We are on. This afternoon just after 1PM the LHC beams have started to produce proton-proton collisions in the heart of the experiments, at the never-before achieved energy of 7 TeV.

It was a long journey to get here -the project is twenty years old- but this is just the start of a new, more exciting one: In the course of the next two years, the Large Hadron Collider will gradually increase its power, allowing the CMS and ATLAS detectors to collect enough data to significantly extend into discovery territory.

Marco Silva (right) is an amateur astronomer since the 1997 Hale-Bopp comet passage. He is also an amateur scientist. His studies can be found in his web site. When I knew of his interesting measurements of cataclysmic variable stars, I invited him to write about the matter for us here....

Cataclysmic Variables

The number in the title, interpreted in units per square centimeters per second, is a flux rate, and it is a new world record set by the Tevatron collider last night on the number of protons and antiprotons forced to cross each other within a tiny interaction region in the core of the CDF and DZERO experiments.

It makes me very happy when I see new precise results on the mass of the top quark being produced by the CDF collaboration (to which I still proudly belong). CDF, one of the two hadron collider experiments operating at the 2-TeV Tevatron proton-antiproton synchrotron in Batavia, IL, has been measuring the top quark mass since 1994, one year prior to its discovery. The figure with the top candidates (histogram) from which the mass measurement of 174+-12 GeV was obtained in 1994 is shown on the right below; backgrounds and top expectation are shown by hatched lines.