Zusammenfassung der Ressource
Particle Physics - A2 - OCR
- Hadrons
- Baryons
- Nucleons - protons and neutrons
- All baryons decay to protons
- Baryon number
- the number of baryons in a reaction never changes
- The proton and neutron each have a baryon number of 1
- Mesons
- They are unstabe
- Baryon number
- All mesons have a baryon number of 0 as they aren't baryons
- Pions and Kaons
- Pions are the lightest mesons
- There are 3 types with different charges - π0, π+, and π−
- Kaons are heavier and more unstable
- There are also 3 types with different charges - K+, K0, K−
- Hadrons are particles that are held together by strong nuclear force
- Letptons
- Leptons do not feel the strong nuclear force.
- There are 3 types of Lepton - electron, muon and tau which all have a leton number of 1
- the electron, muon and tau all have a charge of -1
- Neutrinos - these have almost zero mass and zero electric charge
- each types of lepton has a neutrino form as well, with a charge of 0
- they have the same lepton number as the non neutrino form though
- Anti particles
- Every particle has an anti particle, that will have opposite charge, but the same lepton or baryon number
- Mesons are their own antipartices
- Energy can be converted into matter as E=mc2
- However, when energy is converted into matter, you will produce equal
amounts of anti matter and matter
- Particle-Antiparticle Pair is produced from a single photon, if there is enough energy
- Pair Annihilation happens when a particle meets an antiparticle, all the mass is converted to energy
- For instance an electron and positron will combine to form a gamma ray
- Quarks
- Quarks are the fundamental particles, that make hadrons
- There are many types - up, down and strange (the ones to
know) and a few others called top,bottom and charm
- Baryons are made from 3 quarks
- Protons-uud
- Neutron-udd
- antiprotons and antineutrons are made up of the equivalent antiquarks
- Antiparticles are made up of antiquarks
- Note: antiquarks have the opposite
charge and baryon number!
- Quarks have charge and a baryon number -
strange also has a strangeness value of 1
- Charge:
Up=+2/3
Down=-1/3
Strange=-1/3
- Baryon Number:
all =+1/3
- Mesons are a quark and an antiquark
- Pions are made from up and down quarks
- Kaons have strangeness