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Cosmic rays and tests of fundamental principles  [PDF]
Luis Gonzalez-Mestres
Physics , 2010, DOI: 10.1016/j.nuclphysbps.2011.03.005
Abstract: It is now widely acknowledged that cosmic rays experiments can test possible new physics directly generated at the Planck scale or at some other fundamental scale. By studying particle properties at energies far beyond the reach of any man-made accelerator, they can yield unique checks of basic principles. A well-known example is provided by possible tests of special relativity at the highest cosmic-ray energies. But other essential ingredients of standard theories can in principle be tested: quantum mechanics, uncertainty principle, energy and momentum conservation, effective space-time dimensions, hamiltonian and lagrangian formalisms, postulates of cosmology, vacuum dynamics and particle propagation, quark and gluon confinement, elementariness of particles... Standard particle physics or string-like patterns may have a composite origin able to manifest itself through specific cosmic-ray signatures. Ultra-high energy cosmic rays, but also cosmic rays at lower energies, are probes of both "conventional" and new Physics. Status, prospects, new ideas, and open questions in the field are discussed. The Post Scriptum shows that several basic features of modern cosmology naturally appear in a SU(2) spinorial description of space-time without any need for matter, relativity or standard gravitation. New possible effects related to the spinorial space-time structure can also be foreseen. Similarly, the existence of spin-1/2 particles can be naturally related to physics beyond Planck scale and to a possible pre-Big Bang era.
Cosmic Ray Radiography of the Damaged Cores of the Fukushima Reactors  [PDF]
Konstantin Borozdin,Steven Greene,Zarija Luki?,Edward Cas Milner,Haruo Miyadera,Christopher Morris,John Perry
Physics , 2012, DOI: 10.1103/PhysRevLett.109.152501
Abstract: The passage of muons through matter is dominated by the Coulomb interaction with electrons and nuclei. The interaction with the electrons leads to continuous energy loss and stopping of the muons. The interaction with nuclei leads to angle diffusion. Two muon imaging methods that use flux attenuation and multiple Coulomb scattering of cosmic-ray muons are being studied as tools for diagnosing the damaged cores of the Fukushima reactors. Here we compare these two methods. We conclude that the scattering method can provide detailed information about the core. Attenuation has low contrast and little sensitivity to the core.
Assessing the Feasibility of Interrogating Nuclear Waste Storage Silos using Cosmic-ray Muons  [PDF]
F. Ambrosino,L. Bonechi,L. Cimmino,R. D'Alessandro,D. G. Ireland,R. Kaiser,D. F. Mahon,N. Mori,P. Noli,G. Saracino,C. Shearer,L. Viliani,G. Yang
Physics , 2014,
Abstract: Muon radiography is a fast growing field in applied scientific research. In recent years, many detector technologies and imaging techniques using the Coulomb scattering and absorption properties of cosmic-ray muons have been developed for the non-destructive assay of various structures across a wide range of applications. This work presents the first results that assess the feasibility of using muons to interrogate waste silos within the UK Nuclear Industry. Two such approaches, using different techniques that exploit each of these properties, have previously been published, and show promising results from both simulation and experimental data for the detection of shielded high-Z materials and density variations from volcanic assay. Both detector systems are based on scintillator and photomultiplier technologies. Results from dedicated simulation studies using both these technologies and image reconstruction techniques are presented for an intermediate-sized nuclear waste storage facility filled with concrete and an array of uranium samples. Both results highlight the potential to identify uranium objects of varying thicknesses greater than 5cm within real-time durations of several weeks. Increased contributions from Coulomb scattering within the concrete of the structure hinder the ability of both approaches to resolve objects of 2cm dimensions even with increased statistics. These results are all dependent on both the position of the objects within the facility and the locations of the detectors. Results for differing thicknesses of concrete, which reflect the unknown composition of the structures under interrogation, are also presented alongside studies performed for a series of data collection durations. It is anticipated that with further research, muon radiography in one, or both of these forms, will play a key role in future industrial applications within the UK Nuclear Industry.
Tests of Galactic Cosmic Ray Source Models  [PDF]
L O'C Drury,D C Ellison,F A Aharonian,E Berezhko,A Bykov,A Decourchelle,R Diehl,G Meynet,E Parizot,J Raymond,S Reynolds,S Spangler
Physics , 2001,
Abstract: This report discusses the possibilities for observational tests of current models and ideas regarding the origin of the Galactic Cosmic Rays using facilities which are already available.
Cosmic Microwave Background Tests of Inflation  [PDF]
Marc Kamionkowski
Physics , 1997, DOI: 10.1016/S0920-5632(98)00489-7
Abstract: Inflation provides a unified paradigm for understanding the isotropy of the cosmic microwave background (CMB), the flatness problem, and the origin of large-scale structure. Although the physics responsible for inflation is not yet well understood, slow-roll inflation generically makes several predictions: a flat Universe, primordial adiabatic density perturbations, and a stochastic gravity-wave background. Inflation further predicts specific relations between the amplitudes and shapes of the spectrum of density perturbations and gravity waves. There are now excellent prospects for testing precisely these predictions with forthcoming CMB temperature and polarization maps. Here I discuss these new CMB tests of inflation.
Power Laws and the Cosmic Ray Energy Spectrum  [PDF]
J. D. Hague,B. R. Becker,M. S. Gold,J. A. J. Matthews
Mathematics , 2006, DOI: 10.1016/j.astropartphys.2007.02.002
Abstract: Two separate statistical tests are applied to the AGASA and preliminary Auger Cosmic Ray Energy spectra in an attempt to find deviation from a pure power-law. The first test is constructed from the probability distribution for the maximum event of a sample drawn from a power-law. The second employs the TP-statistic, a function defined to deviate from zero when the sample deviates from the power-law form, regardless of the value of the power index. The AGASA data show no significant deviation from a power-law when subjected to both tests. Applying these tests to the Auger spectrum suggests deviation from a power-law. However, potentially large systematics on the relative energy scale prevent us from drawing definite conclusions at this time.
Muon radiography for exploration of Mars geology  [PDF]
S. Kedar,H. K. M. Tanaka,C. J. Naudet,C. E. Jones
Geoscientific Instrumentation, Methods and Data Systems (GI) & Discussions (GID) , 2013, DOI: 10.5194/gi-2-157-2013
Abstract: Muon radiography is a technique that uses naturally occurring showers of muons (penetrating particles generated by cosmic rays) to image the interior of large-scale geological structures in much the same way as standard X-ray radiography is used to image the interior of smaller objects. Recent developments and application of the technique to terrestrial volcanoes have demonstrated that a low-power, passive muon detector can peer deep into geological structures up to several kilometers in size, and provide crisp density profile images of their interior at ten meter scale resolution. Preliminary estimates of muon production on Mars indicate that the near horizontal Martian muon flux, which could be used for muon radiography, is as strong or stronger than that on Earth, making the technique suitable for exploration of numerous high priority geological targets on Mars. The high spatial resolution of muon radiography also makes the technique particularly suited for the discovery and delineation of Martian caverns, the most likely planetary environment for biological activity. As a passive imaging technique, muon radiography uses the perpetually present background cosmic ray radiation as the energy source for probing the interior of structures from the surface of the planet. The passive nature of the measurements provides an opportunity for a low power and low data rate instrument for planetary exploration that could operate as a scientifically valuable primary or secondary instrument in a variety of settings, with minimal impact on the mission's other instruments and operation.
Muon radiography for exploration of Mars geology
S. Kedar,H. K. M. Tanaka,C. J. Naudet,C. E. Jones
Geoscientific Instrumentation, Methods and Data Systems Discussions , 2012, DOI: 10.5194/gid-2-829-2012
Abstract: Muon radiography is a technique that uses naturally occurring showers of muons (penetrating particles generated by cosmic rays) to image the interior of large scale geological structures in much the same way as standard X-ray radiography is used to image the interior of smaller objects. Recent developments and application of the technique to terrestrial volcanoes have demonstrated that a low-power, passive muon detector can peer deep into geological structures up to several kilometers in size, and provide crisp density profile images of their interior at ten meter scale resolution. Preliminary estimates of muon production on Mars indicate that the near horizontal Martian muon flux, which could be used for muon radiography, is as strong or stronger than that on Earth, making the technique suitable for exploration of numerous high priority geological targets on Mars. The high spatial resolution of muon radiography also makes the technique particularly suited for the discovery and delineation of Martian caverns, the most likely planetary environment for biological activity. As a passive imaging technique, muon radiography uses the perpetually present background cosmic ray radiation as the energy source for probing the interior of structures from the surface of the planet. The passive nature of the measurements provides an opportunity for a low power and low data rate instrument for planetary exploration that could operate as a scientifically valuable primary or secondary instrument in a variety of settings, with minimal impact on the mission's other instruments and operation.
Evaluation of plasticity and radiopacity of elastic separators by means of traction tests and radiography  [cached]
Danielle Frota Mendes,José Euclides Nascimento,Adriano Francisco de Lucca Facholli,Maurício de Alencar Casa
Dental Press Journal of Orthodontics , 2012,
Abstract: INTRODUCTION: Elastic separators are widely used in the orthodontic clinic, in different sizes and thicknesses. Their function is to promote the separation between the teeth that will receive orthodontic bands, however, when subgingivally lost, they may cause periodontal problems and, ultimately, cause tooth extraction. OBJECTIVE: Concerned not only about their function but also about their properties, this experimental work was performed in order to evaluate, with a clinical perspective, the plasticity and radiopacity of the elastic separators, usually used in orthodontic clinic, through physical traction tests and radiographs. METHODS: Six different brands were analyzed and divided in two groups: extruded separators (American Orthodontics, GH, Morelli Blue and Morelli Green) and modular separators (Abzil, Dentaurum, GAC, Blue Modular Morelli and Green Modular Morelli). The plasticity was evaluated after physical traction tests, stretching the separators to 3 times their initial diameter. While the radiopacity was assessed using x-rays. RESULTS: When stretched to three times their inner diameter (ID), the extruded separators American Orthodontics, GH, Morelli Blue and Morelli Green and the modular ones Dentaurum, Morelli Blue Modular and Morelli Green Modular, presented elastic deformation, recovering their original inner diameter. The modular separators from Abzil and GAC showed permanent plastic deformation. With respect to radiopacity, the Abzil, American Orthodontics, Dentaurum, GAC and GH separators were radiopaque. CONCLUSION: Correlating the results concerning the plasticity and radiopacity, the separators which showed the most satisfactory results on both tests were, among the extruded separators, American Orthodontics and GH, and among the modular separators, GAC and Dentaurum. INTRODU O: os separadores elásticos s o amplamente usados na clínica ortod ntica, em diferentes tamanhos e espessuras. Sua fun o é promover a separa o entre os dentes a serem bandados, mas, quando subgengivalmente perdidos, podem causar problemas periodontais e, em última instancia, a extra o do dente. OBJETIVO: preocupados n o somente com a sua fun o, mas também com as suas propriedades, realizou-se esse trabalho experimental, que objetiva avaliar, com um enfoque clínico, a plasticidade e radiopacidade dos separadores elásticos, comumente utilizados na clínica ortod ntica, por meio de testes físicos de tra o e radiográficos. MéTODOS: analisou-se seis diferentes marcas de separadores elásticos, as quais foram divididas em dois grupos: separadores extrudados (Americ
Tests of Cosmic Censorship in the Ernst Spacetime  [PDF]
Gary T. Horowitz,Harrison J. Sheinblatt
Physics , 1996, DOI: 10.1103/PhysRevD.55.650
Abstract: The Ernst spacetime is a solution of the Einstein-Maxwell equations describing two charged black holes accelerating apart in a uniform electric (or magnetic) field. As the field approaches a critical value, the black hole horizon appears to touch the acceleration horizon. We show that weak cosmic censorship cannot be violated by increasing the field past this critical value: The event horizon remains intact. On the other hand, strong cosmic censorship does appear to be violated in this spacetime: For a certain range of parameters, we find evidence that the inner horizon is classically stable.
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