In order to be able to perform unescorted access to areas where ionizing radiations are present, and to work with and use radioactive materials, workers at Fermilab have to pass a specific training which enables them to recognize the dangers and work safely, minimizing the radiation dose they get by performing their activities, and reducing the spread of contamination to the environment.
Fermilab is a wonderful place to travel to in the late summer or fall. The site of the laboratory is a wide chunk of land just east of the Fox river, 30 miles west of Chicago. It is home to not just physicists and engineers, but to a wide variety of animals. Geese on their way South stop yearly in the lake in front of Fermilab's Wilson Hall, and many of them decide to spend the winter there, to benefit from the warm waters; deer are copious, but will not be easily seen around, save for the occasional one at times seen standing in the middle of the road at night; buffalos roam within large lots of land outside and inside the ring. Woods, trees with widely varied colours, and prairie make one feel it is a privilege to do Science there.
What happened to all the enthusiasm? Perhaps new astronomy will shed light on the matter. In 2005 the anniversary of Einstein's miracle year there was much talk of "new Einstien"s and why there have been no new ones. Carlo Rovelli published a very good book on the subject. String theory and M theory were as hot as the surface of the sun. In a heated exchange on Wikipedia I made the acquaintance of Lubos Motl. There was much excitement 4 years ago. So what happened? Why no accepted theory of quantum gravity?
Today I wish to bring to your attention a figure recently obtained by the CDF collaboration, one which really tells a thousand words. Before I describe it to you, however, I would like to discuss at an elementary level a few basic concepts of particle theory which the figure well summarizes.
A Crash Course on Feynman Graphs
Let us start with a few elements on Feynman graphs -the diagrams that physicists use to draw on their blackboards to picture what really happens when particles react, and that actually enable the computation of the probability of those processes.
The slide below was shown yesterday at an invited talk that Antonio Masiero gave in the University of Bologna, during an open session of the CMS Physics week (see, I am careful to note I am not breaking any rules by showing material relevant to internal CMS business: the session was open!).
The CDF collaboration has recently released a study of the production of pairs of W bosons in a large bounty of proton-antiproton collisions produced by the Tevatron collider -3.6 inverse femtobarns of them, or roughly 300 trillions, give or take 6%.
The measurement of the production cross section of this clean and rare electroweak process (its absolute rate, that is) is the most precise ever obtained so far, and reaches down to a level of uncertainty which cannot be improved further significantly at the Tevatron, because it is now limited by the uncertainty in the overall integrated luminosity mentioned above.
Sometimes I come to think this blog is overextended: it happens when I realize it contains more things than I can remember, even ones I would really like to have at my fingertips. I was reminded yesterday of a very funny story which a reader left in the comments thread of a rather meaningless post, and decided I should make a separate post of it, since it made my day reading it and it might make yours too...
The story was told by Leon Lederman in an introduction to Carlo Rubbia in the proceedings of a conference held in 1984 in Santa Fe:
"... Now I have some interesting news, a story that is at the least
apocryphal. It concerns the heroic contestant in one of those ancient
trials by strength which are so natural for our "Carlo". This trial was