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Whilst studying cosmic rays (CRs) and the influence of the sun on the intensity of the CRs, I read that solar modulation mainly affects low-energy CR-particles. Could someone maybe explain to me why this is the case? Why aren't high-energy particles affected by the solar modulation?

I thought that the force exerted by the magnetic field of the sun was proportional to a particle's velocity, hence would have greater impact on a particle with higher energy (velocity). Or should I also look at the mass of the particles?

Thanks in advance

R3E1W4
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1 Answers1

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Yes, the Lorentz force is proportional to velocity, but the centripetal force is proportional to velocity squared. Thus, when you equate both, you find that the magnetic gyroradius is proportional to velocity, $r=\frac{mv}{qB}$. Hence, lower-energy particles have smaller gyroradii and can get trapped or deflected. In contrast, higher-energy particles are less affected by the magnetic field.

rfl
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