1.1 This test method describes procedures for measuring reaction rates by the activation reaction ⁵⁴Fe(n,p)⁵⁴Mn.

1.2 This activation reaction is useful for measuring neutrons with energies above approximately 2.2 MeV and for irradiation times up to about 3 years (for longer irradiations, see Practice E 261).

1.3 With suitable techniques, fission-neutron fluence rates above 10⁸ cm²s¹ can be determined. However, in the presence of a high thermal-neutron fluence rate (for example, >2 10¹⁴ cm²s ¹) ⁵⁴Mn depletion should be investigated.

1.4 Detailed procedures describing the use of other fast-neutron detectors are referenced in Practice E 261.

This 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.