Help 1: Energy units
You are probably familiar with using Joule as a measure of energy. In particle physics, however, we use something called electron volt (eV) instead . The reason we use this is that the energies we are measuring in particle collisions are very small and are related to the energies of single particles. The definition of an electron volt is the kinetic energy a single electron gets by moving through an electric potential of 1V. We get the following relation between Joule and one electron volt:

conversion of eV into J


We often use energies which are of the order of several million electron volts so it is convenient to introduce the following

Mega electron volt
Giga electron volt
Tera electron volt
Peta electron volt


Conversion
To convert let's say 14 TeV (proton-proton collision energy at LHC when at full operation) to Joule you use the formula just above and you get:

14 TeV
14 TeV in J
14 TeV in J


which is pretty much the energy of a flying mosquito!

Now what if you have a measurement in Joule and want to convert it into eV? You simply do:

conversion of J in eV


So you see, 1 Joule is about 6 thousand PeV. 1 Joule is how much kinetic energy a small apple attains after falling 1 meter in earths gravity.

Exercise (answers can be found at bottom of page)
  1. Convert 10 GeV into Joule.
  2. Convert 100 Joule into eV.


Here you get back to the measurement's main page.