Overview & Introduc0on Prospects for a very high energy ep and ea collider Leo Stodolsky Fest Symposium. June 1-2, 2017

Transcription

1 Overview & Introduc0on Prospects for a very high energy ep and ea collider Leo Stodolsky Fest Symposium June 1, Max Planck Ins0tute for Physics

2 Workshop Prospects for a very high energy ep and ea collider We are developing a novel electron accelerafon technology based on plasma wakefields driven by a proton bunch. Experimental program: AWAKE experiment at CERN - > Patric Muggli UlFmate Goal : VHEeP- like accelerator - > MaVhew Wing Today and tomorrow discuss physics opportunifes presented by such a collider.

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7 Symposium in Honor of Leo Stodolsky s 80th Birthday June 1-2, 2017 VHEeP WORKSHOP

8 Novel Accelerator Technology Why is it needed? Ø ConFnue the push to higher energies Ø What projects can provide interesfng parfcle physics along the way? Ø Can we imagine novel physics beyond standard collider paradigm? Ø Challenge is not just reaching higher energies. Also need higher luminosifes for the standard parfcle physics applicafons: d d = s Ø Physics with high energies but low luminosity? p f p i M 2

9 June 1-2, 2017 VHEeP WORKSHOP

10 ParFcle physicists are convinced there are more discoveries to come: Many things not explained in the standard model: why three families maver/anfmaver imbalance neutrinos and neutrino mass hierarchy problem/unificafon dark maver dark energy Need to find ways to explore physics at higher energy scales in a laboratory environment. New accelerafon technology!

11 The Livingston plot shows a saturafon PracFcal limit for accelerators at the energy fronfer: Project size and cost increasing with the energy! New technology needed

12 Plasma Wakefield AcceleraFon Original Proposal: T. Tajima and J. W. Dawson, Phys. Rev. Le+. 43 (1979) 267. Figure from J. Faure et al., Nature 43 Plasma frequency depends only on density 2 p = 4 n pe 2 m k p = p c p = 2 k p =1mm cm 3 n p Produce an accelerator with mm (or less) scale cavifes 100 GeV/m accelerafon demonstrated!

13 New Livingston Plot Plasma Wakefield AcceleraFon

14 ParFcle Physics PerspecFves Physics with a high energy electron beam E.g., search for dark photons Physics with an electron- proton or electron- ion collider Low luminosity version of LHeC Very high energy electron- proton, electron- ion collider Beyond standard par0cle physics Nonlinear QED Cosmic- ray accelerafon Are there fundamental parfcle physics topics for high energy but low luminosity collider or non- collider facilifes? I believe yes! ParFcle physicists will be interested in going to much higher energies and probing intense fields. In general start invesfgafng the parfcle physics potenfal of novel accelerafon schemes. New ideas welcome & needed!

15 Ultra- high energy cosmic rays GZK cutoff for protons traveling at least 50 Mps: ev How did these or even more extreme energies get produced? Possible accelerafon mechanism: plasma wakefield accelerafon

16 Example: strong fields nonlinear QED. InteresFng quesfons to be probed experimentally? Four Options to Study High Field QED at SLAC Option 1: LCLS X rays and 1GeV LWFA beam χ ~0.1 (χ = Ep/Es) Experiments at MEC; Can start now - all hardware ~ exist Option 2: Laser field and 10GeV beam χ ~1-3 ~300TW laser focussed to I ~10 21 W/cm 2 (E ~ V/cm) and Experiments at FACET-II or LCLS; can start in ~1-2 years Option 3: 10GeV FACET-II beam and 300MeV witness injector 175kA FACET-II beam focused to 100nm (E ~ V/cm) χ ~0.1 in e-beam field Experiments at FACET-II; can start in ~3-5 years Option 4: 100GeV collider e - e + with Ep V/cm, χ 10 3! Future facility ~20 year Full breakdown of perturbation theory So far theoretical calculations are impossible N.B. Narozhny, Phys. Rev. D 21, 1176 (1980) V. Yakimenko Tsinghua April 24,

17 Ultra- powerful lasers could allow for laboratory experiments that probe novel physics

18 Novel accelerators based on plasma wakefields, dielectric structures or direct laser accelerafon can bring scienffic opportunifes that reach far beyond colliders, and should therefore be pursued with the highest priority as enablers of discoveries. With AWAKE and proton- driven wakefield accelerafon, we aim to use exisfng infrastructure for the wakefield driver to accelerate electrons to high energy. We want to develop the program of parfcle physics applicafons in parallel. First ideas: Ø Fixed target experiments Ø Low luminosity ep/ea using SPS driver (e.g., LHeC- like) Ø Low luminosity ep/ea using LHC driver Ø For- purpose built proton driver

19 Dark Photon Search Dark maver what is it? So far, no experimental hints on parfcle nature. Interest in low- mass parfcle solufons increasing; e.g., dark photons. Light shining through walls experiments Here, use electron beam. NA64 experiment NA64 expect 10 6 electrons/spill; electrons for 3 months AWAKE electron beam driven by SPS proton bunch. Assuming 10 9 electrons/bunch, would give 3 orders of magnitude increase. M. Wing, Physics Beyond Colliders Kickoff Workshop, 7/Sep/2016, CERN

20 LHeC- like Collider Focus on QCD: Large cross secfons low luminosity (HERA level) enough Many open physics quesfons! Consider high energy ep collider with Ee up to O(50 GeV), colliding with LHC proton; e.g. Ee = 10 GeV, Ep = 7 TeV, s = 530 GeV already exceeds HERA cm energy. Create ~50 GeV beam within m of plasma driven by SPS protons and have an LHeC- type experiment. G. Xia et al., Nucl. Instrum. Meth. A 740 (2014) 173. Clear difference is that luminosity currently expected to be < cm - 2 s - 1.

21 VHEeP (Very High Energy electron- Proton collider) One proton beam used for electron accelerafon to then collide with other proton beam Luminosity ~ cm - 2 s - 1 gives ~ 1 pb 1 per year. Electron energy from wakefield accelerafon by LHC bunch Choose E e = 3 TeV as a baseline for a new collider with E P = 7 TeV yields s = 9 TeV. Can vary. - Centre- of- mass energy ~30 higher than HERA. - Reach in (high) Q 2 and (low) Bjorken x extended by ~1000 compared to HERA. - Opens new physics perspecfves VHEeP: A. Caldwell and M. Wing, Eur. Phys. J. C 76 (2016) 463 October 11, 2016 NAPAC, Chicago A. Caldwell, K. V. Lotov, Phys. Plasmas 18, (2011)

22 e Electron Proton ScaVering in the Proton Rest Frame l e Mass of partonic system l ~c E For Q 2 m 2,wehave E m2 + Q 2 2 Photon energy E Q2 2 l 2 ~c Q 2 ~c xm P.

23 Small- x, small Q 2 Larger- x, larger Q 2

24 Photon-Proton Cross Section Photon-Proton Cross Section Increase of the photon- proton cross secfon with coherence length. Cross secfons increasing with energy - > do not require large luminosity to probe this physics. A. Caldwell, New J.Phys. 18 (2016) no.7,

25 OK let s start the workshop.