Particle Physics Flashcards
Name the three things conserved in nuclear reactions.
Conservation of mass-energy
Conservation of momentum
Conservation of charge
Who first postulated the neutrino? Why?
Pauli. Momentum not conserved in beta decay. Neutrino had the missing momentum.
Who named the neutrino? What is the symbol for the neutrino?
Enrico Fermi. v.
What is the formula for the Cockcroft and Walton Experiment? What is the historical significance?
7Li3 + 1H1 –> 4He2 + 4He2 + Energy
First experimental verification of E=mc(2)
First transmutation of an atom using ARTIFICIALLY accelerated particles.
What is the formula for the first transmutation of an atom with NATURAL accelerated particles?
4He2 + 14N7 —> 17O8 + 1H1
What is an advantage of circular particle accelerators over linear particle accelerators?
Particles can achieve greater speeds/energies
They are more compact.
What is pair production? Why are photons always produced in pairs when annihilation occurs? What is pair annihilation?
Particle and its antiparticle created from a gamma ray.
conserve momentum
A particle and its antiparticle annihilate to form a pair of photons.
Why is the mass of 1H1 different from than the mass of the proton?
1H1 contains the mass of the electron.
A proton may be classed as a hadron explain why?
Experiences strong nuclear force
A proton may be classed as a baryon explain why?
baryons composed of three quarks
State the four fundamental forces of nature in order of increasing strength. Give each of their ranges in brackets beside them.
Gravity (Infinite), Weak Nuclear Force(short), Electromagnetic(Infinite), Strong Nuclear Force(short)
State the quark composition for a (a) proton (b) anti-neutron
u,u,d. anti-u, anti-d, anti-d
In a circular accelerator how are the particles (a) accelerated (b) kept in circular path. (c) detected.
Why is the tube evacuated?
Voltage (for straight accelerator) Magnetic Fields and electric fields (for circular); Magnetic Field; fluorescence when particles hit a zinc sulfide screen
So that particles don’t collide with gas particles.
Why are neutrinos hard to detect?
Very small mass and no charge
Name the two families of subatomic particles and distinguish between them.
Fermion-Half integer spin. Subject to exclusion principle
Boson-Whole integer spin. -not subject -transmit a force
Name the two families of fermion and distinguish between them.
Hadron-Made up of quarks. i.e. protons and neutrons
Lepton-Fundamental Particle. i.e. electrons, neutrinos
Name the two families of hadrons and distinguish between them.
Baryon-3 quarks. i.e. proton, neutrons
Meson-Quark-antiquark. i.e. pi 0
What is the main fundamental force experienced by neutrinos?
Weak Nuclear
Name one fundamental particle subject to the strong nuclear force.
Quark
Why must two positrons be accelerated to high speeds to collide?
To overcome forces of repulsion.
what is antimatter?
Matter that has the same mass as another particle but opposite charge.
What antimatter particle was discovered from cosmic rays in 1932? Give its symbol.
positron; e+
What happens when a particle meets it antiparticle?
Pair annihilation occurs followed by creation of two photons.
Construct all the possible quark combinations for the mesons.
Give a name and charge for each.
U + anti u = pi0 Charge: 0 Name: Pi-neutral
U + anti d = pi+ Charge: +1 Name: Pi-plus
d + anti u = pi- Charge: -1 Name: Pi-minus
d + anti d = pi0 Charge: 0 Name: Pi-neutral
