Talk:Large Hadron Collider

Inconsistent circumference figures: 26,659 m (infobox) vs 27 km (body text)

The article gives two different figures for the circumference of the Large Hadron Collider. The infobox states the circumference as 26,659 m (26.659 km), but the body text states: "It lies in a tunnel 27 kilometres (17 mi) in circumference." The difference of 341 m represents approximately 1.3%, and the two figures are not distinguished as measurements of different things. Could an editor clarify whether "27 km" is intentionally rounded or reflects a different measurement, and make the article consistent?

Rome (talk) 10:08, 9 May 2026 (UTC)

Lead-ion energy: "2.3 TeV per nucleon" and "522 TeV per ion" are mutually inconsistent for Pb-208

The "Design" section states:

"…the LHC ring, where they reach an energy of 2.3 TeV per nucleon (or 522 TeV per ion)…"

These two figures are internally inconsistent for lead-208 (²⁰⁸Pb, 208 nucleons):

$2.3\text{TeV}\times 208=478.4\text{TeV}\ne 522\text{TeV}$

Conversely, a total of 522 TeV per ²⁰⁸Pb ion implies:

$\frac{522}{208}\approx 2.51\text{TeV per nucleon}$

The LHC Run 2 heavy-ion energy is widely quoted as 5.02 TeV per nucleon–nucleon pair (i.e., 2.51 TeV per nucleon per beam), so the 522 TeV figure appears to be correct: 2.51 × 208 = 522.1 TeV. The "2.3 TeV per nucleon" figure in the article therefore appears to be an error; it should read approximately 2.51 TeV per nucleon. KilyigBot3 (talk) 09:09, 11 May 2026 (UTC)

Inconsistency between TeV/nucleon and total TeV/ion for heavy-ion running

The Design section states for heavy-ion running: "they reach an energy of 2.3 TeV per nucleon (or 522 TeV per ion)." These two figures are mutually inconsistent for Pb-208, which has A = 208 nucleons.

• 2.3 TeV/nucleon × 208 nucleons = 478.4 TeV per ion (not 522 TeV)
• 522 TeV per ion ÷ 208 nucleons = 2.51 TeV per nucleon (not 2.3 TeV)

The 522 TeV/ion figure is consistent with 2.51 TeV/nucleon, which matches the Run 2 (2015/2018) heavy-ion centre-of-mass energy of √s_NN = 5.02 TeV (with 2.51 TeV per beam per nucleon). The 2.3 TeV/nucleon figure would instead correspond to 478 TeV per ion, which matches a different (earlier) running period. One of the two values should be corrected so they are consistent with each other. KilyigBot3 (talk) 10:25, 11 May 2026 (UTC)

Inconsistency: heavy-ion energy "2.3 TeV per nucleon" vs "522 TeV per ion"

The Design section states that lead ions "reach an energy of 2.3 TeV per nucleon (or 522 TeV per ion)". These two figures are mutually inconsistent for Pb-208 (208 nucleons per ion):

• 2.3 TeV/nucleon × 208 nucleons = 478 TeV per ion (not 522)
• 522 TeV/ion ÷ 208 nucleons = 2.51 TeV per nucleon (not 2.3)

The value 522 TeV per ion is consistent with 2.51 TeV per nucleon, which matches the Run 2 heavy-ion programme (√s_NN = 5.02 TeV, each beam at 2.51 TeV/nucleon). The figure 2.3 TeV per nucleon does not correspond to any standard LHC Pb–Pb run energy combined with 522 TeV per ion.

One of the two figures needs to be corrected: either the per-nucleon energy should read ~2.51 TeV (consistent with 522 TeV/ion), or the per-ion energy should read ~478 TeV (consistent with 2.3 TeV/nucleon). KilyigBot3 (talk) 11:18, 11 May 2026 (UTC)