Deterioration of performance of neutron moderators under intense irradiation
In pulsed neutron sources, fixed moderators such as polyethylene and solid methane slow down fast (MeV) neutrons from the primary source to energies of use for spectroscopy (less than or equal to10 eV). Radiation-induced changes in their composition alter their spectral and pulse characteristics. We report the results of fitting time-average spectra from polyethylene and solid methane moderators in Argonne's Intense Pulsed Neutron Source as a function of total fast-neutron radiation dose. The thermal-to-epithermal flux ratio varies most significantly, while the Maxwellian energy and the parameters describing the epithermal component change only slightly. We have used modified forms of Westcott's joining function for this purpose. We provide an integral of the spectrum that is useful for determining the delayed neutron background.
- Research Organization:
- Argonne National Lab., IL (USA)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 6331692
- Report Number(s):
- CONF-8609234-9; ON: DE87011350; TRN: 87-030485
- Resource Relation:
- Conference: International collaboration on advanced neutron sources, Villigen, Switzerland, 22 Sep 1986; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
MODERATORS
PHYSICAL RADIATION EFFECTS
BOLTZMANN STATISTICS
EXPERIMENTAL DATA
IPNS-I SYNCHROTRON
MATHEMATICAL MODELS
METHANE
NEUTRON SLOWING-DOWN THEORY
NEUTRON SPECTRA
NEUTRON SPECTROSCOPY
PERFORMANCE
POLYETHYLENES
PULSED IRRADIATION
ACCELERATORS
ALKANES
CYCLIC ACCELERATORS
DATA
HYDROCARBONS
INFORMATION
IRRADIATION
NEUTRON SOURCE FACILITIES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC POLYMERS
POLYMERS
POLYOLEFINS
RADIATION EFFECTS
SPECTRA
SPECTROSCOPY
SYNCHROTRONS
430303* - Particle Accelerators- Experimental Facilities & Equipment
360605 - Materials- Radiation Effects