Particles and Waves: 1 - The Standard Model and 2 - Forces on Charged Particles Flashcards
What is the standard model?
The Standard Model is a model of fundamental particles and interactions.
Where does the evidence for the existence of quarks come from?
The evidence for the existence of quarks comes from high-energy collisions between electrons and nucleons, carried out in particle accelerators.
What is a nucleon?
A proton or a neutron.
What are hadrons?
Composite particles that are made up of quarks.
How many types of hadron are there and what are they called?
- Baryons and Mesons.
What are baryons?
Baryons are like protons and neutrons and are made up of 3 quarks.
What are Mesons made up of?
Mesons are made up of quark - antiquark pairs so they are very unstable, e.g. a pion (π+) is made of an up quark and a down anti - quark.
What are examples of Mesons?
A pion (π+).
What are examples of Baryons?
Protons and Neutrons.
Are Mesons unstable?
Yes they are very unstable.
What are protons made of?
2 up and 1 down quarks.
What are neutrons made of?
2 down and 1 up quarks.
What is this (π+) pion made of?
1 up and 1 down anti - quark.
What are leptons?
Leptons are the fundamental particles, i.e. they can’t be split into anything smaller.
What are the 1st generation leptons?
The electron.
What are the 2nd generation leptons?
The muon.
What are the 3rd generation leptons?
The tau.
What do all leptons have in common?
They are negatively charged.
What is the charge of a neutrino and what does this mean for the neutrino?
Neutrinos have no charge,because of this they never interact with any other particles.
How were neutrinos initially discovered?
Neutrinos were initially discovered in radioactive beta decay experiments.
In beta decay what does a neutron decay into, why must another particle be admitted and what is the other particle that is admitted.
In beta decay, a neutron decays into a proton and an electron. In order for mass charge and energy to be conserved another particle must be admitted. This particle is the neutrino.
What is the equation of the beta decay of a neutron?
A neutron
->
proton + electron + neutrino
What are facts about the Strong (nuclear) Force?
- Electrostatic theory predicts that the protons in the nucleus should fly apart. This does not happen so there must be another force and holds the nucleons together.
- Extremely short range force that holds particle of the same charge together - holds quarks together to form hadrons. (HOLDS TOGETHER PARTICLES IN THE NUCLEUS)
What is the exchange particle/force carrier for the strong (nuclear force)?
The gluon because they glue particles together.
What are facts about the weak (Nuclear) force?
- Involved in radioactive beta decay.
- Extremely short range force.
- Is weaker than the strong nuclear force (hence its name).
- Experienced in quark and lepton interactions.
- ASSOCIATED WITH RADIOACTIVE BETA DECAY
What is the exchange particle/force carrier of the weak (nuclear) force?
The W and Z bosons.
What are facts about the electromagnetic force?
- Combination of electrostatic and magnetic forces.
- Has infinite range
- ACTS BETWEEN CHARGES
What is the exchange particle/force carrier of the electromagnetic force?
The photon.
What are facts about the gravitational force?
- Has infinite range
- Weakest of the 4 fundamental forces
- ACTS BETWEEN MASSES - requires large masses to produce significant forces.
What is the exchange particle/force carrier for the gravitational force?
The graviton
What do fermions consist of?
Fermions, the matter particles, consist of quarks (six types: up, down, strange, charm, top, bottom) and leptons (electron, muon and tau, together with their
neutrinos).
In the standard model what does each particle have and what is evidence for this?
In the Standard Model, every particle has an antiparticle and the production of energy in the annihilation of particles is evidence for the existence of antimatter.
What is a force field?
A region where an object experiences a force without being touched.
What are types of force fields?
Magnetic fields, gravitational fields and electrical fields.
What will a charged particle experience in an electrical field?
A force.
What will a uncharged particle like a neutron experience in an electrical field?
Nothing it will just continue with the path it starts with.
What do closer field lines mean in an electrical field?
A stronger force.
Where do the field lines start and finish in an electrical field?
From the positive charge to the negative charge.
In a positively charged particle where do the lines go?
Out the way.
In a negatively charged particle where do the lines go?
In the way.
When 2 positive charges meet what happens to the lines?
They repel away from each other and curve up and down to get further away from each other.
If one joule of work is done in moving one coulomb of charge between two points in an electrical field, what is the potential difference between the two points?
One volt.
What happens when a current flows through a wire?
A magnetic field is produced.
What does the direction depend on in a magnetic field around a wire?
The direction of the current flow.
When figuring out the movement of a negative charge in an electrical field what hand should be used and what stands for what?
The right hand. The index finger represents what direction the field lines are going in. The middle finger represents the direction of the negative charge current (the initial direction the negative charge is taking).The thumb represents the motion/ movement of the negative charge (Where the negatively charged particle is actually going to go).
When figuring out the movement of a positive charge in an electrical field what hand should be used and what stands for what?
The left hand. The index finger represents what direction the field lines are going in. The middle finger represents the direction of the positive charge current (the initial direction the positive charge is taking).The thumb represents the motion/ movement of the positive charge (Where the positively charged particle is actually going to go).
When figuring out the direction of charged particles in electrical fields what do the dots represent?
Field lines coming out of the page.
When figuring out the direction of charged particles in electrical fields what do the arrows/croses represent?
Field lines going into the page.
What do particle accelerators do?
A particle accelerator speeds up and increases the energy of a beam of particles by generating electrical fields that accelerate the particles and magnetic fields that steer/deflect the particles and forces them. This results in high energy collisions of charged particles to produce other particles.
What is the simplest type of particle accelerator and how does it work?
The simplest type of particle accelerator is a CRT ( the tube used in oscilloscopes and old TV’s). Electrons are negatively charged and are repelled from the negative electrode (the cathode) and attracted towards the positive one (the anode).
DON’T DESPERATELY NEED TO KNOW!!!!
What are the three types of particle accelerator?
Linear accelerators, Cyclotrons and Synhcrotrons.
What do all particle accelerators have?
A source of particles, beam pipes, accelerating structures, a system of magnets and a target
What are facts about linear accelerators?
- The largest linear accelerator is 3 km long and is located at Stanford university in California.
- In a linear accelerator, the electrons pass through a series of electrodes. These keep the electrons moving rather than having to use increasingly large voltages.
- To keep the electrons moving they must always be moving from a negative electrode to a positive one.
What are facts about the cyclotrons?
- A cyclotron uses ‘ D ‘ shaped electrodes to accelerate particles in a circular path.
- Were used in old TV’s
What are facts about synchrotrons?
- A synchrotron works on the same principle as a linear accelerator but is bent into a ring so the charged particles can be given more energy each time they go round.
- The Large Hadron Collider (LHC) is an example of a synchrotron particle accelrator.
- The LHC is the worlds largest particle accelerator at CERN, Switzerland. It is 27 km in length and cost £2.6 billion to build.
what is the potential difference between two points a measure of?
The work done in moving one coulomb of charge between two points.
what does a moving charge produce?
A magnetic field.
What is the charge of a proton?
1.6 x 10-19 C
What is the charge of an electron?
-1.6 x 10-19 C
Why are protons and the neutrons not fundamental particles?
They are composed of other particles/quarks, (fundamental particles are not). (they are composite
particles).
All baryons are hadrons, but not all hadrons are baryons why is this statement correct?
Baryons are (hadrons as they are) composed of (three) quarks. Mesons/some hadrons are made from a quark - anti-quark pair so are not baryons.
