Particles Flashcards
What is the force which overcomes the repulsive force within the nucleus ?
The strong nuclear force
What types of particles does the strong nuclear force impact ?
Hadrons ( neutrons and protons )
What is the purpose of the strong nuclear force ?
To overcome the repulsive electrostatic forces holding the nucleus together
At what distances is the strong nuclear force repulsive ?
Under 0.5 fm
What is the range of the strong nuclear force ?
3-4 fm (10^-15)
Why is the strong nuclear force repulsive at certain distances ?
To prevent the protons and neutrons from colliding into each other
Why does alpha decay occur ?
The atom is too large for the strong nuclear force to keep stable
What is an alpha particle ?
A helium nucleus consisting the nucleon number 4 and proton number 2
What happens to the nucleon number as the particle undergoes alpha decay ?
Decreases by 4
What happens to the proton number as the particle undergoes alpha decay ?
Decreases by 2
What is the range of an alpha particle ?
A few centimetres (short range )
Why does beta minus occur ?
Due to the high ratio of neutrons to protons , converting a neutron to a proton
What is ionisation ?
The removal or addition of electrons from an atom or molecule
Which beta decay converts a neutron to a proton ?
Beta minus decay
What does a beta minus decay emit ?
A beta particle along with an antineutrino
What happens to the the nucleon number during the emission of a beta particle ?
The nucleon number remains the same
What happens to the proton number as a beta minus particle is emitted ?
The proton number increases by one
Explain why alpha dust is hazardous to an unprotected human
- can enter the body through ingesting or breathing in the particles which can kill cells as the human cells and tissues become damaged
How had neutrinos been discovered ?
- the energy after the decay had been lower than the initial energy (not following the conservation of energy principle )
This lead to the suggestion that another particle is also emitted with almost no mass and charge
What is a gamma radiation ?
An electromagnetic radiation emitted by an unstable nucleus
Why is gamma radiated ?
Particles with too much energy following an alpha or a beta emission
What does every particle have ?
An antiparticle with the same mass and rest energy but an apposite charge
Why does annihilation occur ?
When a particle comes into contact with its antiparticle
What occurs when a particle is annihilated?
The mass is converted into energy producing two photons in opposite directions
Why are 2 photons produced in opposite directions when a particle and an antiparticle come into contact ?
To conserve momentum
What is the minimum energy of a single photon produced during annihilation ?
hfmin
What is the minimum energy produced during annihilation ?
The rest energy of the particle and its antiparticle combined
What is pair production ?
When a discrete photon creates a particle and its corresponding antiparticle
What is the minimum energy of the photon required for pair production to occur ?
The sum of the rest energy of the particle and its corresponding antiparticle
What are photons ?
Packets of electromagnetic waves
What is the electromagnetic spectrum ?
Radio , micro, infrared, visible, ultraviolet, X-rays, gamma rays
Why must the frequency be a certain value for pair production to occur ?
If the frequency is below a certain value there is not enough energy to provide the rest energy of the particle and its antiparticle as e is directly proportional to f
What speed do electromagnetic waves travel in a vacuum?
3 *10^8 m/s
What has a greater wavelength gamma or radio ?
Radio has a greater wavelength
What has a greater frequency gamma or radio waves ?
Gamma has a greater frequency
What is the energy of a photon equal to ?
Planks constant * frequency or (speed/ wavelength)
Properties that are conserved in pair production ?
Energy, momentum , charge , lepton , baryon , strangeness
What is planks constant ?
6.63*10^-34
What are forces a result of ?
Particle exchange
Why do two like charges repel each other ?
One of the particle passes an exchange particle to the other transferring momentum, resulting in them moving away from each other ( a guy throwing a ball on a skateboard)
What do oppositely charged particles attract each other ?
One of the particle passes an exchange particle to the other particle transferring momentum resulting in the particles moving towards each other
What is the exchange particle of the electromagnetic force ?
Virtual photon
What particles are affected by the electromagnetic force ?
All charged particles
What force is responsible for the repulsion of two like charges ?
The electromagnetic force
What is the exchange particle of the weak force ?
W+ and w- and z0 bosons
What force is affects by all particles?
Weak force
What force and exchange particle is responsible for the emission of beta plus and minus particles ?
Weak - w bosons
What is produced when a neutron and neutrino interact ?
A proton and a beta minus is emitted
What is produced when proton and antineutrino interact?
A beta plus and a neutron is emitted
Which interaction emits a neutron and a beta plus particle ?
- proton and an antineutrino
What interaction produces a proton and a beta minus particle ?
Neutrino and a neutron
What is the bosson when a beta minus particle is an antineutrino is emitted ?
W -
What is the bosson when a beta plus particle is a neutrino is emitted ?
W + bosson
What are the two classifications of particles ?
Hadrons and leptons
What are hadrons ?
Particles made up of quarks that experience the strong nuclear force
What can hadrons be further classified as ?
Baryons and mesons
What is the difference between baryons and mesons ?
Baryons are made up three quarks whereas mesons are made from two a quark and an antiquark
What are baryons ?
Protons and neutrons ( they all decay to become other particles ,always including a proton within the decay as a proton is the most stable
What is the baryon number of a proton ?
1
What type of number is the baryon number ?
A quantum number
What reaction is the baryon number conserved in ?
All interactions
What are mesons ?
Pions , kaons
What is a pion ?
The lightest mesons
What is a kaon ?
A heavier more unstable meson which have a short life time and decay into pions
What is a lepton ?
Electron and muons
What is a muon ?
A heavier more unstable version of an electron therefore it decays into an electron
What type of interactions do neutrinos take part in ?
W bozzons
What are lepton rules ?
-leptons can convert into other leptons as well as be produced or ambulated within a particle antiparticle interaction
