[HN Gopher] Quench of LHC inner triplet magnet causes a small le...
___________________________________________________________________
Quench of LHC inner triplet magnet causes a small leak with major
consequences
Author : untilted
Score : 221 points
Date : 2023-07-21 07:29 UTC (15 hours ago)
(HTM) web link (home.cern)
(TXT) w3m dump (home.cern)
| CrampusDestrus wrote:
| you mean "consequenches"
| ur-whale wrote:
| "Major consequences", and here I was already think a beam of
| protons flying at near the speed of light was let loose towards
| the city of Geneva.
|
| But no, just a section of the accelerator that needs fixing.
| noobermin wrote:
| Bad time to be an LHC grad student.
| enslavedrobot wrote:
| Quenching a magnet is the result of poor planning and poor
| maintenance. The only time I ever hear about magnets quenching is
| at CERN. I remember they quenched ~40 at once when they first
| turned it on, a multi-million dollar error. What the hell are
| they up to over there!?
| aredox wrote:
| I was there when there was a (much bigger) quench during
| commissioning of the LHC [0][1]. It was also at the focusing
| quadrupole modules - maybe the same ones?
|
| I could make a joke about how it's Fermilab's vengeance for not
| having their own accelerator, but that would be dishonest: these
| focusing modules are the most complex ones of the whole ring.
|
| [0]http://stephatcern.blogspot.com/2008/12/photos-of-lhc-
| damage... [1]https://home.cern/news/press-release/cern/cern-
| releases-anal...
| notanote wrote:
| The 2008 quench happened at the other side of the ring. (Sector
| 3-4 then, sector 7-8 now.) The physics run was going very
| smoothly up to now [0]. Last year part of the machine (RF) had
| to be brought to room temperature as well, after a cooling
| tower fault, and there was no beam for four weeks. I get the
| impression that this will take longer, but I hope not by much.
|
| [0]https://atlas.web.cern.ch/Atlas/GROUPS/DATAPREPARATION/Publi
| ...
| fancyfredbot wrote:
| It is amazing that the beam was "dumped" just milliseconds before
| the magnet quenched! If that hadn't happened then the beam could
| have crashed into the magnet and caused a lot more damage.
|
| Dumping the beam means diverting it out of the main LHC ring and
| crashing it into a specially designed buffer (I think it is a
| lump of steel or something). So cool to see this all happening
| automatically.
| tuardoui wrote:
| If like me, you want to see what it looks like :
| https://home.cern/news/news/accelerators/autopsy-lhc-beam-du...
| myself248 wrote:
| So now I'm reading:
|
| https://iopscience.iop.org/article/10.1088/1748-0221/16/11/P.
| ..
|
| And I want microphones, I want to hear the thing ring with
| that 2.3kHz note. I want to feel the 27Hz wiggle and the
| 196Hz thump. I want to get the Slow-Mo guys in there to place
| their camera, and watch the thing jump when a beam hits it.
|
| The amount of energy in that thing just defies intuitive
| understanding from reading a paper, I have to use other
| senses.
| jacquesm wrote:
| The amount of materials science knowledge so casually on
| display is amazing.
| s0rce wrote:
| According to the link below its an 8m long steel tube filled
| with various types of graphite.
| zelos wrote:
| It hadn't occurred to me that there would be significant energy
| contained in a beam of sub-atomic particles. Something like
| 100kg TNT equivalent (~500MJ)? Wow.
| fancyfredbot wrote:
| There's a great article on it here:
|
| https://www.symmetrymagazine.org/article/parking-the-lhc-
| pro...
|
| "Enough stored energy to melt a ton of copper"
|
| "The beam dump is a solid graphite cylinder 8 meters long and
| under a meter in diameter. It's wrapped in a stainless-steel
| case, filled with nitrogen gas, and surrounded by iron and
| concrete shielding."
| nvusuvu wrote:
| Does the beam dumps make the meterial they were dumped into
| radioactive? What is that process like?
| mrguyorama wrote:
| As discussed in one of the decommissioning articles
| someone else posted, it does make the beam dumb
| radioactive! I hadn't thought about it but it makes sense
| with how much energy you are pumping into not that many
| atoms in the end, and when you do that, you tend to get
| radioactive atoms.
| Sharlin wrote:
| Not just any energy but ultrarelativistic protons! That's
| going to result in all sorts of interesting daughter
| nuclei when they slam into the atoms in the buffer.
| pfdietz wrote:
| The protons that are hitting the dump are at energy far
| beyond the binding energy of a nucleus. When they hit
| nuclei there, they shatter them. A shower of
| progressively less energetic particles forms, including
| large numbers of newly freed neutrons.
|
| There are accelerator-driven fission reactor ideas that
| would use ~1 GeV protons (much less energetic than the
| protons here) to produce neutrons to drive a subcritical
| target. These might be useful to destroy certain nuclear
| waste isotopes.
| testtestabcdef wrote:
| That's crazy. I never would've thought that either. These
| small facts which you can barely read in "mainstream media"
| are what makes the LHC absolutely fascinating and impressive.
|
| I was always like "Yeah that's just a small beam and the
| magnets are to navigate it in circles". In retrospect it does
| make sense now why people were concerned about the collision
| of such beams.
| Ekaros wrote:
| Also, when you really think about it. Why would you need 27
| kilometre long circle if you weren't dealing with some
| absolutely massive amounts of energy. Couldn't you do it
| with lot less?
| Sharlin wrote:
| Indeed. It's all about the curvature. Even with all those
| incredibly fancy superconducting magnets you just can't
| force protons this fast onto a circular path any smaller
| than this when they very much would like to go straight.
| rcxdude wrote:
| Yeah, it has the energy of a semi truck going at a few
| hundred mph but in something that is about 1nanogram of mass
| (about that of the average human cell).
| londons_explore wrote:
| How much of the energy is in the moving electrons/protons,
| and how much energy is stored in the superconducting
| magnetic fields?
| datenwolf wrote:
| All of it in the relativistic kinetic energy of the beam.
| The energy in the superconductor magnets is a whole
| chapter of its own; their energy dissipating into heat is
| what makes the Helium boil off during a quench.
|
| Also static magnetic fields don't "do" work, by that I
| mean, that you can not extract energy from a magnetic
| field by sending particles through it: The Lorentz force
| is perpendicular to both the movement of the particle
| through the field, and perpendicular to the field itself.
| Hence taking the inner=scalar=dot product of the force
| vectors and trajectories they come out as 0, i.e. no work
| is done.
|
| You need dynamic magnetic fields to do work.
| zipotm wrote:
| [flagged]
| SiempreViernes wrote:
| Man, so relieved it's just cooling one section that is meant by
| "major consequences", title made me think of the explosion during
| commissioning. Looks like it's only sector S78 that needs
| attention: https://op-
| webtools.web.cern.ch/vistar/vistars.php?usr=LHC2
|
| This report is impressively detailed for being put out just two
| days of the incident, but I guess LHC having world class
| technical diagnostics teams is not too surprising.
| bayindirh wrote:
| When I was visiting CERN, the whole accelerator was in
| maintenance mode. We have seen a detector (IIRC it was ATLAS)
| which was disassembled in layers, so we were able to see almost
| all of it.
|
| Our guide explained that whole schedule for maintenance and
| operation is set in stone and whole schedule is planned almost
| to hour resolution for the next six months or so. Also it's
| worth noting that, there is periodic maintenance that needs to
| be done, and that's also planned in advance.
|
| Because of this stringent requirements, "several weeks" of
| shift is indeed a major problem, and by several I guess they
| are looking to ~8 weeks, if not more.
| FireBeyond wrote:
| My uncle, who is not a physicist, but "one smart mf", was one
| of the heads of the beam instrumentation team at Fermilab,
| and spent a large part of his career designing, building and
| maintaining detectors. It utterly blows my mind.
| vasco wrote:
| The "major consequences" seem to be for the schedule:
|
| > This incident will probably have a great impact on the LHC
| schedule, with machine operation unlikely to resume for at
| least several weeks.
|
| I also read it instantly in case they had a black hole on their
| hands, even though I'd expect us all to be dead almost
| instantly if any real "major consequence" event truly happened
| in the accelerators.
| dukwon wrote:
| "at least several weeks" is technically correct but I think a
| bit of an understatement. A sector takes about 3-4 weeks to
| warm up and 4-5 weeks to cool down. _Then_ it needs to
| undergo powering tests and probably some "training"
| quenches.
|
| Since the winter shutdown is scheduled for end of October
| (thanks to the energy crisis), there's a good chance we are
| finished with proton collisions for the year. If the leak can
| get fixed and the sector cooled down by mid/late September,
| we might have time for the heavy ion run. Last year's ion run
| was cancelled due to shortening the year, so 2 years in a row
| would not be great.
| foobarian wrote:
| Is there any plan to migrate to higher temperature
| superconductors which might not require such low
| temperatures?
| scarmig wrote:
| They introduce their own problems. They're typically
| brittle ceramics, making them hard to work with. They're
| more expensive to manufacture. And they have a lower
| critical current density (i.e. there's less current they
| can carry before losing superconductivity).
| krisoft wrote:
| > I also read it instantly in case they had a black hole on
| their hands, even though I'd expect us all to be dead almost
| instantly if any real "major consequence" event truly
| happened in the accelerators.
|
| Idk why people think this. Black holes are not magic. They
| have exactly as much gravity as the mass had which collapsed
| into them.
|
| As you go about your life right now the gravity of
| Switzerland is pulling you towards it a tiny bit. If due to
| some crazy event the mass of the whole country would collapse
| into a black hole that black hole would still tug you the
| same way and the same amount.
| ericd wrote:
| I'm not a physicist, but it seems like they're a little
| magic, in that they're so far from our normal experience,
| since gravity is proportional to the inverse square of the
| distance, and the distance to their center of mass is
| relatively very small, so you can get an extremely strong
| pull relative to a normal object of the same mass. It seems
| like even a very small black hole falling onto things could
| snowball, unless there's something that counters that? Do
| black holes lose material/get less dense/evaporate under
| certain conditions?
| marcosdumay wrote:
| > Do black holes lose material/get less dense/evaporate
| under certain conditions?
|
| They radiate something similar to heat (with wild
| possibilities for temperature).
| jamesmaniscalco wrote:
| Yes, black holes are theorized to evaporate due to
| Hawking radiation [0].
|
| [0] https://en.wikipedia.org/wiki/Hawking_radiation
| bauruine wrote:
| >I'd expect us all to be dead almost instantly
|
| Not an expert at all but from what I've read you'd expect
| wrong. Even if they could create a black hole out of the
| Matterhorn it would be so small, less than a hydrogen atom,
| that it doesn't interact much with anything.
|
| "Even though a microscopic black hole might contain the mass
| of a mountain, it would experience almost no friction as it
| passed through regular matter. It would fall through regular
| material as if it wasn't there." [0]
|
| So the worst thing would be the missing Matterhorn which
| pretty sure would upset the Swiss.
|
| [0]: https://www.universetoday.com/1930/are-microscopic-
| black-hol...
| xp84 wrote:
| So... would it fall to the center of the Earth? At that
| point could it start consuming matter? I have to admit I'm
| very ignorant of how a small black hole could grow (or
| not).
|
| Not saying I believe the LHC can make those or anything,
| just intrigued by the questions.
| marcosdumay wrote:
| If they manage to create one with almost no velocity, it
| would keep falling through the Earth, down, up and down
| again, for either something between atoseconds or
| centuries, until it either explodes or hits enough matter
| to get big enough to matter.
|
| Or, more realistically (as realistic as we can be talking
| about the LHC creating black holes, AKA, not realistic at
| all), it will be launched into space in some random
| direction.
| ianai wrote:
| It's so small at that point it begins to act a little
| like a white hole (Hawking radiation iirc?) and
| evaporates quickly. It's surprisingly difficult for
| matter to cross an event horizon.
|
| Edit-actually having a small black hole would unlock some
| truly sci-fi sounding tech. Like the fastest interstellar
| travel, seemingly unlimited power, etc.
| scarmig wrote:
| You're leaving out evaporation. A black hole with the mass
| of a mountain would evaporate on the order of a second.
|
| That would also release energy the equivalent of ~20M
| megatons of TNT, which is half a million times that of Tsar
| Bomba and around that of the KT event. The Swiss wouldn't
| be too upset about anything.
| nonameiguess wrote:
| There was some hope at one point that something like the LHC
| might produce black holes, but not the type you're thinking
| of as massive gravity wells that form when stars collapse. It
| has been postulated that the early universe in the immediate
| aftermath of the Big Bang may have contained primordial black
| holes, and any that were large enough to still exist today
| might be a possible source of dark matter. Any formed in a
| particle collider would be particle mass, not star mass, and
| have the gravitational attraction of particles, and evaporate
| almost instantly due to Hawking radiation. They'd have been
| harmless, but if it had been possible, it would at least
| confirm they actually can exist and observing the decay would
| have been our only realistic hope of observing Hawking
| radiation likely at least in this century.
| dark-star wrote:
| They would have written "Unforeseen Consequences" in that
| case ;-)
|
| (https://developer.valvesoftware.com/wiki/Unforeseen_Conseque
| ...)
| speed_spread wrote:
| A black hole is not unforseen, they don't call the place
| Black Mesa for nothing. But a resonant cascade, on the
| other hand...
| 3cats-in-a-coat wrote:
| You can't create a black hole in LHC. Although sometimes when
| I read social media I wish they could.
| cubefox wrote:
| Even if the tenth digit of pi _can 't_ be a six, it still
| _might_ be a six, namely when you don 't know it can't be a
| six because it is a three. Uncertainty is different from
| possibility.
| 3cats-in-a-coat wrote:
| This is just my personal opinion, but the mechanism that
| creates particles and black holes is the same. Meaning
| without throwing incredible mass at it, you won't make a
| black hole. You can't. You'll make a particle or break
| apart one. Which is in fact what happens. There are also
| many natural events that resemble what the LHC does, at
| even greater energies and much greater mass, and yet no
| black holes. A black hole is dangerous because it's a
| planet worth of mass in compact singularity. If it has no
| such mass it can't do anything.
| jfengel wrote:
| Putting this on a slightly stronger footing:
|
| Black holes don't have to be enormous. We focus on the
| enormous ones because we know how they form from stars,
| but there's nothing inherent in black hole math to
| prevent tiny ones.
|
| You can, in theory, create ones from energy, because mass
| and energy are the same. It's not impossible to create a
| tiny black hole in a collider.
|
| Just not the LHC. It doesn't have anywhere near enough
| energy, even for the tiniest black hole. And even if
| there were some unexpected physics that did let a
| microscopic black hole form, it would instantly vaporize
| in a burst of Hawking radiation. (The smaller a black
| hole is, the faster it evaporates.)
|
| If somehow _all_ of that were wrong, and the LHC did
| create a tiny black hole with a lifetime longer than a
| yoctosecond, it could grow and become a real problem very
| quickly. But if you 're inventing that much physics, you
| might as well just worry about the appearance of a mega-
| space-goat that eats the Earth, because it's equivalent
| levels of guessing.
| cubefox wrote:
| I found a more detailed analysis here:
|
| https://youtube.com/watch?v=Dp2C4J2yMe4
|
| Apparently the probability is indeed very low.
| tux3 wrote:
| Vistar is so cool :)
|
| Also, here's a public grafana I just found with temperature
| charts in S78 and a bunch of other cryo data:
| https://dash.web.cern.ch/d/iDRuWWHGz/sector-78-trend
|
| Not that I can do anything very interesting with that
| particular bit of information, but I'm always happy to see open
| data. We could really use more of that in public science, and
| CERN is really doing a great job
| lhoff wrote:
| Partially related recommendation for the german-speaking crowd
| here:
|
| The Raumzeit podcast released the second episode of a longer
| series about the cern. In the frist one he discussed the history
| and success of the cern with the leader of the experimental
| physics department and in the second one he talks to the guy who
| is in charge of operations of the proton synchrotron about the
| actual accelerators.
|
| https://raumzeit-podcast.de/2023/07/05/rz111-cern-geschichte...
|
| https://raumzeit-podcast.de/2023/07/19/rz112-cern-die-beschl...
| ggm wrote:
| The inner tube is hard vacuum? Does freeze over risk rupture and
| also incur re evacuation and time to get those last pesky digits
| of nothing?
| trenchgun wrote:
| Tiny black holes that are going to swallow the earth in the
| coming hours?
| testing_123 wrote:
| [flagged]
| codeulike wrote:
| Quench
|
| Nice verb
| fifteen1506 wrote:
| For major click-bait for Half-Life 1 players, I propose the title
| to be prefixed with "UNFORESEEN CONSEQUENCES: ".
| misterflibble wrote:
| Gordon! Get away from the beam!!!!
| ComodoHacker wrote:
| This report really has disturbingly strong Half-Life 1 vibes
| for me.
| Aardwolf wrote:
| The major consequence here is a few weeks of repair time,
| there wouldn't be much gameplay in Half-Life 1 if that were
| it :)
| FeepingCreature wrote:
| "It's not... it's not shutting down! Aah-- oh wait, it shut
| down. All good."
| Gordonjcp wrote:
| [dead]
| dr_faustus wrote:
| Just reading that gives you an inkling of an idea what kind of
| amazing feat of engineering the LHC is. I really hope governments
| keep funding basic research like that because it teaches us not
| only about nature but also how to built those incredible
| machines.
| sakex wrote:
| Do we know if this could have an impact on the local population?
| Also is there any research on the effect of the LHC on people
| living in Geneva and around?
| cominous wrote:
| Read the article. It was a >local< event at one of the magnets
| which caused the whole magnet to freeze over. The
| "consequences" are, that the whole accelerator needs to halt
| operations to repair the element. That takes quite a while and
| will postpone the schedule..
| sakex wrote:
| Sure but is it impossible that something would leak when
| injecting massive amounts of energy in a gigantic tunnel?
| flangola7 wrote:
| Besides helium, what substances are you worried about
| leaking?
| constantcrying wrote:
| But _what_ would leak? The helium? The nitrogen?
|
| The only real danger is if you are in an enclosed space and
| oxygen is displaced. Nitrogen gas is about the least toxic
| substance imaginable and helium will literally just go away
| unless you make absolutely sure to trap it.
| __alexs wrote:
| > Nitrogen gas is about the least toxic substance
| imaginable
|
| Interestingly basically all gasses appear to be bad for
| you in some way. Perhaps the vacuum of space truly is
| where we belong? /s
|
| https://en.wikipedia.org/wiki/Nitrogen_narcosis
|
| I can't find the study right now but I think this affect
| is even measurable at atmospheric pressure in that if you
| give replace the Nitrogen with other noble gasses you can
| observe improvements in cognitive function.
| constantcrying wrote:
| 100% of substances are bad for you under some
| circumstances.
|
| You have breathed in millions of liters of nitrogen. It
| is as safe as any substance could possibly be.
| MikeDelta wrote:
| The amounts of energy injected are not that large. 1TeV,
| the order of magnitude, is (according to google) the motion
| energy of a flying mosquito. You don't even feel that
| landing on your body.
|
| The special part is that this energy is put into one
| particle, which makes it able to achieve other
| interactions.
|
| Such particles sound scary, but the only special thing
| about this is that we, humans, have produced that. Our
| earth is bombarded constantly by cosmic high-energy
| particles of much much higher energy [0]. I am talking
| about extra-galactic particles with energy levels unknown
| to earth.
|
| [0]
| https://masterclass.icecube.wisc.edu/en/analyses/cosmic-
| ray-...
| defrost wrote:
| _You only love your collider_
|
| https://www.youtube.com/watch?v=1e1eLe1ihT0
| phatskat wrote:
| Thank you? Yes, thank you. I think.
| imdsm wrote:
| Do we know if... the magnet heating up, and the helium leaking
| into the vacuum chamber... could have an impact on the local
| population? I think they'll be ok!
| contravariant wrote:
| I mean worst that could happen is that it's harmful to
| someone standing right next to it if it fails
| catastrophically (no clue if that's even a realistic concern
| in this case). But since this happens over 50 meters below
| ground I'm not too worried.
|
| Not that it was put that far below ground for safety reasons,
| it was mostly to save on the amount of land required and to
| shield the detectors from pesky background radiation (not the
| other way around).
| cesarb wrote:
| > I mean worst that could happen is that it's harmful to
| someone standing right next to it if it fails
| catastrophically (no clue if that's even a realistic
| concern in this case).
|
| AFAIK, these areas are restricted while the LHC is
| operating, so there would be nobody near it (and I believe
| trying to enter these areas triggers an interlock which
| stops the whole system before you can get near it).
| gostsamo wrote:
| Noble gases are not chemically active, but some
| interdementional rifts might allow access of alternative life
| forms to our reality.
| rob74 wrote:
| I think you're mixing things up - the incident you are
| referring to happened at the Black Mesa Research Facility,
| not at the LHC...
| gostsamo wrote:
| The LHC was a cover. Do you really think that governments
| honestly will spend billions for fundamental science
| without a back motive? It is the ideal environment to hide
| a secret base where they can divert money, energy, and
| people to.
| Aardwolf wrote:
| Unbelievable the LHC is already running for 15 years! When it
| was just finished it was still the heyday of funny flash
| animations on the internet, some of course joking about the LHC
| ending the world:
|
| https://www.newgrounds.com/portal/view/469806
| sakex wrote:
| Yes I think it's great, but still it would be good to have
| research to understand the effect on local population.
|
| It is intellectually dishonest to just say it is not possible
| for anything to leak and have adverse effects on people
| without actively researching the matter.
| MikeDelta wrote:
| Don't you think the Swiss and French governments wouldn't
| have thought about safety almost 70 years ago?
|
| Safety is an important part of the collaboration, which is
| evident when you work there.
|
| This is evaluated by people who understand physics,
| chemistry, and biology, and it is the alternative science
| people that tend to not want to believe that and keep
| warning of dangers that don't exist.
|
| It is good to always remain critical, but after a while
| you've used up all arguments to explain that the radiation
| in your microwave is not radioactive.
|
| I guess the scary part is that they called it a leak
| instead of a hole. I am sure if I say there is a leak in my
| sock that some will start to worry.
| throwawaylinux wrote:
| > Don't you think the Swiss and French governments
| wouldn't have thought about safety almost 70 years ago?
|
| This isn't an argument. 70 years ago France was
| conducting atmospheric nuclear tests that caused people
| and inhabited land to be exposed radioactive fallout.
| [deleted]
| contravariant wrote:
| You should really do some more extensive research about the
| possible harmful effects of your comments more carefully
| before posting.
|
| This one is giving me a headache.
| DoctorOetker wrote:
| As the article says, quenches sometimes happen.
|
| Effects on the local population? You mean those who work
| there underground? Their voice may change pitch a little,
| but its only a temporary effect.
|
| Helium is present in our atmosphere. And presumably on your
| birthday party when a balloon was popped.
|
| Effects on the wider population?
|
| A couple of delays and reorganizations at the surrounding
| hotels and restaurants.
|
| Basically: the telephone will ring.
| bradrn wrote:
| The was a small leak of helium within the instrument. Such
| incidents are completely unexceptional with superconducting
| magnets, and pose no risk to anyone outside the room where
| it happen, since both helium and nitrogen are about as
| inert as gases can get. I suspect it wouldn't even have
| made the news if it hadn't delayed the experiments.
| fabian2k wrote:
| We know what helium and nitrogen gas do and what dangers
| they represent. We also know how much of them are in the
| LHC. The main danger is that both displace oxygen, so you
| can suffocate e.g. if a large amount of helium is released
| by a quench in a small room. But this isn't any danger to
| the surrounding area, there just isn't enough liquid helium
| or nitrogen in there.
|
| Both gases are inert, so they really don't do anything
| else. There isn't anything to investigate here.
| db48x wrote:
| It's just helium. Have you ever bought a helium balloon,
| the kind that float? This is the same stuff that's in the
| balloon. It's also used as a mixture gas by deep-sea
| divers. It's chemically completely inert; breathing it in
| doesn't have any particular effect on the body. It's
| harmless, unless you fill an entire room with it so that
| all the oxygen is displaced.
|
| Are people really so scientifically illiterate that they
| immediately assume that if anything goes wrong with a
| complicated machine that it will be harmful to their
| health?
| gus_massa wrote:
| My guess is that people imagine that the high energy
| particle beam transforms the helium and nitrogen used to
| cool the magnets in radioactive gases that may be
| dangerous.
|
| But the beam never colides with the gas deposits. The
| helium and nitrogen are used to cool the magnets that are
| used to bend the beam that travels inside a vacuum tube.
|
| [And even if the beam colides with the gas deposits, I
| don't expect too much radioactive waste. Each particle in
| the beam has a lot of energy, but there are very few.
| This links https://public-
| archive.web.cern.ch/en/lhc/Facts-en.html says "trillions"
| ( 10^12 ?) of protons, but a glass of water has like
| 10^26 protons. A nuclear power plant has much more
| radioactive material and during normal operation produce
| much more collisions that can turn container
| radioactive.]
| zamalek wrote:
| You never know, it might have been one of those time-
| travelling tachyons coming back to prevent its own creation
| (an actual conspiracy theory during the initial problems at
| LHC).
|
| For anyone genuinely concerned about LHC, we've detected
| cosmic rays hitting our atmosphere at orders of magnitude
| more energy than what LHC is doing.
| https://en.wikipedia.org/wiki/Oh-My-God_particle
| throttlebody wrote:
| How does that bode for space travel and being on the moon.
| That's a lot of energy
| zamalek wrote:
| A few inches of water or regolith would probably be
| enough for shielding.
| Filligree wrote:
| Not sure how seriously anyone ever took it, but-
|
| https://www.lesswrong.com/posts/C2uvzYeoMkwMmscMx/hamster-
| in...
| pif wrote:
| What do you propose exactly? What should we monitor?
|
| By the way, I worked at CERN for a few years up to the first
| months of operations of LHC. Furthermore, I've been living in
| the region since then; for several years, my home was exactly
| over the LHC tunnel.
|
| I've never got a nightmare from that!
| SoftTalker wrote:
| Not sure, but the engineers all came running out of the room
| talking like Mickey Mouse.
| jjgreen wrote:
| I think they'll be OK:
| https://www.hasthelargehadroncolliderdestroyedtheworldyet.co...
| fabian2k wrote:
| > During such a quench, the liquid helium in the magnet warms
| up and turns into a gas that is recovered by the cryogenic
| system to be re-liquified, ready to cool down the magnets
| again.
|
| They're capturing the helium, so it isn't released usually. Not
| sure what they do with the nitrogen, I'd guess that is released
| as it is much cheaper. But in any case the amounts involved in
| such a quench are only a danger in the immediate vicinity, not
| outside. So if you're in the same room as a quenching magnet
| and the room isn't sufficiently sized or ventilated, there
| could be danger. But that's about the limit to it.
| Ekaros wrote:
| Took a tour in local university physics lab dealing with
| helium. My takeaway is that liquid nitrogen is essentially
| free. And used to protect or keep helium parts colder. So
| anyway in process you have so much of it that simply having
| it boil away or be discarded is not big deal.
| SoftTalker wrote:
| It's comparatively free; the air is nearly 80% nitrogen.
| The equipment to produce liquid nitrogen has a cost and
| uses a fair amount of electricity. Labs that use a lot of
| liquid nitrogen may produce their own, but often it's
| produced industrially in large quantities and trucked to
| customer sites.
|
| It has a lot of uses, from dermatology to machine shops.
| gus_massa wrote:
| A few years ago, while doing a physics lab for students in
| the university, we needed ice and liquid nitrogen. It was
| weird that is was easier to get some liquid nitrogen[1]
| than ice cubes[2]. IIRC we asked for the official price of
| liquid nitrogen, and it was similar to the price of soft
| drink like coke.
|
| [1] Because it was used regularly in a few of the research
| labs. Just get a dewar flask that is not made of glass, and
| ask nicely.
|
| [2] No refrigerator in the lab, the cafeteria didn't have
| any, most refrigerators had no ice cubes or a huge ice
| block where there use to be the ice cubes shelf.
| meindnoch wrote:
| Severe mutations and deformities.
| DoctorOetker wrote:
| Brain damage for the schedule programmer.
| SiempreViernes wrote:
| Uh, I guess some of the locals will get second-hand bummed-
| outedness from their acquaintances at CERN?
|
| Did you even click on the link dude? The picture showing frost
| on the outside of a metal tube in a sealed tunnel ~100 m under
| ground is the _total_ extent of the exterior effects...
| harperlee wrote:
| It is a small leak of helium that disables a refrigeration
| unit.
| Animats wrote:
| Not too bad. The 2008 magnet failure took two years to repair,
| with over 50 magnets affected.
| unixhero wrote:
| Unforeseen consequences
|
| Don't forget your crowbar
| formerly_proven wrote:
| This is a very nicely written, clear article. This is what good
| science communication looks like.
| ThePhysicist wrote:
| Helium leaks are a nightmare. During my PhD I worked with a self-
| built dilution cryostat that would often have leaks in the
| custom-built Indium seals. To find the leaks you'd have to pump
| the cryostat to high vacuum, hook up a portable mass spectrometer
| tuned to Helium to the pump circuit and then spray different
| parts of the cryostat with Helium from a regular gas canister.
| The He would then get sucked in through the leak and show up on
| the mass spectrometer, which was coupled to a loudspeaker so it
| would cause a sound whose pitch increased with the measured He
| density. Once you found the leak you had to vent the entire
| system, remove the faulty seal and replace it with a new one. All
| seals were handmade, i.e. you took a small filament of Indium,
| placed it between the flange and the housing (after carefully
| cleaning everything with Acetone) and carefully screwed it shut,
| turning each screw only a tiny bit at each turn and going around
| all the screws until you could see the Indium squeeze out of the
| edges.
|
| Even worse, some leaks would only show up when the system got
| cooled down to liquid Helium temperature. When that happened you
| were out of luck as you can't cool the system down to 4K before
| spraying it with Helium, so you had to just guess where the leak
| might be and replace all seals in that area until you found the
| right one. Going even deeper in temperature would eventually turn
| the He4 suprafluid, which means that it loses all internal
| friction. In that state it would squeeze through even the tiniest
| molecular cracks, so again if that happened you just had to redo
| all the seals and hope they would hold.
| COGlory wrote:
| This sounds miserable!
| londons_explore wrote:
| One would imagine there must be some kind of paint you can
| paint onto the outside of a vacuum flask, and have it be sucked
| into any gaps and solidify there.
|
| It seems they already make a product for that - vacuum grease.
| It can get sucked into even a fairly large crack, and plug it
| up, as long as the depth of the crack is much longer than the
| width, then atmospheric pressure won't provide enough force to
| send it deeper into the crack.
|
| And the grease itself is designed not to evaporate into the
| vacuum.
|
| Whats wrong with using that?
| s0rce wrote:
| There are some products but in systems with metal seals you
| don't use grease/sealant as as they off-gas various
| contaminating small molecules
|
| https://www.tedpella.com/vacuum_html/High_Vacuum_Leak_Sealan.
| ..
| [deleted]
| isoprophlex wrote:
| For a schlenk line in chemistry where you need 0.1 - 1 mbar,
| sure! But this is insane physics territory... Like other
| people said, grease isn't behaving like you think it would at
| millikelvin temperatures, or at pressures lower than those in
| the interstellar medium.
|
| If you have a big aluminum chamber under ultra low pressure,
| guess what you're concentrating in there? Hydrogen and helium
| from the atmosphere that's seeping through your metal. Crazy
| stuff that's (sadly) not fixed by slapping PTFE paste or
| vacuum grease onto it.
| ISL wrote:
| Those materials exist (see Apiezon vacuum grease and Lesker
| vacuum sealant). In less-demanding or desperate applications,
| they can work.
|
| But like similar last-ditch repairs (think automobile muffler
| tape or radiator sealant), they only occasionally last.
| Usually the best thing to do is to go actually fix the
| problem.
|
| The above advice assumes you're trying to maintain high
| vacuum (10^-5 torr or lower pressure). At low vacuum (10^-3
| torr and above), that trickery can work wonders.
| ThePhysicist wrote:
| Not sure if there's vacuum grease that can work at very low
| temperatures, the upper stage of the cryostat would go to 300
| mK and the lower stage to 20 mK, at that temperature non-
| metallic compounds tend to get porous. There are materials
| that can work in there but to my knowledge nothing that was
| an easy solution, at least at the time.
| lazide wrote:
| If you're dealing with single molecule cracks and extreme
| vacuum, even vacuum grease is going to offgas and
| contaminate things.
|
| Hydrogen is EXTREMELY small, the temps the poster is
| talking about are very very low, and XHV/UHV is extremely
| low pressure vacuum.
|
| Like 'single molecules we don't want rattling around is a
| problem', 'more vacuum than outer space vacuum', and
| 'oxygen long ago turned into a solid' temperatures.
|
| [https://en.wikipedia.org/wiki/Vacuum_grease]
| remus wrote:
| Just speculating, but helium molecules are pretty small, so
| will be able to leak through tiny gaps where the paint/grease
| would not penetrate.
| beowulfey wrote:
| Cryogenic temperatures maybe?
| hwillis wrote:
| > paint onto the outside of a vacuum flask, and have it be
| sucked into any gaps and solidify there.
|
| Stuff like paint will tend to be very permeable- if it relies
| on a solvent drying out, then obviously its permeable enough
| to let the solvent through. Even if it does dry to a very
| solid state, there will be a very very long tail of
| evaporation of volatiles inside the substance.
|
| > It seems they already make a product for that - vacuum
| grease.
|
| Vacuum grease isn't perfect- it's not recommended for the
| high end of high vacuum or for UHV. Or for single digits of
| kelvin.
|
| Another big factor is that if you're doing science, you
| probably want to go out of your way to eliminate
| contamination like that. Guessing about the possible chemical
| interactions of a secret proprietary substance under
| extremely low temperature and pressure is not a fun way to
| get your doctorate.
| ripperoni wrote:
| Yes, a huge factor is the outgassing of materials. While
| just solidifying and a long time after that, it gases off
| solvents and other small particles that you constantly have
| to pump away and that raise your pressure noticeably.
|
| In cryogenic environments this is less of an issue because
| things are more sticky, but in a room temperature apparatus
| targeting ultra high vacuum this is troublesome or
| impossible.
| jerf wrote:
| AlphaPheonix on YouTube has an excellent and informative video
| of a very similar process of testing seals, though the vacuum
| is pulled for a different reason:
| https://www.youtube.com/watch?v=VD69crOFx10
| simonjgreen wrote:
| That's sounds horrific. It makes me wonder what proportion of
| time you'd spend massaging and debugging your lab equipment vs.
| actually using it?
| ThePhysicist wrote:
| Basically 2-3 years of getting everything to work and testing
| each component, than 2-4 weeks of good measurements that
| comprise the main results of the PhD thesis.
| gaze wrote:
| For an experimental physicist you basically debug until you
| get the data for your paper or until you find your sample is
| bad. So you're debugging 99% of the time.
|
| In many fields it's rare to build new instrumentation. You
| fab with well known techniques with one subtle modification,
| so it's not even clear what part of your time isn't spent
| debugging.
| causality0 wrote:
| It's like a high-end fighter jet. An F-22 needs 43 man-hours
| of maintenance per flight hour.
| gus_massa wrote:
| And that does not include the problems with electric wires.
| We had an unofficial rule: after half an hour debugging the
| electric wires just change all of them. I still have
| nightmares about BNC connectors.
| gaze wrote:
| That's a pretty terrible rule. Unless you're rolling over
| them with chair wheels, a bad BNC cable should be easy to
| spot by visual inspection. In my 20 years of
| instrumentation work it's rarely the cable.
| gus_massa wrote:
| It was a students' lab, where each device is connected
| and disconnected 2 or 3 times per day, 5 days per week.
| The wires get a lot of use and abuse.
|
| Usually the problem is the tip that got slightly loose
| and the signal is now intermittent or null. IIRC, when we
| detected the wrong wire we had to put it in a box and the
| guy in charge of the lab equipment would fix it later.
| dekhn wrote:
| To that rule, my team added another: when throwing away the
| cable, cut it in half. So nobody scrounges a cable out of
| the garbage can only to waste more time debugging a bad
| cable.
| NotYourLawyer wrote:
| If you've got an apparatus with 20 parts (a low estimate) and
| they're all independently 95% reliable (a high estimate),
| it's only gonna be in a usable state 36% of the time.
| javajosh wrote:
| I think I'll bookmark this comment and come back to it the next
| time I feel annoyed by tracking down a software bug.
| throwaway290 wrote:
| Based on you description... Couldn't you just go so cold He
| goes superfluid so you find all the leaks right up?
| dreamcompiler wrote:
| Not my area, but I know He is very expensive (as is getting
| it cold enough to make He4) so using He4 as a leak detector
| is likely going to blow the entire experiment's budget.
| YakBizzarro wrote:
| Oh yes, way too familiar situation... dry cryostats were really
| a game changer. Apart of the incredible advantage of not having
| to refill them frequently and on Sunday, they are much more
| reliable and without any cold seal
| user3939382 wrote:
| This is a more extreme description of why I hate plumbing.
| arbuge wrote:
| ...and central air conditioning.
|
| 2 evaporator coil leaks in my 5 year old house already,
| another one currently suspected.
| DANmode wrote:
| Why oh why doesn't everything use radiant by now?
| allenrb wrote:
| Seriously. It is annoying when some ancient pipe in my
| radiator plumbing decides to leak. This sounds orders of
| magnitude worse.
|
| The things we humans put up with to try and understand the
| universe!
| nazgulsenpai wrote:
| As someone who is currently in a game of cat and mouse with
| an intermittent drip from underneath the kitchen sink, this
| was exactly the first thing that came to my mind also!
| lotsofpulp wrote:
| I feel like I would just replace all of it than play cat
| and mouse. Surely it would be cheaper in time, and low cost
| until you figure out you have to replace the whole sink.
| civilitty wrote:
| Graduate and postdoc labor is cheap, pressure vessels are
| not.
| [deleted]
| xp84 wrote:
| Which is kinda funny since plumber labor is expensive,
| and new pipes under the sink are cheap.
| civilitty wrote:
| The plumbers made better life choices :-)
|
| The grad students and postdocs are sacrificed... for
| science!
| nazgulsenpai wrote:
| I have replaced the p-trap under sink already, but your
| comment actually got me thinking maybe it's a leak around
| the caulk seal where the sink joins the counter or
| faucets!
| Arrath wrote:
| No plumbing adventure is complete without 6 trips to your
| local hardware store, thinking each one is surely the
| last.
| johncalvinyoung wrote:
| My family (avid do-it-yourselfers, who renovated each
| house we lived in) used to score project size by trips to
| the hardware store, both proposed/planned/expected, and
| also actual. :P
| gus_massa wrote:
| Even a new vessel need new plumbing to connect it to the
| vacuum pump (or pumps, sometimes you need one to to go
| from ambient pressure to low pressure and another to go
| from low pressure to very low pressure) and the pressure
| measuring device(s) and also sealing the holes where the
| wires go (I guess they have some sensor inside the vessel
| connected to things that are outside). So a brand new
| vessel means restarting all the seals from zero.
| finnh wrote:
| i believe the comment you are responding was talking
| about actual home sink in GP comment, not the LHC =)
| toast0 wrote:
| I had a bathroom sink where we put in a new faucet that had
| a pinhole leak in the tubing which you couldn't see when
| installed. Everything would look good, but the water would
| come out and drip down the drain pipe.
| peterleiser wrote:
| I recently played this same cat and mouse game with no
| success, so I built a better mouse trap using a disposable
| aluminum foil cooking pan and a Moen water leak sensor. I
| put the drip pan on a steep angle and bent/reshaped it to
| collect water at a single point where I placed the sensor.
| I wrapped the sensor in a small piece of paper towel so
| that even a single drop of water would be absorbed by the
| paper towel and trigger the sensor. I tested it with a
| single drop of water from a syringe, replaced the paper
| towel to reset the trap, and eventually I got a
| notification in real time on my phone as it dripped. Over
| kill? Yes. But it lead to me finally finding the issue.
| pjc50 wrote:
| Nuclear reactors offer all the fun of leak tracing and
| invisible cracks with the added bonus that the fluids
| involved are extremely radioactive and contaminate everything
| they touch. This is why all the "just mass produce small
| reactors" and "just try thorium / molten salt" stuff hasn't
| taken off, and may never: all the beautiful theory
| disintegrates into man-years of laborious leak testing.
| PaulHoule wrote:
| LWR coolant is not that bad. They keep the water very clean
| with ion exchange resins because otherwise you can have
| problems with corrosion. Workers sometimes float in the
| water during refueling where they flood the area about the
| reactor and spent fuel pond and open the lid of the reactor
| vessel.
|
| Leaks in liquid metal fast reactors are much more obnoxious
| but still manageable. Sodium catching on fire when it hits
| air frequently isn't as bad as it sounds (a "pool fire"
| isn't particularly hot or dangerous but a "spray fire" can
| be) but it is important to catch sodium leaks quickly
| without false alarms and many development projects had
| trouble with that.
| yborg wrote:
| https://en.wikipedia.org/wiki/Monju_Nuclear_Power_Plant
|
| I always enjoy the handwaving by nuclear enthusiasts.
| These are some of the most difficult engineering systems
| routinely built and operated by mankind, where a coolant
| loss accident doesn't just destroy the reactor but can
| turn the facility into a multi-billion dollar cleanup
| effort in minutes.
| PaulHoule wrote:
| Monju was a poorly designed machine which was
| particularly badly run. I recently found a book they
| wrote about it and when I looked at the plans I thought
| "I can't believe they built that in an earthquake zone".
| I don't know if anyone is ever going to build another
| loop-type LMFBR as many of the problems you can have with
| a loop-type can't happen in pool-type reactors.
|
| What was most shocking about the fire at Monju wasn't
| that it happened but that they tried to cover it up.
| Neither that nor the incident where they dropped the
| refueling machine into the reactor vessel were dangerous
| to people off site but the latter sure convinced everyone
| they didn't know what they were doing.
|
| Contrast that to Superphenix where the fuel transfer drum
| failed and they struggled with a steam turbine system
| that was procured under corrupt contracts but overall had
| a good operational record. Or the three pre-1970s cases
| where there was significant fuel damage in the US but
| they found that a core melt in a LFMBR isn't as bad as it
| sounds because the iodine (most dangerous radioactive
| element in the fission products) reacts with the sodium
| and the NaI dissolves in the sodium so it doesn't go
| anywhere. Or EBR-II and the FFTF which performed
| flawlessly, or the highly successful fast reactors in
| Russia.
| skeaker wrote:
| I would liken this to airplanes. They are similarly
| difficult to engineer and maintain, they can also go very
| very badly in mere minutes if operated incorrectly, they
| also have very costly recovery procedures if they crash
| somewhere populated.
|
| For both systems there have been catastrophic accidents
| that were national tragedies, from which we learned a
| lot. "The rules of aviation are written in blood," and
| that is also true for reactors. Past failures like the
| one you linked don't mean that reactors are unsafe; if
| anything, because we had that failure to learn from,
| reactors are now much safer. If we had a volatile
| technology like nuclear reactors and none of them had
| ever had any accidents, then I would be very hesitant to
| have one in my home town since it could very well be the
| first to ever blow up.
|
| I think the reason they have seen a lot of success where
| nuclear reactors haven't is simply up to the fact that
| they are both cheaper to build and that the public can
| very directly see where the benefit to them comes from,
| whereas nuclear power is abstract and indistinguishable
| from coal to the average person.
| crabmusket wrote:
| I agree with your analogy to an extent, but I think it's
| got a very significant flaw.
|
| The consequences of aeroplane disaster are localised in
| space (to the immediate vicinity of the vehicle and
| whatever it crashes into) and time (once the crash has
| happened, it is more or less over).
|
| Nuclear disasters can have global effects, and can last
| for decades.
|
| I'm cautiously pro-nuclear in theory, but am awestruck by
| the incredible forces unleashed and the extreme impact
| they can have when mishandled. It's far more potent than
| anything merely mechanical.
| scythe wrote:
| Bringing up unrelated highly controversial topics is not
| good. It tends to derail threads and accumulate emotionally
| charged, poorly informed comments.
|
| But anyway, leaks of radioactive materials are inherently
| much easier to detect than other kinds of leaks because
| they are radioactive. Every major hospital in the developed
| world has a radiation safety department or equivalent
| performing regular leak and contamination testing in
| association with scintigraphy and brachytherapy, but this
| has not prevented the widespread use of radionuclides in
| medicine.
|
| The notion of "contaminat[ing] everything they touch" is
| also a misconception that the radiation protection
| community has tried to combat for decades: radiation is
| only a meaningful hazard insofar as it reaches levels
| comparable to the natural background radiation produced by
| 40K, 14C, and other sources pervasive in the natural
| environment. There is therefore a level of dilution beyond
| which radioactive contamination ceases to be of meaningful
| concern, just as is true with all other toxic substances.
|
| Source: as a medical physicist in training, I work with a
| radiation safety department at a major US hospital.
| NotYourLawyer wrote:
| Ha, I also remember using a helium canister to look for leaks
| in a vacuum system in the lab. At least ours wasn't at cryo
| temperatures though. Sounds like a real pain.
| phkahler wrote:
| Maybe we should "just" build this in space. ;-)
| wiml wrote:
| Space is far, far too hot at 3 Kelvin, and most of it is too
| high-pressure, too.
| willis936 wrote:
| A good friend of mine made a leak checker from scrap parts
| while I was working at a university lab. It was just for a UHV
| system (no cryo). I wish I still worked with him.
|
| The whizz sound leak checkers make is good fun.
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