Asif Mahmood Abbas
Mayesha Tafannum
Awsaf Mahmood Lisan
Hello! The coolest readers of YOUTHWAVE. Welcome you again to the world of Future Science. In this edition we will take you to area between Switzerland and France, where the largest scientific experiment ever undertaken is going on. We hope you will definitely like this article.
At the Conseil Européen pour la Recherche Nucléaire (CERN), or European Council for Nuclear Research, they have been planning and constructing the biggest machine in the history of planet Earth. This is the Large Hadron Collider – a gigantic synchrotron over 8 km in diameter, built 100 metres underground on the border between Switzerland and France. On 10 September 2008, it was switched on (after a couple of years of delay), at a cost of just under four Billion Euros, with staff from 111 nations involved in its building and operation. It is the largest experiment ever undertaken. Running at 1.9K the LHC will be the coldest place in the solar system when running (excluding colder man-made experiments).
Four Smashing Experiments
The machine is designed to collide protons into each other at energies of 14TeV, travelling at 99.9999991% of the speed of light. These conditions emulate those occurring in the Universe 1 billionth of a second after the Big Bang. LHC scientists are hoping that this will then produce particles and interactions not seen since the Big Bang.
At such high energies, the beams of protons counter-rotating around the 27km ring will cross each other’s paths 30 million collisions per second. There are four critical experiments in the LHC, each named by an acronym: CMS, LHCb, ATLAS and ALICE. Each of the experiments has an incredibly complex detector built in a cavern around the accelerator and one of the beam-crossing points is at the centre of each detector. Each experiment is aimed at detecting particular products from the collision; each is searching for specific undiscovered but theoretical particles.
The detectors include strong magnetic fields and will track the movements of particles through the space that the detector occupies. As mass-energy and momentum are always conserved in particle interactions, along with charge, the records of particle tracks can be interpreted to identify the particles in the detector and any reactions that they undergo.
CMS – the Compact Muon Solenoid
If the Large Hadron Collider achieves the exiting discoveries it has been designed for, they well may come from this detector. There are several hypotheses in different areas of theoretical physics which may gain confirmation evidence from the LHC. Some of these sound a little bizarre. For example, it is hoped that the CMS will observe mini black holes, dark matter, super symmetric particles, gravitons and the Higgs boson.
The CMS is set up with various detecting chambers for different types of particle and has 100 million individual detectors organized in a 3D barrel containing as much as iron as the Eiffel Tower. By monitoring the tracks of particles their charges and masses can be determined. The energies and momenta can also be measured, and all this information analysed together can identify all the particles and reactions in each collision.
LHCb – Large Hadron Collider beauty experiment
This detector will be watching out for the decays of both the bottom quark (sometimes called beauty) and the charm quark by looking for mesons containing these.
This is particularly aimed t working out why our Universe contains mostly matter and very little antimatter, when theoretically the two should appear in equal amounts.
ALICE – A Large Ion Collider Experiment
Although ALICE will initially observe the proton-proton collisions that the LHC will start with, this detector is particularly intended to study the collisions of heavy ions, such as lead, accelerated to almost the speed of light.
It is hoped that these collisions will create a quark-gluon plasma which has been predicted by quantum mechanics theory.
ATLAS
The ATLAS detector is 45m long and 25m high. Among the possible discoveries are the origin of mass, extra dimensions of space, microscopic black holes, and evidence for dark matter particles in the universe.
Originally, ATLAS was an acronym for A Toroidal Lhc ApparatuS, but this has largely been dropped and it is simply the name of the experiment.
What must a detector be capable of doing?
In developing the Large Hadron Collidor experiment, the scientists had to work out what they needed the detectors to do. The following nine points are listed on the ATLAS website as their intentions as to the abilities of the detector:
1) Measure the directions, momenta, and signs of charged particles.
2) Measure the energy carried by electrons and photons in each direction from the collision.
3) Measure the energy carried by hadrons (protons, pions, neutrons, etc) in each direction.
4) Identify which charged particles from the collision, if any are electrons.
5) Identify which charged particles from the collision are muons.
6) Identify whether some of the charged particles originate at points a few millimeters from the collision point itself (signaling a particle’s decay a few millimeters from the collision point).
7) Infer (through momentum conservation) the presence of undetectable neutral particles such as neutrinos).
8) Have the capability of processing the above information fast enough to permit flagging about 10-100 potentially interesting events per second out of the billion collisions per second that occur, and recording the measured information.
9) The detector must also be capable of long and reliable operation in a very hostile radiation environment.
Data analysis
It has been estimated that the amount of data resulting from the LHC experiments will be approximately 10% of that produced through all human activities across the world. To analyse the raw data from the incredibly complex detectors, a system of computer analysis called the Grid will be used. This enables hundreds of computers across the world to be linked together via the internet in order that their combined computing power can be used to study the experiment results and search out any which indicate the discoveries it is hoped the LHC will produce. Of every 10 billion collision results, we expect only about 10-100 will be ‘interesting’ reactions. The ones that show things we already know need to be quickly filtered out of the data so that computing power is not wasted.
Large Hadron Collider could “open door to new physics by yearend”
The world’s largest particle accelerator could provide key insights into the makeup of matter and change our view of physics as early as at the end of 2010, the director of the European Organization for Nuclear Research (CERN) said.
The LHC was restarted at the end of February and repeated its record collision energy output of 2.36 tera-electron volts (TeV) on March 8. Scientists plan to force the particles to collide at 7 TeV by the end of March.
The collider will run at 7 TeV through next year, before being shut down in 2012 to upgrade to full design energy of 14 TeV. It will then restart in 2013.
Speaking at a March 8 news conference, Rolf-Dieter Heuer said the LHC could start generating its first scientific breakthroughs into elusive dark matter as early as later this year, even while operating at half-capacity.
“We will open a door for new physics by the end of this year,” Heuer told reporters. “It took several decades for us to understand the visible universe. This is all nicely explained by the standard model, but the big problem is that this is only 5 percent of the universe.”
“If we can detect and understand dark matter, our knowledge will expand to encompass 30 percent of the universe, a huge step forward,” he added.
The $5.6 billion international LHC project has involved more than 2,000 physicists from hundreds of universities and laboratories in 34 countries since 1984. Over 700 Russian physicists from 12 research institutes have taken part.
The collider, located 100 meters under the French-Swiss border with a circumference of 27 km, enables scientists to shoot subatomic particles round an accelerator ring at almost the speed of light, channeled by powerful fields produced by superconducting magnets.
In order to fire beams of protons round the vast underground circular device, the entire ring must be cooled by liquid helium to minus 271 degrees C, just two degrees above absolute zero.
By colliding particles in front of immensely powerful detectors, scientists hope to detect the Higgs boson, nicknamed the “God particle,” which was hypothesized in the 1960s to explain how particles acquire mass. Discovering the particle could explain how matter appeared in the split-second after the Big Bang.
Thanks for being with us. Hope to see you again, in another edition of Monthly YOUTHWAVE.
Adapted, Edited and Compiled from:
Wikipedia, Future Science, Modern Physics, Edexcel A2 Physics, The particle Anatomy, The miracles of Physics.
Special thanks to:
Ranjan Kumar Bishwas, UniWorld Education. Mohsin Ahmad, Taha Yeasin Ranan and Asif Iqbal Choudhury.