After an unbelievable 8 years, I finally made it back to CERN. For a particle physicist, this is an incredibly long absence from the lab that now has evolved into the center of the particle physics universe. However, I have many good reasons for this long absence, since I’ve been working on non-CERN projects ever since leaving CERN after my diploma thesis in September 2001. And, where integrated time is concerned I’m still doing ok: Back then I spent a whole year here…
The reason for my trip was a look ahead to the future: CERN has recently joined the CALICE collaboration, and I’m hoping for a fruitful collaboration to solve at least some of the challenges for detectors at a possible future multi-TeV lepton collider, the CLIC machine that Lucie already briefly mentioned. Here, also the hadron calorimeter brings up all sorts of new and interesting questions. To contain showers of much higher energy, a deeper detector, potentially with a much denser absorber such as Tungsten, is needed. And for Tungsten, the evolution of hadronic showers is still very poorly known. To address this issue, a new program within CALICE has been launched, and I’m happy to be a part of this newly developing initiative.
Here, I also can’t resist to slip in a comment on Lucie’s question if now is not the time to focus on getting the LHC running, instead of planning the next big machine. And I have to say that I strongly disagree: It is absolutely essential that we now focus also on what might lie ahead, how the next generation of accelerators will look like, otherwise particle physics might not have a future. The R&D and construction cycles for these big experiments are now measured in decades, so we have to have a future plan for projects which come after the LHC. And since it is not clear how the new physics will look like, we need to be prepared: For lower energies, we have the well-defined ILC as a precision machine to give us a thorough understanding, but if new stuff only shows up above many hundreds of GeV, then we need a different technology, which the CLIC concept can provide. Of course, this is not “shovel ready” yet, a lot of R&D, both on the machine and on the detectors, is still required.
Just to set the time scales here (and the are even longer nowadays): The discussions and studies of LHC began in the early 1980s (at that point, I was in Kindergarten!). First beams in LEP were in 1989. Then, in 1994, LHC was approved by the CERN council. And hopefully we get first collisions still in 2009. Now, if you extrapolate this good quarter of a century from the first studies and concepts to collisions it is immediately apparent: if particle physicists don’t now also work on the next big project, none of us, from the grad student level upwards, will see any new machine in their professional life. So while getting the LHC under way should absolutely be the top priority in particle physics right now, we have to already be well advanced with the planning for what might come afterwards right now (and luckily we are).
Of course, as Lucie also mentioned: It is an ambitious, risky program: We are betting on a spectacular physics output from the LHC experiments. Here, I am quite optimistic, but I guess that is obvious, otherwise I should have picked another field to work in. Without good, convincing results it will obviously be hard to justify a new, large scale project. On the other hand, I don’t think there is a risk that “LHC will find everything”. If we are lucky, it will answer some of our questions, and give us new ones to pursue, and maybe even send us into a totally unexpected, new direction.
