Sunday July 25, 2004

Inverse Femtobarns

Rich and I have learned a new unit of measurement - the inverse femtobarn.

What on earth is a "femtobarn," and what does it have to do with the amount of data an accelerator produces?

Rich picked up a copy of the Stanford Report, a daily Stanford newspaper. In the paper was an article entitled Understanding luminosity through 'barn', a unit that helps physicists count particle events.

A barn is the unit used by nuclear physicist for the size of an atomic nucleus of uranium.

The cross-sectional area of a uranium nucleus is about 10 -24 square centimeters, small on the human scale, but large compared with other atomic nuclei. "Femto" means a factor of 10-15: a thousandth of a millionth of a millionth. A femtobarn, then, is 10-39 square centimeters ­ an incomprehensibly small unit of area.

The term "barn" was coined by two physicists, M. G. Holloway and C. P. Parker, at Purdue University in December, 1942. ...
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Inverse Femtobarns ( in category SciTech ) - posted at Sun, 25 Jul, 20:58 Pacific