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Two circulating beams bring first collisions in the LHC

Posted: Mon Nov 23, 2009 5:33 pm
by fjgiie

Re: Big Bang Day

Posted: Tue Nov 24, 2009 11:29 am
by jsmaje
Fingers (and beams) crossed this time!

Re: Big Bang Day

Posted: Sun Apr 11, 2010 12:44 pm
by jsmaje
Better late than never (both this post and the LHC success on 30 March 2010 itself): Large Hadron Collider Smashes Protons, Sets Record. Congratulations to all involved :D .

Sadly they were beaten to it: Ten Year Old Makes Functioning Mini Hadron Collider in Bedroom.
Nevertheless, the LHC has in fact produced its first tangible result: Man arrested at Large Hadron Collider claims he's from the future.

Meanwhile, I've discovered that the 7 TeV energy of the proton collisions is in fact equivalent to no more than the combined kinetic energy of 7 flying mosquitos (1 TeV each) - and this according to CERN themselves!
Of course a mosquito is squillions of times larger than a proton, so I presume the energy involved has more oomph when concentrated into such a small diameter as a proton (by the way, while having mass, do protons actually have a measureable diameter in the quantum mechanical sense?)
Whatever, this puts into perspective the scare stories about forming troublesomely-heavy black holes, at least as long as Stephen Hawking is correct that small ones on this sort of scale will rapidly evaporate.

I must brag that I had the priviledge to meet the great man on Feb 27 this year in Cambridge UK, where he was presented with the "Cosmos Award for Outstanding Public Presentation of Science" by the Planetary Society (where Ann Druyan, Carl Sagan's widow, and Martin Rees, 'Astronomer Royal' were also amongst several fascinating contributors at the meeting).
I passed on a letter from a good friend of mine, whose uncle Prof. Robert Berman was Hawking's tutor when an undergraduate at University College in Oxford, and taught him all the physics he knew - at least up until then!
I must add that neither I nor my friend are physicists.


Re: Big Bang Day

Posted: Wed Jul 07, 2010 1:24 pm
by jsmaje
I hardly understand a word of this latest bulletin from CERN, but it sounds good: A new record peak luminosity for the LHC.

The 'inverse femptobarn' unit was new to me; here's an excerpt from Wikipedia's explanation:
  • The etymology of the unit 'barn' is clearly whimsical and jocular. During wartime research on the atomic bomb, American physicists who were deflecting neutrons off uranium nuclei, (similar to Rutherford scattering) described the uranium nucleus as "big as a barn." Physicists working on the project adopted the name 'barn' for a unit equal to 10^-24 square centimetres, about the size of a uranium nucleus. Initially they hoped the American slang name would obscure any reference to the study of nuclear structure; eventually, the word became a standard unit in particle physics.

    The 'inverse femtobarn' (fb^-1) is a measurement of particle collision events per femtobarn. Over a period of time, two streams of particles with a cross-sectional area, measured in femtobarns, are directed to collide. The total number of collisions is directly proportional to the luminosity of the collisions measured over this time. Therefore, the collision count can be calculated by multiplying the integrated luminosity by the sum of the cross-section for those collision processes. This count is then expressed as inverse femtobarns for the time period (e.g., 100 fb^-1 in 9 months). Inverse femtobarns are often quoted as an indication of particle collider effectiveness.

    It took Fermilab over a decade to achieve 1 fb^-1
The aim at the LHC is to reach its first fb^-1 in 10 months.