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What Are Must-Sees For Open Day At the LHC?
ribasushi writes "The last open day at the Large Hadron Collider is one week away. While I have a solid chance to go, I am dumbstruck by the insane amount of things to see during the 10 hours of the event. Since I do not know all that much about physics, I am turning to the knowledgeable crowd here at Slashdot — what do you think are the most awesome 5 must-see things on the agenda next Sunday?"
At the SLAC you can walk the length and they have an observation room exactly where the high speed particles will collide. You will want to see that part, where the sceintists will observe and whatever else you can learn. Hope to hear about your visit-maybe you'll see the Higgs or be able to visualize a magnetic field (like around when a lightning bolt strikes)-protected ofcourse! From the pictures, it must be an overwhelmingly awesome personal experience size-wise. (And a few days ago I was in awe seeing, again, how grand the Roman Statues are currently in the US on loan:))
If you have any interest at all in the detectors or accelerator, now's the time. Spend your time there; because, you won't be able to "tour" it later. Once it's been running the equipment will become activated (as in radioactive) and the public will no longer be able to tour the underground facilities. There will likely be physicists and technicians on hand who will be happy (excited even) to talk about what they've built.
you can always go back and look at the computer center, control rooms, or whatever at a future open house event (which I'm certain they'll have regularly, to keep the public interested).
For what it's worth, I worked as a technician at a U.S. DOE facility
I went to LHC on a visit (school field trip by all standards) just last week and there's quite a lot to see indeed. I would also recommend the detectors especially since they're probably the most important part of the whole experiment and they also include a visit of the actual LHC tunnel. The two sites I would recommend are those in Meyrin where the main campus is (their cafeteria is pretty decent as well) and where the ATLAS experiment is located. While it may be quite impressive to see it, ATLAS is unfortunately closed so besides tons of cable and the external muon chambers you won't get to see much of the inner workings. However, most of the conferences seem to be concentrated around the campus area. There's also the Microcosm exhibit which, while somewhat simple, will probably be entertaining if you don't have a lot of experience with physics (especially the experimental setups). However, you must go see the CMS experiment at the Cessy site just because it's still open (well, it was last Wednesday) so you get to see the actual interior of the detector. Also, I think CMS is simpler to understand just because it's got a simpler setup than ATLAS. Only problem is Cessy is somewhat far from the main campus (not to mention it's in another country), but they will probably have some shuttles (not the "space" type) around for this. If you still have time, ALICE is probably interesting as well and it's located at the Crozet site. But you should have your schedule full with the two main detectors.
Black holes are not invisible on two accounts.
1- They emit black body radiation at the Hawkings temperature due to quantum evaporation, which for a tiny black hole is very high. A black hole created by an accelerator, composed of the mass of a few particles would likely be extremely hot for a very short time, and so would emit gamma rays. Wikipedia has the calculation for a 1kg BH : the lifetime is approximately 10^{-16} seconds, and the energy output equivalent to the complete anihilation of the 1kg mass (you don't want to be around). Small black holes are *fierce*, however subatomic ones don't really matter. After all accelerators anihiliate particles all the time.
The above is the #1 reason BH potentially created by accelerators are not a concern.
2- Even very large BH are in fact directly visible. They reflect light better than a highly polished metallic sphere.
These two facts are direct illustrations that most people, including well-educated scientists, don't know the first thing about BH.
Since I work here.... I might give a few clues:
:-)
- before you do anything, check the Microcosm museum in the reception building. This one will explain a lot what's happening.
- this one is a must: be sure to make a trip to either the ATLAS or CMS cavern (those are the two bigger detectors attached to the LHC)
- the ATLAS control room
- the LHC control room
- the computing centre in the IT building
- and if you have time, stop by for a tea in building 40
I took part in their summer student programme last year and during that time we've been visiting all of the places that you can go visit now during the open day. My recommendations are: ...
..." - it's somewhere in building 2 if I remember correctly.
If you're interested in detectors you have enough time to visit at least two of the four major experiments. CMS is a bit far away, it takes you some 20 minutes by bus to go there, ALICE and LHCb are closer and ATLAS is just across the road opposite the main entrance. I would recommend ALICE and ATLAS - ATLAS is, just like CMS, a multi-purpose detector looking for everything that's interesting in the unknown lands of energies accessible at the LHC whereas ALICE aims to study quark-gluon plasma produced in the collisions of heavy nuclei. Make sure to visit ATLAS last - if you thought the other detectors were huge ATLAS will blow you away!
Don't count on it that you get a peak inside the actual LHC tunnel while you are visiting the detectors. I don't know why but all of our guides were quite reluctant to just pull back the curtains so that we could have a look. Maybe there's a designated visit during the open day
For lunch go to restaurant 1 and enjoy the atmosphere there. It was one of our favourite places to hang out and have a fruit salad. It is always told that many ideas for experiments and theories first came up over a cup of coffee there, it's an exciting place and your chance to chat with some of the physicists there.
There's also a kind of graveyard for old parts of experiments close to the reception. I found the Gargamelle bubble chamber most impressive, a massive biest.
Last but not least try to visit the accelerator chain (LINAC, PS) - it's quite interesting to see the bottle containing the hydrogen that goes into the different accelerators and will eventually be accelerated to these mind-boggling energies.
Wherever you go and whatever you see, have a fun day at CERN - i sure envy you.
Kilian
PS: Oh, and it's always nice to see the sign saying: "In one of these offices Tim Berners Lee invented the internet
I'm a student here working on ATLAS (and I'll be one of the volunteers on the 6th) and I agree with the parent. The two big 'Must sees' are the detectors and the accelerators. The detectors are going to be much more impresive looking. That said, here's my $0.02
ATLAS (point1). This is the biggest detector (and my favorite, though I'm not biased or anything....) but it will also be the most crowded by far.
CMS (point5). Almost as big as ATLAS and still damn impressive. It won't be as crowded because it's a lot further away. It will still be packed though I'm sure.
ALICE (point2). Smaller detector for heavy ions. My guess is this will be pretty crowded to since St Genis is close to CERN
LHCb (point8). Another smaller detector for b quark physics. Between Ferney and Meyrin... no idea if people will go see it.
Those are the 4 detectors ranked (in my opinion) in order of coolness. I'd try to go see 2 of them if you can. Look up info on them online (they all have websites), find out which ones you want to visit. You should also try to see the accelerator somewhere. Point 6 would be my recomendation since the beam dump is also located there (this is where the beam is evacuated in case of emergency. When you realize the energy stored in the beam, this becomes pretty impressive).
Another thing I recomend is the acelerator chain tour (point1):
http://lhc2008.web.cern.ch/LHC2008/OpenDaysE/accelerators.html
There are a lot of other things open, but most of them you can still go and visit when the LHC is running (and the crowds aren't there). One last recomendation. I'd start out going to see things out on the ring, then come back to point1 (Meyrin) and explore it with all the rest of your time. That way you should be able to get the most out of it. See you Sunday!
[NSFW] http://synthesismagazine.net/wp-content/uploads/2008/03/large_hardon_collider.jpg
Well, OK. I can claim to be one... But I will out of own for the Open Day... unfortunately.
The thing is that at CERN almost everyone is clueful but about "one thing" mostly. It is hard to find someone who has the "large picture"... The ones who do are generally people who have not been working on the LHC for the past 15 years but those who have been working on it since 2-3 years and before that was working at Fermilab or somewhere else like that. Then they can tell you what's new or revolutionary and put things in better perspective.
Honestly, it looks like the OpenDay will be a mad house. We are expecting at least 40,000 people. The queues are going to be awfully long! I feel like we should have a couple more of these OpenDays to accommodate this huge interest but hey, I am not in the management!! I am just a post-doc!
That said, I have given lots of tours at CERN already. I have taken at least 400 people underground just this past year. (Only 12 people are allowed to go at a time with one guide... ) I think the well-known things like ATLAS and CMS will be completely and utterly packed. So I would like to point out a rare gem... It's the LHC-b cavern where you can actually see the insides of the experiment which installed before LHC-b was installed and is now decommissioned and sitting nearby. The problem with ATLAS and CMS is that they are "done" -- meaning, the experiments are assembled wholly and therefore, it is hard to see it's guts. But you can see the guts of this decommissioned detector, which is kind of neat. I work for ATLAS and I love ATLAS to pieces but I think to try to see it on Open Day, one would need to be at CERN and queueing at 8am... or earlier.
If you have never seen a tape reader with robots running around before, the tour to the Computing Center is really cool -- but then again, since there will be no radiation there, you can visit that even after the 1st of May. (1st of May is the date set by the LHC management board to be the last day of public tours to the LHC and experiments. The rest of CERN will still be "visitable" after that.)
If you can not see ATLAS or CMS on the OpenDay or cant be here on the OpenDay but want to see them, there is a cheat... Most of everyone's requests goes through CERN Visitors Service. And they have a pool of guides but the experiments also have a pool of guides. The visitors service is no longer offering tours as they are completely booked until the 1st of May with their guides. But the experiments might still allow for visitors. The way to increase your chances of getting a private tour to one of the experiments is as follows: Find 11 other people who are interested in seeing the experiment with you and then e-mail the ATLAS or CMS secretariat asking for a tour for 12 people on a April xxth at xx:xx. Then they will forward this request to their pool of guides and someone (like me) might actually give you a tour. We like 12 people tours as this is the maximum we can take down and it is a much better "waste" of our time if the tour group is at maximum number... The e-mails for the secretariats are as follows: atlas.secretariat@cern.ch and cms.secretariat@cern.ch
Good luck!
I am a theoretical physicist and 1) is entirely correct while 2 is misleading at least.
First what is a black hole? Let's say we mean the event horizon. That does not reflect light at all. However, the gravitational field surrounding the BH will of course deflect light the same way the gravitational field around a massive star for example would. Therefore the OP was entirely correct, we can only see the effect of the gravitational field but not light emanating from the BH itself. (At least for astronomical BHs that are very massive and have correspondingly low Hawking temperature). Even taking Hawking temperature into account a BH never reflects light, it has a temperature and gives off perfect black body radiation (in the semi-classical approximation which is the only thing we really know about). That is the black hole information paradox, the outgoing radiation seems to have no information about the ingoing one.
A super-massive blackhole in empty space would be one of the darkest objects you could think of (arbitrarily cold, negative specific heat, yadda yadda). Put some infalling matter around it and you get very bright and energetic processes so BHs can power very bright objects in their vincinity. Put some galaxies and stars behind it and it can lense the light coming from these, put some stars in front it and it can deflect a small amount of light so strongly that it comes straight back at you. That is really due to the space time structure induced by its mass, you don't need a BH for either of these effects. Furthermore you wouldn't say a lense is very bright would you? Nor that it reflects light.