PHYS 182 Lecture Notes - Lecture 13: Snolab, Hydrostatic Equilibrium, Chromosphere
PHYS182: Our Evolving Universe
2017-10-24 LEC 13
Standard model of particle physics
- Purple: particles that make up
most of the matter
- Green: things associated with
the electron
- Blue: particles that carry forces
- Recall: the sun emits energy due
to nuclear reactions, which
involve mainly the weak nuclear
force
3 forces of nature besides gravity
- Electromagnetic forces
- Strong Nuclear Force
- Weak Nuclear Force
Beta Decay
- Radium emits energy and releases a positron
- This process at the level of the fundamental constituency:
o The proton turns into a neutron and a neutrino or a muon is released
- This process is ultimately responsible for what happens in the sun
o Start with 4 hydrogen nuclei and end up with 1 He
- Start out with 4 protons Ă 2 of them turn into neutrons via Ăź-decay
- A further proton joins the deuterium and forms an unstable intermediate
o Two of these intermediates combine and eject 2 protons to create
helium
Fission vs. Fusion
- Fusion: Taking smaller elements and forming larger
elements
- Fission: Taking a large element and splitting it into smaller
elements
Structure of the Sun
- Outside Ă inside: Surface, Convection zone, Radiation
zone, the core
- The structure of matter at the surface is atomic, but at the
core the temperature is much higher, so instead of atomic matter, you have a plasma
o Since nuclei are free, they can hit each other and this is where nuclear reactions take
place
- Each second, 1011 kg of H is converted to He
- Gradually the composition of the sun is changing:
o The H fraction is decreasing and the He is increasing
o There is a second stage where He fuses, and it stops at the level of Carbon because at this
point it would cost energy to do fusion
o With larger nuclei you only gain energy by fission
PHYS 182
R. Branden-
berger
My Research
Chapter 1
Chapter 2
Chapter 3
Chapter 4:
Part A
Chapter 4:
Part B
Chapter 5
Chapter 6
Chapter 7
Beta Decay
112 / 136
PHYS 182
R. Branden-
berger
My Research
Chapter 1
Chapter 2
Chapter 3
Chapter 4:
Part A
Chapter 4:
Part B
Chapter 5
Chapter 6
Chapter 7
The Proton-Proton Fusion Chain
114 / 136
PHYS 182
R. Branden-
berger
My Research
Chapter 1
Chapter 2
Chapter 3
Chapter 4:
Part A
Chapter 4:
Part B
Chapter 5
Chapter 6
Chapter 7
Beta Decay
113 / 136
Document Summary
Purple: particles that make up most of the matter. Recall: the sun emits energy due to nuclear reactions, which involve mainly the weak nuclear force. Radium emits energy and releases a positron. This process at the level of the fundamental constituency: the proton turns into a neutron and a neutrino or a muon is released. This process is ultimately responsible for what happens in the sun: start with 4 hydrogen nuclei and end up with 1 he. Start out with 4 protons 2 of them turn into neutrons via -decay. A further proton joins the deuterium and forms an unstable intermediate: two of these intermediates combine and eject 2 protons to create helium. Fusion: taking smaller elements and forming larger elements. Fission: taking a large element and splitting it into smaller elements. Outside inside: surface, convection zone, radiation zone, the core. Each second, 1011 kg of h is converted to he.
