SABER SCIENCE

FFTB has Produced Spectacular Science

SABER will continue this tradition

EPAC 24 Jan.2006, C. Joshi-UCLA

U C L A

What is SABER Facility?

South Arc Beam Experimental RegionSABER is a high energy electron and positron beam line intended as a replacement for FFTB.

FFTB SABERParticles e+ e- e+ e- Charge 3nC 3nCBunch Length e- 30 fs (SPPS Chicane e+

e+ 2 ps e-, < 100 fsFocused spot size 5-10 µm 10 µm

Parasitic to PEP SABER AND LCLS independent

Where is SABER?

Bypass of linac sectors 20-30 forIndependent operation of SABER and

LCLSSee presentation by Roger Erickson

70 m long straight section of south arc of the SLC

Positron and electron cmpressors

SABER Timeline• July,2005 Persis Drell asks R. Siemann and

C. Joshi to prepare SABER SCIENCE case

• Sept. 19, 2005 One day workshop held at SLAC to identify major research areas. Draft white paper

prepared and sent to Persis Drell.

• Oct. 2005 White paper submitted to DOE-HEP

• Mar. 2006 Full blown SABER Science Workshop at SLAC to involve greater scientific

community

Major Scientific Topics Identified for SABER Science

1. Advanced Acceleration Techniques: (E157, 162, 164, 164X, E167, E150)

2. Laboratory Astrophysics (E165,T140)

3. Inverse Compton Scattering Source

4. THz Surface Chemistry

5. Magnetization Dynamics and Solid State Physics

1)AdvancedAccelerationTechniquesC.Clayton,M.Hogan,C.Joshi,T.Katsouleas,W.Mori,P.Muggli,R.Siemann

• Strong existing collaboration: UCLA/USC/SLAC-ARDB Groups on Plasma Wakefield Acceleration (PWFA)

• E150 experiment showed positron focusing by a thin plasma lens, J. Ng et al., PRL

• Strong desire to develop the PWFA scheme as an energy/gradient doubler for a linear collider?

E164x data2005

E164X August Run14GeV Energy Gain in less than 30cm !

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� Double the energy of Collider w/ short plasma sections before IP

� 1st half of beam excites wake --decelerates to 0� 2nd half of beams rides wake--accelerates to 2 x

Eo

� Make up for Luminosity decrease N2/z2 by halving

in a final plasma lens

50 GeV50 GeV ee--

50 GeV50 GeV e e++e-WFA e+WFA

IP

LENSES

7m

PLASMA AFTERBURNER

S. Lee et al., PRST-AB (2001)U C L AP. Muggli

GRAND CHALLENGE in AAC

Afterburner simulationMinimal hosing!

1) Matched wedge shape drive beam with trailing bi-Gaussian beam.

2) Background plasma density.

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New FAST 3-D Quasi-static PIC Model (QuickPIC)

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50 GeV energy gain in 3 meters !

Accelerating field24GeV/m at the load

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PLASMA AFTERBURNER PROOF OF PRINCIPLE

WAKEFIELD FIELDS for e- & e+

e- e+

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

-15 -10 -5 0 5 10 15

ElectronFieldsChenKun.kg

τ ( )ps

0

100

200

300

-15 -10 -5 0 5 10 15

PositonFieldsChenKun.kg

τ ( )ps

• Blow-Out• Accelerating “Spike”

• Fields vary along r, stronger

• Less Acceleration

ne=1.51014 cm-3

homogeneous, QUICKPIC

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Short e+ pulses from SABER will allow gradients to go from 60 MeV/m (FFTB) to 5 GeV/m

Previous Results

B. Blue et al. (E162)Phys. Rev. Lett.

SABER Parameters

5.7GeV in 39cm

Plasma Focusing to Submicron-Spot Sizes

FFTB experiments have shown a factor 2 decrease in positron beam sizes using plasma lenses.

Can we focus e+,e- SABER beams to submicron dimension using plasma lenses? Can we design layered structures as lenses for obtaining nanometer spot sizes?

0

50

100

150

200

0 5 10 15 20 25

Positron(ne)c-g.kg

ne (×1012 cm-3)

M.Hogan et.al. PRL 03

2) Laboratory Astrophysics

FLASH(E165) and T140 on FFTB

Johnny S.T. Ng

Stanford Linear Accelerator Center, Stanford University

Members of LabAstro Working Group:

R. Bingham, P. Chen, P. W-Y Hwang, G-L Lin, R. Noble, K. Reil, R. Sydora

SLAC, Sep. 19, 2005

LabAstro Program at SABER

• Testing and Calibration of UHECR Observational techniques– Such as FLASH and T460 at FFTB

• Investigation of jet-plasma dynamics to elucidate the underlying physics of cosmic acceleration– SABER is unique: 1016 J/m3 beams

– Extreme relativistic plasma jets accessible in a terrestrial environment for the first time!

1. Cline (UCLA): Primordial Black Hole Induced Plasma Instability Expt.

2. Sokolsky (Utah): High Energy Shower Expt. for UHECR FLASH Exp. (E165)

3. Kirkby (CERN): CLOUD Expt. on Climate Variation 4. Chen-Tajima (SLAC-Austin): 4. Chen-Tajima (SLAC-Austin): Ponderomotive Acceleration Expt. for UHECR and BlazarsPonderomotive Acceleration Expt. for UHECR and Blazars 5. Nakajima (KEK): Laser Driven Dirac Acceleration for UHECR Expt. 6. Odian (SLAC): Non-Askaryan Effect Expt. 7. Rosner (Chicago): Astro Fluid Dynamics Computer Code Validation

Expt. 8. Colgate-Li (LANL): Magnetic Flux Transport and Acceleration Expt. 9. Kamae (SLAC): Photon Collider for Cold e+e– Plasma Expt.10. Begelman-Marshall (CO-MIT): X-Ray Iron Spectroscopy and Polarization Effects Expt.11. Ng (SLAC): 11. Ng (SLAC): Relativistic eRelativistic e++ee– – Plasma Expt. Plasma Expt.12. Katsouleas (USC): Beam-Plasma Interaction Induced Photon Burst Expt.13. Blandford (CalTech): 13. Blandford (CalTech): Beam-Plasma Filamentation Instability Expt.Beam-Plasma Filamentation Instability Expt.

14. Scargle (NASA-Ames): Relativistic MHD Landau Damping Expt.

Pisin Chen (10-22-01)

Possible Laboratory Astrophysics Experiments

Suggested in Oct. 2001 Workshop on Laboratory Astrophysics at SLAC:

Cosmic Acceleration at SABER

• Create relativistic electron-positron plasma “jets” by showering in solid target

• Investigate jet-plasma dynamics over a scale of tens of collisionless skin-depths

• Current simulation techniques can accurately resolve physics on this scale

Applicable to astronomical collisionless plasmas

Important tests of our ability to simulate theseeffects in astronomical environments

Acceleration in Relativistic

Jet-Plasma Interactions

High-energy-density beam

Solid targetElectron-positron plasma jet (10-100 MeV)

Jet-plasma interaction:• Inductive acceleration• Wakefield acceleration

Particle and radiation detectors

Simulation Results: Overview

1. Transverse dynamics (same for continuous and short jets): Magnetic filamentation instability: inductive Ez Positron acceleration; electron deceleration

2. Longitudinal dynamics (finite-length jet): Electrostatic “wakefield” generation Persists after jet passes: acceleration over long distances.

Particle Acceleration and Deceleration

Longitudinal momentum distribution of positrons and electrons for a finite-length jet at three simulation time epochs.

t in units of 1/p

~ 40% of positrons gained >50%In longitudinal momentum (pz)

Alfven-Shock Induced Plasma Wakefield Acceleration

(Chen, Tajima, and Takahashi, PRL, 2001)

• Generation of Alfven waves in relativistic plasma flow• Inducing high gradient nonlinear plasma wakefields• Acceleration and deceleration of trapped e+/e-

• Power-law (n ~ -2) spectrum due to stochastic acceleration

High Gradient WakefieldAcceleration in a Relativistic Plasma

Undulator

e+e–e–

e+

1 m

B0

Spectrometer

Bu

Solenoid

Beam

Summary

SABER is unique: high-energy-density beams providing relativistic plasma jets

“To understand the acceleration mechanisms of these [UHECR] particles, a better understanding of relativistic plasmas is needed”

“Laboratory work [thus] will help to guide the development of a theory of cosmic accelerators, as well as to refine our understanding of other astrophysical phenomena that involve relativistic plasmas.”

Turner Committee on the Physics of the Universe: “Eleven Science Questions For the New Century”, NRC, 2003

3)Coherent Control of Surface Reactions

using THz Radiation @SABER

Hirohito Ogasawara, D. Nordlun & A.Nilsson

•80% of all important chemical reactions 80% of all important chemical reactions take place on interfacestake place on interfaces

•Catalysis is arguably the most important Catalysis is arguably the most important process in the chemical industry:e.g. process in the chemical industry:e.g. Ammonia production on iron Ammonia production on iron

•Breaking and formation of bonds on fs Breaking and formation of bonds on fs timescaletimescale

• Energies are O(kT)Energies are O(kT)

•Need a 100fs long THz source synched with Need a 100fs long THz source synched with an X-ray probe beaman X-ray probe beam

THz radiation and molecular vibration

THz = Far-IR (~0.01[eV], ~30[m]) can excite thermal process: lattice vibration, adsorbate-metal vibration.

Black body radiation at ambient temperature

lattice vibration Metal-physisorbate vibration metal-chemisorbate vibration

Temperature jump viaElectron-hole pair

excitation, Lattice vibration

excitation,….required power: ~1-10 mJ/pulse

THz radiation and surface chemistryTemperature jump

Temperature jump ensues the motion of adsorbate and stimulates surface chemical reactions.

fs laser: hot electron problem

THz: NO hot electron

Temperature jump viaElectron-hole pair

excitation, Lattice vibration

excitation,….required power: ~1-10 mJ/pulse

Temperature jump

Temperature jump ensues the motion of adsorbate and stimulates surface chemical reactions.

e-beam bunch length

1) wavelength < bunch length ….. incoherent radiation

2) wavelength > bunch length …. coherent radiation

Ultra short electron bunch is necessary for coherent THz radiation.Bunch length = high frequency cut-off

5-10mm ~20mSpectrum

100fs pulse~ps pulse

CSR

THz E-field and surface chemistry

THz electric field ~ Coulomb force between e- and the nuclei manipulation of molecule, coherent control molecular motion

strong electric field pulse

How to probe THz induced process

on-axis radiation, soft X-ray, hard X-ray, off-axis radiation: THzPump: THz, Probe: XPS, XES, XAS, XRD, IR

FEL can produce intense X-ray and THz radiation from the same electron bunch.

develop at SABER

Summary THz Surface Chemistry

•THz region = far IR ~ kT lattice vibration, adsorbate-substrate vibration•coherent radiation ~ 109 times more intense than incoherent radiation.•short electron bunch = high cut-off frequency•coherent broad band = electric field pulse unipolar Bunch length: <100fs, Charge: ~nC•coherent atom manipulation on surfaces

4) INVERSE COMPTON SCATTERING (ICS) Source at SABER

Sven Reiche(UCLA)

SLAC - 9/19/05

Radiation Source at SABER

• Electron beam cannot drive FEL , nor is sufficient space available

• Spontaneous undulator radiation only a minor improvement in wavelength, might compete with future energy upgrade of LCLS. In addition insufficient space for undulator, collimator and shielding

• Inverse Compton Scattering (ICS) requires only a drive laser with high energy per pulse (~ 1J). Short pulse and high power not necessary.

• Radiation benefits from small spot size and high beam energy.

Current ICS Sources

• Most ICS sources use beam energies in the 10 to 100 MeV range to operate in the keV photon energy range.

• Highest photon energy at Spring8 storage ring– Electron beam energy 8 GeV– Photon energy: 1.5 - 2.4 GeV (no tunability by electron energy)

– 1 mm electron beam size, 100 mA current– No high rep rate to avoid reduction in life-time of stored electrons

– Operates as user facility.

Scientific Opportunities

• Studies for - colliders• Gamma source for detector development (calorimeter)

• Nuclear spectroscopy• Gamma induced fission (e.g. meta-stable states of U238)

• Quantum fluctuation dominated emission process (spectral properties etc.)

• Probing the nucleus:Spin Sum Rule

Scientific Case - Baryonic/Hadronic

Physics• Excitation of baryonic states of nucleons

• Threshold productions of mesons, e.g. 2 production

• K-meson production, parity measurement.

Schematic Layout of ICS Source

Ti:Saph Laser Laser Transport

Interaction Region

Final FocusShielding

To Users

Movable Mirrors

Expected Performance

• Wavelength Range:

€

h =2γ 2 1−β cosφ( )hω0

1+ a2 /2 + γ 2θ 2

Normalized field a should be < 0.1 to reduce red shift and improve spectral brightness

Lowest energy20 - 250 MeV10º

Shortest pulses0.25 - 3 GeV45º

Highest energy2.5 - 30 GeV180ºCommentsPhoton Energy*Incident Angle

* Electron Beam Energy : 10 - 37 GeV

Estimate for Photon Numbers

• Photon count (Thomson scattering)

• ICS requires rather large pulse energy than high power.

• High intensities should be avoided (a > 1) to exclude non-linear broadening of the spectrum

• Due to high electron energy quantum effects (recoil of Compton scattering) blow up of electron energy spread can be expected.

€

Nγ =σL =8π

3re

2 NLNe4πσ x

2=1.2 ⋅109 ⋅U[J]⋅Q[nQ]

5) Magnetism and Solid State Physics at SABER

H.C.Siegmann,C.Stamm and

J.Stohr

SSRL

C.Stamm et.al. PRL (2005)

Magnetism and Solid State Physics on SABER• Intense electric and magnetic fields associated with intense electron bunches:1e10 V/m and 100 T.

• Fields are quasi DC• Can be used to study ultra-fast magnetization dynamics and response of materials to ultra-fast non-oscillating electric fields.

Ultrafast Magnetization DynamicsMagnetic recording requires ever smaller bits and faster magnetic switching

FFTB experiments showed the processional switching mode

Switching time shown to be o(1ps) with magnetic field pulses applied perpendicular to magnetization(traditionally B anti-parallel to M and switching time o(1nS).

Magnetization Dynamics on SABER

• Ultra-short SABER electron pulses will deposit a large amount of angular momentum into the spin system leading to non-equilibrium position of the magnetization.

• Study of subsequent relaxation into one of the equilibrium states possible.

Solid State physics on SABER

• The electrical fields associated with SABER bunches can be used to excite surface plasmons in non-magnetic metal samples.

• The dynamics could be studied by probing the sample with laser pulses and measuring the photoelectron yield or changes in reflectivity.

UCOP Science and Technology Forum –

emerging opportunitiesUltrafast Science

• Ultrafast Science implies the ability to capture, in real time, the most fundamental processes in materials

• Ultrafast Science is a common interest of the Campuses and Labs

HEDS/LCLS Advanced Accelerators(AA)

• UC and collaborators are world leaders in AA research.

• Laser and beam-driven plasma accelerators are

producing compact accelerators that can generate radiation from mm wave to gamma ray range.

• The region encompassed by the University of California is rich with state of the art computational and experimental capabilities

• The proposed HEDS end station at LCLS provides new opportunities in HEDS research

UC Alliance in Advanced Accelerator Research (AAR)

Why?: To ensure UC leadership in AR and its applications

How?: Support these three activities.

a) High Energy e+,e- beam line (SABER) at SLACb) Petawatt class laser at LBNLc) 2000 node, cluster for AAR simulations at UCLA

CONCLUSIONS

• Opportunities at SABER in Accelerator Physics, Laboratory Astrophysics, Surface Chemistry, Magnetism and Solid-State and Nuclear Physics have been identified.

• Workshop in March will be the beginning of a process to develop a strong user community for SABER.

• SABER Science will undoubtedly produce groundbreaking physics SLAC is known for.