Chapter 8-Particle Physics Flashcards
What is it called when the proton fragmented into a shower of particles rather than recoiling when colliding with a proton
Deep inelastic scattering
Protons contain not balls of positive charge but….
Localised charge centres
Electrons interact with charge centres via the
Electrostatic force (Coulomb's law/ inverse square law)
How many quarks in a proton
3
What are charge centres in a proton or neutron called
Quarks
What charge do up quarks have
+ 2/3 e
What charge do down quarks have
-1/3 e
What is e in charge terms
e= elementary charge
In order to break quarks apart what is needed
High energy bombarding electrons
A proton is made from which charge types
Up, up, down
Total charge = 1
A neutron is made from which quark types
Down, down, up
Total charge= 0
Neutron total charge
0
Proton total charge
+1
Quark and antiparticles have the exactly the same
Mass
Quarks and electrons, and antiparticles have different
Charges (opposite)
Antiparticle to an electron
Charge?
Positron
e+
Rest mass of both an electron and a positron
9.1x10^-31 kg
Einsteins theory of special relativity predicted that
The faster things go, the heavier they become
What does ‘u’ stand for (as a unit)
Unified atomic mass unit
What is one unified atomic mass unit equal to?
1/12 of the mass of a carbon-12 atom
1.66 x10^-27 kg
Using Einstein’s equation what is another unit for mass
MeV/c^2
Or
GeV/c^2
Particle production equation
Photon ➡️ electron + positron
Particle annihilation equation
Electron + positron ➡️ photon(s)
Pair production in a bubble chamber shows
Conservation of mass-energy
When pairs are created the charge is
Conserved
Zero before= e+ + e- = 0 after
Momentum is conserved and seen in pair forming from bunker chamber due to
Equal but opposite curvature of the two particles’ paths
What does a PET scan do
Detects activity of the brain and forms an image
From an annihilation often a pair of ____ are released
Gamma rays /detectable charged particles
How do PET scans work
- injected w radioactive element into brain
- v quick half life so decays quickly
- when decaying each oxygen-15 nucleus emits a positron that immediately annihilates with a local electron to form two gamma rays
- as positron and electron are stationary, the gamma rays move apart in opposite directions, to be detected by scintillator
- part of brain the come from deduced from difference in time they take to reach the scintillators
- computer produces resulting image
e value (number)
1.6 x10^-19 C
Electron and its antiparticle the positron are members of a group of fundament particles called
Leptons
Two other leptons w greater mass
Muons
Taus
Charge of leptons
e- /anti= e+
1 st generation lepton
Electron
2nd generation lepton
Muon
3rd generation lepton
Tau
First generation positive quark
Up quark
2nd generation positive quark
Charmed quark
3rd generation positive quark
Top quark
1st generation negative quark
Down quark
2nd generation negative quark
Strange quark
3rd generation negative quark
Bottom quark
Charge of positive quarks
+ 2/3 e
Charge of negative quarks
-1/3 e
Particles made from three quarks or three antiquarks are called
Baryons
What are the two types of hadrons called
Baryons
Mesons
Particles made from two quarks are called
Mesons
In a reaction the total number of baryons is
Conserved
Each quark has baryon number
+ 1/3
One baryon has baryon number
1
One antibaryon has baryon number
-1
Those with one strange quark in a meson are called
Kaons
Kaon symbol
K+
K-
In any particle interaction, the charge is
Always conserved
In any particle interaction the baryon number is
Conserved
In any particle interaction the lepton number is
Conserved
In any particle interaction the strangeness number is
Conserved
What do neutrinos or antineutrinos not carry
Charge
What thing, that we come into contact with daily, emits millions of neutrinos passing through our eyes every second
The sun
All leptons and neutrinos carry a lepton number of
+1
All antileptons and antineutrinos carry a lepton number of
-1
Strangeness is conserved in….
Nuclear reactions
Strange quarks have a strangeness number
+1
Anti strange quarks have strangeness number
-1
What is wave particle duality
The theory that waves behave like particles and waves
What are photons
They are photons of electromagnetic radiation
What is planks constant
6.63 x10^-34 Js
Equation proving waves with particle properties
E= hf
Equation proving particles with wave properties
p= h/ wavelength
What is the common factor between equations that proves wave particle duality
Planks constant
The key property proving light behaves like a wave
Diffraction
The result of wave superposition
