Conveners
FCC-ee accelerator: Parameters and optics (review)
- Eliana Gianfelice-Wendt (Fermi National Accelerator Lab. (US))
FCC-ee accelerator: Machine detector interface (review)
- Jie Gao (Institute of High Energy Physics, China)
FCC-ee accelerator: Collective effects and top-up (review)
- Evgeni Levitchev (Unknown)
FCC-ee accelerator: CEPC and others
- Katsunobu Oide (High Energy Accelerator Research Organization (JP))
FCC-ee accelerator: FCC-ee energy calibration & polarization (review)
- Alain Blondel (Universite de Geneve (CH))
The 100 km FCC-ee e+/e- circular collider requires luminosities in the order of 10^35 cm^-2 s^-1 and very low emittances of 1nm for eps_x and 2pm for eps_y. In order to reach these requirements, extreme focusing of the beam is needed in the interaction regions, leading to a vertical beta function of 2mm at the IP. These challenges make the FCC-ee design particularly susceptible to...
FCC-ee will be a precision measurement tool for Z, W, H and t physics with expected luminosities of 2.07 × 10^36 cm−2 s−1 at the Z-pole and 1.3 × 10^34 cm−2 s−1 at the tt ̄ threshold. In order to achieve the foreseen luminosities, a vertical β* of 1 mm to 2 mm is mandatory. Dynamic aperture and frequency maps for the 97.75 km machine are studied. Furthermore, effects of machine misalignments...
The wide range of beam energies of the FCC-ee accelerator presents unique challenges to the interaction region. An update of this design will be discussed with emphasis on the basic choices and its mechanical constraints. A first 3d mechanical design of the IR will be presented addressing some open questions.
Beam-gas induced background has been studied for the MDI region of the FCC-ee at all the operating running energies. Beam loss maps with characterization of the lost particles and full analysis is perfomed with MDISim. Vacuum requirement in the upstream region before the IR and the IR itself is presented. The loss particles can eventually be tracked in the geant4 detector model and luminosity...
FCC-ee is a high luminosity lepton collider designed to cover the beam energy range from the Z pole (45.6 GeV) to the top pair threshold (175 GeV). One of the major issues for this machine is represented by collective effects due to electromagnetic fields generated by the interaction of the beam with the vacuum chamber, which could produce instabilities and limit the machine performance. This...
We analyze effects of the Higher Order Modes (HOM) heating in the FCC ee Interaction Region (IR). Interacting beams excite electromagnetic waves in the complicated geometry of the beam chamber. We discuss a possibility to design a chamber with a minimum RF impedance and suggest using HOM absorbers in the IR to capture the main part of the excited electromagnetic waves.
The bunch by bunch feedback systems for FCC-ee shall be designed on the basis of the experience developed working on the lepton circular colliders in the last two decades. Along the past years a common way to approach these systems has been carried on for PEP-II, KEKB, DAFNE, and, later, for SuperB and SuperKEKB. Nevertheless the advance of the technology as well as the very high performance...
FCC-ee collider rings necessitate top-up injection due to the short luminosity lifetime. Previous studies revealed that the conventional and multipole-kicker injection schemes are applicable. The designs of the injection straight section based on these schemes have been elaborated and will be presented. Further investigations, including feasibility of injection devices, filling scheme, failure...
In this talk CEPC CDR design status with timeline will be presented which includes parameters, beam-beam simulation, collidering ring lattice design, dynamic apertures, booster design, SCRF system design for both collider ring and booster, linac injector design, MDI design, power consumption, site selections, etc. As for CEPC R&D status and plan for TDR will be presented also. Other issues...
CEPC is the future Circular Electron and Positron Collider proposed by China to mainly study the Higgs boson. This paper will present the bean optics design of the collider ring for the concept design report. The compatible beam optics for W and Z mode will be presented as well.
Circular Electron-Positron Collider (CEPC) is a 100 km ring e+ e- collider for a Higgs factory. The injector of CEPC is composed of linac and booster. The linac is a normal conducting S-band linac with frequency in 2856.75 MHz and provide electron and positron beam at an energy up to 10 GeV with bunch charge larger than 1.5 nC and repetition frequency in 100 Hz. The linac design will be...
The requirements for the Final Focus Quadrupoles of FCC-ee are very stringent in terms of field quality and compactness of the design. We are happy to report that we have a design based on the Canted Cosine Theta concept that fullfills all requirements: Very compact design (distance of magnetic centres of the two quadrupoles at the tip 66mm), excellent field quality (less than 0.1units in all...
For precise beam energy measurements at 45 and 80 GeV
the use of resonant depolarization
has been suggested for FCC e+e-.
The principle behind resonant depolarization is that a
vertically polarized beam excited through an oscillating horizontal magnetic field
gets depolarized when the excitation frequency is in a given relationship with the beam
energy.
The studies of the possibility of...
The goal of beam energy calibration is to define central mass energy at the interaction point (IP). The most accurate method is resonant depolarization technique with relative error of 1 ppm in single beam energy calibration. The whole procedure consists of measurement of spin precession frequency, and calculations of beam energy averaged over circumference, beam energy at IP and central mass...
Both future 100 km in circumference electron-positron colliders CEPC and FCC-ee want know beams energies with the extreme precision of 1-2 ppm. This can be done only with the help of the well-known resonant depolarization technique. Still, some beam parameters of these machines, like energy spread and radiative damping decrements, becomes so high near or above 80 GeV per beam, that it is...
