Linac Coherent Light Source Update

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Office of Basic Energy Sciences Office of
Science, U.S. Department of Energy
Linac Coherent Light Source Update
Eric A. Rohlfing BESAC Meeting February 26, 2001
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Scientific Case for the LCLS

• LCLS The First Experiments
• Scientific case directly tied to decision on
  proceeding with LCLS construction (Critical
  Decision 0 - Conceptual Design)
• Aimed at defining (in some detail) the first
  classes of experiments that would be mounted on
  the LCLS
• Basis for experimental requirements for the LCLS
  CDR
• Assembled through the LCLS Scientific Advisory
  Committee

• Reviews
• Presented to and discussed by BESAC in October
• Unanimous vote to recommend that BES approve CD0,
  contingent upon positive external peer review
• External peer review completed in November - 13
  reviews (out of 20 contacted)

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Reviewers Comments

• General
• Very similar to BESAC comments and generally
  positive
• Several reviewers noted significant improvement
  over earlier efforts
• Tendency for reviewers to favor science outside
  their area of expertise

• Specific Areas
• (1) Atomic Physics
• Agreed that these studies are basis for
  understanding intense x-ray-matter interactions
• Criticized for not being innovative concern
  about lack of impact on field
• Concern over interpretation of nonlinear
  processes with spiked temporal structure (lack of
  longitudinal coherence) in LCLS pulses

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Reviewers Comments

• Specific Areas
• (2) Plasma and Warm Dense Matter
• Clear niche role for LCLS, particularly as a
  pump source to create WDM
• Concern over broader impact and relevancy to
  BES, but noted clear relevancy to DOE Defense
  Programs

(3) Structural Studies on Single Particles and
Biomolecules Most positive set of comments
clearly at forefront of field with huge potential
impact But, some skepticism, not concerning
damage model, but whether there would be
sufficient signal-to-background to extract
molecular structure information
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Reviewers Comments

• Specific Areas
• (4) Femtochemistry
• Weakest set of reviews from those most directly
  associated with ultrafast dynamics (stronger from
  those outside)
• Concerns with synchronization between laser pump
  and LCLS probe
• Clear need for shorter pulses in order to have
  real impact in dynamics, particularly in the gas
  phase

(5) Studies of Nanoscale Dynamics in Condensed
Matter Physics Few review comments (little thin
on reviewers) Not clear that LCLS parameters are
ideally suited to experiments damage
calculations for XPCS look marginal
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Reviewers Comments

• Specific Areas
• (6) X-ray Laser Physics
• Few comments (again a bit thin on reviewers)
• Strongly endorsed attempts to shorten LCLS pulse
  based on scientific needs, particularly for
  Femotchemistry

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Path Forward

• BES has delayed approval of CD0
• Strong support for the LCLS project, but.
• Scientific case and level of community support
  not yet sufficient

• BES Workshop on Scientific Applications of
  Ultrafast, Intense, Coherent X-Rays
• Organizers Eric Rohlfing and Pedro Montano, BES
• Focus scientific applications of source with
  LCLS specifications with emphasis on ultrafast
  dynamics, nonlinear optics, x-ray imaging
• Participants 20-25 scientists LCLS veterans
  with newcomers
• Logistics May 4-5, 2001 Wardman Park Marriott,
  Washington, DC
• Output report that complements and broadens
  LCLS scientific case

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BES Vision for the LCLS

• LCLS is partly an accelerator/FEL RD project,
  but it must also be..

• A stand-alone scientific user facility

• The LCLS is not a step along a predetermined
  path toward a larger XFEL facility