Side A - Particles and Radiation

Define an isotope

An atom of the same element with the same number of protons but a different number of neutrons

What are the 2 types of fundamental particle

Quarks and Leptons

What are quarks types

Up (u) + Down (d)

strange (s)

What is the proton number

Number of protons in nucleus of an atom

Can be called atomic number

Smallest number of an element

Also equal to No. of electrons atom has

What is the nucleon number

Number of protons in an atom + number of neutrons in an atom in atoms nucleus

Also called mass number

What is specific charge

= charge of particle/mass of particle

Measured in coulombs per kg (Ckg-1)

The greater the charge the greater the force

The greater the mass the less the force accelerates particles

Charge of a proton

1.60×10^-19 C

Charge of electron

-1.60×10^-19 C

Charge of neutron

0 charge

Define strong nuclear force

is attractive between 0.5-3.0fm (atom becomes unstable if not in range)

is repulsive below 0.5f

hold protons and neutrons together

Exchanged through pion

Define weak nuclear force

Exchanged by W bosons

Used in beta+ (proton-neutron) and beta- decay (neutron-proton)

affects unstable nuclei

Define electromagnetic force

Exchanged by virtual photon

Used in gamma radiation

What is Alpha radiation

Occurring in large nuclei

Alpha particle is a helium atom

Proton No. decrease by 2

Nucleon No. decrease by 4

What is Beta radiation

Occurs in nuclei with too many neutrons

Beta particle is a fast moving electron

Proton No. increases by 1

Neutron decays into proton + electron + electron antineutrino

What is gamma radiation

EM radiation emitted from unstable nucleus

Occurs after alpha or beta decay, as nucleus has excess energy

What is EM radiation

Emitted when charged particles loose energy

Consists of electric and magnetic field waves which are at right angles to each other

What is the wave equation

Wave speed (c)(3.00×10^8 ms-1) = frequency (f -Hz)/ Wavelength (λ - m)

What is a photon

A discrete packet of waves

each photon carries energy that relates to its frequency (the higher the frequency the more energy)

EM force exchange particle, emitted when a charged particle looses energy

Photon energy equation

Photon energy (E) = Planks constant (6.63×10^-34 Js) x Frequency (f - Hz)

E = h x c/λ

Define antimatter and its components

All particles have corresponding antimatter

They have same mass but opposite charge (if particle is charged)

If they collide with corresponding particle annihilation occurs

If photon directed at them, pair production occurs

e.g. antiproton, positron, antineutrino

Define Annihilation

particle and corresponding antiparticle colliding

Mass and kinetic energy converted to 2 gamma photons with the same frequency

They move off in opposite directions

They conserve momentum

Define pair production

photon is directed at nucleus or electron

corresponding particle and antiparticle pair produces

photon must have minimum freq and energy

MeV to Joules

1MeV = 1.60×10^-13J

Min energy of photon

E = hf = hc/λ

E - energy

h - planks constant

f - frequency

λ - wavelength

c - speed

Particle interactions

like charges repel

opposite charges attract

e.g. EM force between protons - photon transfers momentum so protons repel

W boson characteristics

have non-0 rest mass

short range (0.001fm)

can be positive or negative

B- decay

Neutron becomes proton

W- becomes B- (e-) and electron anti-neutrino

in neutron rich nucleus

B+ decay

Proton becomes neutron

W+ becomes B+ (e+) and electron neutrino

in proton rich nucleus

Electron capture

proton in proton rich nucleus turning to neutron when interacting with inner-shell electron with weak interaction

proton becomes neutron

W+ boson makes e- into ve

What is a muon

heavy electron - μ

type of lepton

negatively charged

higher rest mass than electron - decays into electron+antineutrino/positron+neutrino

What is a pion

π meson

positive or negative or neutral charge

heavier rest mass than muon - decays into muon+antineutrino/antimuon+neutrino if charged, if not charged decays into high energy photons

What is a Kaon

K meson

positive or negative or neutral charge

rest mass larger than pion - decays into pions/muon+antineutrino/antimuon+neutrino

have a strangeness

formed through strong interaction, decay through weak interaction

What is a hadron

particles and antiparticles that interact through strong interaction

e.g. proton, neutron, pion, kaon

made up of quarks

What is a lepton

fundamental particle

interacts though all interactions but strong interaction

e.g. muons, electrons, neutrinos

leptons + antileptons can interact to produce hadrons

Undergoing weak interaction leptons change into other leptons

Lepton No. must be conserved in interactions

Rest energy equation

rest energy = total energy before - kinetic energy of products

What is a baryon

Hadron made up of 3 quarks/antiquarks

Decay into protons

e.g. protons and neutrons

What is a Meson

Hardon made up of quark antiquark combination

Dont decay into protons

e.g. kaons and pions

Neutrinos

Travel near light speed

Travel whilst interacting very little with other particles

each non-neutrino lepton has a neutrino and antineutrino

e.g. muon neutrino and electron neutrino

Produced in decay

Strangeness

from strange quarks

can be conserved by + or - one in weak interaction

Meson combinations

Bottom and top row kaons with strangeness

Pions have no s

Baryon combinations

Proton - uud

neutron - udd

what is conserved in particle interactions

1. Energy (including rest energy) and charge- all interaction

2. Lepton No. - all interaction

3. strangeness - in strong interaction

4. Baryon No. - all interaction

Photoelectric effect

Electrons emitting from surface of metal when EM radiation above threshold frequency is directed at said metal

No. of electron emitted is proportional of incident ray intensity, if freq is above threshold

Each electron at surface gains energy from waves no matter how many waves arrive each second

Proves that light can also be particle (wave-particle duality)

Threshold frequency

min freq for photoelectric effect to take place

changes depending on metal

Photoelectric effect explanation

When light meets surface of metal, each electron absorbs single photon and gains energy of hf

If energy gained is more than work function (ϕ) an electron can leave the metal surface

Any excess energy gained by photoelectron is converted to Ek

Work Function

Min energy electron needs to gain to escape metal surface

Max Ek of electron emitted in photoelectric effect equation

Ek(max) = hf - ϕ

Threshold freq equation

f (min) = ϕ/h

Stopping potential

Min energy needed to stop photoelectric emission, where Ek(max) of emitted electron becomes 0, so each electron has to do extra work to leave metal surface

Ek(max = e x Vs (stopping potential)