Particles P01-07 Flashcards
What does the basic structure of an atom look like?
Protons and neutrons within the nucleus, with electrons in the orbit around the nucleus of the atom.
What is a nucleon?
A particle in the nucleus, so therefore a neutron or a proton.
What is a nuclide?
A nucleus with specific number of protons and neutrons.
What is nuclide notation?
Symbol with a number above and below it.
Mass number above it and the atomic number below it.
Define specific charge.
The specific charge of a particle is the ratio of its charge per unit mass.
How can isotopic data be used within archaeology?
Carbon dating, the amount of radioactive carbon-14 in things decays once it dies, therefore less means older.
How can isotopic data be used within forensic?
From drinking water that has natural isotopes, by using a person’s hair you can see their DNA.
What’s the range for the strong nuclear forces?
At less than 0.5fm the force is repulsive. Between 0.5-3fm the force is attractive. Beyond 3fm the force is 0.
what does a graph of force vs distance for the strong nuclear force look like.
An L shape that curves up to 0 after the bottom of the L shape hits around 0.8fm on the distance axis.
What is an alpha particle?
A helium nucleus emitted by some radioactive substances, originally regarded as a ray. The mass number goes down by 4. The atomic number goes down by 2. Large nuclei.
What is a beta particle?
A high speed/energy electron or positron emitted by the radioactive decay of a nucleus, beta +/-. As a result of too many neutrons.
Why did Pauli propose the existence of the neutrino?
Pauli suggested that if a non-interacting, neutral particle (a neutrino) were emitted, one could recover the conservation laws. To conserve angular and energy momentum.
List the types of e-m radiation in order:
i) Which has the longest/shortest wavelength?
ii) Which has the highest/lowest energy?
i) Radio, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays.
ii) Reverse order than the one above.
Show how to convert from eV into joules.
1 eV = 1.602 x 10^-19 J
Show how to convert from joules into eV.
J / ev (1.602 x 10^-19) = # eV.
What property is the same for both matter and antimatter particles?
The mass and magnitude of its electric charge.
Describe the process of annihilation.
A particle and its equivalent antiparticle are both destroyed and their mass is converted into energy in the form of two gamma ray photons. To conserve momentum, the two photons will move apart in opposite directions. As with all collisions, the mass and energy is still conserved.
Describe the process of pair production from a photon.
Pair production is when one high energy photon spontaneously turns into a particle - antiparticle pair. The energy of the photon must be at least the total past mass energy of the particle - antiparticle creates.
Describe the process of pair production by collision.
When a photon interacts with a nucleus or atom and the energy of the photon is used to create a particle–antiparticle pair.This means the energy of the photon must be above a certain value to provide the total rest mass energy of the particle–antiparticle pair. The minimum energy for a photon to undergo pair production is the total rest mass energy of the particles produced:
Emin = hfmin = 2E
How do we differentiate between hadrons and leptons?
Hadrons feel the strong and weak nuclear force and are composed of quarks. Leptons are light particles with no structure and feel only the weak nuclear force.
How do we differentiate between baryons and mesons?
These are hadrons. Baryons consist of 3 quarks, mesons have a quark and an anti-quark.
Which quantities are always conserved in particle processes?
Energy, momentum, bayron number and charge.
When might strangeness not be conserved?
It is conserved in strong interactions and electromagnetic interactions but not in weak interactions.
State the quark composition of a proton and neutron.
Proton = uud. Neutron = udd.
State the quark composition of the pi-mesons: π+;
π+: ud^-
State the quark composition of the pi-mesons: π0;
π0: d u/d^-
State the quark composition of the pi-mesons: π-;
π-: du^-
State the quark composition of the K-mesons:
K⁺;
K⁺: us^-
State the quark composition of the K-mesons:
K⁰;
K⁰: ds^-
State the quark composition of the K-mesons:
K⁰;
K⁰; d^-s
State the quark composition of the K-mesons:
K⁻;
K⁻: u^-s
Write down the equation for the beta decay of a proton:
Including charge, baryon number and leptons.
n = p + e^- + ve^-
Q: 0= 1 - 1 + 0
B: 1 = 1 + 0 + 0
Le: 0 = 0 + 1 - 1
Write down the equation for the beta decay of a neutron:
Including charge, baryon number and leptons.
p = n + e^+ + ve
Q: 1 = 0 + 1 + 0
B: 1 = 1 + 1 - 1
Le: 0 = 0 - 1 + 1
Write down the equation for muon decay (both μ- and μ+).
u^- = e^- + ve^- + vu
u^+ = e^+ + ve + vu^-
What are the exchange particles for the e-m, strong and weak interactions?
Weak interactions - W+, W- bosons.
EM interaction is the photon.
Strong interactions is the gluon
Gravity is the graviton.
What is electron capture?
Electron capture is an example of a weak interaction where an electron is absorbed by a proton within a nucleus. The proton decays into a neutron and a W+ exchange particle interacts with the electron forming an electron neutrino.
Diagrams for particle interactions:
β- decay
Nucleus to a proton, with a W^- boson and an electron and an electro neutrino.
Diagrams for particle interactions:
β+ decay
Proton to a nucleus, with a W^+ boson and an positron and an electro neutrino.
Diagrams for particle interactions:
electron capture
Proton and electron collision and a neutron off of the proton and a anti neutrino off of the electron.
W^+ boson from left to right, proton to electron side.
Diagrams for particle interactions:
electron-proton collision
Proton and electron collision and a neutron off of the proton and a anti neutrino off of the electron.
W^- boson from right to left, proton to electron side.
How does a PET scanner work?
Positron emitting isotope is put into a patient’s bloodstream. The positron meets and annihilates with an electron producing gamma photons that are then detected.
What does strangeness mean?
Describes the decaying of particles in strong and electromagnetic interactions which occur in a short period of time.
What are cosmic rays made up of?
90% protons
10% alpha particles
What force is used to differentiate between leptons and hadrons?
Hadrons can feel the strong force, while leptons can’t.
Due to cosmic rays what does a Muon decay to?
Electrons
Due to cosmic rays what does a Pion decay to?
Muons
Due to cosmic rays what does a Kaon decay to?
Pions
What does a Kaon, Pion, Muon all have in common?
All lighter than a proton.
