LHC beautiful diagrams of Quark 'atoms'

In the 6 September 2010: Beautiful atoms entry of the LHCb experiment web site, they have some wonderful diagrams showing how they found 'atoms' of Beauty and anti-Beauty quarks. They show how the experimental results can be mapped to the transitions where the 2 quarks drop from higher to lower energy orbitals, just like as in an Hydrogen atom.

In other news: the actual number of protons in the LHC beam is now about a millions times more than when they started this year!

LHC experiments described

I thought initially that there were 8 main experiments at the Large Hardron Collider (LHC), there are in fact 6.

Note that While they are looking at the same types of collisions, they are constructed in different ways to look at different aspects.

You can see that a large number of scientists are involved from all around the world.

It is important to have short names to refer to the experiments rather than a long but more meaningful phrase. However, you can see some groups were struggling to come up with good short names!

The following are brief excerpts about each of the experiments, click on the links for more details.


ALICE (A Large Ion Collider Experiment)
For the ALICE experiment, the LHC will collide lead ions to recreate the conditions just after the Big Bang under laboratory conditions. The data obtained will allow physicists to study a state of matter known as quark‑gluon plasma, which is believed to have existed soon after the Big Bang.
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A collaboration of more than 1000 scientists from 94 institutes in 28 countries works on the ALICE experiment (March 2006).


ATLAS
ATLAS is one of two general-purpose detectors at the LHC. It will investigate a wide range of physics, including the search for the Higgs boson, extra dimensions, and particles that could make up dark matter. ATLAS will record sets of measurements on the particles created in collisions - their paths, energies, and their identities.
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More than 2900 scientists from 172 institutes in 37 countries work on the ATLAS experiment (December 2009).


CMS (Compact Muon Solenoid)
The CMS experiment uses a general-purpose detector to investigate a wide range of physics, including the search for the Higgs boson, extra dimensions, and particles that could make up dark matter. Although it has the same scientific goals as the ATLAS experiment, it uses different technical solutions and design of its detector magnet system to achieve these.
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More than 2000 scientists collaborate in CMS, coming from 155 institutes in 37 countries (October 2006).


LHCb (Large Hadron Collider beauty)
The LHCb experiment will help us to understand why we live in a Universe that appears to be composed almost entirely of matter, but no antimatter.

It specialises in investigating the slight differences between matter and antimatter by studying a type of particle called the 'beauty quark', or 'b quark'.
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The LHCb collaboration has 650 scientists from 48 institutes in 13 countries (April 2006).


TOTEM (TOTal Elastic and diffractive cross section Measurement)
The TOTEM experiment studies forward particles to focus on physics that is not accessible to the general-purpose experiments. Among a range of studies, it will measure, in effect, the size of the proton and also monitor accurately the LHC's luminosity.
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The TOTEM experiment involves 50 scientists from 10 institutes in 8 countries (2006).


LHCf (Large Hadron Collider forward)
The LHCf experiment uses forward particles created inside the LHC as a source to simulate cosmic rays in laboratory conditions.

Cosmic rays are naturally occurring charged particles from outer space that constantly bombard the Earth's atmosphere. They collide with nuclei in the upper atmosphere, leading to a cascade of particles that reaches ground level.
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The LHCf experiment involves 22 scientists from 10 institutes in 4 countries (September 2006).

previous post: LHC discovers black rings

My previous post: LHC discovers black rings, was an April Fool's joke, just in case someone was fooled, but it did link to genuine sites. However, to someone non technical, it does give a good flavour of how particle physics is actually done, though real nuclear physicists will note inaccuracies and gross over simplifications.

I discovered after I initially wrote the previous post, that there were actual Black Rings predicted, but the chances of the LHC creating one is much lower than the LHC actually discovering the Higgs boson in a definitive way within the next week - at best physicists could hope for are a few events suggestive of the Higgs boson.

The LHC is now starting its long 3.5 TeV run to look for the new physics, but I would be surprised if there were papers published in the next 3 months revealing any new particles based on this energy level. However, I would love to be wrong in this case!

LHC discovers black rings

Now that the Large Hadron Collider (LHC) has increased its energy level to 3.5TeV (3.5 Tera electron Volts = 3,500 Giga electron Volts = 3,500,000 Mega electron Volts) new physics is starting to emerge.

Normally there is agreement not to release findings too early, as this is very much a team sport, and papers are published with hundreds if not thousands of physicists names attached. In fact the first paper published last year from an LHC collaboration had 20 pages just listing the authors.

However, a recent joiner with their PhD still fresh, emailed a friend with some exciting news about the discovery of Black Rings – obviously not realizing that such would soon become public.

Well apparently they had recorded 97 double collisions in the CMS experiment, where the second collision happened within a few picoseconds of the first. This meant that particles ejected from the second interacted with products of the previous collision. Initial analysis was very puzzling, as some anomalous tracks were discovered. Fortunately a brilliant theoretical Nuclear Physicist from Estonia, Prof. Selrahc Nivag, found a possible explanation, a Black Ring.

A Black Ring is a theoretical possibility when an intense gravitational field interacts with strange quarks. Now quarks are normally bound up with others and not seen by themselves. The first collision generated hadrons containing strange quarks, the second collision generated transient super dense collection of protons and neutrons (a hyper nucleus) with a high quantum spin number, and their interaction created a transient Black Ring which lasted less than a microsecond.

About 34 of the 97 double collisions gave anomalous results tentatively identified with Black Rings. Theoretical predictions suggest that for collisions of this type, after allowing for variations in the precise details of the actual double collisions, would generate 31 such events – not bad correlation, considering the accuracy of the measurements, and within the expected margin of experimental error.

A Black Ring is predicted to decay in a flash of gamma radiation with several particles flying out in the same plane as the ring. Additionally, in 3 of the Black Ring events, later particles were seen going through the centre of the Black Ring – identified by particle tracks ending abruptly where the Black Ring was, and having continuation tracks indicating they had been converted to their anti-matter counter parts (the surrounding magnetic field caused the tracks to curve in opposite directions, due to the abrupt change in the sign of the charged particles).

This interpretation is still highly speculative, as the significance is only at the level of 2 standard deviations, and physicists prefer to get enough data for it to be valid at at least 7 standard deviations.

So no Black Holes, just a few Black Rings – maybe.

The Large Hadron Collider will restart soon at 7 TeV

The Large Hadron Collider, otherwise known as the LHC, is designed to hurl protons and nuclei of atoms together a phenomenally high speeds extremely close to the speed of light.

The LHC has 2 beams going in opposite directions around an oval of about 27 kilometres, at specified pints, where experiments like ATLAS and CMS are located, they cross and collisions may occur.

These collisions are at an energy high enough that particles are created from the interaction of the colliding protons and neutrons. Most of the particles detected from these collisions are known, but physicists are still interested in how they behave at the energies achieved in the LHC, but the most sought after prize is the Higgs Boson - along with possibility of finding other particles predicted, but not yet observed.

Theoretical nuclear physicists can not account for why the sub atomic particles, that we have already detected so far, have mass. So Peter Higgs, along with others, postulated a totally new type of particle, now called the Higgs Boson, that appears to neatly resolve the problem.

Some other physicists, think that the Higgs Boson does not exist, and there must be some other mechanism to account for mass. However, most physicists feel that searching for the Higgs is worthwhile, as it is important to find evidence of it either definitely existing or not existing, as the case may be. The existence of the Higgs would confirm our understanding of the so called standard model of nuclear particles and allow our understanding of it to be extended to higher energies, or force physicists to reconsider the standard model in a very fundamental way.

Also of considerable interest: would be new types of particles not predicted, and new ways of matter behaving at the super high temperatures found in the collisions of nuclear particles at the LHC.

The LHC had been designed to run at 10 TeV (10,000,000,000,000 electron volts, as distinct from the maximum energy possible in the average New Zealand home of 240 volts), but due to technical problems they will run at 7 TeV. The LHC will be run at this energy for 18 to 24 months to get a decent amount of physics done and to get more experience of operating the system, plus it gives more time to prepare what is required to operate at the design energy of 10 TeV.

Note that the LHC is run at about 270 degrees Celsius below the freezing point of water, or less than 2 degrees above absolute zero. So another reason for the long period at just one energy level of 7 TeV, is that while there are improvements they can make to increase the energy in stages to 10 TeV, is that simply warming the LHC up to room temperature and cooling it down again takes at least 2 months, in addition to the time required to make the actual engineering modifications and subsequent testing.

It is expected that the LHC will restart operations in the few days about the level it finished last year of about 1 TeV and ramp up over a few week to 7 TeV. They want to avoid any mishaps that might put the LHC out of commission, like what happened shortly after they started up the first time when they had an explosion that forced a delay of a year while they fixed the problem.

Physicists from all around the world are hard at work preparing to do some exciting new physics at the LHC, including some people from New Zealand.

Scientists are Careful and Responsible

Tom Whyntie, a physicist at the LHC, commented on the possible detection of Dark Matter by a rival experiment. Note that he is respectful of them, and also points out the importance that independent experiments have in verifying discoveries.

Dark matter appears to be responsible for over 80% of the mass of the Universe, but we have not yet discovered any, despite much evidence suggesting it exists. So there would be huge prestige for any scientist who discovered it.

Most people never realize how careful and responsible scientists are, as despite intense rivalries they fully appreciate the need for cooperation.

The quoted article gives a good insight into what makes good science practice.
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In a very real, technical sense, the answer is no (and, of course, I'm not just saying that because I work on the LHC!). The observation of "only" two events does not a discovery make, and CDMS very carefully and responsibly state this in their announcements -- not because of modesty, but because they are good scientists. Statistics, to put it mildly, are tricky at the best of times and pretty much a nightmare when it comes to discoveries. They are very rightly exercising caution. It's how science works.
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LHC restarts!

Probably the most exciting thing happening now in Science, is the restart of the Large Hadron Collider (commonly referred to as the LHC)! A massive explosion required about a year to fix, and to re-engineer to try and prevent such a problem happening again - those events, and the current status are documented.

The LHC is an enormous apparatus that is mostly a ring 27 kilometres in circumference half in France and half in Switzerland, designed to smash together the nuclei of atoms to produce as yet undetected elementary particles.

The ring has 8 major experimental stations such as the CMS and ATLAS experiments, that are 'sort of' general purpose detectors with different characteristics, each weighing over ten thousand tonnes.

The Director of the LHC, Steve Myers, paid tribute to the huge amount of dedicated team work involved.

They are starting at relatively low energies, as they need to carefully bring the machine up to its design level. So at the moment they can only see the types of particle they already know about.

At full strength they hope to detect the particle that a lot of physicists think is responsible for why other particles, such as the proton and electron have mass. This particle is called the Higgs Boson, named after Peter Higgs. If they don't find it, and can demonstrate it does not exist at the energies that the LHC can reach, then this is also interesting as it will lead to new physics.

Apart from the Higgs Boson, there is a potential doubling of the number of particles needed to explain the world according to the Super Symmetric Theory (affectionately known as SUSY), these are expected to discovered by the LHC. Plus there is the 'expected unexpected' discoveries.

Some good URL's to look at are:

Pretty pictures of the LHC
Physicists blogging
Official LHC website
Unofficial LHC webisite
LHC on Twitter
Collision events as they happen at the CMS experiment