X-rays & Electrons

[NSX]

@ howstuffworks.com (http://science.howstuffworks.com/x-ray2.htm), it says:

When a speeding electron collides with a tungsten atom, it knocks loose an electron in one of the atom's lower orbitals.

I thought that only photons could knock and electron loose.

How do electrons do the same?

[edit]

Actually, I was viewing this ppt file (http://www.cvm.okstate.edu/~groups/students/web/2001/diagimag/Physics_of_Radiology.ppt), and on slide 22-23, it shows the knocking loose of an electron with another electron as similar to a inelastic collision.

Is this indeed the case?

[wolverine]

Hi

Your electron is interacting with electrons of your atom of tungstem through the electromagnetic force.
He is changing is momentum and losing kinematic energy during this interaction. This energy loss goes to electrons of the tungsten and makes them change of orbitals.

So, indeed, it is an inelastic collision, as in the photoelectric effect (exept that in our case, the photon interacting with the elctron is virtual...)

If you're looking for further informations, you can read the books of Knoll or Leo (interactions of particles and matter)

Bye

[ZapperZ]

I thought that only photons could knock and electron loose.

How do electrons do the same?

You may also want to look up the principle of Secondary Electron Emission. Photomultipliers, scanning electron microscopes, and many other devices make use of the emission of electrons by other electrons. So no, photons are not the only "agent" that can knock out electrons from solids or atoms.

Zz.