Minimum detectable mass fraction of localised changes in biological matrices using neutrons in transmission

The value of the minimum detectable mass of an irregularity, which will change the neutron macroscopic cross section of a biological matrix by 1%, has been calculated by using neutron transmission technique. The biological matrices selected were ones in which neutron transmission provided better detection of elements than photon attenuation measurements. Best results were obtained, for the detection of bone marrow in bone (12.2 mg/g), Ca in bone (10 mg/g) and water in brain (6 mg/g). The minimum required number of neutrons and the exposure time required for the detection of irregularities in bone marrow have been calculated. (author)