Download Nuclear Physics

Nuclear Physics
Historical background
Plum Pudding model (Electrons) JJ Thomson
1890s
Nuclear Model (positive nucleus) Rutherford + G&M
1911
Proton
Rutherford
1919
Neutron
Chadwick
1932
Thomson and Rutherford
Investigating atomic structure
• X-Ray diffraction
• Electron Diffraction
• Neutron Diffraction
• High Energy Electron Scattering
Stanford Linear Accelerator
The Stanford Linear Accelerator
in California.
Electrons are accelerated to
speeds close to the speed of light
as they travel down the long,
straight track; they are then
directed at a variety of targets in
the laboratories at the end.
Atomic Structure: Summary
 The a-particle scattering experiment provides evidence for the
existence of a small charged nucleus at the centre of the atom.
 Most of the mass of an atom is concentrated in its nucleus.
 The nucleus consists of protons and neutrons, and is
surrounded by a cloud of orbiting electrons.
 The number of protons and neutrons in the nucleus of an atom
is called its nucleon number (A)
 The number of protons in the nucleus of an atom is called its
proton number (Z).
Atomic Structure: Summary
 Isotopes are atoms of the same element (with the same proton
number) but with different neutron numbers.
 Different isotopes (or nuclide, if referring to the nucleus only)
can be represented by: the notation:
A
zX
 Diffraction and scattering techniques, using beams of X-rays,
electrons and neutrons, provide information about the
arrangement and separations of atoms in crystalline materials.
 High-energy electron scattering experiments can give evidence
of the dimensions of the nucleus.
Nuclear Physics: Summary
 Nuclear reactions can be represented by balanced
nuclear equations. ln any such reaction, the following
quantities are conserved: proton number Z, nucleon
number A, and ‘mass + energy’.
 ln nuclear fission, a heavy nucleus splits into lighter
fragments. In nuclear fusion nuclei join to form a more
massive one.
 In order to relate mass changes to energy changes,
we use Einstein's equation:
DE = Dmc2.
Nuclear Physics: Summary
 The binding energy of a nucleus tells us the energy required to
break up the nucleus into separate nucleons.
 The binding energy per nucleon gives us an indication of the
relative stability of the different nuclides.
 The variation of binding energy per nucleon shows that energy
is released when light nuclei undergo fusion and when heavier
nuclei undergo fission, because these processes increase the
binding energy per nucleon and hence result in more stable
nuclides.
Discovery of the proton
Discovery of the neutron
Questions:
1. In a nuclear reactor, a nucleus of uranium 238 may capture a
neutron and become a nucleus of plutonium 94. Electrons are
released. Write a balanced equation for this reaction, and
deduce how many electrons are released.
2. The Sun releases vast amounts of energy. Its power output is
4 x 1026 W. By how much does its mass decrease each
second as a result of this energy loss?
Binding energy per nucleon
Nuclear fission
Nuclear chain reaction
Nuclear Fusion
Nuclear fission
Albert Einstein
The first nuclear reactor
Control rods
Liquid drop model
Fusion reactor
Binding energy
Nuclear fission
Question
Question
Question
Question
Nuclear forces