FLUKA simulations and measurements for a dump for a 250 GeV/c hadron beam

FLUKA is a Monte Carlo code, transporting hadron and lepton cascades from several TeV down to a few keV (thermal energies for neutrons). The code is widely employed in various applications, such as particle detector design, shielding, radiation therapy, high energy physics experiments. The FLUKA results were compared with experimental data of dose equivalent and spectral fluence of neutrons produced by a 250 GeV/c proton/pion beam impinging on a beam dump installed in one of the secondary beam lines of the CERN super proton synchrotron (SPS). The dump is a shielding structure made of iron/concrete, designed to absorb completely the high-energy beam. The actual geometry of the clump was modeled in the simulations and the scoring of neutron track length was performed at various locations around it. Importance sampling and Russian Roulette mere used as variance reduction techniques. The simulations results were compared with experimental measurements performed with a Bonner sphere system for neutron spectrometry and various types of rem-counters, a tissue equivalent proportional counter (TEPC) and a set of bubble detectors. Some discrepancies found with the measured data can be explained by the presence of slits and openings between adjacent concrete blocks constituting the dump assembly. (20 refs)