electrons

Question 1

what are the 4 main types of electron interactions as they go through a medium

Answer 1

elastic collisions with nucleus
inelastic collisions with nucleus
elastic collisions atomic electrons
inelastic collisions with atomic electrons

Question 2

what happens in elastic collisions with the nucleus

Answer 2

electron passes by nucleus at a distance and is deflected from its path but no energy loss occurs

Question 3

which of the 4 effects that occurs at the scattering foils

Answer 3

elastic collisions with the nucleus

Question 4

what happens in inelastic collisions with the nucleus

Answer 4

• electron passes very near the nucleus and its path is changed and it loses energy due to deceleration
• rare
• brems!

Question 5

what happens with elastic collisions with atomic electrons

Answer 5

• incident electron is deflected but energy is not lost

- negligible with energies greater than 100eV

Question 6

what happens with inelastic collisions with atomic electrons

Answer 6

• energy transferred by incident electron causes ionization or excitation ofthe atomic electron
• collisional energy losses
• proportional to Z

Question 7

what is a delta ray

Answer 7

an electron that comes due to the interaction of the photon with another atom

Question 8

radiation losses/brems are approx proportional to the ____ _____ and and to ___

Answer 8

electron energy

Z^2

Question 9

define stopping power

Answer 9

energy lost per path length

sum of collisions and rad losses

Question 10

what does stopping power depend on

Answer 10

Z material and energy of electrons

Question 11

does an electron go on forever?

Answer 11

no it is eventually captured by surrounding atoms

Question 12

what are 2 ways to widen the pencil beam

Answer 12

scattering foils

scanning beams