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Gwyn P. WilliamsFree Electron Laser

Jefferson Lab12000 Jefferson Avenue

Newport News, Virginia 23606

JSA Science Council January 7, 2011

Plans for a VUV Science Program at the FEL

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Outline

• Context

• Strategy

• Detailed experimental plan

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Avera

ge B

righ

tness

(photo

ns/

sec/

mm

2/

mra

d2

)

Photon Energy (eV)

2nd Generation

3rd Generation

4th Generation

JLab THz

JLab

FEL

JLab FEL

potential

upgrade

path

harmoni

cs

JLab FEL

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ANL-08/39BNL-81895-2008

LBNL-1090E-2009SLAC-R-917

JLABupgrade

LCLSJLAB upgrade harmonics

NGLS

FLASH

Ultimatelight source

Average Brightness Landscape for Light Sources

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Avera

ge B

righ

tness

(photo

ns/

sec/

mm

2/

mra

d2

)

Photon Energy (eV)

JLab THz

JLab

FEL

JLab FEL

potential

upgrade

path

harmoni

cs

Work function

of metals

Table-top laser

limit

VUV Ops Target

JLab FEL VUV Opportunities

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Real Numbers

- above table is for 10 eV photon energy, 0.1% bandwidth- assumes JLab FEL at 4.7 MHz, 230 fs FWHM

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Real Numbers – more detail

• Advanced light source average brightness = 1.0 × 1017

• HGHG average brightness = 4.1 × 1013

• Jefferson Lab FEL average brightness = 7.5 × 1018

Jefferson Lab appears to have an advantage of 75, but the ALS requires a monochromator, which has a transmission of 10% at most.

Jefferson Lab could also increase repetition rate by factor of 16 with cryo-cooling of the optics.

So – potential gain of JLab FEL in near-future could be 3-4 orders of magnitude.

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• Focus on new physics for which FEL is game-changing

• Engage with stakeholders – BES and our Science Advisory Board

• Try to engage local or SURA universities

• Select 3 experiments in both materials and atomic science

• Collaborate with groups experienced in light source work

• Use existing equipment, don’t be over ambitious

• It is important to measure the bandwidth of our beam

Strategy

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Initial Science with JLab VUV FEL

1. Atom Trap Trace Analysis (ATTA). Lu Zheng-Tian (ANL)

- nuclear physics funded

2. Combustion dynamics. David Osborn (Sandia)

- recommended by Eric Rohlfing, BES

3. Electronic structure of correlated materials.Peter Johnson (BNL), Z.-X. Shen (Stanford)

- co-recipients of 2011 Buckley prize

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Atom Trap Trace Analysis (ATTA)

PI - Lu Zheng-Tian – Argonne National LabCharles Sukenik – Old Dominion University

Science – develop Kr dating.

81Kr clock is 229,000 yrs compared to C, which is 5730 yrs

Qualifications – experiment running at Argonne.

Critical application – dating the polar ice-caps.

Why FEL? – high average power can study small volumes of water.

Advantage of the experiment is that it uses FEL direct beam, without need of monochromator. The sample automatically selects the bandwidth it needs.

Implementation - Idea is to bring equipment from Argonne, and collaborate with local university user.

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Schematic layout of the krypton ATTA apparatus. Metastable krypton atoms are produced in the discharge. The atoms are then transversely cooled, slowed and trapped by the laser beams shown as solid arrows. The fluorescence of individual trapped atoms is imaged to a detector. Total length of the apparatus is about 2.5 m

Courtesy Lu Zheng-Tian ANL

Atom Trap Trace Analysis (ATTA)

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Chemical Dynamics

PI - David Osborne – Sandia (West) National Lab Craig Taatjes (Sandia), Steve Leone (LBNL)

Science – new insight into chemistry by identification of reaction-intermediates using selective ionization then capture – isomeric detection is critical and new.

Qualifications: Currently running experiments at the ALS, Berkeley.

Critical Application - advanced complex fuels, new engines and pollution control.

Why FEL? – enables low cross-section species to be studied.

Advantage of the experiment is that it may be able to use FEL direct beam, without need of monochromator. The sample automatically selects the bandwidth it needs.

Implementation - bring equipment from Sandia/Berkeley

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Isomeric compositionis important

+ O2 CO2 + H2O

+ O2 CO2 + H2O+ R PAH

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Inte

nsity

100806040200Time (ms)

mass 39 mass 65 mass 91 mass 116

C3H3

C5H5

C7H7

C9H8

Chemical Dynamics

Reaction studied as function of time

C3H3 + C2H2 → C5H5 + C2H2

→ C7H7 . . .

Courtesy Taatjes group, Sandia

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Electronic Structure of Correlated Materials

PI - Peter Johnson – Brookhaven National LabZ.-X. Shen – Stanford University/ALS Berkeley

Science – measure electron quantum structure via photoemission.

Qualifications – already running experiments at NSLS and ALS.

Critical application – understanding novel materials such as high Tc superconductors.

Why FEL? - Higher photon energies allow access to the whole Brillouin zone, not accessible at present. 2 photons also available for pump-probe. Short pulses for time of flight detector development.

NB - This experiment will require a monochromator, which when implemented will enable many more experiments.

Implementation - bring equipment from Brookhaven.

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Energy and momentum resolved snapshot of the electronic structure of the charge density wave system TbTe3 at a time-delay of 200 fs after photoexcitation.

F. Schmitt et al., Science 321, 1649 (2008)]

Photoemission of Correlated Materials

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Future Options

• The continuation of the experimental program using what we have is subject to operating funds. Building an extended program would require us to address reliability issues.

• Potential to increase photon flux by order of magnitude using cryo-cooled mirrors (500K).

• Proposal already in to BES for new injector, and some operations funds to study electron beam dynamics ($10M).

• Could engage with BES to try to get funds for re-furbished linac sections to take fundamental to 10 eV. Additional funds could take it to 100 eV.

• Pursuing the science program will require a new program advisory committee, and we might think of a science workshop.

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Conclusions

We continue to operate and characterize the VUV-FEL.

We are engaged with BES & several high profile users.

The present plans rely on our measured performance to date, with possibilities of considerable improvement.

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The Jefferson Lab FEL Team

This work supported by the Office of Naval Research, the Joint Technology Office, the Commonwealth of Virginia, the DOE Air Force Research

Laboratory, The US Army Night Vision Lab, and by DOE Basic Energy & Nuclear Sciences under contract DE-AC05-060R23177.

April 24, 2009