There are two highly active projects to design a linear collider that would collide electrons and positrons at energies higher than those achieved at LEP. Recently there were workshops discussing the state of the projects.
The ILC is the farthest along of the two and uses more conventional technology. It is a design for a 250+250GeV collider, upgradeable to 500+500Gev. There’s a very jazzy new web-site aimed at selling the idea to the US public. This week Fermilab is hosting a workshop on the ILC, talks available here. Michael Peskin gave an introductory talk with an unfortunate title (“The Physics Landscape”, I really think serious physicists should not be reminding people of this, especially when they’re making a pitch to the public for money). He argues that the LHC will see a spectrum of new particles (in order to solve the hierarchy and dark matter problems), and motivates the ILC as the machine to study these. This of course depends on their existence, at a mass low enough to allow production at the ILC, but high enough to evade bounds from LEP and the LHC (for some new results from the latter, see here). It now appears certain that no decision about building the ILC will be made until results are in from the LHC (2010?) that will resolve whether there are new particles in the mass range that the ILC is capable of studying.
DOE’s Ray Orbach gave a talk about the ILC project, emphasizing:
It is critical that planning for the ILC takes into account the realities of the funding situation, the need to formalize the ILC arrangements between governments, the changing scientific landscape, the scientific capabilities at other facilities, and the health of our national scientific structure.
Orbach seems concerned that the ILC project does not have a realistic schedule (“I judge that these arrangements will require more time than the currently proposed schedule of the GDE”) , and does not have commitments from other countries. I’m guessing that he sees financing it out of the current and expected DOE budget is not doable without large contributions from other countries, and a relatively long time-frame. He emphasized that there is now a well-defined process for projects like this: they have to survive a series of “critical decisions”. The ILC is not yet ready for the first critical decision “CD-0, Mission Need” and won’t be until after the LHC results are in. He also mentions “other planned international projects”, and the importance of not duplicating their activities (I take this to be a reference to CLIC). Finally, he is critical of the plan of the ILC project to move to an “Engineering Design Report” that would give detailed engineering plans for the machine, since he sees it as still in an R and D phase.
Over at CERN, the Resonaances blog reports on a workshop devoted to CLIC, a more ambitious and less technologically developed plan for a 1500 + 1500 Gev collider (upgradeable to 2500 + 2500 Gev). If CLIC really turns out to be feasible, and buildable on a time-scale close to that of the ILC, it will not be possible to justify building the ILC, since it would operate at much lower energy.
This week internet access is more iffy, since I’m in Lisbon, for a conference late in the week on “Is Science Near Its Limits?”, sponsored by the Gulbenkian Foundation. After it is over, I’ll write about it here, and I think I can post a copy of the talk I’ll be giving.
Update: Science magazine has a short piece about the Orbach talk, see here:
Orbach said physicists must follow the department’s protocol that requires a large project to pass five critical decision milestones. The ILC has not passed the first, which allows researchers to proceed from basic R&D to design, Orbach said. Previously, DOE officials had been “completely open” to a less formal approach, says Caltech’s Barry Barish, who leads the design team. What counts as “engineering design” remains to be determined, he says.
Another piece of this story recently pointed out to me is that the new CERN director is from DESY and associated to the ILC project there. This might cause people at CERN to wonder how hard he’ll push for its CLIC projector, which is in some ways an ILC competitor.