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| Science & Technology |
| Neutron Scatter Camera Detects Shielded Radiation To Find Smuggled Nuclear Material |
| 2007-11-26 |
| In an effort to find an answer to the problem of identifying smuggled special nuclear material (SNM), researchers at Sandia National Laboratories in California say a neutron scatter camera they are developing may be able to detect radiation from much greater distances and through more shielding than current detection instruments. The neutron scatter camera, says Sandia physicist Nick Mascarenhas, has the capability to count neutrons from a source of SNM and localize it â meaning it doesnât only indicate there is radiation present, but also where it is emanating from and, under some circumstances, how much. âThis instrument can pinpoint a hot spot in another room through walls, something not typically possible with gamma-ray detectors,â says Mascarenhas. âPerformance-wise, itâs beating the older technologies, but we want to continue to push the limits of sensitivity and detection distance.â Distance, says Mascarenhas, is a significant benchmark because it means the neutron scatter camera has the potential to detect through various types of shielding, a concern at any border crossing or point of entry. Results of neutron scatter camera testing have been encouraging. âItâs more penetrating and can detect unambiguously at a greater distance and through more shielding,â says Jim Lund, who manages the Rad/Nuc Detection Systems group at Sandia/California. [..] The neutron scatter camera consists of elements containing proton-rich liquid scintillators in two planes. As neutrons travel through the scintillator, they bounce off protons like billiard balls. This is where âscatterâ comes into play â with interactions in each plane of detector elements, the instrument can determine the direction of the radioactive source from which the neutron came. The neutron eventually flies off, but not before energizing the protons with which it has interacted. The proton will lose its energy in the scintillator. As that energy is lost, it is converted into light. Photomultiplier tubes coupled to the scintillator detect the light. Computers record data from the neutron scatter camera, and using kinematics, determine the energy of the incoming neutron and its direction. Pulse shape discrimination is employed to distinguish between neutrons and gamma rays. The biggest obstacle to the camera becoming widely adopted is the liquid scintillator, which is flammable, hazardous, and requires special handling. According to Mascarenhas, materials exist that could be used as a solid scintillator, but they need to be mass produced and made readily available in the U.S. for this purpose. Solid scintillator material, he says, is not in the scope of the current project but is a logical next step. |
| Posted by:3dc |
| #2 "liquid scintillator, which is flammable, hazardous, and requires special handling" The info is scant but I suspect that when the device is passed on to the engineers to build that they will find a way to address the "special handling" needs of the device if it is indeed useful. |
| Posted by: Throger Thains8048 2007-11-26 18:59 |
| #1 I'll see your unbathed, illiterate 14th century worshipping peasant and raise you the guys in the lunch room at Sandia Labs... |
| Posted by: M. Murcek 2007-11-26 18:54 |