Over the weekend the LHC was able to deliver our first pb^-1 of data! Milestones keep rolling on by and the data keeps rolling in. This is a big first step in getting what will hopefully be lots and lots of data. I’ve included a link to the ATLAS luminosity plot for your viewing pleasure. (CMS has one too… but I’m on ATLAS )
To anyone who isn’t a particle physicist an inverse picobarn (pb^-1) is a pretty bizarre unit. I’ll start out with the base unit: the barn (b). It’s a measurement of area, proportional to m^2 or cm^2. The barn unit comes from when nuclear physics was in its infancy and refers to a uranium nucleus which is as big as a barn (1 barn = 10^-24 cm^2). (I still think physicists should hire writers to come up with this stuff… anywho, back to the post).
An inverse barn (or b^-1) in the particle physics world is a measure of collision events in an area of a barn. Throw in a metric prefix (pico which is 10^-12*base unit) and now you’re all caught up to speed. But what does that mean really? Fermilab has over an inverse femtobarn (fb^-1, which means 1000x an inverse picobarn) of data but of course they’ve been running their collider for over a decade. We’ll still need much more data to do searches for things like the Higgs, but very early searches are definitely underway – not to mention all the Standard Model physics and calibration that’s going on too.
So cheers to the first pb-1 of data… I can’t wait to start analyzing.