The Simulation Of Neutron Radiography By Monte Carlo Method

As a non-destructive testing technique, fast neutron radiography has many unique advantages comparing with the others. Specially when can penetrate many metals, the heavy metal to examine the internal organic matter condition. The neutron radiography is based on the beam penetration object when will have the weaken basic principle. after the neutron incidence to the treats sample, because the neutron and the sample's atomic nucleus has the interaction the transmission neutron's intensity and the spatial distribution will change, the thermal neutron radiography resolution are high, at present will apply universally in the neutron radiography, the technology will be quite also mature. But the thermal neutron can only penetrate the thin sample, regarding shell such object, with difficulty obtains the sharp image likely. The fast neutron may penetrate the thick layer of the metal, therefore the fast neutron radiography may more make up the thermal neutron insufficiency in the aspect, but the fast neutron radiography's resolution compares the thermal neutron to want bad somewhat, because the fast neutron radiography its unique merit and the actual need have made in recent years also the very big progress and the widespread application, becomes the neutron radiography a hot spot. Monte Carlo Method can realistically describe the random events and simulate the experiment courses. It is very suitable for the calculation of particle transport problem which has the randomicity. The method has been widely used in the simulation of nuclear experiments include neutron detection. MCNP is a general program to simulate nuclear experiments, which is made by Los Alamos Station Lab in America based the Monte Carlo thoughts.The paper based on the neutron radiography's principle, uses the MCNP4C procedure, First simulates the fast, thermal neutron illumination copper and the polyethylene, draws their flux along with to illuminate the projectile thickness change the rule, simulates quick, the thermal neutron flight direction with to illuminate again in the working model vacuum eyelet parallel and the vertical time situation, this tallies with time the true photography situation, is advantageous in the examination through this method simulation neutron photography reliability, transforms using mathematic the analogue result data as the image, compared with quick, thermal neutron photography difference, and further changes the simulation structure the parameter, discusses this analogy procedure to experiment's instruction.