AAC08 Day 1

It was a long but interesting first day. The agenda was filled with plenary sessions, and the afternoon student poster session/competition.

The workshop was opened by high-energy physicist Hitoshi Murayama of IPMU-Tokyo and UC Berkeley. His talk was on the physics beyond the LHC. Basically he was giving a brief tutorial of high energy physics (both accelerator based and in particle astrophysics) and what to expect beyond the LHC. The motivation here was to give an idea to particle accelerator community what kind of technology that one can start to expect as soon as the first set of results from the LHC comes in.

The one thing that he kept emphasizing, possibly because of the crowd that he was addressing, was that particle accelerators have been THE enabling technology for particle physics. He emphasized that many non-accelerator physics discoveries had to be confirmed, studied, and improved using accelerators.

Murayama then established why the TeV energy scale is so crucial. This is the scale that corresponds to a length scale of 10^-17 cm, which is the scale of the short-ranged weak force. He actually described why the ILC is needed even if the LHC sees signature of the the Higgs (or many different types of Higgs). The ILC would produce a "cleaner" signal to allow high energy physicists to narrow down the Higgs properties that the LHC would find.

All in all, it was an effective "fan mail" from high energy physics community to the accelerator physicists. :)

The second talk in the morning plenary session was by Tor Raubenheimer on the Future R&D for Very High Energy Colliders. He basically listed the relevant parameters of the accelerator technology that is needed beyond the LHC. This essentially mirrors the ILC technical report, and the recent P5 report from last June. It boils down to these 2 numbers for the ILC:

1 TeV and luminosity of 1 x 10^34 cm^-2 s^-1

The estimated cost in 2020 dollars (assume an inflation of 3.5%) is $20-25 billion. The majority of the cost (60%) is estimated to be in the main linac section. So the acceleration scheme costs the most. Finding something that can substantially lower the cost of the accelerating section would substantially lower the total cost.

Next to talk was Pisin Chen of Kavli Institute/SLAC on Laboratory Astrophysics. He talked about particle astrophysics, dark matter, and high energy-density physics. He also argued that intense laser field in an electron accelerator can, in fact, probe the Hawking-Unruh effect.

Chris Barty of LLNL described the current status of the Livermore's laser technology (he jokingly described LLNL to not mean Lawrence Berkeley National Laboratory, but rather Laser, Laser, and Nothing but Laser). He spent quite a bit of time describing the laser system at the National Ignition Facility. That facility is obscenely impressive. I mean, anyone who is familiar with high-powered laser can't help but be impressed by what they have done there. It's just a jaw-dropper of the technical difficulties that they faced and have overcome. He also showed a video on how they actually used a laser with a spot 4 inch x 4 inch and simply melted a thickness of aluminum in seconds! Holy Cow!

Cameron Geddes of LBNL then proceeded next to describe all the progress made in laser-driven plasma wakefield acceleration scheme. This is the scheme that has made significant progress (and publicity) in achieving huge gradients. It is simply amazing the amount of progress that has been accomplished in this field, and they continue to refine the technology. This is a serious contender for the next acceleration scheme in future generation of particle accelerators.

After the lunch break, Wei Gai from Argonne described the Advanced Accelerating Structure and their interactions with electron beam. Basically it reviewed the effect of electrons passing through dielectric-loaded accelerating structure, photonic band-gap structure, and meta-material/left-handed structures.

Tom Katsouleas (who used to be at USC but is now at Duke University) described another type of plasma wakefield scheme. This time, instead of laser driven which was described by Geddes, it is electron-beam driven. This is where a bunch of electron passing through a plasma can create an accelerating wakefield for a witness beam that follows it. The current demonstration has shown the acceleration of an electron bunch from 42 GeV to 85 GeV in 1 m. That's pretty impressive. He also spent time showing a realistic concept of plasma wakefield accelerator for a linear collider, a facility that is being set up at SLAC.

I spent some time going around the student's poster session, which occupied 3 different rooms. The judges were already going around to different posters. Good luck to all the students!

Zz.