Más sobre el LHC. Fascinante.

Sobre el LHC Brochure del CERN en espanol
El LHC está instalado en un túnel de 27 km de circunferencia, a una profundidad que oscila entre los 50 y los 150 m. Este túnel, situado entre la cordillera del Jura, en Francia, y el Lago Ginebra, en Suiza, se construyó en la década de 1980 para alojar el acelerador anterior, el Gran Colisionador Electrón-Positrón (LEP, de sus siglas en inglés).
El LHC provocará colisiones frontales entre dos haces de partículas del mismo tipo, o bien protones o bien iones de plomo. Los haces se crearán en una cadena de aceleradores que ya existe en el CERN, y después se inyectarán en el LHC, donde se moverán en un vacío comparable al del espacio sideral. Los imanes superconductores, que funcionan a temperaturas extremadamente bajas, guiarán los haces alrededor del anillo.
Cada haz estará formado por unos 3.000 paquetes de partículas, y cada paquete contendrá unos 100.000 millones de partículas. Las partículas son tan pequeñas que la probabilidad de que dos de ellas choquen es muy pequeña. Cuando dos haces se crucen, sólo se producirán unas 20 colisiones entre los 200.000 millones de partículas. Sin embargo,como los haces se cruzarán unos 30millones de veces por segundo, el LHC generará hasta 600millones de colisiones por segundo.

Cuando se ponga en marcha, el LHC provocará las colisiones más energéticas que jamás sehayan producido en un laboratorio. Los físicos están ansiosos por saber qué revelarán estas colisiones,que se registrarán con cuatro inmensos detectores: ALICE, ATLAS, CMS y LHCb. Con ellos, los físicos quieren investigar nuevos fenómenos relacionados con la materia, la energía, el espacio y el tiempo.


Un protón del LHC,
que se moverá a casi la velocidad
de la luz, dará 11.245
vueltas por segundo. Un haz circulará
hasta 10 horas seguidas, en las
cuales recorrerá 10.000 millones de
kilómetros, una distancia equivalente
a ir hasta el planeta Neptuno
y volver.

FAQ and Facts about the LHC

Recomiendo la lectura de este Op-Ed en el New York Times, explica claramente lo que se busca con el LHC.

Brian Greene: A Crash Course on the Origins of the Universe
After a decade in the works, the Large Hadron Collider was switched on this week. What can we expect?

La nota en el CERN

“It’s a fantastic moment,” said LHC project leader Lyn Evans, “we can now look forward to a new era of understanding about the origins and evolution of the universe.”

First beam in the LHC - accelerating science
Geneva, 10 September 2008. The first beam in the Large Hadron Collider at CERN was successfully steered around the full 27 kilometres of the world’s most powerful particle accelerator at 10h28 this morning. This historic event marks a key moment in the transition from over two decades of preparation to a new era of scientific discovery.


What will be the Higgs boson production rate at the LHC?
Although the particle collision rate at the LHC will be very high, the production rate of the Higgs will be so small that physicists expect to have enough statistics only after about 2-3 years of data-taking.The Higgs boson production rate strongly depends on the theoretical model and calculations used to evaluate it. Under good conditions,there is expected to be about one every few hours per experiment.
The same applies to supersymmetric particles. Physicists expect to have the first meaningful results in about one year of data-taking at full luminosity.


Are the LHC collisions dangerous?

The LHC can achieve energies that no other particle accelerators have reached before. The energy of its particle collisions has previously only been found in Nature. And it is only by using such a powerful machine that physicists can probe deeper into the key mysteries of the Universe. Some people have expressed concerns about the safety of whatever may be created in high-energy particle collisions. However there are no reasons for concern.

} Unprecedented energy collisions? On Earth only! Accelerators only recreate the natural phenomena of cosmic rays under controlled laboratory conditions. Cosmic rays are particles produced in outer space in events such as supernovae or the formation of black holes, during which they can be accelerated to energies far exceeding those of the LHC. Cosmic rays travel throughout the Universe, and have been bombarding the Earth’s atmosphere continually since its formation 4.5 billion years ago. Despite the impressive power of the LHC in comparison with other accelerators, the energies produced in its collisions are greatly exceeded by those found in some cosmic rays. Since the much higher-energy collisions provided by nature for billions of years have not harmed the Earth, there is no reason to think that any phenomenon produced by the LHC will do so. Cosmic rays also collide with the Moon, Jupiter, the Sun and other astronomical bodies. The total number of these collisions is huge compared to what is expected at the LHC. The fact that planets and stars remain intact strengthens our confidence that LHC collisions aresafe. The LHC’s energy, although powerful for an accelerator, is modest by nature’s standards.

} Mini big bangs? Although the energy concentration (or density)in the particle collisions at the LHC is very high, in absolute terms the energy involved is very low compared to the energies we deal with every day or with the energies involved in the collisions of cosmic rays. However, at the very small scales of the proton beam, this energy concentration reproduces the energy density that existed just a few moments after the BigBang—that is why collisions at the LHC are sometimes referred to as mini big bangs.


} Black holes? Massive black holes are created in the Universe by
the collapse of massive stars, which contain enormous amounts
of gravitational energy that pulls in surrounding matter. The
gravitational pull of a black hole is related to the amount of
matter or energy it contains — the less there is, the weaker
the pull. Some physicists suggest that microscopic black holes
could be produced in the collisions at the LHC. However, these
would only be created with the energies of the colliding particles
(equivalent to the energies of mosquitoes), so no microscopic
black holes produced inside the LHC could generate a
strong enough gravitational force to pull in surrounding matter.
If the LHC can produce microscopic black holes, cosmic rays of
much higher energies would already have produced many more.
Since the Earth is still here, there is no reason to believe that
collisions inside the LHC are harmful.
Black holes lose matter through the emission of energy via a
process discovered by Stephen Hawking. Any black hole that cannot
attract matter, such as those that might be produced at the
LHC, will shrink, evaporate and disappear. The smaller the black
hole, the faster it vanishes. If microscopic black holes were to be
found at the LHC, they would exist only for a fleeting moment.
They would be so short-lived that the only way they could be
detected would be by detecting the products of their decay.

Más en el FAQ and Facts Brochure


10 Fascinating Facts about the LHC
Fact 1) When the 27-km long circular tunnel was excavated, between Lake
Geneva and the Jura mountain range, the two ends met up to within 1 cm.
Fact 2) Each of the 6400 superconducting filaments of niobium–titanium
in the cable produced for the LHC is about 0.007 mm thick, about 10 times
thinner than a normal human hair. If you added all the filaments together
they would stretch to the Sun and back five times with enough left over for
a few trips to the Moon.
Fact 3) All protons accelerated at CERN are obtained from standard hydrogen.
Although proton beams at the LHC are very intense, only 2 nanograms
of hydrogen(*) are accelerated each day. Therefore, it would take the LHC
about 1 million years to accelerate 1 gram of hydrogen.
Fact 4) The central part of the LHC will be the world’s largest fridge. At a
temperature colder than deep outer space, it will contain iron, steel and the
all important superconducting coils.
Fact 5 ) The pressure in the beam pipes of the LHC will be about ten times
lower than on the Moon. This is an ultrahigh vacuum.
Fact 6) Protons at full energy in the LHC will be travelling at 0.999999991
times the speed of light. Each proton will go round the 27 km ring more than
11 000 times a second.
Fact 7) At full energy, each of the two proton beams in the LHC will have a
total energy equivalent to a 400 t train (like the French TGV) travelling at
150 km/h. This is enough energy to melt 500 kg of copper.
Fact 8) The Sun never sets on the ATLAS collaboration. Scientists working on
the experiment come from every continent in the world, except Antarctica.
Fact 9) The CMS magnet system contains about 10 000 t of iron, which is
more iron than in the Eiffel Tower.
Fact 10) The data recorded by each of the big experiments at the LHC will
be enough to fill around 100 000 DVDs every year.
(*)the total mass of protons is calculated at rest.

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