Fermilab magnet failure pushes back research goals

Published on March 31st, 2007

You live and you learn.

On Tuesday, March 27, there was a serious failure in a high-pressure test at CERN of a Fermilab-built “inner-triplet” series of three quadrupole magnets in the tunnel of the Large Hadron Collider. The magnets focus the particle beams prior to collision at each of four interaction points around the accelerator.

A full investigation of the failure is underway, but preliminary indications are that structures supporting the inner “cold mass” of one of the three magnets within its enclosing cryostat broke at a pressure of 20 atmospheres, in response to asymmetric forces applied during the test. Such forces are expected on occasion during normal operation of the LHC. The failure does not concern the magnets or the cold masses themselves, but rather their assembly in the cryostat.

Basically this means that we are still learning how to manage superconducting structures under stresses most people barely believe, much less understand.

11 users responded in " Fermilab magnet failure pushes back research goals "

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# 1 noname said, on March 31st, 2007 at 10:10 pm

B.S. “Basically this means that we are still learning how to manage superconducting structures under stresses”

I was working on a 4T 15 ton Oxford MRI self shielding super conducting magnet back in 1988, in New Jersey. I had the lovely “privilege” to periodically fill these beasties with LN2 (in the outer cryostat) and liquid He (in the inner cryostat that held the ~250 amps of coil current).

During one of these fills, I had the pleasure of quenching the beast. It was like standing on a Volcano. During the incident I had a flash of the incident where a technician was impaled on a control rod when blown to the ceiling of the containment dome during “routine” preparation for the SL-1 reactor start-up many years back.

The concern they are testing for, is when these coil quench, all that LN2 and liquid He turns into gas. With out proper means of venting (sometimes the ports ice up and clog) you have a bomb. A common reason a (but not exclusive) superconducting coil quenches is when part of the coil exceed it’s critical temperature. There are various means and ways this happens. Quenching is not routine or normal by design.

Yes, it is very likely 20 atmospheres if not more can be expected during a coil quench. However, to say “on occasion during normal operation” is B.S.

Quenching is never normal, it can easily destroy/melt the superconducting coil, damage equipment or result in injured or asphyxiated personal. To believe anything else is dangerous.

All the various stresses and sources are very well understood and can be easily modeled. It is simply B.S. to say we are still learning, maybe for Smartalix. It may be new to the firm contracted to build the superconducting quads, but it’s certainly not new to the engineering or the science community at large. Plenty of software, science and companies exists to make this work right and safely the first time.

This is just a typical and routine example of poor oversight allowing either poor weld, construction or design. Don’t be fooled by “this is complicated high tech mobo jumbo”

B.S.

# 2 BubbaRay said, on March 31st, 2007 at 10:31 pm

SmartAlix, thanks for the post. Saw this very early Fri. morning and it’s now broken heart time.

Think of the advances in pure research we could be doing right now if the Superconducting Supercollider hadn’t been canned by our shortsighted govt. What a setback. Now using a bubbaism: DANG!

We’ve a long way to go uniting quantum mechanics and general relativity, and this could be a great step. Bring me the Higgs boson!

From WIki: Elementary particle masses, and the differences between electromagnetism (caused by the photon) and the weak force (caused by the W and Z bosons), are critical to many aspects of the structure of microscopic (and hence macroscopic) matter; thus, if it exists, the Higgs boson has an enormous effect on the world around us.

I got your cheap green energy right here, if someone would just keep funding the research. Microcents on the dollar….

# 3 BubbaRay said, on March 31st, 2007 at 10:34 pm

#1, noname, well done. Thanks. Hope you had a Rolex or some other way of keeping time…

# 4 Smartalix said, on April 1st, 2007 at 5:41 am

If we are still having problems, we are still learning. If we are simply learning not to cut corners or to be really, really careful it is still learning. This setback was not caused because we have made the construction and management of such a facility routine.

I never say, “this is complicated high tech mobo jumbo”. If you read my posts here you will know that I am a hig-tech evangelist. I did say that the facility deals with science many lay people don’t understand, but that is what high science is all about. I did not say the scientists involved don’t.

# 5 MikeN said, on April 1st, 2007 at 6:00 am

Are these guys using taxpayer money for all this?

# 6 Noname said, on April 1st, 2007 at 1:12 pm

#3, Never had a Rolex, I was wearing a Casio Digital Watch, they don’t magnetize. Also, if you want to keep your credit cards, don’t bring them near one of these beasties.

I got the Casio Digital Watch from my father, nomore:( Please see “Fairies Are Real! Mummified Remains Found In England!” Post #26.

# 7 BubbaRay said, on April 1st, 2007 at 9:56 pm

1,6 noname, Probably too late to post, but just how many Oersteds are you subjected to on a daily basis? Just curious, since my watch is only good to 1000 Oersted and working on large CC ’scopes / drives always makes me nervous.

Thanks for the posts !!

# 8 noname said, on April 1st, 2007 at 11:05 pm

I would say typically ~0.3 oersteds, the Earth magnetic field.

Although I do routinely work with multiple particle accelerator(s) that have an Analysing Magnet for Isotope/Mass separation; I haven’t bothered to measure it with our gauss meter.

As originally noted in #1, at the time I was working with a 4 Tesla (40,000 gauss) super conducting magnet.

# 9 BubbaRay said, on April 1st, 2007 at 11:50 pm

8, noname, remind me to have all my fillings replaced with ceramics before I come to visit

In 1994, the International Commission on Non-Ionizing Radiation Protection (ICNIRP) published guidelines for exposure to static magnetic fields [50]. For the general public the magnetic field exposure standard is 40 mT for continuous exposure, except for persons with cardiac pacemakers and other implanted electronic devices, where the standard is lower (0.5 mT). For occupational exposure, the standard is 200 mT for continuous exposure, 2000 mT for short-term whole-body exposure, and 5000 mT for exposure to arms and legs.

Quoted from this link: http://tinyurl.com/33asdr

# 10 noname said, on April 2nd, 2007 at 6:11 pm

I am not a regulatory expert, and this was some time ago, but not all your numbers sound right. Todays patients are routinely put in 1.5T magnets for NMR imaging.

The 4 T magnet was for a Full Body Nuclear Magnetic Resonance Imager. At the time the 4 T magnet was experimental. Because it was so strong, to keep it’s effective hospital footprint small it was selfshielding.

I never went into the bore of this magnet, but I was told if people move their head they can experience and some complained of various sensations, like metalic tastes, flashes in their sight… Your not supposed to move during one of these exams.

Yes we had postings and a cardiac pacemaker no pass line at a regulated and measured magnetic strength curve draw around the area/magnet.

A 4T magnetic field is desirable because it can obtain a lower Signal to Noise signal which is important for image quality. This is useful for an image with better contrast and resolution enabling doctors better contrast and a better chance of picking out tumours and such.

No reported harm is caused by the eddie currents that set-up in a persons body in a 4T field or for that matter the more common 1.5T. Eddie currents can stimulate nerves and the like, giving various sensations.

Beside the pace maker no pass line, the other regulatory concern was how much RF power a persons body is subjected to during an exam. Like microwaving a pot roast, a person body heats up during a NMR exam. However the frequency used is far from ideal for heating someone or water up. Still the equipment has special interlock circuits to ensure patients are very well protected.

Today 1.5T magnets are commonly used in NMR. If it was me I would never use the many open body imagers, as they use permanent magnets and less of a magnetic field. These tools have inherently worse S/N and poorer image contrast then a 1.5T superconducting magnet, where you are slide into the bore.

# 11 BubbaRay said, on April 2nd, 2007 at 11:20 pm

Well, I know it’s late and totally off topic, but what the heck.
10, noname, the numbers weren’t mine, just reference material from the url posted above. 4T is a monster magnetic field, and only in the event of a medical scan would I be willing to subject myself to it. In your line of work, I just hope that your 0.3 Oersted everyday exposure is spot on, with perhaps a very few limited exposures to much more. Perhaps less dangerous than friends of mine that work in nuke plants and wear rad badges. Any badges for magnetic exposure? Any worries? Will my 1000 Oersted resistant watch survive your environment? Darn, I’m tired of waiting on this computer to stack images from the 41 cm scope…. forgive the waste of bandwidth.

Thanks for the post.

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