Products of the Thermal-Neutroninduced Fission of U-235
Beta-delayed neutron emission
Allows Reactor
Control
Controlled Fission (Chain) Reaction
Reactors
Power reactors
Research Reactors
Converters
The Density of Nuclear Matter
The density is constant, and:
independent of A
~ everywhere inside a nucleus
Constant Density of Nuclear
Matter
Nucleons are closely packed in
an ~incompressible liquid-like
droplet
Binding
Why would protons and neutrons
stay
Fusion
Fusion
Nucleons like to
be together
Central
problem:
Fusion
How to provide Kinetic Energy to overcome the
Coulomb Barrier?
V ~ Z1Z2/(R1+R2)
Fusion
Central
problem:
Fusion
How to provide Kinetic Energy in order to
overcome the Coulomb Barrier?
V ~ Z
He-4 + He-4 Be-8 He-4 + He-4
He-4 + He-4 Be-8 He-4 + He-4 (~10-16 s)
If fast enough: Be-8 + He-4 C-12
(Q = 7.45 MeV)
Discovery of a needed Resonance:
(needed because without the C-12* resonance the
cross section for the reaction would be too small)
(C-12)
Relativistic Quantum Mechanics:
The Klein-Gordon Wave Equation
The Dirac Equation (for Fermions)
The concept of SPIN follows naturally
The Genealogy of Forces
Unified Theories
Physics & Cosmology
All Elementary Particles: either
Bosons or Fermions
Bosons
Products of Thermal-Neutroninduced Fission of U-235
Where Does the Energy Go?
Bulk: ~200 MeV
kinetic energy of the
fission fragments
Prompt Neutrons
Other
Only ~ 5 MeV !
Neutron-induced
Fission
Natural Uranium:
0.72% U-235
99.28% U-238
Controlled Fissi
The Exclusion Principle for
Fermions
1
1
Sz Sz
2
2
1
Sz
2
ATOMIC
PHYSICS
What maters
for Chemical
Properties is the
state of the most
loose electrons
The other, more
strongly bound
electrons are
merely passive
placeholders
ATOMIC
PHYSICS
Principal
quant
Fission Explosives
U-235 and Pu-239
Exponential increase in energy release of a
supercritical assembly
Without control Nuclear (atomic) Bomb
Neutron emission the Neutron Energies
Neutron-induced
Fission
Natural Uranium:
0.72% U-235
99.28% U-238
How to mak
Albert Einstein
1905
Nuclear Physics
The composition of
Nucleons
3 Quarks (u = up, d = down)
How the elementary particles interact
Exchange of mediators (bosons)
The forces
[MeV]
L
Bosons:
Fermions
[MeV]
L
The range of a force and the mass
of the mediat
Gun Design
Critical
assembly
(m~3-15 kg)
Normal Explosion
Fission Bombs
Gun-type Bomb
U-235
(very simple)
Implosion-type Bomb
Pu-239
(more complicated)
Why Pu only implosion-type?
Plutonium was first produced and isolated on
February 23, 1941 by Dr. Glenn
Building a nucleus:
Deuteron
Note: no
Coulomb
repulsion
Deuteron is barely bound!
Building a nucleus:
Dineutron?
NO
Coulomb
repulsion
Dineutron is NOT bound!
Building a nucleus:
Diproton?
STRONGC
oulomb
repulsion
Diproton is NOT bound!
Building a nucleus:
Controlled Fusion in Reactors
~14 MeV
Advantage:
Disadvantage:
Coulomb barrier for H-2
and H-3 the same as for
H-H
Most of energy carried by a
neutron, which is hard to
transform into useful forms
Controlled Fusion in Reactors
Controlled Fusion in Reactor
Building a nucleus: the Curve of Stability
N>Z
Away from the Curve of Stability (?)
Radioactivity
Alpha He nucleus
Beta - Electron
Gamma Photon
Fission breakup
into two nuclei
Evidence for the existence of Neutrinos
One more particle in a decay!
a Dec
Building a nucleus:
with Coulomb repulsion
Without Coulomb interaction
Building a nucleus: Shell Structure
Nucleons
are
Fermions !
Building a nucleus: Shell Structure
Nucleons
are
Fermions !
Building a nucleus: Large Nuclei
N>Z
Chicago, December 2, 1942
First sustained fission process in CP-1 (Chicago Pile)
Beta-delayed neutron emission
Allows Reactor
Control
Fusion the creation
of light elements
Fusion the creation
of light elements
Fusion
Fusion
Nucleons like to
be together
Fu
Diagnostic Nuclear Medicine
Gamma-ray Camera
Diagnostic Nuclear Medicine
PET Positron Emission Tomograph
CYCLOTRON
Building a nucleus: Binding Energy
Fission
Spontaneous Fission
Neutron-induced
Fission
Neutron-induced Fission Chain Reaction
Example: n + U
Applications: Nuclear Bombs and
Nuclear Power
Neutron emission
Statistical Evaporation Process
Neutron emission the Neutron Energies
Neutron-induced
Fission
Natural Uranium:
0.72% U-235
99.28% U-238
Products of the Thermal-Neutroninduced F
CREATION OF Plutonium Isotopes IN A REACTOR
U-239
Np-239
b
U-238
Pu-239
U-235
b
Spontaneous Fission
Z,N
Pu-240
n
Z,N
n
Pu-240
n
Pu-241
Pu-242
Grades
Pu-240 Content
Supergrade
Weapon grade
Fuel grade
Reactor grade
2-3 %
<7%
7-19 %
19 % or greater
Pu-238
Pu