Re: [Brahms-l] Physics News Update 728 (fwd)

Hi Flemming,

I also just saw this web page through the email.

Maybe someone could ask them to update the picture then. The picture you 
pointed me to looks very nice;)

Here is another place that might need it (even though Allan might be proud 
of the one that's there now:)
http://www.bnl.gov/RHIC/BRAHMS.htm
Visual representation of the data output from the BRAHMS detector during 
the first gold ion collisions at RHIC.
=>
Visual representation of the data output from the BRAHMS detector of a 
gold ion collisions at RHIC.

Cheers,
   Peter

On Thu, 21 Apr 2005, flemming videbaek wrote:

> Hi Peter,
> I have actually not know about this web page. I general we now point to the
> pictures of events that are much nice  e.g.
> http://server.c-ad.bnl.gov/esfd/RMEM/event_brahms.GIF
> which I think is much better.
> 
> regards
>     Flemming
> 
> ----------------------------------------------------------------
> Flemming Videbaek
> Physics Department
> Brookhaven National Laboratory
> 
> e-mail: videbaek@bnl.gov
> phone: 631-344-4106
> ----- Original Message ----- 
> From: "Peter H.L. Christiansen" <pchristi@nbi.dk>
> To: "brahms-l" <brahms-l@lists.bnl.gov>
> Sent: Thursday, April 21, 2005 3:31 AM
> Subject: [Brahms-l] Physics News Update 728 (fwd)
> 
> 
> > Hi,
> >
> > A long story about the RHIC whitepapers in the Physics News Update. Maybe
> > we could change the picture on the web page for BRAHMS to resemble
> > something a bit more Hubble quality like;)
> >
> > Cheers,
> >    Peter
> >
> > -- 
> > :-) --------------------------- )-:
> >  Peter H L Christiansen
> >  pchristi@nbi.dk / (+41)764870425
> > :-D --------------------------- \-:
> >
> > ---------- Forwarded message ----------
> > Date: Wed, 20 Apr 2005 10:42:37 -0400
> > From: physnews@aip.org
> > To: pchristi@NBI.DK
> > Subject: Physics News Update 728
> >
> > PHYSICS NEWS UPDATE
> > The American Institute of Physics Bulletin of Physics News
> > Number 728 April 20, 2005  by Phillip F. Schewe, Ben Stein
> >
> > AN OCEAN OF QUARKS.  Nuclear physicists have now demonstrated that
> > the material essence of the universe at a time mere microseconds
> > after the big bang consists of a ubiquitous quark-gluon liquid.
> > This huge insight comes from an experiment carried out over the past
> > five years at the Relativistic Heavy Ion Collider (RHIC), the giant
> > crusher of nuclei located at Brookhaven National Lab, where
> > scientists have created a toy version of the cosmos amid high-energy
> > collisions.  RHIC is of course not a telescope pointed at the sky
> > but an underground accelerator on Long Island; it is, nevertheless,
> > in effect, a precision cosmology instrument for viewing a very early
> > portion of the universe, a wild era long before the time of the
> > first atoms (which formed about 400,000 years after the big bang),
> > before the first compound nuclei such as helium (about a minute
> > after the big bang), before even the time when protons are thought
> > to have formed into stable entities (ten microseconds).
> >
> > In our later, cooler epoch quarks conventionally occur in groups of
> > two or three.  These groupings, called mesons and baryons,
> > respectively, are held together by particles called gluons---which
> > act as agents for the strong nuclear force.  Baryons (such as
> > protons and neutrons), collectively called hadrons, are the normal
> > building blocks of any nucleus.  Could hadrons be melted or smashed
> > into their component quarks through violent means?  Could a nucleus
> > be made to rupture and spill its innards into a common swarm of
> > unconfined quarks and gluons?  This is what RHIC set out to show.
> >
> > Let's look at what happened.  In the RHIC accelerator itself two
> > beams of gold ions, atoms stripped of all their electrons, are
> > clashed at several interaction zones around the ring-shaped
> > facility.  Every nucleus is a bundle of 197 protons and neutrons,
> > each of which shoots along with an energy of up to 100 GeV.
> > Therefore, when the two gold projectiles meet in a head-on "central
> > collision" event, the total collision energy is 40 TeV (40 trillion
> > electron volts).  Of this, typically 25 TeV serves as a stock of
> > surplus energy---call it a fireball---out of which new particles can
> > be created.   Indeed in many gold-gold smashups as many as 10,000
> > new particles are born of that fireball.  Hubble-quality pictures of
> > this blast of particles
> > (http://www.bnl.gov/RHIC/full_en_images.htm), shows the aftermath of
> > the fireball, but not the fireball itself.
> >
> > The outward streaming particles provide all the forensic evidence
> > for determining the properties of the fireball.  To harvest this
> > debris, the RHIC detectors must be agile and very fast. The
> > recreation of the frenzied quark era is ephemeral, lasting only a
> > few times 10^-24 seconds. The size of the fireball is about 5
> > femtometers, its density about 100 times that of an ordinary
> > nucleus, and its temperature about 2 trillion degrees Kelvin or (in
> > energy units) 175 MeV.  RHIC was built to create that fireball.  But
> > was it the much-anticipated quark-gluon plasma?  The data
> > unexpectedly showed that the fireball looked nothing like a gas.
> > For one thing, potent jets of mesons and protons expected to be
> > squirting out of the fireball, were being suppressed.
> >
> > Now, for the first time since starting nuclear collisions at RHIC in
> > the year 2000 and with plenty of data in hand, all four detector
> > groups operating at the lab have converged on a consensus opinion.
> > They believe that the fireball is a liquid of strongly interacting
> > quarks and gluons rather than a gas of weakly interacting quarks and
> > gluons.  The RHIC findings were reported at this week's April
> > meeting of the American Physical Society (APS) in Tampa, Florida in
> > a talk delivered by Gary Westfall (Michigan State) and at a press
> > conference attended by several RHIC scientists.
> >
> > Brookhaven physicist Samuel Aronson said that having established the
> > quark-gluon-liquid nature of the pre-protonic universe, RHIC
> > expected to plumb the liquid's properties, such as its heat capacity
> > and its reaction to shock waves.  The liquid is dense but seems to
> > flow with very little viscosity.  It flows so freely that it
> > approximates an ideal, or perfect, fluid, the kind governed by the
> > standard laws of hydrodynamics.  At least in its flow properties the
> > quark liquid is therefore a classical liquid and should not be
> > confused with a superfluid, whose flow properties (including zero
> > viscosity) are dictated by quantum mechanics.
> >
> > One of the reasons for RHIC's previous hesitancy in delivering a
> > definitive pronouncement was concern over the issue of whether the
> > observed nuclear liquid was composed of truly deconfined quarks and
> > gluons or of quarks confined within hadrons, or maybe even a mixture
> > of quarks and hadrons.  According to William Zajc (Columbia Univ.
> > and spokesperson for the PHENIX detector group at RHIC), the
> > patterns of particles flying out of the fireball, including
> > preliminary data on heavier, charm-quark-containing particles such
> > as D mesons, support the quark liquid picture.
> >
> > To summarize, the main stories here are (1) that based on the
> > evidence of the RHIC data, the universe in the microsecond era would
> > seem to consist of a novel liquid of quarks and gluons; (2) that
> > RHIC has reproduced small fragments of this early phase of the
> > universe for detailed study; and (3) that these results are vouched
> > for by all four RHIC groups.  If there had been delays in making an
> > announcement of the results or if the exact nomenclature for the
> > novel nuclear matter had been left unsettled, the RHIC physicists at
> > the press conference seemed more interested in pursuing their new
> > kind of experimental science---a sort of fluid-dynamical cosmology.
> >
> > (All four groups are also concurrently publishing  "white paper"
> > summaries of their work in the journal Nuclear Physics A.  Preprints
> > are available as follows: BRAHMS,
> > http://arxiv.org/abs/nucl-ex/0410020 ; PHENIX,
> > http://arxiv.org/abs/nucl-ex/0410003 ; PHOBOS,
> > http://arxiv.org/abs/nucl-ex/0410022 ; and STAR,
> > http://arxiv.org/abs/nucl-ex/0501009)
> >
> > ***********
> > PHYSICS NEWS UPDATE is a digest of physics news items arising
> > from physics meetings, physics journals, newspapers and
> > magazines, and other news sources.  It is provided free of charge
> > as a way of broadly disseminating information about physics and
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> > Physics News Update appears approximately once a week.
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-- 
:-) --------------------------- )-:
 Peter H L Christiansen
 pchristi@nbi.dk / (+41)764870425
:-D --------------------------- \-:


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