Natural boron has a density of 0.128 x 1024 atoms/cm. its microscopic cross sections for neutron absorption and scattering are o-760 b and o,-4 b, respectively, both at thermal energy of 0.025 ev. calculate the macroscopic cross sections at 0.025 ev for absorption, scattering, and total interaction. (a) what fractional attenuation will a 0.025 ev neutron beam experience when traveling through 1 mm of boron? assuming the absorption cross section has "1/v" energy dependence (where v is the neutron speed), calculate the macroscopic cross sections of boron for neutrons at 0.0025 ev and 100 ev energies. what thickness of boron is required to absorb 50 per cent of a 100 ev neutron beam? (b) (c) (d)