Building a cold neutron beam; A pure dream becomes reality

Journal Article · Wed Jan 01 04:00:00 EST 1992 · Engineering, Cornell Quarterly; (United States)

OSTI ID:7234593

Clark, D D ^[1]

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1. Cornell Univ., Ithaca, NY (United States). Dept. of Nuclear Science and Engineering

How does a neutron interact with matter and what makes it a useful experimental probe Apart from very small or rare effects, neutrons interact only with nuclei and only via the nuclear force. A neutron does not ionize the atoms along its path, and it penetrates matter readily, keeping the same velocity until it interacts with a nucleus, where it is either deflected or absorbed. Quantum mechanics predicts probabilistically both the distance traveled before an interaction and whether deflection or absorption will occur. Both processes have important roles. This paper reports on neutrons which are leased in nuclear fission at energies in the millions of electron volts, and they lose energy by deflection, scattering in billiard-ball-like collisions with the nuclei of moderators such as hydrogen. When their kinetic energy is reduced to the same level as the thermal-motion energies of the moderator atoms, they are as likely to gain energy as lose it in any given collision. The distribution of their kinetic energies then reaches an equilibrium that is close to the Maxwellian energy distribution of the moderator atoms at the temperature of the medium, and they are called thermal neutrons.

• OSTI ID: 7234593
• Journal Information: Engineering, Cornell Quarterly; (United States), Journal Name: Engineering, Cornell Quarterly; (United States) Vol. 26:3; ISSN ECQUA; ISSN 0013-7871
• Country of Publication: United States
• Language: English

Related Subjects

663610* -- Neutron Physics-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARYONS
BEAMS
BOLTZMANN STATISTICS
COLD NEUTRONS
ELEMENTARY PARTICLES
ENERGY
ENERGY LOSSES
FERMIONS
FISSION
HADRONS
INTERACTIONS
KINETIC ENERGY
LOSSES
MATTER
MECHANICS
NEUTRON BEAMS
NEUTRONS
NUCLEAR FORCES
NUCLEAR REACTIONS
NUCLEI
NUCLEON BEAMS
NUCLEONS
PARTICLE BEAMS
QUANTUM MECHANICS
SCATTERING