From Symmetry Magazine via SymmetryBreaking: “Accelerator soup: Scientists to mix elements in LHC to study recipe for heavy-ion collisions”
Instead of colliding two beams of protons or two beams of much heavier lead ions, as the LHC usually does, operators will try to collide one of each in the coming weeks. On October 31, they will test the process for 16 hours, and two weeks later they’ll get another 24. That’s all the time they decided they could take from the precious month of data-collecting they will give the experiments during the upcoming lead-lead run. If it works, a proton-lead ion research program could be in place for November 2012.
The scientists undertaking the task of colliding protons and lead want to collect benchmark information about single beams of lead ions to get a better picture of what’s going on in lead-lead collisions. For that, the tiny proton acts as a probe of the more massive lead ion.
Theorist Urs Wiedemann explained that it’s a bit like making soup. A meticulous chef wants to know exactly what happens at each step of a recipe. This includes both the initial state of the individual ingredients – onions sautéed or raw? – as well as the final outcome inside the pot. Otherwise the chef can’t make informed changes. Similarly a physicist needs to know the individual properties of both of the elements he or she wants to collide, as well as what their smashing produces, in order to get the full picture for analysis.
CERN physicist Detlef Kuchler holds a purified sample of lead used to create heavy ions for the LHC. Photo by M. Brice / CERN
Snapshot of two lead nuclei just after impact. Image by Henning Weber / CERN
The CERN accelerator complex. Image: CERN
See the full article here.