Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
  • G01T3/00—Measuring neutron radiation

Definitions

• the present disclosure is generally related to reliable and inexpensive neutron detection and, in particular, to a high resistivity charge-coupled device (CCD) employing a plasma effect for energy measurement and particle identification for high-precision neutron imaging.
• CCD charge-coupled device
• a device in a particular embodiment, includes means for providing a reliable and inexpensive neutron detector comprising a charge-coupled device employing a plasma effect for energy measurement and particle identification giving reconstructed charge clusters for alpha particles that are easily distinguishable from photons, electrons, and muons.
• the device also includes means for operating the reliable and inexpensive neutron detector comprising the charge-coupled device for high- precision neutron imaging.
• the method also includes steps for operating the reliable and inexpensive neutron detector comprising the charge-coupled device for high-precision neutron imaging.
• Figure 1 is a diagram illustrating an embodiment of an apparatus including means for providing a reliable and inexpensive neutron detector comprising a charge-coupled device employing a plasma effect for energy measurement and particle identification giving reconstructed charge clusters for alpha particles that are easily distinguishable from photons, electrons, and muons and means for operating the reliable and inexpensive neutron detector comprising the charge-coupled device for high-precision neutron imaging; and
• Figure 2 is a flow diagram of an illustrative embodiment of a method including steps for providing a reliable and inexpensive neutron detector comprising a charge-coupled device employing a plasma effect for energy measurement and particle identification giving reconstructed charge clusters for alpha particles that are easily distinguishable from photons, electrons, and muons and steps for operating the reliable and inexpensive neutron detector comprising the charge-coupled device for high-precision neutron imaging.
• FIG. 1 a diagram illustrating an embodiment of an apparatus is depicted and indicated generally, for example, at 100.
• the apparatus 100 includes means for providing a reliable and inexpensive neutron detector comprising a charge-coupled device employing a plasma effect for energy measurement and particle identification giving reconstructed charge clusters for alpha particles that are easily distinguishable from photons, electrons, and muons 110 and means for operating the reliable and inexpensive neutron detector comprising the charge-coupled device for high-precision neutron imaging 120.
• the method 200 includes steps for providing a reliable and inexpensive neutron detector comprising a charge-coupled device employing a plasma effect for energy measurement and particle identification giving reconstructed charge clusters for alpha particles that are easily distinguishable from photons, electrons, and muons 210 and steps for operating the reliable and inexpensive neutron detector comprising the charge-coupled device for high-precision neutron imaging 220.
• the present invention is capable of considerable modification, alteration, and equivalency in form and function as will occur to those of ordinary skill in the pertinent arts having the benefit of this disclosure.
• the depicted and described embodiments of the present invention are exemplary only and are not exhaustive of the scope of the present invention.
• PROJECT TITLE Adaptation of CCDs for Neutron Detection and Imaging
• neutron detection is growing with the increasing demand for safer, environmentally sound nuclear energy, control of nuclear fuel, proliferation issues and quality control on hydrogen fuel cell development.
• Neutron imaging can complement the array of active interrogation techniques, and for particular materials assessment, micron-level resolutions may be desirable.
• the CCDs deployed for dark energy searches have been designed to measure a broad range of photon spectra.
• These high resistivity CCDs employ plasma effect for energy measurement and particle ID.
• the reconstructed charge clusters for alpha particles are easily distinguishable from photons, electrons and muons. It has been suggested that with proper conversion coatings and innovative reconfiguration, these CCDs, can be readily adapted to neutron detection, particularly for high-precision neutron imaging.
• KEY WORDS neutron detection, neutron imaging, materials control, fuel cycles.
• Cutting edge technology from cosmology can be applied to materials testing and control for nuclear power and proliferation issues, and other industrial applications. od and Apparatus for Adaptation of CCDs for Neutron Detection and Imaging
• ADS accelerator driven subcritical
• Active interrogation a measurement technique which uses a radiation source to probe materials and generate unique signatures useful for characterizing those materials, is a powerful tool for assaying special nuclear material.
• the most commonly used technique for performing active interrogation is to use an electronic neutron generator as the probe radiation source.
• Some examples include measuring the plutonium content of spent fuel, assaying plutonium residue in spent fuel hull claddings, assaying plutonium in aqueous fuel reprocessing process streams, and assaying nuclear fuel reprocessing facility waste streams to detect and quantify fissile material.
• Advanced fuels to be used in these initiatives will be hybridized mixtures of not only uranium and plutonium but also other transuranic elements including americium, neptunium, and curium.
• the presence of these extra materials adds complexity to the safeguards problem, which means more and advanced and complementary methods of interrogation need to be employed.
• neutron imaging has been identified as having an important role in materials assessment[3]. _
• Neutron imaging has wide industrial and scientific significance and can provide detailed information concerning the inner structure and composition of objects.
• the principle of neutron imaging is based on the attenuation, through both scattering and absorption, of a directional neutron beam by the matter through which it passes. Since different materials vary in their ability to attenuate neutrons, both composition and structure can be probed.
• the neutron imaging technique rather than being in competition with X-ray imaging, is entirely and ideally complimentary to it. Whereas X-rays are scattered and absorbed by the electrons, and as such atoms with greater electron shells interact more strongly, neutrons on the other hand interact with the atomic nuclei.
• Strong neutron sources like research reactors and accelerator-based spallation neutron sources can provide intense neutron beams, required for efficient and practical neutron imaging. Such beams have been successfully used for neutron radiography during the last two decades and neutron radiography has found its greatest applications in the examination of nuclear fuels, explosives, electronic components and engine turbines blades.
• Another example of a beam of collimated low energy (thermal) neutrons is the NIST Center of Neutron Research (CNR) facility.
• CNR NIST Center of Neutron Research
• Progress in furthering applications has led to the development of three-dimensional imaging methods (tomography), the exploitation of different neutron energies in the impinging beam to gain additional information and the real-time analysis of systems.
• the outcome from the application of the neutron imaging depends strongly on the neutron source properties and the detection system used. This has, in turn, generated much demand for research and development in these areas. _
• Detection systems have taken a big jump from conventional photographic film to digital realtime imaging.
• Thin-film-coated semiconductor devices have been investigated for thermal neutron detection, all of which have generally used 10 B, 6 Li, 6 LiF, and Gd coatings as the neutron reactive layer.
• Each has advantages and disadvantages regarding neutron detection efficiency and background gamma ray discrimination.
• Figure 2 illustrates the scheme: neutrons absorbed in the neutron-reactive film release charged particle reaction products in opposite directions. Only one reaction product may enter the semiconductor detector. Charged particles entering the detector lose their energy through Coulombic scattering, thereby creating a high-density plasma cloud of columnar ionization in the form of electron-hole pairs.
• the semiconductor diode detector is voltage biased to sep tive contacts.
• the DECam CCDs are 250 mm thick, fully depleted, back-illuminated devices fabricated on high-resistivity silicon.
• the CCDs considered for this proposal have 8 million 15 ⁇ X 15 ⁇ pixels.
• Figure 3(a) shows the 3-phase, p-channel CCD design.
• FIG. 3 (a) Cross-section of the LBNL fully depleted CCD.
• a conventional buried channel CCD is fabricated on a high-resistivity silicon substrate.
• a bias voltage applied to the backside electrode results in full depletion
• the DECam CCDs were tested for alpha particle detection in two energy regimes: a few MeV from an 241 Am source and a lower energy regime. For the latter, a 5 mm thick 10 B layer was
• the reconstructed charge clusters for cc-particles are easily distinguishable from photons, ⁇ -particles and muons.
• the reconstructed tracks produce large circular hits, with a second order moment of _2 pixels for energies of 4 MeV. Given the small pixels of the CCDs (15 ⁇ x 15 ⁇ ) the centroid of each of these cc-particle tracks can be measured with a precision of a few micrometers.
• Figure 4 shows the difference among the limited diffusion hits (point like events), tracks due to muons, and circles generated by cc-particles. Photons with energies below ⁇ 100 keV interact with the silicon mostly through photo electric effect, producing a localized charge deposit. At energies ⁇ 1 MeV gammas will be clearly separated from alphas because they will not produce a large cloud of charge, just a small cluster of Compton electrons. _
• Figure 4 Picture of an exposure of the DECam CCD to cosmic rays. Muons, alphas, electrons and low energy photons can be distinguished by their signatures on the CCD [6] .
• Neutron imaging the direct production of images by transmitting a beam of thermal neutrons through an object, could benefit from this high resolution tracking of a-particles.
• the resolution for neutron imaging application has typically two components: the beam collimation and the detector.
• the detector corresponds to an active medium, such as a scintillator, that converts the thermal neutrons into photons or other charged particles of higher energy. These particles are projected into the detector that produces the image.
• a boron-coated CCD as a detector, ⁇ -particles would be produced by the thermal neutrons, achieving resolutions of only a few microns for the imaging, as illustrated in Figure 5.
• Neutron imaging is performed by transmitting a beam of thermal neutrons through an object onto a thin film of Boron-10 deposited on a CCD.
• a powdered metal, metal/ceramic blend, or polymer is accelerated by compressed air through a supersonic nozzle and is sprayed on the surface to be coated.
• the hardness, porosity, and thickness of deposited coatings can be controlled by adjustments to the air pressure, pre-heater, and nozzle. Spraying at supersonic velocity forms a strong bond without the undesirable side effects inherent in _
• Topic 21c Adaption of CCDs for Neutron Detection and Imaging MuPlus Inc. conventional thermal methods.
• the cold gas dynamic spray method is that the application equipment and deposited coatings have no limitations inherent in other thermal coating methods and without the complexity of detonation or exotic gas inherent in other deposition methods.
• FIG. 1 Schematic of the application of cold gas dynamic spray.
• the NSF has appreciated the importance and potential of neutron imaging by devoting a center to it.
• High resolution imaging by neutrons can complement current photon and electron interrogation methods by providing resolution in areas where these technologies fall short as illustrated above.
• Setup test stand for CCD neutron imager This includes a vacuum vessel and vacuum
• Topic 21c Adaption of CCDs for Neutron Detection and Imaging MuPlus Inc. holder, data cables, a cold finger to cool CCDs to -100c using a cyro-cooler. Setup preamp/amplifier and data acquisition system along with associated power supplies.
• MuPlus, Inc. The direction of the project is the responsibility of the company and the PI.
• the project activities include test development and plans for the CCD coatings and test set-up.
• FNAL Dr. Juan Estrada will be responsible for the FNAL sub grant. g. Phase I Performance Schedule
• Muons, Inc. is a member of the Large Area Fast Photo-Detectors (LAPD) Collaboration, and have been involved in pico- second fast time of flight counters in previous SBIR/STTPv contracts.
• LAPD Large Area Fast Photo-Detectors
• Our parent company is also involved in a variety of projects involving superconducting RF, for which neutron imaging may prove a valuable to in enhancing cavity performance.
• FNAL subgrant Principal Investigator Juan Estrada is a Fermilab scientist at the Center for Particle Astrophysics. He is the principal scientist building and testing imaging sensors for the Dark Energy Camera. He has set himself apart by using the same technology in a side project to search for dark matter called DAMIC for Dark Matter in CCDs. He had worked on cosmology as an undergraduate in Argentina, and started at Fermilab as a student from the University of Rochester working on the DZero experiment. He eventually earned a Wilson Episode. He is a 2010 recipient of the Presidential Early Career Award for Engineers and Engineers for his innovation in CCDs that resulted in the best detector in the world for spotting low-mass dark matter particles.
• Estrada builds charge-coupled devices, the same type of imaging sensors found in digital cameras, for the 570-megapixel Dark Energy Camera. These CCDs are specifically designed to capture the light that reaches Earth from extremely distant galaxies and supernovae. The Dark Energy Survey will use data from the camera to search of signs of dark energy, which scientists theorize affects the evolving shape of the universe. _
• MuPlus Inc. currently shares facilities with Muons, Inc. This includes a building of approximately 4000 square feet of floor space in Batavia, Illinois, a short drive from Fermilab, which is used as office space, conference rooms, workshop area, and living quarters as needed. We also share office space with Muons, Inc. in Wilson Hall at Fermilab (Batavia, IL) and in the ARC building at Jefferson Lab (Newport News, VA). We have several high-performance personal computers and workstations with high-speed net access and sufficient computing power to perform simulations and CAD work.
• Fermilab is located on a site of 6800 acres in Batavia, Illinois. It needs no introduction here. For this particular project, it has all the necessary facilities and equipment for testing CCDs in Phase I, and for a prototype CCD imaging array construction and tests for Phase II. In particular, hundreds of individual CCDs are available left over from the DECam project, some configured into instrumented arrays or engineering "packages" which will be good for deposition tests. k. Consultants and Subcontractors

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• 2013
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