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Flashcards in Particle Physics Deck (21):

What are particles?

Particle Physicists believe that everything is made out of combinations of particles.


What is The Standard Model?

The Standard Model in particle physics is a theory concerning the electromagnetic, weak, and strong nuclear interactions, which mediate the dynamics of the known subatomic particles.


What is Alpha radiation?

Alpha particles are emitted by:
- high mass
- proton rich unstable nuclei.

The Alpha particle is a helium nucleus; it consists of two protons and two neutrons.

It contains no electrons to balance the two positively charged protons.

Alpha particles are therefore positively charged particles moving at high speeds.


What is Beta radiation?

Beta particles are emitted by:
- neutron rich unstable nuclei.

The Beta particles are high energy electrons.

These electrons are not electrons from the electron shells around the nucleus, but are generated when a neutron in the nucleus splits to form a proton and an accompanying electron.

Beta particles are negatively charged.


What are Gamma Rays (radiation)?

Gamma rays are emitted by:
- most radioactive sources along with alpha or beta particles.

Gamma rays are electromagnetic waves of very short wavelength and high frequency.

After alpha or beta emission the remaining nucleus may still be in an excited energy state. By releasing a gamma photon it reduces to a lower energy state.

Gamma rays have no electrical charge associated with them.


What are the 4 fundamental forces of nature?

1. Strong interaction
2. Electromagnetic force
3. Weak force
4. Gravitational force


What is strong interaction?

The strong interaction is very strong, but very short-ranged.

It acts only over ranges of order 10-13 centimeters and is responsible for holding the nuclei of atoms together.

It is basically attractive, but can be effectively repulsive in some circumstances.


What is electromagnetic force?

The electromagnetic force causes electric and magnetic effects such as the repulsion between like electrical charges or the interaction of bar magnets.

It is long-ranged, but much weaker than the strong force.

It can be attractive or repulsive, and acts only between pieces of matter carrying electrical charge.


What is weak force?

The weak force is responsible for radioactive decay and neutrino interactions.

It has a very short range and, as its name indicates, it is very weak.


What is gravitational force?

The gravitational force is weak, but very long ranged.

Furthermore, it is always attractive, and acts between any two pieces of matter in the Universe since mass is its source.


What types of particles are there?

1. Fermions
2. Hadrons
3. Boson


What are Fermions?

Obey Pauli-Exlusion Principle

Two familes 1) Lepton and 2) Quarks

Leptons are not effected by the strong interaction, but Quarks are.

Fermions can have different quantum states (different energies)


What are Hadrons?

Quarks pairs/triplets held together by strong interaction

Baryons = made of 3 quarks

Mesons = made of quark-antiquark pair


What is a Boson?

A force/interaction carrier


What is the Pauli Exclusion Principle?

No two particles within an atom can share the same state.


What is the Higgs Boson?

Consider it as an anchor to particles - the more mass a particle has, the more Higgs boson ('anchors') it interacts with.

Mass is a measure of object's resistance to acceleration.

Is there more than one type of Higgs Boson? Paper soon to be published theorising that there is!

Discovered in the Large Hadron Collider at CERN on 4th July 2012. Needs 170 computing facilities in 35 countries as it produces 25 petabytes (1000 TB in 1 Petabyte).

It's discovery proved The Standard Model.


What are the 4 quantum numbers of electrons?

Electrons have 4 "quantum numbers" that describe their state:
1. shell number (principle)
2. sub-shell number (asimuthal)
3. orbital angular momentum in that sub shell (magnetic)
4. intrinsic angular momentm (spin)


What are the rules for particle combinations?

The charges of individual quarks must add up to make a whole number.


What are cosmic rays (radiation)?

Cosmic rays are emitted by:
- the supernovae of massive stars and active galactic nuclei.

Cosmic rays are immensely high-energy radiation, mainly originating outside the Solar System.

90% are protons. When they hit the upper atmosphere they get destroyed and creates neutronios, electrons, gammas, muons. They create so much energy.


What are neutrinos?

A neutral subatomic particle with a mass close to zero and half-integral spin, rarely reacting with normal matter.

Three kinds of neutrinos are known, associated with the electron, muon, and tau particle.

We don't see them directly but we see the flashes cause when they hit the fluid.


What is SNO+?

SNO+ - based in a disused mine in Canada. It's the Sudbury Neutrino Observatory.