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Restart of Large Hadron Collider At CERN
Taco Cowboy contributes this news from the BBC: After a two-year hiatus the LHC (Large Hadron Collider ) at CERN has been restarted. For the past two years an upgrade program was carried out for the LHC. Due to the upgrade, the LHC is enjoying a double dose of energy, as compared to its previous self before the upgrade. Particle beams have now travelled in both directions, inside parallel pipes, at a whisker below the speed of light.
Actual collisions will not begin for at least another month. Currently the protons are being injected at a relatively low energy to begin with. But over the coming months, engineers hope to gradually increase the beams' energy to 13 trillion electronvolts: double what it was during the LHC's first operating run. The experiment teams have already detected 'splashes' of particles, which occur when stray protons hit one of the shutters used to keep the beam on-track. If this happens in part of the pipe near one of the experiments, the detectors can pick up some of the debris. ... Debris from the tiny but history-making smash-ups might contain new particles, or tell-tale gaps betraying the presence of dark matter or even hidden dimensions. But first we need collisions — due in May at the earliest — and then a steady torrent of data will make its way to physicists around the world, so that the massive analysis effort can begin."
So far the beams are just at the injection energy of 450 GeV from the SPS and you can see some splash event in ATLAS here. The real test will be when they ramp the magnets up to 11kA currents for the 6.5 TeV beams. Hopefully this time our understanding of the universe will break before the machine.
One goal is to better understand the properties of the HIggs boson by making lot more of them. This will surely happen. There are a bunch of similar things where they just want more data to get details of something already discovered.
After that, the biggest target is supersymmetry. This is a purely theoretical notion (at present) which would offer a nice explanation for one of the major mysteries of current particle physics -- why particles like the Higgs are as light as they are. At the moment we have a bunch of equally "natural" theories in which Higgs masses range from little or nothing to massively more than they are now. Hitting a value this close to zero by chance is unaesthetic and experience suggests that when something like this happens there is usually a deeper explanation. Supersymmetry is a candidate for such an explanation.It would predict a whole slew of new particles, the lightest of which might be stable and might be within reach of the new LHC. They also might make up some or all of the "dark matter" which seems to make up most of the Universe.
The dark matter is also a target in its own right. Even if it isn't made of supersymmetry particles, it might be made of some other kind of particle light enough for the LHC to make some.
Then there are more exotic conjectures around like extra dimensions and dark energy particles wjich might show up.
Wat do u mean unaesthetic.
Pretty much what it says. The theory that relates all the existing particles ("The standard model") doesn't predict a mass for the Higgs boson, it's a number you have to measure and put into the theory. The theory does suggest limits -- it can't be less than zero or more than about a million million million times what it is. So it's a bit like finding something that could in principle be anywhere on a line from New York to San Fransisco but happens to be less than one atomic diameter from the New York end of the line. It could be chance but it doesn't feel right. That "not feeling right" is what I mean by unaesthetic.
Experience in physics is that things that "don't feel right' in this way usually hint at a deeper explanation which we don't understand. This one might not, but it seems worth looking.