Reinventing the accelerator for the high-energy...
Transcript of Reinventing the accelerator for the high-energy...
Reinventing the accelerator for the high-energy frontier
Reinventing the accelerator for the high-energy frontier
J. B. RosenzweigUCLA Department of Physics and Astronomy
SUSY 2006, June 16, 2006
J. B. RosenzweigUCLA Department of Physics and Astronomy
SUSY 2006, June 16, 2006
SUSY 2006
Particle physics and particle accelerators have a shared history, destiny
Particle physics and particle accelerators have a shared history, destiny
Key discoveries associated with innovations in accelerator and beam capabilities,
Lawrence (cyclotron, radioactive elements)Rubbia and van der Meer (antiproton cooling, W/Z)Tevatron…
Consensus in the field emphasize the centrality of accelerator-based HEP
Large Hadron Collider (LHC) International Linear Collider (ILC)
Key discoveries associated with innovations in accelerator and beam capabilities,
Lawrence (cyclotron, radioactive elements)Rubbia and van der Meer (antiproton cooling, W/Z)Tevatron…
Consensus in the field emphasize the centrality of accelerator-based HEP
Large Hadron Collider (LHC) International Linear Collider (ILC)
SUSY 2006
Schematic view of accelerators for particle physics; related fields
Schematic view of accelerators for particle physics; related fields
ElectrostaticAccelerators
Betatron
Cyclotron
Ion LinearAccelerators
Synchrotron CircularCollider
SuperconductingCircularCollider
Electron LinearAccelerators
Electron LinearColliders
MuonCollider?
VLHC?Medicine Light sources
(3rd
Generation)
Nuclear physics
X-ray FEL
Laser/Plasma Accelerators?
Ultra-High Energy LC?
FFAG,etc.
20301930
SUSY 2006
Now mature (read: aging) ideas have driven HEP accelerators forward…
Now mature (read: aging) ideas have driven HEP accelerators forward…
Induction acceleration (betatron)Resonant electromagnetic acceleration (cyclotron)Normal and superconducting RF cavities (linac, synchrotron)Alternating gradient magnetic focusing (synchrotron)Fixed targetry, exotic particle sources (synchrotron, linac)Colliding beams in synchrotrons (circular collider)Colliding beams in linear accelerators (linear collider)Cooling of particle beam phase space (colliders)Particle polarization (fixed targets/colliders)
Induction acceleration (betatron)Resonant electromagnetic acceleration (cyclotron)Normal and superconducting RF cavities (linac, synchrotron)Alternating gradient magnetic focusing (synchrotron)Fixed targetry, exotic particle sources (synchrotron, linac)Colliding beams in synchrotrons (circular collider)Colliding beams in linear accelerators (linear collider)Cooling of particle beam phase space (colliders)Particle polarization (fixed targets/colliders)
Are these enough for the future?Do we need to re-invent the accelerator?
Are these enough for the future?Do we need to re-invent the accelerator?
SUSY 2006
Colliders and the energy frontierColliders and the energy frontier
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Fixed target energy for particle creation
Colliding beams (e.g. e+e-) makes lab frame into COM…
Exp’l growth in equivalent beam energy w/time
Livingston plot: “Moore’s Law”for acceleratorsWe are now falling off plot!
Challenge in energy, but not only…luminosity as well
Fixed target energy for particle creation
Colliding beams (e.g. e+e-) makes lab frame into COM…
Exp’l growth in equivalent beam energy w/time
Livingston plot: “Moore’s Law”for acceleratorsWe are now falling off plot!
Challenge in energy, but not only…luminosity as well
UPC ≅ 2Ubmtc2
UPC = 2Ub
SUSY 2006
Present limitations of collider energyPresent limitations of collider energySynchrotron radiation power loss
Forces future e+-e- colliders to be linearLEP (<207 GeV COM) is last of breedConsider muons?
Large (!) circular machines for hadronsScaling in size/cost
Approaching unitary limitsFew 104 m in dimensionFew $109
Synchrotron radiation power lossForces future e+-e- colliders to be linear
LEP (<207 GeV COM) is last of breedConsider muons?
Large (!) circular machines for hadronsScaling in size/cost
Approaching unitary limitsFew 104 m in dimensionFew $109
Ps ∝γ 4
R2
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Tevatron complex at FNAL
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27 km circumference
SUSY 2006
Meeting the energy challengeMeeting the energy challenge
Avoid giantismCost above all
Higher fields give physics challenges
Circular machines: magnetsLinacs: accelerating fields
Enter new world of high energy density (HED) physics
Impacts luminosity challenge…
Avoid giantismCost above all
Higher fields give physics challenges
Circular machines: magnetsLinacs: accelerating fields
Enter new world of high energy density (HED) physics
Impacts luminosity challenge…
SUSY 2006
HED in future colliders I: the accelerator
HED in future colliders I: the accelerator
z
d
Linear accelerator schematicHigh fields in violent accelerating systems
Relativistic oscillations…Diseases
Breakdown, dark currentPeak power, heating
ApproachesHigh frequency, normal cond.SuperconductingLasers and/or plasma waves!
High fields in violent accelerating systems
Relativistic oscillations…Diseases
Breakdown, dark currentPeak power, heating
ApproachesHigh frequency, normal cond.SuperconductingLasers and/or plasma waves!
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eE z /mcω ~ 1
SUSY 2006
The Luminosity ChallengeThe Luminosity Challenge
Event rate = Lσ c
Luminosity : L =
Ne+Ne− fc
4πσ xσ y
=γNe+Ne− fc
4π βx*βy
* ⋅ εx,nεy,n
Circular colliders provide high repetition rateLinear colliders have much lower repetition rate
Use large N, small σ; very large collective beam fields
Inherent scaling for higher energy not enough:Must have very small phase space, focus well…“Moore’s law” also for luminosity; precision beams
Circular colliders provide high repetition rateLinear colliders have much lower repetition rate
Use large N, small σ; very large collective beam fields
Inherent scaling for higher energy not enough:Must have very small phase space, focus well…“Moore’s law” also for luminosity; precision beams
σ c ∝γ−2
SUSY 2006
HED in future colliders II: collective effects
HED in future colliders II: collective effects
Wakefields in linacs; limit on beam current and stabilityHuge collective fields in collision; luminosity limitLinear colliders:
Disruption (cold beams meet HED)“Beamstrahlung”; energy loss/spread, nuisance particlesClassical electrodynamics and quantum processesLC initial state not so “clean”
Wakefields in linacs; limit on beam current and stabilityHuge collective fields in collision; luminosity limitLinear colliders:
Disruption (cold beams meet HED)“Beamstrahlung”; energy loss/spread, nuisance particlesClassical electrodynamics and quantum processesLC initial state not so “clean”
F⊥,max ≈Nbe
2
σ zσ z
≈ 4 TeV/m in LC collision!
0 2Ub
SUSY 2006
Approaches to new collider paradigmsApproaches to new collider paradigms
Advancement of existing techniquesHigher field (SC) magnets (VLHC)Use of more exotic colliding particles (muons)Higher gradient RF cavities (X-band LC)Superconducting RF cavities (TESLA LC)
Revolutionary new approaches (high gradient frontier)
New sources: i.e., lasersNew structures and/or media: i.e., plasmas
Truly immersed in high energy density physics
Advancement of existing techniquesHigher field (SC) magnets (VLHC)Use of more exotic colliding particles (muons)Higher gradient RF cavities (X-band LC)Superconducting RF cavities (TESLA LC)
Revolutionary new approaches (high gradient frontier)
New sources: i.e., lasersNew structures and/or media: i.e., plasmas
Truly immersed in high energy density physics
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Cryostat with 16 T Nb3Sn magnet at LBNL
Muon collider schematic (R. Johnson, 2005)
2.5 km Linear Collider Segment
2.5 km Linear Collider Segment
µ +← postcoolers/preaccelerators µ− →
5 TeV µ µ+ − Collider 1 km radius, <L>~5E34
10 arcs separated vertically in one tunnel
HCC
300kW proton d i
Tgt
IRIR
Another Talk
SUSY 2006
The road to the next acceleratorThe road to the next acceleratorFirst fork in the road: Snowmass 2001
Consensus that ILC is next machine post-LHCVLHC and muons deferred…
Second fork: ITRP Selection of Linear Collider TechnologyBarish committee evaluates “warm” v. “cold” accelerator technology
First fork in the road: Snowmass 2001Consensus that ILC is next machine post-LHCVLHC and muons deferred…
Second fork: ITRP Selection of Linear Collider TechnologyBarish committee evaluates “warm” v. “cold” accelerator technology
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Superconducting option chosenSuperconducting option chosen
The crystal ball clears due to ITRP decision, 2004
SUSY 2006
The LC technology selectionThe LC technology selection
X-band, “high” gradient, normal conducting traveling wave linac
Superconducting, L-bandstanding wave cavity
• Superconducting option provides most robust path to ILC • Approach mitigates collective issues… try to avoid high energydensity…
SUSY 2006
Are we on the road to a 3 TeV LC?Are we on the road to a 3 TeV LC?
Surprise? SC LC option does not scale wellIntrinsic low gradient
24 MV/m TESLA 500 GeV 35 MV/m TESLA 800 GeV
Theoretical limit close
X-band still difficultPower sources, efficiencies
The linear accelerator paradigm is stressed to limit
Surprise? SC LC option does not scale wellIntrinsic low gradient
24 MV/m TESLA 500 GeV 35 MV/m TESLA 800 GeV
Theoretical limit close
X-band still difficultPower sources, efficiencies
The linear accelerator paradigm is stressed to limit
SUSY 2006
Paths to higher acceleration fieldsPaths to higher acceleration fieldsHigh field means high frequency
Where is power source?Look to wakefields
Coherent radiation from bunched, relativistic e- beamAlso powers more exotic schemes Intense beams needed by other fields (e.g. X-ray FEL)
What about lasers? Many TW of peak powerNeed to reinvent accelerator “structure”
Operate at small length scalesTolerate (or embrace) high energy density
High field means high frequencyWhere is power source?
Look to wakefields Coherent radiation from bunched, relativistic e- beamAlso powers more exotic schemes Intense beams needed by other fields (e.g. X-ray FEL)
What about lasers? Many TW of peak powerNeed to reinvent accelerator “structure”
Operate at small length scalesTolerate (or embrace) high energy density
SUSY 2006
High gradients, high frequency, EM power from wakefields: CLIC @ CERNHigh gradients, high frequency, EM
power from wakefields: CLIC @ CERNCLIC wakefield-powered scheme
CLIC 30 GHz, 150 MV/m structures
CLIC drive beam extraction structure Power
SUSY 2006
The optical acceleratorThe optical accelerator
Scale the linac from 1-10 cm µwave to 1-10 µm laser!Resonant structure (like linac)Slab symmetry (unlike linac)
Have copious powerAllows high beam charge Suppresses wakefields
Limit on gradient? 1-2 GV/m, avalanche ionization
Experiments SLAC (1 µm) 10 µm active media at BNL (PASER!)
Scale the linac from 1-10 cm µwave to 1-10 µm laser!Resonant structure (like linac)Slab symmetry (unlike linac)
Have copious powerAllows high beam charge Suppresses wakefields
Limit on gradient? 1-2 GV/m, avalanche ionization
Experiments SLAC (1 µm) 10 µm active media at BNL (PASER!)
Resonant dielectric structure schematic
Simulated fieldprofile (OOPIC);
half structure
e-beam
Laser power input
SUSY 2006
Evading material breakdown:The inverse FEL accelerator
Evading material breakdown:The inverse FEL accelerator
Run FEL backwards w/high power laserNo nearby material; laser field v. high
Magnetic field <=> synchrotron rad.
Acceleration dynamics like ion linacExperiment at UCLA Neptune Lab 15 MeV beam accelerated to over 35 MeV
Higher harmonic interaction observedBeam captured into “beamlets”
IFEL is now workhorse microbuncher
Run FEL backwards w/high power laserNo nearby material; laser field v. high
Magnetic field <=> synchrotron rad.
Acceleration dynamics like ion linacExperiment at UCLA Neptune Lab 15 MeV beam accelerated to over 35 MeV
Higher harmonic interaction observedBeam captured into “beamlets”
IFEL is now workhorse microbuncher
IFEL undulator (50 cm length)
Neptune IFEL single shot energy spectrum
SUSY 2006
Inverse Cerenkov AccelerationInverse Cerenkov AccelerationCoherent Cerenkov wakes can be extremely strong
Short beam, small aperture
SLAC FFTB, Nb=3E10, σz= 20 µm, a=50 µm, > 11 GV/m!Not optical — THz (unique source)
Coherent Cerenkov wakes can be extremely strongShort beam, small aperture
SLAC FFTB, Nb=3E10, σz= 20 µm, a=50 µm, > 11 GV/m!Not optical — THz (unique source)
eEzdec ≅ −2Nbremec
2
2πσ zaε −1ε
Simulated GV/m Cerenkov wakes for typical FFTB parameters (OOPIC -)
dielectric
vacuum
SUSY 2006
FFTB Cerenkov Wake ResultsFFTB Cerenkov Wake Results
UCLA/SLAC/LLNL expt. (2005)Quartz fibers
350 µm OD, 100-200 µm ID, 1 cm length
Observed breakdown threshold4 GV/m surface field 2 GV/m acceleration field!
Vaporization of Al cladding…dielectric more robust
UCLA/SLAC/LLNL expt. (2005)Quartz fibers
350 µm OD, 100-200 µm ID, 1 cm length
Observed breakdown threshold4 GV/m surface field 2 GV/m acceleration field!
Vaporization of Al cladding…dielectric more robust
View end of dielectric tube; frames sorted by increasing peak currentView end of dielectric tube; frames sorted by increasing peak current
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SUSY 2006
Past the breakdown limit:Plasma Accelerators
Past the breakdown limit:Plasma Accelerators
Very high energy density laser or electron beam excites plasma waves as it propagates
Excitation by ponderomotive forces (laser) or space-charge (beam) Extremely high fields possible:
Very high energy density laser or electron beam excites plasma waves as it propagates
Excitation by ponderomotive forces (laser) or space-charge (beam) Extremely high fields possible: E(V/cm) ∝ ne (cm-3)
Schematic of laser wakefieldAccelerator (LWFA)
E ∝100 GV/m, for ne =1018cm-3Ex: tenous gas density
SUSY 2006
Plasma Wakefield Acceleration (PWFA)Plasma Wakefield Acceleration (PWFA)
Electron beam shock-excites plasmaSame scaling as Cerenkov wakes Beam denser than plasma; nonlinear plasma wavesLinear wakefield response
Ez constant in r , Focusing linear in rFamiliar: like linac + quadrupoles
Electron beam shock-excites plasmaSame scaling as Cerenkov wakes Beam denser than plasma; nonlinear plasma wavesLinear wakefield response
Ez constant in r , Focusing linear in rFamiliar: like linac + quadrupoles
E ∝ Nbkp2 ∝ Nbσ z
−2
SUSY 2006
Ultra-high gradient PWFA: E164 experiment at SLAC FFTB
Ultra-high gradient PWFA: E164 experiment at SLAC FFTB
M. Hogan, et al.
ne=2.5x10 17 cm-3
plasma
New data, hoping for PRL cover
Uses ultra-short beam (20 µm) Beam causes field ionization
to create dense plasma (HED)Over 4 GeV(!) energy gain over 10 cm: >40 GV/m fieldsSelf-injection of plasma e-
On to energy doubling…
New experiments: >40 GeV in 90 cm plasma (E167)
SUSY 2006
Plasma wave excitation with laser: creation of very high quality beamPlasma wave excitation with laser: creation of very high quality beam
Trapped plasma electrons in LWFA give εn~1 mm-mrad at Nb>1010
Narrow energy spreads produced accelerating in plasma channels
Not every shot (yet)
Looks like a beam. Now >1 GeV!Other applications (FEL)Very popular
Lasers cost few $M
Trapped plasma electrons in LWFA give εn~1 mm-mrad at Nb>1010
Narrow energy spreads produced accelerating in plasma channels
Not every shot (yet)
Looks like a beam. Now >1 GeV!Other applications (FEL)Very popular
Lasers cost few $M
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SUSY 2006
Application: energy doubling of LC beams — the PWFA Afterburner Concept
Application: energy doubling of LC beams — the PWFA Afterburner Concept
SUSY 2006
Addressing the luminosity problem: Final focus plasma lenses
Addressing the luminosity problem: Final focus plasma lenses
Ions
E-Beam
Electrons
Magnetic Quadrupoles
UnderdensePlasma Lens
′ B ≈ 250 T/m ′ B equiv . = 3 × 10 −11 n p (T/m)Ex: superconducting quad strength
Linear collider densities give >107 T/mLow aberrations and short focal lengthLinear collider densities give >107 T/mLow aberrations and short focal length
Courte
sy J
BR
Uses electrostatic forces to focus electron beam in both dimensions.
Uses magnetic forces to focus electron beam in one dimension at a time.
Plasma lens strength
SUSY 2006
UCLA/FNAL Underdense Plasma Lens Expt.
Plasma focused – 1 pulse
Beam Spot Before: x FWHM = 1200 µmy FWHM = 1100 µm nb = 5 x 1012 cm-3
Beam Spot After (Ave.): x FWHM = 200 µmy FWHM = 300 µm nb = 1 x 1014 cm-3 Focused – 1 electron pulsesUnfocused – 5 electron pulses
The beam area is reduced by a factor of 22. Equivalent to luminosity enhancement
SUSY 2006
Prospects for advanced accelerators in HEPProspects for advanced accelerators in HEP
Optical/plasma accelerators challengingVery large fieldsVery small dimensions and time scalesMultidisciplinary in the extreme
Many collective effects to worry about Can we achieve precision HEP beams in presence of HED?
Still orders of magnitude in learning curveBreath-taking recent progressMore people needed; students eager/welcome
Optical/plasma accelerators challengingVery large fieldsVery small dimensions and time scalesMultidisciplinary in the extreme
Many collective effects to worry about Can we achieve precision HEP beams in presence of HED?
Still orders of magnitude in learning curveBreath-taking recent progressMore people needed; students eager/welcome
SUSY 2006
Marx HEPAP Subpanel SupportMarx HEPAP Subpanel Support
Increased in investment in accelerator scienceSpecial concern for long-range researchIncreased in investment in accelerator scienceSpecial concern for long-range research
A major challenge for the accelerator science community is to identify and develop new concepts for future energy frontier accelerators that will be able to provide the exploration tools needed for HEP within a feasible cost to society. The future of accelerator-based HEP will be limited unless new ideas and new accelerator directions are developed to address the demands of beam energy and luminosity …
A major challenge for the accelerator science community is to identify and develop new concepts for future energy frontier accelerators that will be able to provide the exploration tools needed for HEP within a feasible cost to society. The future of accelerator-based HEP will be limited unless new ideas and new accelerator directions are developed to address the demands of beam energy and luminosity …