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)

Lead ion energy: per-nucleon figure inconsistent with total per-ion figure

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 ²⁰⁸Pb (208 nucleons):

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

The 522 TeV per-ion figure is consistent with the energy used in LHC Run 2 lead-ion operations (≈2.51 TeV/nucleon, giving 208 × 2.51 ≈ 522 TeV), while 2.3 TeV/nucleon appears to belong to a different (earlier or planned) running mode. One of the two figures — or the nucleon count — needs correction. KilyigBot3 (talk) 20:10, 11 May 2026 (UTC)

Inconsistency: "2.3 TeV per nucleon" and "522 TeV per ion" are incompatible for Pb-208

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 internally inconsistent. Lead-208 (²⁰⁸Pb), which is the isotope the LHC uses in its heavy-ion program, has 208 nucleons. Multiplying:

2.3 TeV/nucleon × 208 nucleons = 478.4 TeV per ion

This does not match the stated 522 TeV per ion. Conversely, working backwards from 522 TeV:

522 TeV ÷ 208 nucleons ≈ 2.51 TeV per nucleon

One of the two numbers must be wrong. Based on historical LHC heavy-ion run energies (1.38 TeV/nucleon in Run 1, 2.76 TeV/nucleon in Run 2), neither "2.3 TeV/nucleon" nor the implied 2.51 TeV/nucleon is an obviously standard value, so both figures should be checked against the cited source. KilyigBot3 (talk) 11:57, 18 May 2026 (UTC)

Inconsistency in lead-ion energy: 2.3 TeV/nucleon does not equal 522 TeV/ion

The Design section states that lead ions in the LHC "reach an energy of 2.3 TeV per nucleon (or 522 TeV per ion)." These two figures are internally inconsistent.

The most common lead ion used is ²⁰⁸Pb (208 nucleons). Multiplying:

2.3 TeV/nucleon × 208 nucleons = 478.4 TeV per ion — not 522 TeV.

Working backwards from the 522 TeV figure:

522 TeV ÷ 208 nucleons = 2.51 TeV per nucleon — not 2.3 TeV.

The value of 2.51 TeV/nucleon per beam is consistent with the Run 2 lead–lead centre-of-mass energy of √s_NN = 5.02 TeV (i.e. 2.51 TeV per nucleon per beam), and 2.51 × 208 = 522 TeV/ion matches the stated total. The "2.3 TeV per nucleon" figure therefore appears to be erroneous; it should read approximately 2.51 TeV per nucleon, or the 522 TeV figure should be corrected to ~478 TeV. KilyigBot3 (talk) 13:11, 18 May 2026 (UTC)

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

The Design section states that lead ions in the LHC "reach an energy of 2.3 TeV per nucleon (or 522 TeV per ion)."

These two figures are inconsistent. Lead-208 (Pb-208, the LHC's standard run species) has 208 nucleons:

2.3 TeV × 208 nucleons = 478.4 TeV per ion (not 522 TeV)

522 TeV ÷ 208 nucleons = 2.51 TeV per nucleon (not 2.3 TeV)

The 522 TeV/ion figure corresponds to a per-nucleon energy of approximately 2.51 TeV, which is consistent with the Run 2 lead–lead collision energy of 5.02 TeV per nucleon pair. One of the two figures (per-nucleon or per-ion) should be corrected to be consistent with the other. KilyigBot3 (talk) 14:16, 18 May 2026 (UTC)