Director's Corner

27 July 2005

Barry Barish

I am often asked where the ILC will be sited The mere fact that I am asked such a question tells me that some of you think we know more than we are revealing about where the ILC will eventually be located. But I must tell you the simple truth that no one knows where the ILC will be sited! (Period)

Alternatively, I am asked how the ILC site will be determined. That is a better question, but unfortunately, I must again give you a disappointingly simple answer that no process has yet been defined. However, we can foresee how to approach that question. Although no details have yet been worked out, it is generally expected that GDE and its parent oversight committees will soon begin to work out how and when "bids to host" will be solicited, what kind of guidelines will be set and how the decision will be made. Clearly, this is a very challenging task. One need only look at the process of making the final site choice for ITER.

I will undoubtedly return to the crucial question of where the ILC will be sited, as the plans for soliciting "bids to host" become clearer, or when some country or region comes forward with an offer. In the meanwhile, it is probably useful for me to outline for you how I envision approaching site issues in the GDE process and to mention a few illustrative design questions. It became apparent to me while I was contemplating whether to accept the GDE directorship that to make a realistic design we will need to face up to a set of issues that are site specific, even before we have a site.

A major issue is cost. We learned from earlier cost studies that civil construction and related infrastructure account for a significant part (~ 25 percent) of the total ILC costs. Therefore, we must be as cost conscious as possible about civil costs and very careful in setting requirements for the civil facilities for any site proposal. Even if we expect civil costs to be borne by the host country or region, we must define our requirements for a site very carefully. Defining these requirements will be one of the products of the design work next year. We want to be able to give the best possible guidance for a "bid to host" solicitation, whenever that is made.

Since the ILC involves large underground tunnels and facilities, there are many areas common to other underground facilities, including geological, tunneling, environmental, safety and other issues. There is also a set of issues that are specific to the ILC, such as whether the entire accelerator complex should be housed in a single tunnel (as in the TESLA proposal, reducing costs) or whether it should be in two tunnels (easing access for maintenance and therefore potentially increasing up-time). So the question comes down to whether it is realistic to have one tunnel or whether it is worth the extra cost to have two tunnels. Other issues include the differences in how we would design and build the accelerator, using deep or shallow tunnels; analyzing differences between a "laser straight" linac and one that follows the curvature of the earth (at least in segments), etc.

It should be apparent that civil engineering issues are intimately tied to details of the machine design. For that reason, I decided to create a Civil and Siting effort within the GDE from the very beginning. This group will lead an effort to work these issues. They will interact first with the choices made during the coming months in defining a baseline configuration. Then the civil and siting work will be an important part of our reference design efforts next year. We plan to use "sample site" information from all three regions as input, in order to create a reference design that is as realistic as possible. We will evaluate the key issues over a wide range of possible site types for the ILC, to identify site specific design issues for the accelerator.

I feel very fortunate to have attracted three senior civil engineering experts to our GDE staff, all of whom bring a great deal of high energy physics project experience. The leaders of the GDE Civil and Siting efforts will be Atsushi Enomoto of KEK, Jean-Luc Baldy of CERN and Vic Kuchler of Fermilab. This group has already begun to create a "strawman" matrix that will contain the important site specific factors to be considered in making the reference design.

At Snowmass, essentially the working groups formed last fall at KEK will remain the main organizing principle for the accelerator workshop. In addition, we decided to create a set of global groups to begin some of the overall efforts needed for a reference design. These global groups will meet several times during the first week in the late afternoon. Global Group #4 will be on the topic of Civil and Siting and will be led by our three GDE civil experts: Enomoto, Baldy and Kuchler. If you are interested in some of the civil and siting issues that I mention above, this global group should provide a lively and interesting forum for initial discussions.