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Science Today: "ILC Tribes" Gather

Last month Fermi National Accelerator Laboratory served as host for a "gathering of the International Linear Collider (ILC) tribes." Three back-to-back meetings covered superconducting (SC) technology R&D, an international review of the ILC Global Design Effort (GDE) and a review of R&D progress in the Americas.

The first meeting was of a collaboration formed during the transition from the DESY-based TESLA linear collider initiative to the ILC. The TESLA Technology Collaboration, now headed by Maury Tigner from Cornell, meets about twice a year to review progress in the development of SC cavities, which are at the heart of SC linacs. This group’s earlier members pioneered methods to improve cavity performance that have made SC technology the preferred choice for linacs today. Applying new processing techniques and better quality control, they increased the sustainable gradients in 9-cell cavities from 5-10 MV/m to 25-35 MV/m over the past decade. These improvements have led to the use of SC technology in machines such as the Spallation Neutron Source at Oak Ridge.

The TTC now aims to improve the reproducibility of the gradients achieved at the high end of the spectrum to make both the European XFEL project and the ILC cost effective. They have been joined by physicists from JLAB, Cornell, Fermilab and KEK who are now investing heavily in infrastructure to be at the forefront of this technology along with DESY. While the initial results from these new programs have been promising, much more research is needed to perfect a production recipe that routinely results in cavities that achieve 35 MV/m as required for the ILC (currently there is a wide spread in gradients with a mean of about 28 MV/m). Perhaps the most important outcome of the recent meeting is that these efforts are now being coordinated more internationally. And there is motivation to do even better as a Cornell/KEK collaboration reported achieving 58 MV/m in a specially shaped single-cell cavity.

The next meeting was an ILC Machine Advisory Committee (MAC) review of the R&D being directed at the linear collider. Funding for this work comes from many different sources and the R&D programs are not managed by the GDE organization, although it works to shape the priorities at the major labs. Not surprising, the MAC was particularly concerned about coordination of the R&D efforts, duplication of work and the efficient use of current facilities. These concerns are in fact being addressed in the current effort to reorganize the ILC to have clearly delineated work packages. This new organization should be finalized in the next few months.

In the U.S., the Department of Energy (DOE) funded ILC R&D is managed through a series of work packages with leaders from the different labs. This group is referred to as the Americans Regional Team (ART) and is now headed by Mike Harrison of Brookhaven National Laboratory. In the last of the meetings at Fermilab, the ART work package leaders met to present progress and discuss plans for the coming years to a DOE review. The biggest efforts cost-wise are the cavity and cryomodule development at Fermilab, and the rf system development at SLAC. SLAC also has a major role in the ILC beam delivery and source development. The DOE ILC and SCRF funding is expected to grow from $68 million in FY07 to $76 million in FY08 and over $100 million in FY09. A major goal is to have an rf unit operational at Fermilab by 2010 that consists of three, 8-cavity cryomodules powered by an ILC-like rf system provided by SLAC.

óChris Adolphsen, SLAC Today, May 24, 2007