Friday, March 25, 2016

The Large Hadron Collider - Shifting to Glide

When 2 experiments give you the same
anomalous data...
The Large Hadron Collider in Europe follows a strictly defined schedule. They run proton/proton collisions from spring until winter, finish the year with several weeks of heavy ion collisions using lead nuclei and then spend the next three to four months in their YETS - year end technical stop. During this period they do maintenance and inspections, particularly of the cryogenics system and the four primary experiments, ALICE, ATLAS, CMS and LHCb. Now it's the end of March. That means college basketball championships, the beginning of the baseball season, and restarting the LHC.

Last year was the beginning of what CERN called LHC Run Number Two. The first several years the collider ran at much lower power, then it was shut down and upgraded to its rated energy of 14TeV - two beams at 7TeV each colliding head on at relativistic velocities. This year will be a full year running the collider at full power. Scientists expect to take at least six times as much data this year as they did last year.

There are a number of specific targets of this research. First there is the Higgs Boson - researchers observed the Higgs last year, but they observed it at a surprisingly low mass - about 125GeV. For the particle that carries the field that gives mass to everything that HAS mass, that was not an expected  result. Furthermore, two different experiments found the same statistical anomaly - an unexpected decay channel of a pair of high energy photons at 750GeV - that may indicate additional Higgs particles at higher masses.

Next is the big question of particle physics - dark matter. When a quarter of the universe is composed of some kind of particle you can neither identify nor describe, that's a question that has to be answered. Essentially, dark matter is composed of some unknown particle that has mass but does not interact with 'regular' baryonic matter. There are a number of proposed explanations - particularly SuperSymmetry, or SUSY, which postulates each particle in the Standard Model has a 'Superpartner' at a higher mass. Physicists hope that at the higher energies and greater luminosity of the LHC this year they'll begin to see some of those higher mass particles.

And, of course, there's always the possibility of something totally unexpected. This years run is a little like walking into a vast dark warehouse for the first time with a flashlight. These energies and these collision rates will take our species to a place that hasn't even existed in almost 14 billion years. What will be observed will be nothing more than what nature has always incorporated, perhaps things that other species have observed before, but we will be seeing them for the very first time. Confirming and validating existing theories is great, and necessary scientific work, but everyone greatly prefers seeing data that forces them to tear up the old theories and start over. THAT'S when this gets truly exciting.

1 comment:

  1. I immensely enjoyed the November lecture by Dr Kyle Cranmer of NYU on the 'post Higgs LHC'. You should check to see if there are any groups giving science lectures at bars in the Bay Area. I think they'd be a smash success.