Posts Tagged‘cern’

Beyond the LHC: AWAKE.

The Large Hadron Collider has proven to be the boon to particle physics that everyone had imagined to be but it’s far from done yet. We’ll likely be getting great data out of the LHC for a couple decades to come, especially with the current and future upgrades that are planned. However it has its limit and considering the time it took to build the LHC many are looking towards what will replace it when the time comes. Trouble is that current colliders like the LHC can only get more powerful by being longer, something which the LHC struggled with at its 27KM length. However there are alternatives to current particle acceleration technologies and one of them is set to be trialled at the LHC next year.

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The experiment is called AWAKE and was approved by the CERN board back in 2013. Recently however it was granted additional funding in order to pursue its goal. At its core the AWAKE experiment is a fundamentally different approach to particle acceleration, one that could dramatically reduce the size of accelerators. It won’t be the first accelerator of this type to ever be built, indeed proof of concept machines already exist at over a dozen facilities around the world, however it will be the first time CERN has experimented with the technology. All going well the experiment is slated to see first light sometime towards the end of next year with their proof of concept device.

Traditional particle colliders work on alternating electric fields to propel particles forward, much like a rail gun does with magnetic fields. Such fields place a lot of engineering constraints on the containment vessels with more powerful fields requiring more energy which can cause arcing if driven too high. To get around this particle accelerators typically favour length over field strength, allowing the particles a much longer time to accelerate before collision. AWAKE however works on a different principle, one called Plasma Wakefield Acceleration.

In a Wakefield accelerator instead of particles being directly accelerated by an electric field they’re instead injected into a specially constructed plasma. First a set of charged particles, or laser light, is sent through the plasma. This then sets off an oscillation within the plasma creating alternating regions of positive and negative charge. Then when electrons are injected into this oscillating plasma they’re accelerated, chasing the positive regions which are quickly collapsing and reforming in front of them. In essence the electrons surf on the oscillating wave, allowing them to achieve much greater velocities in a much quicker time. The AWAKE project has a great animation of the experiment here.

The results of this experiment will be key to the construction of future accelerators as there’s only so much further we can go with current technology. Wakefield based accelerators have the potential to push us beyond the current energy collision limits, opening up the possibility of understanding physics beyond our current standard model. Such information is key to understanding our universe as it stands today as there is so much beauty and knowledge still out there, just waiting for us to discover it.

 

Superconducting Magnetic Shield for Astronauts of the Future.

You’d think that long duration space travel was something of a solved problem, given the numerous astronauts who’ve spent multiple months aboard the International Space Station. For some aspects of space travel this is correct but there are still many challenges that face astronauts who’d venture deeper into space. One of the biggest challenges is radiation shielding as whilst we’ve been able to keep people alive in-orbit they’re still under the protective shield of the Earth’s magnetic field. For those who go outside that realm the dangers of radiation are very real and currently we don’t have a good solution for dealing with it. The solution to this problem could come out of research being done at CERN using a new type of superconducting material.

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The material is called Magnesium diboride (MgB₂) and is currently being used as part of the LHC High Luminosity Cold Powering project. MgB₂ has the desirable property of having the highest critical temperature (the point at which it becomes superconducting) of any conventional superconducting materials, some −234°C, about 40°C above absolute zero. Compared to other conventional superconductors this is a much easier temperature to work with as others usually only become superconducting at around 11°C above absolute zero. At the same time creating the material is relatively easy and inexpensive making it an ideal substance to investigate for use in other applications. In terms of applications in space the Superconductors team at CERN are working with the European Space Radiation Superconducting Shield (SR2S) project which is looking at MgB₂ as a potential basis for a superconducting magnetic shield.

Of the numerous solutions that have been proposed to protect astronauts from cosmic radiation during long duration space flight a magnetic shield is one of the few solutions that has shown promise. Essentially it would look to recreate the kind of magnetic field that’s present on earth which would deflect harmful cosmic rays away from the spacecraft. In order to generate a field large and strong enough to do this however we’d have to rely on superconductors which does introduce a lot of complexity. A MgB₂ based shield, with its lower superconducting temperature, could achieve the required field with far less requirements on cooling and power, both of which are at a premium on spacecraft.

There’s still a lot of research to go between now and a working prototype however the research team at S2RS have a good roadmap to taking the technology from the lab to the real world. The coming months will focus on quantifying what kind of field they can produce with a prototype coil, demonstrating the kinds of results they can expect. From there it will be a matter of scaling it up and working out all the parameters required for operation in space like power draw and cooling requirements.

It’s looking good for a first generation shield of this nature to be ready in time for when the first long duration flights are scheduled to occur in the future, something which is a necessity for those kinds of missions. Indeed I believe this research is certain to pave the way for the numerous private space companies and space faring nations who have set their sights beyond earth orbit.

The Universe’s Strange Preference for Matter.

In the beginning, the one where time itself began, the theory goes that matter and antimatter were created in equal amounts. When matter and antimatter meet they annihilate each other in a perfect transformation of matter into energy which should have meant that our universe consisted of nothing else. However, for some strange reason, the universe has a small preference for matter over antimatter, to the tune of 1 parts in 10 billion. This is why our universe is the way it is, filled with billions of galaxies and planets, with the only remnant of the cataclysmic creation being the cosmic microwave background that permeates our universe with bizarre consistency. The question of why our universe has a slight preference for matter has puzzled scientists for the better part of a century although we’re honing in on an answer.

ALPHA Antimatter TrapIf you had the ability to see microwaves then the night sky would have a faint glow about it, one that was the same no matter which direction you looked in. This uniform background radiation is a relic of the early universe where matter and antimatter were continuously annihilating each other, leaving behind innumerable photons that now permeate every corner of the known universe. What’s rather perplexing is that we haven’t observed any primordial antimatter left over from the big bang, only the matter that makes up the observable universe. This lack of antimatter means that, for some reason or another, our universe has an asymmetry in it that has a preference for matter. Where this asymmetry lies though is still unknown but we’re slowly eliminating its hiding spots.

The Antihydrogen Laser Physics Apparatus (ALPHA) team at CERN has been conducting experiments with antimatter for some time now. They have been successfully capturing antiprotons for several years and have recently moved up to capturing antihydrogen atoms. Their approach to doing this is quite novel as traditional means of capturing antimatter usually revolve around strong magnetic fields which limit what kinds of analysis you can do on them. ALPHA’s detector can transfer the antihydrogen away from their initial capture region to another one which has a uniform electric field, allowing them to perform measurements on them. Antihydrogen is electrically neutral, much like its twin hydrogen, so the field shouldn’t deflect them. The results have shown that antihydrogen particles have a charge that’s equivalent to 0, showing that it shares the same properties as its regular matter brethren.

This might not sound like a much of a revelation however it was a potential spot for the universe’s asymmetry to pop up in. Had the charge of the antihydrogen atom been significantly different from that of hydrogen it would’ve been a clue as to the source of the universe’s preference for matter. We’ve found that not to be the case so it means that the asymmetry exists somewhere else. While this doesn’t exactly tell us where it might be it does rule out one possibility which is about as good as it gets in modern science. There’s still many more experiments to be done by the ALPHA team and I have no doubt they’ll be significant contributors to modelling just similar matter and antimatter are.

 

The Higgs is Here, The Higgs is Here!

You know what I most enjoy about science? The ever changing, always raging debate about how our models can be improved beyond what we currently have. Our scientific history is filled with models that made sense at the time with the knowledge we had then, only to be torn asunder by some new finding that forces us to rethink the way in which we modelled the observable universe before us. What I find most exciting are the times when we’re wrong as one experiment going completely awry can provide the required insight to shift our perspective considerably. Equally as exciting though is the prospect that we’ve modelled something almost perfectly and our experimental evidence confirms it.

Today we witness the latter with the Large Hadron Collider announcing that they’ve discovered a new particle and it looks suspiciously like the Higgs Boson:

“We observe in our data clear signs of a new particle, at the level of 5 sigma, in the mass region around 126 GeV. The outstanding performance of the LHC and ATLAS and the huge efforts of many people have brought us to this exciting stage,” said ATLAS experiment spokesperson Fabiola Gianotti, “but a little more time is needed to prepare these results for publication.”

“The results are preliminary but the 5 sigma signal at around 125 GeV we’re seeing is dramatic. This is indeed a new particle. We know it must be a boson and it’s the heaviest boson ever found,” said CMS experiment spokesperson Joe Incandela. “The implications are very significant and it is precisely for this reason that we must be extremely diligent in all of our studies and cross-checks.”

If you’re scratching your head as to why this discovery is so significant here’s a run down on what the Higgs Boson is in terms of the standard model of particle physics:

For the TLDR crowd the discovery of the Higgs Boson would fit our current model for understanding why particles have mass. Should the Higgs Boson not exist then our current understanding would be invalidated and we’d have to start testing other theories so our model could be made more accurate. For the most part there’s overwhelming evidence to support the standard model thanks to the previous work of other particle accelerators but the Higgs Boson represents the keystone of the whole model. Without it the rest of it needs a whole lot more explanation in order to make it work effectively.

Now whilst this is being lauded as the discovery of the Higgs Boson, and in all likelihood it is, there’s a non-zero chance that the CMS and ATLAS detectors at CERN have actually discovered another new particle that isn’t the Higgs Boson. That would be extremely interesting in and of itself as it would mean that the Higgs Boson, if it exists at all, would more than likely be at some mas even higher than first predicted. From what I can remember the current mass of the Higgs was on the upper limit of the LHC’s capabilities so if this turns out to be some kind of other particle, one that doesn’t exclude the Higgs from existing, we’d probably need to construct another particle accelerator in order to be able to detect it. That or the LHC would need to be upgraded which I admit is far more likely.

Regardless of the true nature of this new particle its discovery is something to get excited about as no matter what it is it means big things for the world of particle physics. The findings won’t see radical technology change or anything like that but it does mean we’re honing in on some of the fundamental aspects of our universe, something which I find incredibly thrilling. The next few months of data verification and probing the properties of this new particle will be a very interesting time and I can’t wait to hear more about this new boson.

LHC Powers Up, Earth Still Here.

Yesterday marked a huge achievement for CERN and the team working on the Large Hadron Collider. After almost a year of delays after a catastrophic incident that damaged 2 sectors and caused 6 tons of helium to be lost they have successfully circulated 2 beams around the LHC. This of course let them test the entire reason they built the thing in the first place, smashing things together:

Geneva, 23 November 2009. Today the LHC circulated two beams simultaneously for the first time, allowing the operators to test the synchronization of the beams and giving the experiments their first chance to look for proton-proton collisions. With just one bunch of particles circulating in each direction, the beams can be made to cross in up to two places in the ring. From early in the afternoon, the beams were made to cross at points 1 and 5, home to the ATLAS and CMS detectors, both of which were on the look out for collisions. Later, beams crossed at points 2 and 8, ALICE and LHCb.

“It’s a great achievement to have come this far in so short a time,” said CERN1Director General Rolf Heuer. “But we need to keep a sense of perspective – there’s still much to do before we can start the LHC physics programme.”

Now we all know the hype around the LHC and how it has the “potential” to create a black hole that will destroy the earth. Whilst its been debunked many times over I’d just like to re-iterate it here, we’re not in any danger from the LHC or the particles it may create. Even though the energy in these collisions seems huge it is in fact quite small, about that of clapping your hands or a flying mosquito, concentrated into a very tiny space. Even if a black hole were to be created it would either evaporate almost instantly due to hawking radition or blaze through the earth where it would then take about 10 octillion (that’s a 1 followed by 28 zeros) to consume the entire earth. I’d be worried about the universe spontaneously collapsing in on itself than a small black hole created by the LHC consuming the earth.

So many people know what the LHC is but not what it was designed for. It does have several goals listed although there’s really only one that gets me all giddy:

  • Is the Higgs mechanism for generating elementary particle masses via electroweak symmetry breaking indeed realised in nature? It is anticipated that the collider will either demonstrate or rule out the existence of the elusive Higgs boson(s), completing the Standard Model.
  • Is supersymmetry, an extension of the Standard Model and Poincaré symmetry, realised in nature, implying that all known particles have supersymmetric partners? These may clear up the mystery of dark matter.
  • Are there extra dimensions, as predicted by various models inspired by string theory, and can we detect them?

The Higgs-Boson is an elusive beast as its the only particle in the standard model that has only been inferred theoretically, it has never been observed. Its discovery would round out the model and serve as a solid basis for the holy grail of physics, a theory for everything. Although this would be all well and good (and really, it is to be expected that we will see a Higgs-Boson) it would probably be more significant if the exact opposite happened. The greatest moments in science have stemmed from carefully prepared experiments behaving in ways that no one predicted, challenging our current thinking and forcing us to look back at our previous work. Whilst I will sing the LHCs praises from the rooftops should they find the Higgs-Boson you can be sure that I’ll be cackling with a mad sense of glee if they prove it does not exist.

While we’re still a ways off from doing real hard science with the LHC it’s great to see them hitting such a significant milestone. It’s hard to believe that the project, which has been going for over 15 years, is on the cusp of performing some of the most radical science to date. Really its a testament to what humanity is capable of and how far we’re willing to go just to satisfy our curiosity.