Physics Final Interactions Of Ionizing Radiation

Front 1

Define Ionization:

Back 1

-process by which a neutral atom acquires a positive or a negative charge.

Front 2

Define directly ionizing radiation:

Back 2

-CHARGED particles which have sufficient kinetic energy to produce ionization by COLLISION as they penetrate matter.

Front 3

What particles are directly ionizing:

Back 3

-electrons
-protons
-alpha particles

Front 4

Define indirectly ionizing radiation:

Back 4

-UNCHARGED particles liberate directly ionizing particles from matter when they interact with matter.

Front 5

What produces indirectly ionizing radiation?

Back 5

-neutrons
-photons

Front 6

Ionizing photons interact with the atoms of a material or absorber to produce high-speed electrons by 3 major processes:

Back 6

1. photoelectric effect
2. compton effect
3. pair production

Front 7

Define coherent scattering:

-an electromagnetic wave passing near the ____ and setting it into ______.

-the _____ electron reradiates the energy at the _____ frequency as the incident electromagnetic wave.

Back 7

- electron
-oscillation

Front 8

Coherent scattering is probable in (high/low) atomic number materials and with photons of (high/low) energy

Back 8

-high atomic number
-low energy

Front 9

Define Photoelectric effect:

Back 9

- a photon interacts with an atom and ejects one of the orbital electrons from the atom.

Front 10

Photoelectric:
-the ____ energy (hv) of the photon is first absorbed by the atom and then transferred to the atomic electron.

Back 10

-ENTIRE

Front 11

Photoelectric:
-the vacancy left by the ejected electron can be filled by an outer electron which causes __________.

HOWEVER
-The other possibilty is emission of ______ electrons.

Back 11

-characteristic x-rays

-Auger electrons

Front 12

Photoelectric:
-as the photon energy increases, the photoelectrons are emitted in a more ______ direction

Back 12

-forward

Front 13

Photoelectric attenuation strongly depends on the _____ of the absorbing material

Back 13

-atomic number

-also Z^3

Front 14

Define Compton effect:

-The electron receives _____ energy from the photon and is emitted at an angle.

Back 14

-photon interacts with an atomic electron as though it were a "free" electron.

-SOME

Front 15

Compton:
-the photon, with _____ energy, is scattered at and angle too.

Back 15

reduced.

Front 16

Compton:
-the binding energy of the electron is much _____ than the energy of the bombarding photon.

Back 16

-much less

Front 17

COmpton:
-Direct hit:
-Grazing hit:
-90 degree photon scatter:

Back 17

-electron travels forward and the scattered photon travels backward.
-electron emitted at right angles and scattered photon travels forward.
-photon scattered at right angles, angle of electron depends on alpha?

Front 18

Photoelectric effect decreases with increasing photon energy (T/F)

Back 18

TRUE!

Front 19

Compton effect decreases with increasing photon energy (T/F)

Back 19

TRUE!
but it goes, photoelectric and then compton.

Front 20

COmpton is (dependent/independent) of atomic number Z

Back 20

INDEPENDENT

Front 21

What energy must a photon have to cause pair production?

Back 21

1.02 MeV

Front 22

Define pair production:
-how much energy does the photon give up in this interaction?

Back 22

-photon interacts strongly with the electromagnetic field of an atomic nucleus.

-ALL of its energy

Front 23

Pair production:
what does a pair consist of?

Back 23

1 negative electron
and
1 positive electron

Front 24

Heavy charged particles give rise to ____ reactions.

Heavy charged particles therefore produce what?

Back 24

-nuclear

-radioactive nuclides

Front 25

Electrons suffer greater ________ and changes in direction of motion than heavy particles

Back 25

-scattering

Front 26

Bragg Peak is observed for ________ _____ particles but not for ______.

Back 26

-Heavy charged particles
not for
-electrons

Front 27

Neutrons interact with matter by two different ways:
1.
2.

Back 27

1. recoiling protons from hydrogen and recoiling heavy nuclei from other elements

2. nuclear disintegrations