Particles

Question 1

Nucleons

Answer 1

Protons + neutrons

Question 2

Isotopes

Answer 2

Have the same number of protons but a different number of neutrons

Question 3

Unit of specific charge

Answer 3

C/kg

Question 3

“specific” meaning

Answer 3

Amount of something per unit mass

Question 4

Specific charge (charge to mass ratio)

Answer 4

Charge / mass

Question 5

Do the electrons need to be included in specific charge calculations?

Answer 5

No, but it must be noted that their mass in negligable

Question 6

Use of specific charge

Answer 6

Identifying unknown particles

Question 7

Rest mass

Answer 7

The mass of an object when it is stationary

Question 8

Rest energy

Answer 8

The energy of an object when it is stationary (also called minimum energy)

Question 9

How is mass effected by an objects motion?

Answer 9

A moving object has greater KE, so it has a slightly greater mass

Question 10

Particles and Anti-particles

Answer 10

Every particle has a corresponding anti-particle. Both have the same mass, but opposite values for charge or some other important property.

Question 11

Annihilation

Answer 11

Occurs when a particle meets its own anti-particle. All the mass is converted to photons of energy - two photons moving in opposite directions must be created to conserve momentum.

Question 12

Pair production

Answer 12

One photon of sufficient energy may provide the mass to produce a particle-anti-particle pair.

Question 13

What is additional energy converted to in annihilation and pair production?

Answer 13

Kinetic energy

Question 14

Four fundamental forces

Answer 14

• Gravity
• Electromagnetic
• Strong nuclear force
• Weak nuclear force

Question 15

Electromagnetic force

Answer 15

Effects charged objects (responsible for most everyday forces)

Question 16

Strong nuclear force

Answer 16

Holds together nucleons as well as the quarks inside each proton and neutron.

Question 17

Weak nuclear force

Answer 17

Responcible for beta decay, effects hadrons, leptons and neutrinos (only force to effect neutrinos)

Question 18

Range where strong force is attractive

Answer 18

0.5fm to 3fm

Question 19

Range where strong force is repulsive

Answer 19

<0.5fm

Question 20

When does the strong force = 0?

Answer 20

> 3fm

Question 21

What prevents the nucleus from collapsing?

Answer 21

The strong force becomes repulsive when nucleons get too close

Question 22

Why is it clear that the strong force only acts over a very small range?

Answer 22

Different sized nuclei have the same density (no cumulative squashing effect as nucleons are only attracted to their immediate neighbors)

Question 23

What makes a nucleus unstable?

Answer 23

Having too many protons relative to the number of neutrons (there are not enough neutral particles to separate the protons and reduce the effect of the repulsion)

Question 24

Alpha particle

Answer 24

2 protons + 2 neutrons (helium nucleus)

Question 25

Two main categories of particle

Answer 25

Hadrons and leptons

Question 26

Two categories of hadrons

Answer 26

Baryons and mesons

Question 27

Which particles are baryons?

Answer 27

Protons and neutrons

Question 28

Which particles are measons?

Answer 28

π-mesons (pions) and k-mesons (kaons)

Question 29

Which particles are leptons?

Answer 29

Electrons, muons and their associated neutrinos

Question 30

What are hadrons made up of?

Answer 30

Quarks

Question 31

Baryon/Lepton number of a particle?

Answer 31

1= Is a baryon/lepton -1 = Is an anti-baryon/anti-lepton 0 = Not a baryon/lepton

Question 32

Which quantum numbers are conserved in interactions?

Answer 32

Charge Baryon number Lepton number

Question 33

Hadrons

Answer 33

The only particles which experience the strong nuclear force. Made of quarks and antiquarks. They are baryons or mesons.

Question 34

Baryons

Answer 34

Consist of 3 quarks (qqq). Anti-baryons consist of 3 antiquarks (q̅q̅q̅)

Question 35

Mesons

Answer 35

Consist of a quark and an antiquark (qq̅)

Question 36

Which particle is its own antiparticle?

Answer 36

Π⁰

Question 37

Which particle has the greatest specific charge?

Answer 37

Electrons

Question 38

What is the only stable baryon?

Answer 38

Protons (all other baryons will decay to protons eventuly)

Question 39

Quark structure of a proton

Answer 39

uud

Question 40

Quark structure of a neutron

Answer 40

udd

Question 41

Leptons

Answer 41

Leptons are fundamental particles - they are not made up of any simpler bits

Question 42

Muons

Answer 42

Same charge as an electron but is much heavier.

Question 43

What forces do leptons experience?

Answer 43

- Weak nuclear force - Electromagnetic force (charged particles)

Question 44

What forces do hadrons experiance?

Answer 44

- Strong nuclear force - Weak nuclear force - Electromagnetic force (charged particles)

Question 45

Where do a lot of neutrinos come from?

Answer 45

Nuclear reactions in the sun

Question 46

Strange particals

Answer 46

Created by the strong interaction, decay by the weak interaction. Contain strange quarks.

Question 47

When is strangeness conserved?

Answer 47

Conserved in the strong interaction Not conserved in the weak interaction

Question 48

How can the strangeness change?

Answer 48

By +1 or -1

Question 49

Exchange particles

Answer 49

Transfer energy, momentum, force, and sometimes charge between interacting particles

Question 50

Exchange particles for strong nuclear force **between hadrons**

Answer 50

Pi-measons

Question 51

Exchange particles for weak nuclear force

Answer 51

W+ and W- bosons

Question 52

Exchange particles for electromagnetic force

Answer 52

Photons

Question 53

Why are exchange particles virtual particles?

Answer 53

They only exist for a short time and can't be detected without interfering with their behavior.

Question 54

Vertical direction a Feynman diagram

Answer 54

Time

Question 55

Horizontal direction on a Feynman diagram

Answer 55

Space

Question 56

Why can't a particle move downwards on a Feynman diagram?

Answer 56

It would be moving backwards in time

Question 57

What interaction causes beta decay?

Answer 57

The weak interaction

Question 58

What is electron capture?

Answer 58

An unstable nucleus captures an orbiting electron turning a proton into a neutron and an electron neutrino to become more stable

Question 59

Why is an x-ray emitted after electron capture?

Answer 59

An electron moves down energy levels to fill the gap left by the electron involved in the interaction

Question 60

What is beta- decay?

Answer 60

A neuron turns into a proton, an electron and an anti-electron-neutino

Question 61

Evidence for the antineutrino in beta- decay

Answer 61

Beta particles are emitted with a range of energies. The same energy is given out in each decay but it is unevenly distributed between the products.

Question 62

What is a ß- particle?

Answer 62

High energy electron emitted from the nucleus

Question 63

What is a ß+ particle?

Answer 63

A high energy positron emitted from the nucleus

Question 64

What is beta+ decay?

Answer 64

Where a proton becomes a neutron, a positron and a neutrino

Question 65

What is an alpha partical?

Answer 65

A helium nucleus (2 protons + 2 neutrons)

Question 66

What are the 3 types of fundamental partical?

Answer 66

- Leptons - Bosons - Quarks

Question 68

Relative mass of an electron

Answer 68

0.0005

Question 69

What do kaons decay into?

Answer 69

Pions