1. 7.3 The Structure of Matter

2. Rutherford Model 1911
Ernest Rutherford “atoms contain a very small heavy central positive nucleus,
with the e-
orbiting randomly
around.

4. Most a particles went straight through, but the ones that passed closest the Au nucleus were progressively more deflected.

5. Gold foil experiment :. atom is mostly empty space
Gold foil experiment : atom is mostly empty space with dense positively charged nucleus. Neg e- move in circular orbits about the +nucleus. e- attracted to nucleus by electrostatic F

6. He used the repulsion of the a particle & the angle of deflection.
An interesting discovery of Rutherford’s experiment was he estimated the diameter of the nucleus.
He used the repulsion of the a particle & the angle of deflection.
An a particle repelled straight back would stop for a moment. At that moment its KE = PE elc.

7. Bohr Model
Considers protons, neutrons, electrons as fundamental particles.

8. Standard Model
No longer considers protons, neutrons, fundamental particles.
Smaller subatomic particles
found – quarks & leptons are fundamental.
Forces are carried by particles too!
We will discuss gauge bosons
(force carriers later)

9. Antimatter particles
Same mass but opposite charge or other properties.
When a particle meets its antiparticle twin, they completely annihilate, destroy.

10. All matter classified Hadrons or Leptons Hadrons made from quarks.
p+ & no
Quark Confinement - Quarks can’t exist alone.

11. Protons, Neutrons: are baryons made of only up & down quarks.
1A. How many up & down quarks in a p+?
Charge = +1
Baryons have 3 quarks only.
2 up & 1 down.
u u d
+2/3 +2/3 – 1/3 = +1

12. 1b. A particle is composed of 1 anti-strange, & 1 down quark.
Write the symbols & charges for all the particles.
s d
+1/3 -1/3
What is its charge? 0.
What type of particle is it?
Meson.

13. Can the following rx happen? 226Ra + n 222 Rn + 1H.
Conservation Laws
Can the following rx happen?
226Ra + n Rn + 1H.
No.
Does not obey conservation of mass/charge.
Must also obey conservation of baryon and lepton number.

14. Data Booklet Quantum numbers: Charge# see table.
Baryon # – Baryons(1) Antibaryons(-1), Leptons(0) Quarks (1/3), Antiquarks (-1/3)
Lepton # – Leptons (+1), antileptons (-1)

15. 2. What is the baryon number of a proton an antiproton? a meson?
Proton = uud : +1/3 + +1/3 + +1/3 = +1.
Antiproton = uud : - 1/ / /3 = - 1.
A meson has the quark makeup (qq) so that it has a baryon number of +1/3 + -1/3 = 0.

16. 3. State whether the following reactions are possible.
Check B, L, q conservation
B 1 =
L 0 =
Q +1 =
B 1 =
L 0 =
Q 0 = 1 –
B ≠
L =
Q =
p n + e+ + n.
n p + e- + n.
n + p e+ + n.

17. 4. A negative pion p- is composed of an anti-up and a down quark
4. A negative pion p- is composed of an anti-up and a down quark. A proton collides with it a. State whether or not the products can be a neutron and an uncharged pion, po. Write the equation and use the conservation laws. b. Use the equation to deduce the quark composition of the uncharged pion.

18. Charge All stable particles must have whole number of elementary charge!
No stable particle can have + 1 1/3 charge but can have
+2, -1 etc.
Quarks cannot exist by themselves. (Quark confinement).

19. Quarks & Leptons 5:40 min. http://www.youtube.com/watch?v=aTFCKbZw8QY
Hamper pg 310 #
Quarks & Leptons 5:40 min.
Brian Cox Crash Course 13 min
Part 2

21. Forces & Force Exchange Particles 4 Fundamental Forces
The universe exists because the fundamental particles interact. These interactions include 4 attractive & repulsive forces, & decay. Force exchange particles are gauge bosons.
Strong Nuclear (Nuclear)
Electromagnetic
Weak (Nuclear)
Gravity

23. Matter emits and absorbs the force exchange particles in force interactions. Particles are called virtual because they’re so short lived – cannot be observed.

24. Why the repulsion?
How about attraction?

25. Feynman Diagrams
Represent nuclear reactions with the mediating force exchange particles. A graph. Antimatter st has arrow other way.
The conservation of charge, baryon, lepton, must be obeyed at the vertices. What goes in must come out.

26. 4. In positron decay, a proton becomes a neutron by emitting a positron and a neutrino. Write the decay equation. Sketch the Feynman diagram

27. 5. In beta decay, a neutron becomes a proton by emitting an electron and a neutrino. Write the decay equation. Sketch the Feynman diagram

28. 6. A proton in the nucleus can capture an e- from an inner orbit and combine with the e- to form a neutron. A neutrino is emitted in the process. Write the equation for the reactants and the products. Sketch the Feynman diagram.

29. Problem Set “Exchange Particles”.

30. Cern Standard Model http://www. youtube. com/watch
Cern Standard Model 5 minutes
Brian Cox “Crash Course in Particle Physics Part 1” 13 min
Brian Cox “Crash Course in Particle Physics Part 2” 27 min

31. Comprehensive Standard Model Summery (15 minutes) Cassiopeia

32. Quantum Song

34. What is Higgs Boson 3:30
What now for the Higgs 8:00 min w/ad.