What really goes on at the Large Hadron Collider?
What really goes on at the Large Hadron Collider?
What are the questions that it actually seeks to answer? I’ll begin by outlining these questions.
The Higgs mechanism: Can the Higgs boson be empirically detected? What if it doesn’t actually exist?
(A bit of trivia about the Higgs boson:
When Leon Lederman wrote The God Particle, and coined that phrase, which journalists love, and scientists hate, he originally wanted to call it the goddamn particle, but the publisher wouldn’t allow it.)
Even if a Higgs boson is not found, at the TeV-scale energies being probed here, there will be an extremely good chance of getting some insights into whatever process is responsible for things like electroweak symmetry breaking, if it’s not the Higgs mechanism.
The Hierarchy Problem: Why is gravity such a very weak force, compared to the other fundamental forces? Is the answer related to higher spatial dimensions, or to supersymmetry?
Higher dimensions: Can we empirically “see” evidence of higher spatial dimensions in the universe in high-energy particle interactions? What are those dimensions like? What are their properties?
CP-violation: How was CP-violation established in the primordial universe, to the degree that it was? What mechanism is responsible for the CP-violation, and the resultant amount of matter in the cosmos?
Dark matter: It’s quite well accepted today that there is indeed “dark matter”, and it is comprised of weakly-interacting particles that have a significant amount of mass. Exactly what are these particles? Could the lightest supersymmetric particles, such as the neutralino, if they exist, be consistent with the dark matter?
Black holes: If “micro black holes” really could be produced in LHC interactions, do they behave as predicted by Hawking, evaporating and radiating Hawking radiation?
Supersymmetry: If supersymmetric particles can be observed, what is the mechanism responsible for supersymmetry breaking, making the s-particles so massive, compared to the familiar standard model particles? Can the existence of supersymmetry explain the strength of gravity, or the composition of dark matter?
Every one of these areas is potentially going to be answered, or research is going to be considerably furthered, by work at the LHC.
An entire book (or many) could be written on each and every one of these things. For now, though, I’ll elaborate a little on just one of these areas of interest – CP-violation and its connection to cosmology.
One of the great open problems in physics at the moment is the question of why the Universe has so much matter in it, and essentially no antimatter.
If matter and antimatter (quarks and antiquarks, fundamentally) were created in equal amounts following the Big Bang, then all the matter and antimatter would annihilate, and the matter-filled Universe we see would not exist.
Something that we might expect, perhaps somewhat naively, from laws of physics is CP-symmetry – that is, that the laws of physics are ‘symmetrical’ under CP-transformation (CP- as in a combination of both Charge and Parity operators.) In other words, basically, the laws of physics are “symmetrical” between matter and antimatter, since CP-symmetry is the symmetry between matter and antimatter. We might expect particles and antiparticles should behave “symmetrically” in every way.
However, as per the above, this isn’t true. At least, it’s not always true. There exists some mechanism whereby CP-symmetry is perturbed, just a tiny bit – it was perturbed just enough in the early universe to create the universe that we see. This is CP-violation, an example of a symmetry violation in physics.
The CP operator is the product of two: C for charge conjugation, which transforms a particle into its antiparticle, and P for parity, which creates the mirror image of a physical system. The strong interaction and electromagnetic interaction seem CP-invariant, but a slight degree of CP-violation is observed in weak interactions under certain conditions.
The greater the degree of CP-violation present in the early Universe, the greater the amount of matter left in the Universe. Thus, the understanding of CP-violation plays an important role in cosmology, in explaining the amount of matter in the universe, which is a rather important quantity, from the point of view of physical cosmology.
Quoteth Wikipedia a bit because I’m getting sick of writing and can’t remember exact dates and all the names:
Until 1956, parity conservation was believed to be one of the fundamental geometric conservation laws (along with conservation of energy and conservation of momentum). However, in 1956 a careful critical review of the existing experimental data by theoretical physicists Tsung-Dao Lee and Chen Ning Yang revealed that while parity conservation had been verified in decays by the strong or electromagnetic interactions, it was untested in the weak interaction. They proposed several possible direct experimental tests. The first test based on beta decay of Cobalt-60 nuclei was carried out in 1956 by a group led by Chien-Shiung Wu, and demonstrated conclusively that weak interactions violate the P symmetry or, as the analogy goes, some reactions did not occur as often as their mirror image.
Only a weaker version of the symmetry could be preserved by physical phenomena, which was CPT-symmetry. Besides C and P, there is a third operation, time reversal (T), which corresponds to reversal of motion. Invariance under time reversal implies that whenever a motion is allowed by the laws of physics, the reversed motion is also an allowed one. The combination of CPT is thought to constitute an exact symmetry of all types of fundamental interactions. Because of the CPT-symmetry, a violation of the CP-symmetry is equivalent to a violation of the T-symmetry. CP violation implied nonconservation of T, provided that the long-held CPT theorem was valid. In this theorem, regarded as one of the basic principles of quantum field theory, charge conjugation, parity, and time reversal are applied together.
From that last paragraph, of course, we arrive at the seemingly incredible conjecture, which is absolutely true, that an antiparticle is a corresponding particle… it’s just traveling backwards in time, as was explained perhaps most famously by Richard Feynman. That is indeed how Quantum Field Theory predicts the existence of antiparticles.
The (neutral K) meson (or kaon) consists of a down quark and a strange antiquark – – and its corresponding antiparticle is of course made up of a strange and an anti-down, .
Similarly, the is , and the is . (B mesons, by definition, contain a b quark/antiquark, which is why they’re named thus, and kaons contain a strange combined with a non-strange quark.)
These mesons can ‘oscillate’ back and forth – with a particle spontaneously turning into the antiparticle, and vice versa, as shown in this Feynman diagram.
But the transition between particle and antiparticle and between antiparticle and particle don’t occur at quite the same rate – because of the CP-violating term!
Whilst CP-violation was first experimentally discovered, it was discovered in neutral Kaon interactions – but today, most experimental studies of CP-violation deal with the B-mesons.
Two of today’s best known particle physics experiments investigating CP-violation in the decay of B-mesons are the Belle and BaBar experiments – where B mesons are produced in electron-positron collisions using particle accelerators – the latter at the Stanford Linear Accelerator, and the former at an electron-positron synchrotron collider at KEK in Japan. The interaction points are surrounded by optimised detectors to watch the decay of the B-mesons created. When, say, a decays into some stuff, say a and a couple of leptons, the anti-reaction, a decaying into the corresponding antiparticles, will occur, but at a different rate.
The observation of these decay events inside these detector experiments, like LHCb and Belle, provides insights into the mechanism by which the symmetry is broken to the degree that it is.
The LHCb detector experiment on the LHC is intended to be very similar in nature to these existing experiments – with similar goals.
Not Even Wrong: LHC and Doomsday
Yes, you’ve heard it all before. Black holes, strangelets, and even attack from Nibiru.
I will not spent any time entertaining such things, which we’ve thoroughly dismissed as nonsense already, other than to look at the latest in a long line of rubbish anti-science claims.
Yesterday, a group of LHC critics filed a suit against CERN in the European Court of Human Rights, in Strasbourg . The authors of the suit are physicists, professors and students largely from Germany and Austria, who feel that the operation of the $10 billion Large Hadron Collider near Geneva, poses grave risks for the safety and well-being of the 27 member states of the European Union and their citizens.
Who are these authors? What are their qualifications? What are their arguments? Does their science stack up?
Bosenovas are a new risk theory in the suit, besides the better known Strangelets and Lowered Vacuum State theories. Unlike the others there is some experimental evidence for a Bosenova, but this phenomenon of implosion/explosion has only been produced in small groups of atoms of Rubidium-85 in an ultracold state, a Bose-Einstein Condensate.
What might occur at the LHC, is a new type of Bosenova from what amounts to a BEC used there as a coolant, an ultracold Superfluid Helium II, of about 60 metric tonnes in the LHC ring, and a further 60 tonnes of somewhat warmer Superfluid Helium I in refrigeration plants on the surface connected to the subterranean main ring. Whether possible or not is unknown, no experiments having been done by CERN to rule out the possibility, nor any theoretical model studies.
A bosenova is a very small, supernova-like explosion, which can be induced in a Bose–Einstein condensate (BEC) by changing the magnetic field in which the BEC is located, so that the BEC quantum wavefunction’s self-interaction becomes attractive. This is a poorly understood, very, very interesting phenomenon – but it’s not dangerous, and it’s of little relevance to the LHC.
This stuff is taken from this page…
But superfluid Helium II BEC is being used in great quantities as a coolant in certain nuclear reactors and particle accelerators.
The possibilities of a giant BEC bosenova produced in superfluid Helium II haven’t been investigated. The matter is urgent as 120 T of superfluid Helium II are being used at the Large Hadron Collider at Geneva, whose energies far surpass any other collider’s, not only beam energies, but RF applied, extreme Tesla Fields by superconducting magnets, and electrical energies equivalent to the consumption of Geneva…
“superfluid Helium II BEC”…. well, it’s just liquid helium. Liquid helium’s quantum-hydrodynamical properties are really cool indeed, but it’s just liquid helium. These days, liquid helium is routine technology.
We use LHe cryostats every day in scientific research, and technical applications…. cryostats for scientific experiments, superconducting niobium RF resonator cavities for particle accelerators, superconducting magnets for Nuclear Magnetic Resonance Spectrometers, and (N)MRI imaging machines at most major hospitals.
These are all based around liquid helium cryostats, and none of them ever lead to “Bosenova” explosions, despite being constantly irradiated by cosmic ray particle showers.
“Extreme Tesla fields”?? It’s called a magnetic field. (Usually, when you build a magnet, you do tend to get a magnetic field.) Why is a magnetic field referred to as a “Tesla field”? Is it an attempt to invoke the aura of mystical, magical, pseudoscience, superstition and suspicion that surrounds Tesla’s name?
Also… there’s no such thing as a liquid-helium-cooled nuclear reactor. Unless you’re talking about superconducting magnets in ITER… and it’s not even built yet.
What happens next at the LHC will be the next big experiment in a superfluid Helium II BEC. It’s not part of the design parameters, as physicists assume that the helium will be stable based on its use in the much smaller, much less powerful, up to 250 GeV per beam, RHIC collider in Long Island, NY. CERN’s interests lie in producing the Higgs boson at the LHC, perhaps micro black holes and quark-gluon plasma. Even in the much awaited CERN safety study released last month, there’s absolutely nothing on a possible bosenova implosion/explosion. Of course to test the safety of the enormous LHC to handle foreseen and unforeseen events you’d need another disposable one. But at least it is possible to subject Helium II to some of these high energies and hadron beams as a test. Not at the low energies of the RHIC, but at Fermilab’s Tevatron, currently the most energetic collider with 0.9 TeV per beam, though still far short of the power of the monster LHC at ordinary operating conditions of 7 TeV and ultimately 1,150 TeV collisions of lead ions at nearly twice light speed. Helium II could simply be used as a target by Tevatron beams to see what would happen, besides being exposed to high and fluctuating Tesla fields, ionized by electrical currents, subjected to some of the extreme conditions anticipated at the LHC.
Superconducting cables, superconducting magnets, or superconducting niobium RF cavities in LHe cryostats are already in widespread use around the world. They’re just auxiliary pieces of technology that are associated with the particle accelerator. The liquid helium is just needed to keep those superconductors at the appropriate temperature, and it’s got nothing to do with the particle interactions themselves, and it’s nowhere the actual particle collisions.
Deliberately, carefully twiggling the wavefunction of a Rubidium-87 BEC in order to induce a “bosenova” on purpose is a far cry from saying that a magnet inside a helium dewar can spontaneously explode.
There’s still a suit in the Hawaii courts to delay LHC startup because of safety concerns like black hole and strangelet production. Lately and since I first considered the possible dangers of superfluid helium in my article of March 7, 2008, ‘The Almost Thermonuclear LHC’, the plaintiffs, Dr Walter Wagner and Luis Sancho have announced they will seek an addendum to their suit to include bosenova risks at the LHC.
Oh yes, because they’re so credible. I’m surprised they don’t file an addendum to their lawsuit to include the risk of disruption of the van Allen belts, allowing the return of the Annunaki from the planet Nibiru.
CERN’s official LHC backgrounder, brochure and FAQ
I will probably post some more later. Until then, your comments and questions are fully welcomed, and will likely determine the direction of the next post.