The Germans disagreed, and took up its development. Only after a few hours did exposed skin began to blister, as the vocal cords became raw and the lungs filled with liquid. Affected soldiers died or were rendered medically unfit for months, and often succumbed years or decades later to lung disease. At first the British were outraged at its use, but later they sent supplies of poison gas to their own troops in British India, for use against Afghan tribesmen in the North-West Frontier.
By , one-third of all shells being used in World War I were filled with poison gas. In all, , British soldiers were gassed, along with 70, Americans. Three weeks before the end of the war, the British shelled the 16th Bavarian Reserve Infantry with mustard gas. Between the ages of eleven and seventeen, I was lucky to attend the Perse School in Cambridge, only a mile from the Cavendish Laboratory where much of the early work on atomic physics was conducted. Today, I teach at the University of California, Berkeley, an important site for early work on nuclear physics, and still the managing institution for Los Alamos National Laboratory in New Mexico, where the atomic bomb was developed.
The knowledge to create the most destructive weapons in history was developed by clever men in pleasant surroundings, pushing the analytical power of their Stone Age brains to the limit. In that task, deep-seated human emotions and brilliant science clashed in complex ways. She worked with Hahn in Berlin before being expelled from Germany because she was Jewish, and she refused any part in the development of the American bomb.
But while virtually every physicist who saw the potential for nuclear weapons recoiled in horror, scientific genies which can be weaponized are always difficult to keep in their bottles, and impossible during wartime. By the time Hitler invaded Czechoslovakia in March of , science had advanced to the point that the best physicists in both Europe and America could see how an atomic bomb was scientifically possible.
Soon, many would come to consider it necessary as well. Germany failed to make an atomic bomb by a wide margin, and there is some evidence, controversial to be sure, that Heisenberg and other German physicists had intentionally dragged their heels. He drafted a warning letter, and together with Albert Einstein sent it to President Roosevelt. The Manhattan Project soon followed. The U. But the war with Japan raged on, and the new U. President, Harry Truman, struggled with the power he now controlled.
At A. On September 2, , the Japanese formally surrendered. The genie was out of the bottle. Within months of the end of the war, Edward Teller, a Hungarian who was part of the team that had developed the U. In the Soviet Union, Stalin had authorized work on an atomic bomb as early as , and the Russians were helped initially by lease-lend shipments of uranium and other material from the U. His betrayal is said to have advanced the Soviet work by perhaps eighteen months, and captured German scientists added an extra boost after the war.
Russia exploded her first atomic bomb just four years after the Americans. The British had their atomic bomb by , the French by , and the Chinese in Israel has never confirmed its membership, but is thought to have joined the nuclear club by the late s. The Shoshone Indians of Nevada, before battle, killed a sheep, drained its blood into a length of intestine, buried the draught in the ground to ferment, and then smeared their war arrows with the microbial brew.
This would have guaranteed severe infection and probably death following even a superficial arrow wound. Tularemia is a highly infectious disease leading to a painful death from fever, skin ulcers, and pneumonia. It was the cause of serious epidemics in early civilizations stretching from present-day Cyprus to Iraq, and the historical record suggests that infected sheep and donkeys were driven into enemy lines in order to spread infection. During the French and Indian Wars — , the British very likely gave hostile Indian tribes blankets infected with smallpox, and certainly considered the idea.
Once you have dehumanized your enemy, the evidence is that it matters little which way you kill him. But biological weapons represent a particularly insidious and dangerous form of WMDs. They may lack the immediate gruesome effects of chemical weapons or the sheer destructive power of the atomic bomb. But they are inherently stealthy, potentially lethal on a global scale, and when living infectious organisms are involved, all but uncontrollable.
Both Japan and the U. But although the convention was ratified by nations, it lacked policing capacity and within one year of its passage, the Soviet Union began the largest biological weapons program in history. Vladimir Pasechnick, who would defect to the U. Iraq also ignored the convention and in , just before the First Gulf War, a factory south of Baghdad manufactured 5, liters of botulinum toxin.
The coalition forces had insufficient vaccines to protect their soldiers, and U. As a physician, I must say that I find germ warfare to be particularly loathsome.
There are three possible levels on which it could be waged, each more distressing that the one before. First, a bacterium such as anthrax, which is very stable, could be sprayed or spread around a community. Anyone who inhaled it would come down with a non-specific fever and fatigue, which looks like the onset of flu but, left untreated, leads to fatal pneumonia. An anthrax victim, however, could not infect another person. Second, an infectious agent, such as smallpox, could be used to start an epidemic. Third, a new and terrible disease could be genetically engineered that not only infects, but also avoids detection and resists treatment with our current arsenal of vaccines and antibiotics.
This final scenario is the most chilling of all. The last case of this ancient killer of millions was identified in October in Somalia. Yet the very fact of our medical triumph over smallpox makes it a particularly devastating weapon. The virus is highly infectious; causes severe, painful disease with a high rate of mortality; and unlike HIV, for example, is quite robust, and can persist in the environment for months or years. Unlike most viral diseases, it is possible to halt smallpox infection by vaccination after exposure.
However, the smallpox vaccination must be given within the first forty-eight hours after exposure, and large-scale smallpox vaccination was stopped thirty years ago. A smallpox-based attack now could devastate a large population. But even if an outbreak were quickly contained, it would bring a nation to a halt and be exceedingly frightening and painful. All smallpox samples were supposed to be destroyed following eradication, with the exception of two batches.
One is stored at the U. Many other pox viruses and other infectious agents provided by nature could potentially be used as weapons. But the Frankenstein-like creation of novel germs is perhaps an even greater fear. A lethal virus might be assembled accidentally, as happened in Australia in when an experiment to sterilize rodent pests turned sour. The unintentionally lethal virus killed all the experimental animals, despite attempts at vaccination. And the deliberate quest to make germ warfare more effective by genetically modifying existing bacteria and viruses has already begun.
Sergei Popov, a Russian molecular biologist who worked in the Soviet biological weapons program, developed a microbe with the potential to cause a slow death from multiple sclerosis. We tried to defend our country. Biological agents need not kill to be effective terror weapons. In the case of rodent pest control, thought has been given to using a modified virus that would cause infected female animals to make antibodies against the coat surrounding their own eggs. As a pest control strategy, it would produce a generation of sterile rats. If a similar virus were developed against human beings, it might be years before a slowly emerging epidemic of infertility was even recognized as a deliberate attack.
The nuclear arms race between the United States and the Soviet Union in many ways defined the mid-twentieth century. But in some ways we can learn even more from the nuclear confrontation that has played out on the Indian subcontinent. The disturbing lesson is that the technical and economic barriers to WMD acquisition are steadily dropping. The Manhattan project cost two trillion dollars in the money of the time, and involved an industrial effort as large as the whole of the U. Pakistan managed the same feat as an unstable third-world country with a fraction of the resources.
If Iran and North Korea soon join the nuclear club, it will be in part thanks to nuclear secrets purchased from A. Perhaps most disturbing of all, there are thousands of pounds of high-grade nuclear material still in the former Soviet Union, left over from the cold War. Some is unaccounted for, and much of the rest is poorly secured, vulnerable to purchase or theft by terror groups.
The sarin gas released into the Tokyo subway by the Aum religious sect in , which killed seven people and made 2, ill, was made by a single, poorly qualified biochemist, Seichi Endo. Whether used by nations against their enemies, or by small bands of terrorists bent on causing ever greater fear, there is simply too little we can do to stop WMDs and their effects once they have been constructed. Our best hope of security is to encourage and enforce control, while also redoubling our efforts to understand and counteract the conditions that might lead to their use in the first place.
All life, in fact, at its most fundamental level is about competition for resources. Biology has invented a million ways for plants and animals to compete with each other. A tree may compete for light by growing taller; early mammals competed with dinosaurs by only coming out at night; humans and chimpanzees—especially the males—compete for food, space, and reproductive opportunities by fighting with each other.
Human wars may come wrapped in a veneer of religion or political philosophy, but the battle for resources is usually just below the surface. As we saw earlier, while rapid population growth and massive unemployment in some settings, such as the Gaza Strip, do not cause wars or terrorist attacks by themselves, they certainly make them more likely.
The predisposition for team aggression may be an inherent part of chimpanzee and human makeup, but the degree of competition for resources varies with the situation. For example, it seems that team aggression among chimpanzees is less common in the congo, where there are more forest resources, than in Tanzania, where human encroachment has driven the animals into a limited area of forest. The human migrants who crossed the Bering Strait into the Americas about 15, years ago found a continent filled with large, easy-to-hunt mammals, and among their limited human skeletal remains we find no evidence of violence.
But by about B. A thousand years ago, in the American Southwest, the Anasazi and Fremont peoples were foragers who also grew maize. Some built elaborate cliff dwellings. The study of tree rings demonstrates that the area was subject to some decade-long droughts, and during these times the region seems to have been beset by raids and warfare. The population retreated to high pinnacles on the edges of deep canyons.
They hid small caches of grain in hard to reach places and positioned boulders to roll down on enemy clans. Human skeletons show signs of malnutrition, decapitation, and cut marks on long-bones suggesting cannibalism. Some Rousseauean anthropologists protest that reports of cannibalism represent a racist desire to denigrate other cultures, but the scientific evidence suggests otherwise. Excavating an Anasazi site in the American Southwest dating from a.
Sensitive immunological tests revealed evidence of human muscle protein in the pots; even more convincing, the same tests found evidence of human meat in preserved human feces found at the site. When food is scarce, competition becomes increasingly intense and cannibalism, like team aggression, aids survival. Critics have argued that the archaeological evidence for endemic violence in drought-ridden areas is too scattered and circumstantial to draw strong conclusions. A recent study of environment and warfare in contemporary Africa helps put that criticism to rest.
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Edward Miguel of the University of California, Berkeley, and colleagues Shanker Satyanath and Ernest Sergenti of New York University compared rainfall levels and incidents of civil conflict across the African continent, and found that as one increased, the other declined, with a statistical certainty of 95 percent. Interestingly, the effect was found across many different cultures and irrespective of whether the country was well or poorly governed. Competition for resources has led to violence everywhere we look. When Polynesian seafarers reached Easter Island about 1, to 1, years ago, they landed on a forested island full of flightless birds.
By about years ago, the trees had been cut down, the animals had all been eaten, and the clans, who identified themselves with the curious stone statues that still dot the island, fell to fighting each other. The population plummeted from an estimated 20, to just 2, by the time Europeans arrived in the eighteenth century. Here too we find archeological evidence of cannibalism, which lives on in the oral tradition of the islanders.
Samuels ; A. Snyder Show Abstract. Laser-induced breakdown spectroscopy LIBS is a powerful analytical technique to detect the elemental composition of solids, liquids, and gases in real time. All potassium and sodium containing samples revealed narrow-band, atomic-like emissions assigned to transitions of neutral alkali-metal atoms in accordance with the NIST atomic spectra database. The observed molecular emissions showed strong correlation with FTIR absorption spectra of the investigated materials. Feasibility studies on explosive detection and homeland security applications using a neutron and x-ray combined computed tomography system Author s : V.
Sinha; A. Srivastava; H. Lee ; X. Liu Show Abstract. The successful creation and operation of a neutron and X-ray combined computed tomography NXCT system has been demonstrated by researchers at the Missouri University of Science and Technology. The NXCT system has numerous applications in the field of material characterization and object identification in materials with a mixture of atomic numbers represented.
Presently, the feasibility studies have been performed for explosive detection and homeland security applications, particularly in concealed material detection and determination of the light atomic number materials. These materials cannot be detected using traditional X-ray imaging. The new system has the capability to provide complete structural and compositional information due to the complementary nature of X-ray and neutron interactions with materials.
The design of the NXCT system facilitates simultaneous and instantaneous imaging operation, promising enhanced detection capabilities of explosive materials, low atomic number materials and illicit materials for homeland security applications. In addition, a sample positioning system allowing the user to remotely and automatically manipulate the sample makes the system viable for commercial applications. Several explosives and weapon simulants have been imaged and the results are provided.
The fusion algorithms which combine the data from the neutron and X-ray imaging produce superior images. This paper is a compete overview of the NXCT system for feasibility studies of explosive detection and homeland security applications. The design of the system, operation, algorithm development, and detection schemes are provided.
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This is the first combined neutron and X-ray computed tomography system in operation. Furthermore, the method of fusing neutron and X-ray images together is a new approach which provides high contrast images of the desired object. The system could serve as a standardized tool in nondestructive testing of many applications, especially in explosives detection and homeland security research. A review of sensor data fusion for explosives and weapons detection Author s : Michael C.
Kemp Show Abstract. The combination or fusion of data from multiple complementary sensors can potentially improve system performance in many explosives and weapons detection applications. The motivations for fusion can include improved probability of detection; reduced false alarms; detection of an increased range of threats; higher throughput and better resilience to adversary countermeasures.
This paper presents the conclusions of a study which surveyed a wide range of data fusion techniques and examples of the research, development and practical use of fusion in explosives detection. Whilst data fusion is frequently cited as an opportunity, there are fewer examples of its operational deployment. Blockers to the wider use of data fusion include the difficulty of predicting the performance gains that are likely to be achieved in practice, as well as a number of cost, commercial, integration, test and evaluation issues.
The paper makes a number of recommendations for future research work. A simulation study of detection of weapon of mass destruction based on radar Author s : E. Sharifahmadian; Y. Choi ; S. Latifi Show Abstract. Typical systems used for detection of Weapon of Mass Destruction WMD are based on sensing objects using gamma rays or neutrons. Nonetheless, depending on environmental conditions, current methods for detecting fissile materials have limited distance of effectiveness.
Moreover, radiation related to gamma- rays can be easily shielded. The WB-based method capitalizes on the fact that electromagnetic waves penetrate through different materials at different rates. While low-frequency waves can pass through objects more easily, high-frequency waves have a higher rate of absorption by objects, making the object recognition easier. Measuring the penetration depth allows one to identify the sensed material. During simulation, radar waves and propagation area including free space, and objects in the scene are modeled.
In fact, each material is modeled as a layer with a certain thickness. At start of simulation, a modeled radar wave is radiated toward the layers. At the receiver side, based on the received signals from every layer, each layer can be identified. Simulation is performed using radar signals with different frequencies ranges MHz-GHz and powers to identify different layers. Lemoff Show Abstract. For trace detection, these signal enhancements more than offset the small penetration depth due to DUV absorption.
A key challenge for stand-off sensors is to distinguish explosives, with high confidence, from a myriad of unknown background materials that may have interfering spectral peaks. Due to complex interplay of resonant enhancement, self-absorption and laser penetration depth, significant amplitude variation is observed between corresponding Raman bands with different excitation wavelengths.
These variations with excitation wavelength provide an orthogonal signature that complements the traditional Raman signature to improve specificity relative to single-excitation-wavelength techniques. As part of this effort, we are developing two novel CW DUV lasers, which have potential to be compact, and a compact dual-band high throughput DUV spectrometer, capable of simultaneous detection of Raman spectra in two spectral windows.
We have also developed a highly sensitive algorithm for the detection of explosives under low signal-to-noise situations. Explosives detection using quantum cascade laser spectroscopy Author s : John R. Castro-Suarez ; Yadira S. Pollock; Samuel P. Hernandez-Rivera Show Abstract. An infrared spectroscopy based explosives detection system using a quantum cascade laser QCL as excitation source was used to record mid infrared spectral signals of highly energetic materials HEM deposited on real world substrates such as travel baggage, cardboard and wood.
Various deposition methods including sample smearing, spin coating, spray deposition and partial immersion were evaluated for preparing samples and standards used as part of the study. Chemometrics statistical routines such as principal component analysis PCA regression with various preprocessing steps were applied to the recorded infrared spectra of explosives deposited as trace contaminants on target substrates. The results show that the dispersive infrared vibrational technique investigated using QCL is useful for detection of HEMs in the types of substrates studied.
Explosive vapor detection payload for small robots Author s : Phil J. Stimac; Michael Pettit; John P. Wetzel; John W. Detection of explosive hazards is a critical component of enabling and improving operational mobility and protection of US Forces. The Explosives Hazard Trace Detection EHTD payload is designed for plug-and-play installation and operation on small robotic platforms, addressing critical Army needs for more safely detecting concealed or exposed explosives in areas such as culverts, walls and vehicles.
Tewari ; G. Manoj Kumar; S. Venugopal Rao Show Abstract. We present our initial experimental results from the LIBS studies of pyrazole, 1-nitropyrazole, 3-nitropyrazole, 3,4- dinitropyrazole and 1-methyl- 3,4,5 trinitro pyrazole recorded with femtosecond pulses and performed in argon atmosphere. CN molecular bands in three different spectral regions of nm nm, nm nm and nm nm, C2 swan bands near nm nm, nm— nm and nm nm were observed.
The C peak at The effect of number of nitro groups on the atomic and molecular emission has been evaluated. A gate delay of ns and a gate width of ns were used for collecting the spectra. Models to support active sensing of biological aerosol clouds Author s : Andrea M. Brown ; Jeffrey M. Kalter; Elizabeth C. Corson; Zahra Chaudhry; Nathan T. Boggs; David M. Brown ; Michael E. Thomas ; Christopher C. Carter Show Abstract. Comprehensive models that explain the scattering behavior from the aerosol cloud are needed to understand and predict the scattering signatures of biological aerosols under varying atmospheric conditions and against different aerosol backgrounds.
Elastic signatures are dependent on many parameters of the aerosol cloud, with two major components being the size distribution and refractive index of the aerosols. Understanding water uptake in bioaerosols using laboratory measurements, field tests, and modeling Author s : Zahra Chaudhry; Shanna A. Ratnesar-Shumate; Thomas J. Buckley; Jeffrey M. Kalter; Jerome U. Gilberry; Jonathan P. Eshbaugh; Elizabeth C. Corson; Joshua L. Santarpia; Christopher C. Uptake of water by biological aerosols can impact their physical and chemical characteristics.
The water content in a bioaerosol can affect the backscatter cross-section as measured by LIDAR systems. Better understanding of the water content in controlled-release clouds of bioaerosols can aid in the development of improved standoff detection systems. This study includes three methods to improve understanding of how bioaerosols take up water. The laboratory method measures hygroscopic growth of biological material after it is aerosolized and dried.
Hygroscopicity curves are created as the humidity is increased in small increments to observe the deliquescence point, then the humidity is decreased to observe the efflorescence point. The field component of the study measures particle size distributions of biological material disseminated into a large humidified chamber. The first operated under dry conditions by sampling downstream of desiccant dryers, the second operated under ambient conditions. Relative humidity was measured within the sampling systems to determine the difference in the aerosol water content between the two sampling trains.
The water content of the bioaerosols was calculated from the twin APS units following Khlystov et al. Biological material is measured dried and wet and compared to laboratory curves of the same material. Lastly, theoretical curves are constructed from literature values for components of the bioaerosol material.
Wavelength resolved polarized elastic scatter measurements from micron-sized single particles Author s : Vasanthi Sivaprakasam ; Jozsef Czege; Jay D. Eversole Show Abstract. Such signature patterns may be able to provide particle classification capability, such as, for example, discrimination between man-made and naturally occurring aerosols. If successful, this effort could improve current detection methods for biological warfare BW agent aerosols.
So far, we have demonstrated an experimental arrangement to measure polarization-state resolved, multi-angle, scattering intensities from single aerosol particles on-the-fly. Our novel approach is a radical departure from conventional polarimetric measurement methods, and a key factor is the use of a multiple-order retarder to prepare different polarization states, depending on the wavelength of the incident light. This novel experimental technique uses a supercontinuum light source, an array of optical fibers, an imaging spectrometer and an EMCCD camera to simultaneously acquire wavelength and angle dependent particle light scattering data as a two-dimensional snapshot.
Scientific Principles of Improvised Warfare and Home Defense - Volume 5
Mueller matrix elements were initially measured from individual particles held in an optical trap at nm. Since particles can be stably trapped for long periods hours , we were able to change the optical configuration to acquire multiple Mueller matrix element measurements on a single particle. We have computationally modeled these measurements at specific angles, and the comparison with experimental measurements shows good agreement. Similar measurements have also been made on slowly falling particles, and our current efforts are focused on improving experimental technique sufficiently to make such measurements on flowing particles.
Recent investigations have focused on the improvement of rapid and accurate methods to develop spectroscopic markers of compounds constituting microorganisms that are considered biological threats. Quantum cascade lasers QCL systems have revolutionized many areas of research and development in defense and security applications, including his area of research. Infrared spectroscopy detection based on QCL was employed to acquire mid infrared MIR spectral signatures of Bacillus thuringiensis Bt , Escherichia coli Ec and Staphylococcus epidermidis Se , which were used as biological agent simulants of biothreats.
The experiments were carried out in reflection mode on various substrates such as cardboard, glass, travel baggage, wood and stainless steel. Metaproteomics analyses as diagnostic tool for differentiation of Escherichia coli strains in outbreaks Author s : Rabih E. Jabbour ; James D.
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Wright; Samir V. The secreted proteins of the enterohemorrhagic and enteropathogenic E. We are employing a metaproteomic approach as an effective and complimentary technique to the current genomic based approaches.
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This metaproteomic approach will evaluate the secreted proteins associated with pathogenicity and utilize their signatures as differentiation biomarkers between EHEC and EPEC strains. The result showed that the identified tryptic peptides of the secreted proteins extracted from different EHEC and EPEC growths have difference in their amino acids sequences and could potentially utilized as biomarkers for the studied E. Analysis of extract from EHEC OH4 resulted in identification of a multidrug efflux protein, which belongs to the family of fusion proteins that are responsible of cell transportation.
Experimental peptides identified lies in the region of the HlyD haemolysin secretion protein-D that is responsible for transporting the haemolysin A toxin. The taxonomic results showed strain level classification for the studied strains and distinctive separation among the strains. There are no reported studies addressing the characterization of secreted proteins in various enhanced growth media and utilizing them as biomarkers for strain differentiation.
The results of FY are promising to pursue further experimentation to statistically validate the results and to further explore the impact of environmental conditions on the nature of the secreted biomarkers in various E. Advances in synthetic peptides reagent discovery Author s : Bryn L. Adams; Deborah A.
Sarkes; Amethist S. Finch; Dimitra N. Bacterial display technology offers a number of advantages over competing display technologies e. We have previously shown that discovery of synthetic peptide reagents utilizing bacterial display technology is relatively simple and rapid to make laboratory automation possible. This included extensive study of the protective antigen system of Bacillus anthracis, including development of discovery, characterization, and computational biology capabilities for in-silico optimization.
Although the benefits towards CBD goals are evident, the impact is far-reaching due to our ability to understand and harness peptide interactions that are ultimately extendable to the hybrid biomaterials of the future. In this paper, we describe advances in peptide discovery including, new target systems e. Curioni ; Rico Chandra Show Abstract. To maximize the detection capability for SNM, the prototype will combine detectors for fast and thermal neutrons, as well as for gamma-rays. The key detector technology in the development is high pressure scintillation cells filled with noble gases, as recently developed by ARKTIS.
The project started officially at the beginning of , for a duration of 30 months. The goal of the project is to deliver a fully integrated and field tested prototype of a modular mobile system capable of passively detecting weak or shielded radioactive sources with accuracy higher than currently available systems. We will present the status of the project, preliminary results and future prospects. Nevada Nanotech Systems, Inc. By conducting multiple measurements, the system can provide a more complete characterization of an unknown sample, leading to a more accurate identification.
Positive identifications of threats are communicated using an integrated wireless module. Currently, system development is focused on detection of commercial, military and improvised explosives, radioactive materials, and chemical threats. The system can be configured for a variety of CBRNE applications, including handheld wands and swab-type threat detectors requiring short sample times, and ultra-high sensitivity detectors in which longer sampling times are used.
Here we provide an overview of the system design and operation and present results from preliminary testing. For 50 years, it was assumed that unlike liquid scintillators or organic crystals, plastic scintillators were not able to discriminate fast neutrons from gamma. Probing the gamma-scintillation process in semiconductor nanomaterials using ultrafast transient cathodoluminescence Author s : Jeffrey M. Pietryga; Lazaro A. Klimov ; Richard D. Schaller Show Abstract. Energy-resolving gamma-ray detectors are of particular interest for the detection of illicit radioactive materials at border crossings and other portals because they offer fast, contactless screening that can discriminate between dangerous and benign materials.
Among detector classes, scintillators offer an intriguing balance between cost and performance, but current technologies rely on single-crystal materials that are not scalable to portal-relevant detector sizes.
Thus, there is a recognized need for novel, processible, high-performance scintillating materials or composites. Composites based on semiconductor nanocrystal quantum dots QDs are of interest because of their potentially high gamma-stopping power, high emission quantum yields, and low-cost solution synthesis and processing. Yet the performance of these and other granular nanomaterials has not met expectations. We suggest that this is due to the general lack of insight into the gamma-to-photons transduction process within these inherently more complex materials, which reduces the development and refinement of candidates to simple trial-and-error.
Here, we describe the development of ultrafast transient cathodoluminescence as a unique spectroscopic tool for probing the population of excited states formed within a material during scintillation, and thus determining the major sources of energy loss. We examine how we reached this conclusion, and how this insight defines the characteristics needed in the next generation of scintillating QD composites.
Continuous p-n junction with extremely low leakage current for micro-structured solid-state neutron detector applications Author s : Kuan-Chih Huang ; Rajendra Dahal; James J. Lu; Yaron Danon; Ishwara B. Bhat Show Abstract. Considerable progress has been achieved recently to enhance the thermal neutron detection efficiency of solid-state neutron detectors that incorporate neutron sensitive materials such as 10 B and 6 LiF in Si micro-structured p-n junction diode.
Finally, current density-voltage and pulse height distribution of fabricated devices with 2. Hutcheson; Duane L. Simonson ; Marc Christophersen ; Bernard F. Phlips ; Nicholas A. Pulse shape discrimination PSD is a common method to distinguish between pulses produced by gamma rays and neutrons in scintillator detectors. This technique takes advantage of the property of many scintillators that excitations by recoil protons and electrons produce pulses with different characteristic shapes.
In contrast, plastic scintillator detectors are relatively low-cost, and easily handled and mass-produced. Recent studies have demonstrated efficient PSD in plastic scintillators using a high concentration of fluorescent dyes. To further investigate the PSD properties of such systems, mixed plastic scintillator samples were produced and tested. The addition of up to 30 wt. These plastic scintillators are produced in large diameters up to 4 inches by melt blending directly in a container suitable for in-line detector use. This allows recycling and reuse of materials while varying the compositions.
This strategy also avoids additional sample handling and polishing steps required when using removable molds. In this presentation, results will be presented for different mixed-plastic compositions and compared with known scintillating materials. Madden; Peter F. Legere; Matt Lewis; Mark L. Ryan Show Abstract. Radioactive materials that could be fashioned into a radiation dispersal device typically emit gamma rays, while fissile materials such as uranium and plutonium emit both neutrons and gamma rays via spontaneous or induced fission.
The simultaneous detection of neutrons and gamma rays is a clear indication of the presence of fissile material. The instrument works as a double-scatter telescope, requiring a neutron or gamma ray to undergo an interaction in two detectors to be considered a valid event. While this requirement reduces the detector efficiency, it yields information about the direction and energy of the incident particle, which is then used to reconstruct an image of the emitting source.
Because of this imaging capability background events can be rejected, decreasing the number of events required for high confidence detection and thereby greatly improving its sensitivity. The instrument is optimized for the detection of neutrons with energies from MeV and gamma rays from 0. Images and energy spectra for neutron and gamma rays are reported for several sources including depleted uranium and plutonium.
In addition, the effect of neutron source shielding is investigated. Griffin Show Abstract. Portable LIBS sensor communication bandwidth limitations favor local material classification for low power consumption. Prior publications address the creation of a low mass, low power, robust hardware spectra classifier for a limited set of predetermined materials in an atmospheric matrix. The performance modeling of the control system with an emphasis on further optimization needs addressing. This paper characterizes, from a control system standpoint, the predictor-corrector architecture applied to LIBS data collection.
In addition, the application of this as a material classifier is presented. Updates in the model implemented on a low power multi-core DSP will be presented as well. Performance comparisons to alternative control system structures will be considered. Email or Username. Forgot username?
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