Hosted at KIT (Karlsruhe Institute of Technology) Local organization by KIT and GSI

Introduction and motivation

Workshop organized in the framework of: EuCARD-2 (Integrating Activity Project for coordinated Research and Development on Particle Accelerators, co-funded by the European Union) In particular within “Extreme Rings” (XRING), a networking task of EuCARD-2 Work Package 5 “Extreme Beams” (XBEAM; http://cern.ch/xbeam), targeted at creating synergies between different accelerator communities in order to enhance accelerator R&D at the forefront of global research Previous events in the same cycle: Beam dynamics meets magnets, Dec 2013, Darmstadt Beam dynamics meets magnets II, Dec 2014, PSI Space charge, Mar 2015, Oxford Advanced optics control, Feb 2015, CERN Beam dynamics meets diagnostics, Nov 2015, Florence Slow extraction, Jun 2016, GSI

66 registrants from different accelerator communities (e. g 66 registrants from different accelerator communities (e.g. light sources, colliders, ion storage rings, FELs) as well as from companies, and with different backgrounds (beam dynamics, vacuum, surface, collimation) 32 presentations (no parallel sessions)

Photo-electron emission (from synchrotron radiation) The characteristics of the vacuum system impact beam dynamics in several different ways: The beam interacts with residual gas: low pressures are needed to achieve good beam lifetime and prevent beam emittance growth The vacuum system constitute a large fraction of what the beam “sees” while circulating in the accelerator (chambers, flanges, tanks) Big contributions to the machine impedance determining stability limits and beam induced heating Properties of surfaces exposed to the beams are responsible for several effects: Gas desorption due to particle losses, heating, photon or electron impacts Photo-electron emission (from synchrotron radiation) Secondary Electron Emission, responsible for electron clouds These effects determine many aspects of design, commissioning and operation of modern high performance particle accelerators Collaboration between vacuum scientists and beam physicists is crucial Related contributions Basics of beam dynamics and vacuum (G. Rumolo) Residual gas and surface in vacuum specification for particle accelerators (O. Malyshev) Impact of impedance effects on beam chambers specifications (E. Metral)

A few highlights

Several contributions from low-emittance ring community The quest for ultra low emittances translates into smaller and smaller beam chamber size Impedance budget becomes more and more critical Difficult to meet the tight vacuum specifications with conventional pumping  large scale usage of NEG coatings (originally developed at CERN for the LHC), efforts ongoing to improve coating quality for flat and very small chambers SOLEIL ALBA Impact of vacuum on beam performance observed especially during commissioning or after installation of new equipment: Fast Beam Ion Instabilities Poor lifetime Lifetime Pressure Related contributions Beam dynamics & vacuum challenges in present light sources and future low emittance rings (R. Nagaoka) The impact of vacuum quality in light sources: beam lifetime and fast ion instabilities (U. Iriso) XFEL impedance budget, energy loses/spread and realized technical solutions to minimize the effects (M. Dolhus) The vacuum system at the upcoming SIRIUS light source in Brazil (T. Mendez Da Rocha) The vacuum system of MAX IV (E. Al-Dmour) Advances in NEG coating technologies (P. Manini) Challenges of vacuum chambers with adjustable gap for SC undulators (C. Boffo)

Avalanche effects can be triggered: Interaction with the residual gas Several contributions form the ion accelerators and storage rings community Vacuum quality particularly critical when working with intermediate charge states Avalanche effects can be triggered: Interaction with the residual gas Charge state exchanges Beam losses Gas desorption Efficient collimation systems are necessary to control this kind of effects Related contributions Dynamic vacuum and beam loss challenges at GSI and FAIR (C. Omet) Vacuum system of SIS100 (S. Wilfert) Dynamic vacuum challenges for heavy-ion accelerators (M. Bender) Calculation about ion trapping in HESR (F. Hinterberger) Vacuum generation in electron cooling devices (A. Bubley)

Several contributions form the high energy collider community HL-LHC For superconducting machines one key challenge is the design of beam screens in order too: Absorb large beam-induced loads (impedance, synchrotron radiation e-cloud, collision debris) Provide efficient pumping Minimize e-cloud effects New ideas being considered for FCC: Coatings with High Temperature Superconductors Exploit chamber reflectivity to transport synchrotron radiation loads to warm regions FCC Related contributions Vacuum issues in IR of an electron-ion collider (C. Montag) The HL-LHC vacuum and beam dynamics issues (V. Baglin) Beam dynamics & vacuum challenges in FCC (F. Zimmermann) The vacuum system of the future circolar collider: challenges and innovations (R. Kersevan) The beam pipe for FCC pp: design and expected results from tests at ANKA (R. Kersevan) Alternative concept for synchrotron radiation protection for future proton colliders (R. Cimino) Research on high temperature superconducting coatings for FCC (S. Calatroni) Calculation and measurement of Non-Gaussian beam Tails due to scattering on residual gas targets (S. Gluckov)

Work-function used to crosscheck measurement methods One session dedicated to e-cloud effects Presently an issue especially for high luminosity colliders (LHC and SuperKEKB) Accurate knowledge of the surface behavior (characterization of the secondary emission process) fundamental for making solid prediction Systematic laboratory studies are required Details that are very difficult to measure (e.g. secondary emission at low energy) can make a significant difference on the cloud buildup process Significant effort in the surface community to reliably measure these quantities Work-function used to crosscheck measurement methods Assume for Au: Φ=5.2eV Get: ΦAl =4.0 eV ΦCu= 4.4 eV ΦHOPG=4.4eV Related contributions Electron cloud issues (G. Iadarola) SEY of surfaces: laboratory measurements, influence of temperature and magnetic field (M. Taborelli) Electron cloud effects and ion effects in SuperKEKB and FCC (K. Ohmi) Review of electron cloud at CESR and future machines for bright beams (S. Poprocki)

HL-LHC ISIS H0 absorber SIS 100 One session dedicated to collimation systems HL-LHC ISIS H0 absorber SIS 100 Related contributions Overview of conventional and advanced collimation systems (S. Redaelli) The SIS 100 collimation system (V. Kornilov) Upgrade of the 70 MeV H-injection line at ISIS (B. Jones)

Thanks for your attention! These are just a few highlights… All the material of the workshop is available at: https://indico.gsi.de/internalPage.py?pageId=2&confId=5393 Thanks for your attention!