| Paper | Title | Page |
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| MOPGW081 | Measurements of Stray Magnetic Fields at CERN for CLIC | 289 |
| SUSPFO099 | use link to see paper's listing under its alternate paper code | |
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| Simulations have shown that the Compact Linear Collider (CLIC) is sensitive to external dynamic magnetic fields (stray fields) to the nT level. Magnetic fields are not typically measured to this precision at CERN. Past measurements of the background magnetic field at CERN are limited. In this paper new measurements are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW081 | |
| About • | paper received ※ 01 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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| MOPGW082 | Mitigation of Stray Magnetic Field Effects in CLIC with Passive Shielding | 293 |
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| Simulations have shown the Compact Linear Collider (CLIC) is sensitive to external dynamic magnetic fields (stray fields) to the nT level. Due to these extremely tight tolerances, mitigation techniques will be required to prevent performance loss. A passive shielding technique is envisaged as a potential solution. A model for passive shielding is presented along with calculations of its transfer function. Measurements of the transfer function of a promising material (mu-metal) that can be used for passive shielding are presented. The validity of passive shielding models in small amplitude magnetic fields is also discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW082 | |
| About • | paper received ※ 01 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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| MOPMP016 | Intra-Bunch Energy Spread Minimisation for CLIC Operation at a Centre-of-Mass Energy of 350 GeV | 458 |
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| The first stage of the electron-positron Compact Linear Collider (CLIC) is designed with a centre-of-mass energy of 380 GeV. A dedicated threshold scan in the vicinity of 350 GeV is envisioned with a total integrated luminosity of 100 fb-1. This scan calls for a very small intra-bunch energy spread in order to achieve an excellent collision energy resolution. This paper presents an optimised assignment of RF accelerating gradients and phases in the CLIC main linac for operation at 350 GeV, which minimises the energy spread at the end of the main linac whilst preserving a small emittance growth. Variation of the bunch length and charge is studied in order to further reduce the energy spread; the effect on both the peak and total luminosity is discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP016 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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| MOPMP017 | Beam Orbit Correction in the CLIC Main Linac Using a Small Subset of Correctors | 461 |
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Beam orbit correction in future linear colliders, such as the Compact Linear Collider (CLIC), is essential to mitigate the effect of accelerator element misalignment due to ground motion. The correction is performed using correctors distributed along the accelerator, based on the beam position monitor (BPM) readout from the preceding bunch train, with a train repetition frequency of 50 Hz. This paper presents the use of the MICADO algorithm* to select a subset of N ~ 10 correctors (from a total of 576) to be used for orbit correction in the designed 380 GeV centre-of-mass energy first-stage of CLIC. The optimisation of the number N of correctors, the algorithm’s gain and the corrector step size is described, and the impact of a number of BPMs and correctors becoming unavailable is addressed. The application of a MICADO algorithm to perform dispersion free steering, by reducing the beam orbit difference between two beams with different energies, is discussed.
* B. Autin & Y. Marti, "Closed orbit correction of A.G. machines using a small number of magnets", CERN-ISR-MA/73-17, 1973. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP017 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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| MOPMP018 | Beam-Based Beamline Element Alignment for the Main Linac of the 380 GeV Stage of CLIC | 465 |
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| The extremely small vertical beam size required at the interaction point of future linear colliders, such as the Compact Linear Collider (CLIC), calls for a very small vertical emittance. The strong wakefields in the high frequency 12 GHz CLIC accelerating structures set tight tolerances on the alignment of the main linac’s beamline elements and on the correction of the beam orbit through them in order to mantain a small emittance growth. This paper presents the emittance growth due to each type of beamline element misalignment in the designed 380 GeV centre-of-mass energy first-stage of CLIC, and the emittance growth following a series of beam-based alignment (BBA) procedures. The BBA techniques used are one-to-one steering, followed by dispersion free steering and finally accelerating structure alignment using wakefield monitors. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP018 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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