  Neutron spectra in high-energy region between 1 and 100-MeV in the shield
configuration of the anti-proton target station and a 120-GeV proton beam at
Fermi National Accelerator Laboratory (Fermilab) were determined using the
reaction rate data obtained with the multi-foil activation method. Two kinds of
methods were employed for the determination of neutron spectra: one is the
fitting method which is newly developed in this work, another is the unfolding
method with SAND-II code. The calculations were performed using the PHITS. From
the comparison between the calculated and experimental neutron spectra, it
concluded that the PHITS can be used for shielding design of high-energy proton
accelerators.
