| Paper | Title | Other Keywords | Page |
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| TUYAA04 | Study to Mitigate Electron Cloud Effect in SuperKEKB | electron, MMI, simulation, solenoid | 95 |
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| During Phase-1 commissioning of the SuperKEKB from February to June 2016, electron cloud effects (ECE) were observed in the positron ring. The electron clouds were considered to exist in the beam pipes in the drift spaces of the ring, where the beam pipes have antechambers and titanium nitride (TiN) coating as countermeasures against ECE. Following this, permanent magnets and solenoids were attached to the beam pipes as additional countermeasures. Consequently, during Phase-2 commissioning from March to July 2018, experiments showed that the threshold beam current for exciting ECE increased by a factor of at least two relative to that during Phase-1 commissioning. While the countermeasures were strengthened, the effectiveness of the antechambers and TiN film coating was re-evaluated. From various simulations and experiments during Phase-2 commissioning, the antechamber was found to be less effective than expected with regard to reducing the number of photoelectrons in the beam channel. The TiN film coating, on the other hand, was considered to have a low secondary electron yield as expected. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUYAA04 | ||
| About • | paper received ※ 27 September 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019 | ||
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| TUPBB03 | Performance of the FCC-ee Polarimeter | electron, laser, polarization, scattering | 157 |
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| Inverse Compton scattering is the classical way to measure the electron beam polarization. Eligibility of the approach at high energy domain has been demonstrated by LEP, HERA and SLD experiments. Fast measurement of beam polarization allows to apply the resonant depolarization technique for precise beam energy determination. The distinctive feature of the FCC-ee polarimeter is the registration of scattered electrons along with scattered photons. Polarimeter is designed to measure the transverse polarization of the non-colliding pilot bunch with 1 % accuracy every second. Furthermore the same apparatus allows to measure the beam energy, longitudinal beam polarization (if any) and transverse beam positions/sizes at the place of installation. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUPBB03 | ||
| About • | paper received ※ 18 September 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019 | ||
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| WEXBA01 | IR Design for High Luminosity and Low Backgrounds | background, detector, luminosity, focusing | 194 |
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Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-76SF00515 and HEP New e+e− accelerator designs aim for factory-like performance with high-current beams and high luminosities. These new machines will push interaction region designs to new levels and require a careful evaluation of all previous background sources as well as introduce possibly new background sources. I present here a summary of standard background sources and also suggest a new possible background source for Synchrotron Radiation (SR) namely, specular reflection. In addition, one will have to pay closer attention to the beam tail particle distribution as this may become a significant source of SR background from the high-current and high-energy beams of these new designs. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-WEXBA01 | ||
| About • | paper received ※ 16 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019 | ||
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| WEXBA02 | Machine Detector Interface for the e+e− Future Circular Collider | detector, background, simulation, luminosity | 201 |
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| The international Future Circular Collider (FCC) study~[fccweb] aims at a design of p-p, \rm e+e-, e-p colliders to be built in a new 100~km tunnel in the Geneva region. The \rm e+e- collider (FCC-ee) has a centre of mass energy range between 90 (Z-pole) and 375~GeV (t\bar{t}). To reach such unprecedented energies and luminosities, the design of the interaction region is crucial. The crab-waist collision scheme~[ref:cw] has been chosen for the design and it will be compatible with all beam energies. In this paper we will describe the machine detector interface layout including the solenoid compensation scheme. We will describe how this layout fulfills all the requirements set by the parameters table and by the physical constraints. We will summarize the studies of the impact of the synchrotron radiation, the analysis of trapped modes and of the backgrounds induced by single beam and luminosity effects giving an estimate of the losses in the interaction region and in the detector. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-WEXBA02 | ||
| About • | paper received ※ 03 November 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019 | ||
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| WEXBA05 | Machine Detector Interface for CEPC | detector, solenoid, scattering, background | 217 |
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| The Circular Electron Positron Collider (CEPC) is a proposed Higgs factory with center of mass energy of 240 GeV to measure the properties of Higgs boson and test the standard model accurately. Machine Detector Interface (MDI) is the key research area in electron-positron colliders, especially in CEPC, it is one of the criteria to measure the accelerator and detector design performance. In this paper, we will introduce the CEPC superconducting magnets design, solenoid compensation, synchrotron radiation and mask design, detector background, collimator, mechanics assembly etc on, which are the most critical physics problem. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-WEXBA05 | ||
| About • | paper received ※ 29 September 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019 | ||
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| WEOAB01 | Commissioning Status of SuperKEKB Vacuum System | vacuum, MMI, wiggler, detector | 226 |
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| In the upgrade from the KEKB to the SuperKEKB, approximately 93% and 20% of the beam pipes and vacuum components of the positron ring and the electron ring were replaced with new ones. In the Phase-1 commissioning in 2016, vacuum scrubbing and confirmation of the stabilities of new vacuum components at approximately 1 A were carried out. Though some problems such as pressure bursts accompanying beam losses were revealed, no serious problem was found in the vacuum system. During the subsequent shutdown, the countermeasures against the problems were taken, and new beam pipes and components such as beam collimators were installed. The Phase-2 commissioning, where beam collision tuning was mainly performed, was carried out from March to July 2018. The collimators worked very well to suppress the background noise of the Belle-II detector, though some of them were damaged by the beam. The frequency of the pressure burst drastically decreased though the typical beam currents were lower than those of the Phase-1. The vacuum system of the SuperKEKB has been working generally well so far. The total beam doses of the SuperKEKB exceeded 1000 Ah, and the pressures decreased as expected. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-WEOAB01 | ||
| About • | paper received ※ 02 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019 | ||
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