Nuclear Physics and Particles

Question 1

How do you calculate the mass defect of a nucleus?

Answer 1

The mass defect of a nucleus is defined as the difference between the mass of the separated nucleons and the combined mass of the nucleus.

Question 2

What is nuclear fusion?

Answer 2

is the combining of the two light nuclei to produce a heavier nucleus.

Question 3

What is nuclear fission?

Answer 3

is the disintegration of a heavy nucleus into two lighter nuclei of approximately equal masses.

Question 4

Define radioactive decay

Answer 4

is the spontaneous decaying of the nucleus of an atom which results in the emission of particles.

Question 5

What is background radiation?

Answer 5

Ionizing radiation emitted from a variety of natural and artificial radiation sources. It should be constant isotropic and uniform

Question 6

What is the activity of a sample?

Answer 6

The activity of a radioactive substance is defined as the average number of atoms disintegrating per unit time.

Question 6

What is the activity of a sample?

Answer 6

The activity of a radioactive substance is defined as the average number of atoms decaying per unit time.

Question 7

What is the decay constant?

Answer 7

The decay constant λ of a nucleus is defined as its probability of decay per unit time

Question 8

Define half-life

Answer 8

Half-life is defined as the time taken for half the original number of radioactive nuclei to decay

Question 9

Explain the role of the moderator

Answer 9

The moderator slows down fast neutrons making them thermal neutrons to make fission more likely to happen.

Question 10

What are possible materials for the moderator?

Answer 10

Water, Graphite.

Question 11

What is the role of the control rods?

Answer 11

Reduce the number of neutron in the fission reactor

Question 12

What are possible material for control rods?

Answer 12

Boron and Cadmium

Question 13

Define the Nuclear Binding Energy

Answer 13

Nuclear binding energy is the energy required to disassemble a nucleus into the free, unbound neutrons and protons it is composed of

Question 14

proton number

Answer 14

number of protons in the nucleus of an atom (a.k.a. atomic number)

Question 15

nucleon number

Answer 15

number of neutrons and protons in the nucleus of an atom (a.k.a. mass number)

Question 16

What are Isotopes

Answer 16

Different forms of the same element or nuclei having the same number of protons with different
numbers of neutrons

Question 17

Which group of particles are subject to the weak nuclear force but not the strong nuclear force

Answer 17

Leptons

Question 18

What is the quark composition of a meson?

Answer 18

A quark and an antiquark.

Question 19

Which force do Hadrons decay by?

Answer 19

The weak nuclear force.

Question 20

What is the quark composition of a Baryon

Answer 20

Three quarks

Question 21

What is a neutrino?

Answer 21

A lepton with no charge and a tiny mass.

Question 22

Why doesn’t a neutrino experience the electromagnetic force?

Answer 22

They have no charge.

Question 23

What is the quark composition of a neutron?

Answer 23

up down down (udd)

Question 24

What is the quark composition of a proton?

Answer 24

up up down (uud)

Question 25

What is the quark composition of an anti-baryon?

Answer 25

Three antiquarks

Question 26

Name the two types of hadron.

Answer 26

baryons and mesons

Question 27

What force hold quarks together in hadrons?

Answer 27

The strong nuclear force.

Question 28

What is the family of particles that are subject to both the strong and weak nuclear force?

Answer 28

Hadrons

Question 29

What type of particle are nucleons?

Answer 29

Baryons

Question 30

How does a proton compare to an antiproton?

Answer 30

he have the same mass but opposite charge.

Question 31

How does an electron compare to a positron?

Answer 31

The have the same mass but opposite charge.

Question 32

What is the antiparticle of the electron?

Answer 32

Positron.

Question 33

Describe beta minus decay.

Answer 33

A neutron in an unstable nucleus decays into a proton, electron and electron antineutrino.

Question 34

Describe beta plus decay.

Answer 34

A proton in an unstable nucleus decays into a neutron, positron and an electron neutrino.

Question 35

What quark transformation occurs during beta minus decay?

Answer 35

A down quark (in a neutron) turns into an up quark (in a proton)

Question 36

What quark transformation occurs during beta plus decay

Answer 36

An up quark (in a proton) turns into an down quark (in a neutron)

Question 37

What is the maximum range of the strong nuclear force?

Answer 37

~3fm

Question 38

Below what distance is the strong nuclear force repulsive?

Answer 38

0.5fm

Question 39

How did Rutherford estimate the maximum radius of the nucleus?

Answer 39

He equated the KE of the alpha particle to the electric potential energy at closest approach to the nucleus.

Question 40

What material was used as a target in Rutherford's scattering experiment?

Answer 40

Gold foil, a few atoms thick

Question 41

What was measured in Rutherford's scattering experiment?

Answer 41

The angle of deflection of the alpha particles.

Question 42

What happened to most of the alpha particles in Rutherford's scattering experiment?

Answer 42

They passed straight through the foil (with very little scattering).

Question 43

What proportion of alpha particles were scattered in Rutherford's scattering experiment?

Answer 43

Around 1 in 2000

Question 44

What proportion of alpha particles were deflected by more than 90° in Rutherford's scattering experiment?

Answer 44

Around 1 in 10,000

Question 45

What was concluded due to most of the alpha particles passing straight through the gold foil Rutherford's scattering experiment?

Answer 45

Most of the atom is empty space with most of the mass concentrated in a small nucleus.

Question 46

What was concluded due to some alpha particles being scattered in Rutherford's scattering experiment?

Answer 46

The nucleus is positively charged.

Question 47

How did Rutherford estimate the maximum radius of the nucleus?

Answer 47

He equated the KE of the alpha particle to the electric potential energy at closest approach to the nucleus.

Question 48

How has the radius of the nucleus been measured?

Answer 48

By the diffraction of fast moving electron.

Question 49

What is R in R = r₀A^(1/3)?

Answer 49

The radius of the nucleus.

Question 50

What is r₀ in R = r₀A^(1/3) roughly equivalent to?

Answer 50

The radius of a proton.

Question 51

What is A in R = r₀A^(1/3)

Answer 51

Nucleon number.