U C L A

SABER SCIENCE

FFTB has Produced Spectacular Science

SABER will continue this tradition

EPAC 24 Jan.2006, C. Joshi-UCLA

What is SABER Facility?

South Arc Beam Experimental Region

SABER is a high energy electron and positron beam line intended as a replacement for FFTB.

Particles Charge Bunch Length Focused spot size

FFTB

e + e 3nC e 30 fs (SPPS Chicane e + 2 ps 5-10 µm Parasitic to PEP

SABER

e + e 3nC e + e , < 100 fs 10 µm SABER AND LCLS independent

Where is SABER?

70 m long straight section of south arc of the SLC Positron and electron cmpressors Bypass of linac sectors 20-30 for Independent operation of SABER and LCLS

See presentation by Roger Erickson

• • • •

SABER Timeline

July,2005 Sept. 19, 2005 Oct. 2005 Mar. 2006 Persis Drell asks R. Siemann and C. Joshi to prepare SABER SCIENCE case One day workshop held at SLAC to identify major research areas.

Draft white paper prepared and sent to Persis Drell.

White paper submitted to DOE-HEP 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)AdvancedAccelerationTechniques

C.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 data

2005

E164X August Run

14GeV

Energy Gain in less than 30cm !

U C L A

GRAND CHALLENGE in AAC

P LASMA A FTERBURNER � � � � Double the energy of Collider w/ short plasma sections before IP 1 st half of beam excites wake --decelerates to 0 2 nd half of beams rides wake--accelerates to 2 x E o Make up for Luminosity decrease  N 2 /  z 2 by halving  plasma lens in a final 50 GeV e -

e WFA

LENSES

e + WFA

IP 7m 50 GeV e + S. Lee

et al.

, PRST-AB (2001)

U C L A

P. Muggli

Afterburner simulation

Minimal hosing!

U C L A

QuickTime™ and a MPEG-4 Video decompressor are needed to see this picture.

QuickTime™ and a MPEG-4 Video decompressor are needed to see this picture.

QuickTime™ and a MPEG-4 Video decompressor are needed to see this picture.

1)

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

New

FAST

2)

Background plasma density.

3-D Quasi-static PIC Model (QuickPIC)

PLASMA AFTERBURNER PROOF OF PRINCIPLE

50 GeV energy gain in 3 meters !

QuickTime™ and a MPEG-4 Video decompressor are needed to see this picture.

Accelerating field

24GeV/m at the load

U C L A

W AKEFIELD F IELDS for

e

&

e

+

U C L A

e e +

n e

=1.5

 10 14 cm -3 homogeneous, QUICKPIC 0.2

0.1

0 -0.1

-0.2

-0.3

-0.4

-15 -10 -5 0  (ps) 5 • Blow-Out • Accelerating “Spike” ElectronFieldsChenKun.kg

10 15 -15 • Fields vary along r, stronger • -10 -5 0  (ps) 5 Less Acceleration 300 200 100 PositonFieldsChenKun.kg

10 15 0

Short e

+

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

5.7GeV in 39cm

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

SABER Parameters

Plasma Focusing to Submicron-Spot Sizes

200 150 100 50

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

M.Hogan et.al. PRL 03 Po si tro n(ne )c-g .kg

0 0 5 10 15 n e (  10 12 cm -3 ) 20 25

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?

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: 10 16 J/m 3 beams Extreme relativistic plasma jets accessible in a terrestrial environment for the first time!

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

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): Ponderomotive 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): Relativistic e + e – Plasma Expt.

12. Katsouleas (USC): Beam-Plasma Interaction Induced Photon Burst Expt.

13. Blandford (CalTech): Beam-Plasma Filamentation Instability Expt.

14. Scargle (NASA-Ames): Relativistic MHD Landau Damping Expt. Pisin Chen (10-22-01)

• • •

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 these effects in astronomical environments

Solid target

Acceleration in Relativistic Jet-Plasma Interactions

Particle and radiation detectors Jet-plasma interaction: • Inductive acceleration • Wakefield acceleration Electron-positron plasma jet (10-100 MeV) High-energy-density beam

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/ w p ~ 40% of positrons gained >50% In longitudinal momentum (p z )

High Gradient Wakefield Acceleration in a Relativistic Plasma

Beam

e – Alfven-Shock Induced Plasma Wakefield Acceleration

(Chen, Tajima, and Takahashi, PRL, 2001) 1 m Solenoid

e + e + e –

B u B 0

Undulator Spectrometer • 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

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 take place on interfaces

•

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

•

Breaking and formation of bonds on fs timescale

•

Energies are O(kT)

•

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

THz radiation and molecular vibration

lattice vibration Metal-physisorbate vibration Black body radiation at ambient temperature metal-chemisorbate vibration

THz = Far-IR

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

THz radiation and surface chemistry Temperature jump

Temperature jump

via Electron-hole pair excitation, Lattice vibration excitation, ….

required power: ~1-10 mJ/pulse

fs laser: hot electron problem THz: NO hot electron Temperature jump ensues the motion of adsorbate and stimulates surface chemical reactions.

Temperature jump

Temperature jump

via Electron-hole pair excitation, Lattice vibration excitation, ….

required power: ~1-10 mJ/pulse

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 5-10mm ~ps pulse ~20 m m 100fs pulse Spectrum

CSR

Ultra short electron bunch is necessary for coherent THz radiation.

Bunch length =

high frequency

cut-off

THz E-field and surface chemistry

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

How to probe THz induced process

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

develop at SABER on-axis radiation, soft X-ray, hard X-ray, off-axis radiation: THz

Pump:

THz,

Probe:

XPS, XES, XAS, XRD, IR

Summary THz Surface Chemistry

•THz region = far IR ~ vibration •coherent radiation ~ 10

kT

lattice vibration, adsorbate-substrate 9 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

Laser Transport Ti:Saph Laser Movable Mirrors To Users Final Focus Interaction Region Shielding

Expected Performance

• Wavelength Range: w  2  2  1   cos   1 

a

2 w 0 /2   2  2 Normalized field a should be < 0.1 to reduce red shift and improve spectral brightness 

Incident Angle

180º 45º 10º

Photon Energy*

2.5 - 30 GeV 0.25 - 3 GeV 20 - 250 MeV

Comments

Highest energy Shortest pulses Lowest energy * Electron Beam Energy : 10 - 37 GeV

Estimate for Photon Numbers

• Photon count (Thomson scattering)

N

  

L

 8  3

r e

2

N L N e

4 

x

2  1.2

 10 9 

U

[

J

] 

Q

[

nQ

] • 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.

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 Dynamics

Magnetic 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 opportunities

HEDS/LCLS Ultrafast Science Advanced Accelerators(AA)

• •

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

• •

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 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.

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 SLAC b) Petawatt class laser at LBNL c) 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.