KiDS+GAMA: cosmology constraints from a joint analysis of cosmic shear, galaxy-galaxy lensing, and angular clustering

Science.gov (United States)

van Uitert, Edo; Joachimi, Benjamin; Joudaki, Shahab; Amon, Alexandra; Heymans, Catherine; Köhlinger, Fabian; Asgari, Marika; Blake, Chris; Choi, Ami; Erben, Thomas; Farrow, Daniel J.; Harnois-Déraps, Joachim; Hildebrandt, Hendrik; Hoekstra, Henk; Kitching, Thomas D.; Klaes, Dominik; Kuijken, Konrad; Merten, Julian; Miller, Lance; Nakajima, Reiko; Schneider, Peter; Valentijn, Edwin; Viola, Massimo

2018-06-01

We present cosmological parameter constraints from a joint analysis of three cosmological probes: the tomographic cosmic shear signal in ˜450 deg2 of data from the Kilo Degree Survey (KiDS), the galaxy-matter cross-correlation signal of galaxies from the Galaxies And Mass Assembly (GAMA) survey determined with KiDS weak lensing, and the angular correlation function of the same GAMA galaxies. We use fast power spectrum estimators that are based on simple integrals over the real-space correlation functions, and show that they are practically unbiased over relevant angular frequency ranges. We test our full pipeline on numerical simulations that are tailored to KiDS and retrieve the input cosmology. By fitting different combinations of power spectra, we demonstrate that the three probes are internally consistent. For all probes combined, we obtain S_8≡ σ _8 √{Ω _m/0.3}=0.800_{-0.027}^{+0.029}, consistent with Planck and the fiducial KiDS-450 cosmic shear correlation function results. Marginalizing over wide priors on the mean of the tomographic redshift distributions yields consistent results for S8 with an increase of 28 {per cent} in the error. The combination of probes results in a 26 per cent reduction in uncertainties of S8 over using the cosmic shear power spectra alone. The main gain from these additional probes comes through their constraining power on nuisance parameters, such as the galaxy intrinsic alignment amplitude or potential shifts in the redshift distributions, which are up to a factor of 2 better constrained compared to using cosmic shear alone, demonstrating the value of large-scale structure probe combination.

Implications for the missing low-mass galaxies (satellites) problem from cosmic shear

Science.gov (United States)

Jimenez, Raul; Verde, Licia; Kitching, Thomas D.

2018-06-01

The number of observed dwarf galaxies, with dark matter mass ≲ 1011 M⊙ in the Milky Way or the Andromeda galaxy does not agree with predictions from the successful ΛCDM paradigm. To alleviate this problem a suppression of dark matter clustering power on very small scales has been conjectured. However, the abundance of dark matter halos outside our immediate neighbourhood (the Local Group) seem to agree with the ΛCDM-expected abundance. Here we connect these problems to observations of weak lensing cosmic shear, pointing out that cosmic shear can make significant statements about the missing satellites problem in a statistical way. As an example and pedagogical application we use recent constraints on small-scales power suppression from measurements of the CFHTLenS data. We find that, on average, in a region of ˜Gpc3 there is no significant small-scale power suppression. This implies that suppression of small-scale power is not a viable solution to the `missing satellites problem' or, alternatively, that on average in this volume there is no `missing satellites problem' for dark matter masses ≳ 5 × 109 M⊙. Further analysis of current and future weak lensing surveys will probe much smaller scales, k > 10h Mpc-1 corresponding roughly to masses M < 109M⊙.

Cosmic shear measurement with maximum likelihood and maximum a posteriori inference

Science.gov (United States)

Hall, Alex; Taylor, Andy

2017-06-01

We investigate the problem of noise bias in maximum likelihood and maximum a posteriori estimators for cosmic shear. We derive the leading and next-to-leading order biases and compute them in the context of galaxy ellipticity measurements, extending previous work on maximum likelihood inference for weak lensing. We show that a large part of the bias on these point estimators can be removed using information already contained in the likelihood when a galaxy model is specified, without the need for external calibration. We test these bias-corrected estimators on simulated galaxy images similar to those expected from planned space-based weak lensing surveys, with promising results. We find that the introduction of an intrinsic shape prior can help with mitigation of noise bias, such that the maximum a posteriori estimate can be made less biased than the maximum likelihood estimate. Second-order terms offer a check on the convergence of the estimators, but are largely subdominant. We show how biases propagate to shear estimates, demonstrating in our simple set-up that shear biases can be reduced by orders of magnitude and potentially to within the requirements of planned space-based surveys at mild signal-to-noise ratio. We find that second-order terms can exhibit significant cancellations at low signal-to-noise ratio when Gaussian noise is assumed, which has implications for inferring the performance of shear-measurement algorithms from simplified simulations. We discuss the viability of our point estimators as tools for lensing inference, arguing that they allow for the robust measurement of ellipticity and shear.

Simulations and imaging algorithm development for a cosmic ray muon tomography system for the detection of special nuclear material in transport containers

International Nuclear Information System (INIS)

Jewett, C.; Anghel, V.N.P.; Armitage, J.; Boudjemline, K.; Botte, J.; Bryman, D.; Bueno, J.; Charles, E.; Cousins, T.; Didsbury, R.; Erhardt, L.; Erlandson, A.; Gallant, G.; Jason, A.; Jonkmans, G.; Liu, Z.; McCall, M.; Noel, S.; Oakham, F.G.; Ong, D.; Stocki, T.; Thompson, M.; Waller, D.

2011-01-01

The Cosmic Ray Inspection and Passive Tomography (CRIPT) collaboration is developing a cosmic ray muon tomography system to identify Special Nuclear Materials (SNM) in cargo containers. In order to gauge the viability of the technique, and to determine the best detector type, GEANT4 was used to simulate the passage of cosmic ray muons through a cargo container. The scattering density estimation (SDE) algorithm was developed and tested with data from these simulations to determine how well it could reconstruct the interior of a container. The simulation results revealed the ability of cosmic ray muon tomography techniques to image spheres of lead-shielded Special Nuclear Materials (SNM), such as uranium or plutonium, in a cargo container, containing a cargo of granite slabs. (author)

Simulations and imaging algorithm development for a cosmic ray muon tomography system for the detection of special nuclear material in transport containers

Energy Technology Data Exchange (ETDEWEB)

Jewett, C.; Anghel, V.N.P. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Armitage, J.; Boudjemline, K.; Botte, J. [Carleton Univ., Dept. of Physics, Ottawa, Ontario (Canada); Bryman, D. [Advanced Applied Physics Solutions, Vancouver, British Columbia (Canada); Univ. of British Columbia, Vancouver, British Columbia (Canada); Bueno, J. [Advanced Applied Physics Solutions, Vancouver, British Columbia (Canada); Charles, E. [Canada Border Services Agency, Ottawa, Ontario (Canada); Cousins, T. [International Safety Research, Ottawa, Ontario (Canada); Didsbury, R. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Erhardt, L. [Defence Research and Development Canada, Ottawa, Ontario (Canada); Erlandson, A. [Carleton Univ., Dept. of Physics, Ottawa, Ontario (Canada); Gallant, G. [Canada Border Services Agency, Ottawa, Ontario (Canada); Jason, A. [Los Alamos National Laboratory, Los Alamos (United States); Jonkmans, G. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Liu, Z. [Advanced Applied Physics Solutions, Vancouver, British Columbia (Canada); Univ. of British Columbia, Vancouver, British Columbia (Canada); McCall, M.; Noel, S. [International Safety Research, Ottawa, Ontario (Canada); Oakham, F.G. [Carleton Univ., Dept. of Physics, Ottawa, Ontario (Canada); TRIUMF, Vancouver, British Columbia, (Canada); Ong, D.; Stocki, T. [Health Canada, Ottawa, Ontario (Canada); Thompson, M. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Waller, D. [Defence Research and Development Canada, Ottawa, Ontario (Canada)

2011-07-01

The Cosmic Ray Inspection and Passive Tomography (CRIPT) collaboration is developing a cosmic ray muon tomography system to identify Special Nuclear Materials (SNM) in cargo containers. In order to gauge the viability of the technique, and to determine the best detector type, GEANT4 was used to simulate the passage of cosmic ray muons through a cargo container. The scattering density estimation (SDE) algorithm was developed and tested with data from these simulations to determine how well it could reconstruct the interior of a container. The simulation results revealed the ability of cosmic ray muon tomography techniques to image spheres of lead-shielded Special Nuclear Materials (SNM), such as uranium or plutonium, in a cargo container, containing a cargo of granite slabs. (author)

Constraining sources of ultrahigh energy cosmic rays and shear acceleration mechanism of particles in relativistic jets

Energy Technology Data Exchange (ETDEWEB)

Liu, Ruoyu

2015-06-10

Ultrahigh energy cosmic rays are extreme energetic particles from outer space. They have aroused great interest among scientists for more than fifty years. However, due to the rarity of the events and complexity of the process of their propagation to Earth, they are still one of the biggest puzzles in modern high energy astrophysics. This dissertation is dedicated to study the origin of ultrahigh energy cosmic rays from various aspects. Firstly, we discuss a possible link between recently discovered sub-PeV/PeV neutrinos and ultrahigh energy cosmic rays. If these two kinds of particles share the same origin, the observation of neutrinos may provide additional and non-trivial constraints on the sources of ultrahigh energy cosmic rays. Secondly, we jointly employ the chemical composition measurement and the arrival directions of ultrahigh energy cosmic rays, and find a robust upper limit for distances of sources of ultrahigh energy cosmic rays above ∝55 EeV, as well as a lower limit for their metallicities. Finally, we study the shear acceleration mechanism in relativistic jets, which is a more efficient mechanism for the acceleration of higher energy particle. We compute the acceleration efficiency and the time-dependent particle energy spectrum, and explore the feature of synchrotron radiation of the accelerated particles. The possible realizations of this mechanism for acceleration of ultrahigh energy cosmic rays in different astrophysical environments is also discussed.

Optimization of GPS water vapor tomography technique with radiosonde and COSMIC historical data

Directory of Open Access Journals (Sweden)

S. Ye

2016-09-01

Full Text Available The near-real-time high spatial resolution of atmospheric water vapor distribution is vital in numerical weather prediction. GPS tomography technique has been proved effectively for three-dimensional water vapor reconstruction. In this study, the tomography processing is optimized in a few aspects by the aid of radiosonde and COSMIC historical data. Firstly, regional tropospheric zenith hydrostatic delay (ZHD models are improved and thus the zenith wet delay (ZWD can be obtained at a higher accuracy. Secondly, the regional conversion factor of converting the ZWD to the precipitable water vapor (PWV is refined. Next, we develop a new method for dividing the tomography grid with an uneven voxel height and a varied water vapor layer top. Finally, we propose a Gaussian exponential vertical interpolation method which can better reflect the vertical variation characteristic of water vapor. GPS datasets collected in Hong Kong in February 2014 are employed to evaluate the optimized tomographic method by contrast with the conventional method. The radiosonde-derived and COSMIC-derived water vapor densities are utilized as references to evaluate the tomographic results. Using radiosonde products as references, the test results obtained from our optimized method indicate that the water vapor density accuracy is improved by 15 and 12 % compared to those derived from the conventional method below the height of 3.75 km and above the height of 3.75 km, respectively. Using the COSMIC products as references, the results indicate that the water vapor density accuracy is improved by 15 and 19 % below 3.75 km and above 3.75 km, respectively.

Internal inspection of reinforced concrete for nuclear structures using shear wave tomography

International Nuclear Information System (INIS)

Scott, David B.

2013-01-01

Highlights: • Aging of reinforced concrete used for worldwide nuclear structures is increasing and necessitating evaluation. • Nondestructive evaluation is a tool for assessing the condition of reinforced concrete of nuclear structures. • Ultrasonic shear wave tomography as a stress wave technique has begun to be utilized for investigation of concrete material. • A study using ultrasonic shear wave tomography indicates anomalies vital to the long-term operation of the structure. • The use of this technique has shown to successfully evaluate the internal state of reinforced concrete members. - Abstract: Reinforced concrete is important for nuclear related structures. Therefore, the integrity of structural members consisting of reinforced concrete is germane to the safe operation and longevity of these facilities. Many issues that reduce the likelihood of safe operation and longevity are not visible on the surface of reinforced concrete material. Therefore, an investigation of reinforced concrete material should include techniques which will allow peering into the concrete member and determining its internal state. The performance of nondestructive evaluations is pursuant to this goal. Some of the categories of nondestructive evaluations are electrochemical, magnetism, ground penetrating radar, and ultrasonic testing. A specific ultrasonic testing technique, namely ultrasonic shear wave tomography, is used to determine presence and extent of voids, honeycombs, cracks perpendicular to the surface, and/or delamination. This technique, and others similar to it, has been utilized in the nuclear industry to determine structural conditions

Development of a novel micro pattern gaseous detector for cosmic ray muon tomography

Science.gov (United States)

Biglietti, M.; Canale, V.; Franchino, S.; Iengo, P.; Iodice, M.; Petrucci, F.

2016-07-01

We propose a novel detector (Thick Groove Detector, TGD) designed for cosmic ray tomography with a spatial resolution of 500 μm, trying to keep the construction procedure as simple as possible and to reduce the operating costs. The TGD belongs to the category of MPGDs with an amplification region less than 1 mm wide formed by alternate anode/cathode microstrips layers at different heights. A first 10×10 cm2 prototype has been built, divided in four sections with different test geometries. We present the construction procedure and the first results in terms of gain and stability. Preliminary studies with cosmic rays are also reported.

Statistical reconstruction for cosmic ray muon tomography.

Science.gov (United States)

Schultz, Larry J; Blanpied, Gary S; Borozdin, Konstantin N; Fraser, Andrew M; Hengartner, Nicolas W; Klimenko, Alexei V; Morris, Christopher L; Orum, Chris; Sossong, Michael J

2007-08-01

Highly penetrating cosmic ray muons constantly shower the earth at a rate of about 1 muon per cm2 per minute. We have developed a technique which exploits the multiple Coulomb scattering of these particles to perform nondestructive inspection without the use of artificial radiation. In prior work [1]-[3], we have described heuristic methods for processing muon data to create reconstructed images. In this paper, we present a maximum likelihood/expectation maximization tomographic reconstruction algorithm designed for the technique. This algorithm borrows much from techniques used in medical imaging, particularly emission tomography, but the statistics of muon scattering dictates differences. We describe the statistical model for multiple scattering, derive the reconstruction algorithm, and present simulated examples. We also propose methods to improve the robustness of the algorithm to experimental errors and events departing from the statistical model.

Cosmological constraint on the light gravitino mass from CMB lensing and cosmic shear

Energy Technology Data Exchange (ETDEWEB)

Osato, Ken; Yoshida, Naoki [Department of Physics, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033 (Japan); Sekiguchi, Toyokazu [University of Helsinki and Helsinki Institute of Physics, P.O. Box 64, FI-00014, Helsinki (Finland); Shirasaki, Masato [National Astronomical Observatory of Japan, Mitaka, Tokyo, 181-8588 (Japan); Kamada, Ayuki, E-mail: ken.osato@utap.phys.s.u-tokyo.ac.jp, E-mail: toyokazu.sekiguchi@gmail.com, E-mail: masato.shirasaki@nao.ac.jp, E-mail: ayuki.kamada@ucr.edu, E-mail: naoki.yoshida@phys.s.u-tokyo.ac.jp [Department of Physics and Astronomy, University of California, Riverside, California 92521 (United States)

2016-06-01

Light gravitinos of mass ∼< O (10) eV are of particular interest in cosmology, offering various baryogenesis scenarios without suffering from the cosmological gravitino problem. The gravitino may contribute considerably to the total matter content of the Universe and affect structure formation from early to present epochs. After the gravitinos decouple from other particles in the early Universe, they free-stream and consequently suppress density fluctuations of (sub-)galactic length scales. Observations of structure at the relevant length-scales can be used to infer or constrain the mass and the abundance of light gravitinos. We derive constraints on the light gravitino mass using the data of cosmic microwave background (CMB) lensing from Planck and of cosmic shear from the Canada France Hawaii Lensing Survey survey, combined with analyses of the primary CMB anisotropies and the signature of baryon acoustic oscillations in galaxy distributions. The obtained constraint on the gravitino mass is m {sub 3/2} < 4.7 eV (95 % C.L.), which is substantially tighter than the previous constraint from clustering analysis of Ly-α forests.

GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles

Directory of Open Access Journals (Sweden)

P. Xia

2013-10-01

Full Text Available Traditionally, balloon-based radiosonde soundings are used to study the spatial distribution of atmospheric water vapour. However, this approach cannot be frequently employed due to its high cost. In contrast, GPS tomography technique can obtain water vapour in a high temporal resolution. In the tomography technique, an iterative or non-iterative reconstruction algorithm is usually utilised to overcome rank deficiency of observation equations for water vapour inversion. However, the single iterative or non-iterative reconstruction algorithm has their limitations. For instance, the iterative reconstruction algorithm requires accurate initial values of water vapour while the non-iterative reconstruction algorithm needs proper constraint conditions. To overcome these drawbacks, we present a combined iterative and non-iterative reconstruction approach for the three-dimensional (3-D water vapour inversion using GPS observations and COSMIC profiles. In this approach, the non-iterative reconstruction algorithm is first used to estimate water vapour density based on a priori water vapour information derived from COSMIC radio occultation data. The estimates are then employed as initial values in the iterative reconstruction algorithm. The largest advantage of this approach is that precise initial values of water vapour density that are essential in the iterative reconstruction algorithm can be obtained. This combined reconstruction algorithm (CRA is evaluated using 10-day GPS observations in Hong Kong and COSMIC profiles. The test results indicate that the water vapor accuracy from CRA is 16 and 14% higher than that of iterative and non-iterative reconstruction approaches, respectively. In addition, the tomography results obtained from the CRA are further validated using radiosonde data. Results indicate that water vapour densities derived from the CRA agree with radiosonde results very well at altitudes above 2.5 km. The average RMS value of their

X-ray tomography investigation of intensive sheared Al–SiC metal matrix composites

Energy Technology Data Exchange (ETDEWEB)

De Giovanni, Mario; Warnett, Jason M.; Williams, Mark A. [WMG, University of Warwick, Coventry CV4 7AL (United Kingdom); Haribabu, Nadendla [BCAST, Brunel University London, Uxbridge UB8 3PH (United Kingdom); Srirangam, Prakash, E-mail: p.srirangam@warwick.ac.uk [WMG, University of Warwick, Coventry CV4 7AL (United Kingdom)

2015-12-15

X-ray computed tomography (XCT) was used to characterise three dimensional internal structure of Al–SiC metal matrix composites. The alloy composite was prepared by casting method with the application of intensive shearing to uniformly disperse SiC particles in the matrix. Visualisation of SiC clusters as well as porosity distribution were evaluated and compared with non-shearing samples. Results showed that the average particle size as well as agglomerate size is smaller in sheared sample compared to conventional cast samples. Further, it was observed that the volume fraction of porosity was reduced by 50% compared to conventional casting, confirming that the intensive shearing helps in deagglomeration of particle clusters and decrease in porosity of Al–SiC metal matrix composites. - Highlights: • XCT was used to visualise 3D internal structure of Al-SiC MMC. • Al-SiC MMC was prepared by casting with the application of intensive shearing. • SiC particles and porosity distribution were evaluated. • Results show shearing deagglomerates particle clusters and reduces porosity in MMC.

Large vessel imaging using cosmic-ray muons

International Nuclear Information System (INIS)

Jenneson, P.M.

2004-01-01

Cosmic-ray muons are assessed for their practical use in the tomographic imaging of the internal composition of large vessels over 2 m in diameter. The technique is based on the attenuation and scattering of cosmic-ray muons passing through a vessel and has advantages over photon-based methods of tomography that it is extendable to object containing high-density materials over many tens of metres. The main disadvantage is the length of time required to produce images of sufficient resolution and hence cosmic ray muon tomography will be most suited to the imaging of large structures whose internal composition is effectively static for the duration of the imaging period. Simulation and theoretical results are presented here which demonstrate the feasibility of cosmic ray muon tomography

Accurate shear measurement with faint sources

International Nuclear Information System (INIS)

Zhang, Jun; Foucaud, Sebastien; Luo, Wentao

2015-01-01

For cosmic shear to become an accurate cosmological probe, systematic errors in the shear measurement method must be unambiguously identified and corrected for. Previous work of this series has demonstrated that cosmic shears can be measured accurately in Fourier space in the presence of background noise and finite pixel size, without assumptions on the morphologies of galaxy and PSF. The remaining major source of error is source Poisson noise, due to the finiteness of source photon number. This problem is particularly important for faint galaxies in space-based weak lensing measurements, and for ground-based images of short exposure times. In this work, we propose a simple and rigorous way of removing the shear bias from the source Poisson noise. Our noise treatment can be generalized for images made of multiple exposures through MultiDrizzle. This is demonstrated with the SDSS and COSMOS/ACS data. With a large ensemble of mock galaxy images of unrestricted morphologies, we show that our shear measurement method can achieve sub-percent level accuracy even for images of signal-to-noise ratio less than 5 in general, making it the most promising technique for cosmic shear measurement in the ongoing and upcoming large scale galaxy surveys

Compensation of shear waves in photoacoustic tomography with layered acoustic media.

Science.gov (United States)

Schoonover, Robert W; Anastasio, Mark A

2011-10-01

An image reconstruction formula is presented for photoacoustic computed tomography that accounts for conversion between longitudinal and shear waves in a planar-layered acoustic medium. We assume the optical absorber that produces the photoacoustic wave field is embedded in a single fluid layer and any elastic solid layers present are separated by one or more fluid layers. The measurement aperture is assumed to be planar. Computer simulation studies are conducted to demonstrate and investigate the proposed reconstruction formula.

Doppler optical coherence tomography imaging of local fluid flow and shear stress within microporous scaffolds

Science.gov (United States)

Jia, Yali; Bagnaninchi, Pierre O.; Yang, Ying; Haj, Alicia El; Hinds, Monica T.; Kirkpatrick, Sean J.; Wang, Ruikang K.

2009-05-01

Establishing a relationship between perfusion rate and fluid shear stress in a 3D cell culture environment is an ongoing and challenging task faced by tissue engineers. We explore Doppler optical coherence tomography (DOCT) as a potential imaging tool for in situ monitoring of local fluid flow profiles inside porous chitosan scaffolds. From the measured fluid flow profiles, the fluid shear stresses are evaluated. We examine the localized fluid flow and shear stress within low- and high-porosity chitosan scaffolds, which are subjected to a constant input flow rate of 0.5 ml.min-1. The DOCT results show that the behavior of the fluid flow and shear stress in micropores is strongly dependent on the micropore interconnectivity, porosity, and size of pores within the scaffold. For low-porosity and high-porosity chitosan scaffolds examined, the measured local fluid flow and shear stress varied from micropore to micropore, with a mean shear stress of 0.49+/-0.3 dyn.cm-2 and 0.38+/-0.2 dyn.cm-2, respectively. In addition, we show that the scaffold's porosity and interconnectivity can be quantified by combining analyses of the 3D structural and flow images obtained from DOCT.

Constraints on the dark matter and dark energy interactions from weak lensing bispectrum tomography

Energy Technology Data Exchange (ETDEWEB)

An, Rui [School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Feng, Chang [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Wang, Bin, E-mail: an_rui@sjtu.edu.cn, E-mail: chang.feng@uci.edu, E-mail: wang_b@sjtu.edu.cn [Center for Gravitation and Cosmology, College of Physical Science and Technology, Yangzhou University, Yangzhou 225009 (China)

2017-10-01

We estimate uncertainties of cosmological parameters for phenomenological interacting dark energy models using weak lensing convergence power spectrum and bispectrum. We focus on the bispectrum tomography and examine how well the weak lensing bispectrum with tomography can constrain the interactions between dark sectors, as well as other cosmological parameters. Employing the Fisher matrix analysis, we forecast parameter uncertainties derived from weak lensing bispectra with a two-bin tomography and place upper bounds on strength of the interactions between the dark sectors. The cosmic shear will be measured from upcoming weak lensing surveys with high sensitivity, thus it enables us to use the higher order correlation functions of weak lensing to constrain the interaction between dark sectors and will potentially provide more stringent results with other observations combined.

Constraining primordial non-Gaussianity with cosmological weak lensing: shear and flexion

International Nuclear Information System (INIS)

Fedeli, C.; Bartelmann, M.; Moscardini, L.

2012-01-01

We examine the cosmological constraining power of future large-scale weak lensing surveys on the model of the ESA planned mission Euclid, with particular reference to primordial non-Gaussianity. Our analysis considers several different estimators of the projected matter power spectrum, based on both shear and flexion. We review the covariance and Fisher matrix for cosmic shear and evaluate those for cosmic flexion and for the cross-correlation between the two. The bounds provided by cosmic shear alone are looser than previously estimated, mainly due to the reduced sky coverage and background number density of sources for the latest Euclid specifications. New constraints for the local bispectrum shape, marginalized over σ 8 , are at the level of Δf NL ∼ 100, with the precise value depending on the exact multipole range that is considered in the analysis. We consider three additional bispectrum shapes, for which the cosmic shear constraints range from Δf NL ∼ 340 (equilateral shape) up to Δf NL ∼ 500 (orthogonal shape). Also, constraints on the level of non-Gaussianity and on the amplitude of the matter power spectrum σ 8 are almost perfectly anti-correlated, except for the orthogonal bispectrum shape for which they are correlated. The competitiveness of cosmic flexion constraints against cosmic shear ones depends by and large on the galaxy intrinsic flexion noise, that is still virtually unconstrained. Adopting the very high value that has been occasionally used in the literature results in the flexion contribution being basically negligible with respect to the shear one, and for realistic configurations the former does not improve significantly the constraining power of the latter. Since the shear shot noise is white, while the flexion one decreases with decreasing scale, by considering high enough multipoles the two contributions have to become comparable. Extending the analysis up to l max = 20,000 cosmic flexion, while being still subdominant

Effects of self-calibration of intrinsic alignment on cosmological parameter constraints from future cosmic shear surveys

International Nuclear Information System (INIS)

Yao, Ji; Ishak, Mustapha; Lin, Weikang; Troxel, Michael

2017-01-01

Intrinsic alignments (IA) of galaxies have been recognized as one of the most serious contaminants to weak lensing. These systematics need to be isolated and mitigated in order for ongoing and future lensing surveys to reach their full potential. The IA self-calibration (SC) method was shown in previous studies to be able to reduce the GI contamination by up to a factor of 10 for the 2-point and 3-point correlations. The SC method does not require the assumption of an IA model in its working and can extract the GI signal from the same photo-z survey offering the possibility to test and understand structure formation scenarios and their relationship to IA models. In this paper, we study the effects of the IA SC mitigation method on the precision and accuracy of cosmological parameter constraints from future cosmic shear surveys LSST, WFIRST and Euclid. We perform analytical and numerical calculations to estimate the loss of precision and the residual bias in the best fit cosmological parameters after the self-calibration is performed. We take into account uncertainties from photometric redshifts and the galaxy bias. We find that the confidence contours are slightly inflated from applying the SC method itself while a significant increase is due to the inclusion of the photo-z uncertainties. The bias of cosmological parameters is reduced from several-σ, when IA is not corrected for, to below 1-σ after SC is applied. These numbers are comparable to those resulting from applying the method of marginalizing over IA model parameters despite the fact that the two methods operate very differently. We conclude that implementing the SC for these future cosmic-shear surveys will not only allow one to efficiently mitigate the GI contaminant but also help to understand their modeling and link to structure formation.

Effects of self-calibration of intrinsic alignment on cosmological parameter constraints from future cosmic shear surveys

Energy Technology Data Exchange (ETDEWEB)

Yao, Ji; Ishak, Mustapha; Lin, Weikang [Department of Physics, The University of Texas at Dallas, Dallas, TX 75080 (United States); Troxel, Michael, E-mail: jxy131230@utdallas.edu, E-mail: mxi054000@utdallas.edu, E-mail: wxl123830@utdallas.edu, E-mail: michael.a.troxel@gmail.com [Department of Physics, Ohio State University, Columbus, OH 43210 (United States)

2017-10-01

Intrinsic alignments (IA) of galaxies have been recognized as one of the most serious contaminants to weak lensing. These systematics need to be isolated and mitigated in order for ongoing and future lensing surveys to reach their full potential. The IA self-calibration (SC) method was shown in previous studies to be able to reduce the GI contamination by up to a factor of 10 for the 2-point and 3-point correlations. The SC method does not require the assumption of an IA model in its working and can extract the GI signal from the same photo-z survey offering the possibility to test and understand structure formation scenarios and their relationship to IA models. In this paper, we study the effects of the IA SC mitigation method on the precision and accuracy of cosmological parameter constraints from future cosmic shear surveys LSST, WFIRST and Euclid. We perform analytical and numerical calculations to estimate the loss of precision and the residual bias in the best fit cosmological parameters after the self-calibration is performed. We take into account uncertainties from photometric redshifts and the galaxy bias. We find that the confidence contours are slightly inflated from applying the SC method itself while a significant increase is due to the inclusion of the photo-z uncertainties. The bias of cosmological parameters is reduced from several-σ, when IA is not corrected for, to below 1-σ after SC is applied. These numbers are comparable to those resulting from applying the method of marginalizing over IA model parameters despite the fact that the two methods operate very differently. We conclude that implementing the SC for these future cosmic-shear surveys will not only allow one to efficiently mitigate the GI contaminant but also help to understand their modeling and link to structure formation.

A Prototype Scintillating Fibre Tracker for the Cosmic-Ray Muon Tomography of Legacy Nuclear Waste Containers

OpenAIRE

Kaiser, R.; Clarkson, A.; Hamilton, D. J.; Hoek, M.; Ireland, D.G.; Johnstone, J.R.; Keri, T.; Lumsden, S.; Mahon, D. F.; McKinnon, B.; Murray, M.; Nutbeam-Tuffs, S.; Shearer, C.; Staines, C.; Yang, G.

2014-01-01

Cosmic-ray muons are highly-penetrative charged particles observed at sea level with a flux of approximately 1 cm−2 min−1. They interact with matter primarily through Coulomb scattering which can be exploited in muon tomography to image objects within industrial nuclear waste containers. This paper presents the prototype scintillating-fibre detector developed for this application at the University of Glasgow. Experimental results taken with test objects are shown in comparison to results from...

Constraining primordial non-Gaussianity with cosmological weak lensing: shear and flexion

Energy Technology Data Exchange (ETDEWEB)

Fedeli, C. [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611-2055 (United States); Bartelmann, M. [Zentrum für Astronomie, Universität Heidelberg, Albert-Überle-Straße 2, 69120 Heidelberg (Germany); Moscardini, L., E-mail: cosimo.fedeli@astro.ufl.edu, E-mail: bartelmann@uni-heidelberg.de, E-mail: lauro.moscardini@unibo.it [Dipartimento di Astronomia, Università di Bologna, Via Ranzani 1, 40127 Bologna (Italy)

2012-10-01

We examine the cosmological constraining power of future large-scale weak lensing surveys on the model of the ESA planned mission Euclid, with particular reference to primordial non-Gaussianity. Our analysis considers several different estimators of the projected matter power spectrum, based on both shear and flexion. We review the covariance and Fisher matrix for cosmic shear and evaluate those for cosmic flexion and for the cross-correlation between the two. The bounds provided by cosmic shear alone are looser than previously estimated, mainly due to the reduced sky coverage and background number density of sources for the latest Euclid specifications. New constraints for the local bispectrum shape, marginalized over σ{sub 8}, are at the level of Δf{sub NL} ∼ 100, with the precise value depending on the exact multipole range that is considered in the analysis. We consider three additional bispectrum shapes, for which the cosmic shear constraints range from Δf{sub NL} ∼ 340 (equilateral shape) up to Δf{sub NL} ∼ 500 (orthogonal shape). Also, constraints on the level of non-Gaussianity and on the amplitude of the matter power spectrum σ{sub 8} are almost perfectly anti-correlated, except for the orthogonal bispectrum shape for which they are correlated. The competitiveness of cosmic flexion constraints against cosmic shear ones depends by and large on the galaxy intrinsic flexion noise, that is still virtually unconstrained. Adopting the very high value that has been occasionally used in the literature results in the flexion contribution being basically negligible with respect to the shear one, and for realistic configurations the former does not improve significantly the constraining power of the latter. Since the shear shot noise is white, while the flexion one decreases with decreasing scale, by considering high enough multipoles the two contributions have to become comparable. Extending the analysis up to l{sub max} = 20,000 cosmic flexion, while

HIERARCHICAL PROBABILISTIC INFERENCE OF COSMIC SHEAR

International Nuclear Information System (INIS)

Schneider, Michael D.; Dawson, William A.; Hogg, David W.; Marshall, Philip J.; Bard, Deborah J.; Meyers, Joshua; Lang, Dustin

2015-01-01

Point estimators for the shearing of galaxy images induced by gravitational lensing involve a complex inverse problem in the presence of noise, pixelization, and model uncertainties. We present a probabilistic forward modeling approach to gravitational lensing inference that has the potential to mitigate the biased inferences in most common point estimators and is practical for upcoming lensing surveys. The first part of our statistical framework requires specification of a likelihood function for the pixel data in an imaging survey given parameterized models for the galaxies in the images. We derive the lensing shear posterior by marginalizing over all intrinsic galaxy properties that contribute to the pixel data (i.e., not limited to galaxy ellipticities) and learn the distributions for the intrinsic galaxy properties via hierarchical inference with a suitably flexible conditional probabilitiy distribution specification. We use importance sampling to separate the modeling of small imaging areas from the global shear inference, thereby rendering our algorithm computationally tractable for large surveys. With simple numerical examples we demonstrate the improvements in accuracy from our importance sampling approach, as well as the significance of the conditional distribution specification for the intrinsic galaxy properties when the data are generated from an unknown number of distinct galaxy populations with different morphological characteristics

3D shear wave velocity structure revealed with ambient noise tomography on a DAS array

Science.gov (United States)

Zeng, X.; Thurber, C. H.; Wang, H. F.; Fratta, D.

2017-12-01

An 8700-m Distributed Acoustic Sensing (DAS) cable was deployed at Brady's Hot Springs, Nevada in March 2016 in a 1.5 by 0.5 km study area. The layout of the DAS array was designed with a zig-zag geometry to obtain relatively uniform areal and varied angular coverage, providing very dense coverage with a one-meter channel spacing. This array continuously recorded signals of a vibroseis truck, earthquakes, and traffic noise during the 15-day deployment. As shown in a previous study (Zeng et al., 2017), ambient noise tomography can be applied to DAS continuous records to image shear wave velocity structure in the near surface. To avoid effects of the vibroseis truck operation, only continuous data recorded during the nighttime was used to compute noise cross-correlation functions for channel pairs within a given linear segment. The frequency band of whitening was set at 5 to 15 Hz and the length of the cross-correlation time window was set to 60 second. The phase velocities were determined using the multichannel analysis of surface waves (MASW) methodology. The phase velocity dispersion curve was then used to invert for shear wave velocity profiles. A preliminarily velocity model at Brady's Hot Springs (Lawrence Livermore National Laboratory, 2015) was used as the starting model and the sensitivity kernels of Rayleigh wave group and phase velocities were computed with this model. As the sensitivity kernel shows, shear wave velocity in the top 200 m can be constrained with Rayleigh wave group and phase velocities in our frequency band. With the picked phase velocity data, the shear wave velocity structure can be obtained via Occam's inversion (Constable et al., 1987; Lai 1998). Shear wave velocity gradually increases with depth and it is generally faster than the Lawrence Livermore National Laboratory (2015) model. Furthermore, that model has limiting constraints at shallow depth. The strong spatial variation is interpreted to reflect the different sediments and

Measurement of shear-induced diffusion of red blood cells using dynamic light scattering-optical coherence tomography

Science.gov (United States)

Tang, Jianbo; Erdener, Sefik Evren; Li, Baoqiang; Fu, Buyin; Sakadzic, Sava; Carp, Stefan A.; Lee, Jonghwan; Boas, David A.

2018-02-01

Dynamic Light Scattering-Optical Coherence Tomography (DLS-OCT) takes the advantages of using DLS to measure particle flow and diffusion within an OCT resolution-constrained 3D volume, enabling the simultaneous measurements of absolute RBC velocity and diffusion coefficient with high spatial resolution. In this work, we applied DLS-OCT to measure both RBC velocity and the shear-induced diffusion coefficient within penetrating venules of the somatosensory cortex of anesthetized mice. Blood flow laminar profile measurements indicate a blunted laminar flow profile, and the degree of blunting decreases with increasing vessel diameter. The measured shear-induced diffusion coefficient was proportional to the flow shear rate with a magnitude of 0.1 to 0.5 × 10-6 mm2 . These results provide important experimental support for the recent theoretical explanation for why DCS is dominantly sensitive to RBC diffusive motion.

Cosmic shear analysis of archival HST/ACS data. I. Comparison of early ACS pure parallel data to the HST/GEMS survey

Science.gov (United States)

Schrabback, T.; Erben, T.; Simon, P.; Miralles, J.-M.; Schneider, P.; Heymans, C.; Eifler, T.; Fosbury, R. A. E.; Freudling, W.; Hetterscheidt, M.; Hildebrandt, H.; Pirzkal, N.

2007-06-01

Context: This is the first paper of a series describing our measurement of weak lensing by large-scale structure, also termed “cosmic shear”, using archival observations from the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST). Aims: In this work we present results from a pilot study testing the capabilities of the ACS for cosmic shear measurements with early parallel observations and presenting a re-analysis of HST/ACS data from the GEMS survey and the GOODS observations of the Chandra Deep Field South (CDFS). Methods: We describe the data reduction and, in particular, a new correction scheme for the time-dependent ACS point-spread-function (PSF) based on observations of stellar fields. This is currently the only technique which takes the full time variation of the PSF between individual ACS exposures into account. We estimate that our PSF correction scheme reduces the systematic contribution to the shear correlation functions due to PSF distortions to MUSIC sample, we determine a local single field estimate for the mass power spectrum normalisation σ8, CDFS=0.52+0.11-0.15 (stat) ± 0.07(sys) (68% confidence assuming Gaussian cosmic variance) at a fixed matter density Ω_m=0.3 for a ΛCDM cosmology marginalising over the uncertainty of the Hubble parameter and the redshift distribution. We interpret this exceptionally low estimate to be due to a local under-density of the foreground structures in the CDFS. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archives at the Space Telescope European Coordinating Facility and the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Finite frequency shear wave splitting tomography: a model space search approach

Science.gov (United States)

Mondal, P.; Long, M. D.

2017-12-01

Observations of seismic anisotropy provide key constraints on past and present mantle deformation. A common method for upper mantle anisotropy is to measure shear wave splitting parameters (delay time and fast direction). However, the interpretation is not straightforward, because splitting measurements represent an integration of structure along the ray path. A tomographic approach that allows for localization of anisotropy is desirable; however, tomographic inversion for anisotropic structure is a daunting task, since 21 parameters are needed to describe general anisotropy. Such a large parameter space does not allow a straightforward application of tomographic inversion. Building on previous work on finite frequency shear wave splitting tomography, this study aims to develop a framework for SKS splitting tomography with a new parameterization of anisotropy and a model space search approach. We reparameterize the full elastic tensor, reducing the number of parameters to three (a measure of strength based on symmetry considerations for olivine, plus the dip and azimuth of the fast symmetry axis). We compute Born-approximation finite frequency sensitivity kernels relating model perturbations to splitting intensity observations. The strong dependence of the sensitivity kernels on the starting anisotropic model, and thus the strong non-linearity of the inverse problem, makes a linearized inversion infeasible. Therefore, we implement a Markov Chain Monte Carlo technique in the inversion procedure. We have performed tests with synthetic data sets to evaluate computational costs and infer the resolving power of our algorithm for synthetic models with multiple anisotropic layers. Our technique can resolve anisotropic parameters on length scales of ˜50 km for realistic station and event configurations for dense broadband experiments. We are proceeding towards applications to real data sets, with an initial focus on the High Lava Plains of Oregon.

Design and operation of a field telescope for cosmic ray geophysical tomography

Directory of Open Access Journals (Sweden)

N. Lesparre

2012-04-01

Full Text Available The cosmic ray muon tomography gives an access to the density structure of geological targets. In the present article we describe a muon telescope adapted to harsh environmental conditions. In particular the design optimizes the total weight and power consumption to ease the deployment and increase the autonomy of the detector. The muon telescopes consist of at least two scintillator detection matrices readout by photosensors via optical fibres. Two photosensor options have been studied. The baseline option foresees one multianode photomultiplier (MAPM per matrix. A second option using one multipixel photon counter (MPPC per bar is under development. The readout electronics and data acquisition system developed for both options are detailed. We present a first data set acquired in open-sky conditions compared with the muon flux detected across geological objects.

Prediction of intramuscular fat content and shear force in Texel lamb loins using combinations of different X-ray computed tomography (CT) scanning techniques.

Science.gov (United States)

Clelland, N; Bunger, L; McLean, K A; Knott, S; Matthews, K R; Lambe, N R

2018-06-01

Computed tomography (CT) parameters, including spiral computed tomography scanning (SCTS) parameters, intramuscular fat (IMF) and mechanically measured shear force were derived from two previously published studies. Purebred Texel (n = 377) of both sexes, females (n = 206) and intact males (n = 171) were used to investigate the prediction of IMF and shear force in the loin. Two and three dimensional CT density information was available. Accuracies in the prediction of shear force and IMF ranged from R 2 0.02 to R 2 0.13 and R 2 0.51 to R 2 0.71 respectively, using combinations of SCTS and CT scan information. The prediction of mechanical shear force could not be achieved at an acceptable level of accuracy employing SCTS information. However, the prediction of IMF in the loin employing information from SCTS and additional information from standard CT scans was successful, providing evidence that the prediction of IMF and related meat eating quality (MEQ) traits for Texel lambs in vivo can be achieved. Copyright © 2018 Elsevier Ltd. All rights reserved.

Shear-induced diffusion of red blood cells measured with dynamic light scattering-optical coherence tomography.

Science.gov (United States)

Tang, Jianbo; Erdener, Sefik Evren; Li, Baoqiang; Fu, Buyin; Sakadzic, Sava; Carp, Stefan A; Lee, Jonghwan; Boas, David A

2018-02-01

Quantitative measurements of intravascular microscopic dynamics, such as absolute blood flow velocity, shear stress and the diffusion coefficient of red blood cells (RBCs), are fundamental in understanding the blood flow behavior within the microcirculation, and for understanding why diffuse correlation spectroscopy (DCS) measurements of blood flow are dominantly sensitive to the diffusive motion of RBCs. Dynamic light scattering-optical coherence tomography (DLS-OCT) takes the advantages of using DLS to measure particle flow and diffusion within an OCT resolution-constrained three-dimensional volume, enabling the simultaneous measurements of absolute RBC velocity and diffusion coefficient with high spatial resolution. In this work, we applied DLS-OCT to measure both RBC velocity and the shear-induced diffusion coefficient within penetrating venules of the somatosensory cortex of anesthetized mice. Blood flow laminar profile measurements indicate a blunted laminar flow profile and the degree of blunting decreases with increasing vessel diameter. The measured shear-induced diffusion coefficient was proportional to the flow shear rate with a magnitude of ~0.1 to 0.5 × 10 -6  mm 2 . These results provide important experimental support for the recent theoretical explanation for why DCS is dominantly sensitive to RBC diffusive motion. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Prototype Scintillating-Fibre Tracker for the Cosmic-ray Muon Tomography of Legacy Nuclear Waste Containers

Science.gov (United States)

Kaiser, R.; Clarkson, A.; Hamilton, D. J.; Hoek, M.; Ireland, D. G.; Johnston, J. R.; Keri, T.; Lumsden, S.; Mahon, D. F.; McKinnon, B.; Murray, M.; Nutbeam-Tuffs, S.; Shearer, C.; Staines, C.; Yang, G.; Zimmerman, C.

2014-03-01

Cosmic-ray muons are highly-penetrative charged particles observed at sea level with a flux of approximately 1 cm-2 min-1. They interact with matter primarily through Coulomb scattering which can be exploited in muon tomography to image objects within industrial nuclear waste containers. This paper presents the prototype scintillating-fibre detector developed for this application at the University of Glasgow. Experimental results taken with test objects are shown in comparison to results from GEANT4 simulations. These results verify the simulation and show discrimination between the low, medium and high-Z materials imaged.

Relativistic transport theory for cosmic-rays

International Nuclear Information System (INIS)

Webb, G.M.

1985-01-01

Various aspects of the transport of cosmic-rays in a relativistically moving magnetized plasma supporting a spectrum of hydromagnetic waves that scatter the cosmic-rays are presented. A local Lorentz frame moving with the waves or turbulence scattering the cosmic-rays is used to specify the individual particle momentum. The comoving frame is in general a noninertial frame in which the observer's volume element is expanding and shearing, geometric energy change terms appear in the cosmic-ray transport equation which consist of the relativistic generalization of the adiabatic deceleration term and a further term involving the acceleration vector of the scatterers. A relativistic version of the pitch angle evolution equation, including the effects of adiabatic focussing, pitch angle scattering, and energy changes is presented

Tomographic-spectral approach for dark matter detection in the cross-correlation between cosmic shear and diffuse γ-ray emission

International Nuclear Information System (INIS)

Camera, S.; Fornasa, M.; Fornengo, N.; Regis, M.

2015-01-01

We recently proposed to cross-correlate the diffuse extragalactic γ-ray background with the gravitational lensing signal of cosmic shear. This represents a novel and promising strategy to search for annihilating or decaying particle dark matter (DM) candidates. In the present work, we demonstrate the potential of a tomographic-spectral approach: measuring the cross-correlation in separate bins of redshift and energy significantly improves the sensitivity to a DM signal. Indeed, the technique proposed here takes advantage of the different scaling of the astrophysical and DM components with redshift and, simultaneously of their different energy spectra and different angular extensions. The sensitivity to a particle DM signal is extremely promising even when the DM-induced emission is quite faint. We first quantify the prospects of detecting DM by cross-correlating the Fermi Large Area Telescope (LAT) diffuse γ-ray background with the cosmic shear expected from the Dark Energy Survey. Under the hypothesis of a significant subhalo boost, such a measurement can deliver a 5σ detection of DM, if the DM particle is lighter than 300 GeV and has a thermal annihilation rate. We then forecast the capability of the European Space Agency Euclid satellite (whose launch is planned for 2020), in combination with an hypothetical future γ-ray detector with slightly improved specifications compared to current telescopes. We predict that the cross-correlation of their data will allow a measurement of the DM mass with an uncertainty of a factor of 1.5–2, even for moderate subhalo boosts, for DM masses up to few hundreds of GeV and thermal annihilation rates

Tomographic-spectral approach for dark matter detection in the cross-correlation between cosmic shear and diffuse γ-ray emission

Energy Technology Data Exchange (ETDEWEB)

Camera, S. [Jodrell Bank Centre for Astrophysics, The University of Manchester, Alan Turing Building, Oxford Road, Manchester M13 9PL (United Kingdom); Fornasa, M. [School of Physics and Astronomy, University of Nottingham, University Campus, Nottingham NG7 2RD (United Kingdom); Fornengo, N.; Regis, M., E-mail: stefano.camera@manchester.ac.uk, E-mail: fornasam@gmail.com, E-mail: fornengo@to.infn.it, E-mail: regis@to.infn.it [Dipartimento di Fisica, Università di Torino, Via P. Giuria 1, 10125 Torino (Italy)

2015-06-01

We recently proposed to cross-correlate the diffuse extragalactic γ-ray background with the gravitational lensing signal of cosmic shear. This represents a novel and promising strategy to search for annihilating or decaying particle dark matter (DM) candidates. In the present work, we demonstrate the potential of a tomographic-spectral approach: measuring the cross-correlation in separate bins of redshift and energy significantly improves the sensitivity to a DM signal. Indeed, the technique proposed here takes advantage of the different scaling of the astrophysical and DM components with redshift and, simultaneously of their different energy spectra and different angular extensions. The sensitivity to a particle DM signal is extremely promising even when the DM-induced emission is quite faint. We first quantify the prospects of detecting DM by cross-correlating the Fermi Large Area Telescope (LAT) diffuse γ-ray background with the cosmic shear expected from the Dark Energy Survey. Under the hypothesis of a significant subhalo boost, such a measurement can deliver a 5σ detection of DM, if the DM particle is lighter than 300 GeV and has a thermal annihilation rate. We then forecast the capability of the European Space Agency Euclid satellite (whose launch is planned for 2020), in combination with an hypothetical future γ-ray detector with slightly improved specifications compared to current telescopes. We predict that the cross-correlation of their data will allow a measurement of the DM mass with an uncertainty of a factor of 1.5–2, even for moderate subhalo boosts, for DM masses up to few hundreds of GeV and thermal annihilation rates.

Tomographic-spectral approach for dark matter detection in the cross-correlation between cosmic shear and diffuse γ-ray emission

Science.gov (United States)

Camera, S.; Fornasa, M.; Fornengo, N.; Regis, M.

2015-06-01

We recently proposed to cross-correlate the diffuse extragalactic γ-ray background with the gravitational lensing signal of cosmic shear. This represents a novel and promising strategy to search for annihilating or decaying particle dark matter (DM) candidates. In the present work, we demonstrate the potential of a tomographic-spectral approach: measuring the cross-correlation in separate bins of redshift and energy significantly improves the sensitivity to a DM signal. Indeed, the technique proposed here takes advantage of the different scaling of the astrophysical and DM components with redshift and, simultaneously of their different energy spectra and different angular extensions. The sensitivity to a particle DM signal is extremely promising even when the DM-induced emission is quite faint. We first quantify the prospects of detecting DM by cross-correlating the Fermi Large Area Telescope (LAT) diffuse γ-ray background with the cosmic shear expected from the Dark Energy Survey. Under the hypothesis of a significant subhalo boost, such a measurement can deliver a 5σ detection of DM, if the DM particle is lighter than 300 GeV and has a thermal annihilation rate. We then forecast the capability of the European Space Agency Euclid satellite (whose launch is planned for 2020), in combination with an hypothetical future γ-ray detector with slightly improved specifications compared to current telescopes. We predict that the cross-correlation of their data will allow a measurement of the DM mass with an uncertainty of a factor of 1.5-2, even for moderate subhalo boosts, for DM masses up to few hundreds of GeV and thermal annihilation rates.

Clusters and the Cosmic Web

NARCIS (Netherlands)

Weygaert, R. van de

2006-01-01

Abstract: We discuss the intimate relationship between the filamentary features and the rare dense compact cluster nodes in this network, via the large scale tidal field going along with them, following the cosmic web theory developed Bond et al. The Megaparsec scale tidal shear pattern is

A Prototype Scintillating-Fibre Tracker for the Cosmic-ray Muon Tomography of Legacy Nuclear Waste Containers

Directory of Open Access Journals (Sweden)

Kaiser R.

2014-03-01

Full Text Available Cosmic-ray muons are highly-penetrative charged particles observed at sea level with a flux of approximately 1 cm−2 min−1. They interact with matter primarily through Coulomb scattering which can be exploited in muon tomography to image objects within industrial nuclear waste containers. This paper presents the prototype scintillating-fibre detector developed for this application at the University of Glasgow. Experimental results taken with test objects are shown in comparison to results from GEANT4 simulations. These results verify the simulation and show discrimination between the low, medium and high-Z materials imaged.

Optical coherence tomography detection of shear wave propagation in inhomogeneous tissue equivalent phantoms and ex-vivo carotid artery samples

Science.gov (United States)

Razani, Marjan; Luk, Timothy W.H.; Mariampillai, Adrian; Siegler, Peter; Kiehl, Tim-Rasmus; Kolios, Michael C.; Yang, Victor X.D.

2014-01-01

In this work, we explored the potential of measuring shear wave propagation using optical coherence elastography (OCE) in an inhomogeneous phantom and carotid artery samples based on a swept-source optical coherence tomography (OCT) system. Shear waves were generated using a piezoelectric transducer transmitting sine-wave bursts of 400 μs duration, applying acoustic radiation force (ARF) to inhomogeneous phantoms and carotid artery samples, synchronized with a swept-source OCT (SS-OCT) imaging system. The phantoms were composed of gelatin and titanium dioxide whereas the carotid artery samples were embedded in gel. Differential OCT phase maps, measured with and without the ARF, detected the microscopic displacement generated by shear wave propagation in these phantoms and samples of different stiffness. We present the technique for calculating tissue mechanical properties by propagating shear waves in inhomogeneous tissue equivalent phantoms and carotid artery samples using the ARF of an ultrasound transducer, and measuring the shear wave speed and its associated properties in the different layers with OCT phase maps. This method lays the foundation for future in-vitro and in-vivo studies of mechanical property measurements of biological tissues such as vascular tissues, where normal and pathological structures may exhibit significant contrast in the shear modulus. PMID:24688822

NEXUS: tracing the cosmic web connection

Science.gov (United States)

Cautun, Marius; van de Weygaert, Rien; Jones, Bernard J. T.

2013-02-01

We introduce the NEXUS algorithm for the identification of cosmic web environments: clusters, filaments, walls and voids. This is a multiscale and automatic morphological analysis tool that identifies all the cosmic structures in a scale free way, without preference for a certain size or shape. We develop the NEXUS method to incorporate the density, tidal field, velocity divergence and velocity shear as tracers of the cosmic web. We also present the NEXUS+ procedure which, taking advantage of a novel filtering of the density in logarithmic space, is very successful at identifying the filament and wall environments in a robust and natural way. To assess the algorithms we apply them to an N-body simulation. We find that all methods correctly identify the most prominent filaments and walls, while there are differences in the detection of the more tenuous structures. In general, the structures traced by the density and tidal fields are clumpier and more rugged than those present in the velocity divergence and velocity shear fields. We find that the NEXUS+ method captures much better the filamentary and wall networks and is successful in detecting even the fainter structures. We also confirm the efficiency of our methods by examining the dark matter particle and halo distributions.

Use of micro-tomography for validation of method to identify interfacial shear strength from tensile tests of short regenerated cellulose fibre composites

DEFF Research Database (Denmark)

Hajlane, A.; Miettinen, A.; Madsen, Bo

2016-01-01

The interfacial shear strength of short regenerated cellulose fibre/polylactide composites was characterized by means of an industry-friendly adhesion test method. The interfacial shear strength was back-calculated from the experimental tensile stress-strain curves of composites by using a micro......-mechanical model. The parameters characterizing the microstructure of the composites, e.g. fibre length and orientation distributions, used as input in the model were obtained by micro-tomography. The investigation was carried out on composites with untreated and surface treated fibres with various fibre weight...

Rayleigh wave group velocity and shear wave velocity structure in the San Francisco Bay region from ambient noise tomography

Science.gov (United States)

Li, Peng; Thurber, Clifford

2018-06-01

We derive new Rayleigh wave group velocity models and a 3-D shear wave velocity model of the upper crust in the San Francisco Bay region using an adaptive grid ambient noise tomography algorithm and 6 months of continuous seismic data from 174 seismic stations from multiple networks. The resolution of the group velocity models is 0.1°-0.2° for short periods (˜3 s) and 0.3°-0.4° for long periods (˜10 s). The new shear wave velocity model of the upper crust reveals a number of important structures. We find distinct velocity contrasts at the Golden Gate segment of the San Andreas Fault, the West Napa Fault, central part of the Hayward Fault and southern part of the Calaveras Fault. Low shear wave velocities are mainly located in Tertiary and Quaternary basins, for instance, La Honda Basin, Livermore Valley and the western and eastern edges of Santa Clara Valley. Low shear wave velocities are also observed at the Sonoma volcanic field. Areas of high shear wave velocity include the Santa Lucia Range, the Gabilan Range and Ben Lomond Plutons, and the Diablo Range, where Franciscan Complex or Silinian rocks are exposed.

Quantitative shear wave imaging optical coherence tomography for noncontact mechanical characterization of myocardium

Science.gov (United States)

Wang, Shang; Lopez, Andrew L.; Morikawa, Yuka; Tao, Ge; Li, Jiasong; Larina, Irina V.; Martin, James F.; Larin, Kirill V.

2015-03-01

Optical coherence elastography (OCE) is an emerging low-coherence imaging technique that provides noninvasive assessment of tissue biomechanics with high spatial resolution. Among various OCE methods, the capability of quantitative measurement of tissue elasticity is of great importance for tissue characterization and pathology detection across different samples. Here we report a quantitative OCE technique, termed quantitative shear wave imaging optical coherence tomography (Q-SWI-OCT), which enables noncontact measurement of tissue Young's modulus based on the ultra-fast imaging of the shear wave propagation inside the sample. A focused air-puff device is used to interrogate the tissue with a low-pressure short-duration air stream that stimulates a localized displacement with the scale at micron level. The propagation of this tissue deformation in the form of shear wave is captured by a phase-sensitive OCT system running with the scan of the M-mode imaging over the path of the wave propagation. The temporal characteristics of the shear wave is quantified based on the cross-correlation of the tissue deformation profiles at all the measurement locations, and linear regression is utilized to fit the data plotted in the domain of time delay versus wave propagation distance. The wave group velocity is thus calculated, which results in the quantitative measurement of the Young's modulus. As the feasibility demonstration, experiments are performed on tissuemimicking phantoms with different agar concentrations and the quantified elasticity values with Q-SWI-OCT agree well with the uniaxial compression tests. For functional characterization of myocardium with this OCE technique, we perform our pilot experiments on ex vivo mouse cardiac muscle tissues with two studies, including 1) elasticity difference of cardiac muscle under relaxation and contract conditions and 2) mechanical heterogeneity of the heart introduced by the muscle fiber orientation. Our results suggest the

Performance of a Drift Chamber Candidate for a Cosmic Muon Tomography System

Energy Technology Data Exchange (ETDEWEB)

Anghel, V.; Jewett, C.; Jonkmans, G.; Thompson, M. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Armitage, J.; Botte, J.; Boudjemline, K.; Erlandson, A.; Oakham, G. [Ottawa-Carleton Institute for Physics, Department of Physics, Carleton University, Ottawa, Ontario (Canada); Bueno, J.; Bryman, D.; Liu, Z. [Advanced Applied Physics Solutions, Vancouver, British Columbia (Canada); Charles, E.; Gallant, G. [Canada Border Services Agency, Ottawa, Ontario (Canada); Cousins, T.; Noel, S. [International Safety Research, Ottawa, Ontario (Canada); Drouin, P.-L.; Waller, D. [Defence Research and Development Canada, Ottawa, Ontario (Canada); Stocki, T. J. [Health Canada, Ottawa, Ontario (Canada)

2011-12-13

In the last decade, many groups around the world have been exploring different ways to probe transport containers which may contain illicit Special Nuclear Materials such as uranium. The muon tomography technique has been proposed as a cost effective system with an acceptable accuracy. A group of Canadian institutions (see above), funded by Defence Research and Development Canada, is testing different technologies to track the cosmic muons. One candidate is the single wire Drift Chamber. With the capability of a 2D impact position measurement, two detectors will be placed above and two below the object to be probed. In order to achieve a good 3D image quality of the cargo content, a good angular resolution is required. The simulation showed that 1mrad was required implying the spatial resolution of the trackers must be in the range of 1 to 2 mm for 1 m separation. A tracking system using three prototypes has been built and tested. The spatial resolution obtained is 1.7 mm perpendicular to the wire and 3 mm along the wire.

A new method for imaging nuclear threats using cosmic ray muons

OpenAIRE

Morris, C. L.; Bacon, Jeffrey; Borozdin, Konstantin; Miyadera, Haruo; Perry, John; Rose, Evan; Watson, Scott; White, Timothy; Aberle, Derek; Green, J. Andrew; McDuff, George G.; Lukić, Zarija; Milner, Edward C.

2013-01-01

Muon tomography is a technique that uses cosmic ray muons to generate three dimensional images of volumes using information contained in the Coulomb scattering of the muons. Advantages of this technique are the ability of cosmic rays to penetrate significant overburden and the absence of any additional dose delivered to subjects under study above the natural cosmic ray flux. Disadvantages include the relatively long exposure times and poor position resolution and complex algorithms needed for...

In situ monitoring of localized shear stress and fluid flow within developing tissue constructs by Doppler optical coherence tomography

Science.gov (United States)

Jia, Yali; Bagnaninchi, Pierre O.; Wang, Ruikang K.

2008-02-01

Mechanical stimuli can be introduced to three dimensional (3D) cell cultures by use of perfusion bioreactor. Especially in musculoskeletal tissues, shear stress caused by fluid flow generally increase extra-cellular matrix (ECM) production and cell proliferation. The relationship between the shear stress and the tissue development in situ is complicated because of the non-uniform pore distribution within the cell-seeded scaffold. In this study, we firstly demonstrated that Doppler optical coherence tomography (DOCT) is capable of monitoring localized fluid flow and shear stress in the complex porous scaffold by examining their variation trends at perfusion rate of 5, 8, 10 and 12 ml/hr. Then, we developed the 3D porous cellular constructs, cell-seeded chitosan scaffolds monitored during several days by DOCT. The fiber based fourier domain DOCT employed a 1300 nm superluminescent diode with a bandwidth of 52 nm and a xyz resolution of 20×20×15 μm in free space. This setup allowed us not only to assess the cell growth and ECM deposition by observing their different scattering behaviors but also to further investigate how the cell attachment and ECM production has the effect on the flow shear stress and the relationship between flow rate and shear stress in the developing tissue construct. The possibility to monitor continuously the constructs under perfusion will easily indicate the effect of flow rate or shear stress on the cell viability and cell proliferation, and then discriminate the perfusion parameters affecting the pre-tissue formation rate growth.

CFHTLenS: a Gaussian likelihood is a sufficient approximation for a cosmological analysis of third-order cosmic shear statistics

Science.gov (United States)

Simon, P.; Semboloni, E.; van Waerbeke, L.; Hoekstra, H.; Erben, T.; Fu, L.; Harnois-Déraps, J.; Heymans, C.; Hildebrandt, H.; Kilbinger, M.; Kitching, T. D.; Miller, L.; Schrabback, T.

2015-05-01

We study the correlations of the shear signal between triplets of sources in the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS) to probe cosmological parameters via the matter bispectrum. In contrast to previous studies, we adopt a non-Gaussian model of the data likelihood which is supported by our simulations of the survey. We find that for state-of-the-art surveys, similar to CFHTLenS, a Gaussian likelihood analysis is a reasonable approximation, albeit small differences in the parameter constraints are already visible. For future surveys we expect that a Gaussian model becomes inaccurate. Our algorithm for a refined non-Gaussian analysis and data compression is then of great utility especially because it is not much more elaborate if simulated data are available. Applying this algorithm to the third-order correlations of shear alone in a blind analysis, we find a good agreement with the standard cosmological model: Σ _8=σ _8(Ω _m/0.27)^{0.64}=0.79^{+0.08}_{-0.11} for a flat Λ cold dark matter cosmology with h = 0.7 ± 0.04 (68 per cent credible interval). Nevertheless our models provide only moderately good fits as indicated by χ2/dof = 2.9, including a 20 per cent rms uncertainty in the predicted signal amplitude. The models cannot explain a signal drop on scales around 15 arcmin, which may be caused by systematics. It is unclear whether the discrepancy can be fully explained by residual point spread function systematics of which we find evidence at least on scales of a few arcmin. Therefore we need a better understanding of higher order correlations of cosmic shear and their systematics to confidently apply them as cosmological probes.

Muon tomography with momentum measurements for fast detection of nuclear materials at ports of entry

Energy Technology Data Exchange (ETDEWEB)

Erlandson, A.; Anghel, V. [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada); Armitage, J. [Carleton Univ., Physics Dept., Ottawa, Ontario (Canada); and others

2015-03-15

Muon tomography uses naturally occurring high energy cosmic ray particles called muons to statistically reconstruct 3D images of targets analogously to techniques widely used in medical physics. The Cosmic Ray Inspection and Passive Tomography (CRIPT) detector is a Canadian initiative that has demonstrated that the concept of tomography can be applied to cargo using cosmic ray muons. The unique aspect of the CRIPT detector is its use of muon momentum information which decreases the scanning time required to reconstruct an image. The CRIPT detector is currently operating at Atomic Energy of Canada Limited's (AECL) Chalk River Laboratories. (author)

Muon tomography with momentum measurements for fast detection of nuclear materials at ports of entry

International Nuclear Information System (INIS)

Erlandson, A.; Anghel, V.; Armitage, J.

2015-01-01

Muon tomography uses naturally occurring high energy cosmic ray particles called muons to statistically reconstruct 3D images of targets analogously to techniques widely used in medical physics. The Cosmic Ray Inspection and Passive Tomography (CRIPT) detector is a Canadian initiative that has demonstrated that the concept of tomography can be applied to cargo using cosmic ray muons. The unique aspect of the CRIPT detector is its use of muon momentum information which decreases the scanning time required to reconstruct an image. The CRIPT detector is currently operating at Atomic Energy of Canada Limited's (AECL) Chalk River Laboratories. (author)

Muon tomography with momentum measurements for fast detection of nuclear materials at ports of entry

International Nuclear Information System (INIS)

Erlandson, A.; Anghel, V.; Armitage, J.

2014-01-01

Muon tomography uses naturally occurring high energy cosmic ray particles called muons to statistically reconstruct 3D images of targets analogously to techniques widely used in medical physics. The Cosmic Ray Inspection and Passive Tomography (CRIPT) detector is a Canadian initiative that has demonstrated that the concept of tomography can be applied to cargo using cosmic ray muons. The unique aspect of the CRIPT detector is its use of muon momentum information which decreases the scanning time required to reconstruct an image. The CRIPT detector is currently operating at Atomic Energy of Canada Limited's (AECL) Chalk River Laboratories. (author)

Muon tomography with momentum measurements for fast detection of nuclear materials at ports of entry

Energy Technology Data Exchange (ETDEWEB)

Erlandson, A.; Anghel, V. [Atomic Energy of Canada Limited, Chalk River, ON (Canada); Armitage, J. [Carleton Univ., Physics Dept., Ottawa, ON (Canada); and others

2014-07-01

Muon tomography uses naturally occurring high energy cosmic ray particles called muons to statistically reconstruct 3D images of targets analogously to techniques widely used in medical physics. The Cosmic Ray Inspection and Passive Tomography (CRIPT) detector is a Canadian initiative that has demonstrated that the concept of tomography can be applied to cargo using cosmic ray muons. The unique aspect of the CRIPT detector is its use of muon momentum information which decreases the scanning time required to reconstruct an image. The CRIPT detector is currently operating at Atomic Energy of Canada Limited's (AECL) Chalk River Laboratories. (author)

Evidence for crustal low shear-wave speed in western Saudi Arabia from multi-scale fundamental-mode Rayleigh-wave group-velocity tomography

KAUST Repository

Tang, Zheng

2018-05-15

We investigate the crustal and upper-mantle shear-velocity structure of Saudi Arabia by fundamental-mode Rayleigh-wave group-velocity tomography and shear-wave velocity inversion. The seismic dataset is compiled using ∼140 stations of the Saudi National Seismic Network (SNSN) operated by the Saudi Geological Survey (SGS). We measure Rayleigh-wave group-velocities at periods of 8–40 s from regional earthquakes. After obtaining 1-D shear-wave velocity models by inverting group-velocities at each grid node, we construct a 3-D shear-velocity model for Saudi Arabia and adjacent regions by interpolating the 1-D models. Our 3-D model indicates significant lateral variations in crustal and lithospheric thickness, as well as in the shear-wave velocity over the study region. In particular, we identify zones of reduced shear-wave speed at crustal levels beneath the Cenozoic volcanic fields in the Arabian Shield. The inferred reductions of 2–5% in shear-wave speed may be interpreted as possibly indicating the presence of partial melts. However, their precise origin we can only speculate about. Our study also reveals an upper-mantle low velocity zone (LVZ) below the Arabian Shield, supporting the model of lateral mantle flow from the Afar plume. Further geophysical experiments are needed to confirm (or refute) the hypothesis that partial melts may exist below the Cenozoic volcanism in western Saudi Arabia, and to build a comprehensive geodynamic–geological model for the evolution and present state of the lithosphere of the Arabian Plate and the Red Sea.

Evidence for crustal low shear-wave speed in western Saudi Arabia from multi-scale fundamental-mode Rayleigh-wave group-velocity tomography

KAUST Repository

Tang, Zheng; Mai, Paul Martin; Chang, Sung-Joon; Zahran, Hani

2018-01-01

We investigate the crustal and upper-mantle shear-velocity structure of Saudi Arabia by fundamental-mode Rayleigh-wave group-velocity tomography and shear-wave velocity inversion. The seismic dataset is compiled using ∼140 stations of the Saudi National Seismic Network (SNSN) operated by the Saudi Geological Survey (SGS). We measure Rayleigh-wave group-velocities at periods of 8–40 s from regional earthquakes. After obtaining 1-D shear-wave velocity models by inverting group-velocities at each grid node, we construct a 3-D shear-velocity model for Saudi Arabia and adjacent regions by interpolating the 1-D models. Our 3-D model indicates significant lateral variations in crustal and lithospheric thickness, as well as in the shear-wave velocity over the study region. In particular, we identify zones of reduced shear-wave speed at crustal levels beneath the Cenozoic volcanic fields in the Arabian Shield. The inferred reductions of 2–5% in shear-wave speed may be interpreted as possibly indicating the presence of partial melts. However, their precise origin we can only speculate about. Our study also reveals an upper-mantle low velocity zone (LVZ) below the Arabian Shield, supporting the model of lateral mantle flow from the Afar plume. Further geophysical experiments are needed to confirm (or refute) the hypothesis that partial melts may exist below the Cenozoic volcanism in western Saudi Arabia, and to build a comprehensive geodynamic–geological model for the evolution and present state of the lithosphere of the Arabian Plate and the Red Sea.

How to derotate the cosmic microwave background polarization.

Science.gov (United States)

Kamionkowski, Marc

2009-03-20

If the linear polarization of the cosmic microwave background is rotated in a frequency-independent manner as it propagates from the surface of last scatter, it may introduce a B-mode polarization. Here I show that measurement of higher-order TE, EE, EB, and TB correlations induced by this rotation can be used to reconstruct the rotation angle as a function of position on the sky. This technique can be used to distinguish primordial B modes from those induced by rotation. The effects of rotation can be distinguished geometrically from similar effects due to cosmic shear.

Analyzing the cosmic variance limit of remote dipole measurements of the cosmic microwave background using the large-scale kinetic Sunyaev Zel'dovich effect

Energy Technology Data Exchange (ETDEWEB)

Terrana, Alexandra; Johnson, Matthew C. [Department of Physics and Astronomy, York University, Toronto, Ontario, M3J 1P3 (Canada); Harris, Mary-Jean, E-mail: aterrana@perimeterinstitute.ca, E-mail: mharris8@perimeterinstitute.ca, E-mail: mjohnson@perimeterinstitute.ca [Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5 (Canada)

2017-02-01

Due to cosmic variance we cannot learn any more about large-scale inhomogeneities from the primary cosmic microwave background (CMB) alone. More information on large scales is essential for resolving large angular scale anomalies in the CMB. Here we consider cross correlating the large-scale kinetic Sunyaev Zel'dovich (kSZ) effect and probes of large-scale structure, a technique known as kSZ tomography. The statistically anisotropic component of the cross correlation encodes the CMB dipole as seen by free electrons throughout the observable Universe, providing information about long wavelength inhomogeneities. We compute the large angular scale power asymmetry, constructing the appropriate transfer functions, and estimate the cosmic variance limited signal to noise for a variety of redshift bin configurations. The signal to noise is significant over a large range of power multipoles and numbers of bins. We present a simple mode counting argument indicating that kSZ tomography can be used to estimate more modes than the primary CMB on comparable scales. A basic forecast indicates that a first detection could be made with next-generation CMB experiments and galaxy surveys. This paper motivates a more systematic investigation of how close to the cosmic variance limit it will be possible to get with future observations.

SHEAR ACCELERATION IN EXPANDING FLOWS

Energy Technology Data Exchange (ETDEWEB)

Rieger, F. M. [ZAH, Institut für Theoretische Astrophysik, Universität Heidelberg, Philosophenweg 12, D-69120 Heidelberg (Germany); Duffy, P., E-mail: frank.rieger@mpi-hd.mpg.de, E-mail: peter.duffy@ucd.ie [University College Dublin, Belfield, Dublin 4 (Ireland)

2016-12-10

Shear flows are naturally expected to occur in astrophysical environments and potential sites of continuous non-thermal Fermi-type particle acceleration. Here we investigate the efficiency of expanding relativistic outflows to facilitate the acceleration of energetic charged particles to higher energies. To this end, the gradual shear acceleration coefficient is derived based on an analytical treatment. The results are applied to the context of the relativistic jets from active galactic nuclei. The inferred acceleration timescale is investigated for a variety of conical flow profiles (i.e., power law, Gaussian, Fermi–Dirac) and compared to the relevant radiative and non-radiative loss timescales. The results exemplify that relativistic shear flows are capable of boosting cosmic-rays to extreme energies. Efficient electron acceleration, on the other hand, requires weak magnetic fields and may thus be accompanied by a delayed onset of particle energization and affect the overall jet appearance (e.g., core, ridge line, and limb-brightening).

A new method for imaging nuclear threats using cosmic ray muons

International Nuclear Information System (INIS)

Morris, C. L.; Bacon, Jeffrey; Borozdin, Konstantin; Miyadera, Haruo; Perry, John; Rose, Evan; Watson, Scott; White, Tim; Aberle, Derek; Green, J. Andrew; McDuff, George G.; Lukić, Zarija; Milner, Edward C.

2013-01-01

Muon tomography is a technique that uses cosmic ray muons to generate three dimensional images of volumes using information contained in the Coulomb scattering of the muons. Advantages of this technique are the ability of cosmic rays to penetrate significant overburden and the absence of any additional dose delivered to subjects under study above the natural cosmic ray flux. Disadvantages include the relatively long exposure times and poor position resolution and complex algorithms needed for reconstruction. Here we demonstrate a new method for obtaining improved position resolution and statistical precision for objects with spherical symmetry.

A new method for imaging nuclear threats using cosmic ray muons

Science.gov (United States)

Morris, C. L.; Bacon, Jeffrey; Borozdin, Konstantin; Miyadera, Haruo; Perry, John; Rose, Evan; Watson, Scott; White, Tim; Aberle, Derek; Green, J. Andrew; McDuff, George G.; Lukić, Zarija; Milner, Edward C.

2013-08-01

Muon tomography is a technique that uses cosmic ray muons to generate three dimensional images of volumes using information contained in the Coulomb scattering of the muons. Advantages of this technique are the ability of cosmic rays to penetrate significant overburden and the absence of any additional dose delivered to subjects under study above the natural cosmic ray flux. Disadvantages include the relatively long exposure times and poor position resolution and complex algorithms needed for reconstruction. Here we demonstrate a new method for obtaining improved position resolution and statistical precision for objects with spherical symmetry.

A new method for imaging nuclear threats using cosmic ray muons

Energy Technology Data Exchange (ETDEWEB)

Morris, C. L.; Bacon, Jeffrey; Borozdin, Konstantin; Miyadera, Haruo; Perry, John; Rose, Evan; Watson, Scott; White, Tim [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Aberle, Derek; Green, J. Andrew; McDuff, George G. [National Security Technologies, Los Alamos, NM 87544 (United States); Lukić, Zarija [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Milner, Edward C. [Southern Methodist University, Dallas, TX 75205 (United States)

2013-08-15

Muon tomography is a technique that uses cosmic ray muons to generate three dimensional images of volumes using information contained in the Coulomb scattering of the muons. Advantages of this technique are the ability of cosmic rays to penetrate significant overburden and the absence of any additional dose delivered to subjects under study above the natural cosmic ray flux. Disadvantages include the relatively long exposure times and poor position resolution and complex algorithms needed for reconstruction. Here we demonstrate a new method for obtaining improved position resolution and statistical precision for objects with spherical symmetry.

A new method for imaging nuclear threats using cosmic ray muons

Directory of Open Access Journals (Sweden)

C. L. Morris

2013-08-01

Full Text Available Muon tomography is a technique that uses cosmic ray muons to generate three dimensional images of volumes using information contained in the Coulomb scattering of the muons. Advantages of this technique are the ability of cosmic rays to penetrate significant overburden and the absence of any additional dose delivered to subjects under study above the natural cosmic ray flux. Disadvantages include the relatively long exposure times and poor position resolution and complex algorithms needed for reconstruction. Here we demonstrate a new method for obtaining improved position resolution and statistical precision for objects with spherical symmetry.

Shear wave velocity structure of the Anatolian Plate and surrounding regions using Ambient Noise Tomography

Science.gov (United States)

Delph, J. R.; Beck, S. L.; Zandt, G.; Biryol, C. B.; Ward, K. M.

2013-12-01

The Anatolian Plate consists of various lithospheric terranes amalgamated during the closure of the Tethys Ocean, and is currently extruding to the west in response to a combination of the collision of the Arabian plate in the east and the roll back of the Aegean subduction zone in the west. We used Ambient Noise Tomography (ANT) at periods structure of the Anatolian Plate. We computed a total of 13,779 unique cross-correlations using one sample-per-second vertical component broadband seismic data from 215 stations from 8 different networks over a period of 7 years to compute fundamental-mode Rayleigh wave dispersion curves following the method of Benson et al. (2007). We then inverted the dispersion data to calculate phase velocity maps for 11 periods from 8 s - 40 s throughout Anatolia and the Aegean regions (Barmin et al. 2001). Using smoothed Moho values derived from Vanacore et al. (2013) in our starting models, we inverted our dispersion curves using a linear least-squares iterative inversion scheme (Herrmann & Ammon 2004) to produce a 3-D shear-wave velocity model of the crust and uppermost mantle throughout Anatolia and the Aegean. We find a good correlation between our seismic shear wave velocities and paleostructures (suture zones) and modern deformation (basin formation and fault deformation). The most prominent crustal velocity contrasts occur across intercontinental sutures zones, resulting from the juxtaposition of the compositionally different basements of the amalgamated terranes. At shallow depths, seismic velocity contrasts correspond closely with surficial features. The Thrace, Cankiri and Tuz Golu basins, and accretionary complexes related to the closure of the Neotethys are characterized by slow shear wave velocities, while the Menderes and Kirsehir Massifs, Pontides, and Istanbul Zone are characterized by fast velocities. We find that the East Anatolia Plateau has slow shear-wave velocities, as expected due to high heat flow and active

Horizontal cosmic ray muon radiography for imaging nuclear threats

International Nuclear Information System (INIS)

Morris, Christopher L.; Bacon, Jeffrey; Borozdin, Konstantin; Fabritius, Joseph; Miyadera, Haruo; Perry, John; Sugita, Tsukasa

2014-01-01

Muon tomography is a technique that uses information contained in the Coulomb scattering of cosmic ray muons to generate three dimension images of volumes between tracking detectors. Advantages of this technique are the muons ability to penetrate significant overburden and the absence of any additional dose beyond the natural cosmic ray flux. Disadvantages include the long exposure times and limited resolution because of the low flux. Here we compare the times needed to image objects using both vertically and horizontally mounted tracking detectors and we develop a predictive model for other geometries

Horizontal cosmic ray muon radiography for imaging nuclear threats

Science.gov (United States)

Morris, Christopher L.; Bacon, Jeffrey; Borozdin, Konstantin; Fabritius, Joseph; Miyadera, Haruo; Perry, John; Sugita, Tsukasa

2014-07-01

Muon tomography is a technique that uses information contained in the Coulomb scattering of cosmic ray muons to generate three dimension images of volumes between tracking detectors. Advantages of this technique are the muons ability to penetrate significant overburden and the absence of any additional dose beyond the natural cosmic ray flux. Disadvantages include the long exposure times and limited resolution because of the low flux. Here we compare the times needed to image objects using both vertically and horizontally mounted tracking detectors and we develop a predictive model for other geometries.

Historical building monitoring by means of a cosmic ray tracking system

International Nuclear Information System (INIS)

Zenoni, Aldo

2015-01-01

Cosmic ray radiation is mostly composed, at sea level, by high energy muons, which are highly penetrating particles capable of crossing kilometers of rock. The ubiquitous and steady presence at the Earth's surface and the high penetration capability have motivated the use of cosmic ray radiation also in fields beyond particle physics, from geology, archaeology, speleology to industrial applications and homeland security. In particular, in recent years, the novel technique of muon tomography has been proposed, with the aim of performing non invasive inspection of large non accessible volumes, material atomic number Z and density discrimination, and three dimension image reconstruction of the inspected volume. In the present paper, after a short recall of the physical principles and mathematical formalism on which muon tomography is based, a number of examples of application of the novel technique in industry and homeland security issues is given. Moreover, a new application of cosmic rays detection techniques in the field of civil engineering is proposed. The aim is the monitoring of the stability of large structures, in particular the static monitoring of historical buildings, where conservation constraints are more severe and the time evolution of the deformation phenomena under study may be of the order of months or years. The new technique may be seen, in some way, as the reverse problem of muon tomography. As a significant case study, the monitoring of the wooden vaulted roof of the Palazzo della Loggia in the town of Brescia, in Italy, has been considered. The feasibility as well as the performances and limitations of a monitoring system based on cosmic ray tracking have been studied by Monte Carlo simulation and discussed in comparison with more traditional monitoring systems. (authors)

Historical building monitoring by means of a cosmic ray tracking system

Energy Technology Data Exchange (ETDEWEB)

Zenoni, Aldo [Department of Mechanical and Industrial Engineering of the University of Brescia, Via Branze 38, 25123 Brescia, (Italy); INFN Sezione di Pavia, Via Bassi 6, 27100 Pavia, (Italy)

2015-07-01

Cosmic ray radiation is mostly composed, at sea level, by high energy muons, which are highly penetrating particles capable of crossing kilometers of rock. The ubiquitous and steady presence at the Earth's surface and the high penetration capability have motivated the use of cosmic ray radiation also in fields beyond particle physics, from geology, archaeology, speleology to industrial applications and homeland security. In particular, in recent years, the novel technique of muon tomography has been proposed, with the aim of performing non invasive inspection of large non accessible volumes, material atomic number Z and density discrimination, and three dimension image reconstruction of the inspected volume. In the present paper, after a short recall of the physical principles and mathematical formalism on which muon tomography is based, a number of examples of application of the novel technique in industry and homeland security issues is given. Moreover, a new application of cosmic rays detection techniques in the field of civil engineering is proposed. The aim is the monitoring of the stability of large structures, in particular the static monitoring of historical buildings, where conservation constraints are more severe and the time evolution of the deformation phenomena under study may be of the order of months or years. The new technique may be seen, in some way, as the reverse problem of muon tomography. As a significant case study, the monitoring of the wooden vaulted roof of the Palazzo della Loggia in the town of Brescia, in Italy, has been considered. The feasibility as well as the performances and limitations of a monitoring system based on cosmic ray tracking have been studied by Monte Carlo simulation and discussed in comparison with more traditional monitoring systems. (authors)

Alignments of the galaxies in and around the Virgo cluster with the local velocity shear

International Nuclear Information System (INIS)

Lee, Jounghun; Rey, Soo Chang; Kim, Suk

2014-01-01

Observational evidence is presented for the alignment between the cosmic sheet and the principal axis of the velocity shear field at the position of the Virgo cluster. The galaxies in and around the Virgo cluster from the Extended Virgo Cluster Catalog that was recently constructed by Kim et al. are used to determine the direction of the local sheet. The peculiar velocity field reconstructed from the Sloan Digital Sky Survey Data Release 7 is analyzed to estimate the local velocity shear tensor at the Virgo center. Showing first that the minor principal axis of the local velocity shear tensor is almost parallel to the direction of the line of sight, we detect a clear signal of alignment between the positions of the Virgo satellites and the intermediate principal axis of the local velocity shear projected onto the plane of the sky. Furthermore, the dwarf satellites are found to appear more strongly aligned than their normal counterparts, which is interpreted as an indication of the following. (1) The normal satellites and the dwarf satellites fall in the Virgo cluster preferentially along the local filament and the local sheet, respectively. (2) The local filament is aligned with the minor principal axis of the local velocity shear while the local sheet is parallel to the plane spanned by the minor and intermediate principal axes. Our result is consistent with the recent numerical claim that the velocity shear is a good tracer of the cosmic web.

3D Cosmic Ray Muon Tomography from an Underground Tunnel

Science.gov (United States)

Guardincerri, Elena; Rowe, Charlotte; Schultz-Fellenz, Emily; Roy, Mousumi; George, Nicolas; Morris, Christopher; Bacon, Jeffrey; Durham, Matthew; Morley, Deborah; Plaud-Ramos, Kenie; Poulson, Daniel; Baker, Diane; Bonneville, Alain; Kouzes, Richard

2017-05-01

We present an underground cosmic ray muon tomographic experiment imaging 3D density of overburden, part of a joint study with differential gravity. Muon data were acquired at four locations within a tunnel beneath Los Alamos, New Mexico, and used in a 3D tomographic inversion to recover the spatial variation in the overlying rock-air interface, and compared with a priori knowledge of the topography. Densities obtained exhibit good agreement with preliminary results of the gravity modeling, which will be presented elsewhere, and are compatible with values reported in the literature. The modeled rock-air interface matches that obtained from LIDAR within 4 m, our resolution, over much of the model volume. This experiment demonstrates the power of cosmic ray muons to image shallow geological targets using underground detectors, whose development as borehole devices will be an important new direction of passive geophysical imaging.

Disentangling dark energy and cosmic tests of gravity from weak lensing systematics

Science.gov (United States)

Laszlo, Istvan; Bean, Rachel; Kirk, Donnacha; Bridle, Sarah

2012-06-01

We consider the impact of key astrophysical and measurement systematics on constraints on dark energy and modifications to gravity on cosmic scales. We focus on upcoming photometric ‘stage III’ and ‘stage IV’ large-scale structure surveys such as the Dark Energy Survey (DES), the Subaru Measurement of Images and Redshifts survey, the Euclid survey, the Large Synoptic Survey Telescope (LSST) and Wide Field Infra-Red Space Telescope (WFIRST). We illustrate the different redshift dependencies of gravity modifications compared to intrinsic alignments, the main astrophysical systematic. The way in which systematic uncertainties, such as galaxy bias and intrinsic alignments, are modelled can change dark energy equation-of-state parameter and modified gravity figures of merit by a factor of 4. The inclusion of cross-correlations of cosmic shear and galaxy position measurements helps reduce the loss of constraining power from the lensing shear surveys. When forecasts for Planck cosmic microwave background and stage IV surveys are combined, constraints on the dark energy equation-of-state parameter and modified gravity model are recovered, relative to those from shear data with no systematic uncertainties, provided fewer than 36 free parameters in total are used to describe the galaxy bias and intrinsic alignment models as a function of scale and redshift. While some uncertainty in the intrinsic alignment (IA) model can be tolerated, it is going to be important to be able to parametrize IAs well in order to realize the full potential of upcoming surveys. To facilitate future investigations, we also provide a fitting function for the matter power spectrum arising from the phenomenological modified gravity model we consider.

Noise reduction in muon tomography for detecting high density objects

International Nuclear Information System (INIS)

Benettoni, M; Checchia, P; Cossutta, L; Furlan, M; Gonella, F; Pegoraro, M; Garola, A Rigoni; Ronchese, P; Vanini, S; Viesti, G; Bettella, G; Bonomi, G; Donzella, A; Subieta, M; Zenoni, A; Calvagno, G; Cortelazzo, G; Zanuttigh, P; Calvini, P; Squarcia, S

2013-01-01

The muon tomography technique, based on multiple Coulomb scattering of cosmic ray muons, has been proposed as a tool to detect the presence of high density objects inside closed volumes. In this paper a new and innovative method is presented to handle the density fluctuations (noise) of reconstructed images, a well known problem of this technique. The effectiveness of our method is evaluated using experimental data obtained with a muon tomography prototype located at the Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (INFN). The results reported in this paper, obtained with real cosmic ray data, show that with appropriate image filtering and muon momentum classification, the muon tomography technique can detect high density materials, such as lead, albeit surrounded by light or medium density material, in short times. A comparison with algorithms published in literature is also presented

Historical Building Stability Monitoring by Means of a Cosmic Ray Tracking System

Energy Technology Data Exchange (ETDEWEB)

Zenoni, Aldo [Department of Mechanical and Industrial Engineering of the University of Brescia, Via Branze 38, 25123 Brescia (Italy); INFN Sezione di Pavia, Via Bassi 6, 27100 Pavia (Italy)

2015-07-01

Cosmic ray radiation is mostly composed, at sea level, by high energy muons, which are highly penetrating particles capable of crossing kilometers of rock. The ubiquitous and steady presence at the Earth's surface and the high penetration capability have motivated the use of cosmic ray radiation also in fields beyond particle physics, from geology, archaeology, speleology to industrial applications and homeland security. In particular, in recent years, the novel technique of muon tomography has been proposed, with the aim of performing non invasive inspection of large non accessible volumes, material atomic number Z and density discrimination, and three dimension image reconstruction of the inspected volume. In the present paper, after a short recall of the physical principles and mathematical formalism on which muon tomography is based, a number of examples of application of the novel technique in industry and homeland security issues is given. Moreover, a new application of cosmic rays detection techniques in the field of civil engineering is proposed. The aim is the monitoring of the stability of large structures, in particular the static monitoring of historical buildings, where conservation constraints are more severe and the time evolution of the deformation phenomena under study may be of the order of months or years. The new technique may be seen, in some way, as the reverse problem of muon tomography. As a significant case study, the monitoring of the wooden vaulted roof of the Palazzo della Loggia in the town of Brescia, in Italy, has been considered. The feasibility as well as the performances and limitations of a monitoring system based on cosmic ray tracking have been studied by Monte Carlo simulation and discussed in comparison with more traditional monitoring systems. (authors)

Historical Building Stability Monitoring by Means of a Cosmic Ray Tracking System

International Nuclear Information System (INIS)

Zenoni, Aldo

2015-01-01

Cosmic ray radiation is mostly composed, at sea level, by high energy muons, which are highly penetrating particles capable of crossing kilometers of rock. The ubiquitous and steady presence at the Earth's surface and the high penetration capability have motivated the use of cosmic ray radiation also in fields beyond particle physics, from geology, archaeology, speleology to industrial applications and homeland security. In particular, in recent years, the novel technique of muon tomography has been proposed, with the aim of performing non invasive inspection of large non accessible volumes, material atomic number Z and density discrimination, and three dimension image reconstruction of the inspected volume. In the present paper, after a short recall of the physical principles and mathematical formalism on which muon tomography is based, a number of examples of application of the novel technique in industry and homeland security issues is given. Moreover, a new application of cosmic rays detection techniques in the field of civil engineering is proposed. The aim is the monitoring of the stability of large structures, in particular the static monitoring of historical buildings, where conservation constraints are more severe and the time evolution of the deformation phenomena under study may be of the order of months or years. The new technique may be seen, in some way, as the reverse problem of muon tomography. As a significant case study, the monitoring of the wooden vaulted roof of the Palazzo della Loggia in the town of Brescia, in Italy, has been considered. The feasibility as well as the performances and limitations of a monitoring system based on cosmic ray tracking have been studied by Monte Carlo simulation and discussed in comparison with more traditional monitoring systems. (authors)

Dynamics of bubble-bubble interaction in sheared low-viscosity magma imaged by X-ray computed micro-tomography

Science.gov (United States)

Helo, C.; Flaws, A.; Hess, K.-U.; Franz, A.; Clague, D. A.; Dingwell, D. B.

2012-04-01

X-ray computed tomography of vesicles in basaltic pyroclastic glass fragments has been used to investigate the syn-eruptive shear environment and resulting bubble-bubble interaction during mild pyroclastic eruptions in a mid-ocean ridge environment. We have imaged vesicles present in two different types of pyroclastic fragments produced by mildly explosive activity on Axial Seamount, limu o Pele, that is, thin glass films often described as bubble walls, and tube scoria fragments. Rapid quenching of the glass has prevented extensive bubble relaxation preserving the syn-eruptive geometry of the bubbles in these fragments. Isolated, ellipsoid-shaped vesicles in low-vesicular limu o Pele indicate deformation in a simple shear environment. Under these shear conditions higher vesiculated parts of the erupting magma show strong bubble-bubble interactions partially leading to coalscence and formation of tubular vesicles. These tubular vesicles can reach significant lengths, exceeding the dimensions of the small glass fragments (2 mm). Their unreformed radius can be more then one order of magnitude larger than that of the isolated vesicles in the limu o Pele fragments. We can distinguish two principle modes of interaction based on the relative orientation of the bubbles. Interaction along the sidewalls of two bubbles, and tip-to-tip interaction. At interdistances of less than a few tens of micrometre, interaction of the sidewalls results in deformation of the bubbles to more irregular shapes, with depressions caused by close, small bubbles or in some cases bubbles being partially mantled around tubular bubbles. This often leads to a more close packing of bubbles. At distances of less than a few microns, the melt films between the bubbles destabilize leading to coalescence. This mechanism appears to involve a bulging of the larger bubble into the smaller, followed by melt film rapture and coalescence. The complete digestion of one bubble by the other is the slow rate

Effects of acoustic radiation force and shear waves for absorption and stiffness sensing in ultrasound modulated optical tomography.

Science.gov (United States)

Li, Rui; Elson, Daniel S; Dunsby, Chris; Eckersley, Robert; Tang, Meng-Xing

2011-04-11

Ultrasound-modulated optical tomography (UOT) combines optical contrast with ultrasound spatial resolution and has great potential for soft tissue functional imaging. One current problem with this technique is the weak optical modulation signal, primarily due to strong optical scattering in diffuse media and minimal acoustically induced modulation. The acoustic radiation force (ARF) can create large particle displacements in tissue and has been shown to be able to improve optical modulation signals. However, shear wave propagation induced by the ARF can be a significant source of nonlocal optical modulation which may reduce UOT spatial resolution and contrast. In this paper, the time evolution of shear waves was examined on tissue mimicking-phantoms exposed to 5 MHz ultrasound and 532 nm optical radiation and measured with a CCD camera. It has been demonstrated that by generating an ARF with an acoustic burst and adjusting both the timing and the exposure time of the CCD measurement, optical contrast and spatial resolution can be improved by ~110% and ~40% respectively when using the ARF rather than 5 MHz ultrasound alone. Furthermore, it has been demonstrated that this technique simultaneously detects both optical and mechanical contrast in the medium and the optical and mechanical contrast can be distinguished by adjusting the CCD exposure time. © 2011 Optical Society of America

Illuminating magma shearing processes via synchrotron imaging

Science.gov (United States)

Lavallée, Yan; Cai, Biao; Coats, Rebecca; Kendrick, Jackie E.; von Aulock, Felix W.; Wallace, Paul A.; Le Gall, Nolwenn; Godinho, Jose; Dobson, Katherine; Atwood, Robert; Holness, Marian; Lee, Peter D.

2017-04-01

Our understanding of geomaterial behaviour and processes has long fallen short due to inaccessibility into material as "something" happens. In volcanology, research strategies have increasingly sought to illuminate the subsurface of materials at all scales, from the use of muon tomography to image the inside of volcanoes to the use of seismic tomography to image magmatic bodies in the crust, and most recently, we have added synchrotron-based x-ray tomography to image the inside of material as we test it under controlled conditions. Here, we will explore some of the novel findings made on the evolution of magma during shearing. These will include observations and discussions of magma flow and failure as well as petrological reaction kinetics.

Muons tomography applied to geosciences and volcanology

Energy Technology Data Exchange (ETDEWEB)

Marteau, J., E-mail: marteau@ipnl.in2p3.fr [Institut de Physique Nucleaire de Lyon (UMR CNRS-IN2P3 5822), Universite Lyon 1, Lyon (France); Gibert, D.; Lesparre, N. [Institut de Physique du Globe de Paris (UMR CNRS 7154), Sorbonne Paris Cite, Paris (France); Nicollin, F. [Geosciences Rennes (CNRS UMR 6118), Universite Rennes 1, Bat. 15 Campus de Beaulieu, 35042 Rennes cedex (France); Noli, P. [Universita degli studi di Napoli Federico II and INFN sez. Napoli (Italy); Giacoppo, F. [Laboratory for High Energy Physics, University of Bern, SidlerStrasse 5, CH-3012 Bern (Switzerland)

2012-12-11

Imaging the inner part of large geological targets is an important issue in geosciences with various applications. Different approaches already exist (e.g. gravimetry, electrical tomography) that give access to a wide range of information but with identified limitations or drawbacks (e.g. intrinsic ambiguity of the inverse problem, time consuming deployment of sensors over large distances). Here we present an alternative and complementary tomography method based on the measurement of the cosmic muons flux attenuation through the geological structures. We detail the basics of this muon tomography with a special emphasis on the photo-active detectors.

Cosmic ray muon computed tomography of spent nuclear fuel in dry storage casks

Science.gov (United States)

Poulson, D.; Durham, J. M.; Guardincerri, E.; Morris, C. L.; Bacon, J. D.; Plaud-Ramos, K.; Morley, D.; Hecht, A. A.

2017-01-01

Radiography with cosmic ray muon scattering has proven to be a successful method of imaging nuclear material through heavy shielding. Of particular interest is monitoring dry storage casks for diversion of plutonium contained in spent reactor fuel. Using muon tracking detectors that surround a cylindrical cask, cosmic ray muon scattering can be simultaneously measured from all azimuthal angles, giving complete tomographic coverage of the cask interior. This paper describes the first application of filtered back projection algorithms, typically used in medical imaging, to cosmic ray muon scattering imaging. The specific application to monitoring spent nuclear fuel in dry storage casks is investigated via GEANT4 simulations. With a cylindrical muon tracking detector surrounding a typical spent fuel cask, simulations indicate that missing fuel bundles can be detected with a statistical significance of ∼ 18 σ in less than two days exposure and a sensitivity at 1σ to a 5% missing portion of a fuel bundle. Potential detector technologies and geometries are discussed.

A grey incidence algorithm to detect high-Z material using cosmic ray muons

Science.gov (United States)

He, W.; Xiao, S.; Shuai, M.; Chen, Y.; Lan, M.; Wei, M.; An, Q.; Lai, X.

2017-10-01

Muon scattering tomography (MST) is a method for using cosmic muons to scan cargo containers and vehicles for special nuclear materials. However, the flux of cosmic ray muons is low, in the real life application, the detection has to be done a short timescale with small numbers of muons. In this paper, we present a novel approach to detection of special nuclear material by using cosmic ray muons. We use the degree of grey incidence to distinguish typical waste fuel material, uranium, from low-Z material, medium-Z material and other high-Z materials of tungsten and lead. The result shows that using this algorithm, it is possible to detect high-Z materials with an acceptable timescale.

Design and implementation of a shearing apparatus for the experimental study of shear displacement in rocks

Science.gov (United States)

Moore, Johnathan; Crandall, Dustin; Gill, Magdalena; Brown, Sarah; Tennant, Bryan

2018-04-01

Fluid flow in the subsurface is not well understood in the context of "impermeable" geologic media. This is especially true of formations that have undergone significant stress fluctuations due to injection or withdrawal of fluids that alters the localized pressure regime. When the pressure regime is altered, these formations, which are often already fractured, move via shear to reduce the imbalance in the stress state. While this process is known to happen, the evolution of these fractures and their effects on fluid transport are still relatively unknown. Numerous simulation and several experimental studies have been performed that characterize the relationship between shearing and permeability in fractures; while many of these studies utilize measurements of fluid flow or the starting and ending geometries of the fracture to characterize shear, they do not characterize the intermediate stages during shear. We present an experimental apparatus based on slight modifications to a commonly available Hassler core holder that allows for shearing of rocks, while measuring the hydraulic and mechanical changes to geomaterials during intermediate steps. The core holder modification employs the use of semi-circular end caps and structural supports for the confining membrane that allow for free movement of the sheared material while preventing membrane collapse. By integrating this modified core holder with a computed tomography scanner, we show a new methodology for understanding the interdependent behavior between fracture structure and flow properties during intermediate steps in shearing. We include a case study of this device function which is shown here through shearing of a fractured shale core and simultaneous observation of the mechanical changes and evolution of the hydraulic properties during shearing.

Cosmic strings and cosmic structure

International Nuclear Information System (INIS)

Albrecht, A.; Brandenberger, R.; Turok, N.

1987-01-01

The paper concerns the application of the theory of cosmic strings to explain the structure of the Universe. The formation of cosmic strings in the early Universe is outlined, along with the Big Bang theory, Grand Unified theories, and the first three minutes after the Big Bang. A description is given of the shaping of the Universe by cosmic strings, including the evolution of the string. The possibility for direct observation of cosmic strings is discussed. (U.K.)

A prototype scintillating-fibre tracker for the cosmic-ray muon tomography of legacy nuclear waste containers

Energy Technology Data Exchange (ETDEWEB)

Mahon, D.F., E-mail: David.Mahon@Glasgow.ac.uk [Nuclear Physics Group, University of Glasgow, Kelvin Building, University Avenue, Glasgow, G12 8QQ Scotland (United Kingdom); Clarkson, A.; Hamilton, D.J.; Hoek, M.; Ireland, D.G. [Nuclear Physics Group, University of Glasgow, Kelvin Building, University Avenue, Glasgow, G12 8QQ Scotland (United Kingdom); Johnstone, J.R. [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale, Cumbria, CA20 1PG England (United Kingdom); Kaiser, R.; Keri, T.; Lumsden, S.; McKinnon, B.; Murray, M.; Nutbeam-Tuffs, S. [Nuclear Physics Group, University of Glasgow, Kelvin Building, University Avenue, Glasgow, G12 8QQ Scotland (United Kingdom); Shearer, C.; Staines, C. [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale, Cumbria, CA20 1PG England (United Kingdom); Yang, G. [Nuclear Physics Group, University of Glasgow, Kelvin Building, University Avenue, Glasgow, G12 8QQ Scotland (United Kingdom); Zimmerman, C. [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale, Cumbria, CA20 1PG England (United Kingdom)

2013-12-21

Cosmic-ray muons are highly penetrative charged particles observed at sea level with a flux of approximately 1 cm{sup −2} min{sup −1}. They interact with matter primarily through Coulomb scattering which can be exploited in muon tomography to image objects within industrial nuclear waste containers. A prototype scintillating-fibre detector has been developed for this application, consisting of two tracking modules above and below the volume to be assayed. Each module comprises two orthogonal planes of 2 mm fibres. The modular configuration allows the reconstruction of the initial and scattered muon trajectories which enable the container content, with respect to atomic number Z, to be determined. Fibre signals are read out by Hamamatsu H8500 MAPMTs with two fibres coupled to each pixel via dedicated pairing schemes developed to avoid space point ambiguities and retain the high spatial resolution of the fibres. A likelihood-based image reconstruction algorithm was developed and tested using a GEANT4 simulation of the prototype system. Images reconstructed from this simulation are presented in comparison with experimental results taken with test objects. These results verify the simulation and show discrimination between the low, medium and high-Z materials imaged.

A GENERAL STUDY OF THE INFLUENCE OF CATASTROPHIC PHOTOMETRIC REDSHIFT ERRORS ON COSMOLOGY WITH COSMIC SHEAR TOMOGRAPHY

International Nuclear Information System (INIS)

Hearin, Andrew P.; Zentner, Andrew R.; Ma Zhaoming; Huterer, Dragan

2010-01-01

A goal of forthcoming imaging surveys is to use weak gravitational lensing shear measurements to constrain dark energy. A challenge to this program is that redshifts to the lensed, source galaxies must be determined using photometric, rather than spectroscopic, information. We quantify the importance of uncalibrated photometric redshift outliers to the dark energy goals of forthcoming imaging surveys in a manner that does not assume any particular photometric redshift technique or template. In so doing, we provide an approximate blueprint for computing the influence of specific outlier populations on dark energy constraints. We find that outlier populations whose photo-z distributions are tightly localized about a significantly biased redshift must be controlled to a per-galaxy rate of (1-3) x 10 -3 to insure that systematic errors on dark energy parameters are rendered negligible. In the complementary limit, a subset of imaged galaxies with uncalibrated photometric redshifts distributed over a broad range must be limited to fewer than a per-galaxy error rate of F cat ∼ -4 . Additionally, we explore the relative importance of calibrating the photo-z's of a core set of relatively well-understood galaxies as compared to the need to identify potential catastrophic photo-z outliers. We discuss the degradation of the statistical constraints on dark energy parameters induced by excising source galaxies at high- and low-photometric redshifts, concluding that removing galaxies with photometric redshifts z ph ∼> 2.4 and z ph ∼< 0.3 may mitigate damaging catastrophic redshift outliers at a relatively small (∼<20%) cost in statistical error. In an Appendix, we show that forecasts for the degradation in dark energy parameter constraints due to uncertain photometric redshifts depend sensitively on the treatment of the nonlinear matter power spectrum. In particular, previous work using Peacock and Dodds may have overestimated the photo-z calibration requirements of

monitoring la Soufrière de Guadeloupe phreatic system with muon tomography

Science.gov (United States)

Jourde, Kevin; Gibert, Dominique; Marteau, Jacques; de Bremond d'Ars, Jean; Ianigro, Jean-Christophe; Gardien, Serge; Girerd, Claude

2015-04-01

Muon tomography is a novel geophysics imaging technique that measures the flux of cosmic muons crossing geological bodies. Its attenuation is directly related to their thickness and density. On la Soufrière de Guadeloupe volcano, we could extract tiny particle flux fluctuations from the tomography signal of long-term acquisitions (a few months). We prove that atmospheric fluctuations or solar activity, which are the usual candidates for cosmic particles time modulations, cannot explain these changes leaving the volcanic dome phreatic system as the only explanation. Moreover the temporal trends we extracted from the different observation axes of our instrument show a good spatial and temporal correlation with events occuring at the surface of the volcano.

High resolution 3-D shear wave velocity structure in South China from surface wave tomography

Science.gov (United States)

Ning, S.; Guo, Z.; Chen, Y. J.

2017-12-01

Using continuous data from a total of 638 seismic stations, including 484 from CEArray between 2008 and 2013 and 154 from SINOPROBE between 2014 and 2015, we perform both ambient noise and earthquake Rayleigh wave tomography across South China. Combining Rayleigh wave phase velocity between 6and 40s periods from ambient noise tomography and Rayleigh wave phase velocity between 20and 140s from teleseismic two-plane-wave tomography, we obtain phase velocity maps between 6 and140 s periods. We then invert Rayleigh wave phase velocity to construct a 3-D shear wave velocity structure of South China by Markov Chain Monte Carlo method. Similar to other inversion results, our results correspond topography well. Moreover, our results also reveal that velocity structure of the eastern South China in mantle depth is similar to eastern North China, the core of the western South China, Sichuan Block (SB),still exists thick lithosphere. However, owing to much more data employed and some data quality control techniques in this research, our results reveal more detailed structures. Along Qinling-Dabie Orogenic Belt (QDOB), North-South Gravity Lineament (NSGL) and the Sichuan-Yunnan Rhombic Block (SYRB), there are obvious high speed anomalies in depths of 10-20 km, which possibly imply ancient intrusions. Moreover, it seems that Tancheng-Lujiang Fault Zone (TLFZ) has already cut through QDOB, forming a deep fracture cutting through the crust of the whole China continent. Although SB still exists thick lithosphere, there are indications for thermal erosion. At the same time, the lithosphere of the central SYRB seems to be experiencing delamination process, obviously forming a barrier to prevent the hot Tibetan Plateau (TP) mantle material from flowing further southeast. Upwelling hot mantle material possibly triggered by this delamination process might be the cause of the Emeishan Large Igneous Province. There exists an intercontinental low velocity layer in the crust of the TP

Discriminating cosmic muons and X-rays based on rise time using a GEM detector

Science.gov (United States)

Wu, Hui-Yin; Zhao, Sheng-Ying; Wang, Xiao-Dong; Zhang, Xian-Ming; Qi, Hui-Rong; Zhang, Wei; Wu, Ke-Yan; Hu, Bi-Tao; Zhang, Yi

2016-08-01

Gas electron multiplier (GEM) detectors have been used in cosmic muon scattering tomography and neutron imaging over the last decade. In this work, a triple GEM device with an effective readout area of 10 cm × 10 cm is developed, and a method of discriminating between cosmic muons and X-rays based on rise time is tested. The energy resolution of the GEM detector is tested by 55Fe ray source to prove the GEM detector has a good performance. Analysis of the complete signal-cycles allows us to get the rise time and pulse heights. The experiment result indicates that cosmic muons and X-rays can be discriminated with an appropriate rise time threshold. Supported by National Natural Science Foundation of China (11135002, 11275235, 11405077, 11575073)

Spurious Shear in Weak Lensing with LSST

Energy Technology Data Exchange (ETDEWEB)

Chang, C.; Kahn, S.M.; Jernigan, J.G.; Peterson, J.R.; AlSayyad, Y.; Ahmad, Z.; Bankert, J.; Bard, D.; Connolly, A.; Gibson, R.R.; Gilmore, K.; Grace, E.; Hannel, M.; Hodge, M.A.; Jee, M.J.; Jones, L.; Krughoff, S.; Lorenz, S.; Marshall, P.J.; Marshall, S.; Meert, A.

2012-09-19

The complete 10-year survey from the Large Synoptic Survey Telescope (LSST) will image {approx} 20,000 square degrees of sky in six filter bands every few nights, bringing the final survey depth to r {approx} 27.5, with over 4 billion well measured galaxies. To take full advantage of this unprecedented statistical power, the systematic errors associated with weak lensing measurements need to be controlled to a level similar to the statistical errors. This work is the first attempt to quantitatively estimate the absolute level and statistical properties of the systematic errors on weak lensing shear measurements due to the most important physical effects in the LSST system via high fidelity ray-tracing simulations. We identify and isolate the different sources of algorithm-independent, additive systematic errors on shear measurements for LSST and predict their impact on the final cosmic shear measurements using conventional weak lensing analysis techniques. We find that the main source of the errors comes from an inability to adequately characterise the atmospheric point spread function (PSF) due to its high frequency spatial variation on angular scales smaller than {approx} 10{prime} in the single short exposures, which propagates into a spurious shear correlation function at the 10{sup -4}-10{sup -3} level on these scales. With the large multi-epoch dataset that will be acquired by LSST, the stochastic errors average out, bringing the final spurious shear correlation function to a level very close to the statistical errors. Our results imply that the cosmological constraints from LSST will not be severely limited by these algorithm-independent, additive systematic effects.

Measurement of a Cosmographic Distance Ratio with Galaxy and Cosmic Microwave Background Lensing.

Science.gov (United States)

Miyatake, Hironao; Madhavacheril, Mathew S; Sehgal, Neelima; Slosar, Anže; Spergel, David N; Sherwin, Blake; van Engelen, Alexander

2017-04-21

We measure the gravitational lensing shear signal around dark matter halos hosting constant mass galaxies using light sources at z∼1 (background galaxies) and at the surface of last scattering at z∼1100 (the cosmic microwave background). The galaxy shear measurement uses data from the CFHTLenS survey, and the microwave background shear measurement uses data from the Planck satellite. The ratio of shears from these cross-correlations provides a purely geometric distance measurement across the longest possible cosmological lever arm. This is because the matter distribution around the halos, including uncertainties in galaxy bias and systematic errors such as miscentering, cancels in the ratio for halos in thin redshift slices. We measure this distance ratio in three different redshift slices of the constant mass (CMASS) sample and combine them to obtain a 17% measurement of the distance ratio, r=0.390_{-0.062}^{+0.070}, at an effective redshift of z=0.53. This is consistent with the predicted ratio from the Planck best-fit cold dark matter model with a cosmological constant cosmology of r=0.419.

Determination of anisotropic velocity model by reflection tomography of compression and shear modes; Determination de modele de vitesse anisotrope par tomographie de reflexion des modes de compression et de cisaillement

Energy Technology Data Exchange (ETDEWEB)

Stopin, A.

2001-12-01

As the jump from 2D to 3D, seismic exploration lives a new revolution with the use of converted PS waves. Indeed PS converted waves are proving their potential as a tool for imaging through gas; lithology discrimination; structural confirmation; and more. Nevertheless, processing converted shear data and in particular determining accurate P and S velocity models for depth imaging of these data is still a challenging problem, especially when the subsurface is anisotropic. To solve this velocity model determination problem we propose to use reflection travel time tomography. In a first step, we derive a new approximation of the exact phase velocity equation of the SV wave in anisotropic (TI) media. This new approximation is valid for non-weak anisotropy and is mathematically simpler to handle than the exact equation. Then, starting from an isotropic reflection tomography tool developed at Lt-'P, we extend the isotropic bending ray tracing method to the anisotropic case and we implement the quantities necessary for the determination of the anisotropy parameters from the travel time data. Using synthetic data we then study the influence of the different anisotropy parameters on the travel times. From this analysis we propose a methodology to determine a complete anisotropic subsurface model (P and S layer velocities, interface geometries, anisotropy parameters). Finally, on a real data set from the Gulf of Mexico we demonstrate that this new anisotropic reflection tomography tool allows us to obtain a reliable subsurface model yielding kinematically correct and mutually coherent PP and PS images in depth; such a result could not be obtained with an isotropic velocity model. Similar results are obtained on a North Sea data set. (author)

Determination of anisotropic velocity model by reflection tomography of compression and shear modes; Determination de modele de vitesse anisotrope par tomographie de reflexion des modes de compression et de cisaillement

Energy Technology Data Exchange (ETDEWEB)

Stopin, A

2001-12-01

As the jump from 2D to 3D, seismic exploration lives a new revolution with the use of converted PS waves. Indeed PS converted waves are proving their potential as a tool for imaging through gas; lithology discrimination; structural confirmation; and more. Nevertheless, processing converted shear data and in particular determining accurate P and S velocity models for depth imaging of these data is still a challenging problem, especially when the subsurface is anisotropic. To solve this velocity model determination problem we propose to use reflection travel time tomography. In a first step, we derive a new approximation of the exact phase velocity equation of the SV wave in anisotropic (TI) media. This new approximation is valid for non-weak anisotropy and is mathematically simpler to handle than the exact equation. Then, starting from an isotropic reflection tomography tool developed at Lt-'P, we extend the isotropic bending ray tracing method to the anisotropic case and we implement the quantities necessary for the determination of the anisotropy parameters from the travel time data. Using synthetic data we then study the influence of the different anisotropy parameters on the travel times. From this analysis we propose a methodology to determine a complete anisotropic subsurface model (P and S layer velocities, interface geometries, anisotropy parameters). Finally, on a real data set from the Gulf of Mexico we demonstrate that this new anisotropic reflection tomography tool allows us to obtain a reliable subsurface model yielding kinematically correct and mutually coherent PP and PS images in depth; such a result could not be obtained with an isotropic velocity model. Similar results are obtained on a North Sea data set. (author)

imaging volcanos with gravity and muon tomography measurements

Science.gov (United States)

Jourde, Kevin; Gibert, Dominique; Marteau, Jacques; Deroussi, Sébastien; Dufour, Fabrice; de Bremond d'Ars, Jean; Ianigro, Jean-Christophe; Gardien, Serge; Girerd, Claude

2015-04-01

Both muon tomography and gravimetry are geohysical methods that provide information on the density structure of the Earth's subsurface. Muon tomography measures the natural flux of cosmic muons and its attenuation produced by the screening effect of the rock mass to image. Gravimetry generally consists in measurements of the vertical component of the local gravity field. Both methods are linearly linked to density, but their spatial sensitivity is very different. Muon tomography essentially works like medical X-ray scan and integrates density information along elongated narrow conical volumes while gravimetry measurements are linked to density by a 3-dimensional integral encompassing the whole studied domain. We show that gravity data are almost useless to constrain the density structure in regions sampled by more than two muon tomography acquisitions. Interestingly the resolution in deeper regions not sampled by muon tomography is significantly improved by joining the two techniques. Examples taken from field experiments performed on La Soufrière of Guadeloupe volcano are discussed.

Imaging of high-Z material for nuclear contraband detection with a minimal prototype of a muon tomography station based on GEM detectors

Energy Technology Data Exchange (ETDEWEB)

Gnanvo, Kondo, E-mail: kgnanvo@fit.edu [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States); Grasso, Leonard V.; Hohlmann, Marcus; Locke, Judson B.; Quintero, Amilkar [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States); Mitra, Debasis [Department of Computer Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States)

2011-10-01

Muon Tomography based on the measurement of multiple scattering of atmospheric cosmic ray muons in matter is a promising technique for detecting heavily shielded high-Z radioactive materials (U, Pu) in cargo or vehicles. The technique uses the deflection of cosmic ray muons in matter to perform tomographic imaging of high-Z material inside a probed volume. A Muon Tomography Station (MTS) requires position-sensitive detectors with high spatial resolution for optimal tracking of incoming and outgoing cosmic ray muons. Micro Pattern Gaseous Detector (MPGD) technologies such as Gas Electron Multiplier (GEM) detectors are excellent candidates for this application. We have built and operated a minimal MTS prototype based on 30 cmx30 cm GEM detectors for probing targets with various Z values inside the MTS volume. We report the first successful detection and imaging of medium-Z and high-Z targets of small volumes ({approx}0.03 L) using GEM-based Muon Tomography.

Imaging of high-Z material for nuclear contraband detection with a minimal prototype of a muon tomography station based on GEM detectors

International Nuclear Information System (INIS)

Gnanvo, Kondo; Grasso, Leonard V.; Hohlmann, Marcus; Locke, Judson B.; Quintero, Amilkar; Mitra, Debasis

2011-01-01

Muon Tomography based on the measurement of multiple scattering of atmospheric cosmic ray muons in matter is a promising technique for detecting heavily shielded high-Z radioactive materials (U, Pu) in cargo or vehicles. The technique uses the deflection of cosmic ray muons in matter to perform tomographic imaging of high-Z material inside a probed volume. A Muon Tomography Station (MTS) requires position-sensitive detectors with high spatial resolution for optimal tracking of incoming and outgoing cosmic ray muons. Micro Pattern Gaseous Detector (MPGD) technologies such as Gas Electron Multiplier (GEM) detectors are excellent candidates for this application. We have built and operated a minimal MTS prototype based on 30 cmx30 cm GEM detectors for probing targets with various Z values inside the MTS volume. We report the first successful detection and imaging of medium-Z and high-Z targets of small volumes (∼0.03 L) using GEM-based Muon Tomography.

Cosmic radiation

Energy Technology Data Exchange (ETDEWEB)

Capdevielle, J N

1984-01-01

First, the different instruments and techniques of cosmic particle detection are presented. Then the passage of the cosmic particles through the atmosphere is studied: electrons, photons, muons. The collective behavior of the different categories is also studied, the electromagnetic cascade is distinguished from the hadron cascade. Through the principal physical properties of the radiation and the medium, the ''mean'' aspects of the radiation are then successively dealt with out of the atmosphere, at different altitudes until the sea level, then at great depths. A chapter is devoted to cosmic radiation of more than 10,000 GeV, studied separately. Then solar radiation in universe is studied through their propagation in solar system and their origin. At last, the cosmic radiation effects are studied in environment (cosmic biophysics) and some applications of cosmic radiation are presented.

Cosmic Education: Formation of a Planetary and Cosmic Personality

Directory of Open Access Journals (Sweden)

Bazaluk Oleg

2012-04-01

Full Text Available The major stages of development of cosmic pedagogy have been researched. Based on the achievements of the modern neurosciences as well as of psychology, cosmology, and philosophy, the authors provide their reasoning for the cosmic education and its outlooks for the educational systems of the world. Through the studies of how important human mind is for the Earth and the cosmos and by researching the evolution of human mind within the structure of the Universe, the authors create a more advanced scientific and philosophic basis for the cosmic education where the subject is a comprehensive process of formation and directed progress of both an individual mind and a conglomerate of minds called the "psychospace". The cosmic education researches the permanent progress of the intelligent matter of the Earth. The purpose of the cosmic education has been determined as formation of a planetary and cosmic personality. According to the authors, a planetary and cosmic personality is a harmony of mind, soul, and body, and such harmony is directed to use the internal creative potential of mind to the benefit of the intelligent matter of the entire Earth and the cosmos. The properties of such a planetary and cosmic personality are being improved continuously; they are a sample (the ideal of the cosmic pedagogy and the image of a human being of the future. Through the usage of the entire potential and art of upbringing and educating, the cosmic pedagogy is called to embody the major properties of the image of a human being of the future in the new generations of minds and to form a planetary and cosmic personality capable of self-actualization to the benefit of the permanent progress of the intelligent matter.

Simulating the physical properties of dark matter and gas inside the cosmic web

Science.gov (United States)

Dolag, K.; Meneghetti, M.; Moscardini, L.; Rasia, E.; Bonaldi, A.

2006-08-01

Using the results of a high-resolution, cosmological hydrodynamical re-simulation of a supercluster-like region, we investigate the physical properties of the gas located along the filaments and bridges which constitute the so-called cosmic web. First, we analyse the main characteristics of the density, temperature and velocity fields, which have quite different distributions, reflecting the complex dynamics of the structure-formation process. Then we quantify the signals which originate from the matter in the filaments by considering different observables. Inside the cosmic web, we find that the halo density is about 10-14 times larger than cosmic mean; the bremsstrahlung X-ray surface brightness reaches at most 10-16 erg s-1 cm-2 arcmin-2 the Compton-y parameter due to the thermal Sunyaev-Zel'dovich effect is about 10-6 the reduced shear produced by the weak lensing effect is ~0.01-0.02. These results confirm the difficulty of an observational detection of the cosmic web. Finally, we find that projection effects of the filamentary network can affect the estimates of the properties of single clusters, increasing their X-ray luminosity by less than 10 per cent and their central Compton-y parameter by up to 30 per cent.

Measurement Over Large Solid Angle of Low Energy Cosmic Ray Muon Flux

Science.gov (United States)

Schreiner, H. F., III; Schwitters, R. F.

2015-12-01

Recent advancements in portable muon detectors have made cosmic ray imaging practical for many diverse applications. Working muon attenuation detectors have been built at the University of Texas and are already successfully being used to image tunnels, structures, and Mayan pyramids. Most previous studies have focused on energy measurements of the cosmic ray spectrum from of 1 GeV or higher. We have performed an accurate measurement of the ultra-low energy (muon spectrum down to the acceptance level of our detector, around one hundred MeV. Measurements include angular dependence, with acceptance approaching horizontal. Measurements were made underwater using a custom enclosure in Lake Travis, Austin, TX. This measurement will allow more accurate predictions and simulations of attenuation for small (muon tomography.

Applications of Cosmic Ray Muon Radiography

Science.gov (United States)

Guardincerri, E.; Durham, J. M.; Morris, C. L.; Rowe, C. A.; Poulson, D. C.; Bacon, J. D.; Plaud-Ramos, K.; Morley, D. J.

2015-12-01

The Dome of Santa Maria del Fiore, Florence Cathedral, was built between 1420 and 1436 by architect Filippo Brunelleschi and it is now cracking under its own weight. Engineering efforts are underway to model the dome's structure and reinforce it against further deterioration. According to some scholars, Brunelleschi might have built reinforcement structures into the dome itself; however, the only confirmed known subsurface reinforcement is a chain of iron and stone around the dome's base. Tomography with cosmic ray muons is a non-destructive imaging method that can be used to image the interior of the wall and therefore ascertain the layout and status of any iron substructure in the dome. We will show the results from a muon tomography measurement of iron hidden in a mockup of the dome's wall performed at Los Alamos National Lab in 2015. The sensitivity of this technique, and the status of this project will be also discussed. At last, we will show results on muon attenuation radiography of larger shallow targets.

An encoding readout method used for Multi-gap Resistive Plate Chambers (MRPCs) for muon tomography

Science.gov (United States)

Yue, X.; Zeng, M.; Wang, Y.; Wang, X.; Zeng, Z.; Zhao, Z.; Cheng, J.

2014-09-01

A muon tomography facility has been built in Tsinghua University. Because of the low flux of cosmic muon, an encoding readout method, based on the fine-fine configuration, was implemented for the 2880 channels induced signals from the Multi-gap Resistive Plate Chamber (MRPC) detectors. With the encoding method, the number of the readout electronics was dramatically reduced and thus the complexity and the cost of the facility was reduced, too. In this paper, the details of the encoding method, and the overall readout system setup in the muon tomography facility are described. With the commissioning of the facility, the readout method works well. The spatial resolution of all MRPC detectors are measured with cosmic muon and the preliminary imaging result are also given.

An encoding readout method used for Multi-gap Resistive Plate Chambers (MRPCs) for muon tomography

International Nuclear Information System (INIS)

Yue, X; Zeng, M; Wang, Y; Wang, X; Zeng, Z; Zhao, Z; Cheng, J

2014-01-01

A muon tomography facility has been built in Tsinghua University. Because of the low flux of cosmic muon, an encoding readout method, based on the fine-fine configuration, was implemented for the 2880 channels induced signals from the Multi-gap Resistive Plate Chamber (MRPC) detectors. With the encoding method, the number of the readout electronics was dramatically reduced and thus the complexity and the cost of the facility was reduced, too. In this paper, the details of the encoding method, and the overall readout system setup in the muon tomography facility are described. With the commissioning of the facility, the readout method works well. The spatial resolution of all MRPC detectors are measured with cosmic muon and the preliminary imaging result are also given

KiDS-450: tomographic cross-correlation of galaxy shear with Planck lensing

Science.gov (United States)

Harnois-Déraps, Joachim; Tröster, Tilman; Chisari, Nora Elisa; Heymans, Catherine; van Waerbeke, Ludovic; Asgari, Marika; Bilicki, Maciej; Choi, Ami; Erben, Thomas; Hildebrandt, Hendrik; Hoekstra, Henk; Joudaki, Shahab; Kuijken, Konrad; Merten, Julian; Miller, Lance; Robertson, Naomi; Schneider, Peter; Viola, Massimo

2017-10-01

We present the tomographic cross-correlation between galaxy lensing measured in the Kilo Degree Survey (KiDS-450) with overlapping lensing measurements of the cosmic microwave background (CMB), as detected by Planck 2015. We compare our joint probe measurement to the theoretical expectation for a flat Λ cold dark matter cosmology, assuming the best-fitting cosmological parameters from the KiDS-450 cosmic shear and Planck CMB analyses. We find that our results are consistent within 1σ with the KiDS-450 cosmology, with an amplitude re-scaling parameter AKiDS = 0.86 ± 0.19. Adopting a Planck cosmology, we find our results are consistent within 2σ, with APlanck = 0.68 ± 0.15. We show that the agreement is improved in both cases when the contamination to the signal by intrinsic galaxy alignments is accounted for, increasing A by ∼0.1. This is the first tomographic analysis of the galaxy lensing - CMB lensing cross-correlation signal, and is based on five photometric redshift bins. We use this measurement as an independent validation of the multiplicative shear calibration and of the calibrated source redshift distribution at high redshifts. We find that constraints on these two quantities are strongly correlated when obtained from this technique, which should therefore not be considered as a stand-alone competitive calibration tool.

Direct estimation of human trabecular bone stiffness using cone beam computed tomography.

Science.gov (United States)

Klintström, Eva; Klintström, Benjamin; Pahr, Dieter; Brismar, Torkel B; Smedby, Örjan; Moreno, Rodrigo

2018-04-10

The aim of this study was to evaluate the possibility of estimating the biomechanical properties of trabecular bone through finite element simulations by using dental cone beam computed tomography data. Fourteen human radius specimens were scanned in 3 cone beam computed tomography devices: 3-D Accuitomo 80 (J. Morita MFG., Kyoto, Japan), NewTom 5 G (QR Verona, Verona, Italy), and Verity (Planmed, Helsinki, Finland). The imaging data were segmented by using 2 different methods. Stiffness (Young modulus), shear moduli, and the size and shape of the stiffness tensor were studied. Corresponding evaluations by using micro-CT were regarded as the reference standard. The 3-D Accuitomo 80 (J. Morita MFG., Kyoto, Japan) showed good performance in estimating stiffness and shear moduli but was sensitive to the choice of segmentation method. NewTom 5 G (QR Verona, Verona, Italy) and Verity (Planmed, Helsinki, Finland) yielded good correlations, but they were not as strong as Accuitomo 80 (J. Morita MFG., Kyoto, Japan). The cone beam computed tomography devices overestimated both stiffness and shear compared with the micro-CT estimations. Finite element-based calculations of biomechanics from cone beam computed tomography data are feasible, with strong correlations for the Accuitomo 80 scanner (J. Morita MFG., Kyoto, Japan) combined with an appropriate segmentation method. Such measurements might be useful for predicting implant survival by in vivo estimations of bone properties. Copyright © 2018 Elsevier Inc. All rights reserved.

[Cosmic Microwave Background (CMB) Anisotropies

Science.gov (United States)

Silk, Joseph

1998-01-01

One of the main areas of research is the theory of cosmic microwave background (CMB) anisotropies and analysis of CMB data. Using the four year COBE data we were able to improve existing constraints on global shear and vorticity. We found that, in the flat case (which allows for greatest anisotropy), (omega/H)0 less than 10(exp -7), where omega is the vorticity and H is the Hubble constant. This is two orders of magnitude lower than the tightest, previous constraint. We have defined a new set of statistics which quantify the amount of non-Gaussianity in small field cosmic microwave background maps. By looking at the distribution of power around rings in Fourier space, and at the correlations between adjacent rings, one can identify non-Gaussian features which are masked by large scale Gaussian fluctuations. This may be particularly useful for identifying unresolved localized sources and line-like discontinuities. Levin and collaborators devised a method to determine the global geometry of the universe through observations of patterns in the hot and cold spots of the CMB. We have derived properties of the peaks (maxima) of the CMB anisotropies expected in flat and open CDM models. We represent results for angular resolutions ranging from 5 arcmin to 20 arcmin (antenna FWHM), scales that are relevant for the MAP and COBRA/SAMBA space missions and the ground-based interferometer. Results related to galaxy formation and evolution are also discussed.

Characterising encapsulated nuclear waste using cosmic-ray muon tomography

International Nuclear Information System (INIS)

Clarkson, A.; Hamilton, D.J.; Hoek, M.; Ireland, D.G.; Kaiser, R.; Keri, T.; Lumsden, S.; Mahon, D.F.; McKinnon, B.; Murray, M.; Nutbeam-Tuffs, S.; Yang, G.; Johnstone, J.R.; Shearer, C.; Zimmerman, C.

2015-01-01

Tomographic imaging techniques using the Coulomb scattering of cosmic-ray muons have been shown previously to successfully identify and characterise low- and high-Z materials within an air matrix using a prototype scintillating-fibre tracker system. Those studies were performed as the first in a series to assess the feasibility of this technology and image reconstruction techniques in characterising the potential high-Z contents of legacy nuclear waste containers for the U.K. Nuclear Industry. The present work continues the feasibility study and presents the first images reconstructed from experimental data collected using this small-scale prototype system of low- and high-Z materials encapsulated within a concrete-filled stainless-steel container. Clear discrimination is observed between the thick steel casing, the concrete matrix and the sample materials assayed. These reconstructed objects are presented and discussed in detail alongside the implications for future industrial scenarios

Characterising encapsulated nuclear waste using cosmic-ray muon tomography

Science.gov (United States)

Clarkson, A.; Hamilton, D. J.; Hoek, M.; Ireland, D. G.; Johnstone, J. R.; Kaiser, R.; Keri, T.; Lumsden, S.; Mahon, D. F.; McKinnon, B.; Murray, M.; Nutbeam-Tuffs, S.; Shearer, C.; Yang, G.; Zimmerman, C.

2015-03-01

Tomographic imaging techniques using the Coulomb scattering of cosmic-ray muons have been shown previously to successfully identify and characterise low- and high-Z materials within an air matrix using a prototype scintillating-fibre tracker system. Those studies were performed as the first in a series to assess the feasibility of this technology and image reconstruction techniques in characterising the potential high-Z contents of legacy nuclear waste containers for the U.K. Nuclear Industry. The present work continues the feasibility study and presents the first images reconstructed from experimental data collected using this small-scale prototype system of low- and high-Z materials encapsulated within a concrete-filled stainless-steel container. Clear discrimination is observed between the thick steel casing, the concrete matrix and the sample materials assayed. These reconstructed objects are presented and discussed in detail alongside the implications for future industrial scenarios.

Measuring momentum for charged particle tomography

Science.gov (United States)

Morris, Christopher; Fraser, Andrew Mcleod; Schultz, Larry Joe; Borozdin, Konstantin N.; Klimenko, Alexei Vasilievich; Sossong, Michael James; Blanpied, Gary

2010-11-23

Methods, apparatus and systems for detecting charged particles and obtaining tomography of a volume by measuring charged particles including measuring the momentum of a charged particle passing through a charged particle detector. Sets of position sensitive detectors measure scattering of the charged particle. The position sensitive detectors having sufficient mass to cause the charged particle passing through the position sensitive detectors to scatter in the position sensitive detectors. A controller can be adapted and arranged to receive scattering measurements of the charged particle from the charged particle detector, determine at least one trajectory of the charged particle from the measured scattering; and determine at least one momentum measurement of the charged particle from the at least one trajectory. The charged particle can be a cosmic ray-produced charged particle, such as a cosmic ray-produced muon. The position sensitive detectors can be drift cells, such as gas-filled drift tubes.

Weak lensing Study in VOICE Survey I: Shear Measurement

Science.gov (United States)

Fu, Liping; Liu, Dezi; Radovich, Mario; Liu, Xiangkun; Pan, Chuzhong; Fan, Zuhui; Covone, Giovanni; Vaccari, Mattia; Amaro, Valeria; Brescia, Massimo; Capaccioli, Massimo; De Cicco, Demetra; Grado, Aniello; Limatola, Luca; Miller, Lance; Napolitano, Nicola R.; Paolillo, Maurizio; Pignata, Giuliano

2018-06-01

The VST Optical Imaging of the CDFS and ES1 Fields (VOICE) Survey is a Guaranteed Time program carried out with the ESO/VST telescope to provide deep optical imaging over two 4 deg2 patches of the sky centred on the CDFS and ES1 pointings. We present the cosmic shear measurement over the 4 deg2 covering the CDFS region in the r-band using LensFit. Each of the four tiles of 1 deg2 has more than one hundred exposures, of which more than 50 exposures passed a series of image quality selection criteria for weak lensing study. The 5σ limiting magnitude in r- band is 26.1 for point sources, which is ≳1 mag deeper than other weak lensing survey in the literature (e.g. the Kilo Degree Survey, KiDS, at VST). The photometric redshifts are estimated using the VOICE u, g, r, i together with near-infrared VIDEO data Y, J, H, Ks. The mean redshift of the shear catalogue is 0.87, considering the shear weight. The effective galaxy number density is 16.35 gal/arcmin2, which is nearly twice the one of KiDS. The performance of LensFit on such a deep dataset was calibrated using VOICE-like mock image simulations. Furthermore, we have analyzed the reliability of the shear catalogue by calculating the star-galaxy cross-correlations, the tomographic shear correlations of two redshift bins and the contaminations of the blended galaxies. As a further sanity check, we have constrained cosmological parameters by exploring the parameter space with Population Monte Carlo sampling. For a flat ΛCDM model we have obtained Σ _8 = σ _8(Ω _m/0.3)^{0.5} = 0.68^{+0.11}_{-0.15}.

The Formation of Laurentia: Evidence from Shear Wave Splitting and Seismic Tomography

Science.gov (United States)

Liddell, M. V.; Bastow, I. D.; Rawlinson, N.; Darbyshire, F. A.; Gilligan, A.

2017-12-01

The northern Hudson Bay region of Canada comprises several Archean cratonic nuclei, assembled by Paleoproterozoic orogenies including the 1.8 Ga Trans-Hudson Orogen (THO) and Rinkian-Nagssugtoqidian Orogen (NO). Questions remain about how similar in scale and nature these orogens were compared to modern orogens like the Himalayas. Also in question is whether the thick Laurentian cratonic root below Hudson Bay is stratified, with a seismically-fast Archean core underlain by a lower, younger, thermal layer. We investigate these problems via shear-wave splitting and teleseismic tomography using up to 25 years of data from 65 broadband seismic stations across northern Hudson Bay. The results of the complementary studies comprise the most comprehensive study to date of mantle seismic velocity and anisotropy in northern Laurentia. Splitting parameter patterns are used to interpret multiple layers, lithospheric boundaries, dipping anisotropy, and deformation zone limits for the THO and NO. Source-side waveguide effects from Japan and the Aleutian trench are observed despite the tomographic data being exclusively relative arrival time. Mitigating steps to ensure data quality are explained and enforced. In the Hudson Strait, anisotropic fast directions (φ) generally parallel the THO, which appears in tomographic images as a strong low velocity feature relative to the neighbouring Archean cratons. Several islands in northern Hudson Bay show short length-scale changes in φ coincident with strong velocity contrasts. These are interpreted as distinct lithospheric blocks with unique deformational histories, and point to a complex, rather than simple 2-plate, collisional history for the THO. Strong evidence is presented for multiple anisotropic layers beneath Archean zones, consistent with the episodic development model of cratonic keels (e.g., Yuan & Romanowicz 2010). We show via both tomographic inversion models and SKS splitting patterns that southern Baffin Island was

Cosmic void clumps

Science.gov (United States)

Lares, M.; Luparello, H. E.; Garcia Lambas, D.; Ruiz, A. N.; Ceccarelli, L.; Paz, D.

2017-10-01

Cosmic voids are of great interest given their relation to the large scale distribution of mass and the way they trace cosmic flows shaping the cosmic web. Here we show that the distribution of voids has, in consonance with the distribution of mass, a characteristic scale at which void pairs are preferentially located. We identify clumps of voids with similar environments and use them to define second order underdensities. Also, we characterize its properties and analyze its impact on the cosmic microwave background.

Development of a cosmic rack for characterization of RPCs

International Nuclear Information System (INIS)

Sehgal, S.T.; Pant, L.M.

2011-01-01

A newly designed cosmic rack has been commissioned this year in the RPC Lab., in NPD-BARC. The rack consists of nine shelves each providing a clear area of 160 cm x 225 cm. Each of the shelf is separated by a distance of 30 cm, providing sufficient distance for fast electronics to respond and also providing an easy access for loading and removing the RPCs. The total height of the cosmic rack is 2.8 metres. A typical fully integrated RPCs covers an approximate area of 2 m 2 and weighs about 60-70 kg. The rack has been basically designed, keeping in mind the varied requirements as regards to the RPCs based current and futuristic programmes which are listed as follows: 1. Testing of large area trapezoidal bakelite gas-gaps and RPCs for the CMS experiment, keeping in mind the production rate of five RPCs per month. 2. The proposed muon tomography programme with 1m x 1m glass RPCs and 3. Characterization of glass RPCs (1m x 2m) for the INO experiment in near future

Cosmic rays

International Nuclear Information System (INIS)

Tkachev, I.I.

2014-01-01

In this talk I will review results of cosmic ray observations at the highest energies. This year the new results on energy spectra, composition and the study of arrival directions of cosmic ray primaries came from the Telescope Array collaboration. I present these results in comparison with measurements done by other recent experiments and discuss their implications for the search of cosmic ray sources. Some related results in gamma-ray astronomy and selected recent advances in theory are also covered. (author)

Cosmological constraints from the CFHTLenS shear measurements using a new, accurate, and flexible way of predicting non-linear mass clustering

Science.gov (United States)

Angulo, Raul E.; Hilbert, Stefan

2015-03-01

We explore the cosmological constraints from cosmic shear using a new way of modelling the non-linear matter correlation functions. The new formalism extends the method of Angulo & White, which manipulates outputs of N-body simulations to represent the 3D non-linear mass distribution in different cosmological scenarios. We show that predictions from our approach for shear two-point correlations at 1-300 arcmin separations are accurate at the ˜10 per cent level, even for extreme changes in cosmology. For moderate changes, with target cosmologies similar to that preferred by analyses of recent Planck data, the accuracy is close to ˜5 per cent. We combine this approach with a Monte Carlo Markov chain sampler to explore constraints on a Λ cold dark matter model from the shear correlation functions measured in the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS). We obtain constraints on the parameter combination σ8(Ωm/0.27)0.6 = 0.801 ± 0.028. Combined with results from cosmic microwave background data, we obtain marginalized constraints on σ8 = 0.81 ± 0.01 and Ωm = 0.29 ± 0.01. These results are statistically compatible with previous analyses, which supports the validity of our approach. We discuss the advantages of our method and the potential it offers, including a path to model in detail (i) the effects of baryons, (ii) high-order shear correlation functions, and (iii) galaxy-galaxy lensing, among others, in future high-precision cosmological analyses.

High speed all optical shear wave imaging optical coherence elastography (Conference Presentation)

Science.gov (United States)

Song, Shaozhen; Hsieh, Bao-Yu; Wei, Wei; Shen, Tueng; O'Donnell, Matthew; Wang, Ruikang K.

2016-03-01

Optical Coherence Elastography (OCE) is a non-invasive testing modality that maps the mechanical property of soft tissues with high sensitivity and spatial resolution using phase-sensitive optical coherence tomography (PhS-OCT). Shear wave OCE (SW-OCE) is a leading technique that relies on the speed of propagating shear waves to provide a quantitative elastography. Previous shear wave imaging OCT techniques are based on repeated M-B scans, which have several drawbacks such as long acquisition time and repeated wave stimulations. Recent developments of Fourier domain mode-locked high-speed swept-source OCT system has enabled enough speed to perform KHz B-scan rate OCT imaging. Here we propose ultra-high speed, single shot shear wave imaging to capture single-shot transient shear wave propagation to perform SW-OCE. The frame rate of shear wave imaging is 16 kHz, at A-line rate of ~1.62 MHz, which allows the detection of high-frequency shear wave of up to 8 kHz. The shear wave is generated photothermal-acoustically, by ultra-violet pulsed laser, which requires no contact to OCE subjects, while launching high frequency shear waves that carries rich localized elasticity information. The image acquisition and processing can be performed at video-rate, which enables real-time 3D elastography. SW-OCE measurements are demonstrated on tissue-mimicking phantoms and porcine ocular tissue. This approach opens up the feasibility to perform real-time 3D SW-OCE in clinical applications, to obtain high-resolution localized quantitative measurement of tissue biomechanical property.

Image characterization metrics for muon tomography

Science.gov (United States)

Luo, Weidong; Lehovich, Andre; Anashkin, Edward; Bai, Chuanyong; Kindem, Joel; Sossong, Michael; Steiger, Matt

2014-05-01

Muon tomography uses naturally occurring cosmic rays to detect nuclear threats in containers. Currently there are no systematic image characterization metrics for muon tomography. We propose a set of image characterization methods to quantify the imaging performance of muon tomography. These methods include tests of spatial resolution, uniformity, contrast, signal to noise ratio (SNR) and vertical smearing. Simulated phantom data and analysis methods were developed to evaluate metric applicability. Spatial resolution was determined as the FWHM of the point spread functions in X, Y and Z axis for 2.5cm tungsten cubes. Uniformity was measured by drawing a volume of interest (VOI) within a large water phantom and defined as the standard deviation of voxel values divided by the mean voxel value. Contrast was defined as the peak signals of a set of tungsten cubes divided by the mean voxel value of the water background. SNR was defined as the peak signals of cubes divided by the standard deviation (noise) of the water background. Vertical smearing, i.e. vertical thickness blurring along the zenith axis for a set of 2 cm thick tungsten plates, was defined as the FWHM of vertical spread function for the plate. These image metrics provided a useful tool to quantify the basic imaging properties for muon tomography.

Review of possible applications of cosmic muon tomography

International Nuclear Information System (INIS)

Checchia, P.

2016-01-01

Muon radiographic methods can be used to explore inaccessible volumes profiting of the property of muons to penetrate thick materials. An extension of the muon radiographic methods, the muon scattering tomography, was proposed for the first time in 2003 and it is based on the measurement of the multiple Coulomb scattering of muons crossing the volume under investigation. In this talk, the principles of tomographic image reconstruction are first outlined and then the experimental setup and the most adequate detectors are described. A review of the possible applications of this technique is reported, with specific reference to security in transports and monitoring of industrial processes. The technique can also be used to provide precise measurements of the properties of various materials. The experimental challenge related to this activity is discussed.

Review of possible applications of cosmic muon tomography

Science.gov (United States)

Checchia, P.

2016-12-01

Muon radiographic methods can be used to explore inaccessible volumes profiting of the property of muons to penetrate thick materials. An extension of the muon radiographic methods, the muon scattering tomography, was proposed for the first time in 2003 and it is based on the measurement of the multiple Coulomb scattering of muons crossing the volume under investigation. In this talk, the principles of tomographic image reconstruction are first outlined and then the experimental setup and the most adequate detectors are described. A review of the possible applications of this technique is reported, with specific reference to security in transports and monitoring of industrial processes. The technique can also be used to provide precise measurements of the properties of various materials. The experimental challenge related to this activity is discussed.

Shear Elasticity and Shear Viscosity Imaging in Soft Tissue

Science.gov (United States)

Yang, Yiqun

In this thesis, a new approach is introduced that provides estimates of shear elasticity and shear viscosity using time-domain measurements of shear waves in viscoelastic media. Simulations of shear wave particle displacements induced by an acoustic radiation force are accelerated significantly by a GPU. The acoustic radiation force is first calculated using the fast near field method (FNM) and the angular spectrum approach (ASA). The shear waves induced by the acoustic radiation force are then simulated in elastic and viscoelastic media using Green's functions. A parallel algorithm is developed to perform these calculations on a GPU, where the shear wave particle displacements at different observation points are calculated in parallel. The resulting speed increase enables rapid evaluation of shear waves at discrete points, in 2D planes, and for push beams with different spatial samplings and for different values of the f-number (f/#). The results of these simulations show that push beams with smaller f/# require a higher spatial sampling rate. The significant amount of acceleration achieved by this approach suggests that shear wave simulations with the Green's function approach are ideally suited for high-performance GPUs. Shear wave elasticity imaging determines the mechanical parameters of soft tissue by analyzing measured shear waves induced by an acoustic radiation force. To estimate the shear elasticity value, the widely used time-of-flight method calculates the correlation between shear wave particle velocities at adjacent lateral observation points. Although this method provides accurate estimates of the shear elasticity in purely elastic media, our experience suggests that the time-of-flight (TOF) method consistently overestimates the shear elasticity values in viscoelastic media because the combined effects of diffraction, attenuation, and dispersion are not considered. To address this problem, we have developed an approach that directly accounts for all

Shear machines

International Nuclear Information System (INIS)

Astill, M.; Sunderland, A.; Waine, M.G.

1980-01-01

A shear machine for irradiated nuclear fuel elements has a replaceable shear assembly comprising a fuel element support block, a shear blade support and a clamp assembly which hold the fuel element to be sheared in contact with the support block. A first clamp member contacts the fuel element remote from the shear blade and a second clamp member contacts the fuel element adjacent the shear blade and is advanced towards the support block during shearing to compensate for any compression of the fuel element caused by the shear blade (U.K.)

Our Cosmic Insignificance

Science.gov (United States)

Kahane, Guy

2014-01-01

The universe that surrounds us is vast, and we are so very small. When we reflect on the vastness of the universe, our humdrum cosmic location, and the inevitable future demise of humanity, our lives can seem utterly insignificant. Many philosophers assume that such worries about our significance reflect a banal metaethical confusion. They dismiss the very idea of cosmic significance. This, I argue, is a mistake. Worries about cosmic insignificance do not express metaethical worries about objectivity or nihilism, and we can make good sense of the idea of cosmic significance and its absence. It is also possible to explain why the vastness of the universe can make us feel insignificant. This impression does turn out to be mistaken, but not for the reasons typically assumed. In fact, we might be of immense cosmic significance—though we cannot, at this point, tell whether this is the case. PMID:25729095

A cosmic microwave background feature consistent with a cosmic texture.

Science.gov (United States)

Cruz, M; Turok, N; Vielva, P; Martínez-González, E; Hobson, M

2007-12-07

The Cosmic Microwave Background provides our most ancient image of the universe and our best tool for studying its early evolution. Theories of high-energy physics predict the formation of various types of topological defects in the very early universe, including cosmic texture, which would generate hot and cold spots in the Cosmic Microwave Background. We show through a Bayesian statistical analysis that the most prominent 5 degrees -radius cold spot observed in all-sky images, which is otherwise hard to explain, is compatible with having being caused by a texture. From this model, we constrain the fundamental symmetry-breaking energy scale to be (0) approximately 8.7 x 10(15) gigaelectron volts. If confirmed, this detection of a cosmic defect will probe physics at energies exceeding any conceivable terrestrial experiment.

Cosmic Microwave Background Timeline

Science.gov (United States)

Cosmic Microwave Background Timeline 1934 : Richard Tolman shows that blackbody radiation in an will have a blackbody cosmic microwave background with temperature about 5 K 1955: Tigran Shmaonov anisotropy in the cosmic microwave background, this strongly supports the big bang model with gravitational

Light scattering by cosmic particles

NARCIS (Netherlands)

Hovenier, J.W.; Min, M.

2008-01-01

We define cosmic particles as particles outside the Earth. Two types of cosmic particles can be distinguished, namely liquid and solid particles. The solid particles are often called grains or cosmic dust particles. Cosmic particles occur in a great variety of astronomical objects and environments.

Cosmic strings and galaxy formation

International Nuclear Information System (INIS)

Bertschinger, E.

1989-01-01

Cosmic strings have become increasingly popular candidates as seeds for the formation of structure in the universe. This scenario, remains a serious cosmogonical model despite close scrutiny. In constrast, magnetic monopoles and domain walls - relic topological defects as are cosmic strings - are disastrous for cosmology if they are left over from the early universe. The production of heavy cosmic strings is speculative, as it depends on the details of ultrahigh energy physics. Fortunately, speculation about cosmic strings is not entirely idle because, if they exist and are heavy enough to seed galaxy formation, cosmic strings can be detected astronomically. Failure to detect cosmic strings would impose some constraints on grand unified theories (GUTs); their discovery would have exciting consequences for high energy physics and cosmology. This article reviews the basic physics of nonsuperconducting cosmic strings, highlighting the field theory aspects, and provides a progress report on calculations of structure formation with cosmic strings

Calculation of cosmic ray induced single event upsets: Program CRUP (Cosmic Ray Upset Program)

Science.gov (United States)

Shapiro, P.

1983-09-01

This report documents PROGRAM CRUP, COSMIC RAY UPSET PROGRAM. The computer program calculates cosmic ray induced single-event error rates in microelectronic circuits exposed to several representative cosmic-ray environments.

Transdimensional Bayesian tomography of the lowermost mantle from shear waves

Science.gov (United States)

Richardson, C.; Mousavi, S. S.; Tkalcic, H.; Masters, G.

2017-12-01

The lowermost layer of the mantle, known as D'', is a complex region that contains significant heterogeneities on different spatial scales and a wide range of physical and chemical features such as partial melting, seismic anisotropy, and variations in thermal and chemical composition. The most powerful tools we have to probe this region are seismic waves and corresponding imaging techniques such as tomography. Recently, we developed compressional velocity tomograms of D'' using a transdimensional Bayesian inversion, where the model parameterization is not explicit and regularization is not required. This has produced a far more nuanced P-wave velocity model of D'' than that from traditional S-wave tomography. We also note that P-wave models of D'' vary much more significantly among various research groups than the corresponding S-wave models. This study therefore seeks to develop a new S-wave velocity model of D'' underneath Australia by using predominantly ScS-S differential travel times measured through waveform correlation and Bayesian transdimensional inversion to further understand and characterize heterogeneities in D''. We used events at epicentral distances between 45 and 75 degrees from stations in Australia at depths of over 200 km and with magnitudes between 6.0 and 6.7. Because of globally incomplete coverage of station and earthquake locations, a major limitation of deep earth tomography has been the explicit parameterization of the region of interest. Explicit parameterization has been foundational in most studies, but faces inherent problems of either over-smoothing the data, or allowing for too much noise. To avoid this, we use spherical Voronoi polygons, which allow for a high level of flexibility as the polygons can grow, shrink, or be altogether deleted throughout a sequence of iterations. Our technique also yields highly desired model parameter uncertainties. While there is little doubt that D'' is heterogeneous, there is still much that is

Multi-Channel Optical Coherence Elastography Using Relative and Absolute Shear-Wave Time of Flight

DEFF Research Database (Denmark)

Elyas, Eli; Grimwood, Alex; Erler, Janine Terra

2017-01-01

a commercial four-channel swept-source OCT system. Shear-wave time of arrival (TOA) was detected by tracking the axial OCT-speckle motion using cross-correlation methods. Shear-wave speed was then calculated from inter-channel differences of TOA for a single burst (the relative TOA method) and compared......Elastography, the imaging of elastic properties of soft tissues, is well developed for macroscopic clinical imaging of soft tissues and can provide useful information about various pathological processes which is complementary to that provided by the original modality. Scaling down...... of this technique should ply the field of cellular biology with valuable information with regard to elastic properties of cells and their environment. This paper evaluates the potential to develop such a tool by modifying a commercial optical coherence tomography (OCT) device to measure the speed of shear waves...

Cosmic ray diffusion: report of the workshop in cosmic ray diffusion theory

International Nuclear Information System (INIS)

Birmingham, T.J.; Jones, F.C.

1975-02-01

A workshop in cosmic ray diffusion theory was held at Goddard Space Flight Center on May 16-17, 1974. Topics discussed and summarized are: (1) cosmic ray measurements as related to diffusion theory; (2) quasi-linear theory, nonlinear theory, and computer simulation of cosmic ray pitch-angle diffusion; and (3) magnetic field fluctuation measurements as related to diffusion theory. (auth)

11. European cosmic ray symposium

International Nuclear Information System (INIS)

1989-03-01

The biannual Symposium includes all aspects of cosmic ray research. The scientific programme was organized under three main headings: Cosmic rays in the heliosphere, Cosmic rays in the interstellar and extragalactic space, Properties of high-energy interactions as studied by cosmic rays. Seven invited talks were indexed seprately for the INIS database. (R.P.)

submitter The Muon Portal Project: Design and construction of a scanning portal based on muon tomography

CERN Document Server

Antonuccio, V; Becciani, U; Bonanno, D L; Bonanno, G; Bongiovanni, D; Fallica, P G; Garozzo, S; Grillo, A; La Rocca, P; Leonora, E; Longhitano, F; Lo Presti, D; Marano, D; Parasole, O; Pugliatti, C; Randazzo, N; Riggi, F; Riggi, S; Romeo, G; Romeo, M; Russo, G V; Santagati, G; Timpanaro, M C; Valvo, G

2017-01-01

Cosmic ray tomography is a technique which exploits the multiple Coulomb scattering of highly penetrating cosmic ray-produced muons to perform non-destructive inspection of high-Z materials without the use of artificial radiation. A muon tomography detection system can be used as a portal monitor at border crossing points for detecting illegal targeted objects. The Muon Portal Project is a joint initiative between Italian research and industrial partners, aimed at the construction of a real size detector prototype $(6×3×7 m^3)$ for the inspection of cargo containers by the muon scattering technique. The detector consists of four XY tracking planes, two placed above and two below the container to be inspected. After a research and development phase, which led to the choice and test of the individual components, the construction and installation of the detection modules is almost completed. In this paper the present status of the Project is reported, focusing on the design and construction phase, as well as o...

A COSMIC VARIANCE COOKBOOK

International Nuclear Information System (INIS)

Moster, Benjamin P.; Rix, Hans-Walter; Somerville, Rachel S.; Newman, Jeffrey A.

2011-01-01

Deep pencil beam surveys ( 2 ) are of fundamental importance for studying the high-redshift universe. However, inferences about galaxy population properties (e.g., the abundance of objects) are in practice limited by 'cosmic variance'. This is the uncertainty in observational estimates of the number density of galaxies arising from the underlying large-scale density fluctuations. This source of uncertainty can be significant, especially for surveys which cover only small areas and for massive high-redshift galaxies. Cosmic variance for a given galaxy population can be determined using predictions from cold dark matter theory and the galaxy bias. In this paper, we provide tools for experiment design and interpretation. For a given survey geometry, we present the cosmic variance of dark matter as a function of mean redshift z-bar and redshift bin size Δz. Using a halo occupation model to predict galaxy clustering, we derive the galaxy bias as a function of mean redshift for galaxy samples of a given stellar mass range. In the linear regime, the cosmic variance of these galaxy samples is the product of the galaxy bias and the dark matter cosmic variance. We present a simple recipe using a fitting function to compute cosmic variance as a function of the angular dimensions of the field, z-bar , Δz, and stellar mass m * . We also provide tabulated values and a software tool. The accuracy of the resulting cosmic variance estimates (δσ v /σ v ) is shown to be better than 20%. We find that for GOODS at z-bar =2 and with Δz = 0.5, the relative cosmic variance of galaxies with m * >10 11 M sun is ∼38%, while it is ∼27% for GEMS and ∼12% for COSMOS. For galaxies of m * ∼ 10 10 M sun , the relative cosmic variance is ∼19% for GOODS, ∼13% for GEMS, and ∼6% for COSMOS. This implies that cosmic variance is a significant source of uncertainty at z-bar =2 for small fields and massive galaxies, while for larger fields and intermediate mass galaxies, cosmic

Cosmic Accelerators: An Introduction

International Nuclear Information System (INIS)

Kanbach, Gottfried

2005-01-01

High energy, relativistic, particles are an essential component of the Universe and play a major role in astrophysics. In a few years we will reach the centennial of the discovery of cosmic rays; all through this century the properties, origin, and effects of this radiation have intrigued researchers in astrophysics and elementary particles alike. We briefly review the history, current status, and future perspectives of cosmic ray research. Emphasis will be placed on the multitude of cosmic accelerators, direct observations of these objects, and the effects of cosmic rays in the Galaxy and beyond

High energy cosmic rays

CERN Document Server

Stanev, Todor

2010-01-01

Offers an accessible text and reference (a cosmic-ray manual) for graduate students entering the field and high-energy astrophysicists will find this an accessible cosmic-ray manual Easy to read for the general astronomer, the first part describes the standard model of cosmic rays based on our understanding of modern particle physics. Presents the acceleration scenario in some detail in supernovae explosions as well as in the passage of cosmic rays through the Galaxy. Compares experimental data in the atmosphere as well as underground are compared with theoretical models

High Energy Cosmic Electrons: Messengers from Nearby Cosmic Ray Sources or Dark Matter?

Science.gov (United States)

Moiseev, Alexander

2011-01-01

This slide presentation reviews the recent discoveries by the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-Ray Telescope in reference to high energy cosmic electrons, and whether their source is cosmic rays or dark matter. Specific interest is devoted to Cosmic Ray electrons anisotropy,

Shear-wave velocities beneath the Harrat Rahat volcanic field, Saudi Arabia, using ambient seismic noise analysis

Science.gov (United States)

Civilini, F.; Mooney, W.; Savage, M. K.; Townend, J.; Zahran, H. M.

2017-12-01

We present seismic shear-velocities for Harrat Rahat, a Cenozoic bimodal alkaline volcanic field in west-central Saudi Arabia, using seismic tomography from natural ambient noise. This project is part of an overall effort by the Saudi Geological Survey and the United States Geological Survey to describe the subsurface structure and assess hazards within the Saudi Arabian shield. Volcanism at Harrat Rahat began approximately 10 Ma, with at least three pulses around 10, 5, and 2 Ma, and at least several pulses in the Quaternary from 1.9 Ma to the present. This area is instrumented by 14 broadband Nanometrics Trillium T120 instruments across an array aperture of approximately 130 kilometers. We used a year of recorded natural ambient noise to determine group and phase velocity surface wave dispersion maps with a 0.1 decimal degree resolution for radial-radial, transverse-transverse, and vertical-vertical components of the empirical Green's function. A grid-search method was used to carry out 1D shear-velocity inversions at each latitude-longitude point and the results were interpolated to produce pseudo-3D shear velocity models. The dispersion maps resolved a zone of slow surface wave velocity south-east of the city of Medina spatially correlated with the 1256 CE eruption. A crustal layer interface at approximately 20 km depth was determined by the inversions for all components, matching the results of prior seismic-refraction studies. Cross-sections of the 3D shear velocity models were compared to gravity measurements obtained in the south-east edge of the field. We found that measurements of low gravity qualitatively correlate with low values of shear-velocity below 20 km along the cross-section profile. We apply these methods to obtain preliminary tomography results on the entire Arabian Shield.

Cosmic strings

International Nuclear Information System (INIS)

Bennett, D.P.

1988-07-01

Cosmic strings are linear topological defects that are predicted by some grand unified theories to form during a spontaneous symmetry breaking phase transition in the early universe. They are the basis for the only theories of galaxy formation aside from quantum fluctuations from inflation that are based on fundamental physics. In contrast to inflation, they can also be observed directly through gravitational lensing and their characteristic microwave background anistropy. It has recently been discovered by F. Bouchet and myself that details of cosmic string evolution are very different from the so-called ''standard model'' that has been assumed in most of the string induced galaxy formation calculations. Therefore, the details of galaxy formation in the cosmic string models are currently very uncertain. 29 refs., 9 figs

3D imaging of vesicles in hyaloclastic fragments - clues to syn-eruptive shear conditions

Science.gov (United States)

Helo, C.; Flaws, A.; Hess, K.; Franz, A.; Clague, D. A.; Dingwell, D. B.

2011-12-01

3D imaging of stretched vesicles in hyaloclastic fragments has been used to investigate the shear environment of mild pyroclastic eruptions at mid-ocean ridges. X-ray computed tomography offers an attractive non-invasive method to investigate geomaterials at a high resolution for the geometry of the different phases. In this study, we have imaged vesicles within two types of basaltic glass fragments. Stretched, ellipsoid-shaped vesicles in thin limu o Pele and tubular vesicles in a pumiceous fragment. Both types originate from pyroclastic activity on Axial Seamount, Juan de Fuca ridge. Rapid quenching of the glass has prevented extensive bubble relaxation and information about syn-eruptive shear and differential stress conditions is stored, as the dimensions of a stretched bubble directly relates to the extent and mode of shearing. The X-ray tomography data was processed using a set of codes based on edge detection and ellipsoid fitting to acquire quantitative information on the shape of the stretched vesicles. Preliminary results demonstrate, that the geometry of the stretched vesicles, e.g., the elongation of the vesicle with respect to the calculated undeformed radius, is in accordance with simple shear scenarios. Stored differential stress ranges from 5 kPa to 90 kPa with shear rates between 3.2x102 s-1 and 5.7x3 s-1 within a single limu o Pele fragment. This range may be explained by either variable time available for relaxation as the cooling front proceeds through the fragment, complex interplay in space and time between fragmentation and quenching, bubble clusters mutually inhibiting each others extend of deformation, or any combination of these. Bubble relaxation time scales are less then 0.005 s providing constraints on the timeframe for cooling to the glass transition. Qualitative analyses of the tube pumice indicates that the tubular structures grow in length by coalescence of vertically aligned ellipsoid-shaped vesicles, and in width by coalescence of

Shear Resistance Variations in Experimentally Sheared Mudstone Granules: A Possible Shear-Thinning and Thixotropic Mechanism

Science.gov (United States)

Hu, Wei; Xu, Qiang; Wang, Gonghui; Scaringi, Gianvito; Mcsaveney, Mauri; Hicher, Pierre-Yves

2017-11-01

We present results of ring shear frictional resistance for mudstone granules of different size obtained from a landslide shear zone. Little rate dependency of shear resistance was observed in sand-sized granules in any wet or dry test, while saturated gravel-sized granules exhibited significant and abrupt reversible rate-weakening (from μ = 0.6 to 0.05) at about 2 mm/s. Repeating resistance variations occurred also under constant shear displacement rate. Mudstone granules generate mud as they are crushed and softened. Shear-thinning and thixotropic behavior of the mud can explain the observed behavior: with the viscosity decreasing, the mud can flow through the coarser soil pores and migrate out from the shear zone. This brings new granules into contact which produces new mud. Thus, the process can start over. Similarities between experimental shear zones and those of some landslides in mudstone suggest that the observed behavior may play a role in some landslide kinematics.

Cosmic-Ray Extremely Distributed Observatory: a global cosmic ray detection framework

Science.gov (United States)

Sushchov, O.; Homola, P.; Dhital, N.; Bratek, Ł.; Poznański, P.; Wibig, T.; Zamora-Saa, J.; Almeida Cheminant, K.; Alvarez Castillo, D.; Góra, D.; Jagoda, P.; Jałocha, J.; Jarvis, J. F.; Kasztelan, M.; Kopański, K.; Krupiński, M.; Michałek, M.; Nazari, V.; Smelcerz, K.; Smolek, K.; Stasielak, J.; Sułek, M.

2017-12-01

The main objective of the Cosmic-Ray Extremely Distributed Observatory (CREDO) is the detection and analysis of extended cosmic ray phenomena, so-called super-preshowers (SPS), using existing as well as new infrastructure (cosmic-ray observatories, educational detectors, single detectors etc.). The search for ensembles of cosmic ray events initiated by SPS is yet an untouched ground, in contrast to the current state-of-the-art analysis, which is focused on the detection of single cosmic ray events. Theoretical explanation of SPS could be given either within classical (e.g., photon-photon interaction) or exotic (e.g., Super Heavy Dark Matter decay or annihilation) scenarios, thus detection of SPS would provide a better understanding of particle physics, high energy astrophysics and cosmology. The ensembles of cosmic rays can be classified based on the spatial and temporal extent of particles constituting the ensemble. Some classes of SPS are predicted to have huge spatial distribution, a unique signature detectable only with a facility of the global size. Since development and commissioning of a completely new facility with such requirements is economically unwarranted and time-consuming, the global analysis goals are achievable when all types of existing detectors are merged into a worldwide network. The idea to use the instruments in operation is based on a novel trigger algorithm: in parallel to looking for neighbour surface detectors receiving the signal simultaneously, one should also look for spatially isolated stations clustered in a small time window. On the other hand, CREDO strategy is also aimed at an active engagement of a large number of participants, who will contribute to the project by using common electronic devices (e.g., smartphones), capable of detecting cosmic rays. It will help not only in expanding the geographical spread of CREDO, but also in managing a large manpower necessary for a more efficient crowd-sourced pattern recognition scheme to

Cosmic rays in space

International Nuclear Information System (INIS)

Fujitaka, Kazunobu

2005-01-01

Cosmos is a mysterious space by which many researchers are fascinated for many years. But, going into space means that we will receive extra exposure due to existence of cosmic rays. Cosmic rays are mainly composed of highly energetic protons. It was born in the last stage of stellar life. Understanding of cosmos will certainly bring right understanding of radiation energy, or energy itself. As no one could see the very early stage of cosmic rays, there is only a speculation. But it is better to speculate something based on certain side evidences, than to give up the whole. Such attitude shall be welcomed in the space researches. Anyway, cosmic rays were born in the last explosion of a star, which is called as Super Nova. After cosmic rays are emitted from the Super Nova, it will reach to the human surroundings. To indicate its intensity, special unit of ''dose rate'' is used. When a man climbs a mountain, cosmic ray intensity surely increases. It doubles as he goes up every 1500m elevation. It was ascertained by our own measurements. Then what happens when the goes up more? At aviation altitude, where airplanes fly, the dose rate will be increased up to 100times the high mountain cases. And what is expected when he goes up further more, up to space orbit altitude? In this case, the dose rate increases up to 10times the airplane cases. Geomagnetism affects the dose rate very much. As primary cosmic ray particles are charged particles, they cannot do well with existence of the magnetic field. In effect, cosmic rays can penetrate into the polar atmosphere along geomagnetic lines of forces which stand almost vertical, but penetration of low energy cosmic rays will be banned when they intend to penetrate crossing the geomagnetic lines of forces in equatorial region. Therefore, exposure due to cosmic rays will become large in polar region, while it remains small in equatorial region. In effect, airplanes which fly over the equator. Only, we have to know that the cosmos

Cosmic ray: Studying the origin

International Nuclear Information System (INIS)

Szabelski, J.

1997-01-01

Investigations of the origin of cosmic rays are presented. Different methods are discussed: studies of cosmic gamma rays of energy from 30 MeV to about 10 15 eV (since photons point to their places of origin), studies of the mass composition of cosmic rays (because it reflects source morphology), and studies of cosmic rays with energy above 1O 19 eV (for these are the highest energies observed in nature). (author)

Constraints on cosmic strings due to black holes formed from collapsed cosmic string loops

International Nuclear Information System (INIS)

Caldwell, R.R.; Gates, E.

1993-05-01

The cosmological features of primordial black holes formed from collapsed cosmic string loops are studied. Observational restrictions on a population of primordial black holes are used to restrict f, the fraction of cosmic string loops which collapse to form black holes, and μ, the cosmic string mass-per-unit-length. Using a realistic model of cosmic strings, we find the strongest restriction on the parameters f and μ is due to the energy density in 100MeV photons radiated by the black holes. We also find that inert black hole remnants cannot serve as the dark matter. If earlier, crude estimates of f are reliable, our results severely restrict μ, and therefore limit the viability of the cosmic string large-scale structure scenario

D-term inflation, cosmic strings, and consistency with cosmic microwave background measurements.

Science.gov (United States)

Rocher, Jonathan; Sakellariadou, Mairi

2005-01-14

Standard D-term inflation is studied in the framework of supergravity. D-term inflation produces cosmic strings; however, it can still be compatible with cosmic microwave background (CMB) measurements without invoking any new physics. The cosmic strings contribution to the CMB data is not constant, nor dominant, contrary to some previous results. Using current CMB measurements, the free parameters (gauge and superpotential couplings, as well as the Fayet-Iliopoulos term) of D-term inflation are constrained.

The Muon Portal Project: Design and construction of a scanning portal based on muon tomography

Energy Technology Data Exchange (ETDEWEB)

Antonuccio, V. [INAF - Osservatorio Astrofisico di Catania (Italy); Bandieramonte, M. [CERN, Geneva (Switzerland); Becciani, U. [INAF - Osservatorio Astrofisico di Catania (Italy); Bonanno, D.L., E-mail: danilo.bonanno@ct.infn.it [INFN Sezione di Catania, Catania (Italy); Bonanno, G. [INAF - Osservatorio Astrofisico di Catania (Italy); Bongiovanni, D. [INFN Sezione di Catania, Catania (Italy); Fallica, P.G. [STMicroelectronics, Catania (Italy); Garozzo, S.; Grillo, A. [INAF - Osservatorio Astrofisico di Catania (Italy); La Rocca, P. [INFN Sezione di Catania, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); Leonora, E.; Longhitano, F. [INFN Sezione di Catania, Catania (Italy); Lo Presti, D. [INFN Sezione di Catania, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); Marano, D. [INAF - Osservatorio Astrofisico di Catania (Italy); Parasole, O. [INFN Sezione di Catania, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); Pugliatti, C. [Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); Randazzo, N. [INFN Sezione di Catania, Catania (Italy); Riggi, F. [INFN Sezione di Catania, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); Riggi, S. [INAF - Osservatorio Astrofisico di Catania (Italy); INFN Sezione di Catania, Catania (Italy); Romeo, G. [INAF - Osservatorio Astrofisico di Catania (Italy); and others

2017-02-11

Cosmic ray tomography is a technique which exploits the multiple Coulomb scattering of highly penetrating cosmic ray-produced muons to perform non-destructive inspection of high-Z materials without the use of artificial radiation. A muon tomography detection system can be used as a portal monitor at border crossing points for detecting illegal targeted objects. The Muon Portal Project is a joint initiative between Italian research and industrial partners, aimed at the construction of a real size detector prototype (6×3×7 m{sup 3}) for the inspection of cargo containers by the muon scattering technique. The detector consists of four XY tracking planes, two placed above and two below the container to be inspected. After a research and development phase, which led to the choice and test of the individual components, the construction and installation of the detection modules is almost completed. In this paper the present status of the Project is reported, focusing on the design and construction phase, as well as on the preliminary results obtained with the first detection planes.

The Muon Portal Project: Design and construction of a scanning portal based on muon tomography

Science.gov (United States)

Antonuccio, V.; Bandieramonte, M.; Becciani, U.; Bonanno, D. L.; Bonanno, G.; Bongiovanni, D.; Fallica, P. G.; Garozzo, S.; Grillo, A.; La Rocca, P.; Leonora, E.; Longhitano, F.; Lo Presti, D.; Marano, D.; Parasole, O.; Pugliatti, C.; Randazzo, N.; Riggi, F.; Riggi, S.; Romeo, G.; Romeo, M.; Russo, G. V.; Santagati, G.; Timpanaro, M. C.; Valvo, G.

2017-02-01

Cosmic ray tomography is a technique which exploits the multiple Coulomb scattering of highly penetrating cosmic ray-produced muons to perform non-destructive inspection of high-Z materials without the use of artificial radiation. A muon tomography detection system can be used as a portal monitor at border crossing points for detecting illegal targeted objects. The Muon Portal Project is a joint initiative between Italian research and industrial partners, aimed at the construction of a real size detector prototype (6×3×7 m3) for the inspection of cargo containers by the muon scattering technique. The detector consists of four XY tracking planes, two placed above and two below the container to be inspected. After a research and development phase, which led to the choice and test of the individual components, the construction and installation of the detection modules is almost completed. In this paper the present status of the Project is reported, focusing on the design and construction phase, as well as on the preliminary results obtained with the first detection planes.

Development of a tomographic method using cosmic ray muons: application to the Mont Terri underground laboratory and la Soufriere de Guadeloupe

International Nuclear Information System (INIS)

Lesparre, N.

2011-01-01

Cosmic muons are produced in cascade processes following the interactions of cosmic rays with the atmosphere. Muons are fundamental particles with a mass 200 times higher than electrons. Their low interaction probability with matter allows them to cross the atmosphere and even the first kilometers of the Earth crust. The muons flux is attenuated through a media as function of the quantity of matter crossed. The study of the muon flux attenuation allows then to obtain a direct measurement of the rock opacity. This opacity corresponds to the media density, integrated along the muon path through rock. Muons' trajectory is indeed considered to be straight when crossing rock. It is then possible to realise geophysical tomographies by setting a sensor network around geological objects in order to determine the internal structures geometry inside these objects. An underground muon flux model is developed herein from flux models estimated at surface and a model of muon flux attenuation through rock. A feasibility equation of the muon tomography is then established in order to determine the minimum time of data acquisition to distinguish heterogeneities. Four muons telescopes have been built during this thesis and conditioned to bear field installation, notably in tropical media. These telescopes are made by two or three matrices of detection constituted of scintillating bars linked to photomultipliers. The modeling of the telescopes detection capacity and angular resolution is realised as function of their geometrical configuration. A calibration method is also established in order to correct the signal from any distortion. Moreover, arrangements to reduce the backward noise produced by low energy particles are set up and evaluated. The development of this new tomographic method is then illustrated by two geophysical applications. The measurements realised in the Mont Terri underground laboratory (Switzerland) allowed us to benefit from stable acquisition conditions to

Cosmic ray modulation

International Nuclear Information System (INIS)

Ueno, Hirosachi

1974-01-01

It is important to know the physical state of solar plasma region by the observation of intensity variation of cosmic ray which passed through the solar plasma region, because earth magnetosphere is formed by the interaction between geomagnetic field and solar plasma flow. The observation of cosmic ray intensity is useful to know the average condition of the space of 0.1--3 A.U., and gives the structure of the magnetic field in solar wind affecting the earth magnetosphere. The observation of neutron component in cosmic ray has been carried out at Norikura, Tokyo, Fukushima and Morioka. The lower limit of the energy of incident cosmic ray which can be observed at each station is different, and the fine structure of the variation can be known by comparison. The intensity of meson component in cosmic ray has been measured in underground, and the state of solar plasma region 2--3 A.U. from the earth can be known. The underground measurement has been made at Takeyama and Matsumoto, and a new station at Sakashita is proposed. The measurement at Sakashita will be made by proportional counters at the depth of 100m (water equivalent). Arrangement of detectors is shown. (Kato, T.)

Computational fluid dynamics comparisons of wall shear stress in patient-specific coronary artery bifurcation using coronary angiography and optical coherence tomography

Science.gov (United States)

Poon, Eric; Thondapu, Vikas; Chin, Cheng; Scheerlinck, Cedric; Zahtila, Tony; Mamon, Chris; Nguyen, Wilson; Ooi, Andrew; Barlis, Peter

2016-11-01

Blood flow dynamics directly influence biology of the arterial wall, and are closely linked with the development of coronary artery disease. Computational fluid dynamics (CFD) solvers may be employed to analyze the hemodynamic environment in patient-specific reconstructions of coronary arteries. Although coronary X-ray angiography (CA) is the most common medical imaging modality for 3D arterial reconstruction, models reconstructed from CA assume a circular or elliptical cross-sectional area. This limitation can be overcome with a reconstruction technique fusing CA with intravascular optical coherence tomography (OCT). OCT scans the interior of an artery using near-infrared light, achieving a 10-micron resolution and providing unprecedented detail of vessel geometry. We compared 3D coronary artery bifurcation models generated using CA alone versus OCT-angiography fusion. The model reconstructed from CA alone is unable to identify the detailed geometrical variations of diseased arteries, and also under-estimates the cross-sectional vessel area compared to OCT-angiography fusion. CFD was performed in both models under pulsatile flow in order to identify and compare regions of low wall shear stress, a hemodynamic parameter directly linked with progression of atherosclerosis. Supported by ARC LP150100233 and VLSCI VR0210.

Cosmic Humanity: Utopia, Realities, Prospects

OpenAIRE

Sergey Krichevsky

2017-01-01

The philosophical foundations of the theory and practice of the creation of cosmic humanity as a process of the evolution of human civilization, the emergence into space, with the prospect of resettlement outside the Earth are considered. There is a connection between myths, fantasies, ideas, concepts and projects aimed at the exploration of outer space, the creation of cosmic humanity. A new and voluminous definition of cosmic humanity in the evolutionary paradigm is given. Cosmic humanity i...

Cosmic-ray-veto detector system

International Nuclear Information System (INIS)

Miller, D.W.; Menlove, H.O.

1992-12-01

To reduce the cosmic-ray-induced neutron background, we are testing a cosmic-ray veto option with a neutron detector system that uses plastic scintillator slabs mounted on the outside of a 3 He-tube detector. The scintillator slabs eliminate unwanted cosmic-ray events, enabling the detector to assay low-level plutonium samples, for which a low-background coincident signature is critical. This report describes the design and testing of the prototype cosmic-ray-veto detector system

Study on shear properties of coral sand under cyclic simple shear condition

Science.gov (United States)

Ji, Wendong; Zhang, Yuting; Jin, Yafei

2018-05-01

In recent years, the ocean development in our country urgently needs to be accelerated. The construction of artificial coral reefs has become an important development direction. In this paper, experimental studies of simple shear and cyclic simple shear of coral sand are carried out, and the shear properties and particle breakage of coral sand are analyzed. The results show that the coral sand samples show an overall shear failure in the simple shear test, which is more accurate and effective for studying the particle breakage. The shear displacement corresponding to the peak shear stress of the simple shear test is significantly larger than that corresponding to the peak shear stress of the direct shear test. The degree of particle breakage caused by the simple shear test is significantly related to the normal stress level. The particle breakage of coral sand after the cyclic simple shear test obviously increases compared with that of the simple shear test, and universal particle breakage occurs within the whole particle size range. The increasing of the cycle-index under cyclic simple shear test results in continuous compacting of the sample, so that the envelope curve of peak shearing force increases with the accumulated shear displacement.

GEANT4 simulation of a scintillating-fibre tracker for the cosmic-ray muon tomography of legacy nuclear waste containers

Energy Technology Data Exchange (ETDEWEB)

Clarkson, A.; Hamilton, D.J.; Hoek, M.; Ireland, D.G. [SUPA, School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow G12 8QQ, Scotland (United Kingdom); Johnstone, J.R. [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale, Cumbria CA20 1PG, England (United Kingdom); Kaiser, R.; Keri, T.; Lumsden, S. [SUPA, School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow G12 8QQ, Scotland (United Kingdom); Mahon, D.F., E-mail: David.Mahon@Glasgow.ac.uk [SUPA, School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow G12 8QQ, Scotland (United Kingdom); McKinnon, B.; Murray, M.; Nutbeam-Tuffs, S. [SUPA, School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow G12 8QQ, Scotland (United Kingdom); Shearer, C.; Staines, C. [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale, Cumbria CA20 1PG, England (United Kingdom); Yang, G. [SUPA, School of Physics and Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow G12 8QQ, Scotland (United Kingdom); Zimmerman, C. [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale, Cumbria CA20 1PG, England (United Kingdom)

2014-05-11

Cosmic-ray muons are highly penetrative charged particles that are observed at the sea level with a flux of approximately one per square centimetre per minute. They interact with matter primarily through Coulomb scattering, which is exploited in the field of muon tomography to image shielded objects in a wide range of applications. In this paper, simulation studies are presented that assess the feasibility of a scintillating-fibre tracker system for use in the identification and characterisation of nuclear materials stored within industrial legacy waste containers. A system consisting of a pair of tracking modules above and a pair below the volume to be assayed is simulated within the GEANT4 framework using a range of potential fibre pitches and module separations. Each module comprises two orthogonal planes of fibres that allow the reconstruction of the initial and Coulomb-scattered muon trajectories. A likelihood-based image reconstruction algorithm has been developed that allows the container content to be determined with respect to the scattering density λ, a parameter which is related to the atomic number Z of the scattering material. Images reconstructed from this simulation are presented for a range of anticipated scenarios that highlight the expected image resolution and the potential of this system for the identification of high-Z materials within a shielded, concrete-filled container. First results from a constructed prototype system are presented in comparison with those from a detailed simulation. Excellent agreement between experimental data and simulation is observed showing clear discrimination between the different materials assayed throughout.

GEANT4 simulation of a scintillating-fibre tracker for the cosmic-ray muon tomography of legacy nuclear waste containers

Science.gov (United States)

Clarkson, A.; Hamilton, D. J.; Hoek, M.; Ireland, D. G.; Johnstone, J. R.; Kaiser, R.; Keri, T.; Lumsden, S.; Mahon, D. F.; McKinnon, B.; Murray, M.; Nutbeam-Tuffs, S.; Shearer, C.; Staines, C.; Yang, G.; Zimmerman, C.

2014-05-01

Cosmic-ray muons are highly penetrative charged particles that are observed at the sea level with a flux of approximately one per square centimetre per minute. They interact with matter primarily through Coulomb scattering, which is exploited in the field of muon tomography to image shielded objects in a wide range of applications. In this paper, simulation studies are presented that assess the feasibility of a scintillating-fibre tracker system for use in the identification and characterisation of nuclear materials stored within industrial legacy waste containers. A system consisting of a pair of tracking modules above and a pair below the volume to be assayed is simulated within the GEANT4 framework using a range of potential fibre pitches and module separations. Each module comprises two orthogonal planes of fibres that allow the reconstruction of the initial and Coulomb-scattered muon trajectories. A likelihood-based image reconstruction algorithm has been developed that allows the container content to be determined with respect to the scattering density λ, a parameter which is related to the atomic number Z of the scattering material. Images reconstructed from this simulation are presented for a range of anticipated scenarios that highlight the expected image resolution and the potential of this system for the identification of high-Z materials within a shielded, concrete-filled container. First results from a constructed prototype system are presented in comparison with those from a detailed simulation. Excellent agreement between experimental data and simulation is observed showing clear discrimination between the different materials assayed throughout.

Shear strength of non-shear reinforced concrete elements

DEFF Research Database (Denmark)

Hoang, Cao linh

1997-01-01

The paper deals with the plastic shear strength of non shear reinforced T-beams.The influence of an un-reinforced flange on the shear capacity is investigated by considering a failure mechanism involving crack sliding in the web and a kind of membrane action over an effective width of the flange...

Test particle trajectories near cosmic strings

Indian Academy of Sciences (India)

We present a detailed analysis of the motion of test particle in the gravitational field of cosmic strings in different situations using the Hamilton–Jacobi (H–J) formalism. We have discussed the trajectories near static cosmic string, cosmic string in Brans–Dicke theory and cosmic string in dilaton gravity.

Cosmic ray: Studying the origin

Energy Technology Data Exchange (ETDEWEB)

Szabelski, J. [Cosmic Ray Laboratory, Soltan Institute for Nuclear Studies, Lodz (Poland)

1997-12-31

Investigations of the origin of cosmic rays are presented. Different methods are discussed: studies of cosmic gamma rays of energy from 30 MeV to about 10{sup 15} eV (since photons point to their places of origin), studies of the mass composition of cosmic rays (because it reflects source morphology), and studies of cosmic rays with energy above 1O{sup 19} eV (for these are the highest energies observed in nature). (author) 101 refs, 19 figs, 7 tabs

Department of Cosmic Radiation Physics: Overview

International Nuclear Information System (INIS)

Gawin, J.

1999-01-01

Full text: The Department of Cosmic Ray Physics in Lodz is involved in basic research in the area of high energy physics and cosmic ray physics related to: - Studies of asymptotic properties of hadronic interactions based on the analysis of cosmic ray propagation in the atmosphere. - Experimental and phenomenological studies of Extensive Air Showers induced by cosmic ray particles. - Search for point sources of high energy cosmic rays. - Studies of cosmic ray propagation in the Galaxy and mechanisms of particle acceleration. - Studies of mass composition of cosmic rays in the energy range 10 15 - 10 17 eV. Theoretical and experimental studies of Extensive Air Shower properties are performed mostly based on the results obtained by the Lodz Extensive Air Shower Array. We analysed nearly 100,000 events of energies above 10 15 eV registered by the Lodz hodoscope. We have developed the method of data analysis which allows us to verify different models of cosmic ray mass composition. In our research in high energy cosmic rays we also used experimental data from other collaborating experiments in Karlsruhe, Baksan and THEMISTOCLE. The Lodz group collaborates with many foreign institutes and laboratories in construction and data interpretation of cosmic ray experiments. Our most important partners are: Forschungszentrum in Karlsruhe (Germany), College de France, Institute for Nuclear Studies of the Russian Academy of Science, University of Perpignan and Uppsala University (Sweden). (author)

Department of Cosmic Radiation Physics - Overview

International Nuclear Information System (INIS)

Gawin, J.

1997-01-01

Full text: The Department of Cosmic Ray Physics in Lodz is involved in basic research in the area of high energy physics and cosmic ray physics related to: -Studies of the asymptotic properties of hadronic interactions from the analysis of cosmic ray propagation in the atmosphere. -Studies of structure and properties of Extensive Air Showers induced by cosmic ray particles. -Search for point sources of high energy cosmic rays. -Studies of cosmic ray propagation in the Galaxy and mechanisms of particle acceleration. -Studies of the mass composition of cosmic rays in the energy range 10 15 -10 17 eV. Theoretical and experimental studies of nuclear interactions for energies exceeding those obtained by modern particle accelerators are performed employing results obtained by the Lodz Extensive Air Shower Array. The Lodz hodoscope can register electromagnetic components of cosmic ray showers in the atmosphere as well as muons at two energy thresholds. Data collected by the Lodz array are also used to study mass composition of cosmic rays in the energy range 10 15 - 10 17 eV. The Lodz group collaborates with foreign institutes and laboratories on construction and data interpretation of cosmic ray experiments. Our most important partners are: Forschungszentrum Karlsruhe (Germany), College de France, the Institute for Nuclear Studies of the Russian Academy of Sciences, the University of Durham, and the University of Perpignan. (author)

Deepening Cosmic Education

Science.gov (United States)

Leonard, Gerard

2013-01-01

This article is a special blend of research, theory, and practice, with clear insight into the origins of Cosmic Education and cosmic task, while recalling memories of student explorations in botany, in particular, episodes from Mr. Leonard's teaching. Mr. Leonard speaks of a storytelling curriculum that eloquently puts perspective into dimensions…

Department of Cosmic Radiation Physics: Overview

International Nuclear Information System (INIS)

Szabelski, J.

2000-01-01

Full text: Department of Cosmic Ray Physics in Lodz is involved in basic research in the area of high-energy physics and cosmic ray physics related to: -Studies of asymptotic properties of hadronic interactions based on the analysis of cosmic ray propagation through the atmosphere. -Experimental and phenomenological studies of Extensive Air Showers induced by cosmic ray particles. - Search for high-energy cosmic ray point sources. - Studies of cosmic ray propagation in the Galaxy and particle acceleration mechanisms. -Studies of mass composition of cosmic rays in the energy range 10 15 -10 17 eV. Theoretical and experimental studies of Extensive Air Shower properties are performed mainly on the basis of the results obtained by the Lodz Extensive Air Shower Array. We have analysed nearly 100,000 events of energies above 10 15 eV registered in the Lodz hodoscope. We have developed a method to verify different models of cosmic ray mass composition. The Lodz group collaborates with many foreign institutes and laboratories in construction and data interpretation of cosmic ray experiments. Our most important partners are: Forschungszentrum in Karlsruhe (Germany), College de France, Institute for Nuclear Studies of the Russian Academy of Sciences and Uppsala University (Sweden). (author)

Robust constraint on cosmic textures from the cosmic microwave background.

Science.gov (United States)

Feeney, Stephen M; Johnson, Matthew C; Mortlock, Daniel J; Peiris, Hiranya V

2012-06-15

Fluctuations in the cosmic microwave background (CMB) contain information which has been pivotal in establishing the current cosmological model. These data can also be used to test well-motivated additions to this model, such as cosmic textures. Textures are a type of topological defect that can be produced during a cosmological phase transition in the early Universe, and which leave characteristic hot and cold spots in the CMB. We apply bayesian methods to carry out a rigorous test of the texture hypothesis, using full-sky data from the Wilkinson Microwave Anisotropy Probe. We conclude that current data do not warrant augmenting the standard cosmological model with textures. We rule out at 95% confidence models that predict more than 6 detectable cosmic textures on the full sky.

Detection of the Velocity Shear Effect on the Spatial Distributions of the Galactic Satellites in Isolated Systems

Science.gov (United States)

Lee, Jounghun; Choi, Yun-Young

2015-02-01

We report a detection of the effect of the large-scale velocity shear on the spatial distributions of the galactic satellites around the isolated hosts. Identifying the isolated galactic systems, each of which consists of a single host galaxy and its satellites, from the Seventh Data Release of the Sloan Digital Sky Survey and reconstructing linearly the velocity shear field in the local universe, we measure the alignments between the relative positions of the satellites from their isolated hosts and the principal axes of the local velocity shear tensors projected onto the plane of sky. We find a clear signal that the galactic satellites in isolated systems are located preferentially along the directions of the minor principal axes of the large-scale velocity shear field. Those galactic satellites that are spirals, are brighter, are located at distances larger than the projected virial radii of the hosts, and belong to the spiral hosts yield stronger alignment signals, which implies that the alignment strength depends on the formation and accretion epochs of the galactic satellites. It is also shown that the alignment strength is quite insensitive to the cosmic web environment, as well as the size and luminosity of the isolated hosts. Although this result is consistent with the numerical finding of Libeskind et al. based on an N-body experiment, owing to the very low significance of the observed signals, it remains inconclusive whether or not the velocity shear effect on the satellite distribution is truly universal.

DETECTION OF THE VELOCITY SHEAR EFFECT ON THE SPATIAL DISTRIBUTIONS OF THE GALACTIC SATELLITES IN ISOLATED SYSTEMS

International Nuclear Information System (INIS)

Lee, Jounghun; Choi, Yun-Young

2015-01-01

We report a detection of the effect of the large-scale velocity shear on the spatial distributions of the galactic satellites around the isolated hosts. Identifying the isolated galactic systems, each of which consists of a single host galaxy and its satellites, from the Seventh Data Release of the Sloan Digital Sky Survey and reconstructing linearly the velocity shear field in the local universe, we measure the alignments between the relative positions of the satellites from their isolated hosts and the principal axes of the local velocity shear tensors projected onto the plane of sky. We find a clear signal that the galactic satellites in isolated systems are located preferentially along the directions of the minor principal axes of the large-scale velocity shear field. Those galactic satellites that are spirals, are brighter, are located at distances larger than the projected virial radii of the hosts, and belong to the spiral hosts yield stronger alignment signals, which implies that the alignment strength depends on the formation and accretion epochs of the galactic satellites. It is also shown that the alignment strength is quite insensitive to the cosmic web environment, as well as the size and luminosity of the isolated hosts. Although this result is consistent with the numerical finding of Libeskind et al. based on an N-body experiment, owing to the very low significance of the observed signals, it remains inconclusive whether or not the velocity shear effect on the satellite distribution is truly universal

Department of Cosmic Radiation Physics: Overview

International Nuclear Information System (INIS)

Gawin, J.

1998-01-01

(full text) The Department of Cosmic Ray Physics in Lodz is involved in basic research in the area of high energy physics and cosmic ray physics related to: -Studies of asymptotic properties of hadronic interactions based on the analysis of cosmic ray propagation in the atmosphere. -Studies of the structure and properties of Extensive Air Showers induced by cosmic ray particles. - Search for point sources of high energy cosmic rays. - Studies of cosmic ray propagation in the Galaxy and mechanisms of particle acceleration. - Studies of mass composition of cosmic rays in the energy range l0 15 -10 17 eV. Theoretical and experimental studies of nuclear interactions for energies exceeding those obtained by modern particle accelerators are performed based on the results obtained by the Lodz Extensive Air Shower Array. The Lodz hodoscope can register the electromagnetic component of cosmic ray showers developing in the atmosphere as well as muons of two energy thresholds. Data collected by the Lodz array are also used to study the mass composition of cosmic rays in the energy range 10 15 -10 17 eV. The Lodz group collaborates with many foreign institutes and laboratories in construction and data interpretation of cosmic ray experiments. Our most important partners are: Forschungszentrum Karlsruhe (Germany), College de' France, the Institute for Nuclear Studies of the Russian Academy of Science, the University of Perpignan (France) and Uppsala University (Sweden). (author)

Full-sky Ray-tracing Simulation of Weak Lensing Using ELUCID Simulations: Exploring Galaxy Intrinsic Alignment and Cosmic Shear Correlations

Science.gov (United States)

Wei, Chengliang; Li, Guoliang; Kang, Xi; Luo, Yu; Xia, Qianli; Wang, Peng; Yang, Xiaohu; Wang, Huiyuan; Jing, Yipeng; Mo, Houjun; Lin, Weipeng; Wang, Yang; Li, Shijie; Lu, Yi; Zhang, Youcai; Lim, S. H.; Tweed, Dylan; Cui, Weiguang

2018-01-01

The intrinsic alignment of galaxies is an important systematic effect in weak-lensing surveys, which can affect the derived cosmological parameters. One direct way to distinguish different alignment models and quantify their effects on the measurement is to produce mock weak-lensing surveys. In this work, we use the full-sky ray-tracing technique to produce mock images of galaxies from the ELUCID N-body simulation run with WMAP9 cosmology. In our model, we assume that the shape of the central elliptical galaxy follows that of the dark matter halo, and that of the spiral galaxy follows the halo spin. Using the mock galaxy images, a combination of galaxy intrinsic shape and the gravitational shear, we compare the predicted tomographic shear correlations to the results of the Kilo-Degree Survey (KiDS) and Deep Lens Survey (DLS). We find that our predictions stay between the KiDS and DLS results. We rule out a model in which the satellite galaxies are radially aligned with the center galaxy; otherwise, the shear correlations on small scales are too high. Most importantly, we find that although the intrinsic alignment of spiral galaxies is very weak, they induce a positive correlation between the gravitational shear signal and the intrinsic galaxy orientation (GI). This is because the spiral galaxy is tangentially aligned with the nearby large-scale overdensity, contrary to the radial alignment of the elliptical galaxy. Our results explain the origin of the detected positive GI term in the weak-lensing surveys. We conclude that in future analyses, the GI model must include the dependence on galaxy types in more detail.

Cosmic Ether

CERN Document Server

Tomaschitz, R

1998-01-01

A prerelativistic approach to particle dynamics is explored in an expanding Robertson-Walker cosmology. The receding galactic background provides a distinguished frame of reference and a unique cosmic time. In this context the relativistic, purely geometric space-time concept is criticized. Physical space is regarded as a permeable medium, the cosmic ether, which effects the world-lines of particles and rays. We study in detail a Robertson-Walker universe with linear expansion factor and negatively curved, open three-space; we choose the permeability tensor of the ether in such a way that the semiclassical approximation is exact. Galactic red-shifts depend on the refractive index of the ether. In the local Minkowskian limit the ether causes a time variation of mass, which scales inversely proportional to cosmic time. In the globally geodesic rest frames of galactic observers the ether manifests itself in an unbounded speed of signal transfer, in bifurcations of world-lines, and in time inversion effects.

Cosmic vacuum

International Nuclear Information System (INIS)

Chernin, Artur D

2001-01-01

Recent observational studies of distant supernovae have suggested the existence of cosmic vacuum whose energy density exceeds the total density of all the other energy components in the Universe. The vacuum produces the field of antigravity that causes the cosmological expansion to accelerate. It is this accelerated expansion that has been discovered in the observations. The discovery of cosmic vacuum radically changes our current understanding of the present state of the Universe. It also poses new challenges to both cosmology and fundamental physics. Why is the density of vacuum what it is? Why do the densities of the cosmic energy components differ in exact value but agree in order of magnitude? On the other hand, the discovery made at large cosmological distances of hundreds and thousands Mpc provides new insights into the dynamics of the nearby Universe, the motions of galaxies in the local volume of 10 - 20 Mpc where the cosmological expansion was originally discovered. (reviews of topical problems)

Cosmic vacuum

Energy Technology Data Exchange (ETDEWEB)

Chernin, Artur D [P.K. Shternberg State Astronomical Institute at the M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

2001-11-30

Recent observational studies of distant supernovae have suggested the existence of cosmic vacuum whose energy density exceeds the total density of all the other energy components in the Universe. The vacuum produces the field of antigravity that causes the cosmological expansion to accelerate. It is this accelerated expansion that has been discovered in the observations. The discovery of cosmic vacuum radically changes our current understanding of the present state of the Universe. It also poses new challenges to both cosmology and fundamental physics. Why is the density of vacuum what it is? Why do the densities of the cosmic energy components differ in exact value but agree in order of magnitude? On the other hand, the discovery made at large cosmological distances of hundreds and thousands Mpc provides new insights into the dynamics of the nearby Universe, the motions of galaxies in the local volume of 10 - 20 Mpc where the cosmological expansion was originally discovered. (reviews of topical problems)

Closing CMS to hunt cosmic rays

CERN Multimedia

Claudia Marcelloni

2006-01-01

Every second the Earth is bombarded by billions of cosmic rays and occasionally one of these cosmic particles will collide with the Earth's atmosphere generating a shower of particles known as an 'air shower'. This is similiar to the collisions and subsequent particle showers observed in accelerators such as the LHC. Here the CMS detector is closed so that systems can be tested using muon cosmic rays in the 'Cosmic Challenge'.

Interplanetary cosmic-ray scintillations

Energy Technology Data Exchange (ETDEWEB)

Toptygin, I N; Vasiliev, V N [Kalininskij Sel' skokhozyajstvennyj Inst. (USSR)

1977-05-01

The equation for the two-particles cosmic-ray distribution function is derived by means of the Boltzmann kinetic equation averaging. This equation is valid for arbitrary ratio of regular and random parts of the magnetic field. For small energy particles the guiding-center approximation is used. On the basis of the derived equation the dependence between power spectra of cosmic-ray intensity and random magnetic field is obtained. If power spectra are degree functions for high energy particles (approximately 10 GeV nucleon/sup -1/), then the spectral exponent ..gamma.. of magnetic field lies between rho and rho-2, where rho is the spectral exponent of cosmic-ray power spectra. The experimental data concerning moderate energy particles are in accordance with ..gamma..=rho, which demonstrates that the magnetic fluctuations are isotropic or cosmic-ray space gradient is small near the Earth orbit.

ALICE Cosmic Ray Detector

CERN Multimedia

Fernandez Tellez, A; Martinez Hernandez, M; Rodriguez Cahuantzi, M

2013-01-01

The ALICE underground cavern provides an ideal place for the detection of high energy atmospheric muons coming from cosmic ray showers. ACORDE detects cosmic ray showers by triggering the arrival of muons to the top of the ALICE magnet.

Cosmic Humanity: Utopia, Realities, Prospects

Directory of Open Access Journals (Sweden)

Sergey Krichevsky

2017-07-01

Full Text Available The philosophical foundations of the theory and practice of the creation of cosmic humanity as a process of the evolution of human civilization, the emergence into space, with the prospect of resettlement outside the Earth are considered. There is a connection between myths, fantasies, ideas, concepts and projects aimed at the exploration of outer space, the creation of cosmic humanity. A new and voluminous definition of cosmic humanity in the evolutionary paradigm is given. Cosmic humanity is (essence and 4 stages of evolution: 1. Humanity living on Earth, sensing, knowing, understanding its cosmic origin, relationship with the cosmos and cosmic destiny. 2. Humanity living on Earth, leading aerospace activity for the purposes of exploration and use of aerospace space (Heaven, Space for survival and development. 3. Humanity living on Earth and outside the Earth — in the solar system, preserving the Earth and mastering the Cosmos for survival and development. 4. Humanity, settled and living in the Cosmos. Now humanity is in the process of transition from the second to the third stage. In the process of this evolution, a complex transformation of man and society takes place. The problem-semantic field of cosmic humanity is described and its general model is presented. The meta-goal-setting is the justification of cosmic humanity with the application of the anthropic principle and its “active” super (post anthropic supplement: “Cosmic humanity has an evolutionary purpose to actively manage evolution: change man, humanity and the universe.” The evolution of the “cosmic dream”, goals and technologies of space activities is formalized in the form of a conceptual model. Challenges and negative trends are considered in connection with the crisis of space activity, criticism and attempts to limit the flights of people into space. The prototype of cosmic humanity, its basis and acting model is the cosmonauts’ community. The main

Cosmic Connections:. from Cosmic Rays to Gamma Rays, Cosmic Backgrounds and Magnetic Fields

Science.gov (United States)

Kusenko, Alexander

2013-12-01

Combined data from gamma-ray telescopes and cosmic-ray detectors have produced some new surprising insights regarding intergalactic and galactic magnetic fields, as well as extragalactic background light. We review some recent advances, including a theory explaining the hard spectra of distant blazars and the measurements of intergalactic magnetic fields based on the spectra of distant sources. Furthermore, we discuss the possible contribution of transient galactic sources, such as past gamma-ray bursts and hypernova explosions in the Milky Way, to the observed ux of ultrahigh-energy cosmicrays nuclei. The need for a holistic treatment of gamma rays, cosmic rays, and magnetic fields serves as a unifying theme for these seemingly unrelated phenomena.

Experimental study of shear rate dependence in perpetually sheared granular matter

Science.gov (United States)

Liu, Sophie Yang; Guillard, François; Marks, Benjy; Rognon, Pierre; Einav, Itai

2017-06-01

We study the shear behaviour of various granular materials by conducting novel perpetual simple shear experiments over four orders of magnitude of relatively low shear rates. The newly developed experimental apparatus employed is called "3D Stadium Shear Device" which is an extended version of the 2D Stadium Shear Device [1]. This device is able to provide a non-radial dependent perpetual shear flow and a nearly linear velocity profile between two oppositely moving shear walls. Using this device, we are able to test a large variety of granular materials. Here, we demonstrate the applicability of the device on glass beads (diameter 1 mm, 3 mm, and 14 mm) and rice. We particularly focus on studying these materials at very low inertial number I ranging from 10-6 to 10-2. We find that, within this range of I, the friction coefficient μ of glass beads has no shear rate dependence. A particularly appealing observation comes from testing rice, where the attainment of critical state develops under much longer duration than in other materials. Initially during shear we find a value of μ similar to that found for glass beads, but with time this value decreases gradually towards the asymptotic critical state value. The reason, we believe, lies in the fact that rice grains are strongly elongated; hence the time to achieve the stable μ is primarily controlled by the time for particles to align themselves with respect to the shear walls. Furthermore, the initial packing conditions of samples also plays a role in the evolution of μ when the shear strain is small, but that impact will eventually be erased after sufficient shear strain.

Fitting cosmic microwave background data with cosmic strings and inflation.

Science.gov (United States)

Bevis, Neil; Hindmarsh, Mark; Kunz, Martin; Urrestilla, Jon

2008-01-18

We perform a multiparameter likelihood analysis to compare measurements of the cosmic microwave background (CMB) power spectra with predictions from models involving cosmic strings. Adding strings to the standard case of a primordial spectrum with power-law tilt ns, we find a 2sigma detection of strings: f10=0.11+/-0.05, where f10 is the fractional contribution made by strings in the temperature power spectrum (at l=10). CMB data give moderate preference to the model ns=1 with cosmic strings over the standard zero-strings model with variable tilt. When additional non-CMB data are incorporated, the two models become on a par. With variable ns and these extra data, we find that f10<0.11, which corresponds to Gmicro<0.7x10(-6) (where micro is the string tension and G is the gravitational constant).

The acceleration and propagation of energetic particles in turbulent cosmic plasmas

International Nuclear Information System (INIS)

Achterberg, A.

1981-01-01

This thesis concentrates on the acceleration and propagation of energetic particles in turbulent cosmic plasmas. The stochastic acceleration of relativistic electrons by long-wavelength weak magnetohydrodynamic turbulence is considered and a model is discussed that allows the determination of both the electron energy spectrum and the wavenumber spectrum of the magnetohydrodynamic turbulence in a consistent way. The question of second phase acceleration in large solar flares and the precise form of the force exerted on the background plasma when Alfven waves are generated by fast particles are considered. The energy balance in the shock wave acceleration, the propagation of energetic particles in a high β plasma (β>10 2 ) and sheared flow as a possible source of plasma turbulence for a magnetized plasma with field-aligned flow, are discussed. (Auth./C.F.)

Lithospheric shear velocity structure of South Island, New Zealand, from amphibious Rayleigh wave tomography

Science.gov (United States)

Ball, Justin S.; Sheehan, Anne F.; Stachnik, Joshua C.; Lin, Fan-Chi; Yeck, William L.; Collins, John A.

2016-05-01

We present a crust and mantle 3-D shear velocity model extending well offshore of New Zealand's South Island, imaging the lithosphere beneath the South Island as well as the Campbell and Challenger Plateaus. Our model is constructed via linearized inversion of both teleseismic (18-70 s period) and ambient noise-based (8-25 s period) Rayleigh wave dispersion measurements. We augment an array of 4 land-based and 29 ocean bottom instruments deployed off the South Island's east and west coasts in 2009-2010 by the Marine Observations of Anisotropy Near Aotearoa experiment with 28 land-based seismometers from New Zealand's permanent GeoNet array. Major features of our shear wave velocity (Vs) model include a low-velocity (Vs 50 km) beneath the central South Island exhibits strong spatial correlation with upper mantle earthquake hypocenters beneath the Alpine Fault. The ~400 km long low-velocity zone we image beneath eastern South Island and the inner Bounty Trough underlies Cenozoic volcanics and the locations of mantle-derived helium measurements, consistent with asthenospheric upwelling in the region.

Department of Cosmic Ray Physics: Overview

International Nuclear Information System (INIS)

Szabelski, J.

2001-01-01

Full text: The Department of Cosmic Ray Physics in Lodz is involved in basic research in the area of high-energy physics and cosmic ray physics related to: Experimental and phenomenological studies of Extensive Air Showers induced by cosmic ray particles. Studies of ultra-high energy (above 10 19 eV) cosmic rays: determination of energy and primary particle mass composition. Studies of asymptotic properties of hadronic interactions based on the analysis of cosmic ray propagation through the atmosphere. Studies of mass composition of cosmic rays in the energy range 10 15 -10 17 eV. Registration of cosmic ray intensity variation correlated with solar activity. Theoretical and experimental studies of Extensive Air Shower properties are performed mostly based on the results obtained by the Lodz Extensive Air Shower Array. We have noticed unexplainable delayed signals registered about 500-900 microseconds after the main EAS pulse. We prepared hardware for further experimental study of this effect. In September we have started registration of 5 GeV muon flux with the underground muon telescope. We registered 3 decreases of muon intensity correlated with Forbush decreases registered at lower energies. Variations of primary cosmic ray of energies up to about 100 GeV were responsible for our registrations. These set the upper limits for geometrical size of geomagnetic disturbances in interplanetary space. In construction and data interpretation of cosmic ray experiments, the Lodz group collaborates with many foreign institutes and laboratories: Forschungszentrum in Karlsruhe (Germany), College de France, Institute for Nuclear Studies of the Russian Academy of Sciences and Uppsala University (Sweden). We have organised (together with the Physics Department of the University of Lodz) the 17 th European Cosmic Ray Symposium (24-?8 July 2000) in which about 150 physicists participated (about 100 from abroad). (author)

Cosmic physics: the high energy frontier

International Nuclear Information System (INIS)

Stecker, F W

2003-01-01

Cosmic rays have been observed up to energies 10 8 times larger than those of the best particle accelerators. Studies of astrophysical particles (hadrons, neutrinos and photons) at their highest observed energies have implications for fundamental physics as well as astrophysics. Thus, the cosmic high energy frontier is the nexus to new particle physics. This overview discusses recent advances being made in the physics and astrophysics of cosmic rays and cosmic γ-rays at the highest observed energies as well as the related physics and astrophysics of very high energy cosmic neutrinos. These topics touch on questions of grand unification, violations of Lorentz invariance as well as Planck scale physics and quantum gravity. (topical review)

Experimental study of shear rate dependence in perpetually sheared granular matter

Directory of Open Access Journals (Sweden)

Liu Sophie Yang

2017-01-01

Full Text Available We study the shear behaviour of various granular materials by conducting novel perpetual simple shear experiments over four orders of magnitude of relatively low shear rates. The newly developed experimental apparatus employed is called “3D Stadium Shear Device” which is an extended version of the 2D Stadium Shear Device [1]. This device is able to provide a non-radial dependent perpetual shear flow and a nearly linear velocity profile between two oppositely moving shear walls. Using this device, we are able to test a large variety of granular materials. Here, we demonstrate the applicability of the device on glass beads (diameter 1 mm, 3 mm, and 14 mm and rice. We particularly focus on studying these materials at very low inertial number I ranging from 10−6 to 10−2. We find that, within this range of I, the friction coefficient μ of glass beads has no shear rate dependence. A particularly appealing observation comes from testing rice, where the attainment of critical state develops under much longer duration than in other materials. Initially during shear we find a value of μ similar to that found for glass beads, but with time this value decreases gradually towards the asymptotic critical state value. The reason, we believe, lies in the fact that rice grains are strongly elongated; hence the time to achieve the stable μ is primarily controlled by the time for particles to align themselves with respect to the shear walls. Furthermore, the initial packing conditions of samples also plays a role in the evolution of μ when the shear strain is small, but that impact will eventually be erased after sufficient shear strain.

Cosmic rays and global warming

Energy Technology Data Exchange (ETDEWEB)

Erlykin, A.D. [P.N. Lebedev Physical Institute, Moscow (Russian Federation); Sloan, T. [Lancaster University (United Kingdom); Wolfendale, A.W. [Durham University (United Kingdom)

2010-07-01

The possible effects of cosmic rays on clouds could contribute to global warming. The argument is that the observed increased solar activity during the last century caused a decrease in the ionization due to cosmic rays since the lower energy cosmic particles are deflected by the magnetic field created by the increasing solar wind. This would lead to a decrease in cloud cover allowing more heating of the earth by the sun. Meteorological data combined to solar activity observations and simulations show that any effect of solar activity on clouds and the climate is likely to be through irradiance rather than cosmic rays. Since solar irradiance transfers 8 orders of magnitude more energy to the atmosphere than cosmic rays it is more plausible that this can produce a real effect. The total contribution of variable solar activity to global warming is shown to be less than 14% of the total temperature rise. (A.C.)

Impact of Cosmic-Ray Transport on Galactic Winds

Science.gov (United States)

Farber, R.; Ruszkowski, M.; Yang, H.-Y. K.; Zweibel, E. G.

2018-04-01

The role of cosmic rays generated by supernovae and young stars has very recently begun to receive significant attention in studies of galaxy formation and evolution due to the realization that cosmic rays can efficiently accelerate galactic winds. Microscopic cosmic-ray transport processes are fundamental for determining the efficiency of cosmic-ray wind driving. Previous studies modeled cosmic-ray transport either via a constant diffusion coefficient or via streaming proportional to the Alfvén speed. However, in predominantly cold, neutral gas, cosmic rays can propagate faster than in the ionized medium, and the effective transport can be substantially larger; i.e., cosmic rays can decouple from the gas. We perform three-dimensional magnetohydrodynamical simulations of patches of galactic disks including the effects of cosmic rays. Our simulations include the decoupling of cosmic rays in the cold, neutral interstellar medium. We find that, compared to the ordinary diffusive cosmic-ray transport case, accounting for the decoupling leads to significantly different wind properties, such as the gas density and temperature, significantly broader spatial distribution of cosmic rays, and higher wind speed. These results have implications for X-ray, γ-ray, and radio emission, and for the magnetization and pollution of the circumgalactic medium by cosmic rays.

Cosmic Topology

Science.gov (United States)

Luminet, Jean-Pierre

2015-08-01

Cosmic Topology is the name given to the study of the overall shape of the universe, which involves both global topological features and more local geometrical properties such as curvature. Whether space is finite or infinite, simply-connected or multi-connected like a torus, smaller or greater than the portion of the universe that we can directly observe, are questions that refer to topology rather than curvature. A striking feature of some relativistic, multi-connected "small" universe models is to create multiples images of faraway cosmic sources. While the most recent cosmological data fit the simplest model of a zero-curvature, infinite space model, they are also consistent with compact topologies of the three homogeneous and isotropic geometries of constant curvature, such as, for instance, the spherical Poincaré Dodecahedral Space, the flat hypertorus or the hyperbolic Picard horn. After a "dark age" period, the field of Cosmic Topology has recently become one of the major concerns in cosmology, not only for theorists but also for observational astronomers, leaving open a number of unsolved issues.

Cosmic ray physics goes to school

CERN Multimedia

2002-01-01

With the help of a CERN physicist, German Schools bring the Largest Cosmic Ray Detector in Europe one step closer to reality   Eric Berthier and Robert Porret (CERN, ST/HM), Frej Torp and Christian Antfolk from the Polytechnics Arcada in Finland, and Karsten Eggert, physicist at CERN who initiated this project, during the installation of cosmic ray detectors in the Pays de Gex, at point 4. Niina Patrikainen and Frej Torp, Finnish students from Rovaniemi and Arcada Polytechnics, installing cosmic ray counters at the Fachhochschule in Duesseldorf. The science of cosmic ray detection is growing, literally. Cosmic rays, energetic particles from space, strike our planet all the time. They collide with the air molecules in our upper atmosphere and initiate large showers of elementary particles (mainly electrons, photons, hadrons and muons) which rain down upon the earth. The shower size and the particle density in the showers reflect the initial energy of the cosmic ray particle, a detail which makes d...

Cosmic rays and the interstellar medium

International Nuclear Information System (INIS)

Wolfendale, A.W.

1986-01-01

It is inevitable that there is a close connection between cosmic rays and the ISM insofar as the propagation of cosmic rays is conditioned by the magnetic field in the ISM and the cosmic rays interact with the gas (and photon fluxes) in this medium. This paper deals with both topics. Propagation effects manifest themselves as an anisotropy in arrival directions and a review is given of anisotropy measurements and their interpretation. The status of studies of cosmic ray interactions is examined whit particular reference to the information about the ISM itself which comes from observations of the flux of secondary γ-rays produced by cosmic ray interactions with gas, the situation regarding molecular as in the Inner Galaxy being of particular concern

Looking for Cosmic Neutrino Background

Directory of Open Access Journals (Sweden)

Chiaki eYanagisawa

2014-06-01

Full Text Available Since the discovery of neutrino oscillation in atmospheric neutrinos by the Super-Kamiokande experiment in 1998, study of neutrinos has been one of exciting fields in high-energy physics. All the mixing angles were measured. Quests for 1 measurements of the remaining parameters, the lightest neutrino mass, the CP violating phase(s, and the sign of mass splitting between the mass eigenstates m3 and m1, and 2 better measurements to determine whether the mixing angle theta23 is less than pi/4, are in progress in a well-controlled manner. Determining the nature of neutrinos, whether they are Dirac or Majorana particles is also in progress with continuous improvement. On the other hand, although the ideas of detecting cosmic neutrino background have been discussed since 1960s, there has not been a serious concerted effort to achieve this goal. One of the reasons is that it is extremely difficult to detect such low energy neutrinos from the Big Bang. While there has been tremendous accumulation of information on Cosmic Microwave Background since its discovery in 1965, there is no direct evidence for Cosmic Neutrino Background. The importance of detecting Cosmic Neutrino Background is that, although detailed studies of Big Bang Nucleosynthesis and Cosmic Microwave Background give information of the early Universe at ~a few minutes old and ~300 k years old, respectively, observation of Cosmic Neutrino Background allows us to study the early Universe at $sim$ 1 sec old. This article reviews progress made in the past 50 years on detection methods of Cosmic Neutrino Background.

Shear thinning and shear thickening of a confined suspension of vesicles

Science.gov (United States)

Nait Ouhra, A.; Farutin, A.; Aouane, O.; Ez-Zahraouy, H.; Benyoussef, A.; Misbah, C.

2018-01-01

Widely regarded as an interesting model system for studying flow properties of blood, vesicles are closed membranes of phospholipids that mimic the cytoplasmic membranes of red blood cells. In this study we analyze the rheology of a suspension of vesicles in a confined geometry: the suspension, bound by two planar rigid walls on each side, is subject to a shear flow. Flow properties are then analyzed as a function of shear rate γ ˙, the concentration of the suspension ϕ , and the viscosity contrast λ =ηin/ηout , where ηin and ηout are the fluid viscosities of the inner and outer fluids, respectively. We find that the apparent (or effective viscosity) of the suspension exhibits both shear thinning (decreasing viscosity with shear rate) or shear thickening (increasing viscosity with shear rate) in the same concentration range. The shear thinning or thickening behaviors appear as subtle phenomena, dependant on viscosity contrast λ . We provide physical arguments on the origins of these behaviors.

Muon Tomography for Geological Repositories.

Science.gov (United States)

Woodward, D.; Kudryavtsev, V.; Gluyas, J.; Clark, S. J.; Thompson, L. F.; Klinger, J.; Spooner, N. J.; Blackwell, T. B.; Pal, S.; Lincoln, D. L.; Paling, S. M.; Mitchell, C. N.; Benton, C.; Coleman, M. L.; Telfer, S.; Cole, A.; Nolan, S.; Chadwick, P.

2015-12-01

Cosmic-ray muons are subatomic particles produced in the upper atmosphere in collisions of primary cosmic rays with atoms in air. Due to their high penetrating power these muons can be used to image the content (primarily density) of matter they pass through. They have already been used to image the structure of pyramids, volcanoes and other objects. Their applications can be extended to investigating the structure of, and monitoring changes in geological formations and repositories, in particular deep subsurface sites with stored CO2. Current methods of monitoring subsurface CO2, such as repeat seismic surveys, are episodic and require highly skilled personnel to operate. Our simulations based on simplified models have previously shown that muon tomography could be used to continuously monitor CO2 injection and migration and complement existing technologies. Here we present a simulation of the monitoring of CO2 plume evolution in a geological reservoir using muon tomography. The stratigraphy in the vicinity of the reservoir is modelled using geological data, and a numerical fluid flow model is used to describe the time evolution of the CO2 plume. A planar detection region with a surface area of 1000 m2 is considered, at a vertical depth of 776 m below the seabed. We find that one year of constant CO2 injection leads to changes in the column density of about 1%, and that the CO2 plume is already resolvable with an exposure time of less than 50 days. The attached figure show a map of CO2 plume in angular coordinates as reconstructed from observed muons. In parallel with simulation efforts, a small prototype muon detector has been designed, built and tested in a deep subsurface laboratory. Initial calibrations of the detector have shown that it can reach the required angular resolution for muon detection. Stable operation in a small borehole within a few months has been demonstrated.

Fermat Potentials of Embedded Lensing, the Integrated Sachs-Wolfe Effect, and Weak-Lensing of CMB by Cosmic Voids

Science.gov (United States)

Chen, Bin; Kantowski, R.; Dai, X.

2014-01-01

We have developed an accurate gravitational lens theory for an inhomogeneity embedded in an otherwise homogeneous universe, which to the lowest order is applicable to any mass distribution. We derive the Fermat potential for a spherically symmetric lens embedded in a FLRW cosmology and use it to investigate the late-time integrated Sachs-Wolfe effect (ISW) caused by individual large scale inhomogeneities, in particular, cosmic voids. We present a simple analytical expression for the CMB temperature fluctuation across such a lens as the derivative of the lens Fermat potential. Our formalism is applicable to both linear and nonlinear density evolution scenarios, to arbitrarily large density contrasts, and to all open and closed background cosmologies. Our results are particularly useful for modeling ISW effects extracted through stacking large numbers of cosmic voids and clusters (that is, the aperture photometry method). For structures co-expanding with the background cosmology, i.e., for time-independent density contrasts, we find that the gravitational lensing time delay alone can produce fluctuations of the order of seen in recent observations by WMAP and Planck. We revisit the possibility of explaining the non-Gaussian cold spot on the south hemisphere via the Rees-Sciama effect of a large cosmic void using constraints obtained from the most recent void catalogs and our new void-lensing formalism, and compare it with other explanations such as a collapsing cosmic texture. We also study the remapping of primordial CMB anisotropies, the weak-lensing shear, and magnification caused by void lensing.

Cosmic strings and galaxy formation

Science.gov (United States)

Bertschinger, Edmund

1989-01-01

The cosmogonical model proposed by Zel'dovich and Vilenkin (1981), in which superconducting cosmic strings act as seeds for the origin of structure in the universe, is discussed, summarizing the results of recent theoretical investigations. Consideration is given to the formation of cosmic strings, the microscopic structure of strings, gravitational effects, cosmic string evolution, and the formation of galaxies and large-scale structure. Simulation results are presented in graphs, and several outstanding issues are listed and briefly characterized.

The cosmic spiderweb: equivalence of cosmic, architectural and origami tessellations

Science.gov (United States)

Neyrinck, Mark C.; Hidding, Johan; Konstantatou, Marina; van de Weygaert, Rien

2018-04-01

For over 20 years, the term `cosmic web' has guided our understanding of the large-scale arrangement of matter in the cosmos, accurately evoking the concept of a network of galaxies linked by filaments. But the physical correspondence between the cosmic web and structural engineering or textile `spiderwebs' is even deeper than previously known, and also extends to origami tessellations. Here, we explain that in a good structure-formation approximation known as the adhesion model, threads of the cosmic web form a spiderweb, i.e. can be strung up to be entirely in tension. The correspondence is exact if nodes sampling voids are included, and if structure is excluded within collapsed regions (walls, filaments and haloes), where dark-matter multistreaming and baryonic physics affect the structure. We also suggest how concepts arising from this link might be used to test cosmological models: for example, to test for large-scale anisotropy and rotational flows in the cosmos.

The cosmic spiderweb: equivalence of cosmic, architectural and origami tessellations.

Science.gov (United States)

Neyrinck, Mark C; Hidding, Johan; Konstantatou, Marina; van de Weygaert, Rien

2018-04-01

For over 20 years, the term 'cosmic web' has guided our understanding of the large-scale arrangement of matter in the cosmos, accurately evoking the concept of a network of galaxies linked by filaments. But the physical correspondence between the cosmic web and structural engineering or textile 'spiderwebs' is even deeper than previously known, and also extends to origami tessellations. Here, we explain that in a good structure-formation approximation known as the adhesion model, threads of the cosmic web form a spiderweb, i.e. can be strung up to be entirely in tension. The correspondence is exact if nodes sampling voids are included, and if structure is excluded within collapsed regions (walls, filaments and haloes), where dark-matter multistreaming and baryonic physics affect the structure. We also suggest how concepts arising from this link might be used to test cosmological models: for example, to test for large-scale anisotropy and rotational flows in the cosmos.

The cosmic spiderweb: equivalence of cosmic, architectural and origami tessellations

Science.gov (United States)

Hidding, Johan; Konstantatou, Marina; van de Weygaert, Rien

2018-01-01

For over 20 years, the term ‘cosmic web’ has guided our understanding of the large-scale arrangement of matter in the cosmos, accurately evoking the concept of a network of galaxies linked by filaments. But the physical correspondence between the cosmic web and structural engineering or textile ‘spiderwebs’ is even deeper than previously known, and also extends to origami tessellations. Here, we explain that in a good structure-formation approximation known as the adhesion model, threads of the cosmic web form a spiderweb, i.e. can be strung up to be entirely in tension. The correspondence is exact if nodes sampling voids are included, and if structure is excluded within collapsed regions (walls, filaments and haloes), where dark-matter multistreaming and baryonic physics affect the structure. We also suggest how concepts arising from this link might be used to test cosmological models: for example, to test for large-scale anisotropy and rotational flows in the cosmos. PMID:29765637

Baryonic effects in cosmic shear tomography: PCA parametrization and importance of extreme baryonic models

Energy Technology Data Exchange (ETDEWEB)

Mohammed, Irshad [Fermilab; Gnedin, Nickolay Y. [Fermilab

2017-07-07

Baryonic effects are amongst the most severe systematics to the tomographic analysis of weak lensing data which is the principal probe in many future generations of cosmological surveys like LSST, Euclid etc.. Modeling or parameterizing these effects is essential in order to extract valuable constraints on cosmological parameters. In a recent paper, Eifler et al. (2015) suggested a reduction technique for baryonic effects by conducting a principal component analysis (PCA) and removing the largest baryonic eigenmodes from the data. In this article, we conducted the investigation further and addressed two critical aspects. Firstly, we performed the analysis by separating the simulations into training and test sets, computing a minimal set of principle components from the training set and examining the fits on the test set. We found that using only four parameters, corresponding to the four largest eigenmodes of the training set, the test sets can be fitted thoroughly with an RMS $\\sim 0.0011$. Secondly, we explored the significance of outliers, the most exotic/extreme baryonic scenarios, in this method. We found that excluding the outliers from the training set results in a relatively bad fit and degraded the RMS by nearly a factor of 3. Therefore, for a direct employment of this method to the tomographic analysis of the weak lensing data, the principle components should be derived from a training set that comprises adequately exotic but reasonable models such that the reality is included inside the parameter domain sampled by the training set. The baryonic effects can be parameterized as the coefficients of these principle components and should be marginalized over the cosmological parameter space.

Dosimetry of environmental radiations (cosmic ray)

International Nuclear Information System (INIS)

Yamasaki, Keizo

1978-01-01

Cosmic ray is dominant as environmental radiation, though the experimental determination made on cosmic ray doses is few in Japan. The free air ionization intensity at sea level due to cosmic ray has been estimated in the Bay of Wakasa, Japan, at middle geomagnetic latitude (25 deg. N), in October 1977. The ionization chambers used were two air and one argon types. Where the responses to cosmic and terrestrial gamma rays were equal, the ionization intensity due to cosmic ray was obtained by subtracting the ionization intensity due to terrestrial gamma ray from the total ionization intensity. As the terrestrial gamma ray, (1) U-238 series, Th-232 series, and K-40 in seawater, (2) K-40 in the material of a wooden ship, and (3) Rn-222 and its daughter products in the atmosphere were considered. The result of free air ionization due to cosmic ray with the argon chamber was slightly smaller than those with the other two air chambers; however, both were in good agreement within standard errors. (JPN.)

Department of Cosmic Ray Physics; Overview

International Nuclear Information System (INIS)

Szabelski, J.

2004-01-01

Full text: Cosmic Rays are energetic particles from outside the Solar System. The energy spectrum (power law energy dependence) suggests a non-thermal origin of these particles. Most of the studies of Cosmic Rays address fundamental problems such as: - the nature of the physical and astrophysical processes responsible for the high energies of particles (up to about 10 20 eV/particle), - estimation of the astrophysical conditions at the acceleration sites and/or a search for sources of Cosmic Rays, - properties of high energy particle interactions at very high energies (nuclear interactions at energies exceeding energies available in the laboratories). Some Cosmic Ray studies might have practical (commercial) implications, e.g. - ''cosmic weather'' forecast - predictions of geomagnetic disturbances related to Solar activity changes (due to large Solar Flares / events of Coronal Mass Ejections); these are important for large electricity networks, gas pipes, radio-wave connections, space missions and satellite experiments. The Department of Cosmic Ray Physics in Lodz is involved in basic research in the high energy Cosmic Ray field. Energetic Cosmic Ray particles produce cascades of particles in the atmosphere, called Extensive Air Showers (EAS). Registering EAS and their properties is the main theme of experimental studies of very high energy Cosmic Rays. In the Lodz Department we run an Extensive Air Shower array where EAS are registered. We concentrate our experimental research on the explanation of particle detection delayed by hundreds of microseconds with respect to the main EAS signals. In the underground (I5 meters) laboratory we continuously register muon (5 GeV energy threshold) flux with the multidirectional telescope. We have observed several disturbances (Forbush Decreases) in muon counting rates. The interpretation of these events for ''cosmic weather'' and for Cosmic Ray transport models in the interplanetary plasma are on going in collaboration with

Department of Cosmic Ray Physics - Overview

International Nuclear Information System (INIS)

Szabelski, J.

2010-01-01

Full text: The 31 st International Cosmic Ray Conference (31.ICRC) was held in Lodz on 7-15 July 2009. The Conference was organized by the University of Lodz (Department of High Energy Astrophysics and Department of Astrophysics) and IPJ (Department of Cosmic Ray Physics). ICRCs are held every two years and are the largest forums to present and discuss the current status of Cosmic Ray studies. The Conference we co-organized gathered about 750 scientists (including about 50 from Poland). This was a remarkable event. The Department of Cosmic Ray Physics in Lodz is involved in basic research in the field of high energy Cosmic Rays. Cosmic Rays are energetic panicles from outside the Solar System. Most studies of Cosmic Rays address fundamental problems: - the nature of the physical and astrophysical processes responsible for the high energies of the particles. - experimental search for sources of Cosmic Rays, - studies of the astrophysical conditions at the acceleration sites, - properties of particle interactions at very high energies. Presentation of Cosmic Ray registration to high school students has become a popular way to introduce panicle physics detectors and elementary particle detection techniques to young people, in Lodz and Poznan we organize workshops on particle physics for high school students. This is part of the European activity: EPPOG Masterclass - Hands on CERN. Energetic Cosmic Ray particles produce cascades of panicles in the atmosphere, called Extensive Air Showers (EAS). Registering EASs and their properties is the main means of studying experimentally high energy Cosmic Rays: · The satellite experiment JEM-EUSO will observe EASs from the International Space Station. The main target is to find Cosmic Ray Sources for the highest energy Cosmic Rays. JEM-EUSO will collect a large number of events since it will observe a large area of the atmosphere. We are participating in the preparation of this mission. · The KASCADE-Grande addresses

A high time and spatial resolution MRPC designed for muon tomography

Science.gov (United States)

Shi, L.; Wang, Y.; Huang, X.; Wang, X.; Zhu, W.; Li, Y.; Cheng, J.

2014-12-01

A prototype of cosmic muon scattering tomography system has been set up in Tsinghua University in Beijing. Multi-gap Resistive Plate Chamber (MRPC) is used in the system to get the muon tracks. Compared with other detectors, MRPC can not only provide the track but also the Time of Flight (ToF) between two detectors which can estimate the energy of particles. To get a more accurate track and higher efficiency of the tomography system, a new type of high time and two-dimensional spatial resolution MRPC has been developed. A series of experiments have been done to measure the efficiency, time resolution and spatial resolution. The results show that the efficiency can reach 95% and its time resolution is around 65 ps. The cluster size is around 4 and the spatial resolution can reach 200 μ m.

MASKED AREAS IN SHEAR PEAK STATISTICS: A FORWARD MODELING APPROACH

International Nuclear Information System (INIS)

Bard, D.; Kratochvil, J. M.; Dawson, W.

2016-01-01

The statistics of shear peaks have been shown to provide valuable cosmological information beyond the power spectrum, and will be an important constraint of models of cosmology in forthcoming astronomical surveys. Surveys include masked areas due to bright stars, bad pixels etc., which must be accounted for in producing constraints on cosmology from shear maps. We advocate a forward-modeling approach, where the impacts of masking and other survey artifacts are accounted for in the theoretical prediction of cosmological parameters, rather than correcting survey data to remove them. We use masks based on the Deep Lens Survey, and explore the impact of up to 37% of the survey area being masked on LSST and DES-scale surveys. By reconstructing maps of aperture mass the masking effect is smoothed out, resulting in up to 14% smaller statistical uncertainties compared to simply reducing the survey area by the masked area. We show that, even in the presence of large survey masks, the bias in cosmological parameter estimation produced in the forward-modeling process is ≈1%, dominated by bias caused by limited simulation volume. We also explore how this potential bias scales with survey area and evaluate how much small survey areas are impacted by the differences in cosmological structure in the data and simulated volumes, due to cosmic variance

Muon tomography of the Soufrière of Guadeloupe (Lesser Antilles): Comparison with other geophysical imaging methods and assessment of volcanic risks

Science.gov (United States)

Gibert, D.; Lesparre, N.; Marteau, J.; Taisne, B.; Nicollin, F.; Coutant, O.

2011-12-01

Density tomography of rock with muons of cosmic origin measures the attenuation of the flux of particles crossing the object of interest to derive its opacity, i.e. the quantity of matter encountered by the particles along their trajectories. Recent progress in micro-electronics and particle detectors make field measurement possible and muon density tomography is gaining a growing interest (e.g. Tanaka et al., 2010; Gibert et al., 2010). We have constructed field telescopes based on the detectors of the OPERA experiment devoted to study neutrino oscillation (Lesparre et al., 2011a). Each telescope may be equipped with a variable number of detection matrices with 256 pixels. The spatial resolution is adaptable and is typically of about 20 meters (Lesparre et al., 2010). The telescopes are portable autonomous devices able to operate in harsh field conditions encountered on tropical volcanoes. The total power consumption is less than 40W, and an Ethernet link allows data downloading and remote control of the electronic devices and on-board computers. Larger high-resolution telescopes are under construction. The instruments have been successfully tested on the Etna and Soufrière of Guadeloupe volcanoes were a telescope is operating continuously since Summer 2010. Muon radiographies of the Soufrière lava dome reveal its very heterogeneous density structure produced by an intense hydrothermal circulation of acid fluids which alters its mechanical integrity leading to a high risk level of destabilisation. Small-size features are visible on the images and provide precious informations on the structure of the upper hydrothermal systems. Joined interpretation with other geophysical data available on the Soufrière - seismic tomography, electrical resistivity tomography, gravity data - is presented and discussed. Density muon tomography of the internal structure of volcanoes like the Soufrière brings important informations for the hazard evaluation an is particularly

Cosmic antimatter

International Nuclear Information System (INIS)

Tarle, G.; Swordy, S.

1998-01-01

In 1928 Paul Dirac forecasted the existence of antimatter and 4 years later Carl Anderson detected the first antiparticle: the positron in a cloud chamber while studying cosmic radiation. Antiprotons were more difficult to find but in 1955 physicists from Lawrence Berkeley Laboratory got some in a particle accelerator. In 1995 a team from the CERN synthesized atoms of anti-hydrogen by binding positrons to antiprotons in a particle accelerator. Astrophysicists have built more and more complex detectors to study cosmic rays. The detector HEAT (high energy antimatter telescope) has been designed to study positrons above the atmosphere. This detector has been launched for the first time in 1994 and has measured cosmic radiation for 32 hours at an altitude of 37000 meters. The results were challenging: whereas the number of low energy positrons detected agrees with the theory, the number of high energy positrons is too important. It suggests the existence of unknown sources of positrons somewhere in the universe. The massive particles that interact weakly (WIMP) could be such sources. This article draws the history of the quest for antimatter and its implications in cosmology, the detector HEAT is described. (A.C.)

Recent Advances and Field Trial Results Integrating Cosmic Ray Muon Tomography with Other Data Sources for Mineral Exploration

Science.gov (United States)

Schouten, D.

2015-12-01

CRM GeoTomography Technologies, Inc. is leading the way in applying muon tomography to discovery and definition of dense ore bodies for mineral exploration and resource estimation. We have successfully imaged volcanogenic massive sulfide (VMS) deposits at mines in North America using our suite of field-proven muon tracking detectors, and are at various stages of development for other applications. Recently we developed in-house inversion software that integrates data from assays, surface and borehole gravity, and underground muon flux measurements. We have found that the differing geophysical data sources provide complementary information and that dramatic improvements in inversion results are attained using various inversion performance metrics related to the excess tonnage of the mineral deposits, as well as their spatial extents and locations. This presentation will outline field tests of muon tomography performed by CRM Geotomography in some real world examples, and will demonstrate the effectiveness of joint muon tomography, assay and gravity inversion techniques in field tests (where data are available) and in simulations.

Primary cosmic ray flux

Energy Technology Data Exchange (ETDEWEB)

Stanev, Todor

2001-05-01

We discuss the primary cosmic ray flux from the point of view of particle interactions and production of atmospheric neutrinos. The overall normalization of the cosmic ray flux and its time variations and site dependence are major ingredients of the atmospheric neutrino predictions and the basis for the derivation of the neutrino oscillation parameters.

The composition and structure of volcanic rifted continental margins in the North Atlantic: Further insight from shear waves

Science.gov (United States)

Eccles, Jennifer D.; White, Robert S.; Christie, Philip A. F.

2011-07-01

Imaging challenges caused by highly attenuative flood basalt sequences have resulted in the understanding of volcanic rifted continental margins lagging behind that of non-volcanic rifted and convergent margins. Massive volcanism occurred during break-up at 70% of the passive margins bordering the Atlantic Ocean, the causes and dynamics of which are still debated. This paper shows results from traveltime tomography of compressional and converted shear wave arrivals recorded on 170 four-component ocean bottom seismometers along two North Atlantic continental margin profiles. This traveltime tomography was performed using two different approaches. The first, a flexible layer-based parameterisation, enables the quality control of traveltime picks and investigation of the crustal structure. The second, with a regularised grid-based parameterisation, requires correction of converted shear wave traveltimes to effective symmetric raypaths and allows exploration of the model space via Monte Carlo analyses. The velocity models indicate high lower-crustal velocities and sharp transitions in both velocity and Vp/Vs ratios across the continent-ocean transition. The velocities are consistent with established mixing trends between felsic continental crust and high magnesium mafic rock on both margins. Interpretation of the high quality seismic reflection profile on the Faroes margin confirms that this mixing is through crustal intrusion. Converted shear wave data also provide constraints on the sub-basalt lithology on the Faroes margin, which is interpreted as a pre-break-up Mesozoic to Paleocene sedimentary system intruded by sills.

Measurement of cosmic-ray muons with the Distributed Electronic Cosmic-ray Observatory, a network of smartphones

International Nuclear Information System (INIS)

Vandenbroucke, J.; Bravo, S.; Karn, P.; Meehan, M.; Plewa, M.; Schultz, D.; Tosi, D.; BenZvi, S.; Jensen, K.; Peacock, J.; Ruggles, T.; Santander, M.; Simons, A.L.

2016-01-01

Solid-state camera image sensors can be used to detect ionizing radiation in addition to optical photons. We describe the Distributed Electronic Cosmic-ray Observatory (DECO), an app and associated public database that enables a network of consumer devices to detect cosmic rays and other ionizing radiation. In addition to terrestrial background radiation, cosmic-ray muon candidate events are detected as long, straight tracks passing through multiple pixels. The distribution of track lengths can be related to the thickness of the active (depleted) region of the camera image sensor through the known angular distribution of muons at sea level. We use a sample of candidate muon events detected by DECO to measure the thickness of the depletion region of the camera image sensor in a particular consumer smartphone model, the HTC Wildfire S. The track length distribution is fit better by a cosmic-ray muon angular distribution than an isotropic distribution, demonstrating that DECO can detect and identify cosmic-ray muons despite a background of other particle detections. Using the cosmic-ray distribution, we measure the depletion thickness to be 26.3 ± 1.4 μm. With additional data, the same method can be applied to additional models of image sensor. Once measured, the thickness can be used to convert track length to incident polar angle on a per-event basis. Combined with a determination of the incident azimuthal angle directly from the track orientation in the sensor plane, this enables direction reconstruction of individual cosmic-ray events using a single consumer device. The results simultaneously validate the use of cell phone camera image sensors as cosmic-ray muon detectors and provide a measurement of a parameter of camera image sensor performance which is not otherwise publicly available

Cosmic Ray Physics with ACORDE at LHC

CERN Document Server

Pagliarone, C.

2008-01-01

The use of large underground high-energy physics experiments, for comic ray studies, have been used, in the past, at CERN, in order to measure, precisely, the inclusive cosmic ray flux in the energy range from 2x10^10 - 2x10^12 eV. ACORDE, ALICE Cosmic Rays DEtector, will act as Level 0 cosmic ray trigger and, together with other ALICE apparatus, will provide precise information on cosmic rays with primary energies around 10^15 - 10^17 eV. This paper reviews the main detector features, the present status, commissioning and integration with other apparatus. Finally, we discuss the ACORDE-ALICE cosmic ray physics program.

Cosmic ray physics with ACORDE at LHC

International Nuclear Information System (INIS)

Pagliarone, C; Fernandez-Tellez, A

2008-01-01

The use of large underground high-energy physics experiments, for comic ray studies, have been used, in the past, at CERN, in order to measure, precisely, the inclusive cosmic ray flux in the energy range from 2·10 10 to 2· 10 12 eV. ACORDE, ALICE Cosmic Rays DEtector, will act as Level 0 cosmic ray trigger and, together with other ALICE apparatus, will provide precise information on cosmic rays with primary energies around 10 15 to 10 17 eV. This paper reviews the main detector features, the present status, commissioning and integration with other apparatus. Finally, we discuss the ACORDE-ALICE cosmic ray physics program

Assessment of shear stress related parameters in the carotid bifurcation using mouse-specific FSI simulations.

Science.gov (United States)

De Wilde, David; Trachet, Bram; Debusschere, Nic; Iannaccone, Francesco; Swillens, Abigail; Degroote, Joris; Vierendeels, Jan; De Meyer, Guido R Y; Segers, Patrick

2016-07-26

The ApoE(-)(/)(-) mouse is a common small animal model to study atherosclerosis, an inflammatory disease of the large and medium sized arteries such as the carotid artery. It is generally accepted that the wall shear stress, induced by the blood flow, plays a key role in the onset of this disease. Wall shear stress, however, is difficult to derive from direct in vivo measurements, particularly in mice. In this study, we integrated in vivo imaging (micro-Computed Tomography-µCT and ultrasound) and fluid-structure interaction (FSI) modeling for the mouse-specific assessment of carotid hemodynamics and wall shear stress. Results were provided for 8 carotid bifurcations of 4 ApoE(-)(/)(-) mice. We demonstrated that accounting for the carotid elasticity leads to more realistic flow waveforms over the complete domain of the model due to volume buffering capacity in systole. The 8 simulated cases showed fairly consistent spatial distribution maps of time-averaged wall shear stress (TAWSS) and relative residence time (RRT). Zones with reduced TAWSS and elevated RRT, potential indicators of atherosclerosis-prone regions, were located mainly at the outer sinus of the external carotid artery. In contrast to human carotid hemodynamics, no flow recirculation could be observed in the carotid bifurcation region. Copyright © 2015 Elsevier Ltd. All rights reserved.

Measurements of Cosmic Magnetism with LOFAR and SKA

Directory of Open Access Journals (Sweden)

R. Beck

2007-06-01

Full Text Available The origin of magnetic fields in stars, galaxies and clusters is an open problem in astrophysics. The next-generation radio telescopes Low Frequency Array (LOFAR and Square Kilometre Array (SKA will revolutionize the study of cosmic magnetism. "The origin and evolution of cosmic magnetism" is a key science project for SKA. The planned all-sky survey of Faraday rotation measures (RM at 1.4 GHz will be used to model the structure and strength of the magnetic fields in the intergalactic medium, the interstellar medium of intervening galaxies, and in the Milky Way. A complementary survey of selected regions at around 200 MHz is planned as a key project for LOFAR. Spectro-polarimetry applied to the large number of spectral channels available for LOFAR and SKA will allow to separate RM components from distinct foreground and background regions and to perform 3-D Faraday tomography of the interstellar medium of the Milky Way and nearby galaxies. – Deep polarization mapping with LOFAR and SKA will open a new era also in the observation of synchrotron emission from magnetic fields. LOFAR's sensitivity will allow to map the structure of weak, extended magnetic fields in the halos of galaxies, in galaxy clusters, and possibly in the intergalactic medium. Polarization observations with SKA at higher frequencies (1–10 GHz will show the detailed magnetic field structure within the disks and central regions of galaxies, with much higher angular resolution than present-day radio telescopes.

Department of Cosmic Ray Physics; Overview

International Nuclear Information System (INIS)

Szabelski, J.

2003-01-01

Full text: Department of Cosmic Ray Physics in Lodz is involved in basic research in the area of high-energy physics and cosmic ray physics related to: - Experimental and phenomenological studies of Extensive Air Showers induced by cosmic ray particles. - Studies of ultra-high energy (above 10 19 eV) cosmic rays: determination of energy spectrum and mass composition of primary particles - Studies of asymptotic properties of hadronic interactions based on the analysis of cosmic ray propagation through the atmosphere. - Studies of mass composition of cosmic rays in the energy range 10 15 - 10 17 eV. - Registration of cosmic ray intensity variation correlated with solar activity. Theoretical and experimental studies of Extensive Air Shower properties are performed mostly basing on the results obtained by the Lodz Extensive Air Shower Array. We have noticed unexplainable delayed signals registered about 500-900 microseconds after the main EAS pulse. Neutron transport simulations were performed in collaboration with JINR in Dubna. We prepared hardware for further experimental study of this effect. Continuous registrations of 5 GeV muon flux with the underground muon telescope have been carried on over the year 2001. We have detected several changes of muon intensity correlated with Forbush decreases registered at lower energies. We have also started registrations of muon counting rate in the on-surface scintillation detectors. These measurements will be included to the analysis of the disturbed energy spectrum of primary cosmic rays and its dependence on interplanetary disturbances related to the solar activity. In construction and data interpretation of cosmic ray experiments the Lodz group collaborates with many foreign institutes and laboratories: Forschungszentrum in Karlsruhe (Germany), College de France, Institute for Nuclear Studies of the Russian Academy of Sciences, JINR in Dubna (Russia), Uppsala University (Sweden) and DESY (Germany). We have prepared a

Department of Cosmic Ray Physics: Overview

International Nuclear Information System (INIS)

Szabelski, J.

2002-01-01

Full text:The Department of Cosmic Ray Physics in Lodz is involved in basic research in the area of high-energy physics and cosmic ray physics related to: * Experimental and phenomenological studies of Extensive Air Showers induced by cosmic ray particles. * Studies of ultra-high energy (above 10 19 eV) cosmic rays: determination of energy spectrum and mass composition of primary particles * Studies of asymptotic properties of hadronic interactions based on the analysis of cosmic ray propagation through the atmosphere. * Studies of mass composition of cosmic rays in the energy range 10 15 -10 17 eV. * Registration of cosmic ray intensity variation correlated with solar activity. Theoretical and experimental studies of Extensive Air Shower properties are performed mostly based on the results obtained by the Lodz Extensive Air Shower Array. We have noticed unexplainable delayed signals registered about 500-900 microseconds after the main EAS pulse. We prepared hardware for further experimental study of this effect. Continuous registrations of 5 GeV muon flux with the underground muon telescope have been carried on during 2001. We detected several changes of muon intensity correlated with Forbush decreases registered at lower energies. We have also started registration of the muon counting rate in on-surface scintillation detectors. These measurements will be included to the analysis of the disturbed energy spectrum of primary cosmic rays and its dependence on interplanetary disturbances related to solar activity. In construction and data interpretation of cosmic ray experiments the Lodz group collaborates with many foreign institutes and laboratories: Forschungszentrum in Karlsruhe (Germany), College de France, Institute for Nuclear Studies of the Russian Academy of Sciences, Uppsala University (Sweden) and DESY (Germany). We have prepared a project of large air shower array for studies of cosmic rays up to 10 20 eV. Detectors would be placed on the roofs of high

Muon reconstruction performance using cosmic rays in CMS

CERN Document Server

Calderon, Alicia

2009-01-01

After the incident with the Large Hadron Collider (LHC) in September 2008, the Compact Muon Solenoid (CMS) collaboration invested a considerable effort in further refining the understanding of the detector using cosmic muon data. About 300 million cosmic events were recorded with the CMS detector fully operational and the central solenoid switched on at the nominal value of 3.8 Tesla. The resulting data set provides ample statistics to study in great detail the detector performance and allows to analyze properties of cosmic rays. We present recent results on detector performance from the cosmic muon analysis activities and compare cosmic data to dedicated cosmic Monte Carlo samples. These results demonstrate the readiness of the CMS detector to do physics analysis with muons, and the study of cosmic muon properties provides interesting links to astrophysics.

COSMIC-RAY TRANSPORT AND ANISOTROPIES

Energy Technology Data Exchange (ETDEWEB)

Biermann, Peter L. [MPI for Radioastronomy, Auf dem Huegel 69, D-53121 Bonn (Germany); Becker Tjus, Julia; Mandelartz, Matthias [Ruhr-Universitaet Bochum, Fakultaet fuer Physik and Astronomie, Theoretische Physik I, D-44780 Bochum (Germany); Seo, Eun-Suk [Department of Physics, University of Maryland, College Park, MD 20742 (United States)

2013-05-10

We show that the large-scale cosmic-ray anisotropy at {approx}10 TeV can be explained by a modified Compton-Getting effect in the magnetized flow field of old supernova remnants. Cosmic rays arrive isotropically to the flow field and are then carried along with the flow to produce a large-scale anisotropy in the arrival direction. This approach suggests an optimum energy scale for detecting the anisotropy. Two key assumptions are that propagation is based on turbulence following a Kolmogorov law and that cosmic-ray interactions are dominated by transport via cosmic-ray-excited magnetic irregularities through the stellar wind of an exploding star and its shock shell. A prediction is that the amplitude is smaller at lower energies due to incomplete sampling of the velocity field and also smaller at larger energies due to smearing.

Multi-spectra Cosmic Ray Flux Measurement

Science.gov (United States)

He, Xiaochun; Dayananda, Mathes

2010-02-01

The Earth's upper atmosphere is constantly bombarded by rain of charged particles known as primary cosmic rays. These primary cosmic rays will collide with the atmospheric molecules and create extensive secondary particles which shower downward to the surface of the Earth. In recent years, a few studies have been done regarding to the applications of the cosmic ray measurements and the correlations between the Earth's climate conditions and the cosmic ray fluxes [1,2,3]. Most of the particles, which reach to the surface of the Earth, are muons together with a small percentage of electrons, gammas, neutrons, etc. At Georgia State University, multiple cosmic ray particle detectors have been constructed to measure the fluxes and energy distributions of the secondary cosmic ray particles. In this presentation, we will briefly describe these prototype detectors and show the preliminary test results. Reference: [1] K.Borozdin, G.Hogan, C.Morris, W.Priedhorsky, A.Saunders, L.Shultz, M.Teasdale, Nature, Vol.422, 277 (2003). [2] L.V. Egorova, V. Ya Vovk, O.A. Troshichev, Journal of Atmospheric and Terrestrial Physics 62, 955-966 (2000). [3] Henrik Svensmark, Phy. Rev. Lett. 81, 5027 (1998). )

High energy physics in cosmic rays

Energy Technology Data Exchange (ETDEWEB)

Jones, Lawrence W. [University of Michigan, Ann Arbor, Michigan (United States)

2013-02-07

In the first half-century of cosmic ray physics, the primary research focus was on elementary particles; the positron, pi-mesons, mu-mesons, and hyperons were discovered in cosmic rays. Much of this research was carried out at mountain elevations; Pic du Midi in the Pyrenees, Mt. Chacaltaya in Bolivia, and Mt. Evans/Echo Lake in Colorado, among other sites. In the 1960s, claims of the observation of free quarks, and satellite measurements of a significant rise in p-p cross sections, plus the delay in initiating accelerator construction programs for energies above 100 GeV, motivated the Michigan-Wisconsin group to undertake a serious cosmic ray program at Echo Lake. Subsequently, with the succession of higher energy accelerators and colliders at CERN and Fermilab, cosmic ray research has increasingly focused on cosmology and astrophysics, although some groups continue to study cosmic ray particle interactions in emulsion chambers.

3D Tomography of a Mesa Using Cosmic Ray Muons Detected in an Underground Tunnel

Science.gov (United States)

Guardincerri, E.; Rowe, C. A.

2016-12-01

The LANL Mini Muon Tracker (MMT) is a muon tracking detector made of sealed aluminum drift tubes. The MMT was operated at four locations inside a tunnel under the Los Alamos town site mesa between November 2015 and February 2016 and it collected cosmic ray muons attenuated by the tunnel overburden. The data were analyzed and used to obtain a 3D tomographic image of the mesa and will be later combined with gravity data collected around the same location. We describe here the muon data taking and their analysis, and we show the resulting 3D image.

Cosmic rays, clouds and climate

Energy Technology Data Exchange (ETDEWEB)

Svensmark, Henrik [Danish Space Research Institute, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark)

2007-07-01

Changes in the intensity of galactic cosmic rays seems alter the Earth's cloudiness. A recent experiment has shown how electrons liberated by cosmic rays assist in making aerosols, the building blocks of cloud condensation nuclei, while anomalous climatic trends in Antarctica confirm the role of clouds in helping to drive climate change. Variations in the cosmic-ray influx due to solar magnetic activity account well for climatic fluctuations on decadal, centennial and millennial timescales. Over longer intervals, the changing galactic environment of the Solar System has had dramatic consequences, including Snowball Earth episodes.

High-energy cosmic-ray acceleration

CERN Document Server

Bustamante, M; de Paula, W; Duarte Chavez, J A; Gago, A M; Hakobyan, H; Jez, P; Monroy Montañez, J A; Ortiz Velasquez, A; Padilla Cabal, F; Pino Rozas, M; Rodriguez Patarroyo, D J; Romeo, G L; Saldaña-Salazar , U J; Velasquez, M; von Steinkirch, M

2010-01-01

We briefly review the basics of ultrahigh-energy cosmic-ray acceleration. The Hillas criterion is introduced as a geometrical criterion that must be fulfilled by potential acceleration sites, and energy losses are taken into account in order to obtain a more realistic scenario. The different available acceleration mechanisms are presented, with special emphasis on Fermi shock acceleration and its prediction of a power-law cosmic-ray energy spectrum. We conclude that first-order Fermi acceleration, though not entirely satisfactory, is the most promising mechanism for explaining the ultra-high-energy cosmic-ray flux.

Department of Cosmic Ray Physics - Overview

International Nuclear Information System (INIS)

Szabelski, J.

2008-01-01

Full text: The Department of Cosmic Ray Physics in Lodz is involved in basic research in the high energy Cosmic Ray field. Cosmic Rays are energetic particles from outside the Solar System. Most of the studies of Cosmic Rays address fundamental problems: · the nature of the physical and astrophysical processes responsible for high energies of particles · an estimation of the astrophysical conditions at the acceleration sites and/or search for sources of Cosmic Rays, · properties of high energy particle interactions at very high energies. Some Cosmic Ray studies might have practical (commercial) implications, e.g. · '' cosmic weather '' forecast - predictions of geomagnetic disturbances related to Solar activity changes (due to large Solar Flares / events of Coronal Mass Ejection); these are important for large electricity networks, gas pipes, radio-wave connections, space missions and satellite experiments. Presentation of Cosmic Ray registration to high school students becomes a popular way to introduce particle physics detectors and elementary particle detection techniques to young people. We organize in Lodz several workshops on particle physics for high school students. This is a part of European activity: EPPOG's Masterclass - Hands on CERN. Energetic Cosmic Ray particles produce cascades of particles in the atmosphere, called Extensive Air Showers (EAS). Registering EAS and their properties is the main way of experimental studies of very high energy Cosmic Rays. In Lodz Department we run Extensive Air Shower array where EAS are continuously being registered. We concentrate on the studies of detection of neutrons correlated with EAS and interpretation of this phenomenon. In 2004 we started realisation of the Roland Maze Project, the network of EAS detectors placed on the roofs of high schools in Lodz. We received funds from the City of Lodz budget to make a pilot project and equip 10 high schools, each with four 1m 2 detectors and GPS. The network is

ANALYSIS OF MAGNETOROTATIONAL INSTABILITY WITH THE EFFECT OF COSMIC-RAY DIFFUSION

Energy Technology Data Exchange (ETDEWEB)

Kuwabara, Takuhito [Computational Science and Engineering Division I, AdvanceSoft Corporation, 4-3, Kanda Surugadai, Chiyoda-ku, Tokyo 101-0062 (Japan); Ko, Chung-Ming, E-mail: kuwabrtk@gmail.com, E-mail: cmko@astro.ncu.edu.tw [Department of Physics, Institute of Astronomy and Center for Complex Systems, National Central University, Jhongli, Taiwan 320 (China)

2015-01-10

We present the results obtained from the linear stability analysis and 2.5 dimensional magnetohydrodynamic (MHD) simulations of magnetorotational instability (MRI), including the effects of cosmic rays (CRs). We took into account the CR diffusion along the magnetic field but neglected the cross-field-line diffusion. Two models are considered in this paper: the shearing box model and differentially rotating cylinder model. We studied how MRI is affected by the initial CR pressure (i.e., energy) distribution. In the shearing box model, the initial state is uniform distribution. Linear analysis shows that the growth rate of MRI does not depend on the value of the CR diffusion coefficient. In the differentially rotating cylinder model, the initial state is a constant angular momentum polytropic disk threaded by a weak uniform vertical magnetic field. Linear analysis shows that the growth rate of MRI becomes larger if the CR diffusion coefficient is larger. Both results are confirmed by MHD simulations. The MHD simulation results show that the outward movement of matter by the growth of MRI is not impeded by the CR pressure gradient, and the centrifugal force that acts on the concentrated matter becomes larger. Consequently, the growth rate of MRI is increased. On the other hand, if the initial CR pressure is uniform, then the growth rate of the MRI barely depends on the value of the CR diffusion coefficient.

Box Tomography: first application to the imaging of upper-mantle shear velocity and radial anisotropy structure beneath the North American continent

Science.gov (United States)

Clouzet, P.; Masson, Y.; Romanowicz, B.

2018-06-01

The EarthScope Transpotable Array (TA) deployment provides dense array coverage throughout the continental United States and with it, the opportunity for high-resolution 3-D seismic velocity imaging of the stable part of the North American (NA) upper mantle. Building upon our previous long-period waveform tomographic modeling, we present a higher resolution 3-D isotropic and radially anisotropic shear wave velocity model of the NA lithosphere and asthenosphere. The model is constructed using a combination of teleseismic and regional waveforms down to 40 s period and wavefield computations are performed using the spectral element method both for regional and teleseismic data. Our study is the first tomographic application of `Box Tomography', which allows us to include teleseismic events in our inversion, while computing the teleseismic wavefield only once, thus significantly reducing the numerical computational cost of several iterations of the regional inversion. We confirm the presence of high-velocity roots beneath the Archean part of the continent, reaching 200-250 km in some areas, however the thickness of these roots is not everywhere correlated to the crustal age of the corresponding cratonic province. In particular, the lithosphere is thick (˜250 km) in the western part of the Superior craton, while it is much thinner (˜150 km) in its eastern part. This may be related to a thermomechanical erosion of the cratonic root due to the passage of the NA plate over the Great Meteor hotspot during the opening of the Atlantic ocean 200-110 Ma. Below the lithosphere, an upper-mantle low-velocity zone (LVZ) is present everywhere under the NA continent, even under the thickest parts of the craton, although it is less developed there. The depth of the minimum in shear velocity has strong lateral variations, whereas the bottom of the LVZ is everywhere relatively flat around 270-300 km depth, with minor undulations of maximum 30 km that show upwarping under the thickest

Cosmic rays on earth

International Nuclear Information System (INIS)

Allkofer, O.C.; Grieder, P.K.F.

1984-01-01

A data collection is presented that covers cosmic rays on earth. Included are all relevant data on flux and intensity measurements, energy spectra, and related data of all primary and secondary components of the cosmic radiation at all levels in the atmosphere, at sea level and underground. In those cases where no useful experimental data have been available, theoretical predictions were substituted. (GSCH)

High-energy cosmic rays

CERN Document Server

Cronin, James Watson

1996-01-01

Recently two cosmic rays with energy in excess of 2 1020 eV have been recorded. These are some 108 times more energetic than the protons produced by accelerators on earth. There is no credible understanding of the mechanism of acceleration by known a Because of the short mean free path in the cosmic background radiation they must come from nearby distances on a cosmological scale (< 50 Mpc). Their magnetic rigidity suggests that they should point to their source. Lectures will cover the present available data on the highest energy cosmic rays, their detection, possible acceleration mechanisms, their propagation in the galaxy and in extra galactic space and design of new detectors where simulations of air show ers play an important role.

Empirical model for the Earth's cosmic ray shadow at 400 KM: prohibited cosmic ray access

International Nuclear Information System (INIS)

Humble, J.E.; Smart, D.F.; Shea, M.A.

1985-01-01

The possibility of constructing a unit sphere of access that describes the cosmic radiation allowed to an Earth-orbiting spacecraft is discussed. It is found that it is possible to model the occluded portion of the cosmic ray sphere of access as a circular projection with a diameter bounded by the satellite-Earth horizon. Maintaining tangency at the eastern edge of the spacecraft-Earth horizon, this optically occluded area is projected downward by an angle beta which is a function of the magnetic field inclination and cosmic ray arrival direction. This projected plane, corresponding to the forbidden area of cosmic ray access, is bounded by the spacecraft-Earth horizon in easterly directions, and is rotated around the vertical axis by an angle alpha from the eastern direction, where the angle alpha is a function of the offset dipole latitude of the spacecraft

Cosmic ray physics with ACORDE at LHC

Energy Technology Data Exchange (ETDEWEB)

Pagliarone, C [Universita degli Studi di Cassino and INFN Pisa, Largo B. Pontecorvo, 3 - Pisa (Italy); Fernandez-Tellez, A [Benemerita Universidad Autonoma de Puebla (BUAP), Puebla (Mexico)], E-mail: pagliarone@fnal.gov

2008-05-15

The use of large underground high-energy physics experiments, for comic ray studies, have been used, in the past, at CERN, in order to measure, precisely, the inclusive cosmic ray flux in the energy range from 2{center_dot}10{sup 10} to 2{center_dot} 10{sup 12} eV. ACORDE, ALICE Cosmic Rays DEtector, will act as Level 0 cosmic ray trigger and, together with other ALICE apparatus, will provide precise information on cosmic rays with primary energies around 10{sup 15} to 10{sup 17} eV. This paper reviews the main detector features, the present status, commissioning and integration with other apparatus. Finally, we discuss the ACORDE-ALICE cosmic ray physics program.

Cosmic ray investigations

International Nuclear Information System (INIS)

Zatsepin, Georgii T; Roganova, Tat'yana M

2009-01-01

The history of cosmic ray research at the Lebedev Institute beginning with the first work and continuing up to now is reviewed. The milestones and main avenues of research are outlined. Pioneering studies on the nuclear cascade process in extensive air showers, investigations of the Vavilov-Cherenkov radiation, and some work on the origin of cosmic rays are discussed. Recent data on ultrahigh-energy particle detection at the Pierre Auger Observatory and the High Resolution Fly's Eye (HiRes) experiments are presented. (conferences and symposia)

Cosmic Sum Rules

DEFF Research Database (Denmark)

T. Frandsen, Mads; Masina, Isabella; Sannino, Francesco

2011-01-01

We introduce new sum rules allowing to determine universal properties of the unknown component of the cosmic rays and show how it can be used to predict the positron fraction at energies not yet explored by current experiments and to constrain specific models.......We introduce new sum rules allowing to determine universal properties of the unknown component of the cosmic rays and show how it can be used to predict the positron fraction at energies not yet explored by current experiments and to constrain specific models....

Heterotic cosmic strings

International Nuclear Information System (INIS)

Becker, Katrin; Becker, Melanie; Krause, Axel

2006-01-01

We show that all three conditions for the cosmological relevance of heterotic cosmic strings, the right tension, stability and a production mechanism at the end of inflation, can be met in the strongly coupled M-theory regime. Whereas cosmic strings generated from weakly coupled heterotic strings have the well-known problems posed by Witten in 1985, we show that strings arising from M5-branes wrapped around 4-cycles (divisors) of a Calabi-Yau in heterotic M-theory compactifications solve these problems in an elegant fashion

Shear strength of non-shear reinforced concrete elements

DEFF Research Database (Denmark)

Hoang, Cao linh

1997-01-01

The paper deals with the shear strength of prestressed hollow-core slabs determined by the theory of plasticity. Two failure mechanisms are considered in order to derive the solutions.In the case of sliding failure in a diagonal crack, the shear strength is determined by means of the crack sliding...

Large angle cosmic microwave background fluctuations from cosmic strings with a cosmological constant

International Nuclear Information System (INIS)

Landriau, M.; Shellard, E.P.S.

2004-01-01

In this paper, we present results for large-angle cosmic microwave background anisotropies generated from high resolution simulations of cosmic string networks in a range of flat Friedmann-Robertson-Walker universes with a cosmological constant. Using an ensemble of all-sky maps, we compare with the Cosmic Background Explorer data to infer a normalization (or upper bound) on the string linear energy density μ. For a flat matter-dominated model (Ω M =1) we find Gμ/c 2 ≅0.7x10 -6 , which is lower than previous constraints probably because of the more accurate inclusion of string small-scale structure. For a cosmological constant within an observationally acceptable range, we find a relatively weak dependence with Gμ/c 2 less than 10% higher

Continuous shear - a method for studying material elements passing a stationary shear plane

DEFF Research Database (Denmark)

Lindegren, Maria; Wiwe, Birgitte; Wanheim, Tarras

2003-01-01

circumferential groove. Normally shear in metal forming processes is of another nature, namely where the material elements move through a stationary shear zone, often of small width. In this paper a method enabling the simulation of this situation is presented. A tool for continuous shear has beeen manufactured...... and tested with AlMgSil and copper. The sheared material has thereafter been tested n plane strain compression with different orientation concerning the angle between the shear plane and the compression direction....

Magnified Weak Lensing Cross Correlation Tomography

Energy Technology Data Exchange (ETDEWEB)

Ulmer, Melville P., Clowe, Douglas I.

2010-11-30

nights on 4-m class telescopes, which gives concrete evidence of strong community support for this project. The WLT technique is based on the dependence of the gravitational shear signal on the angular diameter distances between the observer, the lens, and the lensed galaxy to measure cosmological parameters. By taking the ratio of measured shears of galaxies with different redshifts around the same lens, one obtains a measurement of the ratios of the angular diameter distances involved. Making these observations over a large range of lenses and background galaxy redshifts will measure the history of the expansion rate of the universe. Because this is a purely geometric measurement, it is insensitive to any form of evolution of objects or the necessity to understand the physics in the early universe. Thus, WLT was identified by the Dark Energy Task Force as perhaps the best method to measure the evolution of DE. To date, however, the conjecture of the DETF has not been experimentally verified, but will be by the proposed project. The primary reason for the lack of tomography measurements is that one must have an exceptional data-set to attempt the measurement. One needs both extremely good seeing (or space observations) in order to minimize the point spread function smearing corrections on weak lensing shear measurements and deep, multi-color data, from B to z, to measure reliable photometric redshifts of the background galaxies being lensed (which are typically too faint to obtain spectroscopic redshifts). Because the entire process from multi-drizzling the HST images, and then creating shear maps, to gathering the necessary ground based observations, to generating photo-zs and then carrying out the tomography is a complicated task, until the creation of our team, nobody has taken the time to connect all the levels of expertise necessary to carry out this project based on HST archival data. Our data are being used in 2 Ph.D. theses. Kellen Murphy, at Ohio University, is

Cosmic radiation exposure to airline flight passenger

International Nuclear Information System (INIS)

Momose, Mitsuhiro

2000-01-01

At the high altitudes, airline flight passengers can be exposed to some levels of cosmic radiation. The purpose of this study was to quantify this radiation exposure. Cosmic radiation was measured during 5 flights using a personal dosimeter (PDM-102, Aloka). Cosmic radiation equivalent dose rates ranged from 0.7 to 1.43 microsieverts per hour, the average rate was 1.08. For the passenger who travels only occasionally, the cosmic radiation levels are well below occupational limits, and the risks are extremely small. (author)

Cosmic radiation exposure to airline flight passenger

Energy Technology Data Exchange (ETDEWEB)

Momose, Mitsuhiro [Shinshu Univ., Matsumoto, Nagano (Japan). School of Medicine

2000-08-01

At the high altitudes, airline flight passengers can be exposed to some levels of cosmic radiation. The purpose of this study was to quantify this radiation exposure. Cosmic radiation was measured during 5 flights using a personal dosimeter (PDM-102, Aloka). Cosmic radiation equivalent dose rates ranged from 0.7 to 1.43 microsieverts per hour, the average rate was 1.08. For the passenger who travels only occasionally, the cosmic radiation levels are well below occupational limits, and the risks are extremely small. (author)

Cosmic ray production curves below reworking zones

International Nuclear Information System (INIS)

Blanford, G.E.

1980-01-01

A method is presented for calculating cosmic ray production profiles below reworking zones. The method uses an input reworking depth determined from data such as signatures in the depth profile of ferromagnetic resonance intensity and input cosmic ray production profiles for an undisturbed surface. Reworking histories are simulated using Monte Carlo techniques, and depth profiles are used to determine cosmic ray exposure age limits with a specified probability. It is shown that the track density profiles predict cosmic ray exposure ages in lunar cores that are consistent with values determined by other methods. Results applied to neutron fluence and spallation rare gases eliminate the use of reworking depth as an adjustable parameter and give cosmic ray exposure ages that are compatible with each other

Department of Cosmic Ray Physics - Overview

International Nuclear Information System (INIS)

Szabelski, J.

2007-01-01

The Department of Cosmic Ray Physics in Lodz is involved in basic research in the high energy Cosmic Ray field. Cosmic Rays are energetic particles from outside the Solar System. The energy spectrum (power law energy dependence) suggests non-thermal origin of these particles. Most of the studies of Cosmic Rays address fundamental problems: · the nature of the physical and astrophysical processes responsible for high energies of particles (up to about 1020 eV/particle), · an estimation of the astrophysical conditions at the acceleration sites and/or search for sources of Cosmic Rays, · properties of high energy particle interactions at very high energies (nuclear interactions at energies exceeding energy available in the laboratories). Some Cosmic Ray studies might have practical (commercial) implications, e.g.: · '' cosmic weather '' forecast - predictions of geomagnetic disturbances related to Solar activity changes (due to large Solar Flares / events of Coronal Mass Ejection); these are important for large electricity networks, gas pipes, radio-wave connections, space missions and satellite experiments. Presentation of Cosmic Ray registration to high school students becomes a popular way to introduce particle physics detectors and elementary particle detection techniques to young people. We organize in Lodz several workshops on particle physics for high school students. This is a part of European activity: Masterclass - Hands on CERN. Energetic Cosmic Ray particles produce cascades of particles in the atmosphere, called Extensive Air Showers (EAS). Registering EAS and their properties is the main way of experimental studies of very high energy Cosmic Rays. In Lodz Department we run Extensive Air Shower array where EAS are continuously being registered. We concentrate on the studies of detection of neutrons correlated with EAS and interpretation of this phenomenon. Back in 2004 we started realisation of the Roland Maze Project, the network of EAS detectors

Proceedings of the 21. European Cosmic Ray Symposium

International Nuclear Information System (INIS)

Kiraly, P.; Kudela, K.; Wolfendale, A. W.

2008-09-01

Scientific symposium deals with problems of cosmic ray. The Symposium included the following sessions: (1): Relationship of cosmic rays to the environment; (2) Energetic particles and the magnetosphere of the Earth; (3) Energetic particles in the heliosphere; (4) Solar-terrestrial effects on different time scales; (5) Cosmic rays below the knee; (6) Cosmic rays above the knee (7) High energy interactions; (8) GeV and TeV gamma ray astronomy; (9) European projects related to cosmic rays; Future perspectives. Proceedings contains 122 papers dealing with the scope of INIS.

A Shifting Shield Provides Protection Against Cosmic Rays

Science.gov (United States)

Kohler, Susanna

2017-12-01

The Sun plays an important role in protecting us from cosmic rays, energetic particles that pelt us from outside our solar system. But can we predict when and how it will provide the most protection, and use this to minimize the damage to both pilotedand roboticspace missions?The Challenge of Cosmic RaysSpacecraft outside of Earths atmosphere and magnetic field are at risk of damage from cosmic rays. [ESA]Galactic cosmic rays are high-energy, charged particles that originate from astrophysical processes like supernovae or even distant active galactic nuclei outside of our solar system.One reason to care about the cosmic rays arriving near Earth is because these particles can provide a significant challenge for space missions traveling above Earths protective atmosphere and magnetic field. Since impacts from cosmic rays can damage human DNA, this risk poses a major barrier to plans for interplanetary travel by crewed spacecraft. And roboticmissions arent safe either: cosmic rays can flip bits, wreaking havoc on spacecraft electronics as well.The magnetic field carried by the solar wind provides a protective shield, deflecting galactic cosmic rays from our solar system. [Walt Feimer/NASA GSFCs Conceptual Image Lab]Shielded by the SunConveniently, we do have some broader protection against galactic cosmic rays: a built-in shield provided by the Sun. The interplanetary magnetic field, which is embedded in the solar wind, deflects low-energy cosmic rays from us at the outer reaches of our solar system, decreasing the flux of these cosmic rays that reach us at Earth.This shield, however, isnt stationary; instead, it moves and changes as the strength and direction of the solar wind moves and changes. This results in a much lower cosmic-ray flux at Earth when solar activity is high i.e., at the peak of the 11-year solar cycle than when solar activity is low. This visible change in local cosmic-ray flux with solar activity is known as solar modulation of the cosmic ray flux

Testing the weak gravity-cosmic censorship connection

Science.gov (United States)

Crisford, Toby; Horowitz, Gary T.; Santos, Jorge E.

2018-03-01

A surprising connection between the weak gravity conjecture and cosmic censorship has recently been proposed. In particular, it was argued that a promising class of counterexamples to cosmic censorship in four-dimensional Einstein-Maxwell-Λ theory would be removed if charged particles (with sufficient charge) were present. We test this idea and find that indeed if the weak gravity conjecture is true, one cannot violate cosmic censorship this way. Remarkably, the minimum value of charge required to preserve cosmic censorship appears to agree precisely with that proposed by the weak gravity conjecture.

Detection and Imaging of High-Z Materials with a Muon Tomography Station Using GEM Detectors

CERN Document Server

Gnanvo, K; Bittner, W; Costa, F; Grasso, L; Hohlmann, M; Locke, J B; Martoiu, S; Muller, H; Staib, M; Tarazona, A; Toledo, J

2010-01-01

Muon tomography based on the measurement of multiple scattering of atmospheric cosmic ray muons is a promising technique for detecting and imaging heavily shielded high-Z nuclear materials such as enriched uranium. This technique could complement standard radiation detection portals currently deployed at international borders and ports, which are not very sensitive to heavily shielded nuclear materials. We image small targets in 3D using $2\\times 2 \\times 2$ mm^3 voxels with a minimal muon tomography station prototype that tracks muons with Gas Electron Multiplier (GEM) detectors read out in 2D with x-y microstrips of 400 micron pitch. With preliminary electronics, the GEM detectors achieve a spatial resolution of 130 microns in both dimensions. With the next GEM-based prototype station we plan to probe an active volume of ~27 liters. We present first results on reading out all 1536 microstrips of a $30 \\times 30$ cm^2 GEM detector for the next muon tomography prototype with final frontend electronics and DAQ...

Cosmic rays at ultra high energies (Neutrinos.)

International Nuclear Information System (INIS)

Ahlers, M.; Ringwald, A.; Tu, H.

2005-06-01

Resonant photopion production with the cosmic microwave background predicts a suppression of extragalactic protons above the famous Greisen-Zatsepin-Kuzmin cutoff at about E GZK ∼ 5 x 10 10 GeV. Current cosmic ray data measured by the AGASA and HiRes Collaborations do not unambiguously confirm the GZK cutoff and leave a window for speculations about the origin and chemical composition of the highest energy cosmic rays. In this work we analyze the possibility of strongly interacting neutrino primaries and derive model-independent quantitative requirements on the neutrino-nucleon inelastic cross section for a viable explanation of the cosmic ray data. Search results on weakly interacting cosmic particles from the AGASA and RICE experiments are taken into account simultaneously. Using a flexible parameterization of the inelastic neutrino-nucleon cross section we find that a combined fit of the data does not favor the Standard Model neutrino-nucleon inelastic cross section, but requires, at 90% confidence level, a steep increase within one energy decade around E GZK by four orders of magnitude. We illustrate such an enhancement within some extensions of the Standard Model. The impact of new cosmic ray data or cosmic neutrino search results on this scenario, notably from the Pierre Auger Observatory soon, can be immediately evaluated within our approach. (orig.)

Separate structure of two branches of sheared slab ηi mode and effects of plasma rotation shear in weak magnetic shear region

International Nuclear Information System (INIS)

Jiquan Li; Kishimoto, Y.; Tuda, T.

2000-01-01

The separate structure of two branches of the sheared slab η i mode near the minimum-q magnetic surface is analysed and the effects of plasma rotation shears are considered in the weak magnetic shear region. Results show that the separation condition depends on the non-monotonous q profile and the deviation of rational surface from the minimum-q surface. Furthermore, it is found that the diamagnetic rotation shear may suppress the perturbation of the sheared slab η i mode at one side of the minimum-q surface, the poloidal rotation shear from the sheared E-vector x B-vector flow has a similar role to the slab mode structure when it possesses a direction same as the diamagnetic shear. A plausible interrelation between the separate structures of the two branches of the sheared slab mode and the discontinuity or gap of the radially global structure of the drift wave near the minimum-q surface observed in the toroidal particle simulation (Kishimoto Y et al 1998 Plasma Phys. Control. Fusion 40 A663) is discussed. It seems to support such a viewpoint: the double or/and global branches of the sheared slab η i mode near the minimum-q surface may become a bridge to connect the radially global structures of the drift wave at two sides of the minimum-q surface and the discontinuity may originate from the separate structures of these slab modes for a flatter q profile. (author)

The design and performance of a scintillating-fibre tracker for the cosmic-ray muon tomography of legacy nuclear waste containers

Science.gov (United States)

Clarkson, A.; Hamilton, D. J.; Hoek, M.; Ireland, D. G.; Johnstone, J. R.; Kaiser, R.; Keri, T.; Lumsden, S.; Mahon, D. F.; McKinnon, B.; Murray, M.; Nutbeam-Tuffs, S.; Shearer, C.; Staines, C.; Yang, G.; Zimmerman, C.

2014-05-01

Tomographic imaging techniques using the Coulomb scattering of cosmic-ray muons are increasingly being exploited for the non-destructive assay of shielded containers in a wide range of applications. One such application is the characterisation of legacy nuclear waste materials stored within industrial containers. The design, assembly and performance of a prototype muon tomography system developed for this purpose are detailed in this work. This muon tracker comprises four detection modules, each containing orthogonal layers of Saint-Gobain BCF-10 2 mm-pitch plastic scintillating fibres. Identification of the two struck fibres per module allows the reconstruction of a space point, and subsequently, the incoming and Coulomb-scattered muon trajectories. These allow the container content, with respect to the atomic number Z of the scattering material, to be determined through reconstruction of the scattering location and magnitude. On each detection layer, the light emitted by the fibre is detected by a single Hamamatsu H8500 MAPMT with two fibres coupled to each pixel via dedicated pairing schemes developed to ensure the identification of the struck fibre. The PMT signals are read out to standard charge-to-digital converters and interpreted via custom data acquisition and analysis software. The design and assembly of the detector system are detailed and presented alongside results from performance studies with data collected after construction. These results reveal high stability during extended collection periods with detection efficiencies in the region of 80% per layer. Minor misalignments of millimetre order have been identified and corrected in software. A first image reconstructed from a test configuration of materials has been obtained using software based on the Maximum Likelihood Expectation Maximisation algorithm. The results highlight the high spatial resolution provided by the detector system. Clear discrimination between the low, medium and high

Cosmic Rays in Intermittent Magnetic Fields

International Nuclear Information System (INIS)

Shukurov, Anvar; Seta, Amit; Bushby, Paul J.; Wood, Toby S.; Snodin, Andrew P.

2017-01-01

The propagation of cosmic rays in turbulent magnetic fields is a diffusive process driven by the scattering of the charged particles by random magnetic fluctuations. Such fields are usually highly intermittent, consisting of intense magnetic filaments and ribbons surrounded by weaker, unstructured fluctuations. Studies of cosmic-ray propagation have largely overlooked intermittency, instead adopting Gaussian random magnetic fields. Using test particle simulations, we calculate cosmic-ray diffusivity in intermittent, dynamo-generated magnetic fields. The results are compared with those obtained from non-intermittent magnetic fields having identical power spectra. The presence of magnetic intermittency significantly enhances cosmic-ray diffusion over a wide range of particle energies. We demonstrate that the results can be interpreted in terms of a correlated random walk.

Cosmic Rays in Intermittent Magnetic Fields

Energy Technology Data Exchange (ETDEWEB)

Shukurov, Anvar; Seta, Amit; Bushby, Paul J.; Wood, Toby S. [School of Mathematics and Statistics, Newcastle University, Newcastle Upon Tyne NE1 7RU (United Kingdom); Snodin, Andrew P., E-mail: a.seta1@ncl.ac.uk, E-mail: amitseta90@gmail.com [Department of Mathematics, Faculty of Applied Science, King Mongkut’s University of Technology North Bangkok, Bangkok 10800 (Thailand)

2017-04-10

The propagation of cosmic rays in turbulent magnetic fields is a diffusive process driven by the scattering of the charged particles by random magnetic fluctuations. Such fields are usually highly intermittent, consisting of intense magnetic filaments and ribbons surrounded by weaker, unstructured fluctuations. Studies of cosmic-ray propagation have largely overlooked intermittency, instead adopting Gaussian random magnetic fields. Using test particle simulations, we calculate cosmic-ray diffusivity in intermittent, dynamo-generated magnetic fields. The results are compared with those obtained from non-intermittent magnetic fields having identical power spectra. The presence of magnetic intermittency significantly enhances cosmic-ray diffusion over a wide range of particle energies. We demonstrate that the results can be interpreted in terms of a correlated random walk.

Semianalytic calculation of cosmic microwave background anisotropies from wiggly and superconducting cosmic strings

Science.gov (United States)

Rybak, I. Yu.; Avgoustidis, A.; Martins, C. J. A. P.

2017-11-01

We study how the presence of world-sheet currents affects the evolution of cosmic string networks, and their impact on predictions for the cosmic microwave background (CMB) anisotropies generated by these networks. We provide a general description of string networks with currents and explicitly investigate in detail two physically motivated examples: wiggly and superconducting cosmic string networks. By using a modified version of the CMBact code, we show quantitatively how the relevant network parameters in both of these cases influence the predicted CMB signal. Our analysis suggests that previous studies have overestimated the amplitude of the anisotropies for wiggly strings. For superconducting strings the amplitude of the anisotropies depends on parameters which presently are not well known—but which can be measured in future high-resolution numerical simulations.

The brittle-viscous-plastic evolution of shear bands in the South Armorican Shear Zone

Science.gov (United States)

Bukovská, Zita; Jeřábek, Petr; Morales, Luiz F. G.; Lexa, Ondrej; Milke, Ralf

2014-05-01

Shear bands are microscale shear zones that obliquely crosscut an existing anisotropy such as a foliation. The resulting S-C fabrics are characterized by angles lower than 45° and the C plane parallel to shear zone boundaries. The S-C fabrics typically occur in granitoids deformed at greenschist facies conditions in the vicinity of major shear zones. Despite their long recognition, mechanical reasons for localization of deformation into shear bands and their evolution is still poorly understood. In this work we focus on microscale characterization of the shear bands in the South Armorican Shear Zone, where the S-C fabrics were first recognized by Berthé et al. (1979). The initiation of shear bands in the right-lateral South Armorican Shear Zone is associated with the occurrence of microcracks crosscutting the recrystallized quartz aggregates that define the S fabric. In more advanced stages of shear band evolution, newly formed dominant K-feldspar, together with plagioclase, muscovite and chlorite occur in the microcracks, and the shear bands start to widen. K-feldspar replaces quartz by progressively bulging into the grain boundaries of recrystallized quartz grains, leading to disintegration of quartz aggregates and formation of fine-grained multiphase matrix mixture. The late stages of shear band development are marked by interconnection of fine-grained white mica into a band that crosscuts the original shear band matrix. In its extremity, the shear band widening may lead to the formation of ultramylonites. With the increasing proportion of shear band matrix from ~1% to ~12%, the angular relationship between S and C fabrics increases from ~30° to ~40°. The matrix phases within shear bands show differences in chemical composition related to distinct evolutionary stages of shear band formation. The chemical evolution is well documented in K-feldspar, where the albite component is highest in porphyroclasts within S fabric, lower in the newly formed grains within

Department of Cosmic Ray Physics - Overview

International Nuclear Information System (INIS)

Szabelski, J

2005-01-01

Full text: The Department of Cosmic Ray Physics in Lodz is involved in basic research in the high energy Cosmic Ray field. Cosmic Rays are energetic particles from outside the Solar System. The energy spectrum (power law energy dependence) suggests a non-thermal origin of these particles. Most studies of Cosmic Rays address fundamental problems: - the nature of the physical and astrophysical processes responsible for high energies of particles (up to about 10 20 eV/particle), - estimation of the astrophysical conditions at the acceleration sites and/or search for sources of Cosmic Rays, - properties of high energy particle interactions at very high energies (nuclear interactions at energies exceeding energy available in laboratories). - Some Cosmic Ray studies might have practical (commercial) implications, e.g. - ''cosmic weather'' forecast - predictions of geomagnetic disturbances related to Solar activity changes (due to large Solar Flares / events of Coronal Mass Ejection); these are important for large electricity networks, gas pipes, radio-wave connections, space missions and satellite experiments. Presentation of Cosmic Ray registration to high school students is a popular way to introduce particle physics detectors and elementary particle detection techniques to young people. Energetic Cosmic Ray particles produce cascades of particles in the atmosphere, called Extensive Air Showers (EAS). Registering the EAS and their properties is the main way of experimental studies of very high energy Cosmic Rays. In our Lodz Department we run an Extensive Air Shower array where EAS are continuously being registered. We concentrate on the studies of detection of neutrons correlated with EAS and interpretation of this phenomenon. In 2004 we started realisation of the Roland Maze Project, the network of EAS detectors placed on the roofs of high schools in Lodz. We received funds from the City of Lodz's budget to make a pilot project and equip 10 high schools, each with

Department of Cosmic Ray Physics - Overview

International Nuclear Information System (INIS)

Szabelski, J.

2009-01-01

Full text: The Department of Cosmic Ray Physics in Lodz is involved in basic research in the high-energy Cosmic Ray field. Cosmic Rays are energetic particles from outside the Solar System. Most of the studies of Cosmic Rays address fundamental problems: - the nature of the physical and astrophysical processes responsible for the high energies of the particles - an estimation of the astrophysical conditions at the acceleration sites and/or the search for sources of Cosmic Rays, - properties of high-energy particle interactions at very high energies. Some Cosmic Ray studies might have practical (commercial) implications, e.g. - '' cosmic weather '' forecasting - predictions of geomagnetic disturbances related to Solar activity changes (due to large Solar Flares/Coronal Mass Ejection events); these are important for large electricity networks, gas pipelines, radio-wave connections, space missions and satellite experiments. Presentation of Cosmic Ray registration to high school students has become a popular way to introduce particle physics detectors and elementary particle detection techniques to young people. We organize in Lodz and Poznan workshops on particle physics for high school students. This is a part of the European activity: EPPOG's Masterclass - Hands on CERN. Energetic Cosmic Ray particles produce cascades of particles in the atmosphere, called Extensive Air Showers (EAS). Registering EAS and their properties is the main way of experimentally study's very high energy Cosmic Rays. Locally in Lodz we concentrate on methodological studies of the detection of neutrons correlated with EAS and the interpretation of this phenomenon. We have also performed two series of neutron background measurements in the deep underground Gran Sasso Laboratory in Italy (within the ILIAS-TA Project). In 2004, we began the Roland Maze Project, a network of EAS detectors placed on the roofs of high schools in Lodz. The pilot project is to equip 10 high schools, each with four 1m

Cosmic-ray anisotropy studies with IceCube

Science.gov (United States)

McNally, Frank

2014-03-01

The IceCube neutrino observatory detects tens of billions of energetic muons per year produced by cosmic-ray interactions with the atmosphere. The size of this sample has allowed IceCube to observe a significant anisotropy in arrival direction for cosmic rays with median energies between 20 and 400 TeV. This anisotropy is characterized by a large scale structure of per-mille amplitude accompanied by structures with smaller amplitudes and with typical angular sizes between 10° and 20°. IceTop, the surface component of IceCube, has observed a similar anisotropy in the arrival direction distribution of cosmic rays, extending the study to PeV energies. The better energy resolution of IceTop allows for additional studies of the anisotropy, for example a comparison of the energy spectrum in regions of a cosmic-ray excess or deficit to the rest of the sky. We present an update on the cosmic-ray anisotropy observed with IceCube and IceTop and the results of first studies of the energy spectrum at locations of cosmic-ray excess or deficit.

Development of a large-area Multigap RPC with adequate spatial resolution for muon tomography

Science.gov (United States)

Wang, J.; Wang, Y.; Wang, X.; Zeng, M.; Xie, B.; Han, D.; Lyu, P.; Wang, F.; Li, Y.

2016-11-01

We study the performance of a large-area 2-D Multigap Resistive Plate Chamber (MRPC) designed for muon tomography with high spatial resolution. An efficiency up to 98% and a spatial resolution of around 270 μ m are obtained in cosmic ray and X-ray tests. The performance of the MRPC is also investigated for two working gases: standard gas and pure Freon. The result shows that the MRPC working in pure Freon can provide higher efficiency and better spatial resolution.

Integrated test plan for crosswell compressional and shear wave seismic tomography for site characterization at the VOC Arid Site

International Nuclear Information System (INIS)

Elbring, G.J.; Narbutovskih, S.M.

1994-01-01

This integrated test plan describes the demonstration of the crosswell acoustic tomography technique as part of the Volatile Organic Compounds-Arid Integrated Demonstration (VOC-Arid ID). The purpose of this demonstration is to image the subsurface seismic velocity structure and to relate the resulting velocity model to lithology and saturation. In fiscal year (FY) 1994 an initial fielding will test three different downhole sources at two different sites at the Hanford US Department of Energy facility to identify which sources will provide the energy required to propagate between existing steel-cased wells at these two sites. Once this has been established, a second fielding will perform a full compressional and shear wave tomographic survey at the most favorable site. Data reduction, analysis, and interpretation of this full data set will be completed by the end of this fiscal year. Data collection for a second survey will be completed by the end of the fiscal year, and data reduction for this data set will be completed in FY 1995. The specific need is detailed subsurface characterization with minimum intrusion. This technique also has applications for long term vadose zone monitoring for both Resource Conservation and Recovery Act (RCRA) waste storage facilities and for remediation monitoring. Images produced are continuous between boreholes. This is a significant improvement over the single point data derived solely from core information. Saturation changes, either naturally occurring (e.g., perched water tables) or remediation induced (e.g., water table mounding from injection wells or during inwell air sparging) could be imaged. These crosswell data allow optimal borehole placement for groundwater remediation, associated monitoring wells and possibly evaluation of the effective influence of a particular remediation technique

Shear Capacity of C-Shaped and L-Shaped Angle Shear Connectors.

Directory of Open Access Journals (Sweden)

Farzad Tahmasbi

Full Text Available This paper investigates the behaviour of C-shaped and L-shaped angle shear connectors embedded in solid concrete slabs. An effective finite element model is proposed to simulate the push out tests of these shear connectors that encompass nonlinear material behaviour, large displacement and damage plasticity. The finite element models are validated against test results. Parametric studies using this nonlinear model are performed to investigate the variations in concrete strength and connector dimensions. The finite element analyses also confirm the test results that increasing the length of shear connector increases their shear strength proportionately. It is observed that the maximum stress in L-shaped angle connectors takes place in the weld attachment to the beam, whereas in the C-shaped angle connectors, it is in the attached leg. The location of maximum concrete compressive damage is rendered in each case. Finally, a new equation for prediction of the shear capacity of C-shaped angle connectors is proposed.

Shear Capacity of C-Shaped and L-Shaped Angle Shear Connectors

Science.gov (United States)

Tahmasbi, Farzad; Maleki, Shervin; Shariati, Mahdi; Ramli Sulong, N. H.; Tahir, M. M.

2016-01-01

This paper investigates the behaviour of C-shaped and L-shaped angle shear connectors embedded in solid concrete slabs. An effective finite element model is proposed to simulate the push out tests of these shear connectors that encompass nonlinear material behaviour, large displacement and damage plasticity. The finite element models are validated against test results. Parametric studies using this nonlinear model are performed to investigate the variations in concrete strength and connector dimensions. The finite element analyses also confirm the test results that increasing the length of shear connector increases their shear strength proportionately. It is observed that the maximum stress in L-shaped angle connectors takes place in the weld attachment to the beam, whereas in the C-shaped angle connectors, it is in the attached leg. The location of maximum concrete compressive damage is rendered in each case. Finally, a new equation for prediction of the shear capacity of C-shaped angle connectors is proposed. PMID:27478894

A two-zone cosmic ray propagation model and its implication of the surviving fraction of radioactive cosmic ray isotopes

International Nuclear Information System (INIS)

Simon, M.; Scherzer, R.; Enge, W.

1977-01-01

In cosmic ray propagation calculations one can usually assume a homogeneous distribution of interstellar matter. The crucial astrophysical parameters in these models are: The path length distribution, the age of the cosmic ray particles and the interstellar matter density. These values are interrelated. The surviving fraction of radioactive cosmic ray isotopes is often used to determine a mean matter density of that region, where the cosmic ray particles may mainly reside. Using a Monte Carlo Propagation Program we calculated the change in the surviving fraction quantitatively assuming a region around the sources with higher matter density. (author)

Cosmic censorship and test particles

International Nuclear Information System (INIS)

Needham, T.

1980-01-01

In this paper one unambiguous prediction of cosmic censorship is put to the test, namely that it should be impossible to destroy a black hole (i.e. eliminate its horizon) by injecting test particles into it. Several authors have treated this problem and have not found their conclusions in contradiction with the prediction. Here we prove that if a general charged spinning particle (with parameters very much smaller than the respective hole parameters) is injected in an arbitrary manner into an extreme Kerr-Newman black hole, then cosmic censorship is upheld. As a by-product of the analysis a natural proof is given of the Christodoulou-Ruffini conditions on the injection of a spinless particle which yield a reversible black-hole transformation. Finally we consider the injection of particles with parameters that are not small compared with those of the hole, for which cosmic censorship is apparently violated. By assuming the validity of cosmic censorship we are led to a few conjectures concerning the extent of the particle's interaction with the hole while approaching it

Cosmic Strings and Their Induced Non-Gaussianities in the Cosmic Microwave Background

Directory of Open Access Journals (Sweden)

Christophe Ringeval

2010-01-01

small fraction of the CMB angular power spectrum, cosmic strings could actually be the main source of its non-Gaussianities. In this paper, after having reviewed the basic cosmological properties of a string network, we present the signatures Nambu-Goto cosmic strings would induce in various observables ranging from the one-point function of the temperature anisotropies to the bispectrum and trispectrum. It is shown that string imprints are significantly different than those expected from the primordial type of non-Gaussianity and could therefore be easily distinguished.

Department of Cosmic Ray Physics - Overview

International Nuclear Information System (INIS)

Szabelski, J.

2006-01-01

The Department of Cosmic Ray Physics in Lodz is involved in basic research in the high energy Cosmic Ray field. Cosmic Rays are energetic particles from outside the Solar System. The energy spectrum (power law energy dependence) suggests a non-thermal origin of these particles. Most of the studies of Cosmic Rays address fundamental problems: · The nature of the physical and astrophysical processes responsible for the high energies of the particles (up to about 1020 eV/particle), · An estimation of the astrophysical conditions at the acceleration sites and/or search for sources of Cosmic Rays, · properties of high energy particle interactions at very high energies (nuclear interactions at energies exceeding energy available in the laboratories). Some Cosmic Ray studies might have practical (commercial) implications, e.g. · 'cosmic weather' forecast - predictions of geomagnetic disturbances related to Solar activity changes (due to large Solar Flares / events of Coronal Mass Ejection); these are important for large electricity networks, gas pipes, radio-wave connections, space missions and satellite experiments. Presentation of Cosmic Ray registration to high school students becomes a popular way to introduce particle physics detectors and elementary particle detection techniques to young people. Energetic Cosmic Ray particles produce cascades of particles in the atmosphere, called Extensive Air Showers (EAS). Registering EAS and their properties is the main way of experimental studies of very high energy Cosmic Rays. In the Lodz Department we run the Extensive Air Shower array where EAS are being registered. We concentrate on the studies of detection of neutrons correlated with EAS and interpretation of this phenomenon. In 2004, we started realisation of the Roland Maze Project, the network of EAS detectors placed on roofs of high schools in Lodz. We received funds from the City of Lodz budget to make a pilot project and equip 10 high schools, each with four 1 m

Plasticity Approach to Shear Design

DEFF Research Database (Denmark)

Hoang, Cao Linh; Nielsen, Mogens Peter

1998-01-01

The paper presents some plastic models for shear design of reinforced concrete beams. Distinction is made between two shear failure modes, namely web crushing and crack sliding. The first mentioned mode is met in beams with large shear reinforcement degrees. The mode of crack sliding is met in non......-shear reinforced beams as well as in lightly shear reinforced beams. For such beams the shear strength is determined by the recently developed crack sliding model. This model is based upon the hypothesis that cracks can be transformed into yield lines, which have lower sliding resistance than yield lines formed...... in uncracked concrete. Good agree between theory and tests has been found.Keywords: dsign, plasticity, reinforced concrete, reinforcement, shear, web crushing....

Tracing the cosmic web

Science.gov (United States)

Libeskind, Noam I.; van de Weygaert, Rien; Cautun, Marius; Falck, Bridget; Tempel, Elmo; Abel, Tom; Alpaslan, Mehmet; Aragón-Calvo, Miguel A.; Forero-Romero, Jaime E.; Gonzalez, Roberto; Gottlöber, Stefan; Hahn, Oliver; Hellwing, Wojciech A.; Hoffman, Yehuda; Jones, Bernard J. T.; Kitaura, Francisco; Knebe, Alexander; Manti, Serena; Neyrinck, Mark; Nuza, Sebastián E.; Padilla, Nelson; Platen, Erwin; Ramachandra, Nesar; Robotham, Aaron; Saar, Enn; Shandarin, Sergei; Steinmetz, Matthias; Stoica, Radu S.; Sousbie, Thierry; Yepes, Gustavo

2018-01-01

The cosmic web is one of the most striking features of the distribution of galaxies and dark matter on the largest scales in the Universe. It is composed of dense regions packed full of galaxies, long filamentary bridges, flattened sheets and vast low-density voids. The study of the cosmic web has focused primarily on the identification of such features, and on understanding the environmental effects on galaxy formation and halo assembly. As such, a variety of different methods have been devised to classify the cosmic web - depending on the data at hand, be it numerical simulations, large sky surveys or other. In this paper, we bring 12 of these methods together and apply them to the same data set in order to understand how they compare. In general, these cosmic-web classifiers have been designed with different cosmological goals in mind, and to study different questions. Therefore, one would not a priori expect agreement between different techniques; however, many of these methods do converge on the identification of specific features. In this paper, we study the agreements and disparities of the different methods. For example, each method finds that knots inhabit higher density regions than filaments, etc. and that voids have the lowest densities. For a given web environment, we find a substantial overlap in the density range assigned by each web classification scheme. We also compare classifications on a halo-by-halo basis; for example, we find that 9 of 12 methods classify around a third of group-mass haloes (i.e. Mhalo ∼ 1013.5 h-1 M⊙) as being in filaments. Lastly, so that any future cosmic-web classification scheme can be compared to the 12 methods used here, we have made all the data used in this paper public.

3-D Upper-Mantle Shear Velocity Model Beneath the Contiguous United States Based on Broadband Surface Wave from Ambient Seismic Noise

Science.gov (United States)

Xie, Jun; Chu, Risheng; Yang, Yingjie

2018-05-01

Ambient noise seismic tomography has been widely used to study crustal and upper-mantle shear velocity structures. Most studies, however, concentrate on short period (structure on a continental scale. We use broadband Rayleigh wave phase velocities to obtain a 3-D V S structures beneath the contiguous United States at period band of 10-150 s. During the inversion, 1-D shear wave velocity profile is parameterized using B-spline at each grid point and is inverted with nonlinear Markov Chain Monte Carlo method. Then, a 3-D shear velocity model is constructed by assembling all the 1-D shear velocity profiles. Our model is overall consistent with existing models which are based on multiple datasets or data from earthquakes. Our model along with the other post-USArray models reveal lithosphere structures in the upper mantle, which are consistent with the geological tectonic background (e.g., the craton root and regional upwelling provinces). The model has comparable resolution on lithosphere structures compared with many published results and can be used for future detailed regional or continental studies and analysis.

Shear-induced Bubble Coalescence in Rhyolitic Melts with Low Vesicularity

Science.gov (United States)

Okumura, S.; Nakamura, M.; Tsuchiyama, A.

2006-12-01

Development of bubble structure during magma ascent controls the dynamics of volcanic eruption, because the bubble structure influences the magma rheology and permeability, and hence magma degassing. In the flowing magmas, the bubble structure is expected to be changed by shear, as pointed out by some previous studies based on geological observations. However, the development of bubble structure has been experimentally studied only in the isostatic magmas. We have experimentally demonstrated for the first time, the shear-induced development of number density, size and shape of bubbles in a rhyolitic melt. The deformation experiments were performed by using an externally heated, piston-cylinder type apparatus with a rotational piston. At 975°C, natural obsidian (initial water content of 0.5 wt%) having cylindrical shape (ca. 4.7 mm in diameter and 5 mm in length) was vesiculated in the graphite container (ca. 5 and 9 mm in the inner and the outer diameters, respectively, and 5 mm in length), and the vesiculated samples were twisted at various rotational speeds up to 1 rpm. The number density, size and shape of bubbles in the quenched samples were then measured by using the X-ray computed tomography. The size distribution of bubbles shows that the number of larger bubbles increases with the rotational speed and at the outer zone of the samples at which the shear rate is high. In the high shear rate zone, the magnitude of bubble deformation is large. The 3D images of large bubbles clearly indicate that they were formed by coalescence. These results indicate that the degree of bubble coalescence is enhanced with the shear rate. The experimental results also demonstrated that the coalescence of bubbles occur even at low vesicularity (ca. 20 vol.%). Because the shear rate induced in this study (in the order of 0.01 1/s) seems to be produced for magmas ascending in a volcanic conduit, we propose the possibility that the vesiculated magmas undergo bubble coalescence at a

Turbulence suppression by E x B shear in JET optimized shear pulses

International Nuclear Information System (INIS)

Beer, M.A.; Budny, R.V.; Challis, C.D.; Conway, G.

2000-01-01

The authors calculate microinstability growth rates in JET optimized shear plasmas with a comprehensive gyrofluid model, including sheared E x B flows, trapped electrons, and all dominant ion species in realistic magnetic geometry. They find good correlation between E x B shear suppression of microinstabilities and both the formation and collapse of the internal transport barrier

Shear Strains, Strain Rates and Temperature Changes in Adiabatic Shear Bands

Science.gov (United States)

1980-05-01

X14A. It has been found that when bainitic and martensitic steels are sheared adiabatically, a layer of material within ths shear zone is altezed and...Sooiety for Metals, Metals Park, Ohio, 1978, pp. 148-0. 21 TABLE II SOLID-STATE TRANSFORMATIONS IN BAINITIC STEEL TRANSFORMATION TRANSFORMATION...shear, thermoplastic, plasticity, plastic deformation, armor, steel IL AnSRACT ( -=nba asoa.tm a naeoesM iN faity by bleak n bet/2972 Experiments

Angular correlation of cosmic neutrinos with ultrahigh-energy cosmic rays and implications for their sources

Energy Technology Data Exchange (ETDEWEB)

Moharana, Reetanjali; Razzaque, Soebur, E-mail: reetanjalim@uj.ac.za, E-mail: srazzaque@uj.ac.za [Department of Physics, University of Johannesburg, P.O. Box 524, Auckland Park 2006 (South Africa)

2015-08-01

Cosmic neutrino events detected by the IceCube Neutrino Observatory with energy 0∼> 3 TeV have poor angular resolutions to reveal their origin. Ultrahigh-energy cosmic rays (UHECRs), with better angular resolutions at 0>6 EeV energies, can be used to check if the same astrophysical sources are responsible for producing both neutrinos and UHECRs. We test this hypothesis, with statistical methods which emphasize invariant quantities, by using data from the Pierre Auger Observatory, Telescope Array and past cosmic-ray experiments. We find that the arrival directions of the cosmic neutrinos are correlated with 0≥ 10 EeV UHECR arrival directions at confidence level ≈ 90%. The strength of the correlation decreases with decreasing UHECR energy and no correlation exists at energy 0∼ 6 EeV . A search in astrophysical databases within 3{sup o} of the arrival directions of UHECRs with energy 0≥ 10 EeV, that are correlated with the IceCube cosmic neutrinos, resulted in 18 sources from the Swift-BAT X-ray catalog with redshift z≤ 0.06. We also found 3 objects in the Kühr catalog of radio sources using the same criteria. The sources are dominantly Seyfert galaxies with Cygnus A being the most prominent member. We calculate the required neutrino and UHECR fluxes to produce the observed correlated events, and estimate the corresponding neutrino luminosity (25 TeV–2.2 PeV) and cosmic-ray luminosity (500 TeV–180 EeV), assuming the sources are the ones we found in the Swift-BAT and Kühr catalogs. We compare these luminosities with the X-ray luminosity of the corresponding sources and discuss possibilities of accelerating protons to 0∼> 10 EeV and produce neutrinos in these sources.

Cosmic ray modulation

Science.gov (United States)

Agarwal Mishra, Rekha; Mishra, Rajesh Kumar

2016-07-01

Propagation of cosmic rays to and inside the heliosphere, encounter an outward moving solar wind with cyclic magnetic field fluctuation and turbulence, causing convection and diffusion in the heliosphere. Cosmic ray counts from the ground ground-based neutron monitors at different cut of rigidity show intensity changes, which are anti-correlated with sunspot numbers. They also lose energy as they propagate towards the Earth and experience various types of modulations due to different solar activity indices. In this work, we study the first three harmonics of cosmic ray intensity on geo-magnetically quiet days over the period 1965-2014 for Beijing, Moscow and Tokyo neutron monitoring stations located at different cut off rigidity. The amplitude of first harmonic remains high for low cutoff rigidity as compared to high cutoff rigidity on quiet days. The diurnal amplitude significantly decreases during solar activity minimum years. The diurnal time of maximum significantly shifts to an earlier time as compared to the corotational direction having different cutoff rigidities. The time of maximum for first harmonic significantly shifts towards later hours and for second harmonic it shifts towards earlier hours at low cutoff rigidity station as compared to the high cut off rigidity station on quiet days. The amplitude of second/third harmonics shows a good positive correlation with solar wind velocity, while the others (i.e. amplitude and phase) have no significant correlation on quiet days. The amplitude and direction of the anisotropy on quiet days does not show any significant dependence on high-speed solar wind streams for these neutron monitoring stations of different cutoff rigidity threshold. Keywords: cosmic ray, cut off rigidity, quiet days, harmonics, amplitude, phase.

Upper Mantle Shear Wave Structure Beneath North America From Multi-mode Surface Wave Tomography

Science.gov (United States)

Yoshizawa, K.; Ekström, G.

2008-12-01

The upper mantle structure beneath the North American continent has been investigated from measurements of multi-mode phase speeds of Love and Rayleigh waves. To estimate fundamental-mode and higher-mode phase speeds of surface waves from a single seismogram at regional distances, we have employed a method of nonlinear waveform fitting based on a direct model-parameter search using the neighbourhood algorithm (Yoshizawa & Kennett, 2002). The method of the waveform analysis has been fully automated by employing empirical quantitative measures for evaluating the accuracy/reliability of estimated multi-mode phase dispersion curves, and thus it is helpful in processing the dramatically increasing numbers of seismic data from the latest regional networks such as USArray. As a first step toward modeling the regional anisotropic shear-wave velocity structure of the North American upper mantle with extended vertical resolution, we have applied the method to long-period three-component records of seismic stations in North America, which mostly comprise the GSN and US regional networks as well as the permanent and transportable USArray stations distributed by the IRIS DMC. Preliminary multi-mode phase-speed models show large-scale patterns of isotropic heterogeneity, such as a strong velocity contrast between the western and central/eastern United States, which are consistent with the recent global and regional models (e.g., Marone, et al. 2007; Nettles & Dziewonski, 2008). We will also discuss radial anisotropy of shear wave speed beneath North America from multi-mode dispersion measurements of Love and Rayleigh waves.

KiDS-450 + 2dFLenS: Cosmological parameter constraints from weak gravitational lensing tomography and overlapping redshift-space galaxy clustering

Science.gov (United States)

Joudaki, Shahab; Blake, Chris; Johnson, Andrew; Amon, Alexandra; Asgari, Marika; Choi, Ami; Erben, Thomas; Glazebrook, Karl; Harnois-Déraps, Joachim; Heymans, Catherine; Hildebrandt, Hendrik; Hoekstra, Henk; Klaes, Dominik; Kuijken, Konrad; Lidman, Chris; Mead, Alexander; Miller, Lance; Parkinson, David; Poole, Gregory B.; Schneider, Peter; Viola, Massimo; Wolf, Christian

2018-03-01

We perform a combined analysis of cosmic shear tomography, galaxy-galaxy lensing tomography, and redshift-space multipole power spectra (monopole and quadrupole) using 450 deg2 of imaging data by the Kilo Degree Survey (KiDS-450) overlapping with two spectroscopic surveys: the 2-degree Field Lensing Survey (2dFLenS) and the Baryon Oscillation Spectroscopic Survey (BOSS). We restrict the galaxy-galaxy lensing and multipole power spectrum measurements to the overlapping regions with KiDS, and self-consistently compute the full covariance between the different observables using a large suite of N-body simulations. We methodically analyse different combinations of the observables, finding that the galaxy-galaxy lensing measurements are particularly useful in improving the constraint on the intrinsic alignment amplitude, while the multipole power spectra are useful in tightening the constraints along the lensing degeneracy direction. The fully combined constraint on S_8 ≡ σ _8 √{Ω _m/0.3}=0.742± 0.035, which is an improvement by 20 per cent compared to KiDS alone, corresponds to a 2.6σ discordance with Planck, and is not significantly affected by fitting to a more conservative set of scales. Given the tightening of the parameter space, we are unable to resolve the discordance with an extended cosmology that is simultaneously favoured in a model selection sense, including the sum of neutrino masses, curvature, evolving dark energy and modified gravity. The complementarity of our observables allows for constraints on modified gravity degrees of freedom that are not simultaneously bounded with either probe alone, and up to a factor of three improvement in the S8 constraint in the extended cosmology compared to KiDS alone.

Cosmic logic: a computational model

International Nuclear Information System (INIS)

Vanchurin, Vitaly

2016-01-01

We initiate a formal study of logical inferences in context of the measure problem in cosmology or what we call cosmic logic. We describe a simple computational model of cosmic logic suitable for analysis of, for example, discretized cosmological systems. The construction is based on a particular model of computation, developed by Alan Turing, with cosmic observers (CO), cosmic measures (CM) and cosmic symmetries (CS) described by Turing machines. CO machines always start with a blank tape and CM machines take CO's Turing number (also known as description number or Gödel number) as input and output the corresponding probability. Similarly, CS machines take CO's Turing number as input, but output either one if the CO machines are in the same equivalence class or zero otherwise. We argue that CS machines are more fundamental than CM machines and, thus, should be used as building blocks in constructing CM machines. We prove the non-computability of a CS machine which discriminates between two classes of CO machines: mortal that halts in finite time and immortal that runs forever. In context of eternal inflation this result implies that it is impossible to construct CM machines to compute probabilities on the set of all CO machines using cut-off prescriptions. The cut-off measures can still be used if the set is reduced to include only machines which halt after a finite and predetermined number of steps

The intergalactic propagation of ultrahigh energy cosmic ray nuclei

Energy Technology Data Exchange (ETDEWEB)

Hooper, Dan; /Fermilab; Sarkar, Subir; /Oxford U., Theor. Phys.; Taylor, Andrew M.; /Oxford U.

2006-08-01

We investigate the propagation of ultra-high energy cosmic ray nuclei (A = 1-56) from cosmologically distant sources through the cosmic radiation backgrounds. Various models for the injected composition and spectrum and of the cosmic infrared background are studied using updated photodisintegration cross-sections. The observational data on the spectrum and the composition of ultra-high energy cosmic rays are jointly consistent with a model where all of the injected primary cosmic rays are iron nuclei (or a mixture of heavy and light nuclei).

Imaging shear stress distribution and evaluating the stress concentration factor of the human eye

Science.gov (United States)

Joseph Antony, S.

2015-03-01

Healthy eyes are vital for a better quality of human life. Historically, for man-made materials, scientists and engineers use stress concentration factors to characterise the effects of structural non-homogeneities on their mechanical strength. However, such information is scarce for the human eye. Here we present the shear stress distribution profiles of a healthy human cornea surface in vivo using photo-stress analysis tomography, which is a non-intrusive and non-X-ray based method. The corneal birefringent retardation measured here is comparable to that of previous studies. Using this, we derive eye stress concentration factors and the directional alignment of major principal stress on the surface of the cornea. Similar to thermometers being used for monitoring the general health in humans, this report provides a foundation to characterise the shear stress carrying capacity of the cornea, and a potential bench mark for validating theoretical modelling of stresses in the human eye in future.

Progress in high-energy cosmic ray physics

Science.gov (United States)

Mollerach, S.; Roulet, E.

2018-01-01

We review some of the recent progress in our knowledge about high-energy cosmic rays, with an emphasis on the interpretation of the different observational results. We discuss the effects that are relevant to shape the cosmic ray spectrum and the explanations proposed to account for its features and for the observed changes in composition. The physics of air-showers is summarized and we also present the results obtained on the proton-air cross section and on the muon content of the showers. We discuss the cosmic ray propagation through magnetic fields, the effects of diffusion and of magnetic lensing, the cosmic ray interactions with background radiation fields and the production of secondary neutrinos and photons. We also consider the cosmic ray anisotropies, both at large and small angular scales, presenting the results obtained from the TeV up to the highest energies and discuss the models proposed to explain their origin.

To the problem of superfluous cosmic radiation

International Nuclear Information System (INIS)

Savenko, I.A.; Saraeva, M.A.; Shavrin, P.I.

1979-01-01

From consideration of a number of basic works on the excessive cosmic radiation given is the most probable composition (electron, proton, and nuclear components) of this radiation in equatorial regions at altitudes corresponding to minimum altitudes of the drift trajectories hsub(min) <= 0, in case of detecting by detector on the artificial satellite of the Earth (ASE) with the mass up to 1t and of the heavier ASE. The disagreement in spectra of solar cosmic rays obtained along the latitude effect on the ASE. ''Molniya-1'' and in the experiments out of the magnetosphere on the ASE ''Explorer-41'' is explained by excessive radiation production of solar cosmic rays. The comparison of readings of the neutron channel with those of the charged particle channels of the apparatus on the ASE ''Molniya-1'' during the proton event on 25.01.1971 does not contradict to the supposition on the similarity of excessive cosmic radiation production of galactic and solar cosmic rays

LHCf sheds new light on cosmic rays

CERN Multimedia

Anaïs Schaeffer

2011-01-01

The energy spectrum of the single photon obtained using data from the LHCf experiment has turned out to be very different from that predicted by the theoretical models used until now to describe the interactions between very high-energy cosmic rays and the earth's atmosphere. The consequences of this discrepancy for cosmic ray studies could be significant.   Artistic impression of cosmic rays entering Earth's atmosphere. (Credit: Asimmetrie/Infn). It took physicists by surprise when analysis of the data collected by the two LHCf calorimeters in 2010 showed that high-energy cosmic rays don't interact with the atmosphere in the manner predicted by theory. The LHCf detectors, set up 140 metres either side of the ATLAS interaction point, are dedicated to the study of the secondary particles emitted at very small angles during proton-proton collisions in the LHC, with energies comparable to cosmic rays entering the earth's atmosphere at 2.5x1016 eV. The aim of the experiment is to r...

Cosmic rays and tests of fundamental principles

Science.gov (United States)

Gonzalez-Mestres, Luis

2011-03-01

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.

Cosmic rays and tests of fundamental principles

International Nuclear Information System (INIS)

Gonzalez-Mestres, Luis

2011-01-01

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.

Particle Acceleration in Mildly Relativistic Shearing Flows: The Interplay of Systematic and Stochastic Effects, and the Origin of the Extended High-energy Emission in AGN Jets

Energy Technology Data Exchange (ETDEWEB)

Liu, Ruo-Yu; Rieger, F. M.; Aharonian, F. A., E-mail: ruoyu@mpi-hd.mpg.de, E-mail: frank.rieger@mpi-hd.mpg.de, E-mail: aharon@mpi-hd.mpg.de [Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)

2017-06-10

The origin of the extended X-ray emission in the large-scale jets of active galactic nuclei (AGNs) poses challenges to conventional models of acceleration and emission. Although electron synchrotron radiation is considered the most feasible radiation mechanism, the formation of the continuous large-scale X-ray structure remains an open issue. As astrophysical jets are expected to exhibit some turbulence and shearing motion, we here investigate the potential of shearing flows to facilitate an extended acceleration of particles and evaluate its impact on the resultant particle distribution. Our treatment incorporates systematic shear and stochastic second-order Fermi effects. We show that for typical parameters applicable to large-scale AGN jets, stochastic second-order Fermi acceleration, which always accompanies shear particle acceleration, can play an important role in facilitating the whole process of particle energization. We study the time-dependent evolution of the resultant particle distribution in the presence of second-order Fermi acceleration, shear acceleration, and synchrotron losses using a simple Fokker–Planck approach and provide illustrations for the possible emergence of a complex (multicomponent) particle energy distribution with different spectral branches. We present examples for typical parameters applicable to large-scale AGN jets, indicating the relevance of the underlying processes for understanding the extended X-ray emission and the origin of ultrahigh-energy cosmic rays.

Low-energy cosmic rays in the Orion region

DEFF Research Database (Denmark)

Pohl, M.

1998-01-01

The recently observed nuclear gamma-ray line emission from the Orion complex implies a high flux of low-energy cosmic rays (LECR) with unusual abundance. This cosmic ray component would dominate the energy density, pressure, and ionising power of cosmic rays, and thus would have a strong impact...

Does a cosmic censor exist

International Nuclear Information System (INIS)

Israel, W.

1984-01-01

A distinction is drawn between the event horizon conjecture (EHC), the conjecture that an event horizon forms in a gravitational collapse, and cosmic censorship, the idea that every singularity which develops in the course of collapse must be enclosed within a horizon. It is argued that a body of circumstantial evidence seems to favor EHC, but cosmic censorship seems contraindicated

Viscous self interacting dark matter and cosmic acceleration

Science.gov (United States)

Atreya, Abhishek; Bhatt, Jitesh R.; Mishra, Arvind

2018-02-01

Self interacting dark matter (SIDM) provides us with a consistent solution to certain astrophysical observations in conflict with collision-less cold DM paradigm. In this work we estimate the shear viscosity (η) and bulk viscosity (ζ) of SIDM, within kinetic theory formalism, for galactic and cluster size SIDM halos. To that extent we make use of the recent constraints on SIDM cross-section for the dwarf galaxies, LSB galaxies and clusters. We also estimate the change in solution of Einstein's equation due to these viscous effects and find that σ/m constraints on SIDM from astrophysical data provide us with sufficient viscosity to account for the observed cosmic acceleration at present epoch, without the need of any additional dark energy component. Using the estimates of dark matter density for galactic and cluster size halo we find that the mean free path of dark matter ~ few Mpc. Thus the smallest scale at which the viscous effect start playing the role is cluster scale. Astrophysical data for dwarf, LSB galaxies and clusters also seems to suggest the same. The entire analysis is independent of any specific particle physics motivated model for SIDM.

Diffuse fluxes of cosmic high-energy neutrinos

International Nuclear Information System (INIS)

Stecker, F.W.

1979-01-01

Production spectra of high-energy neutrinos from galactic cosmic-ray interactions with interstellar gas and extragalactic ultrahigh-energy cosmic-ray interactions with microwave blackbody photons are presented and discussed. These production processes involve the decay of charged pions and are thus related to the production of cosmic γ-rays from the decay of neutral pions. Estimates of the neutrino fluxes from various diffuse cosmic sources are then made, and the reasons for significant differences with previous estimates are discussed. Small predicted event rates for a DUMAND type detection system, combined with a possible significant flux of prompt neutrinos from the atmosphere above 50 TeV, may make the study of diffuse extraterrestrial neutrinos more difficult than previously thought

Cosmic Rays and Climate

CERN Document Server

Kirkby, Jasper

2007-01-01

Among the most puzzling questions in climate change is that of solar-climate variability, which has attracted the attention of scientists for more than two centuries. Until recently, even the existence of solar-climate variability has been controversial—perhaps because the observations had largely involved correlations between climate and the sunspot cycle that had persisted for only a few decades. Over the last few years, however, diverse reconstructions of past climate change have revealed clear associations with cosmic ray variations recorded in cosmogenic isotope archives, providing persuasive evidence for solar or cosmic ray forcing of the climate. However, despite the increasing evidence of its importance, solar-climate variability is likely to remain controversial until a physical mechanism is established. Although this remains a mystery, observations suggest that cloud cover may be influenced by cosmic rays, which are modulated by the solar wind and, on longer time scales, by the geomagnetic fiel...

Atmospheric and biospheric effects of cosmic

International Nuclear Information System (INIS)

Cardenas, Rolando

2007-01-01

We briefly review and classify the action that different sources of cosmic radiations might have had on Earth climate and biosphere in the geological past and at present times. We present the action of both sparse explosive phenomena, like gamma-ray bursts and supernovae, and permanent ones like cosmic rays and ultraviolet radiation backgrounds. Very energetic cosmic radiation coming from explosions can deplete the ozone lawyer due to initial ionization reactions, while soft backgrounds might trigger low altitude cloud formation through certain microphysical amplification processes. We examine a hypothesis concerning the potential role of cosmic rays on present Global Climatic Change. We also present the potential of UV astronomy to probe some of above scenarios, and speak on the possibilities for the Cuban participation in the international mega-project World Space Observatory, a UV telescope to be launched in the period 2007-2009. (Author)

Relative viscosity of emulsions in simple shear flow: Temperature, shear rate, and interfacial tension dependence

Energy Technology Data Exchange (ETDEWEB)

Choi, Se Bin; Lee, Joon Sang [Dept. of Mechanical Engineering, Yonsei Unversity, Seoul (Korea, Republic of)

2015-08-15

We simulate an emulsion system under simple shear rates to analyze its rheological characteristics using the lattice Boltzmann method (LBM). We calculate the relative viscosity of an emulsion under a simple shear flow along with changes in temperature, shear rate, and surfactant concentration. The relative viscosity of emulsions decreased with an increase in temperature. We observed the shear-thinning phenomena, which is responsible for the inverse proportion between the shear rate and viscosity. An increase in the interfacial tension caused a decrease in the relative viscosity of the decane-in-water emulsion because the increased deformation caused by the decreased interfacial tension significantly influenced the wall shear stress.

Cosmic ray riddle solved?

International Nuclear Information System (INIS)

Anon.

1995-01-01

Full text: Physicists from Japan and the United States have discovered a possible answer to the puzzle of the origin of high energy cosmic rays that bombard Earth from all directions in space. Using data from the Japanese/US X-ray astronomical satellite ASCA, physicists have found strong evidence for the production of cosmic particles in the shock wave of a supernova remnant, the expanding fireball produced by the explosion of a star. Primary cosmic rays, mostly electrons and protons, travel near the speed of light. Each second, approximately 4 such particles cross one square centimetre of space just outside the Earth's atmosphere. Subsequently, collisions of these primary particles with atoms in the upper atmosphere produce slower secondary particles. Ever since the discovery of cosmic rays early this century, scientists have debated the origin of these particles and how they can be accelerated to such high speeds. Supernova remnants have long been thought to provide the high energy component, but the evidence has been lacking until now. The international team of investigators used the satellite to determine that cosmic rays are generated profusely in the remains of the supernova of 1006 AD - which appeared to medieval viewers to be as bright as the Moon - and that they are accelerated to high velocities by an iterative process first suggested by Enrico Fermi in 1949. Using solid-state X-ray cameras, the ASCA satellite records simultaneous images and spectra of X-rays from celestial sources, allowing astronomers to distinguish different types of X-ray emission. The tell-tale clue to the discovery was the detection of two diametrically opposite regions in the rapidly expanding supernova remnant, the debris from the stellar explosion. The two regions glow intensely from the synchrotron radiation produced when fast-moving electrons are bent by a magnetic field. The remainder of the supernova remnant, in contrast, emits ordinary ''thermal'' X

High-flow-velocity and shear-rate imaging by use of color Doppler optical coherence tomography

NARCIS (Netherlands)

van Leeuwen, T. G.; Kulkarni, M. D.; Yazdanfar, S.; Rollins, A. M.; Izatt, J. A.

1999-01-01

Color Doppler optical coherence tomography (CDOCT) is capable of precise velocity mapping in turbid media. Previous CDOCT systems based on the short-time Fourier transform have been limited to maximum flow velocities of the order of tens of millimeters per second. We describe a technique, based on

Cosmic Ray Interactions in Shielding Materials

International Nuclear Information System (INIS)

Aguayo Navarrete, Estanislao; Kouzes, Richard T.; Ankney, Austin S.; Orrell, John L.; Berguson, Timothy J.; Troy, Meredith D.

2011-01-01

This document provides a detailed study of materials used to shield against the hadronic particles from cosmic ray showers at Earth's surface. This work was motivated by the need for a shield that minimizes activation of the enriched germanium during transport for the MAJORANA collaboration. The materials suitable for cosmic-ray shield design are materials such as lead and iron that will stop the primary protons, and materials like polyethylene, borated polyethylene, concrete and water that will stop the induced neutrons. The interaction of the different cosmic-ray components at ground level (protons, neutrons, muons) with their wide energy range (from kilo-electron volts to giga-electron volts) is a complex calculation. Monte Carlo calculations have proven to be a suitable tool for the simulation of nucleon transport, including hadron interactions and radioactive isotope production. The industry standard Monte Carlo simulation tool, Geant4, was used for this study. The result of this study is the assertion that activation at Earth's surface is a result of the neutronic and protonic components of the cosmic-ray shower. The best material to shield against these cosmic-ray components is iron, which has the best combination of primary shielding and minimal secondary neutron production.

Shear banding, discontinuous shear thickening, and rheological phase transitions in athermally sheared frictionless disks

Science.gov (United States)

Vâgberg, Daniel; Olsson, Peter; Teitel, S.

2017-05-01

We report on numerical simulations of simple models of athermal, bidisperse, soft-core, massive disks in two dimensions, as a function of packing fraction ϕ , inelasticity of collisions as measured by a parameter Q , and applied uniform shear strain rate γ ˙. Our particles have contact interactions consisting of normally directed elastic repulsion and viscous dissipation, as well as tangentially directed viscous dissipation, but no interparticle Coulombic friction. Mapping the phase diagram in the (ϕ ,Q ) plane for small γ ˙, we find a sharp first-order rheological phase transition from a region with Bagnoldian rheology to a region with Newtonian rheology, and show that the system is always Newtonian at jamming. We consider the rotational motion of particles and demonstrate the crucial importance that the coupling between rotational and translational degrees of freedom has on the phase structure at small Q (strongly inelastic collisions). At small Q , we show that, upon increasing γ ˙, the sharp Bagnoldian-to-Newtonian transition becomes a coexistence region of finite width in the (ϕ ,γ ˙) plane, with coexisting Bagnoldian and Newtonian shear bands. Crossing this coexistence region by increasing γ ˙ at fixed ϕ , we find that discontinuous shear thickening can result if γ ˙ is varied too rapidly for the system to relax to the shear-banded steady state corresponding to the instantaneous value of γ ˙.

Cosmic gamma-ray background radiation. Current understandings and problems

International Nuclear Information System (INIS)

Inoue, Yoshiyuki

2015-01-01

The cosmic gamma-ray background radiation is one of the most fundamental observables in the gamma-ray band. Although the origin of the cosmic gamma-ray background radiation has been a mystery for a long time, the Fermi gamma-ray space telescope has recently measured it at 0.1-820 GeV and revealed that the cosmic GeV gamma-ray background is composed of blazars, radio galaxies, and star-forming galaxies. However, Fermi still leaves the following questions. Those are dark matter contribution, origins of the cosmic MeV gamma-ray background, and the connection to the IceCube TeV-PeV neutrino events. In this proceeding, I will review the current understandings of the cosmic gamma-ray background and discuss future prospects of cosmic gamma-ray background radiation studies. (author)

Phenomenology of cosmic phase transitions

International Nuclear Information System (INIS)

Kaempfer, B.; Lukacs, B.; Paal, G.

1989-11-01

The evolution of the cosmic matter from Planck temperature to the atomic combination temperature is considered from a phenomenological point of view. Particular emphasis is devoted to the sequence of cosmic phase transitions. The inflationary era at the temperature of the order of the grand unification energy scale and the quantum chromodynamic confinement transition are dealt with in detail. (author) 131 refs.; 26 figs

Cosmic microwave background, where next?

CERN Multimedia

CERN. Geneva

2009-01-01

Ground-based, balloon-borne and space-based experiments will observe the Cosmic Microwave Background in greater details to address open questions about the origin and the evolution of the Universe. In particular, detailed observations the polarization pattern of the Cosmic Microwave Background radiation have the potential to directly probe physics at the GUT scale and illuminate aspects of the physics of the very early Universe.

Cosmic rays and Earth's climate

DEFF Research Database (Denmark)

Svensmark, Henrik

2000-01-01

During the last solar cycle the Earth's cloud cover underwent a modulation in phase with the cosmic ray flux. Assuming that there is a causal relationship between the two, it is expected and found that the Earth's temperature follows more closely decade variations in cosmic ray flux than other...... solar activity parameters. If the relationship is real the state of the Heliosphere affects the Earth's climate....

The Spine of the Cosmic Web

NARCIS (Netherlands)

Aragón-Calvo, Miguel A.; Platen, Erwin; van de Weijgaert, Rien; Szalay, Alexander S.

2010-01-01

We present the SpineWeb framework for the topological analysis of the Cosmic Web and the identification of its walls, filaments, and cluster nodes. Based on the watershed segmentation of the cosmic density field, the SpineWeb method invokes the local adjacency properties of the boundaries between

The Spine of the Cosmic Web

NARCIS (Netherlands)

Aragón-Calvo, Miguel A.; Platen, Erwin; van de Weijgaert, Rien; Szalay, Alexander S.

We present the SpineWeb framework for the topological analysis of the Cosmic Web and the identification of its walls, filaments, and cluster nodes. Based on the watershed segmentation of the cosmic density field, the SpineWeb method invokes the local adjacency properties of the boundaries between

NEXUS: tracing the cosmic web connection

NARCIS (Netherlands)

Cautun, Marius; van de Weygaert, Rien; Jones, Bernard J. T.

2013-01-01

We introduce the NEXUS algorithm for the identification of cosmic web environments: clusters, filaments, walls and voids. This is a multiscale and automatic morphological analysis tool that identifies all the cosmic structures in a scale free way, without preference for a certain size or shape. We

Analysis of the Shear Behavior of Stubby Y-Type Perfobond Rib Shear Connectors for a Composite Frame Structure.

Science.gov (United States)

Kim, Sang-Hyo; Kim, Kun-Soo; Lee, Do-Hoon; Park, Jun-Seung; Han, Oneil

2017-11-22

Shear connectors are used in steel beam-concrete slabs of composite frame and bridge structures to transfer shear force according to design loads. The existing Y-type perfobond rib shear connectors are designed for girder slabs of composite bridges. Therefore, the rib and transverse rebars of the conventional Y-type perfobond rib shear connectors are extremely large for the composite frames of building structures. Thus, this paper proposes stubby Y-type perfobond rib shear connectors, redefining the existing connectors, for composite frames of building structures; these were used to perform push-out tests. These shear connectors have relatively small ribs compared to the conventional Y-type perfobond rib shear connectors. To confirm the shear resistance of these stubby shear connectors, we performed an experiment by using transverse rebars D13 and D16. The results indicate that these shear connectors have suitable shear strength and ductility for application in composite frame structures. The shear strengths obtained using D13 and D16 were not significantly different. However, the ductility of the shear connectors with D16 was 45.1% higher than that of the shear connectors with D13.

Smooth halos in the cosmic web

Energy Technology Data Exchange (ETDEWEB)

Gaite, José, E-mail: jose.gaite@upm.es [Physics Dept., ETSIAE, IDR, Universidad Politécnica de Madrid, Pza. Cardenal Cisneros 3, E-28040 Madrid (Spain)

2015-04-01

Dark matter halos can be defined as smooth distributions of dark matter placed in a non-smooth cosmic web structure. This definition of halos demands a precise definition of smoothness and a characterization of the manner in which the transition from smooth halos to the cosmic web takes place. We introduce entropic measures of smoothness, related to measures of inequality previously used in economy and with the advantage of being connected with standard methods of multifractal analysis already used for characterizing the cosmic web structure in cold dark matter N-body simulations. These entropic measures provide us with a quantitative description of the transition from the small scales portrayed as a distribution of halos to the larger scales portrayed as a cosmic web and, therefore, allow us to assign definite sizes to halos. However, these ''smoothness sizes'' have no direct relation to the virial radii. Finally, we discuss the influence of N-body discreteness parameters on smoothness.

Lightning Discharges, Cosmic Rays and Climate

Science.gov (United States)

Kumar, Sanjay; Siingh, Devendraa; Singh, R. P.; Singh, A. K.; Kamra, A. K.

2018-03-01

The entirety of the Earth's climate system is continuously bombarded by cosmic rays and exhibits about 2000 thunderstorms active at any time of the day all over the globe. Any linkage among these vast systems should have global consequences. Numerous studies done in the past deal with partial links between some selected aspects of this grand linkage. Results of these studies vary from weakly to strongly significant and are not yet complete enough to justify the physical mechanism proposed to explain such links. This review is aimed at presenting the current understanding, based on the past studies on the link between cosmic ray, lightning and climate. The deficiencies in some proposed links are pointed out. Impacts of cosmic rays on engineering systems and the possible effects of cosmic rays on human health are also briefly discussed. Also enumerated are some problems for future work which may help in developing the grand linkage among these three vast systems.

Cosmic ray propagation with CRPropa 3

International Nuclear Information System (INIS)

Batista, R Alves; Evoli, C; Sigl, G; Van Vliet, A; Erdmann, M; Kuempel, D; Mueller, G; Walz, D; Kampert, K-H; Winchen, T

2015-01-01

Solving the question of the origin of ultra-high energy cosmic rays (UHECRs) requires the development of detailed simulation tools in order to interpret the experimental data and draw conclusions on the UHECR universe. CRPropa is a public Monte Carlo code for the galactic and extragalactic propagation of cosmic ray nuclei above ∼ 10 17 eV, as well as their photon and neutrino secondaries. In this contribution the new algorithms and features of CRPropa 3, the next major release, are presented. CRPropa 3 introduces time-dependent scenarios to include cosmic evolution in the presence of cosmic ray deflections in magnetic fields. The usage of high resolution magnetic fields is facilitated by shared memory parallelism, modulated fields and fields with heterogeneous resolution. Galactic propagation is enabled through the implementation of galactic magnetic field models, as well as an efficient forward propagation technique through transformation matrices. To make use of the large Python ecosystem in astrophysics CRPropa 3 can be steered and extended in Python. (paper)

Smooth halos in the cosmic web

International Nuclear Information System (INIS)

Gaite, José

2015-01-01

Dark matter halos can be defined as smooth distributions of dark matter placed in a non-smooth cosmic web structure. This definition of halos demands a precise definition of smoothness and a characterization of the manner in which the transition from smooth halos to the cosmic web takes place. We introduce entropic measures of smoothness, related to measures of inequality previously used in economy and with the advantage of being connected with standard methods of multifractal analysis already used for characterizing the cosmic web structure in cold dark matter N-body simulations. These entropic measures provide us with a quantitative description of the transition from the small scales portrayed as a distribution of halos to the larger scales portrayed as a cosmic web and, therefore, allow us to assign definite sizes to halos. However, these ''smoothness sizes'' have no direct relation to the virial radii. Finally, we discuss the influence of N-body discreteness parameters on smoothness

Cosmic ray antimatter and baryon symmetric cosmology

Science.gov (United States)

Stecker, F. W.; Protheroe, R. J.; Kazanas, D.

1982-01-01

The relative merits and difficulties of the primary and secondary origin hypotheses for the observed cosmic-ray antiprotons, including the new low-energy measurement of Buffington, et al. We conclude that the cosmic-ray antiproton data may be evidence for antimatter galaxies and baryon symmetric cosmology. The present bar P data are consistent with a primary extragalactic component having /p=/equiv 1+/- 3.2/0.7x10 = to the -4 independent of energy. We propose that the primary extragalactic cosmic ray antiprotons are most likely from active galaxies and that expected disintegration of bar alpha/alpha ban alpha/alpha. We further predict a value for ban alpha/alpha =/equiv 10 to the -5, within range of future cosmic ray detectors.

Comparison of direct shear and simple shear responses of municipal solid waste in USA

KAUST Repository

Fei, Xunchang; Zekkos, Dimitrios

2017-01-01

Although large-size simple shear (SS) testing of municipal solid waste (MSW) may arguably provide a more realistic estimate of the shear strength (τ ) of MSW than the most commonly used direct shear (DS) testing, a systematic comparison between

Solar flares and the cosmic ray intensity

International Nuclear Information System (INIS)

Hatton, C.J.

1980-01-01

The relationship between the cosmic ray intensity and solar activity during solar cycle 20 is discussed. A model is developed whereby it is possible to simulate the observed cosmic ray intensity from the observed number of solar flares of importance >= 1. This model leads to a radius for the modulation region of 60-70 AU. It is suggested that high speed solar streams also made a small contribution to the modulation of cosmic rays during solar cycle 20. (orig.)

Cosmic-ray-modified stellar winds. III. A numerical iterative approach

International Nuclear Information System (INIS)

Ko, C.M.; Jokipii, J.R.; Webb, G.M.

1988-01-01

A numerical iterative method is used to determine the modification of a stellar wind flow with a termination shock by the galactic cosmic rays. A two-fluid model consisting of cosmic rays and thermal stellar wind gas is used in which the cosmic rays are coupled to the background flow via scattering with magnetohydrodynamic waves or irregularities. A polytropic model is used to describe the thermal stellar wind gas, and the cosmic-rays are modeled as a hot, low-density gas with negligible mass flux. The positive galactic cosmic-ray pressure gradient serves to brake the outflowing stellar wind gas, and the cosmic rays modify the location of the critical point of the wind, the location of the shock, the wind fluid velocity profile, and the thermal gas entropy constants on both sides of the shock. The transfer of energy to the cosmic rays results in an outward radial flux of cosmic-ray energy. 21 references

A disintegrating cosmic string

International Nuclear Information System (INIS)

Griffiths, J B; Docherty, P

2002-01-01

We present a simple sandwich gravitational wave of the Robinson-Trautman family. This is interpreted as representing a shock wave with a spherical wavefront which propagates into a Minkowski background minus a wedge (i.e. the background contains a cosmic string). The deficit angle (the tension) of the string decreases through the gravitational wave, which then ceases. This leaves an expanding spherical region of Minkowski space behind it. The decay of the cosmic string over a finite interval of retarded time may be considered to generate the gravitational wave. (letter to the editor)

Direct observation of lubricant additives using tomography techniques

Energy Technology Data Exchange (ETDEWEB)

Chen, Yunyun [Department of Materials Science and Engineering, Texas A& M University, College Station, Texas 77843 (United States); Sanchez, Carlos [Mechanical Engineering, Texas A& M University, College Station, Texas 77843 (United States); Parkinson, Dilworth Y. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Liang, Hong, E-mail: hliang@tamu.edu [Department of Materials Science and Engineering, Texas A& M University, College Station, Texas 77843 (United States); Mechanical Engineering, Texas A& M University, College Station, Texas 77843 (United States)

2016-07-25

Lubricants play important roles in daily activities such as driving, walking, and cooking. The current understanding of mechanisms of lubrication, particularly in mechanical systems, has been limited by the lack of capability in direct observation. Here, we report an in situ approach to directly observe the motion of additive particles in grease under the influence of shear. Using the K-edge tomography technique, it is possible to detect particular additives in a grease and observe their distribution through 3D visualization. A commercial grease as a reference was studied with and without an inorganic additive of Fe{sub 3}O{sub 4} microparticles. The results showed that it was possible to identify these particles and track their movement. Under a shear stress, Fe{sub 3}O{sub 4} particles were found to adhere to the edge of calcium complex thickeners commonly used in grease. Due to sliding, the grease formed a film with increased density. This approach enables in-line monitoring of a lubricant and future investigation in mechanisms of lubrication.

Feasibility study on a cosmic-ray level gauge

International Nuclear Information System (INIS)

Matsuda, H.; Fukaya, M.; Minato, S.

1989-01-01

Cosmic-ray intensities were measured at the stairs in a subway station in Nagoya City, inside a tall concrete building and under a cylindrical water tank, to examine the feasibility of a cosmic-ray level gauge. The measured results agreed quite well with the theoretical calculations. These results show that a cosmic-ray level gauge is feasible. (author)

Semiconductor laser shearing interferometer

International Nuclear Information System (INIS)

Ming Hai; Li Ming; Chen Nong; Xie Jiaping

1988-03-01

The application of semiconductor laser on grating shearing interferometry is studied experimentally in the present paper. The method measuring the coherence of semiconductor laser beam by ion etching double frequency grating is proposed. The experimental result of lens aberration with semiconductor laser shearing interferometer is given. Talbot shearing interferometry of semiconductor laser is also described. (author). 2 refs, 9 figs

One century of cosmic rays – A particle physicist's view

Directory of Open Access Journals (Sweden)

Sutton Christine

2015-01-01

Full Text Available Experiments on cosmic rays and the elementary particles share a common history that dates back to the 19th century. Following the discovery of radioactivity in the 1890s, the paths of the two fields intertwined, especially during the decades after the discovery of cosmic rays. Experiments demonstrated that the primary cosmic rays are positively charged particles, while other studies of cosmic rays revealed various new sub-atomic particles, including the first antiparticle. Techniques developed in common led to the birth of neutrino astronomy in 1987 and the first observation of a cosmic γ-ray source by a ground-based cosmic-ray telescope in 1989.

Comparison of direct shear and simple shear responses of municipal solid waste in USA

KAUST Repository

Fei, Xunchang

2017-10-25

Although large-size simple shear (SS) testing of municipal solid waste (MSW) may arguably provide a more realistic estimate of the shear strength (τ ) of MSW than the most commonly used direct shear (DS) testing, a systematic comparison between the shear responses of MSW obtained from the two testing methods is lacking. In this study, a large-size shear device was used to test identical MSW specimens sampled in USA in DS and SS. Eight DS tests and 11 SS tests were conducted at vertical effective stresses of 50–500 kPa. The stress–displacement response of MSW in SS testing was hyperbolic and a maximum shear stress was reached, whereas a maximum shear stress was not reached in most DS tests. The τ, effective friction angle (ϕ ′) and cohesion (c ′) of MSW were obtained from DS and SS tests by using a displacement failure criterion of 40 mm. τ in SS testing was found to be equal to or lower than τ in DS testing with ratios of τ between 73 and 101%. SS testing resulted in higher ϕ ′ but lower c ′ than DS testing. The shear strength parameters were lower than those obtained in previous studies from DS tests at 55 mm displacement.

Propagation of ultrahigh-energy cosmic rays

Energy Technology Data Exchange (ETDEWEB)

Stanev, Todor [Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)], E-mail: stanev@bartol.udel.edu

2009-06-15

We briefly describe the energy loss processes of ultrahigh-energy protons, heavier nuclei and {gamma}-rays in interactions with the universal photon fields of the Universe. We then discuss the modification of the accelerated cosmic-ray energy spectrum in propagation by the energy loss processes and the charged cosmic-ray scattering in the extragalactic magnetic fields. The energy lost by the ultrahigh-energy cosmic rays goes into {gamma}-rays and neutrinos that carry additional information about the sources of highest energy particles. The new experimental results of the HiRes and the Auger collaborations are discussed in view of the predictions from propagation calculations.

Fluctuations in the cosmic microwave background

International Nuclear Information System (INIS)

Banday, A.J.; Wolfendale, A.W.

1990-01-01

In view of the importance to contemporary cosmology, and to our understanding of the Universe, of the precise nature of the Cosmic Microwave Background (CMB) spectrum, we consider the effects on this spectrum of contamination by other radiation fields of both galactic and extragalactic origin. Particular attention is given to the significance of measurements of the fluctuations in the 'background' radiation detected at 10.46 GHz and we conclude that these fluctuations are of the same magnitude as those expected from galactic cosmic-ray effects. A more detailed study of the cosmic-ray induced fluctuations and measurements at higher frequencies will be needed before genuine CMB fluctuations can be claimed. (author)

Cosmic growth history and expansion history

International Nuclear Information System (INIS)

Linder, Eric V.

2005-01-01

The cosmic expansion history tests the dynamics of the global evolution of the universe and its energy density contents, while the cosmic growth history tests the evolution of the inhomogeneous part of the energy density. Precision comparison of the two histories can distinguish the nature of the physics responsible for the accelerating cosmic expansion: an additional smooth component--dark energy--or a modification of the gravitational field equations. With the aid of a new fitting formula for linear perturbation growth accurate to 0.05%-0.2%, we separate out the growth dependence on the expansion history and introduce a new growth index parameter γ that quantifies the gravitational modification

Experimental investigations into the shear behavior of self-compacting RC beams with and without shear reinforcement

Directory of Open Access Journals (Sweden)

Ammar N. HANOON

2014-12-01

Full Text Available Self-compacting concrete (SCC is a new generation of high-performance concrete, known for its excellent deformability and high resistance to segregation and bleeding. Nonetheless, SCC may be incapable of resisting shear because the shear resistance mechanisms of this concrete are uncertain, especially the aggregate interlock mechanism. This uncertainty is attributed to the fact that SCC contains a smaller amount of coarse aggregates than normal concrete (NC does. This study focuses on the shear strength of self-compacting reinforced concrete (RC beams with and without shear reinforcement. A total of 16 RC beam specimens was manufactured and tested in terms of shear span-to-depth ratio and flexural and shear reinforcement ratio. The test results were compared with those of the shear design equations developed by ACI, BS, CAN and NZ codes. Results show that an increase in web reinforcement enhanced cracking strength and ultimate load. Shear-tension failure was the control failure in all tested beams.

Confocal microscopy of colloidal dispersions in shear flow using a counter-rotating cone-plate shear cell

International Nuclear Information System (INIS)

Derks, Didi; Wisman, Hans; Blaaderen, Alfons van; Imhof, Arnout

2004-01-01

We report on novel possibilities for studying colloidal suspensions in a steady shear field in real space. Fluorescence confocal microscopy is combined with the use of a counter-rotating cone-plate shear cell. This allows imaging of individual particles in the bulk of a sheared suspension in a stationary plane. Moreover, this plane of zero velocity can be moved in the velocity gradient direction while keeping the shear rate constant. The colloidal system under study consists of rhodamine labelled PMMA spheres in a nearly density and refractive index matched mixture of cyclohexylbromide and cis-decalin. We show measured flow profiles in both the fluid and the crystalline phase and find indications for shear banding in the case of a sheared crystal. Furthermore, we show that, thanks to the counter-rotating principle of the cone-plate shear cell, a layer of particles in the bulk of a sheared crystalline suspension can be imaged for a prolonged time, with the result that their positions can be tracked

Robustness of cosmic neutrino background detection in the cosmic microwave background

Energy Technology Data Exchange (ETDEWEB)

Audren, Benjamin [Institut de Théorie des Phénomènes Physiques, École Polytechnique Fédérale de Lausanne, CH-1015, Lausanne (Switzerland); Bellini, Emilio; Cuesta, Antonio J.; Verde, Licia [Institut de Ciències del Cosmos, Universitat de Barcelona, IEEC-UB, Martí i Franquès 1, E08028 Barcelona (Spain); Gontcho, Satya Gontcho A; Pérez-Ràfols, Ignasi [Dept. d' Astronomia i Meteorologia, Institut de Ciències del Cosmos, Universitat de Barcelona, IEEC-UB, Martí i Franquès 1, E08028 Barcelona (Spain); Lesgourgues, Julien [CERN, Theory Division, CH-1211 Geneva 23 (Switzerland); Niro, Viviana [Departamento de Física Teórica, Universidad Autónoma de Madrid and Instituto de Física Teórica UAM/CSIC, Calle Nicolás Cabrera 13-15, Cantoblanco, E-28049 Madrid (Spain); Pellejero-Ibanez, Marcos; Tramonte, Denis [Instituto de Astrofísica de Canarias (IAC), C/Vía Láctea s/n, E-38200, La Laguna, Tenerife (Spain); Poulin, Vivian [LAPTh, Université de Savoie, CNRS, B.P.110, Annecy-le-Vieux F-74941 (France); Tram, Thomas, E-mail: emilio.bellini@icc.ub.edu [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth PO1 3FX (United Kingdom)

2015-03-01

The existence of a cosmic neutrino background can be probed indirectly by CMB experiments, not only by measuring the background density of radiation in the universe, but also by searching for the typical signatures of the fluctuations of free-streaming species in the temperature and polarisation power spectrum. Previous studies have already proposed a rather generic parametrisation of these fluctuations, that could help to discriminate between the signature of ordinary free-streaming neutrinos, or of more exotic dark radiation models. Current data are compatible with standard values of these parameters, which seems to bring further evidence for the existence of a cosmic neutrino background. In this work, we investigate the robustness of this conclusion under various assumptions. We generalise the definition of an effective sound speed and viscosity speed to the case of massive neutrinos or other dark radiation components experiencing a non-relativistic transition. We show that current bounds on these effective parameters do not vary significantly when considering an arbitrary value of the particle mass, or extended cosmological models with a free effective neutrino number, dynamical dark energy or a running of the primordial spectrum tilt. We conclude that it is possible to make a robust statement about the detection of the cosmic neutrino background by CMB experiments.

Investigation of modulus hardening of various co-clusters in aged Al-Cu-Mg-Ag alloy by atom probe tomography

Energy Technology Data Exchange (ETDEWEB)

Bai, Song [Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083 (China); School of Material Science and Engineering, Central South University, Changsha 410083 (China); Liu, Zhiyi, E-mail: liuzhiyi@csu.edu.cn [Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083 (China); School of Material Science and Engineering, Central South University, Changsha 410083 (China); Ying, Puyou; Wang, Jian; Li, Junlin [Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083 (China); School of Material Science and Engineering, Central South University, Changsha 410083 (China)

2016-06-21

The modulus hardening capability of various co-clusters in a low Cu/Mg ratio Al-Cu-Mg-Ag alloy aged at 165 °C is investigated by quantitative atom probe tomography analysis. Prolonged aging from 5 min to 2 h leads to the simultaneous increase in the critical shear stress of both Mg-Ag and Cu-Mg co-clusters. Regardless of the higher shear modulus of Cu-Mg co-clusters, calculation results show that Mg-Ag co-clusters possess a greater modulus hardening capability than Cu-Mg co-clusters, suggesting its primary contribution to the rapid hardening at the early aging stage. As aging extends from 30 min to 2 h, the increment in the critical shear stress of Mg-Ag co-clusters is lower than that of Cu-Mg co-clusters due to the precipitation of high density Ω phase. In addition, the shear modulus of Mg-Ag co-clusters is generally independent on its size at each investigated condition.

Investigation of modulus hardening of various co-clusters in aged Al-Cu-Mg-Ag alloy by atom probe tomography

International Nuclear Information System (INIS)

Bai, Song; Liu, Zhiyi; Ying, Puyou; Wang, Jian; Li, Junlin

2016-01-01

The modulus hardening capability of various co-clusters in a low Cu/Mg ratio Al-Cu-Mg-Ag alloy aged at 165 °C is investigated by quantitative atom probe tomography analysis. Prolonged aging from 5 min to 2 h leads to the simultaneous increase in the critical shear stress of both Mg-Ag and Cu-Mg co-clusters. Regardless of the higher shear modulus of Cu-Mg co-clusters, calculation results show that Mg-Ag co-clusters possess a greater modulus hardening capability than Cu-Mg co-clusters, suggesting its primary contribution to the rapid hardening at the early aging stage. As aging extends from 30 min to 2 h, the increment in the critical shear stress of Mg-Ag co-clusters is lower than that of Cu-Mg co-clusters due to the precipitation of high density Ω phase. In addition, the shear modulus of Mg-Ag co-clusters is generally independent on its size at each investigated condition.

Toward a RPC-based muon tomography system for cargo containers.

Science.gov (United States)

Baesso, P.; Cussans, D.; Thomay, C.; Velthuis, J.

2014-10-01

A large area scanner for cosmic muon tomography is currently being developed at University of Bristol. Thanks to their abundance and penetrating power, cosmic muons have been suggested as ideal candidates to scan large containers in search of special nuclear materials, which are characterized by high-Z and high density. The feasibility of such a scanner heavily depends on the detectors used to track the muons: for a typical container, the minimum required sensitive area is of the order of 100 2. The spatial resolution required depends on the geometrical configuration of the detectors. For practical purposes, a resolution of the order of 1 mm or better is desirable. A good time resolution can be exploited to provide momentum information: a resolution of the order of nanoseconds can be used to separate sub-GeV muons from muons with higher energies. Resistive plate chambers have a low cost per unit area and good spatial and time resolution; these features make them an excellent choice as detectors for muon tomography. In order to instrument a large area demonstrator we have produced 25 new readout boards and 30 glass RPCs. The RPCs measure 1800 mm× 600 mm and are read out using 1.68 mm pitch copper strips. The chambers were tested with a standardized procedure, i.e. without optimizing the working parameters to take into account differences in the manufacturing process, and the results show that the RPCs have an efficiency between 87% and 95%. The readout electronics show a signal to noise ratio greater than 20 for minimum ionizing particles. Spatial resolution better than 500 μm can easily be achieved using commercial read out ASICs. These results are better than the original minimum requirements to pass the tests and we are now ready to install the detectors.

Collisions of cosmic F- and D-strings

International Nuclear Information System (INIS)

Jones, N.

2004-01-01

Recent theoretical advances and upcoming experimental measurements make the testing of generic predictions of string theory models of cosmology feasible. Brane anti-brane models of inflation within superstring theory are promising as string theory descriptions of the physics of the early universe. While varied in their construction, these models can have the generic and observable consequence that cosmic strings will be abundant in the early universe. This leads to possible detectable effects in the cosmic microwave background, gravitational wave physics and gravitational lensing. Detailed calculations of cosmic string interactions within string theory are presented, in order to distinguish these cosmic strings from those in more conventional theories; these interaction probabilities can be very different from conventional 4-dimension strings, providing the possibility of experimental tests of string theory. (authors)

The hemodynamics in intracranial aneurysm ruptured region with active contrast leakage during computed tomography angiography

Science.gov (United States)

Li, Ming-Lung; Wang, Yi-Chou; Liou, Tong-Miin; Lin, Chao-An

2014-10-01

Precise locations of rupture region under contrast agent leakage of five ruptured cerebral artery aneurysms during computed tomography angiography, which is to our knowledge for the first time, were successfully identified among 101 patients. These, together with numerical simulations based on the reconstructed aneurysmal models, were used to analyze hemodynamic parameters of aneurysms under different cardiac cyclic flow rates. For side wall type aneurysms, different inlet flow rates have mild influences on the shear stresses distributions. On the other hand, for branch type aneurysms, the predicted wall shear stress (WSS) correlates strongly with the increase of inlet vessel velocity. The mean and time averaged WSSes at rupture regions are found to be lower than those over the surface of the aneurysms. Also, the levels of the oscillatory shear index (OSI) are higher than the reported threshold value, supporting the assertion that high OSI correlates with rupture of the aneurysm. However, the present results also indicate that OSI level at the rupture region is relatively lower.

Aerosols Produced by Cosmic Rays

DEFF Research Database (Denmark)

Enghoff, Martin Andreas Bødker

an experiment in order to investigate the underlying microphysical processes. The results of this experiment will help to understand whether ionization from cosmic rays, and by implication the related processes in the universe, has a direct influence on Earth’s atmosphere and climate. Since any physical...... mechanism linking cosmic rays to clouds and climate is currently speculative, there have been various suggestions of the role atmospheric ions may play; these involve any one of a number of processes from the nucleation of aerosols up to the collection processes of cloud droplets. We have chosen to start......Satellite observations have shown that the Earth’s cloud cover is strongly correlated with the galactic cosmic ray flux. While this correlation is indicative of a possible physical connection, there is currently no confirmation that a physical mechanism exists. We are therefore setting up...

Cosmic rays, clouds, and climate

DEFF Research Database (Denmark)

Marsh, N.; Svensmark, Henrik

2000-01-01

cloud radiative properties. Thus, a moderate influence on atmospheric aerosol distributions from cosmic ray ionisation would have a strong influence on the Earth's radiation budget. Historical evidence over the past 1000 years indicates that changes in climate have occurred in accord with variability......A correlation between a global average of low cloud cover and the flux of cosmic rays incident in the atmosphere has been observed during the last solar cycle. The ionising potential of Earth bound cosmic rays are modulated by the state of the heliosphere, while clouds play an important role...... in the Earth's radiation budget through trapping outgoing radiation and reflecting incoming radiation. If a physical link between these two features can be established, it would provide a mechanism linking solar activity and Earth's climate. Recent satellite observations have further revealed a correlation...

Cosmic Rays and Extensive Air Showers

CERN Document Server

Stanev, Todor

2010-01-01

We begin with a brief introduction of the cosmic ray energy spectrum and its main features. At energies higher than 105 GeV cosmic rays are detected by the showers they initiate in the atmosphere. We continues with a brief description of the energy spectrum and composition derived from air shower data.

The History of Cosmic Ray Studies after Hess

Energy Technology Data Exchange (ETDEWEB)

Grupen, Claus, E-mail: grupen@physik.uni-siegen.de

2013-06-15

The discovery of cosmic rays by Victor Hess was confirmed with balloon flights at higher altitudes by Kolhörster. Soon the interest turned into questions about the nature of cosmic rays: gamma rays or particles? Subsequent investigations have established cosmic rays as the birthplace of elementary particle physics. The 1936 Nobel prize was shared between Victor Hess and Carl Anderson. Anderson discovered the positron in a cloud chamber. The positron was predicted by Dirac several years earlier. Many new results came now from studies with cloud chambers and nuclear emulsions. Anderson and Neddermeyer saw the muon, which for some time was considered to be a candidate for the Yukawa particle responsible for nuclear binding. Lattes, Powell, Occhialini and Muirhead clarified the situation by the discovery of the charged pions in cosmic rays. Rochester and Butler found V's, which turned out to be short-lived neutral kaons decaying into a pair of charged pions. Λ's, Σ's and Ξ's were found in cosmic rays using nuclear emulsions. After that period, accelerators and storage rings took over. The unexpected renaissance of cosmic rays started with the search for solar neutrinos and the observation of the supernova 1987A and other accelerators in the sky. With the observation of neutrino oscillations one began to look beyond the standard model of elementary particles. After 100 years of cosmic ray research we are again at the beginning of a new era, and cosmic rays may contribute to solve the many open questions, like dark matter and dark energy, by providing energies well beyond those of earth-bound accelerators.

Excited waves in shear layers

Science.gov (United States)

Bechert, D. W.

1982-01-01

The generation of instability waves in free shear layers is investigated. The model assumes an infinitesimally thin shear layer shed from a semi-infinite plate which is exposed to sound excitation. The acoustical shear layer excitation by a source further away from the plate edge in the downstream direction is very weak while upstream from the plate edge the excitation is relatively efficient. A special solution is given for the source at the plate edge. The theory is then extended to two streams on both sides of the shear layer having different velocities and densities. Furthermore, the excitation of a shear layer in a channel is calculated. A reference quantity is found for the magnitude of the excited instability waves. For a comparison with measurements, numerical computations of the velocity field outside the shear layer were carried out.

COSMOS: the COsmic-ray Soil Moisture Observing System

Directory of Open Access Journals (Sweden)

M. Zreda

2012-11-01

Full Text Available The newly-developed cosmic-ray method for measuring area-average soil moisture at the hectometer horizontal scale is being implemented in the COsmic-ray Soil Moisture Observing System (or the COSMOS. The stationary cosmic-ray soil moisture probe measures the neutrons that are generated by cosmic rays within air and soil and other materials, moderated by mainly hydrogen atoms located primarily in soil water, and emitted to the atmosphere where they mix instantaneously at a scale of hundreds of meters and whose density is inversely correlated with soil moisture. The COSMOS has already deployed more than 50 of the eventual 500 cosmic-ray probes, distributed mainly in the USA, each generating a time series of average soil moisture over its horizontal footprint, with similar networks coming into existence around the world. This paper is written to serve a community need to better understand this novel method and the COSMOS project. We describe the cosmic-ray soil moisture measurement method, the instrument and its calibration, the design, data processing and dissemination used in the COSMOS project, and give example time series of soil moisture obtained from COSMOS probes.

High-energy cosmic-ray acceleration

OpenAIRE

Bustamante, M; Carrillo Montoya, G; de Paula, W; Duarte Chavez, J A; Gago, A M; Hakobyan, H; Jez, P; Monroy Montañez, J A; Ortiz Velasquez, A; Padilla Cabal, F; Pino Rozas, M; Rodriguez Patarroyo, D J; Romeo, G L; Saldaña-Salazar , U J; Velasquez, M

2010-01-01

We briefly review the basics of ultrahigh-energy cosmic-ray acceleration. The Hillas criterion is introduced as a geometrical criterion that must be fulfilled by potential acceleration sites, and energy losses are taken into account in order to obtain a more realistic scenario. The different available acceleration mechanisms are presented, with special emphasis on Fermi shock acceleration and its prediction of a power-law cosmic-ray energy spectrum. We conclude that first-order Fermi accelera...

Cosmic Rays in the Heliosphere: Requirements for Future Observations

Science.gov (United States)

Mewaldt, R. A.

2013-06-01

Since the publication of Cosmic Rays in the Heliosphere in 1998 there has been great progress in understanding how and why cosmic rays vary in space and time. This paper discusses measurements that are needed to continue advances in relating cosmic ray variations to changes in solar and interplanetary activity and variations in the local interstellar environment. Cosmic ray acceleration and transport is an important discipline in space physics and astrophysics, but it also plays a critical role in defining the radiation environment for humans and hardware in space, and is critical to efforts to unravel the history of solar activity. Cosmic rays are measured directly by balloon-borne and space instruments, and indirectly by ground-based neutron, muon and neutrino detectors, and by measurements of cosmogenic isotopes in ice cores, tree-rings, sediments, and meteorites. The topics covered here include: what we can learn from the deep 2008-2009 solar minimum, when cosmic rays reached the highest intensities of the space era; the implications of 10Be and 14C isotope archives for past and future solar activity; the effects of variations in the size of the heliosphere; opportunities provided by the Voyagers for discovering the origin of anomalous cosmic rays and measuring cosmic-ray spectra in interstellar space; and future space missions that can continue the exciting exploration of the heliosphere that has occurred over the past 50 years.

Rayleigh-wave phase-velocity maps and three-dimensional shear velocity structure of the western US from local non-plane surface wave tomography

Science.gov (United States)

Pollitz, F.F.; Snoke, J. Arthur

2010-01-01

We utilize two-and-three-quarter years of vertical-component recordings made by the Transportable Array (TA) component of Earthscope to constrain three-dimensional (3-D) seismic shear wave velocity structure in the upper 200 km of the western United States. Single-taper spectral estimation is used to compile measurements of complex spectral amplitudes from 44 317 seismograms generated by 123 teleseismic events. In the first step employed to determine the Rayleigh-wave phase-velocity structure, we implement a new tomographic method, which is simpler and more robust than scattering-based methods (e.g. multi-plane surface wave tomography). The TA is effectively implemented as a large number of local arrays by defining a horizontal Gaussian smoothing distance that weights observations near a given target point. The complex spectral-amplitude measurements are interpreted with the spherical Helmholtz equation using local observations about a succession of target points, resulting in Rayleigh-wave phase-velocity maps at periods over the range of 18–125 s. The derived maps depend on the form of local fits to the Helmholtz equation, which generally involve the nonplane-wave solutions of Friederich et al. In a second step, the phase-velocity maps are used to derive 3-D shear velocity structure. The 3-D velocity images confirm details witnessed in prior body-wave and surface-wave studies and reveal new structures, including a deep (>100 km deep) high-velocity lineament, of width ∼200 km, stretching from the southern Great Valley to northern Utah that may be a relic of plate subduction or, alternatively, either a remnant of the Mojave Precambrian Province or a mantle downwelling. Mantle seismic velocity is highly correlated with heat flow, Holocene volcanism, elastic plate thickness and seismicity. This suggests that shallow mantle structure provides the heat source for associated magmatism, as well as thinning of the thermal lithosphere, leading to relatively high

High-energy cosmic rays

Energy Technology Data Exchange (ETDEWEB)

Gaisser, Thomas K. [Bartol Research Institute, University of Delaware, Newark, DE 19716 (United States)]. E-mail: gaisser@bartol.udel.edu; Stanev, Todor [Bartol Research Institute, University of Delaware, Newark, DE 19716 (United States)

2006-10-17

After a brief review of galactic cosmic rays in the GeV to TeV energy range, we describe some current problems of interest for particles of very high energy. Particularly interesting are two features of the spectrum, the knee above 10{sup 15} eV and the ankle above 10{sup 18} eV. An important question is whether the highest-energy particles are of extra-galactic origin and, if so, at what energy the transition occurs. A theme common to all energy ranges is use of nuclear abundances as a tool for understanding the origin of the cosmic radiation.

Educational Cosmic Ray Arrays

International Nuclear Information System (INIS)

Soluk, R. A.

2006-01-01

In the last decade a great deal of interest has arisen in using sparse arrays of cosmic ray detectors located at schools as a means of doing both outreach and physics research. This approach has the unique advantage of involving grade school students in an actual ongoing experiment, rather then a simple teaching exercise, while at the same time providing researchers with the basic infrastructure for installation of cosmic ray detectors. A survey is made of projects in North America and Europe and in particular the ALTA experiment at the University of Alberta which was the first experiment operating under this paradigm

The absence of distortion in the cosmic microwave background spectrum and superconducting cosmic strings

International Nuclear Information System (INIS)

Sanchez, N.; Signore, M.

1990-01-01

From the results of recent measurements we place new constraints on superconducting cosmic strings (SCS) and on their cosmological evolution, independently of numerical simulation results. The absence of distortion in the cosmic microwave background radiation (MBR) spectrum recently reported from the preliminary data of the COBE (Cosmic background explorer) satellite, together with the available MBR angular temperature ΔT/T measurements and the latest fast pulsar timings, allow us to obtain (i) the electromagnetic-to-gravitational radiation ratio released by SCS loops, f -2 , (ii) the chemical potential due to SCS, μ 0SCS -3 , (iii) constraints on the loop evolution parameters which we confront to those given by numerical simulations, and (iv) limits on the string parameter Gμ: those obtained from COBE's data (Gμ -6 ) converge to those given by the latest PSR 1937+21 timing. Both limits on Gμ are reduced by an order of magnitude when taking into account numerical simulation results. (orig.)

Long-term and transient time variation of cosmic ray fluxes detected in Argentina by CARPET cosmic ray detector

Science.gov (United States)

De Mendonça, R. R. S.; Raulin, J.-P.; Bertoni, F. C. P.; Echer, E.; Makhmutov, V. S.; Fernandez, G.

2011-07-01

We present results obtained at El Leoncito (CASLEO, San Juan, Argentina) with the CARPET charged particles detector installed in April 2006. The observed modulation of the cosmic ray flux is discussed as a function of its time variability and it is related to longer solar activity variations and to shorter variations during solar and geomagnetic transient activity. Short period (few minutes, few hours) cosmic ray modulation events are observed during rain time (precipitation) and significant variations of the atmospheric electric field. Complementary observations of the atmospheric electric field indicate that its time variations play an important role in the detected cosmic ray event.

The ALTA cosmic ray experiment electronics system

International Nuclear Information System (INIS)

Brouwer, W.; Burris, W.J.; Caron, B.; Hewlett, J.; Holm, L.; Hamilton, A.; McDonald, W.J.; Pinfold, J.L.; Price, P.; Schaapman, J.R.; Sibley, L.; Soluk, R.A.; Wampler, L.J.

2005-01-01

Understanding the origin and propagation of high-energy cosmic rays is a fundamental area of astroparticle physics with major unanswered questions. The study of cosmic rays with energy more than 10 14 eV, probed only by ground-based experiments, has been restricted by the low particle flux. The Alberta Large-area Time-coincidence Array (ALTA) uses a sparse array of cosmic ray detection stations located in high schools across a large geographical area to search for non-random high-energy cosmic ray phenomena. Custom-built ALTA electronics is based on a modular board design. Its function is to control the detectors at each ALTA site allowing precise measurements of event timing and energy in the local detectors as well as time synchronization of all of the sites in the array using the global positioning system

Shear strength of non-shear reinforced concrete elements

DEFF Research Database (Denmark)

Hoang, Cao linh

1997-01-01

is based upon the hypothesis that cracks can be transformed into yield lines, which have lower sliding resistance than yield lines formed in uncracked concrete.Proposals have been made on how the derived standard solutions may be applied to more complicated cases, such as continuous beams, beams......The report deals with the shear strength of statically indeterminate reinforced concrete beams without shear reinforcement. Solutions for a number of beams with different load and support conditions have been derived by means of the crack sliding model developed by Jin- Ping Zhang.This model...

Experiments on sheet metal shearing

OpenAIRE

Gustafsson, Emil

2013-01-01

Within the sheet metal industry, different shear cutting technologies are commonly used in several processing steps, e.g. in cut to length lines, slitting lines, end cropping etc. Shearing has speed and cost advantages over competing cutting methods like laser and plasma cutting, but involves large forces on the equipment and large strains in the sheet material.Numerical models to predict forces and sheared edge geometry for different sheet metal grades and different shear parameter set-ups a...

Voids and the Cosmic Web: cosmic depression & spatial complexity

NARCIS (Netherlands)

van de Weygaert, Rien; Shandarin, S.; Saar, E.; Einasto, J.

2016-01-01

Voids form a prominent aspect of the Megaparsec distribution of galaxies and matter. Not only do theyrepresent a key constituent of the Cosmic Web, they also are one of the cleanest probesand measures of global cosmological parameters. The shape and evolution of voids are highly sensitive tothe

Experimental observation of shear thickening oscillation

DEFF Research Database (Denmark)

Nagahiro, Shin-ichiro; Nakanishi, Hiizu; Mitarai, Namiko

2013-01-01

We report experimental observations of the shear thickening oscillation, i.e. the spontaneous macroscopic oscillation in the shear flow of severe shear thickening fluid. Using a density-matched starch-water mixture, in the cylindrical shear flow of a few centimeters flow width, we observed...

Muon Production in Relativistic Cosmic-Ray Interactions

OpenAIRE

Klein, Spencer

2009-01-01

Cosmic-rays with energies up to $3\\times10^{20}$ eV have been observed. The nuclear composition of these cosmic rays is unknown but if the incident nuclei are protons then the corresponding center of mass energy is $\\sqrt{s_{nn}} = 700$ TeV. High energy muons can be used to probe the composition of these incident nuclei. The energy spectra of high-energy ($>$ 1 TeV) cosmic ray induced muons have been measured with deep underground or under-ice detectors. These muons come from pion and kaon de...

High energy cosmic rays: sources and fluxes

Energy Technology Data Exchange (ETDEWEB)

Stanev, Todor; Gaisser, Thomas K.; Tilav, Serap

2014-04-01

We discuss the production of a unique energy spectrum of the high energy cosmic rays detected with air showers by shifting the energy estimates of different detectors. After such a spectrum is generated we fit the spectrum with three or four populations of cosmic rays that might be accelerated at different cosmic ray sources. We also present the chemical composition that the fits of the spectrum generates and discuss some new data sets presented this summer at the ICRC in Rio de Janeiro that may require new global fits.

Ultra high-energy cosmic ray composition

International Nuclear Information System (INIS)

Longley, N.P.

1993-01-01

The Soudan 2 surface-underground cosmic ray experiment can simultaneously measure surface shower size, underground muon multiplicity, and underground muon separation for ultra high energy cosmic ray showers. These measurements are sensitive to the primary composition. Analysis for energies from 10 1 to 10 4 TeV favors a light flux consisting of predominantly H and He nuclei

Cosmic-ray exposure records and origins of meteorites

International Nuclear Information System (INIS)

Reedy, R.C.

1985-01-01

The cosmic-ray records of meteorites can be used to infer much about their origins and recent histories. Some meteorites had simple cosmic-ray exposure histories, while others had complex exposure histories with their cosmogenic products made both before and after a collision in space. The methods used to interpret meteorites' cosmic-ray records, especially identifying simple or complex exposure histories, often are inadequate. Besides spallogenic radionuclides and stable nuclides, measurements of products that have location-sensitive production rates, such as the tracks of heavy cosmic-ray nuclei or neutron-capture nuclides, are very useful in accurately determining a meteorite's history. Samples from different, known locations of a meteorite help in studying the cosmic-ray record. Such extensive sets of meteorite measurements, plus theoretical modeling of complex histories, will improve our ability to predict the production of cosmogenic nuclides in meteorites, to distinguish simple and complex exposure histories, and to better determine exposure ages

Ultrahigh Energy Cosmic Rays: Facts, Myths, and Legends

CERN Document Server

Anchordoqui, Luis Alfredo

2013-06-27

This is a written version of a series of lectures aimed at graduate students in astrophysics/particle theory/particle experiment. In the first part, we explain the important progress made in recent years towards understanding the experimental data on cosmic rays with energies > 10^8 GeV. We begin with a brief survey of the available data, including a description of the energy spectrum, mass composition, and arrival directions. At this point we also give a short overview of experimental techniques. After that, we introduce the fundamentals of acceleration and propagation in order to discuss the conjectured nearby cosmic ray sources, and emphasize some of the prospects for a new (multi-particle) astronomy. Next, we survey the state of the art regarding the ultrahigh energy cosmic neutrinos which should be produced in association with the observed cosmic rays. In the second part, we summarize the phenomenology of cosmic ray air showers. We explain the hadronic interaction models used to extrapolate results from ...

Shear behaviour of reinforced phyllite concrete beams

International Nuclear Information System (INIS)

Adom-Asamoah, Mark; Owusu Afrifa, Russell

2013-01-01

Highlights: ► Phyllite concrete beams often exhibited shear with anchorage bond failure. ► Different shear design provisions for reinforced phyllite beams are compared. ► Predicted shear capacity of phyllite beams must be modified by a reduction factor. -- Abstract: The shear behaviour of concrete beams made from phyllite aggregates subjected to monotonic and cyclic loading is reported. First diagonal shear crack load of beams with and without shear reinforcement was between 42–58% and 42–92% of the failure loads respectively. The phyllite concrete beams without shear links had lower post-diagonal cracking shear resistance compared to corresponding phyllite beams with shear links. As a result of hysteretic energy dissipation, limited cyclic loading affected the stiffness, strength and deformation of the phyllite beams with shear reinforcement. Generally, beams with and without shear reinforcement showed anchorage bond failure in addition to the shear failure due to high stress concentration near the supports. The ACI, BS and EC codes are conservative for the prediction of phyllite concrete beams without shear reinforcement but they all overestimate the shear strength of phyllite concrete beams with shear reinforcement. It is recommended that the predicted shear capacity of phyllite beams reinforced with steel stirrups be modified by a reduction factor of 0.7 in order to specify a high enough safety factor on their ultimate strength. It is also recommended that susceptibility of phyllite concrete beams to undergo anchorage bond failure is averted in design by the provision of greater anchorage lengths than usually permitted.

Cosmic string induced CMB maps

International Nuclear Information System (INIS)

Landriau, M.; Shellard, E. P. S.

2011-01-01

We compute maps of CMB temperature fluctuations seeded by cosmic strings using high resolution simulations of cosmic strings in a Friedmann-Robertson-Walker universe. We create full-sky, 18 deg. and 3 deg. CMB maps, including the relevant string contribution at each resolution from before recombination to today. We extract the angular power spectrum from these maps, demonstrating the importance of recombination effects. We briefly discuss the probability density function of the pixel temperatures, their skewness, and kurtosis.

Cosmic Ray Physics with the IceCube Observatory

International Nuclear Information System (INIS)

Kolanoski, H

2013-01-01

The IceCube Neutrino Observatory with its 1-km 3 in-ice detector and the 1-km 2 surface detector (IceTop) constitutes a three-dimensional cosmic ray detector well suited for general cosmic ray physics. Various measurements of cosmic ray properties, such as energy spectra, mass composition and anisotropies, have been obtained from analyses of air showers at the surface and/or atmospheric muons in the ice.

Interpreting the cosmic ray composition

Energy Technology Data Exchange (ETDEWEB)

O' C Drury, L.; Ellisson, D.C; Meyer, J.-P

2000-01-31

The detailed pattern of elemental abundances in the Galactic Cosmic Rays is well determined at energies of a few GeV per nucleon. After correction for propagation effects the inferred source composition shows significant deviations from the standard pattern of Galactic elemental abundances. These deviations, surprisingly overabundances of the heavy elements relative to Hydrogen, are clearly a significant clue to the origin of the cosmic rays, but one which has proven very difficult to interpret. We have recently shown that the 'standard' model for the origin of the bulk of the Galactic cosmic rays, namely acceleration by the diffusive shock acceleration process at the strong shocks associated with supernova remnants, can quantitatively explain all features of the source composition if the acceleration occurs from a dusty interstellar medium. This success must be regarded as one of the stronger pieces of evidence in favour of the standard model.

Cosmic Ray Energetics and Mass

CERN Multimedia

Baylon cardiel, J L; Wallace, K C; Anderson, T B; Copley, M

The cosmic-ray energetics and mass (CREAM) investigation is designed to measure cosmic-ray composition to the supernova energy scale of 10$^{15}$ eV in a series of ultra long duration balloon (ULDB) flights. The first flight is planned to be launched from Antarctica in December 2004. The goal is to observe cosmic-ray spectral features and/or abundance changes that might signify a limit to supernova acceleration. The particle ($\\{Z}$) measurements will be made with a timing-based charge detector and a pixelated silicon charge detector to minimize the effect of backscatter from the calorimeter. The particle energy measurements will be made with a transition radiation detector (TRD) for $\\{Z}$ > 3 and a sampling tungsten/scintillator calorimeter for $\\{Z}$ $\\geq$1 particles, allowing inflight cross calibration of the two detectors. The status of the payload construction and flight preparation are reported in this paper.

Interpreting the cosmic ray composition

International Nuclear Information System (INIS)

O'C Drury, L.; Ellisson, D.C; Meyer, J.-P.

2000-01-01

The detailed pattern of elemental abundances in the Galactic Cosmic Rays is well determined at energies of a few GeV per nucleon. After correction for propagation effects the inferred source composition shows significant deviations from the standard pattern of Galactic elemental abundances. These deviations, surprisingly overabundances of the heavy elements relative to Hydrogen, are clearly a significant clue to the origin of the cosmic rays, but one which has proven very difficult to interpret. We have recently shown that the 'standard' model for the origin of the bulk of the Galactic cosmic rays, namely acceleration by the diffusive shock acceleration process at the strong shocks associated with supernova remnants, can quantitatively explain all features of the source composition if the acceleration occurs from a dusty interstellar medium. This success must be regarded as one of the stronger pieces of evidence in favour of the standard model

To determine the slow shearing rate for consolidation drained shear box tests

Science.gov (United States)

Jamalludin, Damanhuri; Ahmad, Azura; Nordin, Mohd Mustaqim Mohd; Hashim, Mohamad Zain; Ibrahim, Anas; Ahmad, Fauziah

2017-08-01

Slope failures always occur in Malaysia especially during the rainy seasons. They cause damage to properties and fatalities. In this study, a total of 24 one dimensional consolidation tests were carried out on soil samples taken from 16 slope failures in Penang Island and in Baling, Kedah. The slope failures in Penang Island are within the granitic residual soil while in Baling, Kedah they are situated within the sedimentary residual soil. Most of the disturbed soil samples were taken at 100mm depth from the existing soil surface while some soil samples were also taken at 400, 700 and 1000mm depths from the existing soil surface. They were immediately placed in 2 layers of plastic bag to prevent moisture loss. Field bulk density tests were also carried out at all the locations where soil samples were taken. The field bulk density results were later used to re-compact the soil samples for the consolidation tests. The objective of the research is to determine the slow shearing rate to be used in consolidated drained shear box for residual soils taken from slope failures so that the effective shear strength parameters can be determined. One dimensional consolidation tests were used to determine the slow shearing rate. The slow shearing rate found in this study to be used in the consolidated drained shear box tests especially for Northern Malaysian residual soils was 0.286mm/minute.

Cosmic gamma bursts

International Nuclear Information System (INIS)

Ehstulin, I.V.

1980-01-01

A brief consideration is being given to the history of cosmic gamma burst discovery and modern knowledge of their properties. The time dependence of gamma bursts is described and their possible sources are discussed

Structure formation cosmic rays: Identifying observational constraints

Directory of Open Access Journals (Sweden)

Prodanović T.

2005-01-01

Full Text Available Shocks that arise from baryonic in-fall and merger events during the structure formation are believed to be a source of cosmic rays. These "structure formation cosmic rays" (SFCRs would essentially be primordial in composition, namely, mostly made of protons and alpha particles. However, very little is known about this population of cosmic rays. One way to test the level of its presence is to look at the products of hadronic reactions between SFCRs and the ISM. A perfect probe of these reactions would be Li. The rare isotope Li is produced only by cosmic rays, dominantly in αα → 6Li fusion reactions with the ISM helium. Consequently, this nuclide provides a unique diagnostic of the history of cosmic rays. Exactly because of this unique property is Li affected most by the presence of an additional cosmic ray population. In turn, this could have profound consequences for the Big-Bang nucleosynthesis: cosmic rays created during cosmic structure formation would lead to pre-Galactic Li production, which would act as a "contaminant" to the primordial 7Li content of metalpoor halo stars. Given the already existing problem of establishing the concordance between Li observed in halo stars and primordial 7Li as predicted by the WMAP, it is crucial to set limits to the level of this "contamination". However, the history of SFCRs is not very well known. Thus we propose a few model-independent ways of testing the SFCR species and their history, as well as the existing lithium problem: 1 we establish the connection between gamma-ray and Li production, which enables us to place constraints on the SFCR-made lithium by using the observed Extragalactic Gamma-Ray Background (EGRB; 2 we propose a new site for testing the primordial and SFCR-made lithium, namely, low-metalicity High-Velocity Clouds (HVCs, which retain the pre-Galactic composition without any significant depletion. Although using one method alone may not give us strong constraints, using them in

14. European cosmic ray symposium. Symposium program and abstracts

International Nuclear Information System (INIS)

1994-08-01

The abstracts of the 14. European Cosmic Ray Symposium are presented. The papers cover a large variety of topics in cosmic ray physics, both from the theoretical and the experimental point of view. Sun physics, and the effects on the inner heliosphere, the composition, and the properties of the primary and secondary cosmic radiation, galactic acceleration and the results of accelerator physics relevant to cosmic radiation physics, and the description and the results of large detector systems are presented. 63 items are indexed for INIS database. (K.A.)

Cosmic Censorship for Gowdy Spacetimes.

Science.gov (United States)

Ringström, Hans

2010-01-01

Due to the complexity of Einstein's equations, it is often natural to study a question of interest in the framework of a restricted class of solutions. One way to impose a restriction is to consider solutions satisfying a given symmetry condition. There are many possible choices, but the present article is concerned with one particular choice, which we shall refer to as Gowdy symmetry. We begin by explaining the origin and meaning of this symmetry type, which has been used as a simplifying assumption in various contexts, some of which we shall mention. Nevertheless, the subject of interest here is strong cosmic censorship. Consequently, after having described what the Gowdy class of spacetimes is, we describe, as seen from the perspective of a mathematician, what is meant by strong cosmic censorship. The existing results on cosmic censorship are based on a detailed analysis of the asymptotic behavior of solutions. This analysis is in part motivated by conjectures, such as the BKL conjecture, which we shall therefore briefly describe. However, the emphasis of the article is on the mathematical analysis of the asymptotics, due to its central importance in the proof and in the hope that it might be of relevance more generally. The article ends with a description of the results that have been obtained concerning strong cosmic censorship in the class of Gowdy spacetimes.

Grating-based tomography applications in biomedical engineering

Science.gov (United States)

Schulz, Georg; Thalmann, Peter; Khimchenko, Anna; Müller, Bert

2017-10-01

For the investigation of soft tissues or tissues consisting of soft and hard tissues on the microscopic level, hard X-ray phase tomography has become one of the most suitable imaging techniques. Besides other phase contrast methods grating interferometry has the advantage of higher sensitivity than inline methods and the quantitative results. One disadvantage of the conventional double-grating setup (XDGI) compared to inline methods is the limitation of the spatial resolution. This limitation can be overcome by removing the analyser grating resulting in a single-grating setup (XSGI). In order to verify the performance of XSGI concerning contrast and spatial resolution, a quantitative comparison of XSGI and XDGI tomograms of a human nerve was performed. Both techniques provide sufficient contrast to allow for the distinction of tissue types. The spatial resolution of the two-fold binned XSGI data set is improved by a factor of two in comparison to XDGI which underlies its performance in tomography of soft tissues. Another application for grating-based X-ray phase tomography is the simultaneous visualization of soft and hard tissues of a plaque-containing coronary artery. The simultaneous visualization of both tissues is important for the segmentation of the lumen. The segmented data can be used for flow simulations in order to obtain information about the three-dimensional wall shear stress distribution needed for the optimization of mechano-sensitive nanocontainers used for drug delivery.

How to detect the cosmic neutrino background?

International Nuclear Information System (INIS)

Ringwald, A.

2003-01-01

A measurement of the big bang relic neutrinos would open a new window to the early universe. We review various possibilities to detect this cosmic neutrino background and substantiate the assertion that - apart from the rather indirect evidence to be gained from cosmology and large-scale structure formation - the annihilation of ultrahigh energy cosmic neutrinos with relic anti-neutrinos (or vice versa) on the Z-resonance is a unique process having sensitivity to the relic neutrinos, if a sufficient flux at E ν i res =M Z 2 /(2m ν i )=4.10 22 eV (0.1 eV/m ν i ) exists. The associated absorption dips in the ultrahigh energy cosmic neutrino spectrum may be searched for at forthcoming neutrino and air shower detectors. The associated protons and photons may have been seen already in form of the cosmic ray events above the Greisen-Zatsepin-Kuzmin cutoff. (orig.)

Comparing cosmic web classifiers using information theory

Energy Technology Data Exchange (ETDEWEB)

Leclercq, Florent [Institute of Cosmology and Gravitation (ICG), University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth PO1 3FX (United Kingdom); Lavaux, Guilhem; Wandelt, Benjamin [Institut d' Astrophysique de Paris (IAP), UMR 7095, CNRS – UPMC Université Paris 6, Sorbonne Universités, 98bis boulevard Arago, F-75014 Paris (France); Jasche, Jens, E-mail: florent.leclercq@polytechnique.org, E-mail: lavaux@iap.fr, E-mail: j.jasche@tum.de, E-mail: wandelt@iap.fr [Excellence Cluster Universe, Technische Universität München, Boltzmannstrasse 2, D-85748 Garching (Germany)

2016-08-01

We introduce a decision scheme for optimally choosing a classifier, which segments the cosmic web into different structure types (voids, sheets, filaments, and clusters). Our framework, based on information theory, accounts for the design aims of different classes of possible applications: (i) parameter inference, (ii) model selection, and (iii) prediction of new observations. As an illustration, we use cosmographic maps of web-types in the Sloan Digital Sky Survey to assess the relative performance of the classifiers T-WEB, DIVA and ORIGAMI for: (i) analyzing the morphology of the cosmic web, (ii) discriminating dark energy models, and (iii) predicting galaxy colors. Our study substantiates a data-supported connection between cosmic web analysis and information theory, and paves the path towards principled design of analysis procedures for the next generation of galaxy surveys. We have made the cosmic web maps, galaxy catalog, and analysis scripts used in this work publicly available.

Comparing cosmic web classifiers using information theory

International Nuclear Information System (INIS)

Leclercq, Florent; Lavaux, Guilhem; Wandelt, Benjamin; Jasche, Jens

2016-01-01

We introduce a decision scheme for optimally choosing a classifier, which segments the cosmic web into different structure types (voids, sheets, filaments, and clusters). Our framework, based on information theory, accounts for the design aims of different classes of possible applications: (i) parameter inference, (ii) model selection, and (iii) prediction of new observations. As an illustration, we use cosmographic maps of web-types in the Sloan Digital Sky Survey to assess the relative performance of the classifiers T-WEB, DIVA and ORIGAMI for: (i) analyzing the morphology of the cosmic web, (ii) discriminating dark energy models, and (iii) predicting galaxy colors. Our study substantiates a data-supported connection between cosmic web analysis and information theory, and paves the path towards principled design of analysis procedures for the next generation of galaxy surveys. We have made the cosmic web maps, galaxy catalog, and analysis scripts used in this work publicly available.

Sheared Electroconvective Instability

Science.gov (United States)

Kwak, Rhokyun; Pham, Van Sang; Lim, Kiang Meng; Han, Jongyoon

2012-11-01

Recently, ion concentration polarization (ICP) and related phenomena draw attention from physicists, due to its importance in understanding electrochemical systems. Researchers have been actively studying, but the complexity of this multiscale, multiphysics phenomenon has been limitation for gaining a detailed picture. Here, we consider electroconvective(EC) instability initiated by ICP under pressure-driven flow, a scenario often found in electrochemical desalinations. Combining scaling analysis, experiment, and numerical modeling, we reveal unique behaviors of sheared EC: unidirectional vortex structures, its size selection and vortex propagation. Selected by balancing the external pressure gradient and the electric body force, which generates Hagen-Poiseuille(HP) flow and vortical EC, the dimensionless EC thickness scales as (φ2 /UHP)1/3. The pressure-driven flow(or shear) suppresses unfavorably-directed vortices, and simultaneously pushes favorably-directed vortices with constant speed, which is linearly proportional to the total shear of HP flow. This is the first systematic characterization of sheared EC, which has significant implications on the optimization of electrodialysis and other electrochemical systems.

Cosmic microwave background theory

Science.gov (United States)

Bond, J. Richard

1998-01-01

A long-standing goal of theorists has been to constrain cosmological parameters that define the structure formation theory from cosmic microwave background (CMB) anisotropy experiments and large-scale structure (LSS) observations. The status and future promise of this enterprise is described. Current band-powers in ℓ-space are consistent with a ΔT flat in frequency and broadly follow inflation-based expectations. That the levels are ∼(10−5)2 provides strong support for the gravitational instability theory, while the Far Infrared Absolute Spectrophotometer (FIRAS) constraints on energy injection rule out cosmic explosions as a dominant source of LSS. Band-powers at ℓ ≳ 100 suggest that the universe could not have re-ionized too early. To get the LSS of Cosmic Background Explorer (COBE)-normalized fluctuations right provides encouraging support that the initial fluctuation spectrum was not far off the scale invariant form that inflation models prefer: e.g., for tilted Λ cold dark matter sequences of fixed 13-Gyr age (with the Hubble constant H0 marginalized), ns = 1.17 ± 0.3 for Differential Microwave Radiometer (DMR) only; 1.15 ± 0.08 for DMR plus the SK95 experiment; 1.00 ± 0.04 for DMR plus all smaller angle experiments; 1.00 ± 0.05 when LSS constraints are included as well. The CMB alone currently gives weak constraints on Λ and moderate constraints on Ωtot, but theoretical forecasts of future long duration balloon and satellite experiments are shown which predict percent-level accuracy among a large fraction of the 10+ parameters characterizing the cosmic structure formation theory, at least if it is an inflation variant. PMID:9419321

Carl Sagan's Cosmic Connection

Science.gov (United States)

Sagan, Carl; Agel, Jerome

2000-08-01

Foreword Freeman Dyson; Personal reflections Ann Druyan; Preface; Part I. Cosmic Perspective: 1. A transitional animal; 2. The Unicorn of Cetus; 3. A message from earth; 4. A message to earth; 5. Experiments in utopias; 6. Chauvinism; 7. Space exploration as a human enterprise I. The scientific interest; 8. Space exploration as a human enterprise II. The public interest; 9. Space exploration as a human enterprise III. The historical interest; Part II. The Solar System: 10. On teaching the first grade; 11. 'The ancient and legendary Gods of old'; 12. The Venus detective story; 13. Venus is hell; 14. Science and 'intelligence'; 15. The moons of Barsoom; 16. The mountains of Mars I. Observations from earth; 17. The mountains of Mars II. Observations from space; 18. The canals of Mars; 19. The lost pictures of Mars; 20. The Ice Age and the cauldron; 21. Beginnings and ends of the Earth; 22. Terraforming the plants; 23. The exploration and utlization of the solar system; Part III. Beyond the Solar System: 24. Some of my best friends are dolphins; 25. 'Hello, central casting? Send me twenty extraterrestrials'; 26. The cosmic connection; 27. Extraterrestrial life: an idea whose time has come; 28. Has the Earth been visited?; 29. A search strategy for detecting extraterrestrial intelligence; 30. If we succeed 31. Cables, drums, and seashells; 32. The night freight to the stars; 33. Astroengineering; 34. Twenty questions: a classification of cosmic civilisations; 35. Galactic cultural exchanges; 36. A passage to elsewhere; 37. Starfolk I. A Fable; 38. Starfolk II. A future; 39. Starfolk III. The cosmic Cheshire cats; Epilog David Morrison; Index.

Isotherms clustering in cosmic microwave background

International Nuclear Information System (INIS)

Bershadskii, A.

2006-01-01

Isotherms clustering in cosmic microwave background (CMB) has been studied using the 3-year WMAP data on cosmic microwave background radiation. It is shown that the isotherms clustering could be produced by the baryon-photon fluid turbulence in the last scattering surface. The Taylor-microscale Reynolds number of the turbulence is estimated directly from the CMB data as Re λ ∼10 2

Fifty years of shear zones

Science.gov (United States)

Graham, Rodney

2017-04-01

We are here, of course, because 1967 saw the publication of John Ramsay's famous book. Two years later a memorable field trip from Imperial College to the Outer Hebrides saw John on a bleak headland on the coast of North Uist where a relatively undeformed metadolerite within Lewisian (Precambrian) gneisses contained ductile shear zones with metamorphic fabrics in amphibolite facies. One particular outcrop was very special - a shear zone cutting otherwise completely isotropic, undeformed metadolerite, with an incremental foliation starting to develop at 45° to the deformation zone, and increasing in intensity as it approached the shear direction. Here was proof of the process of simple shear under ductile metamorphic conditions - the principles of simple shear outlined in John Ramsay's 1967 book clearly visible in nature, and verified by Ramsay's mathematical proofs in the eventual paper (Ramsay and Graham, 1970). Later work on the Lewisian on the mainland of Scotland, in South Harris, in Africa, and elsewhere applied Ramsay's simple shear principles more liberally, more imprecisely and on larger scale than at Caisteal Odair, but in retrospect it documented what seems now to be the generality of mid and lower crustal deformation. Deep seismic reflection data show us that on passive margins hyper-stretched continental crust (whether or not cloaked by Seaward Dipping Reflectors) seems to have collapsed onto the mantle. Crustal faults mostly sole out at or above the mantle - so the Moho is a detachment- an 'outer marginal detachment', if you like, and, of course, it must be a ductile shear. On non-volcanic margins this shear zone forms the first formed ocean floor before true sea floor spreading gets going to create real oceanic crust. Gianreto Manatschal, Marcel Lemoine and others realised that the serpentinites described in parts of the Alps are exposed remnants of this ductile shear zone. Associated ophicalcite breccias tell of sea floor exposure, while high

High strength semi-active energy absorbers using shear- and mixedmode operation at high shear rates

Science.gov (United States)

Becnel, Andrew C.

This body of research expands the design space of semi-active energy absorbers for shock isolation and crash safety by investigating and characterizing magnetorheological fluids (MRFs) at high shear rates ( > 25,000 1/s) under shear and mixed-mode operation. Magnetorheological energy absorbers (MREAs) work well as adaptive isolators due to their ability to quickly and controllably adjust to changes in system mass or impact speed while providing fail-safe operation. However, typical linear stroking MREAs using pressure-driven flows have been shown to exhibit reduced controllability as impact speed (shear rate) increases. The objective of this work is to develop MREAs that improve controllability at high shear rates by using pure shear and mixed shear-squeeze modes of operation, and to present the fundamental theory and models of MR fluids under these conditions. A proof of concept instrument verified that the MR effect persists in shear mode devices at shear rates corresponding to low speed impacts. This instrument, a concentric cylinder Searle cell magnetorheometer, was then used to characterize three commercially available MRFs across a wide range of shear rates, applied magnetic fields, and temperatures. Characterization results are presented both as flow curves according to established practice, and as an alternate nondimensionalized analysis based on Mason number. The Mason number plots show that, with appropriate correction coefficients for operating temperature, the varied flow curve data can be collapsed to a single master curve. This work represents the first shear mode characterization of MRFs at shear rates over 10 times greater than available with commercial rheometers, as well as the first validation of Mason number analysis to high shear rate flows in MRFs. Using the results from the magnetorheometer, a full scale rotary vane MREA was developed as part of the Lightweight Magnetorheological Energy Absorber System (LMEAS) for an SH-60 Seahawk helicopter

Cosmic censorship, black holes, and particle orbits

International Nuclear Information System (INIS)

Hiscock, W.A.

1979-01-01

One of the main reasons for believing in the cosmic censorship hypothesis is the disquieting nature of the alternative: the existence of naked singularities, and hence loss of predictability, the possibility of closed timelike lines and so forth. The consequences of assuming the cosmic hypothesis can also be somewhat strange and unexpected. In particular, Hawking's black hole area theorem is applied to the study of particle orbits near a Schwarzschild black hole. If the cosmic censorship hypothesis (and hence the area theorem) is true, then there exist stable near-circular orbits arbitrarily close to the horizon at r = 2M. (author)

Cosmic-ray antimatter - A primary origin hypothesis

Science.gov (United States)

Stecker, F. W.; Protheroe, R. J.; Kazanas, D.

1983-01-01

The present investigation is concerned with the possibility that the observed cosmic-ray protons are of primary extragalactic origin, taking into account the significance of the current antiproton data. Attention is given to questions regarding primary antiprotons, antihelium fluxes, and the propagation of extragalactic cosmic rays. It is concluded that the primary origin hypothesis should be considered as a serious alternative explanation for the cosmic-ray antiproton fluxes. Such extragalactic primary origin can be considered in the context of a baryon symmetric domain cosmology. The fluxes and propagation characteristics suggested are found to be in rough agreement with the present antiproton data.

Wavelet-Bayesian inference of cosmic strings embedded in the cosmic microwave background

Science.gov (United States)

McEwen, J. D.; Feeney, S. M.; Peiris, H. V.; Wiaux, Y.; Ringeval, C.; Bouchet, F. R.

2017-12-01

Cosmic strings are a well-motivated extension to the standard cosmological model and could induce a subdominant component in the anisotropies of the cosmic microwave background (CMB), in addition to the standard inflationary component. The detection of strings, while observationally challenging, would provide a direct probe of physics at very high-energy scales. We develop a framework for cosmic string inference from observations of the CMB made over the celestial sphere, performing a Bayesian analysis in wavelet space where the string-induced CMB component has distinct statistical properties to the standard inflationary component. Our wavelet-Bayesian framework provides a principled approach to compute the posterior distribution of the string tension Gμ and the Bayesian evidence ratio comparing the string model to the standard inflationary model. Furthermore, we present a technique to recover an estimate of any string-induced CMB map embedded in observational data. Using Planck-like simulations, we demonstrate the application of our framework and evaluate its performance. The method is sensitive to Gμ ∼ 5 × 10-7 for Nambu-Goto string simulations that include an integrated Sachs-Wolfe contribution only and do not include any recombination effects, before any parameters of the analysis are optimized. The sensitivity of the method compares favourably with other techniques applied to the same simulations.

Cosmic strings in a braneworld theory with metastable gravitons

International Nuclear Information System (INIS)

Lue, Arthur

2002-01-01

If the graviton possesses an arbitrarily small (but nonvanishing) mass, perturbation theory implies that cosmic strings have a nonzero Newtonian potential. Nevertheless in Einstein gravity, where the graviton is strictly massless, the Newtonian potential of a cosmic string vanishes. This discrepancy is an example of the van Dam-Veltman-Zakharov (VDVZ) discontinuity. We present a solution for the metric around a cosmic string in a braneworld theory with a graviton metastable on the brane. This theory possesses those features that yield a VDVZ discontinuity in massive gravity, but nevertheless is generally covariant and classically self-consistent. Although the cosmic string in this theory supports a nontrivial Newtonian potential far from the source, one can recover the Einstein solution in a region near the cosmic string. That latter region grows as the graviton's effective linewidth vanishes (analogous to a vanishing graviton mass), suggesting the lack of a VDVZ discontinuity in this theory. Moreover, the presence of scale dependent structure in the metric may have consequences for the search for cosmic strings through gravitational lensing techniques

Current constraints on the cosmic growth history

International Nuclear Information System (INIS)

Bean, Rachel; Tangmatitham, Matipon

2010-01-01

We present constraints on the cosmic growth history with recent cosmological data, allowing for deviations from ΛCDM as might arise if cosmic acceleration is due to modifications to general relativity or inhomogeneous dark energy. We combine measures of the cosmic expansion history, from Type 1a supernovae, baryon acoustic oscillations, and the cosmic microwave background (CMB), with constraints on the growth of structure from recent galaxy, CMB, and weak lensing surveys along with integated Sachs Wolfe-galaxy cross correlations. Deviations from ΛCDM are parameterized by phenomenological modifications to the Poisson equation and the relationship between the two Newtonian potentials. We find modifications that are present at the time the CMB is formed are tightly constrained through their impact on the well-measured CMB acoustic peaks. By contrast, constraints on late-time modifications to the growth history, as might arise if modifications are related to the onset of cosmic acceleration, are far weaker, but remain consistent with ΛCDM at the 95% confidence level. For these late-time modifications we find that differences in the evolution on large and small scales could provide an interesting signature by which to search for modified growth histories with future wide angular coverage, large scale structure surveys.

Xenia: A Probe of Cosmic Chemical Evolution

Science.gov (United States)

Kouveliotou, Chryssa; Piro, L.

2008-01-01

Xenia is a concept study for a medium-size astrophysical cosmology mission addressing the Cosmic Origins key objective of NASA's Science Plan. The fundamental goal of this objective is to understand the formation and evolution of structures on various scales from the early Universe to the present time (stars, galaxies and the cosmic web). Xenia will use X-and y-ray monitoring and wide field X-ray imaging and high-resolution spectroscopy to collect essential information from three major tracers of these cosmic structures: the Warm Hot Intergalactic Medium (WHIM), Galaxy Clusters and Gamma Ray Bursts (GRBs). Our goal is to trace the chemo-dynamical history of the ubiquitous warm hot diffuse baryon component in the Universe residing in cosmic filaments and clusters of galaxies up to its formation epoch (at z =0-2) and to map star formation and galaxy metal enrichment into the re-ionization era beyond z 6. The concept of Xenia (Greek for "hospitality") evolved in parallel with the Explorer of Diffuse Emission and GRB Explosions (EDGE), a mission proposed by a multinational collaboration to the ESA Cosmic Vision 2015. Xenia incorporates the European and Japanese collaborators into a U.S. led mission that builds on the scientific objectives and technological readiness of EDGE.

Xenia: A Probe of Cosmic Chemical Evolution

Science.gov (United States)

Kouveliotou, Chryssa; Piro, L.; Xenia Collaboration

2008-03-01

Xenia is a concept study for a medium-size astrophysical cosmology mission addressing the Cosmic Origins key objective of NASA's Science Plan. The fundamental goal of this objective is to understand the formation and evolution of structures on various scales from the early Universe to the present time (stars, galaxies and the cosmic web). Xenia will use X-and γ-ray monitoring and wide field X-ray imaging and high-resolution spectroscopy to collect essential information from three major tracers of these cosmic structures: the Warm Hot Intergalactic Medium (WHIM), Galaxy Clusters and Gamma Ray Bursts (GRBs). Our goal is to trace the chemo-dynamical history of the ubiquitous warm hot diffuse baryon component in the Universe residing in cosmic filaments and clusters of galaxies up to its formation epoch (at z =0-2) and to map star formation and galaxy metal enrichment into the re-ionization era beyond z 6. The concept of Xenia (Greek for "hospitality") evolved in parallel with the Explorer of Diffuse Emission and GRB Explosions (EDGE), a mission proposed by a multinational collaboration to the ESA Cosmic Vision 2015. Xenia incorporates the European and Japanese collaborators into a U.S. led mission that builds on the scientific objectives and technological readiness of EDGE.

The Cosmic Ray Tracking (CRT) detector system

International Nuclear Information System (INIS)

Bernloehr, K.; Gamp, S.; Hermann, G.; Hofmann, W.; Kihm, T.; Knoeppler, J.; Leffers, G.; Matheis, V.; Panter, M.; Trunk, U.; Ulrich, M.; Wolf, T.; Zink, R.; Heintze, J.

1996-01-01

The Cosmic Ray Tracking (CRT) project represents a study on the use of tracking detectors of the time projection chamber type to detect secondary cosmic ray particles in extensive air showers. In reconstructing the arrival direction of the primary cosmic ray particles, the CRT detectors take advantage of the angular correlation of secondary particles with the cosmic rays leading to these air showers. In this paper, the detector hardware including the custom-designed electronics system is described in detail. A CRT detector module provides an active area of 2.5 m 2 and allows to measure track directions with a precision of 0.4 circle . It consists of two circular drift chambers of 1.8 m diameter with six sense wires each, and a 10 cm thick iron plate between the two chambers. Each detector has a local electronics box with a readout, trigger, and monitoring system. The detectors can distinguish penetrating muons from other types of charged secondaries. A large detector array could be used to search for γ-ray point sources at energies above several TeV and for studies of the cosmic-ray composition. Ten detectors are in operation at the site of the HEGRA air shower array. (orig.)

THE SLOAN DIGITAL SKY SURVEY CO-ADD: CROSS-CORRELATION WEAK LENSING AND TOMOGRAPHY OF GALAXY CLUSTERS

International Nuclear Information System (INIS)

Simet, Melanie; Dodelson, Scott; Kubo, Jeffrey M.; Annis, James T.; Hao Jiangang; Johnston, David; Lin, Huan; Soares-Santos, Marcelle; Reis, Ribamar R. R.; Seo, Hee-Jong

2012-01-01

The shapes of distant galaxies are sheared by intervening galaxy clusters. We examine this effect in Stripe 82, a 275 deg 2 region observed multiple times in the Sloan Digital Sky Survey (SDSS) and co-added to achieve greater depth. We obtain a mass-richness calibration that is similar to other SDSS analyses, demonstrating that the co-addition process did not adversely affect the lensing signal. We also propose a new parameterization of the effect of tomography on the cluster lensing signal which does not require binning in redshift, and we show that using this parameterization we can detect tomography for stacked clusters at varying redshifts. Finally, due to the sensitivity of the tomographic detection to accurately marginalize over the effect of the cluster mass, we show that tomography at low redshift (where dependence on exact cosmological models is weak) can be used to constrain mass profiles in clusters.

The Cosmic Microwave Background Anisotropy

Science.gov (United States)

Bennett, C. L.

1994-12-01

The properties of the cosmic microwave background radiation provide unique constraints on the history and evolution of the universe. The first detection of anisotropy of the microwave radiation was reported by the COBE Team in 1992, based on the first year of flight data. The latest analyses of the first two years of COBE data are reviewed in this talk, including the amplitude of the microwave anisotropy as a function of angular scale and the statistical nature of the fluctuations. The two-year results are generally consistent with the earlier first year results, but the additional data allow for a better determination of the key cosmological parameters. In this talk the COBE results are compared with other observational anisotropy results and directions for future cosmic microwave anisotropy observations will be discussed. The National Aeronautics and Space Administration/Goddard Space Flight Center (NASA/GSFC) is responsible for the design, development, and operation of the Cosmic Background Explorer (COBE). Scientific guidance is provided by the COBE Science Working Group.

Search for antimatter in 1012 eV cosmic rays using Artemis method and interpretation of the cosmic rays spectrum

International Nuclear Information System (INIS)

Pomarede, D.

1999-04-01

This thesis is divided into three parts. The first part is a review of the present knowledge of the antimatter and of the cosmic rays. Theoretical and experimental aspects are presented. It is demonstrated that a measurement of the antimatter abundance in TeV cosmic rays is of fundamental interest, and would establish the symmetric or asymmetric nature of the Universe. The second part is dedicated to the method of antimatter research through the Earth Moon ion spectrometer (ARTEMIS). The account is given of the winter 1996-97 41-nights observation campaign undertaken at the Whipple Observatory in Arizona (USA). A 109 photomultiplier camera is operated on the 40 meter telescope to detect by Cherenkov imaging the cosmic ray initiated showers. We describe the performance of an optical filter used to reduce the noise. The development and the utilization of a simulation program are described. The main work is the analysis of the data: data characterization, understanding of the apparatus, understanding of the noise and its influence, calibration, search for signals by different methods. Subtle systematic effects are uncovered. The simulations establish that the amount of data is insufficient to reveal a shadow effect in the cosmic ray flux. The conclusion of this work is that the experimental setup was not suitable, and we propose important improvements of the method based on a bigger focal plane that would allow to reach a one percent sensitivity on the antimatter content of the cosmic rays. In the third part of the thesis, an interpretation of the total cosmic ray spectrum is proposed and discussed. (author)

Cosmic-ray exposure records and origins of meteorites

International Nuclear Information System (INIS)

Reedy, R.C.

1985-01-01

The cosmic-ray records of meteorites are used to infer much about their origins and recent histories. The methods used to interpret meteorites cosmic-ray records, especially identifying simple or complex exposure histories, often are inadequate. Spallogenic radionuclides, stable nuclides, and measurements of products that have location-sensitive production rates, such as the tracks of heavy cosmic-ray nuclei or neutron-capture nuclides, are very useful in accurately determining a meteorite's history. Samples from different, known locations of a meteorite help in studying the cosmic-ray record. Such extensive sets of meteorite measuremetns, plus theoretical modeling of complex histories, improves the ability to predict the production of cosmogenic nuclides in meteorites, to distinguish simple and complex exposure histories, and to better determine exposure ages

A Piezoelectric Shear Stress Sensor

Science.gov (United States)

Kim, Taeyang; Saini, Aditya; Kim, Jinwook; Gopalarathnam, Ashok; Zhu, Yong; Palmieri, Frank L.; Wohl, Christopher J.; Jiang, Xiaoning

2016-01-01

In this paper, a piezoelectric sensor with a floating element was developed for shear stress measurement. The piezoelectric sensor was designed to detect the pure shear stress suppressing effects of normal stress generated from the vortex lift-up by applying opposite poling vectors to the: piezoelectric elements. The sensor was first calibrated in the lab by applying shear forces and it showed high sensitivity to shear stress (=91.3 +/- 2.1 pC/Pa) due to the high piezoelectric coefficients of PMN-33%PT (d31=-1330 pC/N). The sensor also showed almost no sensitivity to normal stress (less than 1.2 pC/Pa) because of the electromechanical symmetry of the device. The usable frequency range of the sensor is 0-800 Hz. Keywords: Piezoelectric sensor, shear stress, floating element, electromechanical symmetry

Interstellar propagation of low energy cosmic rays

International Nuclear Information System (INIS)

Cesarsky, C.J.

1975-01-01

Wave particles interactions prevent low energy cosmic rays from propagating at velocities much faster than the Alfven velocity, reducing their range by a factor of order 50. Therefore, supernovae remnants cannot fill the neutral portions of the interstellar medium with 2 MeV cosmic rays [fr

The dynamics of a shear band

Science.gov (United States)

Giarola, Diana; Capuani, Domenico; Bigoni, Davide

2018-03-01

A shear band of finite length, formed inside a ductile material at a certain stage of a continued homogeneous strain, provides a dynamic perturbation to an incident wave field, which strongly influences the dynamics of the material and affects its path to failure. The investigation of this perturbation is presented for a ductile metal, with reference to the incremental mechanics of a material obeying the J2-deformation theory of plasticity (a special form of prestressed, elastic, anisotropic, and incompressible solid). The treatment originates from the derivation of integral representations relating the incremental mechanical fields at every point of the medium to the incremental displacement jump across the shear band faces, generated by an impinging wave. The boundary integral equations (under the plane strain assumption) are numerically approached through a collocation technique, which keeps into account the singularity at the shear band tips and permits the analysis of an incident wave impinging a shear band. It is shown that the presence of the shear band induces a resonance, visible in the incremental displacement field and in the stress intensity factor at the shear band tips, which promotes shear band growth. Moreover, the waves scattered by the shear band are shown to generate a fine texture of vibrations, parallel to the shear band line and propagating at a long distance from it, but leaving a sort of conical shadow zone, which emanates from the tips of the shear band.

Cosmic radiation doses at flight level altitudes of airliners

International Nuclear Information System (INIS)

Viragh, E.; Petr, I.

1985-01-01

Changes are discussed in flux density of cosmic radiation particles with time as are the origin of cosmic radiation, the level of cosmic radiation near the Earth's surface, and the determination of cosmic radiation doses in airliners. Doses and dose rates are given measured on different flight routes. In spite of the fact that the flight duration at an altitude of about 10 km makes for about 80% of the total flight time, the overall radiation burden of the crews at 1000 flight hours a year is roughly double that of the rest of the population. (J.C.)

Simulations of Granular Particles Under Cyclic Shear

Science.gov (United States)

Royer, John; Chaikin, Paul

2012-02-01

We perform molecular dynamics (MD) simulations of spherical grains subjected to cyclic, quasi-static shear in a 3D parallelepiped shear cell. This virtual shear cell is constructed out of rough, bumpy walls in order to minimize wall-induced ordering and has an open top surface to allow the packing to readily dilate or compact. Using a standard routine for MD simulations of frictional grains, we simulate over 1000 shear cycles, measuring grain displacements, the local packing density and changes in the contact network. Varying the shear amplitude and the friction coefficient between grains, we map out a phase diagram for the different types of behavior exhibited by these sheared grains. With low friction and high enough shear, the grains can spontaneously order into densely packed crystals. With low shear and increasing friction the packing remains disordered, yet the grains arrange themselves into configurations which exhibit limit cycles where all grains return to the same position after each full shear cycle. At higher shear and friction there is a transition to a diffusive state, where grains continue rearrange and move throughout the shear cell.

Standard Cosmic Ray Energetics and Light Element Production

CERN Document Server

Fields, B D; Cassé, M; Vangioni-Flam, E; Fields, Brian D.; Olive, Keith A.; Casse, Michel; Vangioni-Flam, Elisabeth

2001-01-01

The recent observations of Be and B in metal poor stars has led to a reassessment of the origin of the light elements in the early Galaxy. At low it is metallicity ([O/H] < -1.75), it is necessary to introduce a production mechanism which is independent of the interstellar metallicity (primary). At higher metallicities, existing data might indicate that secondary production is dominant. In this paper, we focus on the secondary process, related to the standard Galactic cosmic rays, and we examine the cosmic ray energy requirements for both present and past epochs. We find the power input to maintain the present-day Galactic cosmic ray flux is about 1.5e41 erg/s = 5e50 erg/century. This implies that, if supernovae are the sites of cosmic ray acceleration, the fraction of explosion energy going to accelerated particles is about 30%, a value which we obtain consistently both from considering the present cosmic ray flux and confinement and from the present 9Be and 6Li abundances. Using the abundances of 9Be (an...

Relative distribution of cosmic rays and magnetic fields

Science.gov (United States)

Seta, Amit; Shukurov, Anvar; Wood, Toby S.; Bushby, Paul J.; Snodin, Andrew P.

2018-02-01

Synchrotron radiation from cosmic rays is a key observational probe of the galactic magnetic field. Interpreting synchrotron emission data requires knowledge of the cosmic ray number density, which is often assumed to be in energy equipartition (or otherwise tightly correlated) with the magnetic field energy. However, there is no compelling observational or theoretical reason to expect such a tight correlation to hold across all scales. We use test particle simulations, tracing the propagation of charged particles (protons) through a random magnetic field, to study the cosmic ray distribution at scales comparable to the correlation scale of the turbulent flow in the interstellar medium (≃100 pc in spiral galaxies). In these simulations, we find that there is no spatial correlation between the cosmic ray number density and the magnetic field energy density. In fact, their distributions are approximately statistically independent. We find that low-energy cosmic rays can become trapped between magnetic mirrors, whose location depends more on the structure of the field lines than on the field strength.

A Prototype Large Area Detector Module for Muon Scattering Tomography

Energy Technology Data Exchange (ETDEWEB)

Steer, C.A.; Boakes, J.; Burns, J.; Snow, S.; Stapleton, M.; Thompson, L.F.; Quillin, S. [AWE Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom)

2015-07-01

Abstract-Shielded special nuclear materials (SNM) are of concern as some fissile isotopes have low gamma and neutron emission rates. These materials are also easily shielded to the point where their passive emissions are comparable to background. Consequently, shielded SNM is very challenging for passive radiation detection portals which scan cargo containers. One potential solution for this is to utilise the natural cosmic ray muon background and examine how these muons scatter from materials inside the container volume, terms; the muon scattering tomography (MST) technique measures the three-dimensional localised scattering at all points within a cargo container, providing a degree of material discrimination. There is the additional benefit that the MST signal increases with the presence of more high density shielding materials, in contrast to passive radiation detection. Simulations and calculations suggest that the effectiveness of the technique is sensitive to the tracking accuracy amongst other parameters, motivating the need to develop practical detector systems that are capable of tracking cosmic ray muons. To this end, we have constructed and tested a 2 m by 2 m demonstration module based on gaseous drift chambers and triggered by a large area scintillator-based detector, which is readout by wavelength shifting fibres. We discuss its design, construction, characterisation and operational challenges. (authors)

George Smoot, Blackbody, and Anisotropy of the Cosmic Microwave Background

Science.gov (United States)

the Cosmic Microwave Background Radiation Resources with Additional Information * Videos 'George Smoot anisotropy of the cosmic microwave background radiation." '1 Smoot previously won the Ernest Orlando . Smoot, blackbody, and anisotropy of the Cosmic Microwave Background (CMB) radiation is available in full

Cosmic Rays Astrophysics: The Discipline, Its Scope, and Its Applications

Science.gov (United States)

Barghouty, A. F.

2009-01-01

This slide presentation gives an overview of the discipline surrounding cosmic ray astrophysics. It includes information on recent assertions surrounding cosmic rays, exposure levels, and a short history with specific information on the origin, acceleration, transport, and modulation of cosmic rays.

Constraints on early dark energy from CMB lensing and weak lensing tomography

International Nuclear Information System (INIS)

Hollenstein, Lukas; Crittenden, Robert; Sapone, Domenico; Schäfer, Björn Malte

2009-01-01

Dark energy can be studied by its influence on the expansion of the Universe as well as on the growth history of the large-scale structure. In this paper, we follow the growth of the cosmic density field in early dark energy cosmologies by combining observations of the primary CMB temperature and polarisation power spectra at high redshift, of the CMB lensing deflection field at intermediate redshift and of weak cosmic shear at low redshifts for constraining the allowed amount of early dark energy. We present these forecasts using the Fisher matrix formalism and consider the combination of Planck data with the weak lensing survey of Euclid. We find that combining these data sets gives powerful constraints on early dark energy and is able to break degeneracies in the parameter set inherent to the various observational channels. The derived statistical 1σ-bound on the early dark energy density parameter is σ(Ω e d ) = 0.0022 which suggests that early dark energy models can be well examined in our approach. In addition, we derive the dark energy figure of merit for the considered dark energy parameterisation and comment on the applicability of the growth index to early dark energy cosmologies

Theory of geomagnetic effects of cosmic rays: its past and presence

Energy Technology Data Exchange (ETDEWEB)

Gall, R [Universidad Nacional Autonoma de Mexico, Mexico City. Inst. de Geofisica

1981-03-01

The interest expressed by Lemaitre and Vallarta in the nature of universal corpuscular radiation, remnant of the exploded primogenitive atom, culminated in 1932, in the development of their theory of the geomagnetic effects of cosmic rays, a tool since its publication, basic to cosmic radiation research and to the advancement of cosmic ray astronomy. Between 1940 and 1960 challenging experimental data from proliferating cosmic radiation stations and of direct detection techniques provided geomagnetic field models for greater theoretical precision. The discoveries since the advent of the space age of the Earth's cavity and geomagnetic tail, and of the nonrelativistic solar cosmic rays have resulted in a new branch of the theory dealing with magnetosphere effects in the propagation of low energy cosmic radiations. The theory's importance and application to cosmic bodies other than the Earth is discussed.

Cosmic Dawn with WFIRST

Science.gov (United States)

Rhoads, James

Central objectives: WFIRST-AFTA has tremendous potential for studying the epoch of "Cosmic Dawn" the period encompassing the formation of the first galaxies and quasars, and their impact on the surrounding universe through cosmological reionization. Our goal is to ensure that this potential is realized through the middle stages of mission planning, culminating in designs for both WFIRST and its core surveys that meet the core objectives in dark energy and exoplanet science, while maximizing the complementary Cosmic Dawn science. Methods: We will consider a combined approach to studying Cosmic Dawn using a judicious mixture of guest investigator data analysis of the primary WFIRST surveys, and a specifically designed Guest Observer program to complement those surveys. The Guest Observer program will serve primarily to obtain deep field observations, with particular attention to the capabilities of WFIRST for spectroscopic deep fields using the WFI grism. We will bring to bear our years of experience with slitless spectroscopy on the Hubble Space Telescope, along with an expectation of JWST slitless grism spectroscopy. We will use this experience to examine the implications of WFIRST’s grism resolution and wavelength coverage for deep field observations, and if appropriate, to suggest potential modifications of these parameters to optimize the science return on WFIRST. We have assembled a team of experts specializing in (1) Lyman Break Galaxies at redshifts higher than 7 (2) Quasars at high redshifts (3) Lyman-alpha galaxies as probes of reionization (4) Theoretical simulations of high-redshift galaxies (5) Simulations of grism observations (6) post-processing analysis to find emission line galaxies and high redshift galaxies (7) JWST observations and calibrations. With this team we intend to do end-to-end simulations starting with halo populations and expected spectra of high redshift galaxies and finally extracting what we can learn about (a) reionization

Simulation of a small muon tomography station system based on RPCs

Science.gov (United States)

Chen, S.; Li, Q.; Ma, J.; Kong, H.; Ye, Y.; Gao, J.; Jiang, Y.

2014-10-01

In this work, Monte Carlo simulations were used to study the performance of a small muon Tomography Station based on four glass resistive plate chambers(RPCs) with a spatial resolution of approximately 1.0mm (FWHM). We developed a simulation code to generate cosmic ray muons with the appropriate distribution of energies and angles. PoCA and EM algorithm were used to rebuild the objects for comparison. We compared Z discrimination time with and without muon momentum measurement. The relation between Z discrimination time and spatial resolution was also studied. Simulation results suggest that mean scattering angle is a better Z indicator and upgrading to larger RPCs will improve reconstruction image quality.

Th/U/Pu/Cm dating of galactic cosmic rays with the extremely heavy cosmic ray composition observer

Science.gov (United States)

Westphal, Andrew J.; Weaver, Benjamin A.; Tarlé, Gregory

The principal goal of ECCO, the Extremely-heavy Cosmic-ray Composition Observer, is the measurement of the age of heavy galactic cosmic-ray nuclei using the extremely rare actinides (Th, U, Pu, Cm) as clocks. ECCO is one of two cosmic-ray instruments comprising the Heavy Nuclei Explorer (HNX), which was recently selected as one of several missions for Phase A study under NASA's Small class Explorer (SMEX) program. ECCO is based on the flight heritage of Trek, an array of barium-phosphate glass tracketch detectors deployed on the Russian space station Mir from 1991-1995. Using Trek, we measured the abundances of elements with Z > 70 in the galactic cosmic rays (GCRs). Trek consisted of a 1 m 2 array of stacks of individually polished thin BP-1 glass detectors. ECCO will be a much larger instrument, but will achieve both excellent resolution and low cost through use of a novel detector configuration. Here we report the results of recent accelerator tests of the ECCO detectors that verify detector performance. We also show the expected charge and energy resolution of ECCO as a function of energy.

Measurement of cosmic-ray reconstruction efficiencies in the MicroBooNE LArTPC using a small external cosmic-ray counter

Science.gov (United States)

Acciarri, R.; Adams, C.; An, R.; Anthony, J.; Asaadi, J.; Auger, M.; Bagby, L.; Balasubramanian, S.; Baller, B.; Barnes, C.; Barr, G.; Bass, M.; Bay, F.; Bishai, M.; Blake, A.; Bolton, T.; Camilleri, L.; Caratelli, D.; Carls, B.; Castillo Fernandez, R.; Cavanna, F.; Chen, H.; Church, E.; Cianci, D.; Cohen, E.; Collin, G. H.; Conrad, J. M.; Convery, M.; Crespo-Anadón, J. I.; Del Tutto, M.; Devitt, D.; Dytman, S.; Eberly, B.; Ereditato, A.; Escudero Sanchez, L.; Esquivel, J.; Fadeeva, A. A.; Fleming, B. T.; Foreman, W.; Furmanski, A. P.; Garcia-Gamez, D.; Garvey, G. T.; Genty, V.; Goeldi, D.; Gollapinni, S.; Graf, N.; Gramellini, E.; Greenlee, H.; Grosso, R.; Guenette, R.; Hackenburg, A.; Hamilton, P.; Hen, O.; Hewes, J.; Hill, C.; Ho, J.; Horton-Smith, G.; Hourlier, A.; Huang, E.-C.; James, C.; de Vries, J. Jan; Jen, C.-M.; Jiang, L.; Johnson, R. A.; Joshi, J.; Jostlein, H.; Kaleko, D.; Kalousis, L. N.; Karagiorgi, G.; Ketchum, W.; Kirby, B.; Kirby, M.; Kobilarcik, T.; Kreslo, I.; Lange, G.; Laube, A.; Li, Y.; Lister, A.; Littlejohn, B. R.; Lockwitz, S.; Lorca, D.; Louis, W. C.; Luethi, M.; Lundberg, B.; Luo, X.; Marchionni, A.; Mariani, C.; Marshall, J.; Martinez Caicedo, D. A.; Meddage, V.; Miceli, T.; Mills, G. B.; Moon, J.; Mooney, M.; Moore, C. D.; Mousseau, J.; Murrells, R.; Naples, D.; Nienaber, P.; Nowak, J.; Palamara, O.; Paolone, V.; Papavassiliou, V.; Pate, S. F.; Pavlovic, Z.; Pelkey, R.; Piasetzky, E.; Porzio, D.; Pulliam, G.; Qian, X.; Raaf, J. L.; Rafique, A.; Rochester, L.; von Rohr, C. Rudolf; Russell, B.; Schmitz, D. W.; Schukraft, A.; Seligman, W.; Shaevitz, M. H.; Sinclair, J.; Smith, A.; Snider, E. L.; Soderberg, M.; Söldner-Rembold, S.; Soleti, S. R.; Spentzouris, P.; Spitz, J.; John, J. St.; Strauss, T.; Szelc, A. M.; Tagg, N.; Terao, K.; Thomson, M.; Toups, M.; Tsai, Y.-T.; Tufanli, S.; Usher, T.; Van De Pontseele, W.; Van de Water, R. G.; Viren, B.; Weber, M.; Wickremasinghe, D. A.; Wolbers, S.; Wongjirad, T.; Woodruff, K.; Yang, T.; Yates, L.; Zeller, G. P.; Zennamo, J.; Zhang, C.

2017-12-01

The MicroBooNE detector is a liquid argon time projection chamber at Fermilab designed to study short-baseline neutrino oscillations and neutrino-argon interaction cross-section. Due to its location near the surface, a good understanding of cosmic muons as a source of backgrounds is of fundamental importance for the experiment. We present a method of using an external 0.5 m (L) × 0.5 m (W) muon counter stack, installed above the main detector, to determine the cosmic-ray reconstruction efficiency in MicroBooNE. Data are acquired with this external muon counter stack placed in three different positions, corresponding to cosmic rays intersecting different parts of the detector. The data reconstruction efficiency of tracks in the detector is found to be epsilondata=(97.1±0.1 (stat) ± 1.4 (sys))%, in good agreement with the Monte Carlo reconstruction efficiency epsilonMC = (97.4±0.1)%. This analysis represents a small-scale demonstration of the method that can be used with future data coming from a recently installed cosmic-ray tagger system, which will be able to tag ≈80% of the cosmic rays passing through the MicroBooNE detector.

CAT LIDAR wind shear studies

Science.gov (United States)

Goff, R. W.

1978-01-01

The studies considered the major meteorological factors producing wind shear, methods to define and classify wind shear in terms significant from an aircraft perturbation standpoint, the significance of sensor location and scan geometry on the detection and measurement of wind shear, and the tradeoffs involved in sensor performance such as range/velocity resolution, update frequency and data averaging interval.

Cosmic ray electrons and protons, and their antiparticles

International Nuclear Information System (INIS)

Boezio, Mirko

2014-01-01

Cosmic rays are a sample of solar, galactic, and extragalactic matter. Their origin, acceleration mechanisms, and subsequent propagation toward Earth have intrigued scientists since their discovery. These issues can be studied via analysis of the energy spectra and composition of cosmic rays. Protons are the most abundant component of the cosmic radiation, and many experiments have been dedicated to the accurate measurement of their spectra. Complementary information is provided by electrons, which comprise about 1% of the cosmic radiation. Because of their low mass, electrons experience severe energy losses through synchrotron emission in the galactic magnetic field and inverse Compton scattering of radiation fields. Electrons therefore provide information on the local galactic environment that is not accessible from the study of the cosmic ray nuclei. Antiparticles, namely antiprotons and positrons, are produced in the interaction between cosmic ray nuclei and the interstellar matter. They are therefore intimately linked to the propagation mechanisms of the parent nuclei. Novel sources of primary cosmic ray antiparticles of either astrophysical (e.g., positrons from pulsars) or exotic origin (e.g., annihilation of dark matter particles) may exist. The nature of dark matter is one of the most prominent open questions in science today. An observation of positrons from pulsars would open a new observation window on these sources. Several experiments equipped with state-of-the art detector systems have recently presented results on the energy spectra of electrons, protons, and their antiparticles with a significant improvement in statistics and better control of systematics The status of the field will be reviewed, with a focus on these recent scientific results. (author)

Radar detection of ultra high energy cosmic rays

Science.gov (United States)

Myers, Isaac J.

TARA (Telescope Array Radar) is a cosmic ray radar detection experiment co-located with Telescope Array, the conventional surface scintillation detector (SD) and fluorescence telescope detector (FD) near Delta, UT. The TARA detector combines a 40 kW transmitter and high gain transmitting antenna which broadcasts the radar carrier over the SD array and in the FD field of view to a 250 MS/s DAQ receiver. Data collection began in August, 2013. TARA stands apart from other cosmic ray radar experiments in that radar data is directly compared with conventional cosmic ray detector events. The transmitter is also directly controlled by TARA researchers. Waveforms from the FD-triggered data stream are time-matched with TA events and searched for signal using a novel signal search technique in which the expected (simulated) radar echo of a particular air shower is used as a matched filter template and compared to radio waveforms. This technique is used to calculate the radar cross-section (RCS) upper-limit on all triggers that correspond to well-reconstructed TA FD monocular events. Our lowest cosmic ray RCS upper-limit is 42 cm2 for an 11 EeV event. An introduction to cosmic rays is presented with the evolution of detection and the necessity of new detection techniques, of which radar detection is a candidate. The software simulation of radar scattering from cosmic rays follows. The TARA detector, including transmitter and receiver systems, are discussed in detail. Our search algorithm and methodology for calculating RCS is presented for the purpose of being repeatable. Search results are explained in context of the usefulness and future of cosmic ray radar detection.

Anomalous isotopic composition of cosmic rays

International Nuclear Information System (INIS)

Woosley, S.E.; Weaver, T.A.

1980-01-01

Recent measurements of nonsolar isotopic patterns for the elements neon and (perhaps) magnesium in cosmic rays are interpreted within current models of stellar nucleosynthesis. One possible explanation is that the stars currently responsible for cosmic-ray synthesis in the Galaxy are typically super-metal-rich by a factor of two to three. Other possibilities include the selective acceleration of certain zones or masses of supernovas or the enhancement of 22 Ne in the interstellar medium by mass loss from red giant stars and planetary nebulas. Measurements of critical isotopic ratios are suggested to aid in distinguishing among the various possibilities. Some of these explanations place significant constraints on the fraction of cosmic ray nuclei that must be fresh supernova debris and the masses of the supernovas involved. 1 figure, 3 tables

Cosmic microwave background bispectrum from recombination.

Science.gov (United States)

Huang, Zhiqi; Vernizzi, Filippo

2013-03-08

We compute the cosmic microwave background temperature bispectrum generated by nonlinearities at recombination on all scales. We use CosmoLib2nd, a numerical Boltzmann code at second order to compute cosmic microwave background bispectra on the full sky. We consistently include all effects except gravitational lensing, which can be added to our result using standard methods. The bispectrum is peaked on squeezed triangles and agrees with the analytic approximation in the squeezed limit at the few percent level for all the scales where this is applicable. On smaller scales, we recover previous results on perturbed recombination. For cosmic-variance limited data to l(max)=2000, its signal-to-noise ratio is S/N=0.47, corresponding to f(NL)(eff)=-2.79, and will bias a local signal by f(NL)(loc) ~/= 0.82.

The propagation of galactic cosmic rays

International Nuclear Information System (INIS)

Hall, A.N.

1981-01-01

Large scale (approximately 15 pc) turbulence in the interstellar medium (ISM) causes the firehose and mirror instabilities to occur. These produce small scale (approximately 10 -7 pc) magnetic irregularities, which scatter cosmic rays. We use pulsar scintillation data, and a model of the origin of these scintillations, to construct a slab model of the turbulent ISM. Then we find the amplitudes and wavelengths of the magnetic irregularities that arise, and we calculate the coefficients for the diffusion of cosmic rays along the interstellar magnetic fields. We incorporate this diffusion into our model of the turbulent ISM, and show that it can account naturally for both the lifetime of low energy cosmic rays, and the variation of their mean pathlength with energy. Our model has no galactic halo, and contains no scattering by Alfven waves. (author)

Cosmic-ray modulation: an ab initio approach

Energy Technology Data Exchange (ETDEWEB)

Engelbrecht, N.E.; Burger, R.A., E-mail: 12580996@nwu.ac.za [Center for Space Research, North-West University, Potchefstroom (South Africa)

2014-07-01

A better understanding of cosmic-ray modulation in the heliosphere can only be gained through a proper understanding of the effects of turbulence on the diffusion and drift of cosmic rays. We present an ab initio model for cosmic-ray modulation, incorporating for the first time the results yielded by a two-component turbulence transport model. This model is solved for periods of minimum solar activity, utilizing boundary values chosen so that model results are in fair to good agreement with spacecraft observations of turbulence quantities, not only in the solar ecliptic plane but also along the out-of-ecliptic trajectory of the Ulysses spacecraft. These results are employed as inputs for modelled slab and 2D turbulence energy spectra. The latter spectrum is chosen based on physical considerations, with a drop-off at the very lowest wavenumbers commencing at the 2D outerscale. There currently exist no models or observations for this quantity, and it is the only free parameter in this study. The modelled turbulence spectra are used as inputs for parallel mean free path expressions based on those derived from quasi-linear theory and perpendicular mean free paths from extended nonlinear guiding center theory. Furthermore, the effects of turbulence on cosmic-ray drifts are modelled in a self-consistent way, employing a recently developed model for drift along the wavy current sheet. The resulting diffusion coefficients and drift expressions are applied to the study of galactic cosmic-ray protons and antiprotons using a three dimensional, steady-state cosmic-ray modulation code, and sample solutions in fair agreement with multiple spacecraft observations are presented. (author)

Cosmic-ray modulation: an ab initio approach

International Nuclear Information System (INIS)

Engelbrecht, N.E.; Burger, R.A.

2014-01-01

A better understanding of cosmic-ray modulation in the heliosphere can only be gained through a proper understanding of the effects of turbulence on the diffusion and drift of cosmic rays. We present an ab initio model for cosmic-ray modulation, incorporating for the first time the results yielded by a two-component turbulence transport model. This model is solved for periods of minimum solar activity, utilizing boundary values chosen so that model results are in fair to good agreement with spacecraft observations of turbulence quantities, not only in the solar ecliptic plane but also along the out-of-ecliptic trajectory of the Ulysses spacecraft. These results are employed as inputs for modelled slab and 2D turbulence energy spectra. The latter spectrum is chosen based on physical considerations, with a drop-off at the very lowest wavenumbers commencing at the 2D outerscale. There currently exist no models or observations for this quantity, and it is the only free parameter in this study. The modelled turbulence spectra are used as inputs for parallel mean free path expressions based on those derived from quasi-linear theory and perpendicular mean free paths from extended nonlinear guiding center theory. Furthermore, the effects of turbulence on cosmic-ray drifts are modelled in a self-consistent way, employing a recently developed model for drift along the wavy current sheet. The resulting diffusion coefficients and drift expressions are applied to the study of galactic cosmic-ray protons and antiprotons using a three dimensional, steady-state cosmic-ray modulation code, and sample solutions in fair agreement with multiple spacecraft observations are presented. (author)

The basis for cosmic ray feedback: Written on the wind

Science.gov (United States)

Zweibel, Ellen G.

2017-05-01

Star formation and supermassive black hole growth in galaxies appear to be self-limiting. The mechanisms for self-regulation are known as feedback. Cosmic rays, the relativistic particle component of interstellar and intergalactic plasma, are among the agents of feedback. Because cosmic rays are virtually collisionless in the plasma environments of interest, their interaction with the ambient medium is primarily mediated by large scale magnetic fields and kinetic scale plasma waves. Because kinetic scales are much smaller than global scales, this interaction is most conveniently described by fluid models. In this paper, I discuss the kinetic theory and the classical theory of cosmic ray hydrodynamics (CCRH) which follows from assuming cosmic rays interact only with self-excited waves. I generalize CCRH to generalized cosmic ray hydrodynamics, which accommodates interactions with extrinsic turbulence, present examples of cosmic ray feedback, and assess where progress is needed.

ATLAS and ultra high energy cosmic ray physics

Directory of Open Access Journals (Sweden)

Pinfold James

2017-01-01

Full Text Available After a brief introduction to extended air shower cosmic ray physics the current and future deployment of forward detectors at ATLAS is discussed along with the various aspects of the current and future ATLAS programs to explore hadronic physics. The emphasis is placed on those results and future plans that have particular relevance for high-energy, and ultra high-energy, cosmic ray physics. The possible use of ATLAS as an “underground” cosmic muon observatory is briefly considered.

Ambient noise adjoint tomography for a linear array in North China

Science.gov (United States)

Zhang, C.; Yao, H.; Liu, Q.; Yuan, Y. O.; Zhang, P.; Feng, J.; Fang, L.

2017-12-01

Ambient noise tomography based on dispersion data and ray theory has been widely utilized for imaging crustal structures. In order to improve the inversion accuracy, ambient noise tomography based on the 3D adjoint approach or full waveform inversion has been developed recently, however, the computational cost is tremendous. In this study we present 2D ambient noise adjoint tomography for a linear array in north China with significant computational efficiency compared to 3D ambient noise adjoint tomography. During the preprocessing, we first convert the observed data in 3D media, i.e., surface-wave empirical Green's functions (EGFs) from ambient noise cross-correlation, to the reconstructed EGFs in 2D media using a 3D/2D transformation scheme. Different from the conventional steps of measuring phase dispersion, the 2D adjoint tomography refines 2D shear wave speeds along the profile directly from the reconstructed Rayleigh wave EGFs in the period band 6-35s. With the 2D initial model extracted from the 3D model from traditional ambient noise tomography, adjoint tomography updates the model by minimizing the frequency-dependent Rayleigh wave traveltime misfits between the reconstructed EGFs and synthetic Green function (SGFs) in 2D media generated by the spectral-element method (SEM), with a preconditioned conjugate gradient method. The multitaper traveltime difference measurement is applied in four period bands during the inversion: 20-35s, 15-30s, 10-20s and 6-15s. The recovered model shows more detailed crustal structures with pronounced low velocity anomaly in the mid-lower crust beneath the junction of Taihang Mountains and Yin-Yan Mountains compared with the initial model. This low velocity structure may imply the possible intense crust-mantle interactions, probably associated with the magmatic underplating during the Mesozoic to Cenozoic evolution of the region. To our knowledge, it's first time that ambient noise adjoint tomography is implemented in 2D media

Shear flow effect on ion temperature gradient vortices in plasmas with sheared magnetic field

DEFF Research Database (Denmark)

Chakrabarti, N.; Juul Rasmussen, J.

1999-01-01

The effect of velocity shear on ion temperature gradient (ITG) driven vortices in a nonuniform plasma in a curved, sheared magnetic field is investigated. In absence of parallel ion dynamics, vortex solutions for the ITG mode are studied analytically. It is shown that under certain conditions...... and ultimately lead to a dominating monopolar form. The effects of magnetic shear indicate it may destroy these structures. (C) 1999 American Institute of Physics....

Delayed recombination and cosmic parameters

International Nuclear Information System (INIS)

Galli, Silvia; Melchiorri, Alessandro; Bean, Rachel; Silk, Joseph

2008-01-01

Current cosmological constraints from cosmic microwave background anisotropies are typically derived assuming a standard recombination scheme, however additional resonance and ionizing radiation sources can delay recombination, altering the cosmic ionization history and the cosmological inferences drawn from the cosmic microwave background data. We show that for recent observations of the cosmic microwave background anisotropy, from the Wilkinson microwave anisotropy probe satellite mission (WMAP) 5-year survey and from the arcminute cosmology bolometer array receiver experiment, additional resonance radiation is nearly degenerate with variations in the spectral index, n s , and has a marked effect on uncertainties in constraints on the Hubble constant, age of the universe, curvature and the upper bound on the neutrino mass. When a modified recombination scheme is considered, the redshift of recombination is constrained to z * =1078±11, with uncertainties in the measurement weaker by 1 order of magnitude than those obtained under the assumption of standard recombination while constraints on the shift parameter are shifted by 1σ to R=1.734±0.028. From the WMAP5 data we obtain the following constraints on the resonance and ionization sources parameters: ε α i <0.058 at 95% c.l.. Although delayed recombination limits the precision of parameter estimation from the WMAP satellite, we demonstrate that this should not be the case for future, smaller angular scales measurements, such as those by the Planck satellite mission.

Gamma-ray astronomy and cosmic-ray origin theory

International Nuclear Information System (INIS)

Ginzburg, V.L.

1973-01-01

A theory of the origin of cosmic radiation is discussed in light of the advances made in gamma-ray astronomy. Arguments against metagalactic models for the origin of cosmic rays are emphasized. (U.S.)

Friction of Shear-Fracture Zones

Science.gov (United States)

Riikilä, T. I.; Pylväinen, J. I.; Åström, J.

2017-12-01

A shear fracture of brittle solids under compression undergoes a substantial evolution from the initial microcracking to a fully formed powder-filled shear zone. Experiments covering the entire process are relatively easy to conduct, but they are very difficult to investigate in detail. Numerically, the large strain limit has remained a challenge. An efficient simulation model and a custom-made experimental device are employed to test to what extent a shear fracture alone is sufficient to drive material to spontaneous self-lubrication. A "weak shear zone" is an important concept in geology, and a large number of explanations, specific for tectonic conditions, have been proposed. We demonstrate here that weak shear zones are far more general, and that their emergence only demands that a microscopic, i.e., fragment-scale, stress relaxation mechanism develops during the fracture process.

Cosmic Rays in Thunderstorms

Science.gov (United States)

Buitink, Stijn; Scholten, Olaf; van den Berg, Ad; Ebert, Ute

2013-04-01

Cosmic Rays in Thunderstorms Cosmic rays are protons and heavier nuclei that constantly bombard the Earth's atmosphere with energies spanning a vast range from 109 to 1021 eV. At typical altitudes up to 10-20 km they initiate large particle cascades, called extensive air showers, that contain millions to billions of secondary particles depending on their initial energy. These particles include electrons, positrons, hadrons and muons, and are concentrated in a compact particle front that propagates at relativistic speed. In addition, the shower leaves behind a trail of lower energy electrons from ionization of air molecules. Under thunderstorm conditions these electrons contribute to the electrical and ionization processes in the cloud. When the local electric field is strong enough the secondary electrons can create relativistic electron run-away avalanches [1] or even non-relativistic avalanches. Cosmic rays could even trigger lightning inception. Conversely, strong electric fields also influence the development of the air shower [2]. Extensive air showers emit a short (tens of nanoseconds) radio pulse due to deflection of the shower particles in the Earth's magnetic field [3]. Antenna arrays, such as AERA, LOFAR and LOPES detect these pulses in a frequency window of roughly 10-100 MHz. These systems are also sensitive to the radiation from discharges associated to thunderstorms, and provide a means to study the interaction of cosmic ray air showers and the electrical processes in thunderstorms [4]. In this presentation we discuss the involved radiation mechanisms and present analyses of thunderstorm data from air shower arrays [1] A. Gurevich et al., Phys. Lett. A 165, 463 (1992) [2] S. Buitink et al., Astropart. Phys. 33, 1 (2010) [3] H. Falcke et al., Nature 435, 313 (2005) [4] S. Buitink et al., Astron. & Astrophys. 467, 385 (2007)

Half a century of cosmic x-ray research

International Nuclear Information System (INIS)

Makishima, Kazuo; Takahashi, Tadayuki

2012-01-01

The year of 2012, which is the centennial of the cosmic-ray discovery, happens to coincide with the 50th anniversary of the discovery of cosmic X-ray sources. First carried by cosmic-ray physicists, the study of cosmic X-rays has made explosive developments over the last half a century, and has established the X-ray wavelength as an indispensable window onto the Universe. Among a variety of X-ray emitting celestial objects, we choose here neutron stars as a representative, and review the 50 years connecting the dawn era of the research and the state-of-the-art ASTRO-H satellite to be launched in 2014. In this article, 'X-rays' mean energetic photons with energies from 0.1 keV up to a few hundreds keV. (author)

Cosmic ray acceleration by large scale galactic shocks

International Nuclear Information System (INIS)

Cesarsky, C.J.; Lagage, P.O.

1987-01-01

The mechanism of diffusive shock acceleration may account for the existence of galactic cosmic rays detailed application to stellar wind shocks and especially to supernova shocks have been developed. Existing models can usually deal with the energetics or the spectral slope, but the observed energy range of cosmic rays is not explained. Therefore it seems worthwhile to examine the effect that large scale, long-lived galactic shocks may have on galactic cosmic rays, in the frame of the diffusive shock acceleration mechanism. Large scale fast shocks can only be expected to exist in the galactic halo. We consider three situations where they may arise: expansion of a supernova shock in the halo, galactic wind, galactic infall; and discuss the possible existence of these shocks and their role in accelerating cosmic rays

Gravitational-Wave Stochastic Background from Cosmic Strings

International Nuclear Information System (INIS)

Siemens, Xavier; Creighton, Jolien; Mandic, Vuk

2007-01-01

We consider the stochastic background of gravitational waves produced by a network of cosmic strings and assess their accessibility to current and planned gravitational wave detectors, as well as to big bang nucleosynthesis (BBN), cosmic microwave background (CMB), and pulsar timing constraints. We find that current data from interferometric gravitational wave detectors, such as Laser Interferometer Gravitational Wave Observatory (LIGO), are sensitive to areas of parameter space of cosmic string models complementary to those accessible to pulsar, BBN, and CMB bounds. Future more sensitive LIGO runs and interferometers such as Advanced LIGO and Laser Interferometer Space Antenna (LISA) will be able to explore substantial parts of the parameter space

Sealed drift tube cosmic ray veto counters

International Nuclear Information System (INIS)

Rios, R.; Tatar, E.; Bacon, J.D.; Bowles, T.J.; Hill, R.; Green, J.A.; Hogan, G.E.; Ito, T.M.; Makela, M.; Morris, C.L.; Mortenson, R.; Pasukanics, F.E.; Ramsey, J.; Saunders, A.; Seestrom, S.J.; Sondheim, W.E.; Teasdale, W.; Saltus, M.; Back, H.O.; Cottrell, C.R.

2011-01-01

We describe a simple drift tube counter that has been used as a cosmic ray veto for the UCNA experiment, a first-ever measurement of the neutron beta-asymmetry using ultra-cold neutrons. These detectors provide an inexpensive alternative to more conventional scintillation detectors for large area cosmic ray anticoincidence detectors.

RECORD-SETTING COSMIC-RAY INTENSITIES IN 2009 AND 2010

International Nuclear Information System (INIS)

Mewaldt, R. A.; Davis, A. J.; Leske, R. A.; Stone, E. C.; Cummings, A. C.; Labrador, A. W.; Lave, K. A.; Binns, W. R.; Israel, M. H.; Wiedenbeck, M. E.; Christian, E. R.; De Nolfo, G. A.; Von Rosenvinge, T. T.

2010-01-01

We report measurements of record-setting intensities of cosmic-ray nuclei from C to Fe, made with the Cosmic Ray Isotope Spectrometer carried on the Advanced Composition Explorer in orbit about the inner Sun-Earth Lagrangian point. In the energy interval from ∼70 to ∼450 MeV nucleon -1 , near the peak in the near-Earth cosmic-ray spectrum, the measured intensities of major species from C to Fe were each 20%-26% greater in late 2009 than in the 1997-1998 minimum and previous solar minima of the space age (1957-1997). The elevated intensities reported here and also at neutron monitor energies were undoubtedly due to several unusual aspects of the solar cycle 23/24 minimum, including record-low interplanetary magnetic field (IMF) intensities, an extended period of reduced IMF turbulence, reduced solar-wind dynamic pressure, and extremely low solar activity during an extended solar minimum. The estimated parallel diffusion coefficient for cosmic-ray transport based on measured solar-wind properties was 44% greater in 2009 than in the 1997-1998 solar-minimum period. In addition, the weaker IMF should result in higher cosmic-ray drift velocities. Cosmic-ray intensity variations at 1 AU are found to lag IMF variations by 2-3 solar rotations, indicating that significant solar modulation occurs inside ∼20 AU, consistent with earlier galactic cosmic-ray radial-gradient measurements. In 2010, the intensities suddenly decreased to 1997 levels following increases in solar activity and in the inclination of the heliospheric current sheet. We describe the conditions that gave cosmic rays greater access to the inner solar system and discuss some of their implications.

Ambient Noise Tomography and Microseism Directionalities across the Juan de Fuca Plate

Science.gov (United States)

Tian, Ye

Ambient noise tomography has been well developed over the past decade and proven to be effective in studying the crust and upper mantle structure beneath the Earth’s continents. With new seismic array deployments beginning in the oceans, the application of the tomographic methods based on ambient noise observed at ocean bottom seismometers (OBSs) has become an important topic for research. In this thesis, I investigate the application of ambient noise tomography to oceanic bottom seismic data recorded by the Cascadia Initiative experiment across the Juan de Fuca plate. With higher local noise levels recorded by OBSs, I find that traditional data processing procedures used in ambient noise tomography produce measurable Rayleigh wave Green’s functions between deep ocean stations, whereas the shallow water stations are severely contaminated by both tilt noise and compliance noise and require new methods of processing. Because the local noise level varies across the study region, four semi-independent studies are conducted to both utilize the quieter deep-water stations and to address the problem posed by noisy shallow water stations. First, I construct an age-dependent shear wave speed model of the crust and uppermost mantle with 18 deep-water stations near the Juan de Fuca Ridge. The model possess a shallow low shear velocity zone near the ridge and has its sedimentary thickness, lithospheric thickness, and mantle shear wave speeds increase systematically with age Second, I investigate the locations and mechanisms of microseism generation using ambient noise cross-correlations constructed between 61 OBSs and 42 continental stations near the western US coast and find that the primary and secondary microseisms are generated at different locations and possibly have different physical mechanisms. Third, I show that tilt and compliance noise on the vertical components of the OBSs can be reduced substantially using the horizontal components and the differential

The role of cosmic rays in the atmospheric processes

Energy Technology Data Exchange (ETDEWEB)

Stozhkov, Y I [Lebedev Physical Institute, Russian Academy of Sciences, 119991, Leninsky Prospect, 53, Moscow (Russian Federation)

2003-05-01

The energy flux of galactic cosmic rays falling on the earth's atmosphere is small in comparison with solar electromagnetic irradiation (by 10{sup 8} times). But at altitudes of h {approx} 3 to 35 km in the atmosphere, cosmic rays are the only ionization source (from the ground level up to h {approx} 3 km, natural radioactivity is an additional source of ionization). Solar activity modulates cosmic ray flux. The cosmic rays produce atmospheric ions that define the electrical properties of the atmosphere. The electric charges play a very important role in the processes of cloud and thundercloud formation in the operation of the global electric circuit. The changes in electric properties of the atmosphere influence weather and climate. Thus, we have the following chain of the solar terrestrial relationship: solar activity - cosmic ray modulation - changes in the global electric properties of the atmosphere - changes in weather and climate. The following questions are discussed in this paper: light ion production in the atmosphere, role of electric charges in the formation of clouds and thunderclouds, experimental evidences of the relationships between cosmic ray flux and atmospheric current and lightning.

The role of cosmic rays in the atmospheric processes

International Nuclear Information System (INIS)

Stozhkov, Y I

2003-01-01

The energy flux of galactic cosmic rays falling on the earth's atmosphere is small in comparison with solar electromagnetic irradiation (by 10 8 times). But at altitudes of h ∼ 3 to 35 km in the atmosphere, cosmic rays are the only ionization source (from the ground level up to h ∼ 3 km, natural radioactivity is an additional source of ionization). Solar activity modulates cosmic ray flux. The cosmic rays produce atmospheric ions that define the electrical properties of the atmosphere. The electric charges play a very important role in the processes of cloud and thundercloud formation in the operation of the global electric circuit. The changes in electric properties of the atmosphere influence weather and climate. Thus, we have the following chain of the solar terrestrial relationship: solar activity - cosmic ray modulation - changes in the global electric properties of the atmosphere - changes in weather and climate. The following questions are discussed in this paper: light ion production in the atmosphere, role of electric charges in the formation of clouds and thunderclouds, experimental evidences of the relationships between cosmic ray flux and atmospheric current and lightning

Cl36 and the age of the cosmic rays

International Nuclear Information System (INIS)

Casse, M.; Goret, P.; Regnier, S.

1975-01-01

The radioactive isotope 36 Cl (tau=γx3.10 5 y) is used as a time reference for the propagation of cosmic rays. New measurements of the production cross section of 36 Cl in Ti and Fe at 24GeV will be presented. A critical analysis of the cross sections leads to an estimate of the ratio 36 Cl/Cl=0.030+0.007 in the arriving cosmic rays. The comparison between the expected abundance of Cl in the arriving cosmic rays and the observations tend to support the decay of 36 Cl. The inferred cosmic ray confinement time is about 10 6 y [fr

A Bayesian framework for cosmic string searches in CMB maps

Energy Technology Data Exchange (ETDEWEB)

Ciuca, Razvan; Hernández, Oscar F., E-mail: razvan.ciuca@mail.mcgill.ca, E-mail: oscarh@physics.mcgill.ca [Department of Physics, McGill University, 3600 rue University, Montréal, QC, H3A 2T8 (Canada)

2017-08-01

There exists various proposals to detect cosmic strings from Cosmic Microwave Background (CMB) or 21 cm temperature maps. Current proposals do not aim to find the location of strings on sky maps, all of these approaches can be thought of as a statistic on a sky map. We propose a Bayesian interpretation of cosmic string detection and within that framework, we derive a connection between estimates of cosmic string locations and cosmic string tension G μ. We use this Bayesian framework to develop a machine learning framework for detecting strings from sky maps and outline how to implement this framework with neural networks. The neural network we trained was able to detect and locate cosmic strings on noiseless CMB temperature map down to a string tension of G μ=5 ×10{sup −9} and when analyzing a CMB temperature map that does not contain strings, the neural network gives a 0.95 probability that G μ≤2.3×10{sup −9}.

Maximum entropy analysis of cosmic ray composition

Czech Academy of Sciences Publication Activity Database

Nosek, D.; Ebr, Jan; Vícha, Jakub; Trávníček, Petr; Nosková, J.

2016-01-01

Roč. 76, Mar (2016), s. 9-18 ISSN 0927-6505 R&D Projects: GA ČR(CZ) GA14-17501S Institutional support: RVO:68378271 Keywords : ultra-high energy cosmic rays * extensive air showers * cosmic ray composition Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 3.257, year: 2016

Early history of cosmic rays at Chicago

Science.gov (United States)

Yodh, Gaurang B.

2013-02-01

Cosmic ray studies at the University of Chicago were started by Arthur Compton during the late 1920s. The high points of cosmic ray studies at Chicago under Compton and Marcel Schein are the focus of this report, which summarizes the research done at Chicago up to the end of World War II.

Heliospheric Impact on Cosmic Rays Modulation

Science.gov (United States)

Tiwari, Bhupendra Kumar

2016-07-01

Heliospheric Impact on Cosmic RaysModulation B. K. Tiwari Department of Physics, A. P. S. University, Rewa (M.P.), btiwari70@yahoo.com Cosmic rays (CRs) flux at earth is modulated by the heliosphereric magnetic field and the structure of the heliosphere, controls by solar outputs and their variability. Sunspots numbers (SSN) is often treated as a primary indicator of solar activity (SA). GCRs entering the helioshphere are affected by the interplanetary magnetic field (IMF) and solar wind speed, their modulation varies with the varying solar activity. The observation based on data recoded from Omniweb data Centre for solar- interplanetary activity indices and monthly mean count rate of cosmic ray intensity (CRI) data from neutron monitors of different cut-off rigidities(Rc) (Moscow Rc=2.42Gv and Oulu Rc=0.80Gv). During minimum solar activity periodof solar cycle 23/24, the sun is remarkably quiet, weakest strength of the IMF and least dense and slowest, solar wind speed, whereas, in 2003, highest value of yearly averaged solar wind speed (~568 Km/sec) associated with several coronal holes, which generate high speed wind stream has been recorded. It is observed that GCRs fluxes reduces and is high anti-correlated with SSN (0.80) and IMF (0.86). CRI modulation produces by a strong solar flare, however, CME associated solar flare produce more disturbance in the interplanetary medium as well as in geomagnetic field. It is found that count rate of cosmic ray intensity and solar- interplanetary parameters were inverse correlated and solar indices were positive correlated. Keywords- Galactic Cosmic rays (GCRs), Sunspot number (SSN), Solar activity (SA), Coronal Mass Ejection (CME), Interplanetary magnetic field (IMF)

Ultrahigh-energy particles from cosmic strings

International Nuclear Information System (INIS)

Bhattacharjee, P.

1991-02-01

The idea of production of ultrahigh-energy particles in the present universe due to annihilation or collapse of topological defects is discussed. Topological defects, formed in symmetry-breaking phase transitions in the early universe, can survive till today owing to their topological stability. However, under certain circumstances, topological defects may be physically destroyed. When topological defects are destroyed, the energy contained in the defects can be released in the form of massive gauge- and Higgs bosons of the underlying spontaneously broken gauge theory. Subsequent decay of these massive particles can give rise to energetic particles ranging up to an energy on the order of the mass of the original particles released from the defects. This may give us a ''natural'' mechanism of production of extremely energetic cosmic ray particles in the universe today, without the need for any acceleration mechanism. To illustrate this idea, I describe in detail the calculation of the expected ultrahigh-energy proton spectrum due to a specific process which involves collapse or multiple self-intersections of a class of closed cosmic string loops formed in a phase transition at a grand unification energy scale. I discuss the possibility that some of the highest-energy cosmic ray particles are of this origin. By comparing with the observational results on the ultrahigh-energy cosmic rays, we derive an upper limit to the average fraction of the total energy in all ''primary'' cosmic string loops that may be released in the form of particles due to collapse or multiple self-intersections of these loops. No nuclei such as α's or Fe's are in the spectrum. 43 refs., 3 figs

Magnetorheological dampers in shear mode

International Nuclear Information System (INIS)

Wereley, N M; Cho, J U; Choi, Y T; Choi, S B

2008-01-01

In this study, three types of shear mode damper using magnetorheological (MR) fluids are theoretically analyzed: linear, rotary drum, and rotary disk dampers. The damping performance of these shear mode MR dampers is characterized in terms of the damping coefficient, which is the ratio of the equivalent viscous damping at field-on status to the damping at field-off status. For these three types of shear mode MR damper, the damping coefficient or dynamic range is derived using three different constitutive models: the Bingham–plastic, biviscous, and Herschel–Bulkley models. The impact of constitutive behavior on shear mode MR dampers is theoretically presented and compared

Cosmic Times: Astronomy History and Science for the Classroom

Science.gov (United States)

Lochner, James C.; Mattson, B.

2008-05-01

Cosmic Times is a series of curriculum support materials and classroom activities for upper middle school and high school students which teach the nature of science by exploring the history of our understanding of the universe during the past 100 years. Starting with the confirmation of Einstein's theory of gravity in 1919 to the current conundrum posed by the discovery of dark energy, Cosmic Times examines the discoveries, the theories, and the people involved in this changing [understanding] of the universe. Cosmic Times takes the form of 6 posters, each resembling the front page of a newspaper from a particular time in this history with articles describing the discoveries. Each poster is accompanied by 4-5 classroom lessons which enable students to examine the science concepts behind the discoveries, develop techniques to improve science literacy, and investigate the nature of science using historical examples. Cosmic Times directly connects with the IYA theme of Astronomy in the Classroom, as well as the general theme of the impact of astronomy history. Cosmic Times has been developed with a freelance writer to write the articles for the posters, a group of teachers to develop the lessons, and evaluator to provide testing of the materials with a group of rural teachers in underserved communities. This poster presentation previews the Cosmic Times materials, which are posted on http://cosmictimes.gsfc.nasa.gov/ as they become available. Cosmic Times is funded in part via a NASA IDEAS grant.

Could the cosmic acceleration be transient?

Energy Technology Data Exchange (ETDEWEB)

Guimaraes, Antonio C.C.; Lima, J.A.S. [Universidade de Sao Paulo (IAG/USP), SP (Brazil). Inst. de Astronomia, Geofisica e Ciencias Atmosfericas

2011-07-01

Full text: The possibility of a transient cosmic acceleration appears in several theoretical scenarios and is theoretically interesting because it solves some difficulties inherent to eternally accelerating universes (like {Lambda}CDM). On the observational side, some authors, using a dynamical Ansatz for the dark energy equation of state, have suggested that the cosmic acceleration have already peaked and that we are currently witnessing its slowing down. Here, a possible slowing down of the cosmic expansion is investigated through a cosmographic approach. By expanding the luminous distance to fourth order and fitting the SNe Ia data from the most recent compilations (Union, Constitution and Union 2), the marginal likelihood distribution for the deceleration parameter today indicates that there is a considerable probability for q{sub 0} > 0. Also in contrast to the prediction of the {Lambda}CDM model, the cosmographic q(z) reconstruction suggests that the cosmic acceleration could already have peaked and be presently slowing down, what would imply that the recent accelerated expansion of the Universe is a transient phenomenon. It is also shown that to describe a transient acceleration the luminous distance needs to be expanded at least to fourth order. The present cosmographic results depend neither on the validity of general relativity nor on the matter-energy contents of the Universe. (author)

Ultrahigh-energy cosmic rays: facts, myths and legends

International Nuclear Information System (INIS)

Anchordoqui, L.A.

2011-01-01

This is a written version of a series of lectures aimed at graduate students in astrophysics and theoretical/experimental particle physics. In the first part, we explain the important progress made in recent years towards understanding the experimental data on cosmic rays with energies > or approx. 10 8 GeV. We begin with a brief survey of the available data, including a description of the energy spectrum, mass composition and arrival directions. At this point we also give a short overview of experimental techniques. After that, we introduce the fundamentals of acceleration and propagation in order to discuss the conjectured nearby cosmic-ray sources, and emphasize some of the prospects for a new (multiparticle) astronomy. Next, we survey the state of the art regarding the ultrahigh-energy cosmic neutrinos that should be produced in association with the observed cosmic rays. In the second part, we summarize the phenomenology of cosmic-ray air showers. We explain the hadronic interaction models used to extrapolate results from collider data to ultrahigh energies, and describe the prospects for insights into forward physics at the Large Hadron Collider. We also explain the main electromagnetic processes that govern the longitudinal shower evolution. Armed with these two principal shower ingredients and motivation from the underlying physics, we describe the different methods proposed to distinguish primary species. In the last part, we outline how ultrahigh-energy cosmic-ray interactions can be used to probe new physics beyond the electroweak scale. (author)

IMAGE ANALYSIS FOR MODELLING SHEAR BEHAVIOUR

Directory of Open Access Journals (Sweden)

Philippe Lopez

2011-05-01

Full Text Available Through laboratory research performed over the past ten years, many of the critical links between fracture characteristics and hydromechanical and mechanical behaviour have been made for individual fractures. One of the remaining challenges at the laboratory scale is to directly link fracture morphology of shear behaviour with changes in stress and shear direction. A series of laboratory experiments were performed on cement mortar replicas of a granite sample with a natural fracture perpendicular to the axis of the core. Results show that there is a strong relationship between the fracture's geometry and its mechanical behaviour under shear stress and the resulting damage. Image analysis, geostatistical, stereological and directional data techniques are applied in combination to experimental data. The results highlight the role of geometric characteristics of the fracture surfaces (surface roughness, size, shape, locations and orientations of asperities to be damaged in shear behaviour. A notable improvement in shear understanding is that shear behaviour is controlled by the apparent dip in the shear direction of elementary facets forming the fracture.

Cosmic neutrinos as a probe of TeV-scale physics

Energy Technology Data Exchange (ETDEWEB)

Ahlers, M.

2007-02-15

Ultra-high energy cosmic neutrinos are versatile probes of astrophysics, astronomy, and particle physics. They represent the messengers of hadronic processes in cosmic accelerators and survive the propagation through the interstellar medium practically unscathed. We investigate the neutrino fluxes associated with optically thin proton sources which provide a diagnostic of the transition between galactic and extragalactic cosmic rays. The center of mass energies in collisions of these cosmic neutrinos with atomic nuclei in the atmosphere or the Earth's interior easily exceed those so far reached in man-made accelerators. We discuss the prospects of observing supersymmetric neutrino interactions with Cherenkov telescopes and speculate about a neutrino component in extremely high energy cosmic rays from exotic interactions in the atmosphere. (orig.)

Consistency relation for cosmic magnetic fields

DEFF Research Database (Denmark)

Jain, R. K.; Sloth, M. S.

2012-01-01

If cosmic magnetic fields are indeed produced during inflation, they are likely to be correlated with the scalar metric perturbations that are responsible for the cosmic microwave background anisotropies and large scale structure. Within an archetypical model of inflationary magnetogenesis, we show...... that there exists a new simple consistency relation for the non-Gaussian cross correlation function of the scalar metric perturbation with two powers of the magnetic field in the squeezed limit where the momentum of the metric perturbation vanishes. We emphasize that such a consistency relation turns out...... to be extremely useful to test some recent calculations in the literature. Apart from primordial non-Gaussianity induced by the curvature perturbations, such a cross correlation might provide a new observational probe of inflation and can in principle reveal the primordial nature of cosmic magnetic fields. DOI...

Manipulating lightcone fluctuations in an analogue cosmic string

Directory of Open Access Journals (Sweden)

Jiawei Hu

2018-02-01

Full Text Available We study the flight time fluctuations in an anisotropic medium inspired by a cosmic string with an effective fluctuating refractive index caused by fluctuating vacuum electric fields, which are analogous to the lightcone fluctuations due to fluctuating spacetime metric when gravity is quantized. The medium can be realized as a metamaterial that mimics a cosmic string in the sense of transformation optics. For a probe light close to the analogue string, the flight time variance is ν times that in a normal homogeneous and isotropic medium, where ν is a parameter characterizing the deficit angle of the spacetime of a cosmic string. The parameter ν, which is always greater than unity for a real cosmic string, is determined by the dielectric properties of the metamaterial for an analogue string. Therefore, the flight time fluctuations of a probe light can be manipulated by changing the electric permittivity and magnetic permeability of the analogue medium. We argue that it seems possible to fabricate a metamaterial that mimics a cosmic string with a large ν in laboratory so that a currently observable flight time variance might be achieved.

Manipulating lightcone fluctuations in an analogue cosmic string

Science.gov (United States)

Hu, Jiawei; Yu, Hongwei

2018-02-01

We study the flight time fluctuations in an anisotropic medium inspired by a cosmic string with an effective fluctuating refractive index caused by fluctuating vacuum electric fields, which are analogous to the lightcone fluctuations due to fluctuating spacetime metric when gravity is quantized. The medium can be realized as a metamaterial that mimics a cosmic string in the sense of transformation optics. For a probe light close to the analogue string, the flight time variance is ν times that in a normal homogeneous and isotropic medium, where ν is a parameter characterizing the deficit angle of the spacetime of a cosmic string. The parameter ν, which is always greater than unity for a real cosmic string, is determined by the dielectric properties of the metamaterial for an analogue string. Therefore, the flight time fluctuations of a probe light can be manipulated by changing the electric permittivity and magnetic permeability of the analogue medium. We argue that it seems possible to fabricate a metamaterial that mimics a cosmic string with a large ν in laboratory so that a currently observable flight time variance might be achieved.

Planetary Habitability over Cosmic-Time Based on Cosmic-Ray Levels

Science.gov (United States)

Mason, Paul A.; Biermann, Peter L.

2016-01-01

Extreme cosmic-ray (CR) fluxes have a negative effect on life when flux densities are high enough to cause excessive biological, especially DNA, damage. The CR history of a planet plays an important role in its potential surface habitation. Both global and local CR conditions determine the ability of life to survive for astrobiologically relevant time periods. We highlight two CR life-limiting factors: 1) General galactic activity, starburst and AGN, was up by about a factor of 30 at redshift 1 - 2, per comoving frame, averaged over all galaxies. And 2) AGN activity is highly intermittent, so extreme brief but powerful bursts (Her A for example) can be detrimental at great distances. This means that during such brief bursts of AGN activity the extragalactic CRs might even overpower the local galactic CRs. But as shown by the starburst galaxy M82, the local CRs in a starburst can also be quite high. Moreover, in our cosmic neighborhood we have several super-massive black holes. These are in M31, M32, M81, NGC5128 (Cen A), and in our own Galaxy, all within about 4 Mpc today. Within about 20 Mpc today there are many more super-massive black holes. Cen A is of course the most famous one now, since it may be a major source of the ultra-high-energy CRs (UHECRs). Folding in what redshift means in terms of cosmic time, this implies that there may have been little chance for life to survive much earlier than Earth's starting epoch. We speculate, on whether the very slow start oflife on Earth is connected to the decay of disturbing CR activity.

Scientific results from the cosmic background explorer (COBE)

International Nuclear Information System (INIS)

Bennett, C.L.; Boggess, N.W.; Cheng, E.S.; Hauser, M.G.; Kelsall, T.; Mather, J.C.; Moseley, S.H. Jr.; Shafer, R.A.; Silverberg, R.F.; Murdock, T.L.; Smoot, G.F.; Weiss, R.; Wright, E.L.

1993-01-01

The National Aeronautics and Space Administration (NASA) has flown the COBE satellite to observe the Big Bang and the subsequent formation of galaxies and large-scale structure. Data from the Far-Infrared Absolute Spectrophotometer (FIRAS) show that the spectrum of the cosmic microwave background is that of a black body of temperature T = 2.73 ± 0.06 K, with no deviation from a black-body spectrum greater than 0.25% of the peak brightness. The data from the Differential Microwave Radiometers (DMR) show statistically significant cosmic microwave background anisotropy, consistent with a scale-invariant primordial density fluctuation spectrum. Measurements from the Diffuse Infrared Background Experiment (DIRBE) provide new conservation upper limits to the cosmic infrared background. Extensive modeling of solar system and galactic infrared foregrounds is required for further improvement in the cosmic infrared background limits. 104 refs., 1 tab

Cosmic Ray-Air Shower Measurement from Space

Science.gov (United States)

Takahashi, Yoshiyuki

1997-01-01

A feasibility study has been initiated to observe from space the highest energy cosmic rays above 1021 eV. A satellite observatory concept, the Maximum-energy Auger (Air)-Shower Satellite (MASS), is recently renamed as the Orbital Wide-angle Collector (OWL) by taking its unique feature of using a very wide field-of-view (FOV) optics. A huge array of imaging devices (about 10(exp 6) pixels) is required to detect and record fluorescent light profiles of cosmic ray cascades in the atmosphere. The FOV of MASS could extend to as large as about 60 in. diameter, which views (500 - 1000 km) of earth's surface and more than 300 - 1000 cosmic ray events per year could be observed above 1020 eV. From far above the atmosphere, the MASS/OWL satellite should be capable of observing events at all angles including near horizontal tracks, and would have considerable aperture for high energy photon and neutrino observation. With a large aperture and the spatial and temporal resolution, MASS could determine the energy spectrum, the mass composition, and arrival anisotropy of cosmic rays from 1020 eV to 1022 eV; a region hitherto not explored by ground-based detectors such as the Fly's Eye and air-shower arrays. MASS/OWL's ability to identify cosmic neutrinos and gamma rays may help providing evidence for the theory which attributes the above cut-off cosmic ray flux to the decay of topological defects. Very wide FOV optics system of MASS/OWL with a large array of imaging devices is applicable to observe other atmospheric phenomena including upper atmospheric lightning. The wide FOV MASS optics being developed can also improve ground-based gamma-ray observatories by allowing simultaneous observation of many gamma ray sources located at different constellations.

Cosmic disposal of radioactive waste

Energy Technology Data Exchange (ETDEWEB)

Inoue, Y; Morisawa, S [Kyoto Univ. (Japan). Faculty of Engineering

1975-03-01

The technical and economical possibility and safety of the disposal of highly radioactive waste into cosmos are reviewed. The disposal of highly radioactive waste is serious problem to be solved in the near future, because it is produced in large amounts by the reprocessing of spent fuel. The promising methods proposed are (i) underground disposal, (ii) ocean disposal, (iii) cosmic disposal and (iv) extinguishing disposal. The final disposal method is not yet decided internationally. The radioactive waste contains very long life nuclides, for example transuranic elements and actinide elements. The author thinks the most perfect and safe disposal method for these very long life nuclides is the disposal into cosmos. The space vehicle carrying radioactive waste will be launched safely into outer space with recent space technology. The selection of orbit for vehicles (earth satellite or orbit around planets) or escape from solar system, selection of launching rocket type pretreatment of waste, launching weight, and the cost of cosmic disposal were investigated roughly and quantitatively. Safety problem of cosmic disposal should be examined from the reliable safety study data in the future.

The Need for Direct High-Energy Cosmic-Ray Measurements

Science.gov (United States)

Jones, Frank C.; Streitmatter, Robert

2004-01-01

Measuring the chemical composition of the cosmic rays in the energy region of greater than or equal to 10(exp 12)eV would be highly useful in settling several nagging questions concerning the propagation of cosmic rays in the galaxy. In particular an accurate measurement of secondary to primary ratios such as Boron to Carbon would gibe clear evidence as to whether the propagation of cosmic rays is determined by a diffusion coefficient that varies with the particle's energy as E(sup 0.5) or E(sup 0.3). This would go a long ways in helping us to understand the anistropy (or lack thereof) of the highest energy cosmic rays and the power requirements for producing those particles at approximately equal to 10(exp 18) eV which are believed to be highest energy particles produced in the Galaxy. This would be only one of the benefits of a mission such as ACCESS to perform direct particle measurements on very high energy cosmic rays.

Anisotropy of the cosmic background radiation

International Nuclear Information System (INIS)

Silk, J.

1988-01-01

The characteristics of the cosmic microwave background radiation (CBR) are reviewed, focusing on intrinsic anisotropies caused by primordial matter fluctuations. The basic elements of the CBR are outlined and the contributions to anisotropy at different angular scales are discussed. Possible fluctuation spectra that can generate the observed large-scale structure of the universe through gravitational instability and nonlinear evolution are examined and compared with observational searches for cosmic microwave anisotropies. 21 refs

The end of the galactic cosmic ray spectrum

Energy Technology Data Exchange (ETDEWEB)

Stanev, Todor [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)

2007-03-15

We discuss the region of transition between galactic and extragalactic cosmic rays. The exact shapes and compositions of these two components contains information about important parameters of powerful astrophysical sources and the conditions in extragalactic space as well as for the cosmological evolution of the sources of high energy cosmic rays. Several types of experimental data, including the exact shape of the ultrahigh energy cosmic rays, their chemical composition and their anisotropy, and the fluxes of cosmogenic neutrinos have to be included in the solution of this problem.

Measurement of cosmic-ray reconstruction efficiencies in the MicroBooNE LArTPC using a small external cosmic-ray counter

Energy Technology Data Exchange (ETDEWEB)

Acciarri, R.; et al.

2017-07-31

The MicroBooNE detector is a liquid argon time projection chamber at Fermilab designed to study short-baseline neutrino oscillations and neutrino-argon interaction cross-section. Due to its location near the surface, a good understanding of cosmic muons as a source of backgrounds is of fundamental importance for the experiment. We present a method of using an external 0.5 m (L) x 0.5 m (W) muon counter stack, installed above the main detector, to determine the cosmic-ray reconstruction efficiency in MicroBooNE. Data are acquired with this external muon counter stack placed in three different positions, corresponding to cosmic rays intersecting different parts of the detector. The data reconstruction efficiency of tracks in the detector is found to be $\\epsilon_{\\mathrm{data}}=(97.1\\pm0.1~(\\mathrm{stat}) \\pm 1.4~(\\mathrm{sys}))\\%$, in good agreement with the Monte Carlo reconstruction efficiency $\\epsilon_{\\mathrm{MC}} = (97.4\\pm0.1)\\%$. This analysis represents a small-scale demonstration of the method that can be used with future data coming from a recently installed cosmic-ray tagger system, which will be able to tag $\\approx80\\%$ of the cosmic rays passing through the MicroBooNE detector.

Mean wall-shear stress measurements using the micro-pillar shear-stress sensor MPS3

International Nuclear Information System (INIS)

Große, S; Schröder, W

2008-01-01

A new sensor to measure the mean turbulent wall-shear stress in turbulent flows is described. The wall-shear stress sensor MPS 3 has been tested in a well-defined fully developed turbulent pipe flow at Reynolds numbers Re b based on the bulk velocity U b and the pipe diameter D in the range of Re b = 10 000–20 000. The results demonstrate a convincing agreement of the mean wall-shear stress obtained with the new sensor technique with analytical and experimental results from the literature. The sensor device consists of a flexible micro-pillar that extends from the wall into the viscous sublayer. Bending due to the exerting fluid forces, the pillar-tip deflection serves as a measure for the local wall-shear stress. The sensor concept, calibration techniques, the achievable accuracy and error estimates, the fields of application and the sensor limits will be discussed. Furthermore, a first estimate of the pillar dynamic response will be derived showing the potential of the sensor to also measure the turbulent fluctuating wall-shear stress

Does electromagnetic radiation accelerate galactic cosmic rays

Science.gov (United States)

Eichler, D.

1977-01-01

The 'reactor' theories of Tsytovich and collaborators (1973) of cosmic-ray acceleration by electromagnetic radiation are examined in the context of galactic cosmic rays. It is shown that any isotropic synchrotron or Compton reactors with reasonable astrophysical parameters can yield particles with a maximum relativistic factor of only about 10,000. If they are to produce particles with higher relativistic factors, the losses due to inverse Compton scattering of the electromagnetic radiation in them outweigh the acceleration, and this violates the assumptions of the theory. This is a critical restriction in the context of galactic cosmic rays, which have a power-law spectrum extending up to a relativistic factor of 1 million.

Cosmic rays and radiations from the cosmos

International Nuclear Information System (INIS)

Parizot, E.

2005-12-01

This document gathers a lot of recent information concerning cosmic radiations, it is divided into 4 parts. Part I: energy, mass and angular spectra of cosmic rays. Part II: general phenomenology of cosmic rays, this part deals with the standard model, the maximal energy of protons inside supernova remnants, nucleosynthesis of light elements, and super-bubbles. Part III: radiations from the cosmos, this part deals with high energy gamma rays, non-thermal radiation of super-bubbles, positron transport, and the Compton trail of gamma-ray bursts. Part IV: the Pierre Auger observatory (OPA), this part deals with the detection of gamma ray bursts at OPA, the measurement of anisotropy, and top-down models. (A.C.)

The Hubble Web: The Dark Matter Problem and Cosmic Strings

International Nuclear Information System (INIS)

Alexander, Stephon

2009-01-01

I propose a reinterpretation of cosmic dark matter in which a rigid network of cosmic strings formed at the end of inflation. The cosmic strings fulfill three functions: At recombination they provide an accretion mechanism for virializing baryonic and warm dark matter into disks. These cosmic strings survive as configurations which thread spiral and elliptical galaxies leading to the observed flatness of rotation curves and the Tully-Fisher relation. We find a relationship between the rotational velocity of the galaxy and the string tension and discuss the testability of this model.

The Hubble Web: The Dark Matter Problem and Cosmic Strings

Science.gov (United States)

Alexander, Stephon

2009-07-01

I propose a reinterpretation of cosmic dark matter in which a rigid network of cosmic strings formed at the end of inflation. The cosmic strings fulfill three functions: At recombination they provide an accretion mechanism for virializing baryonic and warm dark matter into disks. These cosmic strings survive as configurations which thread spiral and elliptical galaxies leading to the observed flatness of rotation curves and the Tully-Fisher relation. We find a relationship between the rotational velocity of the galaxy and the string tension and discuss the testability of this model.

Microstructural evolution of a model, shear-banding micellar solution during shear startup and cessation.

Science.gov (United States)

López-Barrón, Carlos R; Gurnon, A Kate; Eberle, Aaron P R; Porcar, Lionel; Wagner, Norman J

2014-04-01

We present direct measurements of the evolution of the segmental-level microstructure of a stable shear-banding polymerlike micelle solution during flow startup and cessation in the plane of flow. These measurements provide a definitive, quantitative microstructural understanding of the stages observed during flow startup: an initial elastic response with limited alignment that yields with a large stress overshoot to a homogeneous flow with associated micellar alignment that persists for approximately three relaxation times. This transient is followed by a shear (kink) band formation with a flow-aligned low-viscosity band that exhibits shear-induced concentration fluctuations and coexists with a nearly isotropic band of homogenous, highly viscoelastic micellar solution. Stable, steady banding flow is achieved only after approximately two reptation times. Flow cessation from this shear-banded state is also found to be nontrivial, exhibiting an initial fast relaxation with only minor structural relaxation, followed by a slower relaxation of the aligned micellar fluid with the equilibrium fluid's characteristic relaxation time. These measurements resolve a controversy in the literature surrounding the mechanism of shear banding in entangled wormlike micelles and, by means of comparison to existing literature, provide further insights into the mechanisms driving shear-banding instabilities in related systems. The methods and instrumentation described should find broad use in exploring complex fluid rheology and testing microstructure-based constitutive equations.

Inductive shearing of drilling pipe

Science.gov (United States)

Ludtka, Gerard M.; Wilgen, John; Kisner, Roger; Mcintyre, Timothy

2016-04-19

Induction shearing may be used to cut a drillpipe at an undersea well. Electromagnetic rings may be built into a blow-out preventer (BOP) at the seafloor. The electromagnetic rings create a magnetic field through the drillpipe and may transfer sufficient energy to change the state of the metal drillpipe to shear the drillpipe. After shearing the drillpipe, the drillpipe may be sealed to prevent further leakage of well contents.

Development of cosmic-ray radiography with nuclear emulsion and its applications

International Nuclear Information System (INIS)

Morishima, Kunihiro

2017-01-01

We are developing cosmic-ray radiography with nuclear emulsion. Cosmic-ray radiography is non-destructive inspection technology to take image of inner structure of gigantic objects (nuclear reactor, pyramids, volcanoes and so on). We conducted cosmic-ray radiography of Fukushima Daiichi Nuclear Power Plant from 2014 to 2015 and are conducting cosmic-ray radiography of Pyramids at Egypt from 2015. In this paper, technical details and latest results are presented. (author)

Cosmic-ray neutron simulations and measurements in Taiwan

International Nuclear Information System (INIS)

Chen, Wei-Lin; Jiang, Shiang-Huei; Sheu, Rong-Jiun

2014-01-01

This study used simulations of galactic cosmic ray in the atmosphere to investigate the neutron background environment in Taiwan, emphasising its altitude dependence and spectrum variation near interfaces. The calculated results were analysed and compared with two measurements. The first measurement was a mobile neutron survey from sea level up to 3275 m in altitude conducted using a car-mounted high-sensitivity neutron detector. The second was a previous measured result focusing on the changes in neutron spectra near air/ground and air/water interfaces. The attenuation length of cosmic-ray neutrons in the lower atmosphere was estimated to be 163 g cm -2 in Taiwan. Cosmic-ray neutron spectra vary with altitude and especially near interfaces. The determined spectra near the air/ground and air/water interfaces agree well with measurements for neutrons below 10 MeV. However, the high-energy portion of spectra was observed to be much higher than our previous estimation. Because high-energy neutrons contribute substantially to a dose evaluation, revising the annual sea-level effective dose from cosmic-ray neutrons at ground level in Taiwan to 35 μSv, which corresponds to a neutron flux of 5.30 x 10 -3 n cm -2 s -1 , was suggested. The cosmic-ray neutron background in Taiwan was studied using the FLUKA simulations and field measurements. A new measurement was performed using a car-mounted high-efficiency neutron detector, re-coding real-time neutron counting rates from sea level up to 3275 m. The attenuation of cosmic-ray neutrons in the lower atmosphere exhibited an effective attenuation length of 163 g cm -2 . The calculated neutron counting rates over predicted the measurements by ∼32 %, which leaded to a correction factor for the FLUKA-calculated cosmic-ray neutrons in the lower atmosphere in Taiwan. In addition, a previous measurement regarding neutron spectrum variation near the air/ground and air/water interfaces was re-evaluated. The results showed that the

Balloon test project: Cosmic Ray Antimatter Calorimeter (CRAC)

Science.gov (United States)

Christy, J. C.; Dhenain, G.; Goret, P.; Jorand, J.; Masse, P.; Mestreau, P.; Petrou, N.; Robin, A.

1984-01-01

Cosmic ray observations from balloon flights are discussed. The cosmic ray antimatter calorimeter (CRAC) experiment attempts to measure the flux of antimatter in the 200-600 Mev/m energy range and the isotopes of light elements between 600 and 1,000 Mev/m.

Non-homogeneous flow profiles in sheared bacterial suspensions