lots-o-love
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Posts by lots-o-love
Thanks for all the protons!
0The 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!
Bison haché and some chaps on a mannequin
0It’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!).
Is that dust in both my eyes?
0As 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.

Sweaty summer
0If 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.
Every day I’m shufflin’
3I 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.
Particle physics photowalk
1
Here’s a low content, high pixel post for you…
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).
The resulting Flickr stream is impressive.
[photo: Connection pipe for LHC magnet by Diego Giol]
Coffee breaks everywhere
1A 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.
Mission accomplished
0The 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.
The HÄDRÖNN CJÖLIDDER is here (leveling feet sold separately).
And don’t forget to go to Reddit and get schooled on Swedish.
That sucking sound
0
“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.
Feed me a stray dancer
1People 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.)
Conference room
2CERN certainly isn’t hurting for conference rooms. This is especially true when any loading dock and hallway can easily serve the purpose.
Geneva, where cash machines dispense $1000 bills
1Congratulations 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]
Chocolate bar yardstick
1Sorry 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,
| Energy | Amount | Notes |
|---|---|---|
| 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 |
|---|---|
| Chemistry | ~1 eV |
| 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 | Amount | Notes |
|---|---|---|
| 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.)
Cheezburger → ← LHC
4I have to give a shout-out to I Can Haz Large Hadron Collider. My favorite image from the site is the following; needless to say, it is the apex of all our hopes and dreams as physicists.
Diner conversations everywhere
5I 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.
Peaches: Yeah.
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]
Finding your way around CERN
1
We have already noted that “the building numbers here don’t make a damn bit of sense. If they do follow any kind of scheme, it’s not a scheme that helps you find buildings.” So, suppose you have a workshop to attend in the AB auditorium in building 6. You might know where building 5 is, but one learns very quickly that that sort of information doesn’t do you the tiniest bit of good at CERN. Instead, your only resource is undoubtedly the ancient “WWW Map” of CERN.
(By the way, I once spent twenty minutes wandering the halls of building 6 trying to find the infamous AB auditorium. Not to be outdone, at CERN the room numbers can be just as confusing as the building numbers.)
I actually find CERN’s building map page mostly effective and a cute little throwback to a time before Google Maps. It’s the horseshoe crab of web pages, ugly but effective. Go ahead and open Netscape 1.0 (or maybe something even older) and find yourself a building, if that happens to be your thing. It’s all just GIFs and links (image maps are used in some places, but not nearly as much as you would expect), and most of the time it gets you where you need to go.
Of course though, there are some serious and silly limitations,
- Clicking top map zooms out revealing the only other zoom level available. Clicking bottom maps inexplicably takes you back to the home page. Panning is never an option.
- If you land in the Prevessin site the bottom right map doesn’t indicate this at all. From the home page try CERN Clubs Spaces > Picnic area; if you don’t have an inkling that this is on the Prevessin site then you are going to be very confused for a while.
- The orientations of the other two maps are not consistent with the the overview map in the bottom right (the only one with north properly straight up). Why they did this I don’t have a clue; my only guess is that they wanted to layout the Meyrin site a little more horizontally. This is a big reason why the previous picnic area example is so confusing, the shape of the Prevessin site is not as obvious when presented in multiple orientations.
- At least at first glance, there are no simple everything-in-a-pdf versions of the maps. There is a very prominent link to a 3D PDF that takes a while to download and render, after which you realize the 3D in this case is a useless gimmick. I have run across a PDF with 3D content a total of zero times outside of this page; there must be a very good reason for this. Actually, there are PDF maps of all the sites, but the only place you can find them is via a very subtle link at the bottom of the map page after you have clicked on a point of interest or searched for a building. There is no link at all from the main page. (Contrary to what it says, they are accessible outside of CERN, one slightly pleasant surprise.)
Hoping to discover what other information might be available, I found my way to the GS Department Patrimony and Site Information page. The page is littered with promising links that when poked reveal themselves to be dead and rotting. But, there is one handy find: a GPS navigation page provides a CSV file with the latitude and longitude of all the buildings for uploading to your navigation system. (Relevant to the discussion in our building number post, there is also a page listing the construction date of each of the buildings, but that page is not accessible outside of CERN so I won’t bother linking.)
Finally, a tip: keep watching CERN Love. We are working on a geographical component to the site that hopefully will be handy and informative. We also hope to publish some interactive informational pages that will be very relevant to the start up of the LHC. Both should appear in the next couple weeks.
The LHC thrust deep into our cultural consciousness
1Congratulations CERN media relations, someone in Spain is clearly drinking your Kool-Aid (or Flavor Aid, it seems history is unclear).
Remember that smutty detector porn that CERN started feeding the media a few years back? The stuff where our super-conducting toroids are laid bare, nothing left to your nerdy imagination. How can you not forget?
Here, let me introduce you to an old friend, it may have a temporary word with your techno-thalamus,
This image can be found in the ATLAS barrel magnet gallery as well as in every media packet ever distributed by CERN. If you are a heavy pop-sci consumer you senses are probably already deadened to it. (Do you remember your mom warning you about this stuff back when you were 13? She should have.) Well, if you browsed the magnet gallery just a little bit too long then you might be struck by a jarring final image like this
This is from what seems have been a very short lived production of Hector Berlioz’s Les Troyens at the Palau de les Arts in Valencia, Spain. It’s the classic legend of Troy and Carthage in the form of opera, but this very contemporary production seems to have been ripped from the science and technology section of your local paper by the same people who brought you Battlefield Earth. According to one review the theater company directing the production “was received with mixed applause and boos.” After watching the following montage of the production–where it seems bits of every sci-fi drama ever produced was collided at near the speed of light, irradiating the performers, and transporting them back to college in which everyone is issued a MacBook–I think I would be applauding and booing at the same time, both loudly. The ATLAS toroid scene is at 1:09,
[By the way, if you want to learn more about this theater company, La Fura dels Baus, and you decide to visit their web site at www.lafura.com, you might take into consideration the fact that you will be treated to immediate full screen video. If you are lucky (or unlucky, depending on your setting and sensibilities) the random clip will include nudity or even simulated sex. Good times.]
Correction: as the first comment points out, I originally put “Palau de les Arts” where I meant “La Fura dels Baus” in the last paragraph.
Where are my robot hands?
1Earlier we discussed the LHC’s current robot monorail, little TIM, but 30 years ago CERN had far loftier goals and they were all about getting grabby. What follows are some photos grudgingly requinquished by CERN’s document server. The first one is my favorite, because this fellow is clearly living the 1981 dream.
Ever wish you could just shoot your arms through an iron-impregnated concrete wall and shake some sense into that radioactive pressure vessel on the other side? In 1981 you could.
The robot arms were eventually upgraded and attached to both monorails and trucks tethered by umbilical cord. “MANTIS’ as it was known, has more photos in CDS. You can also read more at “MANTIS – a compact mobile remote-handling system for accelerator halls and tunnels”, “MANTIS 2 : a new long range remote vehicle and servo-master-slave manipulator for the CERN accelerator complex” and “Teleoperator evolution at CERN”.
Reading some of those documents, MANTIS sounds like a really handy guy. Maybe that is why he was eventually incorporated into the military-industrial complex; given complex reasoning skills; and, through some fortune, jolted into a zest for more than just the life of a radioactive science-slave or autonomous killing machine. CERN was the crucible in which was forged one who “is alive”, a crafty, cultured cowboy. We miss you, Johnny Five!
Farm life and accelerators
4The highest energy accelerators in the world cover a lot of ground. The LHC tunnel passes mostly hidden under pasture and a few small farms, but even right in the middle of the laboratories, assembly buildings, and offices of CERN’s Meyrin site one finds a flock of sheep. The sheep rotate through a few disjoint grassy patches small enough that I really start to wonder if it’s worth the trouble. CERN’s sibling over in the US, Fermilab, hosts on its grounds some even more substantial farm and wildlife: bison, horses, deer (though the population was heavily culled a few years back to make the roads safer) and some ponds well stocked with fish and frequented by herons.
At least one person has relayed the speculation that the animals are primarily present to allay local’s fears of radiation: if sheep can spend all day snacking on top of an accelerator then how dangerous can it be? The problem I have with this theory is that it makes no mention of the scientists who spend just as much time in just as much proximity to our scary science stuff. Does the public honestly think we are so driven to distraction by our whizzing particles that we might very well hang our balls in the beam to see if it tickles? Let me go on record and say definitively, no, we are not.
Below I present evidence of how deadly serious the Fermilab-CERN competition is.
Potential for future study:
- Apply a Lotka–Volterra model to the CERN and Fermilab scientific populations.
- Cite this blog post as the only motivation.
- Win Ig Nobel prize (for a physicist of my meager stature, the equivalent of ‘profit’).
That is unless one of our five highly esteemed readers scoops me on this. I dare you.






















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