Fermilab Steering Group Report

Chapter 5
Facilities for the
Intensity Frontier

Project X

Project X is based on an 8 GeV superconducting H- linac. The downstream 7 GeV would use ILC cryomodules and radio frequency distribution systems, with perhaps some modifications in the transverse focusing arrangement and RF phase adjustment. Project X's front end draws heavily on technology developed by Argonne National Laboratory for a facility for rare isotope beams, the Advanced Exotic Beam Laboratory. Using the Recycler as a stripper and accumulator ring is the key element that allows the linac to run with the same beam parameters as the ILC. The linac operates at 5 Hz with a total of 5.6×1013 H- ions delivered per pulse. They are injected into the Recycler using a standard H- stripping procedure. The total pulse length (1 ms) implies 100-turn injection. The injection process "paints" the beam both transversely and longitudinally to reduce space charge forces.

Following the 1 ms injection, the orbit moves off the stripping foil and circulates for 200 msec, awaiting the next injection. Following three such injections a total of 1.7×1014 protons are transferred in a single turn to the Main Injector. These protons are then accelerated to 120 GeV and fast extracted to a neutrino target. The Main Injector cycle takes 1.4 seconds, producing approximately 2.3 MW of beam power at 120 GeV. At lower proton energies, Main Injector cycle times can be shorter, allowing a beam power above 2 MW in the range of proton energy between 50 GeV and 120 GeV. In parallel, because the loading of the Recycler only requires 0.6 seconds, up to four linac cycles are available for accumulation and distribution of 8 GeV protons from the Recycler. Total available 8 GeV beam power lies in the range of 100-200 kW, depending on the proton energy in the Main Injector. This is an order of magnitude higher than the proton power currently available. different configurations of the Recycler could distribute this beam in any combination of fast or slow extractions required by the physics program. Project X is also compatible with reconfigurations of the Debuncher ring and the Tevatron to support slow spill programs at 8 or 120 GeV respectively, and with the Tevatron High Energy Neutrino Facility. The Tevatron-based programs would come with a modest cost in protons delivered to the neutrino program at 120 GeV, because of the use of a Main Injector cycle to transfer beam to the Tevatron.


Taking full advantage of the increased beam power available from Project X would require changes to the Recycler, the Main Injector and the neutrino target. The Recycler would need a new H- injection system and probably measures to mitigate electron cloud effects, as well as a new (fast or slow) extraction system, and new RF systems. The Main Injector would need a new RF system and measures to mitigate electron cloud effects. Project X would require design and construction of a new neutrino target station to support 2.3 MW operations. Building a spur off the current NuMI beamline would permit directing a beam toward the DUSEL site.

The engineering design for Project X will produce a detailed cost estimate and construction plan. However, we expect that the accelerator portion of Project X would be comparable in size and scope to the Main Injector. Construction would take four to five years with a few hundred FTEs per year. It would be most effectively achieved as an interlaboratory collaboration centered at Fermilab.