I need help calculating the number of Electrons? (Current/Electron Density/Velocity)

1. Oct 2, 2012

bmb2009

1. The problem statement, all variables and given/known data

How many protons are in the beam traveling at the speed of light in the Tevatron at Fermilab, which is carrying 11.17 mA of current around the 6.3-km circumference of the main Tevatron ring?
2. Relevant equations

Not sure...

3. The attempt at a solution

I don't know how to calculate the the protons (electrons). I tried multiple different things but al the equations I have use the Cross Sectional area value (A) which can't be found from the given information.

I tried manipulating such equations as

current density = (number of electrons)(e)(drift velocity)

and other similar equations but the all contain some form of the value of A?

2. Oct 2, 2012

voko

Re: I need help calculating the number of Electrons? (Current/Electron Density/Veloci

What is current?

3. Oct 2, 2012

Liquidxlax

Re: I need help calculating the number of Electrons? (Current/Electron Density/Veloci

and how do you find J {current density} from I {current} and a circumference?

4. Oct 2, 2012

voko

Re: I need help calculating the number of Electrons? (Current/Electron Density/Veloci

What is the significance of current density here?

5. Oct 2, 2012

bmb2009

Re: I need help calculating the number of Electrons? (Current/Electron Density/Veloci

Ok got it! Thank You!!