Classification of low-energy neutron spectra behind the IHEP accelerator shield

Results of analyzing spectra behind the IHEP accelerator biological shield are presented. Spectrum classification enabling to refer them to three typical groups depending on the average energy of epicadmium spectrum part is suggested. Effects of shield thickness and composition as well as the accelerator operation modes on neutron spectrum dostortion has been analyzed. The example of applying suggested classification for interpreting indications of radiative neutron monitor is presented. It is concluded that the average energy of epicadmium neutrons is the suitable value, characterizing the real situation behind the accelerator shield. It consideres all the factors, including the location of work places with respect to radiation source and accelerator operation mode