More on Heavy Ion Physics from Symmetry/Beaking

The making and tending of heavy ion beams for the LHC

November 15, 2011
Amy Dusto

“This week the Large Hadron Collider began heavy ion physics, the process of colliding lead ions to learn about conditions in the primordial universe.

The accelerator is expected to perform five to 10 times better than it did in its first run of these collisions last November. Although the heavy ion program will last only from now until CERN’s annual winter shutdown just after the first week of December, operators started preparations months in advance. Here symmetry breaking examines what it really takes to put lead beams in the LHC.

The source

Making heavy ions is more complicated than preparing the protons used in regular LHC collisions, which come from hydrogen gas. Since hydrogen atoms have only one proton and one electron each, applying a voltage to them is sufficient to rip off their electrons, leaving a load of beam-ready, positively charged protons. But the source for heavy ions, enriched lead, starts with 82 electrons. Physicists do not have miracle flypaper to grab that many subatomic particles at once, so the process takes a few steps.

Meet Detlef Kuchler, a heavy-ion expert who tends the lead source, the first part of the heavy-ion acceleration process, by hand. He helped develop the method of extracting lead ions decades ago and can explain from memory its hundreds of associated, unlabeled diagrams. Although several people work on the source, a flowchart of what to do when things go wrong at this stage dead-ends everywhere with, ‘Call the expert.’ It may as well say, ‘Call Detlef.’ He spends a lot of nights and weekends at CERN during heavy ion season.”

Heavy-ion expert Detlef Kuchler holds a container of lead. Image: CERN

Kuchler prepares the oven. Image: Amy Dusto

Operators test beams of lead ions in this linear accelerator. Image: CERN

Operators declared “stable beams” today, which means the LHC is ready for heavy ion physics. Image: John Jowett

See the full article here.