third-generation synchrotron sources that are just beginning to operate. This exploration, in conjunction with further research and development of x-ray FEL technology, will provide the basis for an informed decision regarding possible future construction of an x-ray FEL facility.

  1. Even if cost were not a factor, construction of an x-ray free electron laser would require significant research and development, particularly at the shorter wavelengths.

  2. The costs and risks of building a free electron laser facility would be much higher in the x-ray region than in any other region, and the uncertainties in both the cost and the technology are also much higher.

Recommendations
  1. Scientific opportunities and the use of coherence in the x-ray spectral region should be explored initially by the use of existing and planned synchrotron sources.

  2. The research and development necessary for the possible construction of an x-ray free electron laser should be supported. The goals of this research and development should be improving the technology and lowering the cost.

  3. Research and development on other advanced coherent x-ray sources should continue to be supported. One of the goals of this research and development should be the production of devices of appropriate size and cost to be useful for scientific research on a departmental or individual-investigator scale.

  4. Construction of an x-ray free electron laser user facility should not be undertaken at the present time.

GENERAL ISSUES

There were several issues that the committee believed were important but that were general and did not fit into the sections on individual wavelength regions.

A variety of communities potentially benefit from the type of research that will be necessary to produce scientifically useful FELs, and because of the huge disparity in resources among these communities, it is unrealistic to expect any single one of them to assume the financial obligations for all, or even any significant fraction, of the total cost. Because each of these communities tends to focus tightly on its own principal interests, there is little impetus for cooperation directed toward the development of FELs. Unless this happens in the future, the technological promise could be unfulfilled. A thorough analysis of this aspect of the problem would require an in-depth study of all of these communities: accelerator physics, high-energy physics, the Defense Department, industry, and the National Laboratories, including the synchrotron laboratories. Such an analysis is clearly



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