Section 1 Particles and Radiation Flashcards
What is the mass (in kg) of the nucleons?
1.67x10‐²⁷ kg
What is the mass (in kg) of the Electron?
9.11x10‐³¹ kg
What is the value (in Coulombs) of 1e - the relative charge?
±1.6x10‐¹⁹
What is specific charge?
It’s the ratio of a particles charge to its mass, therefore charge÷mass
What is an isotope?
An element with the same number of protons and electrons, but a different number of neutrons.
What forces are acting on the nucleus?
Electromagnetic force between the protons causing them to repell.
Gravitational force holding the particles together (kind of)
The strong nuclear force
What is the strong nuclear force?
An attractive force that holding the nucleons together
What are the properties of the strong nuclear force?
Acts on a small range of a few femtometres
It is attractive to nucleons up to 3fm away
It is repulsive to nucleons closer than 0.5fm away so that the nucleus does not collapse
What is an alpha particle?
Helium nucleus- 2 protons 2 neutrons
How do the proton and nuleon number change druing alpha decay?
Proton number decreases by 2
Neucleon number decreases by 4
Bigger atoms are more likely to experience _____ decay
Neutrons rich atoms are more likely to experience _____decay
Big- alpha
Neutrons rich- beta minus
What is a beta particle?
A high energy electron
What happens during beta minus decay?
A high energy Electron gets ejected by the nucleus, along with an Electron antineutrino which accounts for the loss of energy during beta decay
A neutron turns into a proton.
How do the nucleon and proton number change during beta minus radiation?
Proton number increases by 1
Nucleon number stays the same
Which scientist hypothesised the antineutrino?
Wolfgang Pauli
What are photons?
‘Wave packets’ that are carriers of energy
How do you figure out the energy of a photon?
E=hf=hc/wavelength
What is pair production and how does it occur?
Pair production is the process of turning energy into mass, this happens when two particles collide with enough energy that they produce equal amounts of matter and antimatter
Photons- given they have enough energy- will also produce an Electron positron pair usually when it’s near a nucleus
What is annihilation?
When a particle meets it’s antiparticle
The mass of both get converted back to energy un the form of 2 gamma ray protons
What are Hadrons?
Particles affected by the strong force
What are Baryons?
Non fundamental particles made from 3 quarks with a baryon number of +1
eg protons, neutrons, others like sigmas
What are Mesons?
Particles made from a quark/anti quark pair with a Baryon number of 0.
eg pions, kaons, and other mesons.
What is neutron decay?
When beta decay occurs, a neutron becomes a proton due to the WEAK INTEREACTION, when the nucleus is too neutron rich. A neutron turns into a proton, Electron and antineutrino.
What are the 5 things that must be conserved during any interaction?
Energy
Momentum
Charge
Lepton number
Boson number
What is Electron capture?
proton rich nuclei steal inner electrons using the weak intereaction
What is the minimum energy required for pair production?
The minimum energy required for this is Emin=2E⁰
What particles are affected by the strong force?
Hadrons only
What is the gauge boson for the strong force?
Pions/Gluons
What particles are affected by the electromagnetic force?
Charged particles only
What are the gauge bosons for the electromagnetic force?
Photons
What particles are affected by the weak force?
All types
What is the gauge boson for the weak interaction?
W+ and W- bosons
What is a use of isotopic data?
The use of measuring the % of Carbon 14 left in a fossil.
All living things have the same Carbon 12 and 14 ratio, Carbon 14 decays.
Can be used to date fossils
What is the definition of an antiparticle?
A particle with the same mass, but opposite characteristics to a corresponding particle.
What is the photoelectric effect?
The photoelectric effect is the emission of electrons from a material when it is exposed to light or electromagnetic radiation.
Fill in the blank: The minimum frequency of light required to cause the photoelectric effect is called the __________.
threshold frequency
In what type of interaction is strangeness conserved, why?
In the strong interaction, because only the weak interaction can change quark structure therefore change strangeness
Strangeness can only change by __ in a weak interaction.
1
What is the maximum kinetic energy of a photoelectron proportional to?
The frequency of the radiation
