Particle Physics

Question 1

List the four fundamental forces from weakest to strongest.

Answer 1

• Gravitational
• Electromagnetic
• Weak Nuclear
• Strong Nuclear

Question 2

List the range, affects, purpose and magnitude of gravitational force.

Answer 2

R - Infinite
A - All particles
P - Attracts all matter
M - 10-³⁸

Question 3

List the range, affects, purpose and magnitude of electromagnetic force.

Answer 3

R - Infinite
A - Charged particles
P - Atomic bonding
M - 10-²

Question 4

List the range, affects, purpose and magnitude of weak nuclear force.

Answer 4

R - 10-¹⁸m
A - All particles
P - Beta decay
M - 10-⁷

Question 5

List the range, affects, purpose and magnitude of strong nuclear force

Answer 5

R - 10-¹⁵m
A - Nuclear material (eg protons, neutrons)
P - Binds nucleus
M - 1

Question 6

What is the Grand Unified Theory (GUT)?

Answer 6

The GUT merges electromagnetic, weak nuclear and strong nuclear forces into one law of interaction.

Question 7

What is the Theory of Everthing?

Answer 7

It integrates the gravitational force with the three other forces.

Question 8

What are the conservation laws?

Answer 8

• Conservation of mass/energy
• Conservation of momentum
• Conservation of charge

Question 9

What is the Cockcroft and Walton experiment?

Answer 9

It is the first transmutation using artificially accelerated particles. This was done in a linear accelerator.

Question 10

Describe Cockcroft and Walton’s experiment.

Answer 10

• A hydrogen-discharge tube produces protons (hydrogen nuclei) which are introduced into the column.
• A decreasing high voltage supply of 400kV-0V accelerate the protons towards the bottom of the tube.
• The proton strikes a lithium target at 45° to the proton beam.
• This produces two alpha particles (helium nuclei) moving 180° apart, left and right of the plate.
• The alpha particles strike a zinc sulphide screen, which causes scintillations.
• Each flash is observed by looking through a microscope on either side of the target.

Question 11

State the relevance of the Cockroft and Walton experiment.

Answer 11

• First particle accelerator
• First artificial splitting of an atom
• First transmutation of an atom
• Verification of E=mc²

Question 12

What is the equation produced from the Cockcroft and Walton experiment?

Answer 12

Li + H = He + He + EK

Question 13

What is a proton proton collision equation?

Answer 13

p + p + Q1 = p + p + additional particles + Q2

Question 14

What was the solution to missing momentum?

Answer 14

Neutrino

Question 15

What are the benefits of circular accelerators over linear accelerators?

Answer 15

Higher speeds can be reached, therefore there is more kinetic energy, thus more new particles can be created

Question 16

What is antimatter?

Answer 16

Antimatter is matter composed of antiparticles. Antimatter has identical mass but opposite charge and quantum spin to the original particle

Question 17

What is pair production?

Answer 17

The simultaneous creation of a particle and its antiparticle from electromagnetic energy

Question 18

State an equation for pair production.

Answer 18

Y = e- + e+ + EK + v(neutrino)

Question 19

What is pair annihilation?

Answer 19

The conversion of a particle and its corresponding antiparticle into electromagnetic energy

Question 20

State an equation for pair annihilation.

Answer 20

e- + e+ + EK= 2Y + v(neutrino)

Question 21

What is the particle zoo?

Answer 21

The zoo divides particles accordingly to which fundamental force affects them, their size and other characteristics to do with magnetic and quantum spin

Question 22

What is a quark?

Answer 22

An elementary particle which experiences all four fundamental forces and forms a basic constituent of matter

Question 23

What are the six flavours of quark?

Answer 23

Up, down, top, bottom, charm, strange

Question 24

What are leptons?

Answer 24

Leptons include all fundamental particles which are not subject to the strong nuclear force but are affected by the others. eg electron, muon, tau

Question 25

What are hadrons?

Answer 25

Hadrons are particles that feel all four forces. They are split into baryons and mesons

Question 26

What are baryons?

Answer 26

Particles composed of 3 quarks or antiquarks. They have a mass greater than or equal to that of a proton. eg proton, neutron, lambda, sigma

Question 27

What are mesons?

Answer 27

Particles composed of a quark and antiquark. They are between the size of an electron and proton. eg pion, kaon

Question 28

What is the quark composition of a proton and a neutron?

Answer 28

Proton = uud
Neutron = udd