The Study On The Shielding Of The Device Of Detecting Contrabands By 14MeV Neutron Sources

In the several decades, various terrible affairs and drug traffic activities take place continuously because of the fluctuation of the world political structure. in order to stop the similar affairs, more countries pay attention to the detection of drugs and explosives. Especially after American 911 affairs,all countries government do more to value the safety, check of various dangerous goods and examination work.The techniques used to thoroughly inspect various size objects were either material non-specific, such as x-ray or manual. The latter, even when considered reliable, is highly labor intensive and can hardly be expanded to meet the challenge of abating the flow of drugs or intercepting the rarer events of explosives in containers or luggage. Hence, prompt gamma-rays induced by neutron analysis, which can be used to detect explosives rapidly, no-intrusively, automatically, play a very important role in detection.But it is important to ruduce the interference of theγ-rays from orther materials .Explosives, narcotics, and other contraband materials contain various chemical elements such as H, C, N, O, etc. in quantities and ratios that differentiate them from each other and from other innocuous substances. Neutrons andγ-rays have the ability to penetrate through various materials to large depths. They are able to interrogate, in a non-intrusive manner, volumes ranging from suitcases to Sea-Land containers. When neutrons make reaction with the elements of materials, the elements emit characteristicγ-rays which are the"fingerprints"of each isotope. We can determine if they are explosives according to their components and concentration from the data of analyzingγ-rays energy-spectrum.In fact, events of explosives in containers or luggage are rare,the result is easy to be interrupted byγ-rays released from other materials , it is very important for us to reduce the interruption from other materials.In this article, the shielding research of the fundamental device of detecting threats using 14MeV neutron is introduced to us. The experimental device is established and all vital parts are designed for better shielding and detection effects.Through experiments the shielding about the sample testing room and the detector are researched.At last when the Pb thickness is fixed on 8 cm and the detector is flat with its shielding device section.the result is approving. 400g contrabands simulants can be detected in this total experimental device.