ANAR2017 Advanced and Novel Accelerators for High Energy Physics Roadmap Workshop 2017 25-28 April 2017, CERN 6-2-024 - BE Auditorium

Organised at the initiative of the ICFA panel for Advanced and Novel Accelerators Organizing Committee (OC) ICFA Panel members Brigitte Cros (chair), CNRS- U PSud, France Patric Muggli, MPP, Germany Bruce Carlsten, LANL, USA Massimo Ferrario, INFN, Italy Brian Foster, U Hamburg, Oxford, DESY, Germany Ryoichi Hajima, NIQRST, Japan Dino Jaroszynski, U Strathclyde, UK Philippe Piot, NI U (USA), Fermi Lab. James Rosenweig, UCLA, USA Carl Schroeder, LBNL, USA Chuanxiang Tang, Tsinghua U, China Mitsuru Uesaka, U Tokyo, Japan Mitsuhiro Yoshida, KEK, Japan Other members Ralph Assmann, DESY, Germany Edda Gschwendtner , CERN, Switzerland Bernhard Holzer, CERN, Switzerland Sponsored by http://www.lpgp.u-psud.fr/icfaana/front-page

Goal of the workshop To define an international roadmap towards colliders based on advanced accelerator concepts, including intermediate milestones, and to discuss the needs for international coordination. https://indico.cern.ch/event/569406/overview

Outline Scientific frame Challenges and global roadmap items e- e+ Collider for HEP 4 concepts (WG), status & proposed roadmaps Challenges and global roadmap items Review of strategy worldwide Next steps toward a collider roadmap

Challenging question for the community of ANA Can we envisage the delivery of an Advanced linear collider at >1TeV (10 TeV) in 2035? Electron- positron Collider Parameters defined for/by HEP (Luminosity) Four different concepts of Advanced Accelerators were discussed

Advanced Accelerator concepts discussed in 4WGs At this workshop Wakefields driven in plasma by intense laser beams : LWFA Wakefields driven in plasma by particle beams: PWFA Wakefields driven in dielectric tubes by particle beams: DWA Wakefields driven in dielectric structures by short-pulse lasers: DLA

Status/roadmap LWFA Excellent status from Mike Downer, and comparison of 4 concepts WG LWFA coordinators : Arnd Specka (CNRS), Dan Gordon (NRL), Carl Schroeder (LBNL)

Normalized Trans-verse emittance Repetition Rate & Repeatability Current Status of LWFA Electron Bunch Properties M. Downer intro talk ANAR2017 Property State of Art* Reference Remarks Energy 2 GeV (± 5%, 0.1 nC) 3 GeV (±15%, ~0.05 nC) 4 GeV (±5%, 0.006 nC) Wang (2013) - Texas Kim (2013) – GIST Leemans (2014) - LBNL Accelerates from E ≈ 0 Energy Spread 1% (@ .01 nC, 0.2 GeV) 5-10% Rechatin (2009a) – LOA more typical, many results 0.1% desirable for FELs & colliders Normalized Trans-verse emittance ~ 0.1 π mm-mrad Geddes (2008) - LBNL Brunetti (2010) - Strathclyde Plateau (2012) - LBNL Measurements at resolution limit Bunch Duration ~ few fs Kaluza (2010) – Jena (Faraday) Lundh (2011) – LOA; Heigoldt (2015) – MPQ/Oxford (OTR) Zhang (2016) – Tsinghua Charge 0.02 nC @ 0.19 GeV ±5% 0.5 nC @ 0.25 GeV ±14% Rechatin (2009b) – LOA Couperus (2017) - HZDR Beam-loading achieved. FOM: Q/∆E ? Repetition Rate & Repeatability ~ 1 Hz @ > 1 GeV 1 kHz @ ~ 1 MeV He – UMIch (‘15); Salehi (‘17) – UMd; Guénot (‘17) -- LOA Limited by lasers & gas targets • Should additional beam properties be included? • Are the state-of-art numbers accurate? • Have I omitted important references? * No one achieves all of these simultaneously! • Brunetti, PRL 105, 215007 (‘10) • Couperus, submitted (‘17) • Geddes, PRL 100, 215004 (‘08) • He, Nat. Comms 6, 7156 (2015) • Rechatin, PRL 103, 194804 (‘09b) • Salehi, Opt. Lettt. 42, 215 (‘17) • Wang, Nat. Comms 4, 1988 (2013) • Zhang, PRST-AB 19, 062802 (2016) • Heigoldt, PR-STAB 18, 121302 (‘15) • Kaluza, PRL 105, 115002 (‘10) • Kim, PRL 111, 165002 (2013) • Leemans, PRL 113, 245002 (2014) • Lundh, Nat. Phys. 7, 219 (2011) • Rechatin, PRL 102, 164801 (2009) Current Status of LWFA Positron Properties: no results yet 2/31

WG LWFA

Status/roadmap PWFA Status from M Hogan summary 2 roadmaps for electron/proton driven WG PWFA coordinators : M Hogan (SLAC), Allen Caldwell (MPP), and Edda Gschwendtner (CERN)

Status/roadmap 3 Structure-based wakefield acceleration Roadmap includes two general schemes WG (DWA) or SWFA coordinators : Philippe Piot (FNAL/NIU) and Paolo Craievich (PSI)

Status/roadmap 4 Dielectric Laser accelerator Overview by Simakov, conclusions from WG4 WG DLA coordinators: Joel England (SLAC), Josh McNeur (FAU Erlangen), Bruce Carlsten (LANL)

Status/roadmap 4 Dielectric Laser accelerator

Conclusions from WG4

M. Downer intro talk ANAR2017 LWFA and PWFA/DWA/DLA: Comparisons & Contrasts* M. Downer intro talk ANAR2017 Property LWFA PWFA DWA DLA Stand-alone? (i.e. no RF accelerator) YES NO Energy Gain Achieved 0  4.25 GeV 20  30 GeV 40  80 GeV smaller much smaller Accelerating Gradient ~1 GeV/cm ~ 0.1 GeV/cm Dephasing Limited? Positrons accelerated? NOT YET Wall-plug efficiency 10-5 (@ 1GeV ± 10%) 10-7 (@ GeV ± 0.1%) • Any help with completing the PWFA/DWA/DLA parts of the table is appreciated. * Intended to highlight areas where the approaches differ, not to promote one approach over another. 3/31

Challenges and global roadmap items : 20-25 Ys Collider CDR and TDR 10 Ys x10 Improved beam quality at higher energy - Optimized e- sources - e+ source (concepts) Adressing Specific challenges : micron scales: Apertures (DLA) Synchro (LWFA) average power Stability 5 Ys Injector, Accelerator stages with reliable parameters - Optimize all parameters for e- e+ acceleration Adressing Specific challenges : Staging Efficiency BDS

From W.Leemans talk

Our next tasks will be to merge roadmaps (Scientific/ Strategic visions) trigger /foster community interest to the topic

Review of strategy worldwide was discussed The USA have a clear strategy driven by DoE Asia is oriented towards short term application (radiation) Europe provides incentive for coordinated strategies through funding of joint projects National strategies are not formalized everywhere

Personal vision for PWA in Europe (cont’d) Recommendation From R. Aleksan talk Be ready to propose the construction of a user oriented accelerator in Europe in 2018-2019 with credible site(s) Why : to demonstrate the usability and appropriateness of PWA to provide a clear option for States and decision makers to be included in Roadmap such as ESFRI, PP, Light Sources… to be included in H2020 calls of Preparatory Phases Who : All partners interested in constructing a user-oriented facility including at government levels How : through EuPRAXIA, the success of which is mandatory Engage in the preparation of a HE frontier DS proposal Why : to (possibly) be included in Roadmap such as ESFRI, PP, Light Sources… to be included in H2020 calls of DS in 2019 Who : All partners interested in studying a user-oriented energy frontier facility, including at government levels How : Set up a Task Force, Down selecting technologies for a proposal!

Next steps toward a collider roadmap We (OC) will chart a scientific roadmap from discussed items Output of the workshop: report summer 2017 Towards a proposal for an advanced linear collider A more detailed/technical document will be prepared for the European Strategy Research Group, by the end of 2018 Organisation to prepare it: a series of workshops to discuss and finalize the roadmap is being planned (WG8 EAAC, Jan-May 2018 at JAI?, at AAC 2018?) A study group to steer this activity has to be set-up: volonteers welcome

Thank you for your attention

From the US Strategy The significant cost of R&D facilities strongly influences the roadmap for advanced accelerator R&D. •Makes difficult (expensive) pursuit of multiple approaches in parallel. •Drives early (too early?) down-selection of approaches. •Cost strongly influenced the ARD Subpanel, which was charged to meet specific budget scenarios. •An international AARD program, with some level of international coordination, is more capable of mounting the future facilities needed to explore multiple promising approaches.

Personal vision for PWA in Europe Objectives (cont’d) PWA community should augment the R&D in a coordinated way and use the available and planned EC instruments A European PWA R&D roadmap and strategy using the infrastructures in Europe, i.e. What R&D should be done, who does it and where… PWA should be visible at the EC level, not only for getting some funds, but also to gain credibility PWA should use the EC tools as lever arms for getting additional national funding,