During Christmas holidays I tend to indulge in online chess playing a bit too much, wasting several...

Why Measure The Top Quark Production Cross Section?

As part of my self-celebrations for XX years of blogging activities, I am reposting here (very)...

The Buried Lottery

As part of my self-celebrations for having survived 20 years of blogging (the anniversary was a...

Twenty Years Blogging

Twenty years ago today I got access for the first time to the interface that allowed me to publish...

Tommaso Dorigo

Tommaso Dorigo is an experimental particle physicist, who works for the INFN at the University of Padova, and collaborates with the CMS and the SWGO experiments. He is the president of the Read More »

Pictures Of A Giant Marvel

Nov 12 2009 | comment(s)

Today I got access to a collection of very cool pictures of the CMS detector, one of the two experiments designed and built to study proton-proton collisions delivered by the Large Hadron Collider at CERN.

Many of those pictures, which were taken by Michael Hoch (CERN/CMS) in the last couple of years, have circulated in the web for a long time, and individual ones have been used in several places. However, they are very nice to browse one after the other. And I think they are even more interesting to watch if one has not had the privilege of visiting the giant detector in its underground cavern, during its assembly last year. So I take the liberty of showing them to you here, in case you missed them - or just like to refresh your memory on this technological marvel.

Count to five: a child has died from hunger

Nov 11 2009 | comment(s)

Please visit this site, and watch a ten seconds video which is very aggressive in its crude substance: during the time you watch it, two children die of hunger.

There are in the world today a billion human beings who have insufficient means to sustain themselves, their families, their children. This is so intolerable that we use to remove it from our brain. Can you imagine your child dying of hunger as you watch powerless ?

What is going on around

Nov 09 2009 | comment(s)

Today, having little inspiration to write anything original myself, I decided to have a look at what other sites held by colleagues or friends are dealing with. I offer below a few interesting links, with minimal commentary.

Peter Woit is always more informed than anybody else, with more precise data available earlier than anywhere else, on the status of the LHC project. I advise you to keep an eye on his blog in the near future.

Why Physicists Like Ratios

Nov 08 2009 | comment(s)

A good part of basic research in fundamental physics focuses on the definition, the prediction, and the measurement of quantities which put the current theory -the standard model- to the test in the most stringent way possible. The choice of the quantities on which to base our comparisons between theory prediction and measurement is critical: it entails understanding what may make the comparison imprecise (i.e. experimental systematics affecting the measurement) or fruitless (i.e. theoretical assumptions or a bad definition of the quantity to measure).

One clear example, which I used last week in my lessons of Subnuclear Physics to undergraduates in Padova, is the measurement of the W and Z boson cross sections at the Tevatron proton-antiproton collider.

The Say of the Week: Lederman's Shoulder

Nov 05 2009 | comment(s)

"The yield of muon pairs decreased rapidly from 1 GeV to the kinematic limit of nearly 6 GeV with the exception of a curious shoulder near 3GeV. The measurement of muons was by range as determined by liquid and plastic scintillation counters interspersed with steel shielding. Each angular bin (there were 18) had four range bins, and for two muons this made a total of only 5000 mass bins into which to sort the data. Multiple scattering in the minimum of 10 feet of steel
made finer binning useless. Thus we could only note that "Indeed, in the mass region near 3.5 GeV, the observed spectrum may be reproduced by a composite of a resonance and a steeper continuum." This 1968-1969 experiment was repeated in 1974 by Aubert et al. (1974), with a

Learn To Compute Higgs Limits On The Fly

Nov 04 2009 | comment(s)

I am presently into the second week of my lessons of Subnuclear Physics for the 2nd year of specialization in Physics, and I have just finished a lesson discussing the current searches for the Higgs boson at the Tevatron collider. Since the course has a focus on experimental techniques, I found it useful today to give as an exercise the determination of an order-of-magnitude estimate of cross section limits that the CDF experiments can set on a 160 GeV Higgs boson, with the data so far analyzed. It is an exercise I worked out by heart during my walk to the Physics Department: this should tell you it is not of overpowering difficulty.