3.2.1 Particles

Question 1

What force keeps the nucleus stable?

Answer 1

Strong nuclear force

Question 2

What is the range of strong nuclear force at which it is; repulsive, attractive and COMPLETELY ineffective

Answer 2

Below 0.5fm, between 0.5-3fm, above 3fm

Question 3

Why was the neutrino first hypothesised?
and what is it?

Answer 3

.To account for the change in energy during beta decay
.It is a particle with no mass or charge but has KE therefore conserving energy

Question 4

Describe pair production

Answer 4

a gamma photon with sufficient energy(roughly 2x the rest energy of the particle it’s trying to pair produce) is near the nucleus.
This creates a particle and its antiparticle (to conserve charge) dependant on the energy of the photon.
Any excess energy is converted to KE and distributed evenly

Question 5

What is required for alpha decay to occur?
And why is this required?

Answer 5

.The nucleus must be large e.g. radium
.This is required so that the SNF can’t keep the nucleus stable

Question 6

What is required for beta minus decay?
And why is this required?

Answer 6

.The nucleus must be neutron rich
.this is so that a neutron can change into a proton

Question 7

What is emitted in alpha decay?

Answer 7

A helium nucleus
/
2 protons and 2 neutrons

Question 8

What happens in beta decay?

Answer 8

A neutron changes into a proton
An electron is emitted from the nucleus
An electron anti-neutrino is also emitted

Question 9

What are the two types of neutrinos?

Answer 9

Electron neutrino
Muon neutrino

Question 10

What is needed for gamma decay to occur?

Answer 10

A nucleus with excess energy(normally after alpha or beta decay)

Question 11

What are gamma rays made of?

Answer 11

High energy EM waves that don’t change the nucleus at all

Question 12

What is the anti particle of:
Proton, electron, neutron, neutrino

Answer 12

Antiproton, positron, antineutron, antineutrino

Question 13

What can EM radiation behave as?

Answer 13

A wave or a particle
Known as wave particle duality

Question 14

Define a photon

Answer 14

A packet of EM radiation with no mass or charge

Question 15

Antiparticle and particle (opposite or same):
Mass
Charge
Rest energy

Answer 15

Same
Opposite
Same

Question 16

Describe one application of annihilation

Answer 16

PET scanners
Used in medicine to detect cancerous tumours as if you inject a tracer that emits positrons annihilation will occur with the electrons found naturally in the body. Cancer cells will absorb this tracer at a faster rate and so this area will emit more photons as a result of annihilation. Therefore the location of the tumour can be detected by scamners

Question 17

What are the four fundamental forces?

Answer 17

Strong nuclear force, gravity, electromagnetic force, weak nuclear force)

Question 18

What are the 2 requirements for particle interaction?

Answer 18

One of the four fundamental forces
An exchange particle

Question 19

What is the other name for an exchange particle?

Answer 19

Gauge boson

Question 20

What is an exchange particles purpose?

Answer 20

It moves between two particles using momentum and so gives rise to a force between the particles.

Question 21

What is the ;exchange particle, particles affected, range and strength of strong nuclear force

Answer 21

Virtual Pions,hadrons,10 to the -15m, strongest

Question 22

What is the exchange particle, particles affected ,range and strength of electromagnetic force?

Answer 22

Virtual photon (y), any with a charge, infinite, 2nd strongest

Question 23

What is the exchange particle, particles affected ,range and strength of weak nuclear force?

Answer 23

W+ and W- bosons, everything, 10^-18m, 3rd strongest

Question 24

What is the exchange particle, particles affected ,range and strength of gravity?

Answer 24

Graviton(theoretical), any with mass, infinite, weakest

Question 25

What is the rule of mass and range for exchange particles

Answer 25

The larger the mass the shorter the range (Inversely proportional)

Question 26

What is the Feynman diagram for beta minus decay?

Answer 26

Click me [link](https://mmerevise.co.uk/app/uploads/2022/11/beta-minus-feynman-1024x805.png)

Question 27

What is the Feynman diagram for beta plus decay?

Answer 27

Click me [link](https://mmerevise.co.uk/app/uploads/2022/11/beta-plus-feynman-1024x805.png)

Question 28

What is the Feynman diagram for electron capture?

Answer 28

Click me [link](https://digestiblenotes.com/images/physics/alevel/feynman6.png)

Question 29

What is the Feynman diagram for electron-proton collisions?

Answer 29

Click me [link](https://digestiblenotes.com/images/physics/alevel/feynman7.png)

Question 30

What are leptons key characteristics

Answer 30

They don’t experience snf They are fundamental particles

Question 31

Name 2 leptons

Answer 31

Electrons Muons

Question 32

What are the key characteristics of hadrons

Answer 32

They experience snf They are made up of quarks

Question 33

What defines the sub groups of hadrons

Answer 33

Baryons have 3 quarks Mesons have a quark antiquark pair

Question 34

Name 2 baryons

Answer 34

Protons Neutrons

Question 35

Name 2 mesons

Answer 35

Pions Kaons

Question 36

What must be conserved in particle interactions?

Answer 36

Baryon number Lepton number Strangeness (only in strong nuclear interactions) Charge Energy Momentum

Question 37

Why do kaons have a strange property and what does this cause

Answer 37

They have a longer lifetime than expected This causes them to only be produced in pairs of strange particles

Question 38

How can strangeness change in weak interactions?

Answer 38

-1, 0, +1

Question 39

How much mass and charge do neutrinos have?

Answer 39

Zero or almost zero Zero

Question 40

What are the three types of quarks (excluding antiquarks)

Answer 40

Up, down and strange

Question 41

Which quark has greater mass

Answer 41

Strange and anti strange quarks

Question 42

What is the quark composition of a proton?

Answer 42

UUD

Question 43

What is the quark composition of a neutron?

Answer 43

UDD

Question 44

What is the quark composition of a pion?

Answer 44

U(U) D(D) () = anti

Question 45

What is the quark composition of a kaon?

Answer 45

K+ u(s) K- (u)s K0 d(s) / (d)s / = or () = anti

Question 46

What is the strangeness of k+ and Ko

Answer 46

+1

Question 47

What is the strangeness of K- and (Ko)? () = anti

Answer 47

-1

Question 48

How does quark character change in B+ decay?

Answer 48

An up quark changes into a down quark

Question 49

How does quark character change in B- decay?

Answer 49

A down quark changes into a up quark

Question 50

Describe nuclide notation

Answer 50

a X z Where a = nucleon number(mass number) X = the chemical symbol of the element z = atomic number(proton number)

Question 51

Define isotopes

Answer 51

Atoms of the same element (defined by the number of protons) but different numbers of neutrons

Question 52

Describe annihilation

Answer 52

When a particle meets its equivalent anti particle they are both destroyed and all their mass is converted to energy in the form of (at least) two gamma ray photons which move apart in opposite directions to conserve momentum

Question 53

What does exchange particles being virtual mean?

Answer 53

They only exist for a short time and cannot be detected

Question 54

What do all baryons eventually decay into?

Answer 54

Protons

Question 55

What do mesons decay into?

Answer 55

Pions

Question 56

What do leptons decay into?

Answer 56

Electrons

Question 57

How are strange particles produced/ decay

Answer 57

Produced: strong interaction Decay: weak interaction

Question 58

Why does particle physics rely on large teams?

Answer 58

Peer review

Question 59

Describe mass energy conservation

Answer 59

If there is a decrease in mass during an interaction there must be an increase in energy to compensate for this (and vice versa).

Question 60

Why must pair production occur near the nucleus?

Answer 60

So that momentum is conserved by the nucleus recoiling opposite to the direction of the particle anti-particle pair.

Question 61

Why must strange particles be produced in pairs?

Answer 61

Strange particles are produced during the strong interaction which requires the strange number to be conserved. Therefore particles must be produced in pairs and these particles must have opposite strangeness (1/-1) to ensure strangeness remains constant throughout the reaction

Question 62

Describe quark confinement

Answer 62

It’s impossible for quarks to exist in isolation because as you supply enough energy to split the quarks apart there would first be enough to pair produce a meson which would use up the energy making it impossible to reach the energy required to free a quark.