potential CERN facilities to study proton-driven plasma acceleration - PowerPoint Presentation

potential CERN facilities to study proton-driven plasma acceleration Frank Zimmermann Munich MPI, 9 December 2008

CTF-3

existing accelerator chain (LHC beam) PS booster PS SPS LHC final momentum [ GeV/c]2.1264507000protons/bunch [1011]171.31.151.15rms longitudinal emittance [eVs]0.110.030.060.2 (0.08*)rms bunch length [ns]143 1<0.50.25 (0.16*) relative rms energy spread [10-3]0.3210.30.11 (0.07*)rms transverse emittance [mm]2.53.03.53.75bunch spacing [ns]N/A252525 # bunches / cycle4 (4 rings)722882808cycle time1.2 s3.6 s~22 s5-10 h? * w/o longitudinal blow up in the LHC 1 ns = 30 cm, 3x10 -4 ns = 100 m m

PSB SPS SPS+ Linac4 (LP)SPL PS LHC / SLHCDLHC Output energy 160 MeV 1.4 GeV 4 GeV 26 GeV 50 GeV 450 GeV 1 TeV 7 TeV ~ 14 TeV Linac2 50 MeV (LP)SPL : (Low Power) Superconducting Proton Linac ( 4-5 GeV) PS2 : High Energy PS (~ 5 to 50 GeV – 0.3 Hz) SPS+ : Superconducting SPS (50 to1000 GeV) SLHC : “Superluminosity” LHC (up to 10 35 cm -2 s -1 ) DLHC : “Double energy” LHC (1 to ~14 TeV) Proton flux / Beam power present and future LHC injectors PS2 Roland Garoby, LHCC 1July ‘08

layout of new LHC injectors SPS PS2, ~2017 SPL,~2017 Linac4 ~2012 PSR. Garoby, CARE-HHH BEAM07, October’07; L. Evans, LHCC, 20 Feb ‘08

R. Garoby , LHCC 1 July 2008 injector upgrade schedule synchronized with LHC IR upgrades LHC IR phase 1LHC IR phase 22013: PSB with linac42017: SPL+PS2

upgraded accelerator chain (LHC beam) SPL PS2 SPS LHC final momentum [ GeV/c]5504507000protons/bunch [1011]2.5x10-4444rms longitudinal emittance [eVs]7.3x10-70.050.060.2 (0.08*)rms bunch length [ns]1.9x10-41<0.50.25 (0.16*) relative rms energy spread [10-3]0.1810.30.11 (0.07*)rms transverse emittance [mm]0.353.03.53.75bunch spacing [ns]2.8252525 # bunches / cycle200,0001442882808cycle time20 ms2.4 s ~13 s 5-10 h? * w/o longitudinal blow up in the LHC 1 ns = 30 cm, 3x10 -4 ns = 100 m m

phase space at SPL exit M. Eshraqi A. Lombardi

intermediate conclusions the only proton beam which is naturally “short” is the one from the SPL, ~60 micron rms length, with 2.5x10 7 protons / bunch and available at the earliest in 2017 the beam from the SPS must be compressed by a factor 10,000 to obtain rms bunch lengths of 100-200 mm equilibrium bunch length scales with the inverse 4th root of RF voltage and with the 4th root of the momentum compaction factor four other possibilities come to mind: rapid change in momentum compaction factor followed by bunch rotation in mismatched bucket or transverse deflecting cavity?! damping by intrabeam scattering below transition?! coherent electron cooling?!

mismatch pulse fast q uadrupoles t o change momentum compaction, and quickly raise RF voltagebunchshape of linear rf bucketzdextract after ¼ synchrotron oscillation when bunch length is minimumbunch length scales with the square root of pulsed momentum compaction factor

initial momentum compaction ac,initial ~ 0.01 we may hope for a c,new ~ 10-6 initial RF voltage ~ few MVwe may hope for final RF voltage ~ 10x higher→ expect compression by factor 2 x 10-2 /Sqrt(10) ~ 0.006 ~ 1/160

t ransverse deflecting cavity+ b ending system t ransverse deflecting cavitydriftbendingsystem?can something like this work?idea is to convert transverse size into longitudinal size(above schematic ignores x-dependent energy change from crab cavity) c an the plasma w ave excited by c rabbed beam be used for e- acceleration? s hort bunch! or transverse crab cavity followed by “slit”?

c oherent e- cooling CeC proof-of- Principle experiment at RHIC in 2012 damping times in hours: promise of 1-hr damping time at 7 TeV!V. Litvinenko, Y. Derbenevinteresting, but still too small for our purpose

final conclusion to get “high-energy” proton bunch lengths below 1 mm, we can use the beam from the SPL, or we need strong cooling or bunch compression or an x(y)-z 4/6-D emittance exchange transformation or a combination thereof

appendix: thoughts on scattering limits and chances s cattering limits and maximum energy reach of plasma accelerators the return of fixed target experiments?

scattering limits and energy reacha t the plasma-acceleration WG of CLIC08 Andrei S eryi and Tor Raubenheimer reported that 500 GeV acceleration in a plasma was possible, but that 1.5 TeV was excluded by Coulomb scattering – this seemed odd at first glance since Coulomb scattering gets weaker at higher energy scattering limits were previously looked at by Montague & Schnell (1985) and Katsouleas & Dawson (1987)

A. SeryiCLIC08 workshop, Plasma wakefield acceleration working group, CERN, Oct. 2008 B.W. Montague, W. Schnell Multiple scattering and synchrotron radiation in the plasma beat wave accelerator.2nd Int. Workshop on Laser Acceleration of Particles, Los Angeles, CA, Jan 7-18 Jan 1985, AIP Conf.Proc.130:146-155,1985. T. Katsouleas, J.M. Dawson Plasma acceleration of particle beams. 1987. AIP Conf.Proc.184:1798-1828,1989.

m ultiple scattering from my memory i ndeed the normalized emittance grows as the square root of the finalenergy, but no hard limit in energy reach to avoid this limit the b function must increase less than with the the square root of energy (e.g. tapered plasma density)scaling of the multiple scattering limit

bremsstrahlung m ost important vacuum limit at high energy e+ or e- machines this effect would suggest that the total distance t ravelled through the plasma cannot be more than one or a few radiation lengthsfor example X0~10 m for 4x1022 e/cm3using the rough estimate of 30 GV/m for 1x1017e/cm3 this gives an ultimate energy of ~200 TeV

nuclear interaction of protons with plasma? s imilar magnitude as radiation length variation with beam energy?

return of fixed target experiments s ince extremely high gradients are feasible with plasmas but the collision of two such beams may be difficult to achieve, could fixed target experiments become attractive again? Pantaleo Raimondi i n particular they could be interesting for proton driven plasma accelerators with a single proton beam, a single stage, and very high proton and electron energy;possibly high luminosityexperiment might be different from present colliders