Taking a closer look at LHC

In this section we present some simple calculations in order to compare LHC energy with some more familiar situations. In the section Relativity  a more detailed discussion about the energy in a collider (like LHC) can be found in relativistic terms.

 How much energy are we talking about?

7 TeV = 7·1012 eV · 1,6·10-19 J/eV = 1,12·10-6 J

It doesn´t look like a lot of energy

For the ALICE experiment, each ion of Pb-208 reaches 1150/2 = 575 TeV.

So, the energy per nucleon is: 575/208 = 2,76 TeV

Let´s calculate the kinetic energy of an insect of 60 mg flying at 20 cm/s:

Ek = ½ m·v2     Ek = ½ 6·10-5·0,2 2  ~ 7 TeV

That  is, in LHC each proton will reach an energy similar to that of an annoying ... MOSQUITO!

But we have to keep in mind that this mosquito has 36 thousand trillion nucleons, whereas the 7 TeV in the LHC will be concentrate in one sole proton.

Maybe this comparison is not very convincing so let´s look at it from another point of view.

Let´s calculate the energy present in each bunch:

7 TeV/protón·1,15·1011 protons/bunch ~1,29·105 J/bunch

A powerful motorbike 150 kg travelling at 150 km/h_

Ek = ½ ·150 · 41,72 ~ 1,29·105 J

So if a bunch of protons collides with you the impact is similar to that produced by a powerful motorbike travelling at 150 km/h.

If you are lucky to avoid that "0,2 picogram motorbike", don´t worry, there are 2807 following it. And if you decide to change lanes, the equivalent is coming in the opposite direction.


Another calculation which can show the enormous amount of energy reached is:
1,29·105 J / bunch  x 2808 bunches ~ 360 MJ
-Stored beam energy-
 And that is equivalent to

77,4 kg  of  TNT

The energy content of TNT is 4.68MJ/kg (Beveridge 1998).


The Heat of Fusion of Gold is: ΔHF = 63,71 kJ/kg

So, 360 MJ are enough to melt: 5650 kg    5,65 Tonnes of gold.

Obviously such an amount of energy can not be supplied instantlyIn fact the process lasts over 20 min through a chain of different accelerators.


Xabier Cid Vidal, PhD in experimental Particle Physics for Santiago University (USC). Research Fellow in experimental Particle Physics at CERN from January 2013 to Decembre 2015. Currently, he is in USC Particle Physics Department (Spanish Postdoctoral Junior Grants Programme).

Ramon Cid Manzano, secondary school Physics Teacher at IES de SAR (Santiago - Spain), and part-time Lecturer (Profesor Asociado) in Faculty of Education at the University of Santiago (Spain). He has a Degree in Physics and in Chemistry, and is PhD for Santiago University (USC).



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