Sunday, July 20, 2008

Will t Large Hadron Collider Destroy the Earth?

Skeptoid #109
July 15, 2008
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As you may have heard by now, some people have voiced concerns that particle collisions from the LHC will create tiny black holes. Black holes have such intense gravity that they consume everything around them, even light. And so,

within a fraction of a second, this tiny black hole will consume the collider itself, France, Switzerland, and then the entire Earth, presumably followed shortly thereafter by our whole solar system.
Clearly not a fear to be taken lightly.

The best known opposition to the Large Hadron Collider comes in the form of a much publicized lawsuit, filed in Hawaii by two individuals, science writer Luis Sancho and retired nuclear safety officer Walter L. Wagner, against the US Department of Energy, Fermilab, CERN, the National Science Foundation and Does 1-100.

The lawsuit presents affidavits from the plaintiffs and five other individuals, stating their opinion that dangerous black holes could be formed and seeking to block operation of the collider until these fears can be adequately studied.
It seems a reasonable precaution, given how incredibly gigantic and powerful the LHC is, and how Biblical the scale of the destruction it might wreak.

More...

Aims of LHC - 2


The Large Hadron Collider

Our understanding of the Universe is about to change...

The Large Hadron Collider (LHC) is a gigantic scientific instrument near Geneva, where it spans the border between Switzerland and France about 100 m underground.

It is a particle accelerator used by physicists to study the smallest known particles – the fundamental building blocks of all things. It will revolutionise our understanding, from the miniscule world deep within atoms to the vastness of the Universe.

Two beams of subatomic particles called 'hadrons' – either protons or lead ions – will travel in opposite directions inside the circular accelerator, gaining energy with every lap. Physicists will use the LHC to recreate the conditions just after the Big Bang, by colliding the two beams head-on at very high energy. Teams of physicists from around the world will analyse the particles created in the collisions using special detectors in a number of experiments dedicated to the LHC.

There are many theories as to what will result from these collisions, but what's for sure is that a brave new world of physics will emerge from the new accelerator, as knowledge in particle physics goes on to describe the workings of the Universe. For decades, the Standard Model of particle physics has served physicists well as a means of understanding the fundamental laws of Nature, but it does not tell the whole story.

Only experimental data using the higher energies reached by the LHC can push knowledge forward, challenging those who seek confirmation of established knowledge, and those who dare to dream beyond the paradigm.

Reference: Image

Aims of LHC - 1

When in operation, about seven thousand scientists from eighty countries will have access to the LHC, the largest national contingent of seven hundred being from the United States. Physicists hope to use the collider to test various grand unified theories and enhance their ability to answer the following questions:

Reference: http://en.wikipedia.org/wiki/Large_Hadron_Collider

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Standard Model of Elementary Particles

Sub-atomic table
The Standard Model (reference) is a theory devised to explain how sub-atomic particles interact with each other
There are 16 particles that make up this model (12 matter particles and 4 force carrier particles). But they would have no mass if considered alone
The Higgs boson explains why these particles have mass. Particles acquire their mass through interactions with an all-pervading field, called the Higgs field, which is carried by the Higgs boson.


Reference

Saturday, July 19, 2008

Cern lab goes 'colder than space'

By Paul Rincon
Science reporter, BBC News

LHC tunnel (M. Brice/Cern)
Superconducting magnets are cooled down using liquid helium

A vast physics experiment built in a tunnel below the French-Swiss border is fast becoming one of the coolest places in the Universe.

The Large Hadron Collider is entering the final stages of being lowered to a temperature of 1.9 Kelvin (-271C; -456F) - colder than deep space.

The LHC has thousands of magnets which will be maintained in this frigid condition using liquid helium.

The magnets are arranged in a ring that runs for 27km through the giant tunnel.

Once the LHC is operational, two particle beams - usually consisting of protons accelerated to high energies - will be fired down pipes running through the magnets.

These beams will then travel in opposite directions around the main ring at close to the speed of light.

At allotted points along the tunnel, the beams will cross paths, smashing into one another with cataclysmic force. Scientists hope to see new particles in the debris of these collisions, revealing fundamental new insights into the nature of the cosmos and how it came into being.

The most powerful physics experiment ever built, the LHC will re-create the conditions just after the Big Bang.

Currently, six out of the LHC's eight sectors are between 4.5 and 1.9 Kelvin, though all sectors of the machine have been down to 1.9 Kelvin at some stage over the last few months.

By comparison, the temperature in remote regions of outer space is about 2.7 Kelvin (-270C; -454F).

CMS detector at end of 2007 (M. Brice/Cern)
The CMS detector will search for the Higgs boson - the so-called "God particle"

Roberto Saban, the LHC's head of hardware commissioning, said that in order to obtain high magnetic fields without consuming too much power, the magnets were required to be "superconducting".

This is the property, exhibited by some materials at very low temperatures, to channel electrical current with zero resistance and very little power loss.

Helium exhibits spectacular properties at 2.2 Kelvin - becoming "superfluid". This allows it to conduct heat very rapidly, making it an extremely efficient refrigerant.

No particle physics facility on this scale has ever operated at such low temperatures. But, so far, the hardware was performing as predicted, Roberto Saban explained.

"We have a very systematic process for the commissioning of this machine, based on very carefully designed procedures prepared with experience we have gathered on prototypes."

He added: "Our motto is: no short cuts? exchanging a single component which today is cold, is like bringing it back from the Moon. It takes about three to four weeks to warm it up. Then it takes one or two weeks to exchange. Then it needs three to six weeks to cool down again.

"So, you see, it is three months if we make a mistake."

Two sectors of the LHC are currently not cold enough for testing to proceed. Electronics that control the cryogenic systems in these sectors are being moved to an area where they will be better shielded against particles that shoot out of the machine during collisions.

Closing the circle

One sector of the ring is being run as if the LHC was operational and carrying a beam. This is so that crews can de-bug software and hardware and gain experience of running operating cycles.

The LHC's magnets must also undergo electrical testing. Each sector of the machine contains about 200 electrical circuits. Each circuit may consist of as many as 154 magnets or as few as one.

They are being tested for their ability to handle very high currents - up to 12,000 Amps .

"We power each circuit, making sure it goes to its design current. But above all, we are verifying that all the protection systems around it - which are there to detect an eventual quench - are operating as expected," said Roberto Saban.

A quench occurs when some part of the magnet starts to heat up, becoming resistant to electrical current. Engineers have built in a recovery system to detect these quenches before they affect the magnetic field bending particles around the ring and shut off the circulating beams.

The machine's cool-down should take another two weeks to complete, provided no serious problems are found. Electrical testing of the magnets may take another couple of weeks.

Before the LHC is "switched on" for the first time, the proton beams have to be boosted to high energies in a chain of particle accelerators called the injectors.

Once the machine is cold, operators will inject beams into the main ring, threading them through each independent sector of the LHC until they close the circle.

A timing, or synchronisation, system is used to ensure each of these sectors behaves as if they were a single machine.

When the LHC is switched on it will operate at an energy of five trillion electron-volts. It will then be shut down for the winter, so that the magnets can be "trained" to handle a beam run at seven trillion electron-volts.

Paul.Rincon-INTERNET@bbc.co.uk

About LHC - 2

Brief Description of the LHC.

Energising the quest for 'big theory'
By Paul Rincon

BBC News science reporter, Geneva

Cern's Atlas detector will search for the elusive "God particle" (Image: Cern/Maximilien Brice)

"We are at a point where experiments must guide us, we cannot make progress without them," explains Jim Virdee, a particle physicist at Imperial College London.

"We must wait for the data to speak."

Over a coffee in the lobby of building 40 at Cern, the sprawling experimental facility situated on the Swiss-French border, Professor Virdee says physics has reached a critical juncture.

In the 1970s, the theory known as the Standard Model was considered a triumph of theoretical physics, incorporating all that was then known about the interactions of sub-atomic particles.

Today it is regarded as incomplete, a mere stepping stone to something else.

The Standard Model cannot explain the best known of the so-called four fundamental forces: gravity; and it describes only ordinary matter, which makes up but a small part of the total Universe.

The Large Hadron Collider (LHC) at Cern (The European Centre for Nuclear Research) is costing some 3bn Swiss francs (1.9bn euros; £1.3bn), which is paid for by contributions from Cern's member countries (including the UK) with support from international partners such as the US, Japan, China and India.

It should reinvigorate physics' biggest endeavour: a grand theory to describe all physical phenomena in nature.

The Large Hadron Collider takes shape

About 100m below us, in a tunnel that runs in a ring for 27km (17 miles), the LHC is being assembled
from its constituent parts like a vast, impossibly complex Meccano set.

When it is switched on for a pilot run in summer 2007,

this huge physics experiment will collide two beams of particles head-on at super-fast speeds, recreating the conditions in the Universe moments after the Big Bang.

The beam collisions should create showers of new particles, revealing new physics beyond the Standard Model. In order for that to happen, the LHC needs to reach much higher energies than previous colliders.

Sealed vacuum

The particle beams, composed of either protons or lead ions, will be created in Cern's existing chain of particle accelerators and then injected into the LHC. Here they will receive an additional electrical impulse to boost them up to their final energy; the equivalent of seven trillion volts.

Some 1,232 "dipole magnets" will carry these high energy beams through their interior and bend them around the LHC.

Each one undergoes a rigorous quality test before it can be lowered into the tunnel. At the Cern site known as SM18, Dr Mike Lamont, from Cern's beam operations group, shows us round the hangar-like facility where the magnets are put through their paces, 12 at a time.

The tests are run at 1.9 Kelvin (-271C), the eventual operating temperature of the LHC. This is just a shade above "absolute zero" and colder than the vacuum of outer space. The magnets are cooled to this ultra-low temperature by bathing them in liquid helium.

The magnets undergo thorough testing before they are lowered into the tunnel

When helium is cooled to 2.17 Kelvin, it exhibits remarkable properties. In this "superfluid" state, it flows with almost zero viscosity and an unusually high thermal conductivity. This makes it ideal for cooling and stabilising a large superconducting system like the one at the LHC.

In 2007, Mike Lamont will be one of the machine co-ordinators "driving" the LHC: "It's a huge challenge," he says. "The magnets are one thing, but then you've got 27km of instrumentation and controls. Everything's got to be synchronised incredibly well."

At four points around the LHC ring, the two beams cross each other, causing some of the particles to collide head-on. Near each of the crossing points will sit a detector, an experiment the size of a mansion, to capture and measure new particles produced in the collisions.

Simulation of Higgs decay, Cern
A simulation shows what a Higgs signature might look like
The LHC's four detectors are named LHCb, Alice, Atlas and the Compact Muon Solenoid (CMS). Each is worked on by a dedicated team of physicists.

While LHCb and Alice are designed to investigate specific physical phenomena, Atlas and CMS are designated "general purpose" detectors.

They will both aim to identify the elusive Higgs boson (known as the "God particle" because of its importance to the Standard Model), look for so-called supersymmetric particles and seek out the existence of extra dimensions.

As such,

the scientists working on Atlas will to some extent be competing with those on CMS. Both teams aim to be first to find the Higgs, leaving the other to "verify" their discovery
(a scientific euphemism, one suspects, for "eat humble pie").

Mass giver

The Higgs boson explains why all other particles have mass. According to the theory, particles acquire their mass through interactions with an all-pervading field, called the Higgs field, which is carried by the Higgs boson.

At Point One in Switzerland, we don hard hats, squeeze into a lift with the construction workers and descend into the enormous cavern that will house Atlas, the bigger of the two general purpose detectors.

The modules that make up this giant experiment have been built separately in laboratories around the world and transported to Cern for assembly.

"The same happens with big aircraft such as the Airbus A380," observes Dr Alan Barr, a physicist at University College London and Atlas team member. "They make all the bits separately, bring them together and it all fits.

"The thing is, we only ever build one," comments Cern scientist and Atlas team member Dr Pippa Wells. "We don't make one Atlas, then another, and find out we know what we're doing by the fifth."

"We've got one shot, it's got to work first time," says Alan Barr.

Testing time

Over the border at Cessy in France, the CMS team will soon begin testing individual "slices" of its experiment to see whether each can detect cosmic rays from space.

Much of the assembly of the CMS is taking place above ground. Large elements will then be lowered by crane into the underground cavern built to house it. This process will take about six months.

View from the ground of a CMS barrel station, BBC/Paul Rincon
Individual slices of the CMS will be tested above ground
A wrangle over the supply of crystals lining the detector's electromagnetic calorimeter (which measures the energies of particles produced in collisions) has now been resolved. But part of this component won't be ready for installation in CMS by the LHC's pilot run in 2007.

However, says team member Jim Virdee, the calorimeter will be complete and installed in the CMS by April 2008, ready for the start of the LHC's main science run. The delay won't put the CMS at a disadvantage in the race to find the Higgs, he adds, since

over a year's worth of data will be needed to announce a discovery.

Cern's chief theorist Professor John Ellis even thinks

finding the Higgs could shed light on another great mystery in physics: dark energy.

Dark discovery

In 1998, two teams studying supernovae showed that this dark energy is accelerating the expansion of the Universe. Subsequent work revealed that dark energy may make up about 70% of the Universe, but the best theories could not explain it.

According to John Ellis, however,

the Higgs field is the perfect candidate for the source of dark energy.

"The Higgs mechanism fills all of space with a field. Unlike the gravitational field, which is strong around the Sun and the centre of the galaxy, the Higgs field would have essentially the same value everywhere,"
he explains.

"It would give you dark energy, in the sense that dark energy is energy density in empty space a long way away from any matter."

There's just a small problem with the idea, says John Ellis: it gives 120 orders of magnitude too much dark energy.

"If we find the Higgs, it would corroborate this whole theory that there's this Higgs field sitting throughout the Universe providing dark energy. Then we can get on to the next question which is why it has the value it does."

Such a breakthrough would energise debate on a "unified theory" to describe all natural phenomena. Discoveries such as supersymmetry may also bridge gaps between experimental evidence and string theory, one attempt at building a grand scheme.

The LHC might even reveal something completely unexpected about the workings of our Universe. And that, say physicists, might be even more satisfying.

Sub-atomic table
The Standard Model is a theory devised to explain how sub-atomic particles interact with each other
There are 16 particles that make up this model (12 matter particles and 4 force carrier particles). But they would have no mass if considered alone
The Higgs boson explains why these particles have mass. Particles acquire their mass through interactions with an all-pervading field, called the Higgs field, which is carried by the Higgs boson.


About LHC - 1

Underground search for 'God particle'
By Paul Rincon
BBC News science reporter in Geneva, Switzerland

A circular tunnel runs for 27km under the French-Swiss border

At the foot of the Jura Mountains, where Switzerland meets France, is a laboratory so vast it boggles the mind.

But take a drive past the open fields, traditional chalets and petite new apartment blocks and you will look for it in vain.

To find this enormous complex, you have to travel beneath the surface.

One hundred metres below Geneva's western suburbs is a dimly lit tunnel that runs in a circle for 27km (17 miles).

Nature is much smarter than us. It might come up with a real surprise and that would be much more interesting - much more satisfying
Professor Jim Virdee, Imperial College London
The tunnel belongs to Cern, the European Centre for Nuclear Research. Though currently empty, over the next two years an enormous experiment will be installed here.

The Large Hadron Collider (LHC) is a powerful and impossibly complicated machine that will smash particles together at super-fast speeds in a bid to unlock the secrets of the Universe.

'New physics'

By recreating the searing-hot conditions fractions of a second after the Big Bang, scientists hope to see new physics, discover the sought-after "God particle", uncover new dimensions and even generate mini-black holes.

When completed, two parallel tubes will carry high-energy particles called protons in opposite directions around the tunnel at close to the speed of light.

The Atlas experiment will join the search for the Higgs boson at Cern

The tunnel's huge circumference provides only the slightest of bends. Nevertheless, around 5,000 superconducting magnets are needed to steer and focus the particles around the tubes.

"When the coils are energised there is one jumbo jet - 500 tonnes - per metre pushing outwards,"
says LHC project leader Lyn Evans.

Along the way, the proton beams will pass through enormous experimental instruments called detectors where they will cross.

When some of these protons collide at high energy, heavier particles can appear amongst the debris.

Great quest

When the LHC is turned on in the latter half of 2007, physicists will scour this crash wreckage for signs of the Higgs boson.

The Higgs is nicknamed the God particle because of its importance to the Standard Model, the theory devised to explain how sub-atomic particles interact with each other.

The 16 particles that make up this model (12 matter particles and 4 force carrier particles) would have no mass if considered alone. So another particle - the Higgs boson - is postulated to exist to account for this omission.

The CMS is constructed from different layers in an "onion" structure

"The Standard Model is the best thing we've come up with so far," says Jim Virdee, spokesman for the team working on the

Compact Muon Solenoid (CMS) detector.

But everyone recognises it is merely a stage on the way to something else. The Standard Model describes ordinary matter and yet astronomical observations show this makes up but a small part of the total Universe.

Needless to say, new theories are gaining ground and discoveries at the LHC could lead physicists towards a unified theory to explain how the Universe works.

"We are at a stage where the theorists do not know which direction to go in. The results from [our] experiment will determine which direction science takes," says Professor Virdee, who is based at Imperial College London, UK.

"We don't always like theorists to tell us what we should find. Nature is much smarter than us.

"It might come up with a real surprise and that would be much more interesting - much more satisfying."

Huge scale

The detectors at the LHC will count, trace and analyse the particles that emerge from the collisions between protons.

To call them experiments simply does not give an idea of their scale. The equipment weighs tens of thousands of tonnes and in some cases is as tall as a multi-storey building.

A giant cavern will house the CMS detector at Cern

This week marked the inauguration of the enormous cavern at Cessy in France that will house the CMS. A 78m-long shaft leads up to the surface, through which the CMS will be lowered by crane early next year.

Both the CMS and its rival experiment, Atlas, are based on a cylindrical "onion" structure with several layers to perform different roles.

By 2010, nearly one billion collisions will take place every second in these detectors.

"CMS needs to collect a sample of several hundred collisions out of 40 million. And we have just three microseconds to decide whether a collision produced something interesting," Professor Virdee told the BBC News website.

High energy

After attending the CMS inauguration, we travelled just across the border to Switzerland, where the Atlas cavern is located.

Measuring 53m long, 30m wide and 35m high, it is taller than Canterbury Cathedral and is currently empty but for the support structures that will hold the detector in place.

The Atlas cavern could fit a 12-storey building inside it

"You're visiting at a good time; it won't look like this again," says Atlas technical co-ordinator Mark Hatch.

High radiation levels when the LHC is running mean access to these caverns will be forbidden when the machine is in operation, creating problems for the scientists.

The energies achieved by the experiment are 70 times greater than those of the Large Electron-Positron Collider (LEP) which previously occupied the tunnels at Cern.

Only by raising the bar will scientists be able to expand our current understanding of the Universe.

Whatever the discoveries ahead for physicists working at the LHC, the experiments will, according to its chief scientific officer, Jos Engelen, "keep physicists off street corners for a long time to come".

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