3.2 Particles and radiation Flashcards
what is the proton and nucleon number and and their symbols
Nucleon number is the total amount of protons and electrons(A)
Proton number(Z)
altogether this is called nuclide notation
define an isotope
each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, hence differ in relative atomic mass but not in chemical properties
what is specific charge
specific charge, also referred to as charge to mass ratio charge/mass in kg C*-1
what is a strong nuclear force and its role
a strong nuclear force is the opposing force against electrostatic forces which keeps protons and neutrons together
describe the effect of a strong nuclear force and how it works
The strong nuclear force is repulsive below 0.5 fm, and attractive up to 3 fm, before approaching zero no effect at large separations.
what is a neutrino
A neutrino is a subatomic particle that is very similar to an electron, but has no electrical charge and a very small mass, which might even be zero.
an uncharged lepton with very low rest mass compared with the electron
what is the exchange particle in beta minus decay
w - boson for beta minus
w + boson for beta plus decay
exchange particles are essentially there to let the other particle know there is another particle is there - must be there for repulsion to occur
why was the existence of the neutrino discovered
The existence of the neutrino was hypothesised to account for conservation of energy in beta decay.
beta minus and plus decays
beta minus - neutron decay into proton (w-)
beta plus - proton decay into neutron (w+)
what is annihilation
When a particle meets its equivalent anti–particle they both are destroyed and their mass is converted into energy in the form of two gamma ray photons - the photons are to conserve momentum
Pair production is
When a photon interacts with a nucleus or atom and the energy of the photon is used to create a particle–antiparticle pair
which exchange particles are used for the weak interaction and which exchange particle is used for the electromagnetic interaction
weak interaction uses w bosons whereas the electromagnetic interaction(eg em repulsion) uses photons
describe pair production
In pair production a photon creates a particle antiparticle pair since the energy gets converted into matter and anti matter in the form of a photon
the minimum energy of a photon to undergo pair production is the total rest energy of the particles produced
What is 1 fm in m?
10⁻¹⁵ m
How strong is the weak force?
1 millionth(1/100000) the value of the strong force
What happens if the nucleus is still unstable after emitting alpha or beta radiation?
It is in an excited state, and gives off gamma radiation
What does an electromagnetic wave consist of?
An electric wave and a magnetic wave which travel together in phase
How do photons travel?
In one direction only in a straight line
electron capture equation
P + -e —-> n + electron neutrino
(w+ boson is the exchange particle
which interaction effects which particles and what is the exchange particles(guage bosons)
EM - virtual photon and effects only charged particles
Weak - W+/- and effects all particles eg electron capture/electron proton collisions
strong - pions(gluons) π+/-/0 and only effects hadrons
What are hadrons?
Particles that feel the strong nuclear force. They are not fundamental since theyre made up of quarks
What is a virtual particle?
Particles which exist for only a very short time and cannot be detected.
What is the difference between the 2 hadrons (baryons and mesons?)
- Baryons - Made of 3 quarks and decay into a proton directly or indirectly
- Mesons - Made of a quark and antiquark and do not decay into a proton
What is the only stable baryon?
Proton - this means all baryons will decay in sequence and eventually form a proton.
what are leptons and examples
fundamental particles that dont feel the strong nuclear force and only interact with other particles via weak interactions, they arent stable
Eg: electron , electron neutrino , muon and muon neutrinos , tau
muons are
leptons around 200x heavier than electrons so are unstable and will eventually decay into an electron
what is strangeness
like baryon number its a quantum number so it can only take a certain set of values
strange particles eg kaons are created via the strong interaction but decay via the weak interaction
strangeness is conserved in the strong interaction but is not conserved in the weak interaction
so strange particles are always produced in pairs eg k+ and k-
a weak interaction is
something which changes the quark type eg proton into neutron changes uud into udd
what are the 4 conserved properties in particle interactions
charge , baryon numbers , strangeness(only in strong interactions)
lepton numbers are conserved differrently, electron lepton number and muon lepton number is conserved
decay of a neutron equation
n —> p + e- + anti electron neutrino
which mesons are strange
kaons
how are particles discovered
- New theories created to explain observations from experiments , hypothesising a particle and properties they expect it to have
- experiments are carried out to find the existence of the particle and if the experiments confirm the theories and the scientific community accept it its validated
- but particle physics experiments often need particle accelerators which are expensive to build and run and many scientists would need to collaborate to fund them
how to convert from MEV into joules
x 1.6 x10*-13
what is electron capture
an electron interacting with a proton in the nucleus (via weak interaction) to form a neutron by changing the u into d quark and a neutrino released
in the interaction between protons in the nucleus what is it called and what is the exchange particle
electromagnetism
uses photons as the exchange particle
what is the exchange particle for the strong nuclear force
the gluon
decay of a kaon :
?
what are the strange particles and give examples and properties of them
??
pions ect and properties
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