World's Largest Supercooled Magnet Activated 171
An anonymous reader writes to mention a C|Net article about the activation of the world's largest superconducting electromagnet. Switched on today at Geneva's CERN lab, the experiment is part of the Large Hadron Collider (LHC) project. The magnet, called ATLAS, worked on its first start up. From the article: "In use, the magnet will be used to bend the paths of particles formed from the collision of protons or lead ions accelerated to near light speeds in 27km diameter subterranean contra-rotating circular beams. The ATLAS experiment is one of five in the LHC, and engages 1,800 scientists from 165 universities and laboratories in 35 countries."
Worlds largest bulk magnetic media eraser... (Score:4, Funny)
A faint "bwa ha ha ha... vhs tapes and floppy disks suck!" was heard from from the evil scientists' lair.
Oblig (Score:3, Interesting)
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Re:Worlds largest bulk magnetic media eraser... (Score:5, Funny)
I live inside the ring... (Score:3, Funny)
So far, so goo£%^$.... NO CARRIER
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It's taking a long time (Score:5, Funny)
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eek! (Score:1)
why (Score:4, Insightful)
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Well, they sure know their way around tubes...
Re:why (Score:5, Informative)
The magnet needs supercooling because a huge magnetic field is easier to achieve with a superconductor than with a conventional magnet.
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This is because we already know the mass of the particles (such as molecular and atomic io
Re:why (Score:5, Informative)
The LHA consists of a tube running through a series of magnets, a bit like a linear accelerator. The tube is bent into a circle so you can have the particles do multiple laps around the accelerator to increase their energy.
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Re:why (Score:5, Informative)
Here, have a look at this picture [fnal.gov] of a particle physics event (not from ATLAS but CDF at the Tevatron but the idea is the same). Lines in the circle are particle tracks, the two pink ones are very high momentum charged particles (in this case electrons). Notice how they are straight. As such we dont have a very good measurement of their momentum. The other grey lines are low momentum particles as they bend a lot since the radius of curvature is small.
Why do we want to measure the momentum of a particle? Well the Higgs boson (if it exists) will decay to 4 muons (basically heavy electrons) (nb: the Higgs can decay to other stuff but for a heavy higgs this is the cleanest signature and will be how its discovered). You want to measure the momentum of these muons and from that you can measure the mass of the particle that produced them. If you get a lot of events at a certain mass above what you expect from background, you've just discovered a new particle, likely to be the Higgs.
Re:why (Score:5, Informative)
I am not a particule physicist, but the particules need be accelerated and are 'pushed' by the magnets before being collided, so they need to circulate many times around the accelerator in order to get sufficient speed.
"A beam might circulate for 10 hours, travelling more that 10 billion kilometres, enough to get to the planet Neptune and back again. At near light-speed, a proton in the LHC will make 11 245 circuits every second."
What is the LHC power consumption?
It is around 120 MW which corresponds more or less to the power consumption for households in the Canton (State) of Geneva."
http://public.web.cern.ch/Public/Content/Chapters
> why does the magnet need to be super cooled?
To magnets are used also to maintain the beam within its path, and the requires huge amount of energy to create a magnetic field that is strong enough to prevent the beam to escape. These magnets are using a massive amount of power, and must be cooled down (a lot) do reduce their electrical resistance down to supraconductivity.
"In order to cool the magnets down to -193.16 C (pre-cooling), 10 080 tonnes of liquid nitrogen will be used. Afterwards, the refrigerators turbines will bring the helium temperature down to -268.7 C and fill the magnets with almost 60 tonnes of liquid helium. Once the magnets are filled, the refrigeration units will bring the temperature down to -271.3 C by lowering the saturation pressure - and therefore the temperature - of the liquid helium in a heat exchanger in contact with the static pressurized helium of the magnets' cold masses."
http://public.web.cern.ch/Public/Content/Chapters
http://en.wikipedia.org/wiki/Large_Hadron_Collide
For reference, the LHC will also use a massive computing Grid: http://www.cern.ch/LCG/ [www.cern.ch]
Romain.
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The accelerator does use magnets to contain the particles, just not this one.
The ATLAS experiment [wikipedia.org] is one of the detectors which use the output from the accelerator.
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http://atlas.web.cern.ch/Atlas/TCOORD/Activities/I nstallation/atlas_overview.gif [web.cern.ch]
These differents layers of detection gener
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As found on this [atlasexperiment.org] page, the magnet is used to measure the momentum of the particles. I'm not into physics, but I imagine it's a bit like rolling (equally sized) balls along a line, and then have a fan on the side trying to deflect the movement. A large momentum (and thus mass, assuming all the balls travel at the same speed) would lead to less deflection.
Impressive stuff (Score:3, Interesting)
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Re:Impressive stuff (Score:4, Informative)
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"They're waiting for you Gordon... in the test chamber"
(What is it with people in that series and emphasizing random words? "Wake UP! Wake up and smell the ASHESEHESSS....")
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The realy deep questions (Score:5, Interesting)
Re:The realy deep questions (Score:5, Informative)
The real understanding of this problem requires knowledge of Quantum Field Theory, but the gist of the problem is as follows:
All known matter particles (fermions) as well as the particles that mediates the weak force (the W and Z) behaves in experiments as if they have masses. However, if they actually do have masses the theory breaks down (it becomes non-renormalizable, and gives non-sensical answers such as "that decay have a branching ratio of 500%". It becomes a bit like sports-commentators, I guess).
The proposed solution to this conundrum, and the one the LHC and ATLAS will try to verify, sounds kind of like a lawyer finding a legal loophole when you first hear it. In essence it is: "All particles are really massless, but some of them behaves as if they have mass". The way to accomplish this is by the so-called Higgs Mechanism, in which particles acquire masses the same way that a light-weight guy walking in a waist-high pool will feel as much or more difficulty walking as a really fat guy walking on dry ground: All particles move around in a soup of Higgs particles and thus acquire the appearance of being massive due to their interactions with this Higgs-soup.
I thought it was kind of cheesy back when I first heard about it, but later I realised that similar effects already are known to happen elsewhere in nature, which kind of makes it more acceptible (for instance, those familiar with the Meissner effect for superconductors might recall how the otherwise massless photon acquires the appearance of mass inside superconductors due to the presence of a soup of electronic cooper-pairs).
But we will have to see when the LHC starts!
ps. I am actually a member of the ATLAS collaboration. Go magnets!
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This confirms what I've been saying all along... (Score:1)
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Oh so the Higgs-soup is kind of like phlogiston or something similar?
Strongest magnetic field or Physically Largest? (Score:1)
According to this [zdnet.com] article, the peak fields for this magnet are 3.9T; Is this the world's largest magnetic field, or just the largest magnet physically?
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Re:Strongest magnetic field or Physically Largest? (Score:4, Informative)
Dear Gregory,
I believe that the field of the ATLAS magnet is around 2 tesla, but the volume is vastly larger than an MIR magnet. Another experiment at CERN, which has a smaller volume than ATLAS has a field that reaches 4 tesla. In the LHC particle accelerator itself, the field in the magnets is around 9 tesla.
Regards, James Gillies
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How would that be possible? I thought that this Higgs particle was highly unstable and decays almost immediately. So where does the soup come from?
NB: I'm no expert.
Uncertainty principle (Score:2)
You need time to make a completely accurate energy measurement. At very short time scales, energy levels can be uncertain enough to be large enough to create particles.
These are called "virtual particles", even though they're as real as any other sort, simply confined to a temporary quantum fluctuation.
If you think this sounds like hocus-pocus, you have a heal
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-f
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Energy Consumption (Score:3, Funny)
This is just a part of Large Hadron Collider (Score:5, Informative)
http://public.web.cern.ch/Public/Content/Chapters
Re:This is just a part of Large Hadron Collider (Score:5, Informative)
Re:This is just a part of Large Hadron Collider (Score:4, Funny)
Suuuure! That's what you said the last time the Earth was destroyed.
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Suuuure! That's what you said the last time the Earth was destroyed.
According to the International Earth-Destruction Advisory Board (IDEAB) [qntm.org] the current Earth-Destruction Alert Level (EDA Level) is "green" which indicates that the earth has not been destroyed. Furthermore, the Current Geocide Count (CGC) is zero, indicating that the earth has not yet been destroyed in the past. (In the event of the Earth being destroyed, the CGC will be increased by one, to read "1".)
You must thus be mistaken.
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The LHC is designed to verify ma
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Sorry (Score:1, Funny)
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Finally! (Score:1)
car theft (Score:1)
Shutdown (Score:5, Interesting)
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Re:Shutdown (Score:5, Funny)
Oh wait
Tom
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But they do have extensive field-quench protection systems. (they need it, as its by far the biggest liquid helium installation in the world).
One way they protect themselvs is that they are well below the critical temperature for the magnet at the current density they use. They also use liquid helium evaporation cooled to about 2K. And they have huge venting tanks for quench protection.
The sublimation heat of helium is not that big, but they have 10s of t
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I once worked with a guy who used to maintain fairly large superconducting NMR magnets. According to him they procedure was essentially as follows Step 1: Connect wires to the magnet taking great care not to quench the magnet in the process (e.g. stop it super conducting). Step 2: Place a large resistive load between the wires and bleed off the stored energy.
Apparently you only screw up step one once.
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If you generate too much heat the situation goes exponentially out of control as the entire magnet rapidly heats up (as each portion o
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Helium is lighter that air and immediately goes to the ceiling. All that will happen is that the people will sound like Donald Duck for a sort time after a large amount helium is released into a room. You will want to stay away from the jet of escaping helium however, as it is VERY cold and will instantly freeze any appendage that gets in its way.
Superconducting wire in all mag
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In practice there is a resistor connected across the coils. The value of this resistor is such that it is large in relation to the total resistance of the coils when these are NOT superconducting. Since the resistance of the coils is zero when it is superconducting, all the current from the power supply flows through the coils and nothing through the resistor.
If the magnet or any part thereof becomes too warm to remain superconducting, some electronics detects this
MRI machine damage (Score:2)
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The magnet is superconducting, but the small shunt completing the circuit is heated to become a normal conductor while slowly pumping current in through some big-ass copper cables. Now in this case the copper cable connector had not been plugged in well enough, and as the field reached about 3T, the copper heated and brought the circuit out of superconductivity. The energy stored in the f
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The coils are short circuited - each barrel toroid is a very large loop of superconductor. A circuit with no resistance is, almost by definition, a short circuit. But, because the coils are superconducting, the current in them flows without dissipating. You can disconnect the power supply, and the current still flows. That's the beaut
Half true (Score:2)
A dissapating magnetic field is a moving magnetic field. What happens when you have a magnetic field is moving in relation to any conductors? That's right - you create a generator [wikipedia.org].
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Actually OPEN-ciruiting the coils would be much more fun. Such a magnet is a huge inductor and as such will want to keep whatever current is flowing in it constant through whatever resistance it can go through. If the circuit is opened, then there will be a monstrous arc through whatever path the current may find until all the energy stored in the magnetic field is dissipated.
Short circuiting such a superconducting coil would slow
Re:Shutdown (Score:5, Informative)
Re. Shutdown... and Natural Gas (Score:2)
The solar panels on my friend's WestFailia produce about 50 watts. On a sunny day he might have to wait an hour or so before he can run his toaster.
Seriously - tyring to put energy units into perspective is very necessary since most people (/.'s excepted) don't have a clue.
I couldn't find "jenni". Alas!
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In terms of energy cost, the amount stored in this 11Gj magnet would cost about $214 retail here in Oregon. That is quite a bit more than the average electric bill here. It comes to a little over 3000Kwh of electricity.
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Try http://jenni.web.cern.ch/jenni/BT.9Nov06.jpg [web.cern.ch]
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Actually it is because of the huge amount of ionizing radiation (mostly x-rays) produced when any high energy particle beam hits stuff. When this machinery is operating, the many feet of earth act as cheap and effective shielding to keep the operators and scientists in the control rooms safe. The energy in the beam as such is actually quite small. Safely dumping 11Gj of energy stored in the magnetic field is a far bigger challenge.
How Uncanny (Score:1, Redundant)
Strength ? (Score:1)
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Apparently the Lameness filter has a problem with straight forward answers.
4 8 15 16 23 42 (Score:1)
ATLAS webcams (Score:3, Informative)
Ah ha! (Score:4, Informative)
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Dude, I think you've been playing too much World of Warcraft.
World's Largest Supercooled Magnet Activated... (Score:1)
Monitor Troubles (Score:1)
atleast with photo (Score:1)
Field strength and other detials (Score:4, Informative)
I was wondering what the magnetic field strength of this magnet would be, but the FA is a light on details. But there's a pamphlet [cern.ch]!
Peak field strength for the barrel toroid magnet is 3.9 Tesla. And apparently it will take 30 days to cool the thing down with liquid helium to operating temperature.
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There is even a 20T magnet 30 meter away from me right now, but the volume of the bore is only the size of a can of coke.
The energy density goes square with the flux, but linear with the volume, so the size makes the magnet quite special.
Everytime I read about particle accelerators (Score:5, Funny)
I imagine a group of scientists standing at one point next to the tube with a hole, waiting and watching.
Only .5T... (Score:1)
The magnets generate a field of 0.5 Tesla (not as much as the magnets that manage the beam, but still pretty hefty!).
1800 scientists (Score:4, Funny)
That's going to be quite an author list when they finally publish...
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Abstract: The Authors have discovered a method to control The Universe.
Bad Headline? Welcome to Slashdot! (Score:2)
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