Lithium Loaded Glass Fiber Neutron Detector Tests

اختصاصی از فی موو Lithium Loaded Glass Fiber Neutron Detector Tests دانلود با لینک مستقیم و پر سرعت .

Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive
neutron detection systems. The main reason for having neutron detection capability is to detect fission
neutrons from plutonium. The currently deployed radiation portal monitors (RPMs) from Ludlum and
Science Applications International Corporation (SAIC) use neutron detectors based upon 3 He-filled gas
proportional counters, which are the most common large neutron detector. There is a declining supply of 3 He in the world and, thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated.

Simulation of polyethylene-moderated plutonium neutron multiplicity measurements

اختصاصی از فی موو Simulation of polyethylene-moderated plutonium neutron multiplicity measurements دانلود با لینک مستقیم و پر سرعت .

Neutron multiplicity measurements are a useful technique for the characterization of special nuclear
material. This technique relies on the detection of correlated neutrons from fission events. As correlated
events are detected it is possible to determine the neutron multiplicity distribution for the sample. This
distribution is useful for identifying the material and estimating the mass. This work focuses on the
ability of the Monte Carlo code MCNP-PoliMi to simulate measured distributions. The experiment used
as the basis of comparison consisted of a 4.5 kg plutonium metal sphere surrounded by up to 6 in. of
polyethylene. A bank of 15 (3 He) detectors was used to detect the correlated neutron events. MCNP-
PoliMi was used to simulate the particle transport and a post-processing algorithm was developed to
apply detector deadtime effects and to determine the neutron multiplicity distributions. These
simulated distributions were then compared to the measured results. The simulation provided an
adequate estimation of the measured data. However, we observed a systematic over-prediction in both
the mean and the variance of the measured distribution.