegård, Maja, et al.
(författare)
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Overview Of The ESSnuSB Accumulator Ring
- 2016
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Ingår i: Proceedings of the 57<sup>th</sup> ICFA Advanced Beam Dynamics Workshop on High-Intensity, High Brightness and High Power Hadron Beams. ; , s. 105-109
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The European Spallation Source (ESS) is a research center based on the world's most powerful proton driver, 2.0 GeV, 5 MW on target, currently under construction in Lund. With an increased pulse frequency, the ESS linac could deliver additional beam pulses to a neutrino target, thus giving an excellent opportunity to produce a high-performance ESS neutrino Super-Beam (ESSnuSB). The focusing system surrounding the neutrino target requires short pulses. An accumulator ring and acceleration of an H- beam in the linac for charge-exchange injection into the accumulator could provide such short pulses. In this paper we present an overview of the work with optimizing the accumulator design and the challenges of injecting and storing 1.1E15 protons per pulse from the linac. In particular, particle tracking simulations with space charge will be described.
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| 2. |
- Autin, B., et al.
(författare)
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Automatic beam steering in the CERN PS complex
- 1995
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Ingår i: Proceedings of the 1995 16th Particle Accelerator Conference. - 0780329341 ; , s. 2178-2180
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Konferensbidrag (refereegranskat)abstract
- The recombination, transfer and injection of the four beams from the PS Booster to the PS Main Ring, have a high level of intricacy and are a subject of permanent concern for the operation of the PS Injector Complex. These tasks were thus selected as a test bench for the implementation of a prototype of an automatic beam steering system. The core of the system is based on a generic trajectory optimizer, robust enough to cope with imperfect observations. The algorithmic engine is connected to pick-up monitors and corrector magnets and its decision can be validated by the operator through a graphics user interface. Automatic beam steering can only be efficient if the beam optics is fully confirmed by experimental observations, a condition which forces the systematic elimination of errors both in hardware and software.
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| 3. |
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| 4. |
- Cederkall, Joakim, et al.
(författare)
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The ESSνSB project
- 2020
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Ingår i: European Physical Society Conference on High Energy Physics, EPS-HEP2019. - Trieste, Italy : Sissa Medialab srl. ; EPS-HEP2019
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Konferensbidrag (refereegranskat)abstract
- The ESS nu SB project aims to produce a neutrino beam of unique intensity for a long-baseline oscillation measurement of CP-violation in the leptonic sector. The project, supported within the H2020 framework programme of the European Union, is currently in a conceptual design study phase, and work is ongoing within the project to develop viable solutions for the upgrade of the linear accelerator of the European Spallation Source (ESS), for the associated ring accumulator and the high-power target stations, as well as to establish solutions for the near and far detectors. The unique strength of the project lies in the capability to produce a neutrino beam that is intense enough to place the far detector at the second oscillation maximum. Such a placement will reduce the sensitivity of the experiment to systematic errors, which, due to the recently established value of the neutrino mixing angle theta(13), is now known to limit the measurement precision at the first oscillation maximum. In this paper we outline the basic components of the project and discuss the status of the ongoing conceptual design study.
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| 5. |
- Hoa, C., et al.
(författare)
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Parametric study of heat deposition from collision debris into the insertion superconducting magnets for the LHC luminosity upgrade
- 2007
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Ingår i: IEEE Particle Accelerator Conference, PAC07. - 9781424409167 ; , s. 323-325
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Konferensbidrag (refereegranskat)abstract
- With a new geometry in a higher luminosity environment, the power deposition in the superconducting magnets becomes a critical aspect to analyze and to integrate in the insertion design. In this paper, we quantify the power deposited in magnets insertion at variable positions from the interaction point (IP). A fine characterization of the debris due to the proton-proton collisions at 7 TeV, shows that the energetic particles in the very forward direction give rise to non intuitive dependences of the impacting energy on the magnet front face and inner surface. The power deposition does not vary significantly with the distance to the interaction point, because of counterbalancing effects of different contributions to power deposition. We have found out that peak power density in the magnet insertion does not vary significantly with or without the Target Absorber Secondaries (TAS) protection.
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| 6. |
- Jones, F. W., et al.
(författare)
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Simulation of decays and secondary ion losses in a betabeam decay ring
- 2007
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Ingår i: IEEE Particle Accelerator Conference, PAC07. - 9781424409167 ; , s. 3232-3234
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Konferensbidrag (refereegranskat)abstract
- Radioactive ions injected into the decay ring of a Betabeam neutrino facility will constitute a continuous source of decay products distributed around the ring. Secondary ions from beta decays will differ in charge state from the primary ions and will follow widely off-momentum orbits. In the racetrack configuration of the ring, they will be mismatched in the long straights and may acquire large amplitudes, but the great majority of losses will be in the arcs. We describe here a comprehensive model of ion decay, secondary ion tracking, and loss detection, which has been implemented in the tracking and simulation code Accsim. Methods have been developed to accurately follow ion trajectories at large momentum deviations as well as to detect their impact coordinates on vacuum chamber walls and possibly inside magnetic elements. Using secondary-ion data from Accsim and post-processing with Mathematica, we have implemented a follow-on simulation in FLUKA with a 3D geometry of decay ring components and physics models for ion interactions in matter, allowing radiological studies and in particular the visualization and analysis of heat deposition in the dipole magnets which is a critical design factor for the ring. In our simulations we have also implemented absorber elements which are intended to localize the majority of losses outside of the dipoles. These studies provide estimates of ring performance (in terms of loss concentration and management), the effectiveness of absorbers, and the implications for successful superconducting dipole operation.
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| 7. |
- Wildner, Elena, et al.
(författare)
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A large aperture superconducting dipole for beta beams to minimize heat deposition in the coil
- 2007
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Ingår i: IEEE Particle Accelerator Conference, PAC07. - 9781424409167 ; , s. 365-367
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Konferensbidrag (refereegranskat)abstract
- The aim of beta beams in a decay ring is to produce highly energetic pure electron neutrino and anti-neutrino beams coming from b-decay of 18Ne10+ and 6He2+ ion beams. The decay products, having different magnetic rigidities than the main ion beam, are deviated inside the dipole. The aperture and the length of the magnet have to be optimized to avoid that the decay products hit the coil. The decay products are intercepted by absorber blocks inside the beam pipe between the dipoles to protect the following dipole. A first design of a 6T arc dipole using a cosine theta layout of the coil with an aperture of 80 mm fulfils the optics requirements. Heat deposition in the coil has been calculated using different absorber materials to find a solution to efficiently protect the coil. Aspects of impedance minimization for the case of having the absorbers inside the beam pipe have also been addressed.
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| 8. |
- Wildner, Elena
(författare)
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Accelerators for Physics Experiments : From Diagnostics and Control to Design
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis develops techniques of control-methods, optimization, and diagnostics of accelerator equipment and the produced particle beams with emphasis on the Large Hadron Collider (LHC) project at CERN. From a solid knowledge of the characteristics of the manufactured accelerator equipment gained from in-depth measurements and analysis of measured data, a link to an enhanced equipment design can be made. These techniques will be demonstrated in applications related to the LHC magnet production and to the LHC upgrade studies. The LHC is a 27 km long superconducting accelerator, which CERN, the European high-energy particle physics research organisation, is presently being commissioned in a tunnel 80 m under ground level in the Geneva region. This machine forms the last link in an interconnected chain of several particle accelerators at CERN. The overall system performance, i.e. the quality of particle beams being accelerated in this accelerator chain is directly related to the control of the quality of the superconducting magnets used in the last link, in the LHC. Different upgrade scenarios to reach the ultimate design luminosity and beyond that, implying major machine changes are presently being studied. These scenarios all pose very challenging design requirements for magnets situated in the beam collision regions where extremely radioactive environments have to be dealt with. The LHC is expected to produce very highly energetic and intense particle beams for a number of physics experiments during the next decades, making the subjects of the thesis both timely and important. The work described has been performed at CERN, which has become the largest high-energy physics laboratory in the world. Here, a number of particle accelerators are connected in series to permit the acceleration of particles to unprecedented high energies to explore the nature of our universe. The accelerators at CERN are assembled of a large number of parts requiring a high level of technological know-how. Control systems and optimization procedures play a natural and necessary role to fulfil the requirements. Diagnostics and control system technology have been used to increase the efficiency of accelerator operation. An extensive analysis of the measured magnetic field have been used to optimize the delicate process of controlling the assembly of superconducting accelerator magnets for the LHC. This paper also describes the control procedures developed, to permit the adjustment of the geometric shape of the 15 m long dipole to optimize the field quality and beam aperture. From a detailed statistical analysis of the collected geometry data from the 1232 LHC main dipole magnets unresolved issues concerning the measurements were explained and corrected, providing more accurate information for the alignment of the main dipoles and quadrupoles. The LHC will start operation in 2008, after a most careful installation of all magnets and a huge volume of other equipment in the accelerator tunnel. In particular, the very specialized welding techniques and the brazing of tubes, bellows and conductors, have posed great challenges. Tenths of thousands of welds that have to withstand temperature changes of 300 K and operation with super-fluid helium at 1.9 K have been made. The magnet systems that create the conditions for particle collisions in the two main experiments, the insertion triplets, will have to be exchanged when upgrading the performance of the machine. The upgrade of the machine’s luminosity is expected after 4 years of LHC operation at nominal luminosity. Unless the new magnets are very carefully designed and well shielded the particle debris from the increased collision rates will perturb their operation. Using a new superconductor technology, limiting the probability of magnet quenches, combined with a new layout of the insertion region can minimize the effect of the impinging debris. The necessary shielding layout to protect the magnet coils will be discussed. The future of accelerators for particle physics is important: the development of accelerator technology to produce neutrino beams from beta decaying ions is one possibility for new physics. This subject will be treated from the aspect of energy deposition from decay products in superconducting magnet coils.
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| 9. |
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| 10. |
- Wildner, Elena, et al.
(författare)
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Control of the Dipole Cold Mass Geometry at CERN to Optimize LHC Performance
- 2006
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Ingår i: IEEE transactions on applied superconductivity (Print). - 1051-8223 .- 1558-2515. ; 16:2, s. 212-215
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Tidskriftsartikel (refereegranskat)abstract
- The detailed shape of the 15 m long superconducting LHC dipole cold mass is of high importance as it determines three key parameters: the beam aperture, nominally of the order of 10 beam standard deviations; the connectivity of the beam- and technical lines between magnets; the transverse position of nonlinear correctors mounted on the dipole ends. An offset of the latter produces unwanted beam dynamics perturbations. The tolerances are in the order of mm over the length of the magnet. The natural flexibility of the dipole and its mechanical structure allow deformations during handling and transportation which exceed the tolerances. This paper presents the observed deformations of the geometry during handling and various operations at CERN, deformations which are interpreted thanks to a simple mechanical model. These observations have led to a strategy of dipole geometry control at CERN, based on adjustment of the position of its central support (the dipole is supported at three positions, horizontally and vertically) to recover individually or statistically their original shape as manufactured. The implementation of this strategy is discussed, with the goal of finding a compromise between conflicting requirements: quality of the dipole geometry, available resources for corrective actions and magnet installation strategy whereby the geometry tolerances depend on the final magnet position in the machine.
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