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| MOPPC013 | Optics and Lattice Optimizations for the LHC Upgrade Project | 151 |
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| The luminosity upgrade of the LHC collider at CERN is based on a strong focusing scheme to reach lowest values of the beta function at the collision points. Several issues have to be addressed in this context, that are considered as mid term goals for the optimisation of the lattice and beam optics: Firstly a number of beam optics have been developed to establish a baseline for the hardware R&D, and to define the specifications for the new magnets that will be needed, in Nb3Sn and in NbTi technology. Secondly, the need for sufficient flexibility of the beam optics especially for smallest β* values has to be investigated as well as the need for a smooth transition between the injection and the collision optics. Finally the performance of the optics based on flat and round beams has to be compared and different ways have to be studied to optimise the chromatic correction, including the study of local correction schemes. This paper presents the status of this work, which is a result of an international collaboration, and summarises the main parameters that are foreseen to reach the HL-LHC luminosity goal. | ||
| MOPPD077 | Studies for an Alternative LHC Non-Linear Collimation System | 544 |
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Funding: This work has been carried out through of the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program. A LHC nonlinear Betatron cleaning collimation system would allow larger gap for the mechanical jaws, reducing as a consequence the collimator-induced impedance, which may limit the LHC beam intensity. In this paper, the performance of the proposed system is analyzed in terms of beam losses distribution around the LHC ring and cleaning efficiency in stable physics condition at 7TeV for Beam1. Moreover, the energy deposition distribution on the machine elements is compared to the present LHC Betatron cleaning collimation system in the Point 7 Insertion Region (IR). |
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| MOPPD078 | Accelerator Physics Study on the Effects from an Asynchronous Beam Dump in the LHC Experimental Region Collimators | 547 |
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Funding: This work has been carried out through of the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program. Asynchronous beam aborts at the LHC are to be expected once per year. Accelerator physics studies of asynchronous dumps have been performed at different beam energies and beta-stars. The loss patterns are analyzed in order to identify the losses in particular on the Phase 1 Tertiary Collimators (TCT), since their Tungsten jaw insert has a low damage threshold with respect to the loss load expected. Settings for the tilt angle of the TCTs are discussed with the aim of reducing the thermal loads on the TCT themselves. |
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| MOPPD080 | Improved Robustness of the LHC Collimation System by Operating with a Jaw-beam Angle | 553 |
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Funding: This work has been carried out through of the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program. The robustness of the Phase I collimation system could be improved playing with the angular orientation of each single jaw. A preliminary study on the asymmetric misalignment of the collimator jaws, scanning through different jaw angles and varying beam sizes and energy, have been carried out, aiming at minimizing the energy deposited on metallic collimators, following an asynchronous dump. |
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| MOPPR042 | Characterization Tests of a Stripline Beam Position Monitor for the CLIC Drive Beam | 873 |
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Funding: FPA2010-21456-C02-01, SEIC-2010-00028 A prototype of a stripline Beam Position Monitor (BPM) with its associated readout electronics has been developed at CERN in collaboration with SLAC, LAPP and IFIC. In this paper, the design and simulations of the BPM with the analog readout chain and the BPM test bench are described, and the results of the first characterization tests are presented. The position resolution and accuracy parameters are expected to be below 2μm and 20μm respectively for a beam with a bunching frequency of 12GHz, an average current of 101A and a machine repetition rate of 50Hz. |
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| MOPPR043 | Design, Construction and Calibration of a First Prototype of Beam Position System for Hadron Therapy Facilities | 876 |
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Funding: AIC10-D-000518 and AIC-D-2011-0673. Beam Position Monitors (BPM) are essential elements in the instrumentation for the beam control in hadron therapy accelerators. The measurement of the beam position become more important at the secondary transport lines towards the patient room where this parameter must be completely determined. In this paper we describe the design, construction, read-out electronics and first calibration tests of a new type of BPM based on four scintillating fibers coupled to four photodiodes to detect the light produced by the fibers when intercepting the beam tails. The prototype will serve to evaluate the different design options in the mechanical and the read-out electronics implementation as well as to define the best processing method to get the beam position. |
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| MOPPR044 | Optics and Emittance Studies using the ATF2 Multi-OTR System | 879 |
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Funding: Funding Agency: FPA2010-21456-C02-01. Work supported in part by Department of Energy Contract DE-AC02-76SF00515. A multi-OTR system (4 beam ellipse diagnostic devices based on optical transition radiation) was installed in the extraction line of ATF2 and has been fully operational since September 2011. The OTRs have been upgraded with a motorized zoom-control lens system to improve beam finding and accommodate different beam sizes. The system is being used routinely for beam size and emittance measurements as well as coupling correction. In this paper we present measurements performed during the winter run of 2011 and the early 2012 runs. We show the reconstruction of twiss parameters and emittance, discuss the reliability of the OTR system and show comparisons with simulations. We also present new work to calculate all 4 coupling terms and form the “4-D” intrinsic emittance of the beam utilizing all the information available from the 2-D beam profile images. We also show details and experimental results for performing a 1-shot automated coupling correction. |
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| TUPPR016 | Final Cross Section Design of the Stripline Kicker for the CLIC Damping Rings | 1843 |
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Funding: IDC-20101074 and FPA2010-21456-C02-01 The CLIC design relies on the presence of Pre-Damping Rings (PDR) and Damping Rings (DR) to achieve, through synchrotron radiation, the very low emittance needed to fulfill the luminosity requirements. Kicker systems are required to inject and extract the beam from the Pre-Damping and Damping Rings. In order to achieve low beam coupling impedance and reasonable broadband impedance matching to the electrical circuit, striplines have been chosen for the kicker elements. In this paper the final design for the DR kicker is presented, including an optimization of the geometric parameters to achieve the requirements for both characteristic impedance and field homogeneity. In addition, a sensitivity analysis of characteristic impedance and field homogeneity to geometric parameters is reported. |
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| TUPPR017 | Nonlinear Post-Linac Energy Collimation System for the Compact Linear Collider | 1846 |
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Funding: FPA2010-21456-C02-01 The post-linac energy collimation system of the Compact Linear Collider (CLIC) has been designed to provide protection of the Beam Delivery System (BDS) against off-energy and mis-steered beams. The conventional baseline design consists of a two stage spoiler-absorber scheme. The CLIC energy collimators are required to withstand the impact of a full bunch train. This condition makes the energy collimator design very challenging, since the collimators have to deal with a total beam power of 14 MW at nominal energy and intensity. The increase of the transverse spot size at the collimators using nonlinear magnets could be a potential solution to guarantee the survivability of the collimators. In this paper we present an alternative nonlinear optics design for the CLIC energy collimation system. Possibilities for its optimization are discussed in view of performance simulation results. |
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| TUPPR018 | Beam Impedance Study of the Stripline Kicker for the CLIC Damping Ring | 1849 |
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Funding: FPA2010-21456-C02-01 CLIC Pre-Damping (PDR) and Damping Rings (DR) are required for reducing the emittance of the electron and positron beams before being accelerated in the main linac. Several stripline kicker systems are used to inject and extract the beam from the PDR and DR. Wakefields produced by the charged particles when passing through the aperture of the stripline kickers may become an important source of emittance growth; for this reason, simulations of longitudinal and transverse beam impedance in the frequency domain, and their equivalent in the time domain are needed. First analytical approaches, future simulations and tests planned are presented in this paper. |
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| TUPPC086 | Conceptual Design of the CLIC damping rings | 1368 |
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| The CLIC damping rings are designed to produce unprecedentedly low-emittances of 500 nm and 5 nm normalized at 2.86 GeV, in all beam dimensions with high bunch charge, necessary for the performance of the collider. The large beam brightness triggers a number of beam dynamics and technical challenges. Ring parameters such as energy, circumference, lattice, momentum compaction, bending and super-conducting wiggler fields are carefully chosen in order to provide the target emittances under the influence of intrabeam scattering but also reduce the impact of collective effects such as space-charge and coherent synchrotron radiation. Mitigation techniques for two stream instabilities have been identified and tested. The low vertical emittance is achieved by modern orbit and coupling correction techniques. Design considerations and plans for technical system, such as damping wigglers, transfer systems, vacuum, RF cavities, instrumentation and feedback are finally reviewed. | ||