Fine Structure

Less than a full sentence into Dorigo's recent article on new data from the Higgs search I realized that I needed to learn the definition of a femtobarn. Googling, I found a link to a great glossary of nuclear physics terms and their inceptions. Referring to the luminosity of a collider, a femtobarn is:

A unit of cross section equal to 10^-39 cm², more or less equivalent to the physical cross-sectional area of a typical nucleus.

And that really says something if your collider can't hit the broad side of a femtobarn. I've seen it used interchangeably between the formats "1.6/fb" or "1.6 inverse femtobarns" (perhaps I don't quite understand the purposes of the two formats, it's particularly confusing for a novice physicist though). http://www.orau.org/ptp/articlesstories/names.htm#barn