Talk:Large Electron–Positron Collider

Tevatron

 * The article says this is the most powerful particle accelerator ever built, but Tevatron is the highest energy collider, at 1TeV I know this to be true, at over double the energies LEP could priduce, so surely isnt tevatron the most powerful particle accelerator?


 * The Tevatron accelerated hadrons (such as protons) instead of leptons (such as electrons). LEP was the most powerful lepton accelerator ever built.  The two types of accelerators allow different kinds of measurements.  In general, for the same amount of money you can build a hadron collider that will reach heavier particles (higher discovery threshold) or a lepton collider that can perform more accurate measurements within its energy range.  68.178.59.178 (talk) 18:31, 24 November 2008 (UTC)

Mass Increase of Particles
My understanding is that the view that particles gain mass as their speeds increase isn't used much now, mainly due to the confusion over rest and relativistic mass. For example it certainly isn't taught that way in my lectures, or see http://math.ucr.edu/home/baez/physics/Relativity/SR/mass.html. I think my rewording of this part makes the text clearer anyway, as it is the energies of the particles that is important - the relativistic mass increase isn't directly an issue. —The preceding unsigned comment was added by Pagw (talk • contribs) 21:48, 9 August 2007 (UTC)
 * Yes, your most recent edit seems better. By the way, you can sign your comments by putting ~ at the end. -- SCZenz 14:03, 10 August 2007 (UTC)
 * Oops I just forgot to sign...
 * Pagw 14:29, 10 August 2007 (UTC) :-)
 * It isn't so much used at lower gamma. In this case, one usually just mentions the energy, but at high gamma the relativistic mass is proportional to energy. Sometimes momentum is important, which is also proportional at high enough gamma. Note the common notation of specifying mass in energy units. Gah4 (talk) 13:51, 27 September 2020 (UTC)
 * It isn't so much used at lower gamma. In this case, one usually just mentions the energy, but at high gamma the relativistic mass is proportional to energy. Sometimes momentum is important, which is also proportional at high enough gamma. Note the common notation of specifying mass in energy units. Gah4 (talk) 13:51, 27 September 2020 (UTC)

Broken Link
It might be worth noting that the majority of links (pertaining to the relevant information) from * LEP Operations (Archives)are not working or have simply become redundant. I would make the change myself but just incase this is only temporary ill leave it be for someone else to confirm. Cheers. Grimwires 13:42, 5 October 2007 (UTC)

On the topic of broken links, opal.web.cern.ch just takes the user to a login page. Not exactly great for the credibility of some statements. StudiousGoblin (talk) 13:31, 8 December 2021 (UTC)

Unsourced citation
I can't help with the quote (it's impossible to google the source for anything that's been on Wikipedia for a while...), but the gist of it is certainly true. Citing Precision Electroweak Measurements on the Z Resonance (hep-ex/0509008):

Numerous potential causes of shifts in the centre-of-mass energy were investigated, and some unexpected sources identified. These include the effects of earth tides generated by the moon and sun, and local geological deformations following heavy rainfall or changes in the level of Lake Geneva. While the beam orbit length was constrained by the RF accelerating system, the focusing quadrupoles were fixed to the earth and moved with respect to the beam, changing the effective total bending magnetic field and the beam energy by 10 MeV over several hours. Leakage currents from electric trains operating in the vicinity provoked a gradual change in the bending field of the main dipoles, directly affecting the beam energy.

Maybe somebody wants to repurpose this into the article? Themel (talk) 12:09, 21 August 2009 (UTC)

Building of the Tunnels...
There seems to be no information about building LEP and in particular the tunnels. How long did this take etc? —Preceding unsigned comment added by MrBlueHouse (talk • contribs) 00:15, 24 January 2010 (UTC)

Speed record
Although now far surpassed in energy, I believe LEP still holds the particle speed record for accelerators. I am not certain if the 209 GeV peak energy attained, currently quoted in the article, is the center-of-mass collision energy, or particle energy per beam; the 1990 reference I just added mentions future possible upgrades to 130 GeV per beam, but I assume only that per beam energy is more than 209/2 = 104.5 GeV. Then, inverting the formula for the Lorentz factor, I find v > (1.0 - 1.2e-11)c ~ 3.6 mm/s. I hope this will be considered an uncontroversially trivial physics calculation; it makes use of sqrt(1-ε) ~ 1-(ε/2), to order ε2, if ε is small. It would be better to find a reference, and I hope someone can do that. (The information has to be available in the final LEP results papers after the 2000 shutdown, in the arXiv, which I have not attempted to search.) But I think the record is interesting, and I don't see much around at this late date, even on the CERN pages, not even on the basic distinction between beam and COM energy. If LEP reached 209 GeV per beam, that would basically halve the (c - v) gap, to ~6e-12c. Wwheaton (talk) 19:36, 3 April 2010 (UTC)

Hadron collider
At the top, above the image it says `hadron collider`. Shouldn't it be `lepton collider`? — Preceding unsigned comment added by Bloemelau (talk • contribs) 16:10, 22 January 2016 (UTC)


 * fixed 134.158.19.80 (talk) 16:12, 29 June 2018 (UTC)

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rings or not
As the article notes, with rings you have many chances for collision. However, with linear colliders, such as the SLC, you can focus to a much smaller spot, so you get a higher collision density with your one shot. Gah4 (talk) 13:56, 27 September 2020 (UTC)