S. Brennan

In response to the proposal by Helmut Wiedemann and others that the magnet structure and vacuum chamber of SPEAR be upgraded (see the article by Bob Hettel in this Newsletter), SSRL, the SSRL Users' Organization, and the SSRL faculty sponsored a one and one-half day workshop on May 29-30, 1997.

The goal was to assess and document the impact of this new lattice, known as SPEAR3, on current and future science and technology research programs of the users of SSRL. The hard and soft X-ray beams produced at SSRL are used in a number of different scientific and technological disciplines. The workshop was organized by defining a set of areas of science and technology covering the basic activities at SSRL and inviting key people from outside Stanford to work with the SSRL faculty and staff in a set of topical groups on estimating the impact of SPEAR3 on their respective fields and developing a vision of the future opportunities.

The roughly 70 scientists who attended the workshop were split into 8 working groups, namely:

Biological Macromolecular Crystallography
Biological Small-Angle X-ray Scattering and Diffraction
Biological X-ray Absorption Spectroscopy
Molecular Environmental Science
Materials X-ray Absorption Spectroscopy
Imaging/Tomography/Topography
Condensed Matter, Materials Science and Technology
VUV and Soft X-ray Science

Prior to the convening of the working groups, details of the proposed upgrade were presented by Sean Brennan, Bob Hettel and Tom Rabedeau. Gordon Brown spoke about the impact of SPEAR3 on his field, molecular environmental science.

Each working group created a document detailing the impact of SPEAR3 on their field. In addition, some groups were able to identify new beam lines which would be particularly attractive with the new lattice. These include an undulator beam line for the 1-4 keV energy regime, and a vertically polarized wiggler for the 10 keV region. The reports were combined, along with an executive summary and a technical description, into report "SPEAR3 Workshop: Making the Scientific Case", SLAC Tech. Pub. SLAC-R-513.

The conclusions of the workshop were:

• The important new opportunities for science and technology afforded by SPEAR3 provide compelling reasons to proceed in the most rapid way possible with the SPEAR3 upgrade.
• In parallel with the machine upgrade, the program to improve the beam line optics is crucial and these improvements should be timed to take full advantage of the machine upgrades as they happen.
• The use of undulators on SPEAR3 will provide unparalleled capabilities in the soft (1-4 keV) spectral region.
• SPEAR3 will provide extremely valuable long straight sections (several 4-meter straights, and 2 even longer ones). Plans should be evolved to develop these capabilities.

The conclusions drew clear praise from the SSRL Users Organization Executive Committee, which included a letter expressing their strong and enthusiastic support for the proposed upgrade. For more detailed information, the executive summary is available on the WWW, at:
http://ssrl.slac.stanford.edu/pubs/reports/spear3_report.html