1.1 This test method covers procedures measuring reaction rates by the activation reaction ²⁷Al(n,α)²⁴Na.

1.2 This activation reaction is useful for measuring neutrons with energies above approximately 6.5 MeV and for irradiation times up to about 2 days (for longer irradiations, see Practice E261).

1.3 With suitable techniques, fission-neutron fluence rates above 10⁶ cm⁻²·s⁻¹ can be determined.

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

1.5 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.