Particles Flashcards
What is specific charge?
Charge/Mass
Charge per Unit mass
What is a nucleon
particle that is constituent of a nucleus
Proton or neutron
What is an isotope?
Variants of the same element with the same amount of protons but different masses and number of neutrons
State a use of radioactive isotopes
Carbon Dating
Working out the proportion of carbon 14 within a material
Can be used as an age estimate
What is a. strong nuclear force?
A Fundamental force that keeps the nucleus bonded and stable
by counteracting electrostatic force of repulsion between protons under 3fm of distance
Binding nuelons together
Stopping the implosion of the atom by acting as a repulsive force below 0.5 femto meters
Describe the range of the strong force
Past 3 fm it is repulsive (very slightly)
What makes a nucleus unstable
a nuclei with too many protons or neutrons or too much energy
How do nuclei with too many nucleons decay?
Alpha decay (Mass No 4 Atomic No 2)
How do nuclei with too many neutrons decay (3)
Beta minus decay
neutron decays into a proton via the weak interaction
Quark has changed from Udd—> UUd
How was the existence of the neutrino hypothesised?
Net Energy of particles after beta decay had decreased after the reaction
Therefore a particle with neutral charge and negligible mass was hypothesised to carry away the excess energy
What is meant by beta minus decay? (3)
When a neutral turns into a proton
The atom releases an electron and anti neutrino
Down quark changes to an upquark
What is an anti particle
For each particle there is a anti particle
Same rest energy and mass
opposite in charge and other qualities
What is the anti particle of a neutral pion
A neutral pion (itself)
Describe what occurs when a particle and its anti particle meet?
Annihilation
When a particle and its antiparticle collide
Total Rest energy and kinetic energy is converted two 2 gamma photons
Emitted in opposite directions to conserve momentum
What is pair production
when a gamma ray photon of enough energy is converted into a particle-antiparticle pair each with identical kinetic energy.
Name the 4 fundamental forces
Gravitational
Electromagnetic
Weak Nuclear
Strong Nuclear
What is the exchange particle for the electromagnetic force
Virtual photon
What particles are effected by the strong nuclear force
Hadrons
What is the exchange particle for the weak nuclear force
The W Boson
W+ or W-
What does the electromagnetic force act on
Charged objects
When does the weak interaction occur
When a quark changes character/flavour
eg. u——> d
What properties must be conserved in all particle interactions (5)
Momentum
Energy
Brayon number
lepton number
Charge
What property isn’t conserved in the weak interaction
Strangeness
What is a hadron
Particles made of 2 or more quarks and are held together by the strong nuclear force
What are the classes of hadrons
Baryons - 3 quarks
Mesons ( 1 quark and an anti quark)
What is the exchange particle of the strong force
pion
What is a significant about a proton
Only stable baryon
All baryons eventually decay into protons
1) what does a muon decay into
2) what does an anti muon decay into
In what interaction?
1) electron and anti neutrino
2) Positron and neutrino
Weak
What does a Negative, positive an neutral pions decay into?
What interaction?
1) muon + antineutrino
2) anti muon + neutrino
3) 2 Photons
Strong creation decay weak
What does a neutral, negative and positive kaon decay into (3 types for negative and positive
What interaction
Neutral = 2 pions (either + & - or 2 neutral)
Negative = Muon + anti muon neutrino
Or negative pion + neutral pion
Or neutral pion + muon + anti muon neutrino
positive = Anti Muon + muon neutrino
Or positive pion + neutral pion
Or positive pion + positive pion + negative pion
Strong creation , weak decay
What is the strangeness value for a strange quark
-1
Strange particles are produced through the ______________ and decay through the ____________
1) strong
2) weak
