ASTM E 264 : 2008 : R2013

1.1This test method covers procedures for measuring reaction rates by the activation reaction ⁵⁸Ni(n,p)⁵⁸Co.

Note 1—The burnup corrections were computed using effective burn-up cross sections of 1650 b for  ⁵⁸Co(n,γ) and 1.4E5 b for  ^58mCo(n,γ).

FIG. 1 R Correction Values as a Function of Irradiation Time and Neutron Flux

1.2This activation reaction is useful for measuring neutrons with energies above approximately 2.1 MeV and for irradiation times up to about 200 days in the absence of high thermal neutron fluence rates (for longer irradiations, see Practice E261).

1.3With suitable techniques fission-neutron fluence rates densities above 10⁷ cm⁻²·s ⁻¹ can be determined.

1.4Detailed procedures for other fast-neutron detectors are referenced in Practice E261.

1.5The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.