Fission. Neutrons are like neutral protons. Mass is 1% larger No coulomb force Neutron lifetime is long, but eventually decays to a proton. l = 624 s. Neutrons can interact directly with nuclei. Strong nuclear force Neutron capture reactions usually involve gamma ray emission. Neutrons.
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Neutrons are like neutral protons.
Mass is 1% larger
No coulomb force
Neutron lifetime is long, but eventually decays to a proton.
l= 624 s
Neutrons can interact directly with nuclei.
Strong nuclear force
Neutron capture reactions usually involve gamma ray emission.
Neutrons in nuclear reactions have distinct ranges of energy.
Slow or thermal neutrons with energies under 1 eV
Fast neutrons with energies from 100 keV to 10 MeV
Relativistic neutrons with energies over 1 GeV
What is the kinetic energy of a thermal neutron?
It must be about kT.
At 20 Â°C, kT = 1/40 eV
Better is (3/2)kT
3 degrees of freedom
K = 0.038 eV
Heavy nuclei have higher rest masses than two lighter nuclei.
U-235: -7.2 MeV/nucleon
Daughters: -8.5 MeV/nucleon
The binding energy difference is released when heavy nuclei split.
Requires quantum tunneling
Ejects excess neutrons
Fission is made more likely after neutron capture.
The energy released energy from uranium fission can heat water.
The heated water can drive a steam turbine and electric generator.
This is the basis for nuclear power plants.
World Nuclear Association
Nuclear fission of 235U produces multiple neutrons per reaction.
Neutron energy is important to reaction.
235U uses thermal neutrons
238U absorbs fast neutrons
Neutrons sustain the reaction.
Moderators slow down fast neutrons
Absorbers capture neutrons
Releases 208 MeV
Fission is exothermic.
Excess energy available in reaction
Uranium fission produces neutrons.
Needed for chain reaction
An uncontrolled chain reaction creates a nuclear explosion.