The ionization method of measuring neutron energy

The absolute measurement of neutron flux density by ionization methods is discussed. The relation E υ = J υ W ρ between the energy E υ absorbed per unit volume of a solid medium and the ionization J υ produced in a gas-filled cavity in the medium, the average energy W expended by the ionizing particles in producing a pair of ions in the gas, and ρ the stopping power of the solid relative to the gas for these particles, is critically examined from the point of view of the measurement of the rate of absorption of neutron energy at any point in a hydrogenous medium. The accuracy attainable is assessed, in so far as it depends on our knowledge of the quantities ρ and W .