The Low Energy Neutron Source (LENS) is an accelerator-based pulsed cold neutron facility under construction at the Indiana University Cyclotron Facility (IUCF). The idea behind LENS is to produce pulsed cold neutron beams starting with ∼MeV neutrons from (p,n) reactions in Be which are moderated to meV energies and extracted from a small solid angle for use in neutron instruments which can ope...

A bulk shielding experiment was performed at the D-T neutron source FNS, using the assembly simulating shield blanket, vacuum vessel and toroidal field coil (superconducting magnet) of ITER. The objective was to investigate the influence on nuclear parameters due to the nuclei involved in the toroidal field coil and the effect of B4C/Pb. The analysis was performed by MCNP4-A and the DOT3.5 (P5S...

We describe the use of the MCNP-PoliMi code to simulate, on an event-by-event basis, the detection of neutrons by organic scintillators. This code keeps track of single neutron interactions, including the collision nucleus, the energy deposited, and the time distribution of collision events. We show that the total pulse-height response is given by the sum of many possible neutron histories, eac...

The axial distribution of energy deposited in bremsstrahlung conversion targets is modelled using the Monte Carlo N -Particle (MCNP) code. Systems comprising a disc-shaped target, segmented axially, and a point source of paraxial, monoenergetic electrons (2, 7, 10, or 14 MeV) are considered. Thick tantalum and aluminium targets and also tantalum targets of optimum thickness are modelled. Energy...

In this work we present a predictive analytical model that encompasses the performance and scaling characteristics of a non-deterministic particle transport application, MCNP. Previous studies on the scalability of parallel Monte Carlo eigenvalue calculations have been rather general in nature [1]. It can be used for the simulation of neutron, photon, electron, or coupled transport, and has fou...

We present new results on neutron and gamma-ray pulse-height distributions (PHDs) measured with liquid scintillators from five plutonium-oxide samples of varying mass and burnup and a Cf isotopic source. We show that the analysis of the pulse-height distributions can be used to easily distinguish the fissile material (plutonium oxide) from the Cf source. Moreover, the slope of the measured puls...

The modelling with the Geant4 toolkit of moderated 3He-filled proportional neutron counters is studied. The energy deposition spectra by the neutron capture products in the gas counter is compared with experimental results. On the other hand, efficiency calculation for polyethylene moderated proportional counters are compared with experimental and MCNPX results.Finally, the application of the G...

Neutron detection time distribution is an important factor for the dead-time correction for moderator type neutron detectors used in pulsed radiation fields. Measurements of the neutron detection time distributions of multisphere LiI detectors (2Ó, 3Ó, 5Ó, 8Ó, 10Ó and 12Ó in diameter) and AB remmeter were made inside a ANL 20-MeV electron Linac room. Calculations of the neutron detection time d...