The Genesis of the LCLS

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The Genesis of the LCLS

• Herman Winick
• SLAC National Accelerator Laboratory
• Presented at
• ICFA Workshop on Future Light Sources (FLS2012)
• Newport News VA
• March 8, 2012

Draft Mar. 6, 2012 2pm
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The history of X-ray free-electron lasers. C.
Pellegrini, UCLA

• Dear Colleagues, Feb. 27, 2012
•  
• I am sending you a link to read or download a
  paper that I have recently written and is in
  course of publication in European Physical
  Journal H (EPJH, Historical perspective on
  Contemporary Physics).
•  
• The file is too large to be attached to this
  message because of the many figures. I hope you
  might find it interesting and welcome your
  comments.
•  
• files.me.com/claudiusmixcxxxv/qzap0j
  lthttps//files.me.com/claudiusmixcxxxv/qzap0jgt
•  
• Best regards
•  
• Claudio Pellegrini

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The history of X-ray free-electron lasers C.
Pellegrini, UCLA

• Abstract
•  
• The successful lasing at SLAC of LCLS, the first
  X-ray free-electron laser (X-FEL), in the
  wavelength range 1.5 to 15 Ångstrom, with pulse
  duration from 50 to a few femtoseconds, and a
  number of coherent photons per pulse ranging from
  1013 to 1011, is a landmark event in the
  development of coherent electromagnetic radiation
  sources. Until now the best X-ray source was
  provided by an electron beam traversing an
  undulator magnet in a storage ring, usually
  referred to as a synchrotron radiation source.
  The LCLS has set a new standard. Its X-ray
  brightness is higher than that of the best
  synchrotron radiation source by ten orders of
  magnitudes. For the first time, the X-ray beam
  generated by LCLS gives us the capability of
  exploring matter at the atomic and molecular
  level, with wavelength and pulse duration as
  short as the atomic scales of length and time.
  Creating matter from the vacuum, taking an atomic
  scale motion picture of a chemical process in a
  time of a few femtoseconds or less, and
  unraveling the structure and dynamics of complex
  molecular systems, like proteins, are some of the
  exciting experiments made possible by this novel
  X-ray source. LCLS, and the other X-ray FELs now
  being built in Europe and Asia, will open a new
  chapter in the biological and physical sciences.
  What has made this success possible, and what
  will be the likely future developments for X-ray
  FELs? In this paper, we describe the history of
  the many theoretical, experimental and
  technological discoveries and innovations,
  starting from the 1960s and 1970s, leading to the
  first X-ray FEL, and consider what can be the
  next steps in their developments.

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https//news.slac.stanford.edu/features/20th-anniv
ersary-great-idea-building-lcls-slac

• 20th Anniversary of a Great Idea Building the
  LCLS at SLAC
• February 23, 2012 by Herman Winick
• The spectacular success of the Linac Coherent
  Light Source (LCLS), the worlds first hard X-ray
  free-electron laser, has put SLAC National
  Accelerator Laboratory at the frontier of photon
  science. Although relevant work was done by many
  scientists 30 or more years ago, the idea for the
  LCLS at SLAC really got started 20 years ago this
  month, when 146 scientists from around the world
  gathered here in 1992  from Feb. 24 to Feb. 27
   for the Workshop on Fourth Generation Light
  Sources.
• At this workshop Claudio Pellegrini of the
  University of California-Los Angeles stood up to
  propose that a powerful new free-electron laser,
  operating in the previously unattainable short
  X-ray wavelength range of 4 nanometers to 0.1
  nanometers, could produce an astonishing 10
  gigawatts of peak power, and that it could be
  built at relatively low cost by making use of
  part of SLACs 2-mile-long linear accelerator.

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Claudio pointed to developments in three areas of
accelerator technology that enabled his proposal

• 1. High-brightness electron sources  In the
  1980s a group at Los Alamos National Laboratory
  showed that so-called radiofrequency (rf)
  photocathode guns, which shine ordinary laser
  light onto a copper cathode to generate
  electrons, could produce very high-brightness
  electron beams. An advanced version of this type
  of gun now provides the electrons for LCLS.
• 2. Preserving electron beam brightness during
  acceleration, transport and compression  To
  achieve collisions in the SLAC Linear Collider
  (SLC) project in the late 1980s, bright electron
  and positron beams from the SLAC damping rings
  had to be accelerated to 50 billion electronvolts
  (GeV), compressed and transported to the
  interaction point while preserving their initial
  brightness. To accomplish this, SLAC developed
  much relevant instrumentation (diagnostics,
  controls, feedback systems, etc.). Claudio
  pointed out that the success of SLC gave
  confidence that this could also be done for an
  even brighter electron beam from an rf
  photocathode gun at the LCLS.
• 3. Undulator technology  Undulators are arrays
  of magnets that are used to bend the paths of
  electrons back and forth. This causes the
  electrons to emit X-ray light for use in
  research. The first permanent-magnet undulator, a
  2-meter-long device conceived by Klaus Halbach at
  Lawrence Berkeley National Laboratory, had been
  tested in SLACs SPEAR storage ring in 1979.
  Since then, longer undulators built with the
  higher precision required for the LCLS had been
  developed at SLAC and many other synchrotron
  radiation labs around the world. The LCLS now
  uses up to 108 meters of undulator magnets.

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Date Tue, 03 Mar 1992 123232 -0700 (PDT)From
WINICKSSRL01_at_SSRL.SLAC.STANFORD.EDUSubject
1-40A FELs using the SLAC LinacTo
A_at_SSRL.SLAC.STANFORD.EDU, HODGSON_at_SSRL.SLAC.STANFO
RD.EDU

• Art Together with John Seeman of SLAC and
  Claudio Pellegrini at
• UCLA, we are working on the basic design
  parameters and layouts of
• 1-40A FELs that would use parts or all of the
  SLAC linac equipped with
• a low emittance gun such as is being developed
  at several places. I
• hope to have something to show you about this
  soon, possibly by the
• end of this week. Pellegrini has agreed to come
  to Stanford on March
• 18 for a follow up meeting. I briefed Keith on
  this today and also told
• him about Burt's request that we convene a
  meeting with Paul Berg to
• discuss biological applications of such a source.
  Is it possible to
• arrange for a first meeting at the end of this
  week? I am gone most of
• next week. Herman

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Monthly meetings starting 4 weeks after
Pellegrini presentation at 4th Generation Light
Source Workshop

• A remarkable feature of these meetings was that
  all the participants had major responsibilities
  in their regular day jobs. I merely sent out an
  email announcing the topics to be discussed at
  the next meeting and they came, often from a
  great distance, out of interest and eagerness to
  contribute their special skills and experience to
  what we all perceived to be an exciting venture.
  Not only did they come to the monthly meetings,
  but many also presented the work they had done
  between meetings.
• At SLAC, their participation in the early and mid
  1990s was tacitly approved, and even encouraged,
  by Burt Richter, then director of SLAC, and
  Arthur Bienenstock, then director of the Stanford
  Synchrotron Radiation Lightsource. Later in the
  1990s, SLAC Director Jonathan Dorfan and SSRL
  Director Keith Hodgson continued this support.
  Apparently, the bosses of scientists from other
  labs also encouraged their participation.
• Claudio, who is now at SLAC, was the driving
  figure in these meetings, engaging specialists in
  all the relevant areas and pointing out where
  more detailed study and experimental RD was
  needed. By November 1992, work done at these
  meetings led to an outside review of a
  preliminary proposal for a 4-nanometer FEL at
  SLAC.
• This first proposal called for equipping the last
  part of the SLAC linac with a new rf photocathode
  gun, compressing and accelerating the electron
  beam to about 7 GeV, putting this beam through a
  34-meter-long undulator located in an existing
  shielded enclosure then in use for the SLAC Final
  Focus Test Beam, and deflecting the X-ray beam
  emerging from this undulator into an experiment
  station in a modified existing building in the
  SLAC research yard.

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March 6, 1992 To Roberto Coisson, Heinz-Dieter
Nuhn, Claudio Pellegrini, John Seeman and Roman
Tatchyn From H. Winick Subject Summary of FEL
plans using SLAC Linac

• I spoke with Claudio just before he left for a
  week in Italy. Claudio is in agreement
• with our plan to calculate a series of possible
  FEL examples as Heinz-Dieter, Roberto and
• I discussed yesterday. This includes refining the
  examples Claudio gave in his draft report
• for 1A and 40A FELs with normalized emittance
  guns of 2.5 mm-mrad and a range of
• other examples such as the following
• 1. Use of the SLC damping rings with normalized
  emittance of 30 mm-mrad when they operate at 1.2
  GeV and about 4 mm-mrad at 0.6 GeV. I assume that
  these are uncoupled emittances so that they could
  be reduced by a factor of 2 with full coupling as
  Roberto has suggested.
• 2. Use of presently available photocathode guns
  with 4 mm-mrad normalized emittance.
• 3. Use of future photocathode guns with 1.5
  mm-mrad.

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Participants in first LCLS monthly meeting March
18, 1992

• Ali Amiry, Karl Bane, Roberto Coisson, Jeff
  Corbett, Albert Hofmann, Phil Morton,
  Heinz-Dieter Nuhn, Claudio Pellegrini, Tor
  Raubenheimer, John Seeman, Roman Tatchyn, Herman
  Winick

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Date Wed, 18 Mar 1992 163757 -0700 (PDT)From
WINICKSSRL01_at_SSRL.SLAC.STANFORD.EDUSubject
Meeting on Scientific Applications of Short
Wavelength FELsTo A_at_SSRL.SLAC.STANFORD.EDUCc
HODGSON_at_SSRL.SLAC.STANFORD.EDU,
WINICK_at_SSRL.SLAC.STANFORD.EDU

• Art
• We had a very good meeting today on linac-based
  short wavelength
• FELs. I am very encouraged and excited about this
  project.
• Thirteen people from SLAC, UCLA, and SSRL were at
  the meeting. We
• reviewed work that has been done and outlined the
  tasks that remain
• along with the people who will carry out this
  work. We agreed to meet
• again on the afternoon of April 13 at SSRL. We
  are planning a paper at
• an international FEL meeting in Osaka in August
  and will be working
• toward a proposal.

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March 25, 1992 To Distribution From H.
Winick Subject Notes on Linac-based FEL Meeting
of 3/18/92

• This was a meeting to discuss the use of the SLAC
  linac equipped with a low emittance photocathode
• gun to drive short wavelength FELs as described
  in the note by Pellegrini. It was agreed that we
• would adapt three standard wavelengths at which
  calculations will be made. These are 140 A, 40 A
• and 1 A. It was agreed that the tasks listed
  below will be pursued by those indicated. The
  lead person
• is indicated in CAPITAL LETTERS. That person
  will coordinate activities on that task and give
  a
• progress report at the next meeting. The next
  meeting is on Friday, April 10 at 1 PM in the
• large third floor conference room at SSRL.

TASKS 1. FEL design, performance and
optimization Coisson, Corbett, Morton, Nuhn,
PELLEGRINI, Tatchyn 2. Gun and acceleration to
70 MeV Morton, Pellegrini, Raubenheimer, SEEMAN
3. Beam transport and acceleration from 70 MeV
including compression Bane, RAUBENHEIMER, Seeman
4. Wiggler Coisson, Halbach, TATCHYN 5.
Layout SEEMAN, Winick 6. Scientific
applications Tatchyn, WINICK Distribution
Meeting attendees, M. Cornacchia, K. Halbach
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Date Thu, 16 Apr 1992 183803 -0700 (PDT)From
WINICKSSRL01_at_SSRL.SLAC.STANFORD.EDUSubject
Notes on 4/10/92 FEL meeting send
comments/corrections to H. Winick

• Attendees Karl Bane, Max Cornacchia, Klaus
  Halbach, Kwang-je Kim, Phil Morton, Heinz-Dieter
  Nuhn, Claudio
• Pellegrini, Don Prosnitz, Tor Raubenheimer, David
  Robin, Ted Scharlemann, John Seeman, Roman
  Tatchyn, Herman
• Winick, Dandan Wu
• This was a follow up meeting to the meeting of
  March 18. The next meeting will be at noon on
  Tuesday, May 19.
• Lunch will be provided.
• The following was discussed at this meeting
• 1. Several examples of 40 A and 1 A FELs were
  presented by Kim, Pellegrini, and Tatchyn. Each
  of these was
• requested to send a write-up on their work,
  particularly on the 40 A case, to Winick for
  distribution to others.
• 2. Seeman showed layouts and photographs of the
  possible locations for the FEL and experimental
  area.
• 3. Morton gave information about measurements
  taken at Los Alamos with their photocathode gun.
• 4. Raubenheimer reviewed the work done by him
  Bane on pulse compression, wake fields
  emittance degradation.
• 5. It was agreed that we would prepare a paper on
  this project for the International FEL meeting in
  Japan, Aug. 24-28.

• SUMMARY OF TASKS
• Write-up examples of cases for a 40 A FEL at
  different electron energies and different long
  undulators. HALBACH, KIM, TATCHYN.
• Based on above, decide on one example of a 40 A
  FEL to be detailed and costed based on trade-offs
  among output power, beam energy, and undulator
  length. PELLEGRINI, WINICK
• Carry out one detailed example of beam
  compression and transport. BANE, SEEMAN,
  RAUBENHEIMER
• Do full simulation with additional focussing and
  including error analysis using FRED. PELLEGRINI,
  SCHARLEMANN
• Do a design for the photocathode gun. HALBACH,
  KIM, PELLEGRINI
• Do a layout of a facility at sector 10. Can we
  bend 3-40A light by large angles using
  multilayers? PIANETTA, SEEMAN, TATCHYN, WINICK
• Describe possibilities for using several bunches
  within one linac macropulse. SEEMAN. Implications
  for laser gun. PELLEGRINI
• Distribution Attendees, Jeff Corbett, Albert
  Hofmann, Piero Pianetta

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First LCLS Project Schedule April 1992
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ABSTRACT FOR THE INTERNATIONAL FEL CONFERENCE IN
JAPAN IN AUGUST, 1992

• A 4 nm High Power FEL on the SLAC Linac
• C. Pellegrini, J. Rosenzweig, UCLA
• A. Bienenstock, K. Hodgson, H.-D. Nuhn, P.
  Pianetta, R. Tatchyn, H. Winick, SSRL
• K. Bane, P. Morton, T. Raubenheimer, J. Seeman,
  SLAC
• K. Halbach, K.-J. Kim, LBL
• J. Kirz, SUNY Stony Brook
• We discuss the characteristics and performance of
  a 4 nm SASE FEL, using a photoinjector to
• produce the electron beam, and the SLAC linac to
  accelerate it to an energy up to 10 GeV. One
• longitudinal bunch compression at an intermediate
  energy will increase ten fold the peak
• current to a value of 2 kA, while reducing the
  bunch length to the sub-picosecond range. The
• saturated output power of the FEL is in the
  multi-gigawatt range, producing about 1014
• coherent photons with a bandwidth of about 0.5
  (1 standard deviation) in a radiation pulse of
• several millijoules. At a 120 Hz repetition rate
  the average power is about 1 W. The system
• performance is optimized for x-ray microscopy in
  the water window around 4 nm, and will
• permit imaging a biological sample in a single
  sub-picosecond pulse. Details of biological
• applications and the planned experimental layout
  will be presented.

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Nov. 1992 First review of design for a
water-window FEL

• Charge to the Committee
• Critically review the plans for short
  wavelength coherent light sources using the SLAC
  linac with particular regard to the following
• Assess the basic feasibility of the project
• Indicate the particular areas in which individual
  work needs to be done to reach the level of a
  comprehensive conceptual design report
• Where more than one option is presented (e.g.
  high or low energy electron beams) give your
  opinion of the relative merits

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LCLS Technical Review Nov. 20-21, 1992
Reviewers Ilan Ben-Zvi (BNL) - Chairman Joseph
Bisognano (CEBAF) Luis Elias (CREOL - Univ. of
Central Florida) John Goldstein (Los
Alamos) Brian Newnam (Los Alamos) Kem Robinson
(STI Optronics) Ross Schlueter (LBL) Andrew
Sessler (LBL) Richard Sheffield (Los Alamos)
24

• Nov, 1992 First review of design for a
  water-window FEL Ilan Ben-Zvi Chair members.
  Bjorn Wiik was observer.
• Recommendations need gun rd, need demonstration
  that SASE works at short wavelengths shorter than
  cm, which was done in an LLNL/LBL collaboration.

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TECHNICAL REVIEW REPORT (excerpts) LINAC COHERENT
LIGHT SOURCE SLAC, November 20-21 1992
The LCLS wavelength of 40Å is a big jump beyond
that of any FEL that has been built and tested.
We believe that the LCLS is feasible, but only a
careful R and D program and a phased approach
will give confidence that it will perform as
expected. Very few comparisons of theory and
experiment exist for a SASE amplifier which is
the basic design of the LCLS project. In view
of the paucity of such comparisons from previous
FEL experiments, and in view of the large
extrapolation in wavelength from those
experiments to 40Å, the wavelength of the LCLS
device, it is strongly recommended that
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TECHNICAL REVIEW REPORT (continued) LINAC
COHERENT LIGHT SOURCE SLAC, November 20-21 1992
Further experiments should be developed at
intermediate wavelengths (at least two widely
spaced wavelengths). In this way theory and
simulation can be benchmarked and
verified. Furthermore, we believe that a credible
path for this project requires a phased approach,
and preliminary thoughts of a possible path are
presented - Experiments with 10 MeV
photoinjector. - Acceleration to 100 MeV
preserving the emittance and energy spread. -
Pulse compression without significant emittance
degradation. - Construction of a short undulator,
measurement of spontaneous emission. -
Realization of the full soft x-ray FEL
facility. In closing, we would like to state
emphatically that If no resources are provided
for the development of the Conceptual
Design Report and the benchmarking experiments,
important scientific opportunities may be missed.
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TECHNICAL REVIEW REPORT (continued) LINAC
COHERENT LIGHT SOURCE SLAC, November 20-21 1992
In summary, some demonstration experiments are
required to ameliorate the concerns of the
performance of the photoinjector. In particular,
the following demonstrations would reduce the
uncertainty considerably 1) lt3 mm-mrad
emittance, 2) 4 ps FWHM pulses from a
photoinjector with less than the required jitter,
and 3) a reliable laser system.
Since the compression process depends on a
delicate balance between wakefields and applied
fields (with strongly off-crest operation),
maintaining a low level of both current and phase
fluctuations are critical elements in
successfully reaching the desired peak current.
The LCLS design team has discovered this problem
in its modeling, and has set specifications of
current fluctuations at less than 1 and phase
fluctuations at less than 0.2 degrees. These will
be difficult numbers to achieve for the laser
that illuminates the photocathode.
In conclusion, the Review Panel feels that there
are no show-stopping issues that prevent the
realization of a 50 meter undulator for the LCLS
Project. The main concerns are ones of proceeding
with deliberate care during the design of the
device.
A concerted attempt should be made to carefully
design and carry out a program of comparison of
theory and simulation predictions with
experiments on the UCLA 10µm experiments.
It is highly recommended that experimental data
be obtained to substantiate mirror survival at
the predicted intensities at sub-ps pulsewidths
and for irradiation areas comparable to the mm
spot sizes anticipated for this application.
28
Workshops to build the scientific case
Paraphrased comment by a prominent biologist We
have no interest in an expensive x-ray laser in
the water window. We get all we need by
examining cells with cryo-electron microscopy.
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An order by SSRL Director Art Bienenstock

• If biologists dont appreciate a water window
  (30-40 Å) FEL, go to 1 Å.
• I know that material scientists will find good
  uses for such a source.

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More workshops on the scientific case
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Collaboration to Produce Improved RF Photocathode
Guns August 1993
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Next Version Photocathode RF gun
Laser Port
Photocathode
Electron Beam Exit
Full Cell
Half Cell
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Linac and Diagnostics
J. Schmerge Gun Test Facility at SLAC/SSRL
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SLAC/BNL/UCLA 3 photocathode rf gun (left)
symmetrized by a vacuum pump-out port installed
directly opposite the RF feed-in port and a
PARMELA simulation of its minimal attainable
emittance (right) using a solenoidal magnetic
compensation scheme. The discontinuous drop
results from energy-tail halo scraping of the
electron beam.
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A 2-4 nm Linac Coherent Light Source (LCLS) Using
the SLAC LinacPresented at PAC 93
H. Winick, K. Bane, R. Boyce, G. Loew, P. Morton,
H.-D. Nuhn. J. Paterson, P. Pianetta, T.
Raubenheimer, J. Seeman, R. Tatchyn, V. Vylet
SLAC C. Pellegrini, J. Rosenzweig, G. Travish
UCLA D. Prosnits, E.T. Scharlemann LLNL K.
Halbach, K.-J. Kim, M. Xie LBNL

• Abstract
• We describe the use of the SLAC lilac to drive a
  unique, powerful, short
• wavelength Linac Coherent Light Source (LCLS).
• Operating as an FEL, lasing would be achieved in
  a single pass of a high peak
• current electron beam through a long undulator by
  self-amplified spontaneous emission (SASE).
• The main components are
• a high brightness rf photocathode electron gun
• pulse compressors
• about 1/5 of the SLAC linac
• and a long undulator with a FODO quadrupole
  focusing system
• Using electrons below 8 GeV, the system would
  operate at wavelengths down to about
• 3 nm, producing 210 GW peak power in sub-ps
  pulses.
• At a 120 Hz rate the average power is 1 W.

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• Presenting the conclusions of the working group
  on X-rays at the ''4th Generation Light Sources
  Workshop, held at Grenoble in 1996, the
  chairman, J. Als-Nielsen, made a ''Wish List for
  4th Generation Sources''.
• He listed lower emittance, shorter pulses,
  higher average brightness, much higher peak
  brightness, circular polarization, tunability
  from 0.15 to 0.05nm, multiple beams, fundable
  construction and operational cost. His final
  conclusion was ''
• The Hard X-ray group is unanimously excited
  about the FEL project as a 4th generation light
  source''.

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SASE demonstration experiments at shorter
wavelengths
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An Important SASE Demonstration Experiment
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LEUTL lases 0.53 microns at APS/Argonne Oct. 2000
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DOE Review Committee (Birgeneau/Shen) recommends
3M for FEL rd in FY 98
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Leone Panel, 1999 Need stronger scientific case
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The first five experiments G.K. Shenoy and J.
Stöhr (edts.), SLAC-R-611, (September 1, 2000)
Atomic Physics Experiments Plasma and Warm
Dense Matter Studies Structural Studies on
Single Particles and Biomolecules
Femtochemistry Studies of Nanoscale Dynamics
in Condensed Matter Physics
DOE takes notice!!
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Claudio in the LCLS Tunnel
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• End of Presentation
• Thank you