Why do alpha particles experience large angle deflections?

[zincsulphide]

Homework Statement

I would like to understand why alpha particles experience large angle deflections and if this is the same thing as recoil of alpha particles? Do large angle deflections occur near the end of the alpha particle track or can they occur at any point along the trajectory?

Homework Equations

None

The Attempt at a Solution

I think that large angle deflections occur due to Coulomb repulsion from a positively charged nucleus in the absorbing medium. I think that the term "recoil" means the same thing and deflections can occur at any point on the trajectory, but I am not sure...

Thanks

 

[mfb]

Recoil is what the nucleus experiences that emits the alpha particle.

I think that large angle deflections occur due to Coulomb repulsion from a positively charged nucleus in the absorbing medium.

Right.

 

[Andrew Mason]

Homework Statement

I would like to understand why alpha particles experience large angle deflections and if this is the same thing as recoil of alpha particles? Do large angle deflections occur near the end of the alpha particle track or can they occur at any point along the trajectory?

Homework Equations

None

The Attempt at a Solution

I think that large angle deflections occur due to Coulomb repulsion from a positively charged nucleus in the absorbing medium. I think that the term "recoil" means the same thing and deflections can occur at any point on the trajectory, but I am not sure...

The Coulomb repulsion explains why the collision between the alpha particle and a nucleus is elastic - i.e. the particles deflect away from each other. But the large angle deflections are the result of their relative masses. If an alpha particle were to collide with another alpha particle, the angle between the directions of the two alpha particles after collision would be 90°. It is because the incident alpha particle is less massive than the nucleus that it collides with (gold, in the case of the Rutherford experiment) that the alpha particles deflect at angles larger than 90 degrees.

Welcome to PF, by the way!

AM