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Originally Posted by Warren Platts
According to my calculations, one metric ton of liquid helium is about 8,000 liters (~ 2,000 gallons). What a mess.

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Originally Posted by Neverfly

OK, you better check them out:

Code:
```1,000 kg     1,000 gm     cm3        in3         gal
-------------------------------------------------------  =  2,000 gallons
kg      0.125 gm   16.39 cm3   231 in3```

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Originally Posted by tdvance
it's funny to call the "fire brigade" when the magnets heat up to less than 100 degrees (C) below (not absolute) 0. I assume the "by 100 degrees C" from, presumably, liquid-helium temperature, is not a misstatement, of course!
I'd guess not. The fire brigade have the necessary breathing apparatus and dangerous-materials handling skills. When you get even a moderate quench, from the helium coolant in a medical MRI scanner for instance, you quickly lose breathing air as the helium boils and rapidly displaces everything else.
I was once present during the commissioning of a new medical MRI, before the emergency ventilation was tested and working. There was a large temporary sign on the wall, reading "In case of helium quench, throw chair through window glass."

Grant Hutchison

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Dr. Hutchison, I know we don't talk to each other much these days, but I must agree that 2,000+ gallons of liquid helium is not something to be taken lightly.

5. Given its density, it's hard to take liquid helium heavily.

6. Originally Posted by mike alexander
Given its density, it's hard to take liquid helium heavily.
Good one!

7. Anyhow, of any liquid spilled, I can't think of one that would make less of a mess than liquid helium. If it was just a leak, not some catastrophic failure, I doubt there would have been any liquid helium around at all; it would just rapidly evaporate.

There's a 1,000 liter tank of liquid nitrogen outside our lab and it doesn't bother me. Overall, a lot safer than a tank farm of high-pressure cylinders.

8. Problem is: how frequently this kind of problem is expected to occur? If operation at low energy can do that, what´s gonna happen when the real thing starts?

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Originally Posted by Argos
Problem is: how frequently this kind of problem is expected to occur? If operation at low energy can do that, what´s gonna happen when the real thing starts?

Good question. I would (and the scientists do too) hope that it won't happen much, if at all. It's got to be an expensive loss, both in material and lost testing time. With a project this huge, you've got to expect a few failures to occur.

There's thousands of tons of hardware that's expected to work within extremely tight margins. As witnessed, one small problem can turn into a huge one real fast.

10. Originally Posted by Argos
Problem is: how frequently this kind of problem is expected to occur? If operation at low energy can do that, what´s gonna happen when the real thing starts?
The magnets haven't been trained up to their full power yet, so my understanding is they are expected to be a bit unstable. The "training" process sounds like it anneals defects out of the superconductor material, involving repeatedly deliberately raising the field to the point where quenching occurs, then re-cooling of the magnets and starting over, to allow them to reach higher field strengths. I would expect un-trained magnets to be more sensitive to stray particles and other quench causes as well.

11. Originally Posted by Argos
Problem is: how frequently this kind of problem is expected to occur? If operation at low energy can do that, what´s gonna happen when the real thing starts?
Probably not too likely. From what I can glean, this is a case of "infant mortality." That's a phrase used in construction/manufacturing to indicate the very early and premature failure of a component, usually from a manufacturing defect.

12. CERN Press Release: LHC re-start scheduled for 2009 (2008 September 23):

The time necessary for the investigation and repairs precludes a restart before CERN’s obligatory winter maintenance period, bringing the date for restart of the accelerator complex to early spring 2009. LHC beams will then follow.
===

Originally Posted by Argos
Problem is: how frequently this kind of problem is expected to occur? If operation at low energy can do that, what´s gonna happen when the real thing starts?
Press release:

Particle accelerators such as the LHC are unique machines, built at the cutting edge of technology. Each is its own prototype, and teething troubles at the start-up phase are therefore always possible.

“The LHC is a very complex instrument, huge in scale and pushing technological limits in many areas,” said Peter Limon, who was responsible for commissioning the world’s first large-scale superconducting accelerator, the Tevatron at Fermilab in the USA. “Events occur from time to time that temporarily stop operations, for shorter or longer periods, especially during the early phases.”
Experience says: stuff happens.

13. Originally Posted by Argos
Problem is: how frequently this kind of problem is expected to occur? If operation at low energy can do that, what´s gonna happen when the real thing starts?
If you have ever been involved in commisioning high complex prototype machinery for research you know these things ALWAYS happen.
Traditionally one of the biggest problems with accelerators was to keep the UHV. Any leak or failure of a small part caused weeks of waiting due to pumping.
Now another time absorbing component has been added. The superconducting magnets which needs a long time to cool down and also to be heated up again in case of failure (und after cooled down again).
It's only that the LHC is a little bit in the spot light now. Normally no one in public would have noticed.
I do not hope it, but I am sure there will some more problems occur before it finally will run.

14. Originally Posted by AndreH
If you have ever been involved in commisioning high complex prototype machinery for research you know these things ALWAYS happen.
I´ve been involved in many things, and I know things happen, especially when it comes to such cutting-edge machines. Take this quote by CERN’s Rudiger Schmidt, coordinator of LHC machine protection:

“It takes 30 minutes to five hours to restart the LHC after a quench,” says Schmidt. “If we quench 10 times a day, it’s too much. If we never quench, we’re being too conservative. We have to operate such that we don’t quench too frequently.”

My concern when asking that question is whether quenching at high energies could be frequent enough. Was that quench expected to happen at this stage? I thought the major concern at this stage was beam collimation.

15. Originally Posted by Argos
I´ve been involved in many things, and I know things happen, especially when it comes to such cutting-edge machines. Take this quote by CERN’s Rudiger Schmidt, coordinator of LHC machine protection:

“It takes 30 minutes to five hours to restart the LHC after a quench,” says Schmidt. “If we quench 10 times a day, it’s too much. If we never quench, we’re being too conservative. We have to operate such that we don’t quench too frequently.”

My concern when asking that question is whether quenching at high energies could be frequent enough. Was that quench expected to happen at this stage? I thought the major concern at this stage was beam collimation.

From the press release 01101001 referred to:

Geneva, 23 September 2008. Investigations at CERN1 following a large helium leak into sector 3-4 of the Large Hadron Collider (LHC) tunnel have indicated that the most likely cause of the incident was a faulty electrical connection between two of the accelerator’s magnets. Before a full understanding of the incident can be established, however, the sector has to be brought to room temperature and the magnets involved opened up for inspection. This will take three to four weeks. Full details of this investigation will be made available once it is complete.
So in yesterdays official press release they are talk about a faulty electrical connection as a cause. So something "trivial" rather than systematic or principle. Of course this could mean they have to open up the system reinspect the connections....... And ofcourse we have to wait the final result.

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so let me get this straight now they are claiming Spring 2009 so that means we are looking at atleast another 5 to 6 months before anything i thought they had said 2 months how did we hit 5-6 now

what did i miss

17. Originally Posted by bmpbmp
so let me get this straight now they are claiming Spring 2009 so that means we are looking at atleast another 5 to 6 months before anything i thought they had said 2 months how did we hit 5-6 now
It will take about 2 months to warm it up, fix the problem, and cool it down again. In about 2 months, they are shutting down for the winter, to save on electricity costs (power's more expensive in the winter), and to allow more work to be done on the equipment (the magnets need to be trained up to full strength, for one). It's either not possible to get it up and running again before the scheduled shutdown, or not worth the expense of doing so for such a short period of operation...and by not doing so, they can spend the cooldown/warmup time that would be required doing more useful work on the accelerator.

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so thats where 5 to 6 months comes from

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More details on the start up fiasco.

Oddly after the BBC discovered the massive quench of about 100 magnets in a log entry on a CERN website, "the entry has since been removed" according to TimesOnline the day after.

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## Hawking radiation does not exist

if you consider the main arguments of CERN for the safety of the LHC, i.e. cosmic rays and Hawking radiation, you only have to google a bit and use Wiki to find out that these arguments are quite weak:

for example: according to Hawking's theory, black holes with a mass < 1000 tons explode. Questions: why are there supposed to be black holes weighing more than 1000 tons, i.e. how did such BHs come into existence at all ? why don't we observe exploding black holes ?

as for the cosmic rays (those high energetic particles relevant): have you ever wondered how they measure them ? Simply put: they hold a piece of plastic towards them, clean the fissure caused by the cosmic ray with Sodium Hydroxide and calculate from the size of the fissure both energy and charge of the particle. Now, that's what I call accurate

just read through corresponding Wiki articles and you'll notice such contradictions and strange ways of supporting Hawking's theories.

If you don't want to read, just watch these:

21. Originally Posted by weather balloon
for example: according to Hawking's theory, black holes with a mass < 1000 tons explode.
According to Hawking's theory, smaller black holes evaporate more quickly. A 999 ton black hole will evaporate more quickly than a 1001 ton black hole, and the evaporation will release quite a bit of energy, but you imply that a black hole below 1000 tons will suddenly explode, which is inaccurate.

Originally Posted by weather balloon
Questions: why are there supposed to be black holes weighing more than 1000 tons, i.e. how did such BHs come into existence at all ? why don't we observe exploding black holes ?
They start out with several times the mass of the sun, and we don't see evaporating black holes because there just hasn't been enough time for them to evaporate.

Originally Posted by weather balloon
as for the cosmic rays (those high energetic particles relevant): have you ever wondered how they measure them ? Simply put: they hold a piece of plastic towards them, clean the fissure caused by the cosmic ray with Sodium Hydroxide and calculate from the size of the fissure both energy and charge of the particle. Now, that's what I call accurate
CR-39 plastic track detectors are just one way of detecting and measuring particle radiation. Cosmic ray observations are not based only on tracks in CR-39, and as for the accuracy of the technique, you've made it quite clear you're not qualified to judge such matters.

I would rather not watch YouTube videos, please summarize them. However, I hope you are aware that YouTube videos are not exactly an accurate source of information.

22. Originally Posted by weather balloon
if you consider the main arguments of CERN [...]
This topic is for news not arguments. (See initial article.)

There are plenty of other topics to argue the goodness of the LHC.

That said... Welcome to BAUT Forum.

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LHC computing grid goes online *

Cool YouTube video at the bottom of the article.

*Link may be slow due to the slashdot effect.

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The inauguration ceremony, which is by invitation only, will consist of speeches, exhibitions and a new audiovisual concert, "ORIGINS", an adaptation of "LIFE: A Journey Through Time", featuring the imagery of National Geographic photographer Frans Lanting and the music of Philip Glass, performed by the Orchestre de la Suisse Romande conducted by Carolyn Kuan. It will be followed by a buffet of molecular gastronomy presented by Chef Ettore Bocchia. The event has been made possible thanks to the generous support of a range of sponsoring companies and organizations, most of which have contributed to the construction of the LHC. It will be followed by a party for the CERN personnel. Full details of the event are available at http://www.cern.ch/lhc2008.

Still waiting for my invitation.

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Originally Posted by Warren Platts

Still waiting for my invitation.
You weren't invited?!
How odd...

26. hmm--volunteer to be one of the monkeys that gets collided, and I bet an invitation is easy to procure!!!

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Whaddya mean? We've all been volunteered to be collider monkeys.

But I understand their point. There's just not enough room at the party for all of us. . . .

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Originally Posted by Warren Platts
Whaddya mean? We've all been volunteered to be collider monkeys.

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CERN Releases Analysis of LHC Incident

Geneva, 16 October 2008. Investigations at CERN1 following a large helium leak into sector 3-4 of the Large Hadron Collider (LHC) tunnel have confirmed that cause of the incident was a faulty electrical connection between two of the accelerator’s magnets. This resulted in mechanical damage and release of helium from the magnet cold mass into the tunnel.
I am so glad I don't have to work on this thing. It's probably going to take the whole winter shutdown to fix it.

Here's a PDF with a little more detail of the incident.
Last edited by Metricyard; 2008-Oct-17 at 01:36 AM. Reason: addition

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Originally Posted by Metricyard
CERN Releases Analysis of LHC Incident

I am so glad I don't have to work on this thing. It's probably going to take the whole winter shutdown to fix it.

Here's a PDF with a little more detail of the incident.
The pdf is quite interesting. Turns out that 6 tonnes of liquid helium was released, rather than the 1 tonne mentioned in your link of Sept. 19th. That's 12,000 liquid gallons that immediately formed a cloud setting off the oxygen depletion sensors.

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