Kamran Vaziri and Don Cossairt
At the time of this writing Fermi National Accelerator Lab's (Fermilab's) 2007 shutdown, which started August 6, is in full throttle. The coordinated effort started weeks before the actual shutdown started. Original ALARA planning of several major jobs predicted the total shutdown dose of several tens of person-rems. With the help of some preliminary surveys and careful planning of the schedules, the total accrued dose as of today, about three weeks before the end of shutdown, is 5.9 person-rems. In addition to an enormous amount of maintenance, the main projects are replacement of the pi-shaped power poles and installation of collimators and new corrector magnets in the Main Injector and Booster accelerators.
In order to control beam losses in the Main Injector, new collimators are being installed that will shield the rest of the accelerator from the lost beam. The new steel and marble collimators will take about 10 weeks to install and will help keep residual radiation levels in the tunnel low. The new correction magnets going into the Booster will make it possible to correct the Booster orbit through the entire cycle. Half the magnets will be installed now, and the other half will be installed during another shutdown.
Fermilab's Collider Program Run II is expected to end by 2009-2010. This may end the Tevatron collider experimental era. Fermilab has clearly committed to the International Linear Collider (ILC) as a high-priority, long-term goal. However, the lab would need a viable program during the gap between the closure of the Tevatron and the construction of ILC. The idea of the gap is reinforced by an observation from Ray Orbach, Under Secretary for Science of the US Department of Energy, that processes to get funding, international agreements, and a site for the ILC could stretch the completion date to well beyond our technically driven time scale. Based on the recommendation of a steering committee, composed of Fermilab staff and outsiders, an interim accelerator project (Project X) aligned with the longer-term ILC was chosen.
Project X is an intense, 8-GeV linear proton machine, using ILC-like superconducting radiofrequency (RF) technology. This linac will produce a 200-kW, 8-GeV proton beam that could be injected into the Main Injector, accelerated to 120 GeV, and fast-extracted to make an intense neutrino beam. The 8-GeV beam and the 120-GeV beams could also be slow-extracted to support a broad-based, precision physics program. The goal is an eventual 2.3-MW proton beam. The general scientific goals are a future generation of neutrino physics and a varied program of precision measurements. However, the radiological challenges of these high-power, high-intensity machines are more than fascinating!