LHC News

[EarthlingX]

physicsworld.com : LHC sees its first ZZ event

Nov 11, 2010

The Large Hadron Collider (LHC) at CERN in Geneva has produced its first pair of Z bosons, based on data released by the compact muon solenoid (CMS) collaboration. Seeing this first pair is an important step in the giant collider's hunt for the Higgs boson because the generation and analysis of many more such events could provide one of the key signatures of the elusive Higgs.


A quartet of muons flying through CMS

Believed to provide all particles with mass, the Higgs boson is the last missing piece of the Standard Model of particle physics. The LHC, designed to collide protons into one another at energies of up to 14 TeV, is expected to find the elusive boson – assuming that the Higgs does indeed exist.

Evidence for the Higgs will not come as a single observation. Instead, physicists must accumulate data related to the energy distribution of the particles that the Higgs decays into. One of the cleanest such decay signatures is the transformation of the Higgs into two Z bosons – particles that are one of the carriers of the weak nuclear force. The Z bosons then decay into pairs of heavy charged particles known as muons, which leave an unmistakable footprint in a detector such as CMS.

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[EarthlingX]

[youtube]http://www.youtube.com/watch?v=jwrFwcqa4UI[/youtube]

CERNTV | November 15, 2010

The LHC runs led ions for the first time, reaching unprecedented collision energy

 

[EarthlingX]

press.web.cern.ch : Antimatter atoms produced and trapped at CERN

17.11.2010

Geneva, 17 November 2011. The ALPHA experiment at CERN1 has taken an important step forward in developing techniques to understand one of the Universe’s open questions: is there a difference between matter and antimatter? In a paper published in Nature today, the collaboration shows that it has successfully produced and trapped atoms of antihydrogen. This development opens the path to new ways of making detailed measurements of antihydrogen, which will in turn allow scientists to compare matter and antimatter.

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In another recent development in CERN’s antimatter programme, the ASACUSA experiment has demonstrated a new technique for producing antihydrogen atoms. In a paper soon to appear in Physical Review Letters, the collaboration reports success in producing antihydrogen in a so-called Cusp trap, an essential precursor to making a beam. ASACUSA plans to develop this technique to the point at which beams of sufficient intensity will survive for long enough to be studied.

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* For further information on ALPHA experiment, please read here: http://cerncourier.com/cws/article/cern/30577
* Pictures available here: http://cdsweb.cern.ch/record/1307522
* Footage available here: http://cdsweb.cern.ch/record/1307524

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[EarthlingX]

http://www.symmetrymagazine.org : ALICE experiment announces first results from LHC’s lead-ion collisions

November 18, 2010 | 5:50 am


One of the first collisions of lead ions as recorded by the ALICE detector on November 8, 2010.

Scientists from the ALICE experiment at CERN’s Large Hadron Collider have publicly revealed the first measurements from the world’s highest energy heavy-ion collisions. In two papers posted today to the arXiv.org website, the collaboration describes two characteristics of the collisions: the number of particles produced from the most head-on collisions; and, for more glancing blows, the flow of the system of two colliding nuclei.

Both measurements serve to rule out some theories about how the universe behaves at its most fundamental, despite being based on a relatively small number of collisions collected in the first few days of LHC running with lead-ion beams.

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arxiv.org : Elliptic flow of charged particles in Pb-Pb collisions at 2.76 TeV

Authors: The ALICE Collaboration
(Submitted on 17 Nov 2010)

Abstract: We report the first measurement of charged particle elliptic flow in Pb-Pb collisions at 2.76 TeV with the ALICE detector at the CERN Large Hadron Collider. The measurement is performed in the central pseudorapidity region (|eta|<0.8) and transverse momentum range 0.2< p_t< 5.0 GeV/c. The elliptic flow signal v_2, measured using the 4-particle correlation method, averaged over transverse momentum and pseudorapidity is 0.087 +/- 0.002 (stat) +/- 0.004 (syst) in the 40-50% centrality class. The differential elliptic flow v_2(p_t) reaches a maximum of 0.2 near p_t = 3 GeV/c. Compared to RHIC Au-Au collisions at 200 GeV, the elliptic flow increases by about 30%. Some hydrodynamic model predictions which include viscous corrections are in agreement with the observed increase.

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arxiv.org : Charged-particle multiplicity density at mid-rapidity in central Pb-Pb collisions at sqrt(sNN) = 2.76 TeV

Authors: The ALICE Collaboration
(Submitted on 17 Nov 2010)

Abstract: The first measurement of the charged-particle multiplicity density at mid-rapidity in Pb-Pb collisions at a centre-of-mass energy per nucleon pair sqrt(sNN) = 2.76 TeV is presented. For an event sample corresponding to the most central 5% of the hadronic cross section the pseudo-rapidity density of primary charged particles at mid-rapidity is 1584 +- 4 (stat) +- 76 (sys.), which corresponds to 8.3 +- 0.4 (sys.) per participating nucleon pair. This represents an increase of about a factor 1.9 relative to pp collisions at similar collision energies, and about a factor 2.2 to central Au-Au collisions at sqrt(sNN) = 0.2 TeV. This measurement provides the first experimental constraint for models of nucleus-nucleus collisions at LHC energies

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[Lamellar11]

Golly gee, folks. This all appears quite complicated -- my calculator isn't very good. Sentimentally, I choose the simplist return for the ultimate goal -- whether we use the LHC or some other bigger, or better device, what power will be the safest to harness and allow what most would consider the ultimate goal -- faster than light speed and what truly happens when it is reached? Then, how can we reach it; and can we do it safely (can we physically (not just our DNA) survive a trip from here to there)? Proving that Higgs boson exists and the properties of dark matter, as well as, all the other really fun things attributed to theory, are only a steps on a steep stairway to the ultimate goal--traveling as fast as possible, to get wherever we can to prove or disprove the existance of God the Creator. Naturally, we all want to know how it was done; when it was done; and do we need God to do it, or can we do it ourselves? There's no place like home but also, there's no place like being somewhere else.

 

[MeteorWayne]

Lamellar11,
Welcome to Space.com.

Since your post has very little or nothing to do with the Physics forum, or the subject of this discussion, it might be moved.

I'd strongly suggest you spend a bit of time reading the fora to get a feel for what gets discussed where, and please read the Community Guidelines.

Wayne

 

[MeteorWayne]

Early Universe a super hot liquid?

ALICE results.

Be forewarned, this is a NewScientist article, so is usually in the bottom quartile of what the journal articles actually say...I don't have time to read them now before heading up to the observatory.

http://www.newscientist.com/article/dn1 ... print=true

Journal Links:

http://arxiv.org/abs/1011.3914

http://arxiv.org/abs/1011.3916