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ABSTRACT:
Using a novel source and extraction geometry, Ka-Ngo Leung, Sami Hahto, and Taneli Kalvas of Lawrence Berkeley National Laboratory have devised a method for generating neutron pulses of 5 nanoseconds or less that can be used to detect explosives or fissile material in cargo containers.
The invention significantly improves upon existing short-duration neutron pulse sources that use a toroidal source and radial extraction. Rather than using multiple-slit extraction, which complicates alignment, the new method extracts and focuses the plasma, which is formed with an axial RF source, in a novel manner. The beam is accelerated through a three-stage acceleration column to a titanium target. The device can produce 5-nanosecond pulses.
In the new Berkeley Lab neutron generator, nuclear particles are generated only during the small time interval that the beam strikes the target. This greatly reduces the beam power delivered to the beam dump, requiring substantially less cooling and almost completely removing unwanted background particle generation. Similar spectrographic techniques can also be used for gamma ray detection, with the gamma ray sensor positioned at a greater distance from the material to be interrogated. |
