# From where this number of 14 Tev has arised for proton-proton head on collision in LHC?

I am interested in finding out, why are collisions at 14TeV done in the LHC, instead of some other energy?

• public.web.cern.ch/public/en/lhc/lhc-en.html – John Rennie Jul 6 '12 at 9:21
• Note that this years running is at $4\text{ TeV}$ per beam, not $7$, leading to a current CoM energy of $8\text{ TeV}$. – dmckee Jul 6 '12 at 12:17
• Hi Poonam, and welcome to Physics Stack Exchange! We generally prefer that you ask one question per post. To help you out, I removed the extra questions that were separate from your main question. Feel free to post them individually as separate posts, but do check our higgs-boson questions first to see if some of what you want to know has already been answered. – David Z Jul 6 '12 at 17:28

This year, the LHC is running at $8\text{ TeV}$. The energy of the beam is limited by the current in the magnets that steer the beam. The faster the particles travel, the higher the magnetic field has to be to turn them.
• This is not really true. Though these events are rare (very rare!), there are $x_{1,2} > 1$ events; that is you can occasionally get parton collision energies to approach the arbitrarily close to the beam energy (and for the momentum transfer to exceed the beam momentum). If you are not familiar with this concept the $x$ there is "Bjorken scaling variable" also known as the light-cone momentum fraction. – dmckee Sep 13 '14 at 23:21