Fermilab Steering Group Report


Appendix B: Fermilab and the ILC


Fermilab's International Linear Collider and superconducting radio-frequency program is coordinated with the ILC Global Design effort and respects U.S. regional priorities. Fermilab's ILC effort focuses on the main linac, based on SCRF technology, and the design of conventional facilities, the largest cost drivers of the ILC. Key elements of Fermilab's main linac program include cavity and cryomodule fabrication and testing, related infrastructure development, advancing U.S. industrial capabilities, and developing designs and technologies to improve ILC performance and reduce cost. A collaboration of U.S. institutions under the leadership of the American Regional Team of the GDE is carrying out the U.S. ILC R&D program, which will build and install SCRF infrastructure at U.S. laboratories including Fermilab. DOE has supported Fermilab to develop its SCRF infrastructure. The goal is to advance the ILC and to establish the U.S. and Fermilab as a credible, qualified host of the ILC. The technical goals are:

  • Develop cavity-processing parameters for a reproducible cavity gradient of 35 MV/m; improve the yield of nine-cell cavities at 35 MV/m in vertical tests. Carry out parallel and coupled R&D on cavity material, fabrication and processing to identify paths to success.
  • Assemble and test several cryomodules with average gradient >31.5 MV/m.
  • Build and test one or more ILC RF units at ILC beam parameters, high gradient and full pulse rep rate. Prepare the plans for and participate in the ILC main linac system test consisting of several RF units.
  • Prepare infrastructure and test facilities to support continued development of cryomodules and to qualify industrially built main linac components and industrially built cryomodules.

The U.S. collaboration has fabricated and treated SCRF cavities for various projects at national laboratories. But the 35 MV/m technique of electropolishing is just starting. The U.S. ILC effort is expanding cavity-fabrication capability in industry and installing cavity-processing facilities to fulfill the needs of ILC R&D. The goal for ILC cavities is 95 percent yield at 35 MV/m. The U.S. goal is to fabricate, process and vertically test about 100 cavities per year, supporting the development of U.S. industrial capability. Thomas Jefferson National Accelerator Facility and Cornell University currently provide modest cavity-processing and testing capacity. New process and test infrastructure under construction at Argonne National Laboratory and Fermilab should allow the U.S. to meet its goal by 2009, allowing the ILC to settle on a process and yield in about two years.

To complete the range of capabilities necessary for establishing core ILC technology in the U.S., Fermilab is installing an infrastructure to test dressed cavities with high-power RF, a cryomodule fabrication facility, and an RF unit test facility to examine cryomodules with an ILC-like beam.

Fermilab leads the effort to design a cryomodule for the ILC. Current efforts include moving the quadrupole to the center of the cryomodule to reduce vibration; developing cryogenic pipe sizes to support higher-gradient cavities; and designing longer cryogenic strings, symmetric cavity end-groups and a new tuner. Fermilab plans to build three cryomodules by the end of FY2010, assemble them into a single RF unit and test them. While this is an important milestone, U.S. preparation to build the ILC requires building tens of cryomodules in the U.S. and developing the industrial capability to produce hundreds.

In the engineering design phase of the ILC, Fermilab has committed to provide key engineers and scientists to develop the design of the ILC. Fermilab also plans to work with U.S. industry to improve cavity and cryomodule design. Accelerator physics design and simulation of the machine will focus on emittance preservation. While working with the worldwide ILC collaboration on the ILC machine design and global site development, Fermilab has special responsibilities to develop a Fermilab site-specific design for ILC.

Physics and detectors

Fermilab's ILC detector R&D program supports the priorities established by Worldwide Study of the Physics and Detectors for Future Linear e+e- Colliders (http://physics.uoregon.edu/~lc/wwstudy/). Focusing on the most demanding aspects for the ILC detectors in collaboration with other laboratories and universities, the program's three areas of detector design are well matched to Fermilab's capabilities. This research is intended to have a broad approach, not limited to a single ILC detector concept.

The main focus is on silicon detectors, deployed either as pixel detectors or tracking detectors. The growing demands on detectors for ILC experiments require novel solutions of semiconductor detectors characterized by improvements in granularity, readout speed, radiation hardness, power consumption and sensor thickness. A current trend in the field of highly segmented ionizing radiation detectors is the development of monolithic active pixel sensors, which combine a pixel detector and readout electronics. Fermilab developers are vigorously pursuing vertical integrated systems with through-silicon via technology in a silicon-on-insulator process. This technology, whose development is driven by industry, holds enormous promise for providing low-mass, low-power particle physics detectors. An integrated approach studies the sensor technology and the mechanical design of vertex detectors as well as tracking detectors. The primary goal is to establish the proof of principle of each technology on a timescale compatible with the start of construction of the accelerator.

A second emphasis is on the characterization of pixelated photon detectors, a new development for photon detection. These PPDs consist of a pixelated silicon substrate, where each pixel operates as an avalanche photodiode in Geiger mode. These devices hold the promise of replacing the photo-multiplier tubes. The devices are fast, operate at room temperature at modest bias voltages, and are insensitive to magnetic fields. Fermilab is working in close collaboration with universities on the characterization of these devices and on their applicability as photon detectors for use in dual-readout calorimeters and scintillator-based muon detection systems.

A third focal point is the development of a test-beam infrastructure. The ILC detectors are precision instruments using technologies never before employed in large-scale systems. Test beams will constitute a critical step in establishing the ILC detector technologies. In 2006, Fermilab upgraded its test-beam facility largely to satisfy the needs of the ILC. As a candidate host laboratory for the ILC and with limited availability of test beams at other laboratories over the course of the next few years, Fermilab intends to enhance test-beam facilities to accommodate the needs of the whole user community.

All detector R&D builds on Fermilab's infrastructure and expertise. As a candidate host laboratory, Fermilab intends to increase the laboratory's effort in ILC-related activities including collaborative work on detector R&D and test-beam facilities and strengthening its role in supporting users. The laboratory will foster a lively and diversified program of R&D projects, for their significance for crucial and cutting- edge technology developments related not just to the ILC but also to the principal themes of world-wide research in particle and astroparticle physics. The laboratory will foster synergies among projects to optimize the scientific output for an intense, cost-effective, goal-oriented research program in collaboration with universities and other laboratories. Fermilab will continue to make the compelling case for ILC physics and to communicate with many audiences to strengthen the laboratory's leadership role in the ILC enterprise.