LHC Magnet Test Failure

[MelissaSweet]

See: http://user.web.cern.ch/user/QuickLinks/Announcements/2007/LHCInnerTriplet.html" [Broken]

What's the latest news on the LHC? How bad is the damage? How long will the delay be?

 

[EL]

There's an updated version:
http://user.web.cern.ch/user/QuickLinks/Announcements/2007/LHCInnerTriplet_1.html

The goal at CERN and Fermilab is now to redesign and repair the inner triplet magnets and, if necessary, the DFBX without affecting the LHC start-up schedule.

 

[ZapperZ]

Still, none of these are as descriptive as the one reported in http://www.nature.com/news/2007/070402/full/070402-3.html".

Loud bang

The noise was loud enough for safety officials to demand that those present have their hearing checked. All have since been given the all clear.

Our division here has a large contingent that was responsible for many aspect of the ATLAS detector at the LHC. Most didn't think that this would cause a major delay in the test phase because the magnets are not exactly needed for the particle beam phase. They will be needed when they actually do the colliding.

Zz.

 

[humanino]

I am quite fascinated by this event. How could CERN and FermiLab communicate so fast ? This seems a major mistake to me. I heard some people say "FermiLab is trying to sabotage CERN, so they can find the Higgs, or any other discovery they could, before LHC starts". Of course, being myslef in the world of research, I can see how fool and plain wrong this idea is, for very many reasons. But to the large public...

 

[ZapperZ]

I am quite fascinated by this event. How could CERN and FermiLab communicate so fast ? This seems a major mistake to me. I heard some people say "FermiLab is trying to sabotage CERN, so they can find the Higgs, or any other discovery they could, before LHC starts". Of course, being myslef in the world of research, I can see how fool and plain wrong this idea is, for very many reasons. But to the large public...

That "sabotage" scenario is totally out of the question. Fermilab has a reputation to maintain, and the last thing they want is for the whole LHC to dump on them for being the source of the delay. Not only is this embarrassing, but it is also a PF nightmare.

When something like this is made, not only does it involved an unbelievable complicated design, it also involves a whole lot of external contractors and consultants. This is because this is an engineering project that requires the expertise of many outside companies, especially with regards to supplying the necessary material. It is one of such material from an external supplier that appears to not have conformed to some standard that may have led to the failure. We don't know yet for sure and a lot of review and investigations will be done.

Zz.

 

[magnetar]

Bursting Magnets May Delay CERN Collider Project
http://english.cri.cn/2906/2007/04/06/189@213092.htm

 

[neutrino]

Calculational Errors Caused Magnet Failure

The article ends on a controversial note:

Coincidentally, Fermilab stands to gain most from delays at Cern. Its researchers also operate a rival but less powerful particle accelerator, the Tevatron.

Fermilab staff are pushing the Tevatron to ever-higher energies hoping that they might find the Higgs boson before the LHC switches on. An LHC researcher said: “Ironically, this delay could be all they need.”

 

[ZapperZ]

The reason why I am dismissing such devious acts is because this is not the first time Fermilab and CERN have collaborated with each other and provided technical support. Not only that, there are many institutions that have vested interest in both the Tevatron and LHC. Our division here have people who work at both the CDF detector at the Tevatron and the ATLAS detector at the LHC. While the Fermilab and CERN do compete in some aspects of first discovery, there have been more instances of collaboration. If not, CERN would be out of their minds in having Fermilab build one of the major component of their system. Would you let your "enemy" do that?

Zz.

 

[FredGarvin]

Here's an article with some more detail to it:
http://www.fnal.gov/pub/today/20070329_page01.html

And a recent update:
http://www.fnal.gov/pub/today/20070403_page01.html

From a mechanical standpoint, I would really like to see the mode of failure of the supports. I have worked with similar material. It's pretty stout, but I have no idea as to the magnitudes of the forces involved. Does anyone have a swag?

 

[Ballon]

Failure ? I believe this could happen...however, how safe are we with "location" that are stocking antimatters anti-proton ? The energy magnitude is about 50x Atomic bomb matters to energy conversion when anti-matters react with their counter matters (this is very efficient)...hope that the magnets that participate on the "levitation" of the "stock" will not fail.

 

[Mk]

It's safe, don't worry about it, and there's not actually that much of it made.

 

[abbottsys]

I'm sure CERN and Fermilab will get this fixed quickly. Engineering wise it's probably a minor deal. Perhaps the only long term impact will be to Fermilab's reputation. I can see future generations of physicists (hopefully with many significant LHC discoveries under their belt) telling this story to their students over coffee.

 

[AlphaNumeric]

Failure ? I believe this could happen...however, how safe are we with "location" that are stocking antimatters anti-proton ? The energy magnitude is about 50x Atomic bomb matters to energy conversion when anti-matters react with their counter matters (this is very efficient)...hope that the magnets that participate on the "levitation" of the "stock" will not fail.

That is precisely why they run a huge series of extremely tough tests (well beyond what an actual collider run would involve), so that they know when they start introducing volatile materials into the ring it's going to be safe.

Also, you are grossly exaggerating the destructive power of the antimatter produced at CERN. A 1 kT explosion is equivalent to 4.2TJ of energy which is the direct conversion of about 50 milligrams of material. While 1kT is enough to decimate CERN, typical nukes are upwards of 50kT and as high as 200MT, 200,000 times as powerful (5kg turned into energy!). The entire sum of ALL antimatter ever made is less than 1g. To make 5kg would cost more than the entire world's GDP and while CERN has good funding, it's not that good.

The antimatter is made pretty much on demand, stored for only a few hours or days at most (ie they don't have tanks of it sitting around right now waiting for it to be needed), and even then the quantities involves are trillions of particles which equates to trillionths of a gram. An antimatter containment leave would cause a radiation spike and maybe a room to be destroyed, but the energies involved are less than a gallon of petrol, by several orders of magnitude.

Antimatter is just too hard to make in vast quantities to be a dangerous substance on a large scale (at present at least). More danger for CERN comes from the problem highlighted in this thread, things like the supermagnets going 'normal' and dumping their energy into heat too fast.

 

[ahrkron]

Also, the LHC will not be accelerating antimatter. The collisions are between two beams of protons (it is at Fermilab's Tevatron that protons and antiprotons are used).

 

[ahrkron]

In terms of the energy contained in the beam, according to http://public.web.cern.ch/Public/Content/Chapters/AskAnExpert/LHC-en.html [Broken],

"The total energy in each beam at maximum energy is about 350 MJ, which is about as energetic as a 400 t train, like the French TGV, traveling at 150 km/h. This is enough energy to melt around 500 kg of copper. The total energy stored in the LHC magnets is some 30 times higher (11 GJ)."

 

[mormonator_rm]

Also, the LHC will not be accelerating antimatter. The collisions are between two beams of protons (it is at Fermilab's Tevatron that protons and antiprotons are used).

I was under the impression that the LHC would be colliding beams of heavy ionized nucleii accelerated up to 1150 TeV. Is my impression incorrect?

 

[Mr.Brown]

They also want to do that but it´s not the main purpose of the lhc i think :)

 

[mormonator_rm]

They also want to do that but it´s not the main purpose of the lhc i think :)

Well, I figured that is the only way to generate the energies they will need to find the elusive Higgs boson, if it exists...

 

[ahrkron]

I was under the impression that the LHC would be colliding beams of heavy ionized nucleii accelerated up to 1150 TeV. Is my impression incorrect?

There will also be heavy ion collisions, but most of the time (I think on the order of 80 to 90%) it will be running in a proton-proton mode.

One of the main goals of the experiment is the search for the Higgs, for which a more convenient environment is provided by the less complicated proton-proton interaction.

 

[ahrkron]

Well, I figured that is the only way to generate the energies they will need to find the elusive Higgs boson, if it exists...

The problem is that total the energy in the havy ion collisions is shared among all the protons and neutrons on each ion nucleus, while the important quantity to make a Higgs is the energy of the two particles that interact strongly.

Think of each heavy ion nucleus as two bags of marbles (each marble being a quark). The total energy of colliding two bags can be quite high just because there are a lot of them; however, to produce a high mass particle, what matters is the average energy of the two marbles that hit against each other the hardest.

Also important in the search is the complexity of the event.

To give you some context: the cleanest collider experiments are those that collide electrons vs positrons because they are elementary particles. On the other hand, in Fermilab and LHC, the proton-(anti)proton collisions are much more complex because protons contain three quarks each (plus a gluon field); as a result, one proton-proton collision produces significantly more particles, the paths and identities of which need to be disentangled in order to learn anything from the initial collision.

A single pp collision may produce on the order of hundreds of particles; if, instead of pp, you collide bags of protons against each other, the mess is a much harder one to understand.

(but it is also an important one to study on its own merit, since you can there study the behavior of a sea of quarks and gluons)