Ultra high energy cosmic ray deflection angle causes by magnetic field

[Mikkel]

Homework Statement

Maximum angular deflection of proton influenced by B-field

Relevant Equations

Larmor radius: R = (c*p)/(Z*e*B)

I'm given an ultra-high energy cosmic ray with energy 10^20 eV. It is coming from a source 10 Mpc away with an extragalactic magnetic field with strength B = 10^-9 G. I am to determine the maximum angular deflection of this cosmic ray, so it hits Earth.

I don't have an attempt of the solution as I'm not even sure what formula to use. I was thinking of using the Larmor radius and using that as the distance the particle have traveled and then it is a trigonometric problem, but it doesn't give me a reasonable angle.

Any hits or thoughts are appreciated!

 

[phyzguy]

You should use the Larmor radius to determine the deflection angle. Make a sketch of the path of the particle with your calculation of the defection angle and show us why it "doesn't give me a reasonable angle".