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A PWFA gamma-gamma collider A fast track towards a PWFA-LC?

A PWFA gamma-gamma collider A fast track towards a PWFA-LC?. Erik Adli University of Oslo, Norway in collaboration with : Philipp Roloff (CERN), Daniel Schulte (CERN), Ben Chen (CERN and University of Oslo). EAAC2019 - The European Advanced Accelerator Concepts Workshop Elba Island, Italy

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A PWFA gamma-gamma collider A fast track towards a PWFA-LC?

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  1. A PWFA gamma-gamma colliderA fast track towards a PWFA-LC? Erik Adli University of Oslo, Norway in collaboration with : Philipp Roloff (CERN), Daniel Schulte (CERN), Ben Chen (CERN and University of Oslo) EAAC2019 - The European Advanced Accelerator Concepts Workshop Elba Island, Italy September 17, 2019

  2. An ultimate application for PWFA: a Multi-TeV collider. Simulated e- e+ top-quark pair at 380 GeV (CLIC Collaboration) A high-energy, high-luminosity electron-positron linear collider will provide precision measurements, complementing the LHC results. It will increase our understanding of the TeV-scale, and is sensitive to beyond-Standard Model physics above the LHC energy scale. Projects : A simulated top-quark pair at 380 GeV (CLIC Collaboration) The International Linear Collider, ILC Main linac technology: super conducting RF 1.3 GHz SW cavities, 31.5 MV/m Nominal design for ECM = 0.5 TeV, 31 km (250 GeV to 1 TeV) The Compact Linear Collider, CLIC Main linac technology: two-beam scheme. Normal conducting Cu RF 12 GHz TW cavities, 100 MV/m. Nominal design for ECM = 3 TeV, 48 km (380 GeV to 3 TeV) Despite a rich physics program, the current global funding climate makes the realization of the above colliders challenging. Going to even higher energy (multi-TeV) seems not so realistic. This talk: highlight a ”fast track” towards a compact, cheaper Multi-TeV collider.

  3. Why use plasma for a Multi-TeV collider? Plasma wakefield acceleration gives promise for an alternative route to TeV-scale e- e+ collisions, possibly enabling a higher energy reach, or a lower cost per energy. To be attractive, concepts put forward should show improvement of some form with respect to the existing projects (ILC, CLIC). Equally important as the collision energy is the luminosity. Physics studies show that the luminosity requirements set for ILC and CLIC remains as high, or higher, at higher collision energies. P. Roloff (CERN), CLIC WG on Novel Accelerator Technologies, https://indico.cern.ch/event/700647/ General formula: CLIC 3 TeV:PAC = 500+ MW For linear colliders : • Possibilities for improvement for a PWFA-LC? • Minimize footprint (cost) • Reduce overall cost • Minimize vertical emittance • Minimize vertical focusing function • Maximize wall-plug-to-beam efficiency • Short bunches, but lower limit must be checked due to beamstrahlung (not shown in scaling) • Keep luminosity target! • A PWFA-LC that costs one O.M less but gives several O.M. less luminosity would likely have limited interest. Taking into account beam strahlung : D. Schulte, IPAC 2002 K. Yokoya, P. Chen, KEK, 1991 CLIC CDR, 2012 sy2 = byey

  4. Focus here on PWFA for the linac : the longest and most costly component of a collider • Some preliminary concepts/considerations for different technologies : • J. B. Rosenzweig et al., Towards a plasma wake field acceleration-based linear collider, NIM A410 (1998) 532-543 • A. Seryi et al., A CONCEPT OF PLASMA WAKE FIELD ACCELERATION LINEAR COLLIDER (PWFA-LC), SLAC-PUB-13766 • C. B. Schroeder, E. Esarey and W. P. Leemans, Phys. Rev. ST Accel. Beams 15, 051301 (2012) • E. Adli et al., A beam driven plasma-wakefield linear collider: from Higgs factory to multi-TeV, SLAC-PUB-15426 • W. Gai et al., CONSIDERATIONS FOR A DIELECTRIC-BASED TWO-BEAM- ACCELERATOR LINEAR COLLIDER • ... 2013

  5. Status of PWFA-LC collider studies • The 2013 PWFA-LC paper was scrutinized by the conventional accelerator community (Fermilab, CLIC, ILC), which led to a number of constructive comments, stimulating further work and progress in a number of areas. • A few topics where progress was done : • drive beam distribution • drive beam generation • staging • plasma lenses • transverse instabilities • transverse tolerances • Summarized in E. Adli, Phil. Trans. R. Soc. A 377: 20180419 (2019) However, currently no clear regime for high-efficiency, high-charge, nm emittance positron acceleration. It makes little sense to proceed to any level of e-e+ collider without knowing the positron acceleration mechanism, since the overall machine parameters will depend heavily on the acceleration mechanism (CLIC, ILC).

  6. Possible alternative to e- e+ collider: g-g collider? High energy photons are produced by Compton back-scattering off TeV e- beams : The photon spectra has a peak at about 0.8Ee- V. Telnov P. Roloff, Physics opportunities and luminosity requirements at very high energies https://indico.cern.ch/event/700647/ The physics case for an g-gcollider as complement to e- e+ colliders have been studied earlier. However, only limited work has been done x the potential for a g-gcollider as the only Multi-TeV collider. This was recently been studied recently by the CLIC project, as part of CLIC upgrade options.

  7. Particle physics case for a Multi-TeV gg collider P. Roloff (CERN), CLIC WG on Novel Accelerator Technologies, https://indico.cern.ch/event/778083/ Cross sections for 10 TeV colliders • Direct discovery in pair production of charged particles, requirements on integrated luminosity same order of magnitude as for electron-positron collisions • Promising opportunities for precision measurements in multi-boson production (will be explored further) • gg ideal to study light-by-light scattering • Some unique opportunities in electron-photon interactions

  8. Multi-TeV gg as a first stage? A e-e+ Higgs factory seems to be the choice for the first next big collider An e-e+ collider can measure Higgs properties in a model independent way. A gg collider can not (nor a pp). A gg collider cannot replace an e-e+ as the first stage Higgs factory See plenary talk by Steinar Stapnes on Thursday. g g

  9. Possible long term HEP strategy : Higgs-energy e-e+ followed by a gg scenario. For example“Reuse” a 380 GeV CLIC machine (11 km) as a gg PWFA-LC.(or reuse 250 GeV ILC, but crossing angle an issues) CLIC 380 GeV The following features of the CLIC machine may upgraded with future technology : – The Main Linacs tunnels of 2x3.5km. Assuming 1 GV/m for plasma technology, beams of up to 3.5 TeV could be produced– The crossing angle of 20 mrad optimal for 3 TeV CM energy collisions, also likely to be a good choice for higher c.m. energy collisions. Compatible with high-energy γγ collisions – Could be possible to modify parts of the CLIC Drive-Beam Complex to produce appropriately spaced drive beams for a PWFA-LC– The injectors providing 9 GeV low emittance electron and positron beams, could also inject into a main linac based on future technology – Tolerances on alignment and stability, both transverse and longitudinal: needs to be reworked for a PWFA-LC See WG6, Tuesday 18h20 B. Chen, Modeling and simulation of transverse wakefields in PWFA CLIC Project Implementation Plan (CERN-2018-010-M,  arXiv:1903.08655)

  10. gg-collider: many challenges (only a few of them shown here) Laser challenges : From K. Kim and A. Sessler, LBNL 39093 lL > 4 mm x Ee (TeV) sr,L~ few mm 1 J at 1 ps (1 TW) fast rep rate K. Yokoya,NIM A 455 (2000) 25 Interaction region challenges: Conversion point less than 1 cm from the collision point. Minimize e-e- background. Embarking on a PWFA gg collider design would likely interest conventional accelerator experts, plasma acceleration experts and laser experts alike.

  11. A fast track towards a PWFA-LC ? • Crucial difference between gg and e-e+ : the ingredients to study a PWFA-LC gg are in place • we know how to proceed. As opposed to for the e-e+ option. • For a real design large resources are needed. However, to establish rough parameters for a gg PWFA-LC, I see a few main items to investigate, required only limited resources : • establish the physics case • establish the impact of transverse wakefields on collider stability and tolerances • a first iteration of overall collider parameters, taking into account transverse wakefields • the three efforts can go on in parallel. • We don't need to wait for next round of experiments at FF, FACET or AWAKE • instead assume “best” experimental outcome (experiment as good as paper studies) • Of course we should keep on investigating positron PWFA, but .,. • A Multi-TeV gg-collider may be the fast track option towards a PWFA-LC. • A “short” e-e+ based on conventional technology may be preferred as the first stage.

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  13. For comparison, to highlight opportunities and challenges: key numbers for CLIC 3 TeV, as the technology uses a two-beam acceleration scheme (as does PWFA). gradient 100 MV/m L = 10 L = 1034 /cm2/s e*n,y = 20 nm s*y = 1 nm s*z = 44 um N = 600 pC/e nb = 312 @ 2 GHz frep = 50 Hz Efficiencies: AC to DB : 141/255 = 55% DB to rf wake : (28+86)/141 = 81% Rf wake to MB : 28/141 = 25% -> DB to MB = 28/141 = 20% -> AC to MB = 28/255 = 11% Power flow chart: from CLIC CDR (2012) • Notes: • Aux. systems power not shown • Current numbers slightly different than CDR CLIC After the two-beam module DB dump Before the two-beam module 6.7% 100% 20% ACC wall and dump 61% DB WB

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