Particle Physics Flashcards
How is Rutherford’s Scattering experiment conducted?
beam of alpha particles from a radioactive source were targeted towards a thin gold foil
Rutherford’s: Most alpha particles went straight through the gold foil, what does this show?
gold atoms were mostly emptty space
Rutherford’s: Some alpha particles were scattered at angles greater than 90 degrees, what does this show?
each gold atom has a positive nucleus with a radius less than about 10^-14m
Rutherford’s: What is the scattering of alpha due to?
electrostatic repulsion by the gold nucleus
What is the nucleus made up from?
neutrons and protons
What is a nucleon?
neutron or proton
What is the nucleus surrounded by?
cloud of electrons
What is equal in a neutral atom?
number of protons and electrons
How do you calculate the number of neutrons in an atom?
nucleon number - proton/atomic number
What is an isotope?
nuclei of the same element that have the same number of protons but different number of neutrons
What is the mass of a particle quoted in?
atomic mass units (u)
How much smaller is the volume of the nucleus than the volume of the atom?
10^15
Why is the mass of the atom approximately the same as the mass of the nucleus?
minuscule mass of electrons
What forces do protons within a nucleus experience?
large electrostatic repulsive forces
What force do all nucleons inside the nucleus experience?
strong nuclear force
When is nuclear force attractive?
up to 3fm
When is nuclear force repulsive?
below 0.5fm
What is the antiparticle of an electron?
positron
What is the antiparticle of a proton?
antiproton
What is the antiparticle of a neutron?
antineutron
What is the antiparticle of a neutrino?
antineutrino
What are fundamental particles?
no internal structure so cannot be divided into smaller particles
What are examples of fundamental particles?
electrons and quarks
What are protons and neutrons not fundamental particles?
made up of quarks
What are hadrons?
particles and antiparticles that are affected by strong nuclear force
How do hadrons decay?
weak nuclear force
What are the 4 hadrons?
protons, neutrons, baryons, mesons
What are leptons?
particles and antiparticles that are not affected by strong nuclear force
What are the 3 leptons?
electrons, neutrinos, muons
What force do both hadrons and leptons experience?
electromagnetic force
What are the 4 fundamental forces?
strong nuclear, electromagnetic, weak nuclear, gravitational
What is any particle made up of quarks called?
hadron
How many quarks does a standard particle of elementary charge require?
6
What are the 6 quarks?
up, down, strange, anti-up, anti-down, anti-strange
What is the quark make up of a proton?
U U D + e
What is the quark make up of a neutron?
U D D
Define radioactivity:
decay of an unstable nucleus
Which types of nuclei decay by emitting beta radiation?
beta plus and beta minus
What type of particles have negligible mass and no charge?
neutrinos
What is the make up of beta minus decay?
Neutron > proton + electron + electron antineutrino
What quark changes in beta minus decay?
down > up
What is the make up of beta plus decay?
proton > neutron + positron + electron neutrino
What quark changes in beta plus decay?
up > down
What is the nature of alpha?
helium nucleus
What is the nature of beta?
electron
What is the nature of gamma?
electromagnetic radiation (wave)
What is the range of alpha in air?
few cm
What is the range of beta in air?
about 1m
What is the range of gamma in air?
several km
What is the penetration ability of alpha?
0.2mm paper
What is the penetration ability of beta?
1-10 mm of aluminium
What is the penetration ability of gamma?
several m concrete
