Plans for a VUV Science Program at the FEL
Gwyn P. Williams
Free Electron Laser
Jefferson Lab
12000 Jefferson Avenue
Newport News, Virginia 23606
JSA Science Council January 7, 2011
Slide 1/25
Outline
• Context
• Strategy
• Detailed experimental plan
Slide 2/25
Average Brightness
(photons/sec/mm2/mrad2)
JLab FEL
4th Generation
3rd Generation
2nd Generation
Photon Energy (eV)
Slide 3/25
Average Brightness Landscape for Light Sources
ANL-08/39
BNL-81895-2008
LBNL-1090E-2009
SLAC-R-917
Ultimate
light source
JLAB
upgrade
NGLS
JLAB upgrade
harmonics
Slide 4/25
Average Brightness
(photons/sec/mm2/mrad2)
JLab FEL VUV Opportunities
VUV Ops Target
Work
function
of metals
Table-top
laser limit
Photon Energy (eV)
Slide 5/25
Real Numbers
- above table is for 10 eV photon energy, 0.1% bandwidth
- assumes JLab FEL at 4.7 MHz, 230 fs FWHM
Slide 6/25
Real Numbers – more detail
•
•
•
Advanced light source average brightness
HGHG average brightness
Jefferson Lab FEL average brightness
= 1.0 × 1017
= 4.1 × 1013
= 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.
Slide 7/25
Strategy
•
•
•
•
•
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
Slide 8/25
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
Slide 9/25
Atom Trap Trace Analysis (ATTA)
PI -
Lu Zheng-Tian – Argonne National Lab
Charles 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.
Slide 10/25
Slide 11/25
Atom Trap Trace Analysis (ATTA)
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
Slide 12/25
Slide 13/25
Chemical Dynamics
PI - David Osborne – Sandia (West) National Lab
Craig Taatjes (Sandia), Steve Leone (LBNL)
Science – new insight into chemistry by identification of reactionintermediates 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
Slide 14/25
Isomeric composition
is important
+ O2  CO2 + H2O
+ O2  CO2 + H2O
+ R  PAH
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Chemical Dynamics
C3H3 + C2H2 → C5H5 + C2H2
→ C7H7 . . .
Intensity
C3H3
mass 39
mass 65
mass 91
mass 116
C5H5
C7H7
C9H8
0
20
40
60
Time (ms)
80
100
Reaction studied as function of time
Courtesy Taatjes group, Sandia
Slide 19/25
Slide 20/25
Electronic Structure of Correlated Materials
PI -
Peter Johnson – Brookhaven National Lab
Z.-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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Photoemission of Correlated Materials
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)]
Slide 22/25
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.
Slide 24/25
The Jefferson Lab FEL Team
April 24, 2009
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
Slide 25/25
Vision Lab, and by DOE Basic Energy & Nuclear Sciences under contract DE-AC05-