After 10 years of careful analysis and scrutiny, scientists of the CDF collaboration at the U.S. Department of Energy's Fermi National Accelerator Laboratory announced today that they have achieved the most precise measurement to date of the mass of the W boson, one of nature's force-carrying particles. Using data collected by the Collider Detector at Fermilab, or CDF, scientists have now determined the particle's mass with a precision of 0.01%—twice as precise as the previous best measurement. It corresponds to measuring the weight of an 800-pound gorilla to 1.5 ounces.