Low-energy neutron scattering from heavy nuclei

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5503737

Horton, C A

Fast neutron inelastic scattering cross sections for the 44.9-keV level in [sup 238]U and the 49.4-keV level in [sup 232]Th, and the elastic scattering cross sections of [sup 209]Bi and [sup 232]Th have been measured using the neutron time-of-flight technique, at an incident neutron energy of 127 keV at six scattering angles from 45[degrees] to 122.5[degrees]. Neutrons were produced by the [sup 7]Li(p,n)[sup 7]Be reaction. A detector using two photomultiplier tubes in fast coincidence was built for these low-energy measurements. The detector efficiency was determined by comparison with that of a [sup 235]U fission chamber. Special attention was paid to determining the efficiency near the [sup 7]Li(p,n)[sup 7]Be reaction threshold. The spectrum unfolding included the removal of tails on the peaks which were assumed to be exponential functions. The inelastic peaks were stripped from the elastic peaks by using the shape of the bismuth elastic peak as a standard. Corrections for neutron attenuation were computed analytically. Corrections for multiple scattering were determined using a Monte Carlo method. Results were normalized to the [sup 238]U differential elastic scattering cross sections and angular distributions. The angular distributions and integrated cross sections are compared with the ENDF/B-VI evaluation cross sections and with results at similar energies from previous measurements. The use of iron neutron filters for measuring cross sections at low energies is also discussed.

• Research Organization: Massachusetts Univ., Lowell, MA (United States)
• OSTI ID: 5503737
• Country of Publication: United States
• Language: English

Related Subjects

663430* -- Nucleon-Induced Reactions & Scattering-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACTINIDE ISO
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALKALINE EARTH ISOTOPES
ALPHA DECAY RADIOISOTOPES
ANGULAR DISTRIBUTION
BARYONS
BERYLLIUM 7
BERYLLIUM ISOTOPES
BETA DECAY RADIOISOTOPES
BISMUTH 209
BISMUTH ISOTOPES
CALCULATION METHODS
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
DAYS LIVING RADIOISOTOPES
DISTRIBUTION
ELASTIC SCATTERING
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTARY PARTICLES
ENERGY RANGE
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FAST NEUTRONS
FERMIONS
HADRONS
HEAVY ION REACTIONS
HEAVY NUCLEI
INELASTIC SCATTERING
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
KEV RANGE
KEV RANGE 10-100
KEV RANGE 100-1000
LIGHT NUCLEI
LITHIUM 7 REACTIONS
MEASURING INSTRUMENTS
MINUTES LIVING RADIOISOTOPES
MONTE CARLO METHOD
MULTIPLE SCATTERING
NEUTRON DETECTORS
NEUTRONS
NUCLEAR REACTIONS
NUCLEI
NUCLEONS
ODD-EVEN NUCLEI
RADIATION DETECTORS
RADIOISOTOPES
SCATTERING
SPONTANEOUS FISSION RADIOISOTOPES
STABLE ISOTOPES
THORIUM 232
THORIUM ISOTOPES
TIME-OF-FLIGHT METHOD
URANIUM 235
URANIUM 238
URANIUM ISOTOPES
YEARS LIVING RADIOISOTOPES