Basic concept and characteristics of beam quality indicator for continuum neutron spectra

Characteristics of a beam quality indicator (BQI), which has been recently developed to determine an effective energy of neutron beams with continuum spectra, are studied by means of a simplified calculation. The effective energy is defined with respect to a thickness ratio corresponding to the ratio of two energy dependent cross sections. The thickness ratio is defined such that the transmittance of Pb and Ti in the range less than 100 meV is the same. The Maxwell distribution is assumed in the calculations. Basic design parameters are given in the study.