Talk:Particle accelerator

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Should collider be merged here?[edit]

All particle colliders are particle accelerators, and I don't think there are many particle accelerators that do not perform collision experiments. Collider is a stub article so whatever useful content it has (if any) should be merged her and the article should just redirect here. At least IMHO. TimothyRias (talk) 09:19, 8 April 2010 (UTC)

It could be that particle colliders are a class of accelerator that collide two beams. I have to check, but I think that's the case. In this sense, I'm suggesting that collider is in error. However, I still agree that they are types of accelerators. It's basically a question of length and if the term collider is used explicitly to mean impinging two or more beams together. Consider the LHC: it's got collider in the name, and it's colliding two beams together. As it stands, the article is not too long for inclusion here, but in principle someone might expand on the subject (if indeed it is the specific case of merging two beams), and then it's better to make a short summary here and keep that page. I'm not a high energy guy, so I'm not much use besides commenting, sorry! DAID (talk) 13:23, 8 April 2010 (UTC)
I'm not sure that collider is used exclusively for setups that collide beams together. Of course that is the setup for any modern collider doing collision experiments, simply because fixed target setups have such a low center of mass energy compared to the energy you put in. A quick google search, seems that at least some people make the explicit distinction between "collider" and "fixed target" setups. TimothyRias (talk) 15:21, 8 April 2010 (UTC)
Colliders (and the term does always mean colliding beam accelerators) are sufficiently important and specialized that they probably do deserve an article of their own, but the present collider article is wrong-headed. The main issue with colliders is not relativity, but conservation of both momentum and energy. The old Bevatron wanted to make anti-protons, which would seem to require only twice 0.938 GeV, but it needed over 6 GeV because you have to conserve momentum in a collision between a beam and stationary target proton, so you have to look at the energy available in the C.M. frame. If I recall the available energy in the CM for a fixed target (of the same mass) scales as the square root of the beam particle energy, so colliding beams are a big win. The big loss is intensity, since beams have much lower density than targets. There, focusing the beams down to the smallest possible size at the collision point is critical. For the LHC, this is ~16 microns, if I recall. Explaining all this is why a separate article seems warranted, but I can't do it now; maybe someone else can. For now I think we might just redirect collider here, and build the more specialized article later. Wwheaton (talk) 21:27, 8 April 2010 (UTC)

Electrostatic accelerators are the most common claim[edit]

I wrote this today, and I'm pretty sure it's true, but someone may ask how I can verify this. I have a 250 page book on 'Research Facilities in Nuclear Physics.' Although published in 2003, I can count how many of each kind of accelerator there are. It was a study by the International Union of Pure and Applied Physics, so I think it should be a fine source. If you are extremely skeptical of my claim before I've counted in the book, you can delete the material from the page until I confirm. However, the number of tandems is extremely high. A number of years ago, practically every major university in the United States had one, for example, although now some of them have been shipped elsewhere. Some universities have or have had 2 of them! I've talked to friends who are attending school at various places, and they don't even know there's a tandem at their school. In fact, my father has been working at the same university for about 15 years now (Education department), and when I was visiting their tandem over winter break he said to me, "I didn't even know we had one." This is literally how common they are! Yes, I know maybe this first hand accounts are not verifiable, and I will count in this book very soon to confirm and cite! DAID (talk) 11:48, 8 April 2010 (UTC)

By pure chance today I happened across the statistics I put in just now on accelerator types & uses, which I have added. Despite the obvious fact that almost all of this article deals with the 1% that are high-energy research machines, I think the term "particle accelerator" does generally refer to just that 1%, but maybe lowering the energy threshold to ? ~30 MeV ? to catch some cyclotrons and linacs.
I don't have a serious problem that we spend a lot of time discussing the smaller percentage of machines. Despite that I work in low energy, I wouldn't say all machines are equal.
A holdover from this article two years ago is a bunch of photos of DC accelerators that the article now goes out of its way to declare are not linear accelerators at all. I think the article should probably begin the lead with a classic in-tunnel photo of the LHC as most representative, and also have nice photos of a Van de Graaf, a linac, a cyclotron, and a classic weak-focusing synchrotron (? Cosmotron or Bevatron?) appropriately placed. Wwheaton (talk) 22:00, 8 April 2010 (UTC)
I'm not sure the LHC is 'most representative' but I don't oppose whatever images people like to show. I don't really worry about pictures much myself. However, I may consider to move the DC photos to the electrostatic nuclear accelerator page. Thoughts? DAID (talk) 10:40, 9 April 2010 (UTC)
I think putting those low-energy DC accelerator pix in the electrostatic nuclear accelerator page would be good. How about renaming "electrostatic nuclear accelerator" to "electrostatic particle accelerator"? The vast majority of those are apparently not used for nuclear physics or research any more, and the others seem to be mostly for industrial or medical, therapeutic use. At least one image, probably the Van de Graaf, should be kept here I think. I envisage an LHC picture in the lead here as it seems the current iconic particle accelerator, and the state-of-the-art, though Lawrence's original 10 cm cyclotron might be equally appropriate. What do you think about the "atom smasher" debate above BTW? I would put some of the historical info in that I described in that discussion (and maybe move the historical section up after the "Uses" section?) but I need to reference it a bit. Wwheaton (talk) 14:18, 9 April 2010 (UTC)

Automatic archiving?[edit]

This page has some really old threads. Would anybody mind if I setup automated archiving for threads older than say 6 months? TimothyRias (talk) 15:29, 8 April 2010 (UTC)

Six months sounds good to me. Bill Wwheaton (talk) 20:58, 8 April 2010 (UTC)
This seems good. We have many discussions of the same matter, and I have become confused as to where to discuss topics with multiple threads. Thank you. DAID (talk) 10:36, 9 April 2010 (UTC)

Notes[edit]

I copied the sentence Synchrocyclotrons have not been built since the isochronous cyclotron was developed. from the article Synchrocyclotron. See that article's history for attribution. BR84 (talk) 21:30, 13 January 2012 (UTC)

Relativistic mass[edit]

Part of the article says this:

To reach still higher energies, with relativistic mass approaching or exceeding the rest mass of the particles

But doesn't relativistic mass always exceed rest mass? Does the article mean additional mass from relativistic effects rather than just relativistic mass? David (talk) 17:11, 6 January 2013 (UTC)