Characteristics of the neutron field in the KEK counter hall

We have measured the neutron leakage spectra outside the shielding in the KEK counter hall using a multisphere technique supplemented by the 12C(n, 2n)11C reaction in a carbon activation detector. The neutron spectra were derived from the measurements using the LOUHI78 unfolding code. The shape of these unfolded neutron spectra matched very closely that of spectra calculated by O'Brien and McLaughlin. A comparison of the dose equivalent as derived from the spectra with that measured by a neutron dose equivalent meter confirmed that the dose equivalent meter measurements usually underestimate the dose equivalent by at least 30%.