photoelectric effect

Question 1

what is the photoelectric effect

Answer 1

low energy photon interacts with electron and causes it to be ejcted from the atom, leaving hole

an electron from outer shell moves down to fills up the hole, it produces excess energy which is then emitted as an x ray photon

the electron removed is photoelectron

photoelectron escapes with the kinetic energy equal to the difference between the energy of the incident x ray and the binding energy of the electron

Question 2

facts about PEE

Answer 2

totally absorbed

not scattered

occurs with inner shell and tightly bound electron

Question 3

probabilty of PEE

Answer 3

depends on density and z3

x ray energy = binding energy - occurs at its greatest

photon energy less than binding energy - can’t occur

photon energy more than binding energy - rapidly decreases chance

Question 4

condition for PEE

Answer 4

energy of the photon must be the same as binding energy of electrons

Question 5

3 things that occur when x-ray energy increases

Answer 5

increased penetration through tissue without interaction

less pee effect compared to compton

reduced absolute absorption

Question 6

what happens when atomic number of absorber increases

Answer 6

no effect

pee increases proportionally to z3

Question 7

what happens as density of absorber increases

Answer 7

proportional increase in PEE