Reliability and bounds of unfolded spectral parameters. [Integrals]

Conference · Thu Jan 01 04:00:00 EST 1976

OSTI ID:7350422

Stallmann, F W; Kam, F B.K.

Presently available methods for unfolding the differential neutron spectrum from activation measurements do not provide any bounds on the accuracy of the results. Some indications for the reliability of the unfolded spectrum can be obtained from sensitivity studies, but these too cannot be converted into hard percentage figures. This is not due to some deficiency of the computing technique but results from the fact that the small number of activation data cannot provide enough information to sufficiently describe the differential spectrum phi(E) at a large number of energies E. More reliable data can be obtained for certain spectral parameters which result from integrating the neutron flux phi(E) multiplied with a given response function R(E) I/sub R/ = ..integral../sup 0//sup infinity//sub o/ R(E) phi (E)dE. Typical integral responses I/sub R/ are integral spectra, group fluxes, and damage integrals. Bounds for such integral responses can be computed with linear programming techniques. These bounds do not depend on a trial spectrum and can incorporate known bounds for the cross section and activity measurements. Numerical experiments with different response functions and different foil sets indicate which spectral parameters can be reliably computed from a given foil set and which foil set is best suited for the measurement of a given spectral parameter. Bounds are generally poor if a large part of both phi(E) and R(E) is below 1 MeV. Bounds which are within 20 to 50 percent of the true value of I/sub R/ can be obtained for higher energies in selected cases. Substantial improvements are possible if crude bounds are known for certain group fluxes obtained for instance from transport calculations.

• Research Organization: Tennessee Univ., Knoxville (USA); Oak Ridge National Lab., Tenn. (USA)
• OSTI ID: 7350422
• Report Number(s): CONF-760437-1
• Country of Publication: United States
• Language: English

Related Subjects

654003* -- Radiation & Shielding Physics-- Neutron Interactions with Matter
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARYONS
BOUNDARY CONDITIONS
CROSS SECTIONS
ELEMENTARY PARTICLES
ENERGY SPECTRA
FERMIONS
HADRONS
INTEGRALS
NEUTRON FLUX
NEUTRONS
NUCLEONS
RADIATION EFFECTS
RADIATION FLUX
RADIOACTIVITY
RELIABILITY
SPECTRA