by Katia Moskvitch

Science reporter, BBC News

3 November 2010
from BBC Website

 

 

 

 


Simulated lead-lead collision

The ALICE experiment has been designed for lead ions collisions (simulation)
 

 

 

Researchers at the Large Hadron Collider (LHC) are getting set to create the Big Bang on a miniature scale.

Since 2009, the world's highest-energy particle accelerator has been smashing together protons, in a bid to shed light on the fundamental nature of matter.

But now the huge machine will be colliding lead ions instead.

The experiments are planned for early November and will run for four weeks. The LHC is housed in a 27km-long tunnel on the Franco-Swiss border and is managed by the European Organization for Nuclear Research (CERN).

The collider consists of four different experiments and one of them, ALICE, has been specifically designed to smash together lead ions.

The goal of these collisions is to investigate what the infant Universe looked like. Colliding protons at high energies was aimed at other aspects of physics, such as finding the elusive Higgs boson particle and signs of new physical laws, such as a framework called supersymmetry.

Cern's spokesman James Gillies told BBC News that besides ALICE, the ATLAS and Compact Muon Solenoid (CMS) experiments will also be temporarily colliding ions.

 

 

 


Big Bang

He said the tests could provide an insight into the conditions of the Universe some 13.7 billion years ago, just after the Big Bang.

They will look at the Universe fractions of a second after a tiny but very dense ball of energy exploded to create the cosmos as we know it today.

At the temperatures generated, even protons and neutrons will melt, resulting in a hot dense soup of quarks and gluons”
End Quote David Evans University of Birmingham, UK

Scientists believe that it was back then that a special state of matter existed, different from the matter the Universe is formed of now.

"Matter exists in various states: you can take a material like water and if you deep freeze it, it'll be solid, and if you put it on a table, it'll turn into a liquid, and if you put it into a kettle, it'll turn into a gas," said Dr Gillies.

"It's all the same stuff, but those are different states of matter. And if you take materials into laboratories, you can pull the electrons off the atoms and you have another state of matter which is called plasma."

But at the very beginning of the Universe, there might have been yet another state of matter.

 

Physicists have dubbed this "stuff" the quark-gluon plasma.

"And this is the state of matter you have if you're able to effectively melt the nuclear matter that makes up atoms today, releasing the things that are inside, which are quarks and gluons," Dr Gillies explained.

 

 


Quark and gluon soup

If the researchers at the LHC are able to recreate that state of matter and study it, they could get important clues about how it,

"evolved into the kind of matter that can make up you and me".

One of the scientists who will be taking a part in the experiment is David Evans from the University of Birmingham, UK.

 

 

Dr Evans is one of the scientists who will take part in the new experiment
 

"Although the tiny fireballs will only exist for a fleeting moment (less than a trillionth of a trillionth of a second) the temperatures will reach over ten trillion degrees, a million times hotter than the centre of the Sun," said Dr Evans.

"At the temperatures generated, even protons and neutrons, which make up the nuclei of the atoms, will melt, resulting in a hot, dense soup of quarks and gluons."

The researcher said that the temperatures and densities that the collider will aim to create will be the highest ever produced in an experiment.
 

 

 

 

 

 

 

 

 


Large Hadron Collider (LHC) Generates A...

'Mini-Big Bang'
by Katia Moskvitch

Science reporter, BBC News
8 November 2010

from BBC Website

 

 

 

 

 

Dr David Evans:

"From conception to design and building this, it's taken about 20 years."

The Large Hadron Collider has successfully created a "mini-Big Bang" by smashing together lead ions instead of protons.

The scientists working at the enormous machine achieved the unique conditions on 7 November. The experiment created temperatures a million times hotter than at the centre of the Sun.

The LHC is housed in a 27km-long circular tunnel under the French-Swiss border near Geneva.

Up until now, the world's highest-energy particle accelerator - which is run by the European Organization for Nuclear Research (CERN) - has been colliding protons, in a bid to uncover mysteries of the Universe's formation. Proton collisions could help spot the elusive Higgs boson particle and signs of new physical laws, such as a framework called super-symmetry.

But for the next four weeks, scientists at the LHC will concentrate on analyzing the data obtained from the lead ion collisions. This way, they hope to learn more about the plasma the Universe was made of a millionth of a second after the Big Bang, 13.7 billion years ago.

One of the accelerator's experiments, ALICE, has been specifically designed to study the smashing together of lead ions, but the ATLAS and Compact Muon Solenoid (CMS) experiments have also switched to the new mode.
 

 

 


'Strong force'

David Evans from the University of Birmingham, UK, is one of the researchers working at ALICE.

He said that the collisions obtained were able to generate the highest temperatures and densities ever produced in an experiment.

"We are thrilled with the achievement," said Dr Evans.

 

One of the lead ion collisions at the LHC

 

"This process took place in a safe, controlled environment, generating incredibly hot and dense sub-atomic fireballs with temperatures of over ten trillion degrees, a million times hotter than the centre of the Sun.

"At these temperatures even protons and neutrons, which make up the nuclei of atoms, melt resulting in a hot dense soup of quarks and gluons known as a quark-gluon plasma."

Quarks and gluons are sub-atomic particles - some of the building blocks of matter. In the state known as quark-gluon plasma, they are freed of their attraction to one another.

He explained that by studying the plasma, physicists hoped to learn more about the so-called strong force - the force that binds the nuclei of atoms together and that is responsible for 98% of their mass.

 

After the LHC finishes colliding lead ions, it will go back to smashing together protons once again.

 

 

The ALICE experiment has been designed specifically for lead ion collisions