Publications associées à Grazing function g and collimation angular acceptance

Studies of crystal collimation for heavy ion operation at the LHC

At CERN's Large Hadron Collider (LHC), proton and heavy-ion beams are accelerated to multi-TeV energies to be collided for the needs of the scientific community around the world. The total stored beam energy of tens to hundreds ofMJ creates potential threa ...

EPFL2024

Energy-Efficient Particle Accelerators for Research

Mike Seidel

Particle accelerators are the drivers for large-scale research infrastructures for particle physics but also for many branches of condensed matter research. The types of accelerator-driven research infrastructures include particle colliders, neutron, muon ...

2024

Collimation simulations for the FCC-ee

Tatiana Pieloni, Félix Simon Carlier, Guillaume Clément Broggi, Milica Rakic, Giovanni Iadarola, Bruce Roderik

The collimation system of the Future Circular Collider, operating with leptons (FCC-ee), must protect not only the experiments against backgrounds, but also the machine itself from beam losses. With a 17.8 MJ stored energy of the electron and positron beam ...

Iop Publishing Ltd2024

Impact of beam-coupling impedance on the Schottky spectrum of bunched beam

Tatiana Pieloni, Nicolas Frank Mounet, Christophe Emmanuel R. Lannoy

The Schottky monitors of the Large Hadron Collider (LHC) can be used for non-invasive beam diagnostics to estimate various bunch characteristics, such as tune, chromaticity, bunch profile or synchrotron frequency distribution. However, collective effects, ...

Iop Publishing Ltd2024

Generalised Kerr Microcomb Physics in Synchronously Driven Systems

Miles Henry Anderson

In this thesis, the generation of microcombs under complex, non-trivial, and/or higher-order cavity conditions is explored, both in theory & simulation, and in practical experimentation. Pulse-driving of microresonators is investigated for the generation ...

EPFL2023

Dissipative Solitons and Switching Waves in Dispersion-Modulated Kerr Cavities

Rui Ning Wang, Tobias Kippenberg, Miles Henry Anderson, Alexey Tikan, Aleksandr Tusnin, Alisa Davydova

We theoretically and experimentally investigate the formation of dissipative coherent structures in Kerr nonlinear optical microresonators, whose spectrum encompasses an integrated dispersion that exceeds the cavity free-spectral range. We are able to acce ...

American Physical Society2023

A weakly nonlinear amplitude equation approach to the bypass transition in the two-dimensional Lamb–Oseen vortex

François Gallaire, Yves-Marie François Ducimetière

We analytically derive an amplitude equation for the weakly nonlinear evolution of the linearly most amplified response of a non-normal dynamical system. The development generalizes the method proposed in Ducimetière et al. (J. Fluid Mech., vol. 947, 2022, ...

Cambridge University Press2023

Zero dispersion Kerr solitons in optical microresonators

Tobias Kippenberg, Junqiu Liu, Miles Henry Anderson, Wenle Weng, Alexey Tikan

Solitons are shape preserving waveforms that are ubiquitous across nonlinear dynamical systems from BEC to hydrodynamics, and fall into two separate classes: bright solitons existing in anomalous group velocity dispersion, and switching waves forming 'dark ...

Nature Research2022

Coordinate parameterisation and spectral method optimisation for Beltrami field solver in stellarator geometry

David Pfefferlé, Aravind Kumar Chandiran, Antoine Baillod, Ajay Kumar

The numerical solution of the stepped pressure equilibrium (Hudson et al 2012 Phys. Plasmas 19 112502) requires a fast and robust solver to obtain the Beltrami field in three-dimensional geometry such as stellarators. The spectral method implemented in the ...

2020

Electron Spin Resonance Magnetometers for Particle Accelerators

Anthony Jean Beaumont

CERN is the European Organization for Nuclear Research located in Geneva, Switzerland. Its main goal is to explore fundamental physics and it exists primarily to provide physicists the necessary tools for doing this, namely accelerators. These tools bring ...

EPFL2020

On the asymptotic behavior of the solutions to parabolic variational inequalities

Maria Colombo

We consider various versions of the obstacle and thin-obstacle problems, we interpret them as variational inequalities, with non-smooth constraint, and prove that they satisfy a new constrained Lojasiewicz inequality. The difficulty lies in the fact that, ...

2020

A novel approach to Landau damping of transverse collective instabilities in future hadron colliders

Michael Schenk

Transverse collective instabilities induced by the beam-coupling impedance of the accelerator structure lead to beam quality degradation and pose a major limitation to the machine performance. Landau damping, a powerful stabilising mechanism that can be em ...

EPFL2019

Mitigation of intensity limitation in the CERN SPS using a double RF system

Massimiliano Schwarz, Joël Repond

The Super Proton Synchrotron (SPS) at CERN is the injector of the Large Hadron Collider (LHC). Multi-bunch instabilities limit the intensity of the beam that can be accelerated to 450 GeV in the SPS and transferred to the LHC. Without mitigation measures, ...

2019

Micro-focused MHz pink beam for time-resolved X-ray emission spectroscopy

Andre Al Haddad, Christoph Bostedt

The full radiation from the first harmonic of a synchrotron undulator (between 5 and 12 keV) at the Advanced Photon Source is microfocused using a stack of beryllium compound refractive lenses onto a fast-moving liquid jet and overlapped with a high-repeti ...

2019

Polychromatic Cherenkov Radiation Induced Group Velocity Symmetry Breaking in Counterpropagating Dissipative Kerr Solitons

Tobias Kippenberg, Erwan Guillaume Albert Lucas, Wenle Weng

High-order-dispersion-induced dispersive waves emitted by dissipative Kerr solitons are frequently observed in microresonator frequency comb generation. Also known as soliton Cherenkov radiation, this type of dispersive wave plays a critical role in comb s ...

AMER PHYSICAL SOC2019

The index of singular zeros of harmonic mappings of anti-analytic degree one

Robert Gerhard Jérôme Luce

We study harmonic mappings of the form , where h is an analytic function. In particular, we are interested in the index (a generalized multiplicity) of the zeros of such functions. Outside the critical set of f, where the Jacobian of f is non-vanishing, it ...

TAYLOR & FRANCIS LTD2021

High-gradient and high-efficiency linear accelerators for hadron therapy

Stefano Benedetti

Hadron beams - approximately 200 MeV protons and 400 MeV/u fully stripped carbon ions - are better suited to treat deep-seated tumours than X ray beams - produced by electrons accelerated by linear accelerators (linacs) to 5-25 MeV - because they leave the ...

EPFL2018

Solitary waves in longitudinally wrinkled and creased helicoids

Florian Paul Robert Maurin

Elastic ribbons subjected to twist and stretch handle multiple morphological instabilities, amongst others, the longitudinally wrinkled and creased helicoids are investigated in the present paper as promising periodic nonlinear waveguides. Modeling the rib ...

Elsevier2017

Characteristics of solitary waves on a falling liquid film sheared by a turbulent counter-current gas flow

Nicolas Igor Jacques Kofman

We report an experimental investigation of a falling water film sheared by a turbulent counter-current air flow in an inclined rectangular channel. Film thickness and wave velocity measurements associated with visual observation are conducted to study the ...

Elsevier2017

Octave-spanning dissipative Kerr soliton frequency combs in Si3N4 microresonators

Michail Zervas, Tobias Kippenberg, Martin Hubert Peter Pfeiffer, Erwan Guillaume Albert Lucas, Maxim Karpov, Hairun Guo, Junqiu Liu, Clemens Herkommer

Octave-spanning, self-referenced frequency combs are applied in diverse fields ranging from precision metrology to astrophysical spectrometer calibration. The octave-spanning optical bandwidth is typically generated through non-linear spectral broadening o ...

Optical Soc Amer2017