摘要:

Gamma Resonance Technology provides the combined capability of absorption and fluorescence in the simultaneous detection and imaging of multiple elements for identification of contraband and total density for imaging of contents. This method of scanning is unique in its ability to provide imaging by element coincident with total density imaging. In addition it includes both high resolution and high penetration without induced radioactivity as is encountered with neutron techniques. The scanning beam dynamics and geometry allow for system configurations that provide 3‐D tomographic, multiple projection, single sided imaging and standoff identification. This technique has been demonstrated for high explosives including thin sheet containing nitrogen and present system design is to include nitrogen, oxygen, chlorine and other elements of interest. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1619861

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The neutron backscattering technique may be applied to search for non‐metallic land mines in relatively dry sandy soils. A novel, ergonomic detector system has been constructed. Tests with real land mines in a realistic environment show that anti‐tank mines can reliably be found, but that anti‐personnel mines may escape detection. The performance could improve when an image of the mine signal could be obtained. One approach is to use an array of position sensitive3He detectors placed close to the soil. If a pulsed neutron generator is used further improvement could be reached by applying a time window on the neutron transit time. The possibilities of neutron backscattering imaging systems are investigated using Monte Carlo simulations with GEANT‐4. A neutron backscattering imaging device with a 2D sensitive detection plane is currently under development. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1619862

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

NELIS (Neutron ELemental Inspection System) is currently being developed to inspect cargo pallets for illicit drugs. NELIS must be used in conjunction with an x‐ray imaging system to optimize the inspection capabilities at ports of entry. Pulsed fast‐thermal neutron analysis is utilized to measure the major and minor chemical elements in a non‐destructive and non‐intrusive manner. Fourteen‐MeV neutrons produced with a pulsed d‐T neutron generator are the interrogating particles. NELIS analyzes the characteristic gamma rays emitted from the object that are produced by nuclear reactions from fast and thermal neutrons. These gamma rays have different energies for each chemical element, and act as their fingerprints. Since the elemental composition of illicit drugs is quite different from that of innocuous materials, drugs hidden in pallets are identified through the comparison of expected and measured elemental composition and ratios. Results of tests of the system will be discussed. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1619863

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A new nondestructive accelerator based x‐ray fluorescence (AXRF) approach has been developed to identify heavy metals in large‐volume samples. Such samples are an important part of the process and waste streams of U.S Department of Energy sites, as well as other industries such as mining and milling. Distributions of heavy metal impurities in these process and waste samples can range from homogeneous to highly inhomogeneous, and non‐destructive assays and imaging that can address both are urgently needed. Our approach is based on using high‐energy, pulsed bremsstrahlung beams (3–6.5 MeV) from small electron accelerators to produce K‐shell atomic fluorescence x‐rays. In addition we exploit pair‐production, Compton scattering and x‐ray transmission measurements from these beams to probe locations of high density and high atomic number. The excellent penetrability of these beams allows assays and images for soil‐like samples at least 15 g/cm2thick, with elemental impurities of atomic number greater than approximately 50. Fluorescence yield of a variety of targets was measured as a function of impurity atomic number, impurity homogeneity, and sample thickness. We report on actual and potential detection limits of heavy metal impurities in a soil matrix for a variety of samples, and on the potential for imaging, using AXRF and these related probes. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1619864

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The Idaho National Engineering and Environmental Laboratory (INEEL) and the Los Alamos National Laboratory (LANL) have performed experiments in La Honda, California and at the Idaho Accelerator Center in Pocatello, Idaho to assess and develop a photonuclear‐based detection system for shielded nuclear materials in cargo containers. The detection system, measuring photonuclear‐related neutron emissions, is planned for integration with the ARACOR Eagle Cargo Container Inspection System (Sunnyvale, CA). The Eagle Inspection system uses a nominal 6‐MeV electron accelerator and operates with safe radiation exposure limits to both container stowaways and to its operators. The INEEL has fabricated custom‐built, helium‐3‐based, neutron detectors for this inspection application and is performing an experimental application assessment. Because the Eagle Inspection system could not be moved to LANL where special nuclear material was available, the response of the Eagle had to be determined indirectly so as to support the development and testing of the detection system. Experiments in California have successfully matched the delayed neutron emission performance of the ARACOR Eagle with that of the transportable INEEL electron accelerator (i.e., the Varitron) and are reported here. A demonstration test is planned at LANL using the Varitron and shielded special nuclear materials within a cargo container. Detector results are providing very useful information regarding the challenges of delayed neutron counting near the photofission threshold energy of 5.5 – 6.0 MeV, are identifying the possible utilization of prompt neutron emissions to allow enhanced signal‐to‐noise measurements, and are showing the overall benefits of using higher electron beam energies. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1619865

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The Los Alamos Neutron Science Center, or LANSCE, is an accelerator‐based national user facility for research in basic and applied science. At present LANSCE has two experimental areas primarily using neutrons generated by 800‐MeV protons striking tungsten target systems. A third area uses the proton beam for radiography. This paper describes the three LANSCE experimental areas, gives highlights of the past operating period, and discusses plans for the future. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1619866

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The self‐extracting cyclotron is a 14MeV multi‐mA H+ machine from which the beam extracts without a deflector. The development of this prototype has started in 1998, and has now reached a point such that IBA considers to use it as a production machine. It is now installed in an irradiation facility and is equipped with two beam lines and two high power target‐system. Beams of more than 1 mA have been extracted and transported to targets Further development is ongoing in order to increase the current on target to at least 2 mA in the coming months. Commercial isotope production will start at the end of this year. This paper will describe the current configuration of the cyclotron and the associated performances. Emphases will be put on reliability and associated problems, beam optics and performances of sub‐systems. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1619867

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

One of the main SCK•CEN research facility, namely BR2, is nowadays arriving at an age of 40 years just like the major materials testing reactors (MTR) in the world and in Europe (i.e. BR2 (B‐Mol), HFR (EU‐Petten), OSIRIS (F‐Saclay), R2 (S‐Studsvik)). The MYRRHA facility in planning has been conceived as potentially replacing BR2 and to be a fast spectrum facility complementary to the thermal spectrum RJH (Re´acteur Jules Horowitz) facility, in planning in France. This situation would give Europe a full research capability in terms of nuclear R&D. Furthermore, the disposal of radioactive wastes resulting from industrial nuclear energy production has still to find a fully satisfactory solution, especially in terms of environmental and social acceptability. Scientists are looking for ways to drastically reduce (by a factor of 100 or more) the radio‐toxicity of the High Level Waste (HLW) to be stored in a deep geological repository. This can be achieved via burning of minor actinides (MA) and to a less extent of long‐lived fission products (LLFP) in Accelerator Driven Systems. The MYRRHA project contribution will be in helping to demonstrate the ADS concept at reasonable power level and the demonstration of the technological feasibility of MA and LLFP transmutation under real conditions. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1619868

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Developed under the auspices of UNESCO, SESAME (Synchrotron light for Experimental Science and Application in the Middle East) will be a major international research centre in the Middle East / Mediterranean region. Most of the applications require hard x‐rays up to 20 keV photons. SESAME will be a 2GeV 3rdGeneration Ligth Source with an emittance of 17 nmrad and 13 places for the installation of insertion devices with a length around 3 meter. The circumference of the machine will be 120m. As injector the 800 MeVBooster Synchrotron will be used with small changes. Furthermore also the BESSY I quadrupoles and sextupoles can be used. In a later stage these new ones will be replaced in order to increase the length of the straight sections and to introduce mini beta sections for the reduction of the beam cross section. At SESAME around 35 &percent; of the circumference can be used for the installation of insertion devices. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1619869

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

240fs 18 MeV low emittance(6 pai mm.mrad) electron beam was generated and its pulse shape was diagnosed by the S‐band laser photocathode RF gun and linac. The maximum charge per bunch was 7 nC. This electron pulse was synchronized with 100fs 0.3TW Ti:Sapphire laser with the timing jitter of 330fs(rms). Recently, the Cu cathode(QE10∧‐4) was replaced by Mg cathode(QE10∧‐3). This system is utilized for radiation chemistry analysis for supercritical water. We have adopted the four diagnostic methods(femtosecond streak camera, coherent transition radiation interferometer, far‐infrared polychromator, fluctuation method) and checked their time‐resolution precisely. Further, we are doing the experiment on laser plasma cathode by 12TW 50fs laser and He gas jet. Laser plasma wakefield acceleration and electron injection via wavebreaking are planned. We have developed a new theory of self‐injection scheme to generate ∼10fs electron pulse. We have already succeeded in observing 40 MeV low emittance electron beam of 14 nC. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1619870

出版商:AIP    

年代:1903

数据来源: AIP