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| MOPMB020 | Transverse Intensity Distribution Measurement of Ion Beams Using Gafchromic Films | ion, radiation, cyclotron, tandem-accelerator | 130 |
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| A possible method of measuring the transverse spatial distribution of energetic ion beams is developed at Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology (formerly, Japan Atomic Energy Agency). For this purpose, a radiochromic film, Gafchromic film (Ashland Inc.), is employed since it enables us to easily measure a large-area irradiation field distribution at a high spatial resolution. Gafchromic EBT3 and HD-V2 films are irradiated with ion beams of various species and kinetic energies extracted from a cyclotron and electrostatic accelerators at QST/Takasaki. Then, the coloration response of the films is analyzed in terms of the optical density. It is demonstrated that EBT3 and HD-V2 films are useful for the beam profile measurement at low fluence and at low energy, respectively. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB020 | ||
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| MOPMR022 | Beam-based Alignment of CLIC Accelerating Structures Utilizing Their Octupole Component | emittance, collider, linear-collider, linac | 280 |
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| Alignment of the accelerating structures is essential for emittance preservation in long linear accelerators such as the Compact Linear Collider (CLIC). The prototype structures for CLIC have four radial waveguides connected to each cell for damping wakefields and this four-fold symmetry is responsible for an octupole component of the radio-frequency fields, phase-shifted 90 degrees with respect to the accelerating mode. The octupole field causes a nonlinear dependence of the transverse beam deflection with respect to the position within the accelerating structure. By transversely moving the beam with two upstream steering magnets, and observing the deflection with beam position monitors or screens, the electromagnetic center of the structure can be found. We discuss the applicability of this method for aligning the beam in the accelerating structures. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR022 | ||
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| MOPOR009 | The HL-LHC Impedance Model and Aspects of Beam Stability | impedance, HOM, cavity, focusing | 606 |
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Funding: Research supported by the High Luminosity LHC project The LHC upgrade to the HLLHC foresees new challenging operational scenarios from the beam dynamics point of view. In order to ensure good machine operation and performance, the machine impedance, among other possible sources of instabilities like beam-beam and electron cloud, needs to be carefully quantified profiting also from the current LHC operation. In this work we present the HLLHC impedance model mainly focusing on the contribution of low-impedance collimators and crab cavities: the first reduces the broad-band impedance baseline thanks to the higher jaw material conductivity, the second increases the machine luminosity at the price of increasing the coupled bunch stabilizing octupole current threshold. Other elements like the injection protection absorber (TDI) will be also discussed. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR009 | ||
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| MOPOR022 | Beam Dynamics Observations of the 2015 High Intensity Scrubbing Runs at the Cern Sps | electron, operation, injection, emittance | 648 |
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| Beam quality degradation caused by e-cloud effects has been identified as one of the main performance limitations for high intensity LHC beams with 25 ns bunch spacing in the SPS. In view of the beam parameters targeted with the LHC injectors upgrade (LIU) project, about two weeks of SPS machine time in 2015 were devoted to dedicated scrubbing runs with high intensity LHC 25 ns and dedicated 'doublet' beams in order to study the achievable reduction of e-cloud effects and quantify the consequent beam performance improvements. This paper describes the main observations concerning the coherent instabilities and beam dynamics limitations encountered as well as a detailed characterisation of the performance reach with the highest beam intensity presently available from the pre-injectors. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR022 | ||
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| MOPOY040 | Design of the 100 MeV Proton Beam Line for Low Flux Application | target, vacuum, beam-transport, proton | 938 |
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Funding: This work was supported by the Ministry of Science, ICT & Future Planning of the Korean Government. KOMAC has been operating two beam lines for user service since 2013. A new beam line was completed in 2015 for radioisotope production and has a plan to be commissioned in 2016. Another beam line was proposed to supply low flux beam to users. The maximum energy and average current are 100 MeV and 10 nA. The beam line consists of collimator, energy degrader, dipole magnet for energy separation and octupole magnet for uniform beam production. In this paper, the design of the beam line and its components is presented. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY040 | ||
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| TUPMB001 | Magnets for the ESRF-EBS Project | quadrupole, dipole, permanent-magnet, sextupole | 1096 |
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| A major upgrade project known as ESRF-EBS, Extremely Brilliant Source is planned at the European Synchrotron Radiation Facility (ESRF) in the coming years. A new storage ring will be built, aiming to decrease the horizontal emittance and to improve the brilliance and coherence of the X-ray beams. The lattice of the new storage ring relies on magnets with demanding specifications: dipoles with longitudinal gradient (field ranging from 0.17 T up to 0.67 T), strong quadrupoles (up to 90 T/m), combined function dipole-quadrupoles with high gradient (0.57 T and 37 T/m), strong sextupoles and octupoles. The design of these magnets is based on innovative solutions; in particular, the longitudinal gradient dipoles are permanent magnets and the combined dipole-quadrupoles are single-sided devices. The design of the magnets is finished and prototypes of innovative magnets have been built. The procurement of the magnets has started. Call for Tenders have been sent to a pre-qualified short list of magnet manufacturers. The longitudinal gradient dipoles will be assembled and measured in house. The design of the magnets, the prototype results and procurement status will be presented. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB001 | ||
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| TUPMB023 | MAX IV 3 GeV Storage Ring Magnet Block Production Series Measurement Results | storage-ring, dipole, lattice, synchrotron | 1157 |
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| The MAX IV 3 GeV storage ring magnets are integrated "magnet block" units consisting of several consecutive magnet elements precision-machined out of a common solid iron block. In the 3 GeV ring, there are 140 magnet blocks containing a total of 1320 magnet elements. During the manufacturing phase of the project, a field measurement was performed for each magnet element, by Hall probe and/or by rotating coil. This article presents an overview of the magnetic field measurement results that were obtained for the full production series. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB023 | ||
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| TUPMB037 | Instruments and Methods for the Magnetic Measurement of the Super-FRS Magnets | dipole, quadrupole, sextupole, cryogenics | 1183 |
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| The Super-FRS is a new fragment separator to be built as part of the Facility for Antiproton and Ion Research (FAIR) [\ref{fairweb}] at Darmstadt. The acceptance tests and magnetic measurements of the superferric separation dipoles and multiplets (containing quadrupole and higher-order magnets) will be performed at CERN in collaboration with GSI/FAIR [\ref{abstractfacility}]. This paper presents the methods and challenges of the magnetic field measurements, and the required instruments for measuring the transfer function, field quality, and magnetic axis. A prototype for each system has been produced in order to validate the measurement methods, the instruments, and the mechanical integration. In this paper will present the design and production of the prototypes, the design of the instruments for the series measurements, and the results of the metrological characterization. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB037 | ||
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| TUPMB041 | The SuperKEKB Interaction Region Corrector Magnets | quadrupole, sextupole, optics, luminosity | 1193 |
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| Work for the SuperKEKB luminosity upgrade of the KEKB asymmetric e+e− collider is near completion. In this paper we review the design, production and testing of superconducting correction coils, that are needed to achieve the desired IR optics performance, and are integrated with the final focus magnets. For SuperKEKB 43 coils were produced at BNL using Direct Wind techniques. These coils underwent preliminary warm field harmonic quality assurance measurements before shipment to KEK. At KEK final cold measurements of these coils were made prior to their ultimate integration with the SuperKEKB IR magnets. SuperKEKB corrector production was challenging due to the large number of coil types and configurations that had to be fitted into very limited available space. Also the nature of the SuperKEKB optics sets fairly stringent local field quality requirements for these coils. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB041 | ||
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| TUPMW011 | Current Status of Instability Threshold Measurements in the LHC at 6.5 TeV | damping, impedance, simulation, electron | 1434 |
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| Throughout 2015, many measurements of the minimum stabilizing octupole current required to prevent coherent transverse instabilities have been performed. These measurements allow the LHC impedance model at flat top to be verified and give good indicators of future performance and limitations. The results are summarized here, and compared to predictions from the simulation code DELPHI. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW011 | ||
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| TUPMW026 | Feed-Forward Corrections for Tune and Chromaticity Injection Decay During 2015 LHC Operation | injection, operation, hadron, collider | 1489 |
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| After two years of shutdown, the Large Hadron Collider (LHC) has been operated in 2015 at 6.5 TeV, close to its designed energy. When the current is stable at low field, the harmonic components of the main circuits are subject to a dynamic variation induced by current redistribution on the superconducting cables. The Field Description of the LHC (FiDel) foresaw an increase of the decay at injection of tune (quadrupolar components) and chromaticity (sextupolar components) of about 50% with respect to LHC Run1 due to the higher operational current. This paper discusses the beam-based measurements of the decay during the injection plateau and the implementation and accuracy of the feed-forward corrections as present in 2015. Moreover, the observed tune shift proportional to the circulating beam intensity and it's foreseen feed-forward correction are covered. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW026 | ||
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| TUPOR030 | Design of Octupole Channel for Integrable Optics Test Accelerator | optics, simulation, dynamic-aperture, electron | 1731 |
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| We present the design of octupole channel for Integrable Optics Test Accelerator (IOTA). IOTA is a test accelerator at Fermilab, aimed to conduct research towards high-intensity machines. One of the goals of the project is to demonstrate high nonlinear betatron tune shifts while retaining large dynamic aperture in a realistic accelerator design. At the first stage the tune shift will be attained with a special channel of octupoles, which creates a variable octupole potential over a 1.8 m length. The channel consists of 18 identical air-cooled octupole magnets. The magnets feature a simple low-cost design, while meeting the requirements on maximum gradient - up to 1.4 kG/cm3, and field quality - strength of harmonics below 1%. Numerical simulations show that the channel is capable of producing a nonlinear tune shift of 0.08 without restriction of dynamic aperture of the ring. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR030 | ||
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| WEPOY030 | First BTF Measurements at the Large Hadron Collider | injection, betatron, damping, simulation | 3051 |
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| During the Run I in 2012, several instabilities have been observed at the Large Hadron Collider (LHC) during the Betatron squeeze. The predictions of instability thresholds are based on the computation of the beam Landau damping by calculating the Stability Diagrams (SD). These instabilities could be explained by a deterioration of the SD due to beam-beam resonance excitation which could change the particle distributions. Beam Transfer Functions (BTF) provide a measurement of the Stability Diagram. The BTFs are sensitive to the particle detuning with amplitude as well as to the particle distributions therefore they represent a powerful tool to understand experimentally the stability of beams during the LHC operational cycle. First BTF measurements at the LHC are presented for different machine configurations and settings and compared to predictions. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY030 | ||
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| THPMR032 | Dynamical Aperture Control in Accelerator Lattices With Multipole Potentials | controls, multipole, lattice, resonance | 3455 |
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| We apply two analytical methods to control accelerator dynamic aperture (DA) with multipole potentials. Both methods assume that accelerator model can be represented as a product of unperturbed and perturbed exponential operators with exponent of perturbed operator given as formal power series in perturbation parameter and known dependence of series coefficients on lattice parameters such as multipole strength distribution. Normal form method can be applied to the above representation and then lattice parameters are used to control normal form Hamiltonian coefficients. Hamiltonian control can be used to compute control term and lattice parameters are then fitted to approximate corresponding controlled operator. Theoretical results as well as model examples are presented. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR032 | ||
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| THPMR036 | Improved Methods for the Measurement and Simulation of the CERN SPS Non-linear Optics | optics, sextupole, multipole, impedance | 3464 |
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| Good knowledge of the non-linear properties of the SPS lattice is crucial for modelling and optimising the machine performance in the presence of collective effects leading to incoherent tune spreads such as space charge, e-cloud and beam coupling impedance. In view of the LHC injectors upgrade (LIU) project and the future SPS operation in a regime dominated by such collective effects, detailed measurements of the SPS non-linear chromaticity and detuning with amplitude have been performed for the two optics configurations presently available for LHC type beams. The measurement results are used to fit systematic multipole components to the main magnets of the SPS MADX model as a basis for the non-linear machine model that can be used for beam dynamics simulations. The implications for the operation of the SPS with the LIU beam parameters are discussed. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR036 | ||
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| THPMR039 | Commissioning of Non-linear Optics in the LHC at Injection Energy | injection, dipole, optics, operation | 3476 |
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| Commissioning of the nonlinear optics at injection in the LHC was carried out for the first time in 2015 via beam-based methods. Building upon studies performed during Run I, corrections to the nonlinear chromaticity and detuning with amplitude were obtained. These corrections were observed to reduce beam-loss during measurement of linear optics. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR039 | ||
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| THPOR004 | Magnetic Measurement for Superconducting-Quadrupole-Magnets of Final-Focus System for SuperKEKB | quadrupole, sextupole, luminosity, radiation | 3771 |
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| SuperKEKB is an upgrade project of KEKB to increase its luminosity to 8 x 1035 cm-2 s-1 based on the nano-beam scheme. In SuperKEKB, one of a key element is a final-focus system; it reduces e−/e+ beam size to 50 nm in vertical and 10 μm in horizontal direction at an interaction point (IP). The system consists of eight superconducting quadrupole magnets and four quadrupoles are aligned on the each beam line. The quadrupole, QC1P(QC1E), which is located at the closest position to the IP on the e+(e−) beam line, generates a field gradient of about 70 T/m. An inner diameter of coil and a magnetic length for QC1P(QC1E) are 25(33) mm and 334(373) mm, respectively. The production of all quadrupole magnets are completed. To confirm their field qualities, we performed magnetic measurement for each magnet in advance to be integrated into cryostats on the beam lines. In the measurement, the quadrupoles were cooled down to 4.2 K in a test vertical cryostat and field harmonic components were measured with harmonic coils. The magnitude of error multipole components for all magnets met requirements from beam optics design. In this paper we describe the measurement results. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR004 | ||
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