The LHC dumped it’s last fill for the year today at 10:20. The scheduled shutdown wasn’t until 18:00, but they couldn’t get another set of lead ions spinning by then (you can see a small spike around 14:00 below when particles were injected but a “trip” dumped the beam before acceleration began). So, we won’t see new collisions until sometime in March and in the meantime there will be much repairing and updating to both the accelerator and detector.
It was a great year for the LHC and there is nothing but exciting things to expect from the coming year!
It’s so cute when the cafeteria dudes up for a theme week. A few weeks ago we got a mounted bison head, old-West wanted posters, the stars-and-stripes pinned over the crêpe station, and a mannequin wearing chaps and moccasins. Oh, and the only thing vaguely relevant on the menu seemed to be bison haché (bison burgers sans buns–sans buns!).
As I gaze over the beautiful vineyards of Switzerland cradled by French mountains forming a feathered edge in the sunset haze, and as I work into the night trying hard to fully understand one slice of the most energetic particle collisions man has ever produced, this physicist’s thoughts are unfortunately nowhere near Europe and the LHC.
In a few minutes the Fermilab Tevatron Collider (that’s the offical name it gets in all our papers) will be permanently shut down (with a live broadcast and party). I have to diverge from our regularlly scheduled CERN Love to some FNAL Love for a moment.
The Economist’s article “So long and thanks for all the quarks” is a wonderful little ride, from its Douglas Adams opening, snapping every nerd to attention, to its teary, confused, excited ending. We physicists are a very pratical lot; if we are Americans and we can only get our particle collisions in Europe, well then it’s time for more baguettes and cheese! But, from a wider view you really start to wonder if the US is going to be just a bit more lost without such Great Things such as the space shuttle program or the Tevatron.
I spent some time at FNAL, and though I will never miss its cafeteria (“cheap” is the only positive thing I was ever able say) and the lifeless surounding surburbs, it was and still is a little bit magical place. Arriving at dawn, earlier than most, for the start of a shift in the detector control room you might creep past a coyote hopping in and out of the roadside furrows on a hunt. Waiting in shot-setup, as the antiprotons that were created and carefully stored over the entire last night are finally slipped into the Tevatron ring, you tense a little as as you listen to the audio cues from the accelerator. There is a whooosh as each set of bunches load (was that a photon torpedo or an X-wing blast?), sometime later a robot voice announces “ac-cel-er-a-tion,” and finally “col-li-der state: high energy physics.” Later, maybe there will a beer at Two Brother’s Tap House or even a trip into Chicogo (with so much more to offer than Geneva). Always new details of nature to nail down. Always more plots to make. Always more data, until now.
Damn-it, did I just get something in my eye?
The Economist asks, is the future of high energy physics now “For all mankind?” I hope to God or Nature it is. What we do across the praries of Batavia or under the small towns and dairy farms of the Pays de Gex is both very human and very incredible. I wish every last person some taste of it.
If you not going to holiday for the entire month of August on a Greek island then the policy at CERN is that you must sweat until you change your mind. Building 40, where the ATLAS and CMS experimental offices center, has a beauty of a glass dome that turns to beast for 30 minutes every day as you are revealed, Indian Jones style, as the site of the lost ark. Fusion powered theatrical lighting is what we are talking about, in your face. And, the architectural trajectory is not a positive one: a new building, 42, adjoining and expanding on the offices of 40 deals with the heat like sawdust deals with vomit, soaking it up and becoming 100 times as gross.
Building 42 wedges itself on a hillside at the perimeter of CERN, gazing off toward incredible views of a horse training field and vineyards. Its brilliance is the wall of southwest facing windows that soak up the 1000 W/m^2 of bone softening heat from the afternoon sun. This is a good plan in the winter, but the light bulb above your head wilts to a blob of silica and tungsten in the summer. We physicists put our money into high field gradient RF cavities, not air conditioning (at least in these parts). Those shades you see in the photo above operate automatically to prevent the building from technically killing anyone. But, when you are trying not to let your sweat short out your stock Dell keyboard which leaves black spots all over your desk from it’s molten rubber feet, are you really living?
Oh, and look, in the hall is our savior, the water cooler. (A substantial breeze of hot air expanding out into the hallway almost blows you here.) You are going to need at least a few glasses an hour to keep the salts in your blood from crystallizing as the afternoon heats up. But glasses you say? What is that? Such things don’t exist in this part of the world. The spring-loaded cup dispensers on every last one of these gray spigots are fully sprung. The are effectively upside-down water fountains.
Also, don’t even think about getting your own glass from the cafeteria, “IT IS STRICTLY FORBIDDEN TO REMOVE CROCKERY, GLASSES OR CUTLERIES FROM THE RESTAURANT AREA.” OK, I’ll admit disposable cups are also available, but a 10 minute round trip just to acquire a disposable cup just doesn’t feel right.
Anyway, the heat is tappering off for the moment. Let’s hope the transition to mild autumn weather is a long and lingering one.
I do not know these people. They do not uncover any mysteries of universe, at least not ones that clearly need documenting. But, I can at least report that in this context the glowing green “trees” in front of the reception entrance make a lot more sense.
By the way, this is more people wearing CERN badges than I might see at CERN in a month.
Also, it is more dancing.
Do you love tubes and wires? If yes, you have found the correct web page. If no, go stand over there by that concrete block and let me know when you have reconsidered.
A collaboration of particle physics laboratories held a “photowalk” last August (the term is new to me). Groups of photographers received substantial access to CERN, DESY (Germany), Fermilab (USA), KEK (Japan) and TRIUMF (Canada).
[photo: Connection pipe for LHC magnet by Diego Giol]
A snap-shot from last summer: a graveled roof and some conditioning units don’t take away from the fabulous view of the vineyards this coffee break spot provides. Of course the view is just as good from R2 and in theory it has more pleasing surroundings, but in the past that option has had issues.
The LHC is running quite nicely these days. But now I hear it’s “mission accomplished“.
I have a bad feeling about this.
But don’t worry, now this is a mission you too can accomplish at home. it’s time to dust off those double-headed hex keys and reconnect with that one friend of yours who has a truck. At πkia you can affordably complete your lab furnishings while enjoying the meatballs and lingonberries that CERN’s R1 has mercifully failed to provide.
And don’t forget to go to Reddit and get schooled on Swedish.
“A Chip Is Born: Inside a State-of-the-Art Clean Room” from Wired is just good clean nerd fun: bunny suits, sexy stainless steel vessels, yellow lighting so as to “avoid interference with the UV”. The cool stuff even includes a cool lack of stuff,
On the right is one of the large silver pumps used to create extreme vacuums inside the machine — as low as 10-12 atmospheres. (By comparison, the air pressure at 200 kilometers [about 124 miles] above the Earth, where the Space Shuttle orbits, is about a hundred times thicker, at about 10-10 atmospheres.)
Congratulations to them. But, have you heard that the LHC has 27 freakin’ kilometers of beam pipe at 10-10 torr, that’s 10-13 atmospheres, as well as many thousands of cubic meters of insulating vacuum at 10-6 torr (~10-9 atmospheres). Their nothing is a trifle of our nothing.
Of course the reason we need such a pure vacuum is because the proton beams will be circulating in this 27 km tube for hours at a time. Even tiny amounts of gas will lead to unwanted collisions. In small amounts this scattering contributes annoying background and in large amounts it could degrade the beam or contribute heat leading to a quench.
Just the process of creating these extreme vacuums can be pretty interesting. At right you can see a TurboMolecular Pump (diagram & combo), clearly bad-ass. Let me wikipedia that for you. You can get only so far with spinny things, though. The final stage of sweeping up troublesome molecules is accomplished by non-evaporable getter, you can call it NEG to impress your friends. It is just a chemical coating. The NEG is activated in a process called “bake-out.” Heaters temporarily raise the temperature of the vacuum vessel to 350 or 220 C. In bare metal sections the heat releases gas trapped on the surface of the metal. In other sections the heat actives the NEG and stray gas molecules are trapped. You can read a little more in an ATLAS e-News from 2008.
People actually read CERN Love, even when we get busy and don’t update for months, hurray!
Caterina e-mailed with two snapshots from deep in CERN’s crevasses, where no signage can be left unmolested. Of the photos (one above, one below) she writes,
The first one dates back from the summer of ICHEP-hysteria. You are working until 4 am, and you finally get out of B40 to go home, thinking that your 3 hours of sleep are just a bike ride away if you can make it home awake. Then you notice this in the printer in the D corridor. At that point, you think you are already asleep and dreaming, or you are having a mental breakdown.
The second one comes from the LHCb pit. Hold me closer, tiny stick figure on a warning sign.
Congrats for the site, I really like it!
(I like the song reference mainly because I’m a sucker for the “Tiny Dancer” scene from Almost Famous. If, in the wee hours of the morning, a control room breaks out in song I hope you hear it here first.)
Congratulations Geneva, you are one of the top five most expensive cities in the world! This according the Mercer’s 2010 cost of living survey which measures the average cost to someone living abroad for work (such as ourselves).
- Luanda, Angola (1st)
- Tokyo, Japan (2nd)
- N’Djamena, Chad (3rd)
- Moscow, Russia (4th)
- Geneva, Switzerland (5th)
Geneva, you have been slipping since 2003, but the $30 lunches must have made all the difference this year. The CERN cafeteria isn’t quite that steep, but include a glass of wine, dessert, and coffee and you can come pretty close. I remind you that, though the term “restaurant” is sometimes used, in this case you are paying for a fully carry-your-stuff-around-on-a-tray cafeteria experience.
Oh, and yes, it is true that some cash machines dispense the equivalent of $1000 bills, I’ve run across UBS machines that dispenses only 1000 and 500 CHF bills. It’s a very crazy thing to those of us who grew up in America teething on credit cards and completing major drug deals with dramatically stuffed briefcases of paltry $100s.
[photo source: 1suisse on Flickr]
I’m here today to talk about flooring. The kind people walk on. I’ve seen a lot of floors in my time, from the linoleum tile my dear old mother installed all by herself in our humble kitchen when I was a wee lad, all the way to the 2000-year old tile floor in the Vatican Museum that supports millions of visiting feet per year with nary a scratch … after being transported thousands of miles by slaves and horses, that is! I’ve walked on a lot of floors throughout the entire world, and I can say with absolute honesty that every single one of ‘em has succeeded in supporting my weight; that every last one of ‘em has remained flat and avoided caving in under my feet, thanks to the laws of gravity, strong building materials, and good workmanship. Because I say that the only thing you would ever ask a floor to do is, well, nothing at all! You would ask that floor to stay flat and motionless, and to bear your weight across it, repeatedly, for years on end. You would never ask that floor to cave in under your feet; to crumble pathetically under the weight of a hundred kilo or so; to turn to rubble in the course of nominal daily usage. That’s why floor-makers get paid; I’ll go so far as to venture that’s the only reason they get paid. I claim that the only thing required of a floor is not to cave in. Well, if you’re in agreement with that statement, then you’ll agree that the upper floor of CERN’s Restaurant 2 has utterly, abjectly failed in its incredibly simple mission. This is truly the first floor I have ever encountered that has been unable to bear the strain of human feet, and the failure of it and its builders fills me with a deep-seated disgust and enduring concern.
Sorry about all the silence the last couple weeks. These days our day jobs are getting pretty busy.
After the question “what is 7 TeV?” came up in the comments on our imminent collisions post I though it would be fun to take a tour of some common quantities in energy physics. All of this appears in other sources such as “LHC: The Guide” (2008) and, many talks such as “LHC Status and Commission Plans”.
First of all, let’s stay humble. The size of the LHC and its experiments are often enumerated for dramatic effect with numbers like
- 27 km in circumference,
- 100 m underground,
- 8 stories high,
- 12,500 tons, etc.
But all this huge equipment is just support for the diminutive stars:
- bunches of 1011 protons,
- each 7 cm long and 1 mm in diameter (about the size of a mechanical pencil lead).
That really isn’t much stuff considering that macroscopic things contain around 1023 atoms. At rest this bunch of protons is just 1.6×10-13 g of matter. Given this tiny mass and the pencil-lead dimensions you end up with a density of roughly 4×10-7 g/m3, which is absolutely nothing considering that hydrogen gas is 200 million times denser at 90 g/m3 (the LHC can run for many months using the protons from one bottle of hydrogen gas). To increase the odds that these protons run into each other the bunches are focused to a diameter of about 16 μm just before they cross. Still, collisions are rare, with everything running well there will be at best 20 interactions per crossing (and only a tiny fraction of these interactions will be of any interest to scientists). On the otherhand, the LHC can be filled with 2808 bunches spaced about 7 m apart, and with all these bunches moving at just a hair under the speed of light we can end up with 600 million interactions each second.
So, what about this 7 TeV thing? A teraelectronvolt (TeV), or 1012 electronvolts (eV), is a unit of energy. What we are measuring is the energy available in individual proton interactions. The LHC was designed to operate up to 7 TeV per proton, or 14 TeV total. But, for the next couple years the protons will be accelerated up to a speed where each proton carries 3.5 TeV of energy, and for just a moment while two protons collide we will have 7 TeV of energy in one place ready to make new particles (a Higgs boson, dark matter, or maybe something completely new).
A TeV is actually a very tiny amount of energy. A popular analogy is to a flying mosquito, one proton has the same energy as a handful of mosquitoes,
|Kinetic energy of a flying mosquito||0.81 TeV||assuming a 1.5 mg mosquito moving at 1.5 kph|
On the other hand, we have to give these protons some credit. They are a lot smaller than a mosquito. In fact, if you consider energy density these interactions are record breaking. A simple way to look at this is in terms of energy per particle interaction. Chemical energy is what runs batteries, bombs, and us; but chemical reactions involve only around one electronvolt of energy per atom. Potentially, each of the LHC protons brings 7 trillion times more energy to their little party.
|Process||Energy per particle interaction|
|Nuclear fusion||~20000000 eV|
|LHC collision||7000000000000 eV|
Of course there can be quite a few protons spinning around the LHC at one time, and though only a few interact each time the bunches cross, we can wonder how much total energy is in the beam. This is important for two practical reasons that have nothing to do with the science:
- What would happen if the beam were to somehow go astray and hit the beam pipe and surrounding apparatus?
- How can we safely remove the beam in the normal course of work?
The short answer to the first question is pretty simple: bad things. The beam can punch through 2 meters of solid copper [slides 23-25]. But, it should be noted that it is essentially impossible for a person to be hit by a beam, even if they tried. This is because the beam travels in a vacuum pipe that does a very good job of keeping air out, not to mention human hands. In addition, no one can get anywhere close to tunnels with active beam without breaking safety interlocks that cause it to be dumped immediately. The danger is really only to the equipment. Of course they found exceptions to this in Soviet Russia.
When it’s time to inject a fresh beam of protons or the beam must be removed quickly for safety it is diverted toward a very large chunk of carbon that is liquid cooled and shielded in a 1000 tons of metal and concrete. A nice article about the beam dumps can be found in IEEE Spectrum.
So, to the energies…
|Energy in a head-on highway collision||1 MJ||cars each 1 metric ton moving at 115 kph|
|LHC: Energy in one beam||173 MJ||2808 bunches, 1.1×1011 p/bunch, 3.5 TeV|
|Energy in chocolate consumed by two Swiss people per year||244 MJ||22.4 lbs of chocolate / year / person in Switzerland|
|Energy required to melt 1 ton of copper from room temp.||620 MJ||Wikipedia: 63 g/mol, 24 J/mol/K, 13 kJ/mol|
|Kinetic energy of freight train moving at 60 kph||1400 MJ||100 cars, 100 tons each|
|LHC: Energy in the ATLAS’ toroidal magnetic field||1600 MJ||source: ATLAS e-News|
|Chemical energy in 1 metric ton of TNT||4600 MJ||Wikipedia: Trinitrotoluene|
|LHC: Energy in the magnetic field of all the LHC dipoles||11000 MJ||source: slide 12|
|Chemical energy in 1 metric ton of dark chocolate||24000 MJ||USDA: search for ‘chocolate 60-69%’|
You will notice that for all this crazy amount of energy in the beam (almost 200 car-accidents worth) there are even bigger energies lurking at the LHC. The magnetic field of the ATLAS toroid stores 10 times as much energy, and 10 times beyond that is the energy stored in all the LHC magnets. In fact, the average pair of Swiss people consume more energy every year in chocolate than our measly beams can provide.
(One thing I love about these numbers has nothing to do with high energy physics: you might have been surprised that there is over 5 times as much energy in chocolate as there is in TNT. What is important about an explosion is not as much that a lot of energy is released, but instead that it is released very quickly.)
Well, today’s the day! The LHC people have decided, along with all the experimenters, that it’s time to collide some protons at 7 TeV. Actually, the hoopla was originally scheduled to start this morning at 09h00 (CERN time). That plan was amended several times, so that physicists I talked to all had different ideas of the actual start time for colliding the beams (I heard 03h00 at some point). The initial attempts this morning to ramp the beam have both failed due to unforeseen errors in the quench protection system (QPS) and some other electronics, but they’re now saying they expect beam (and collisions!) to be ready around noon or 13h00. So, that means that our early risers in the US might be privy to all the good shit.
For your viewing pleasure, we’ve compiled a list of links to various webcasts broadcasting the day’s activities:
- LHC First Physics Webcast (be sure to click around to the various webcams, at the bottom of the page)
- Our beloved OP Vistars (Page1 is often the most informative)
- CMS cameras: One Two Three
- ATLAS public page, home to a nice feed and some pretty pictures
- ATLAS event displays
- A pretty informative CERN Twitter feed
- The LHC Announcer (this dude talks to you about the LHC activities)
So, click away. We’ll try to keep you updated, maybe copying some of the pretty photos of the day here for you to see. Let us know if you find other interesting webcasts to link here, either by commenting or by e-mailing firstname.lastname@example.org.
UPDATE: We have collisions! At 13h22, the LHC people declared “STABLE BEAMS,” and we’ve been seeing 7 TeV collisions ever since. The press release is here, and the champagne is everywhere.
I present to you “the most inane conversation ever captured on camera,” all thanks to CERN. I’ll start the video at 5:36 for some setup, but the really relevant bit is at 7:26, a transcript of which follows,
Fearne: What’d you want to talk about. We can talk about anything.
Peaches: Ummm, the Large Hadron Collider.
Fearne: The what?
Peaches: You know they have made this thing called the Large Hadron Collider. It’s in Texas or something, where they are trying to create a black hole in space.
Fearne: Right, you want to talk about space.
Fearne: Go for it.
Peaches: Well, I’ve always been interested in Quantum physics, and about theories of, you know, how we came to be and why… Um, which is I guess how I got involved in spirituality and stuff and that way and the religious path I choose to go down and stuff.
Fearne: Which is what?
Peaches: I don’t want to talk about it.
[later] I am a scientologist, I’ve been a scientologist for a while now.
[Thanks to Reddit]
About a week ago, the LHC was preparing itself for its inaugural 2010 current ramp to values consistent with 3.5 TeV energy proton beams. While this was simply an opening act for the feature presentation (actual 3.5 TeV + 3.5 TeV collisions) next week, it certainly was an exciting and optimistic event celebrated widely at CERN and around the world. Record energies were reached in the field of particle acceleration, and the timing was perfect considering the growing awareness of the 2010-2011 LHC physics programme.
One media outlet that decided to express its enthusiasm for the huge success of the LHC’s initial foray into the high energy realm was the British online newspaper The Telegraph. Here is the article they published the day after the successful 3.5 TeV commissioning; really, things are pretty tame in this write-up — catchy headline, video of cute physicists, and lots of fervent anticipation for next week’s collision extravaganza. However, when this article first appeared on the website of The Telegraph, their elation with the world record breaking energy ramp-up was much more apparent:
If that didn’t strike you as odd, have a look at that headline one more time.
Actually, this is quite a natural joke to be made, if you think about it. I was surprised to find that, while ‘large hadron collider’ yields around 900k Google hits, ‘large hardon collider’ only finds 63.4k! I can only hope that our fellow internet comrades will up the efforts to capitalize on this goldmine. Sexual innuendos mix quite well with physics jargon. How do you think the term hadron was derived in the first place? I feel like we’re not far from hearing the phrases ‘beam dump’ and ‘that’s what she said’ used together quite regularly.
On the other hand, the top hit of that Google search surely sets the bar pretty high: http://largehardoncollider.com/
Everyone knows that bunnies are cute and fluffy; why then do human-constructed likenesses of them turn out to be so utterly terrifying? Appearing harmless and adorable in nature, a bunny writ large is at best creepy and at worst, devastating. And yet we insist on creating ever larger monuments to the long-eared ones. It’s possible that our widespread practices of rabbit idolatry perversely reflect some deep and ancient animosity between the races; after all, a child’s first impulse, when given a small (possibly edible) bunny effigy, is to bite off its head. Like other dangerous and potentially world-ending pursuits, CERN finds itself right in the center of the ongoing human vs. bunny struggle, with rabbit flesh prominently featured as a dish on the lab’s rotating menu. Now the world’s tallest chocolate bunny has been erected a stone’s throw away from the LHC in the outskirts of Geneva. Physicists and laypersons alike were encouraged to worship at the feet of this delicious and unholy monstrosity. While other countries may claim to have constructed the most massive, I sincerely doubt anyone can beat this 5-meter tall chocolate bunny.
I fear that our overweening pride has not only threatened the destruction of the universe, but that this graven image shall reach unto the heavens as the ancient tower of Babel, its pointy ears penetrating the event horizon of some intergalactic time warp, bringing down Armageddon upon our heads.