8.0 Nuclear Physics

Question 1

Outcomes of the alpha scattering experiment

Answer 1

Calculations of the size of the nucleus

Question 2

Set up of the alpha scattering experiment

Answer 2

Monoenergetic particles fired through a thin gold foil in a vacuum

Question 3

Paths in the alpha scattering experiment

Answer 3

Most passed straight through, some experienced small diffraction, 1 in 10000 had diffraction > 90°

Question 4

Results of the alpha scattering experiment

Answer 4

Atom must contain small concentration of positive charge and mass

Question 5

Properties of alpha radiation

Answer 5

Low penetration and high ionisation

Question 6

Properties of beta radiation

Answer 6

Mid penetration and mid ionisation

Question 7

Properties of gamma radiation

Answer 7

High penetration and low ionisation

Question 8

Identification of radiation

Answer 8

Absorption experiments using penetrative abilities

Question 9

Alpha radiation range

Answer 9

5-10cm, stopped by paper or skin

Question 10

Beta radiation range

Answer 10

1 meter, stopped by a few mm of aluminium

Question 11

Gamma radiation range

Answer 11

Virtually infinite, Stopped by several cm of lead or meters of concrete

Question 12

Inverse-square law for gamma

Answer 12

intensity is inversely proportional to the square of the distance

Question 13

Sources of background radiation

Answer 13

Radon gas, cosmic rays, Medial sources

Question 14

Define spontaneous

Answer 14

Decays occur on their own, without influence by external factors

Question 15

Define random

Answer 15

Decays are unpredictable

Question 16

Decay probability

Answer 16

Probability of decay is constant for a given nucleus

Question 17

N-Z stable line shape

Answer 17

Initially linear along N=Z with curve above N=Z

Question 18

What decay occurs when N > stable line

Answer 18

Beta minus

Question 19

What decay occurs when N < stable line

Answer 19

Beta plus

Question 20

What decay occurs when nucleus is too large

Answer 20

Alpha

Question 21

Release of gamma radiation

Answer 21

After a decay, atom is often excited so releases energy in form of a gamma photon

Question 22

Why is technitium-99m used as a gamma source

Answer 22

Short half life, available, easy to produce

Question 23

Processes for estimating nuclear radius

Answer 23

Closest approach using coulombs law, electron diffraction

Question 24

Uses of alpha particles

Answer 24

Smoke alarms

Question 25

Uses of beta radiation

Answer 25

Detecting width

Question 26

How should sources be stored

Answer 26

in a lead box

Question 27

How should sources be handled

Answer 27

Use handling tools, use low active sources, keep away from others

Question 28

How is the nuclear radius formula derived

Answer 28

From experimental data

Question 29

Define mass difference

Answer 29

the difference between the mass of the nucleus and the total mass of its individual nucleons

Question 30

Define binding energy

Answer 30

the energy required to break a nucleus into its individual protons and neutrons

Question 31

Define nuclear fission

Answer 31

A large nucleus splits into two smaller nuclei, releasing energy

Question 32

Define nuclear fusion

Answer 32

Two light nuclei fuse to form a heavier nucleus, releasing energy

Question 33

What is a thermal neutron

Answer 33

A neutron that is in thermal equilibrium with its surroundings, having less energy

Question 34

Process of induced fission

Answer 34

Nucleus absorbs a neutron, becoming unstable and undergoing fission, releasing energy

Question 35

How can a chain reaction occur during nuclear fission

Answer 35

Neutrons produces by a fission reaction can cause others to undergo fission, repeating into a chain reaction

Question 36

Define critical mass

Answer 36

The minimum amount of material required to sustain a nuclear chain reaction

Question 37

Function of the moderator

Answer 37

To control the energies of the neutrons to improve their ability to cause fission

Question 38

Function of control rods

Answer 38

To control the number of neutrons that are in the reactor

Question 39

Function of the coolant

Answer 39

The substance used to transfer the generated heat

Question 40

Materials of the moderator

Answer 40

Graphite, heavy water, water

Question 41

Materials of the control rods

Answer 41

Boron, silver

Question 42

Fuels used

Answer 42

Uranium (235), Plutonium

Question 43

Protective considerations for nuclear reactions

Answer 43

remote handling, shielding, emergency shut down

Question 44

Nuclear waste management

Answer 44

Cool in water baths, vitrify, store in lead or steel barrels, deep geological disposal

Question 45

What is vitrification

Answer 45

The process of turning nuclear waste into glass to ease the storage process

Question 46

Characteristics of fission fragments

Answer 46

High N/Z ratio