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Sample records for particle radii

  1. Upstream particle events close to the bow shock and 200 earth radii upstream - ISEE-1 and ISEE-3 observations

    NASA Technical Reports Server (NTRS)

    Scholer, M.; Hovestadt, D.; Klecker, B.; Ipavich, F. M.; Gloeckler, G.

    1980-01-01

    Two energetic particle events (28 keV - 145 keV) upstream of the earth's bow shock have been investigated with two identical experiments of the Max-Planck-Institut/University of Maryland on ISEE-1 and ISEE-3. Close to the bow shock the particle distribution is more or less isotropic and indicates strong scattering of these particles in the upstream wave field. At ISEE-3 the particles move essentially scatter-free from the general bow shock direction. The temporal evolution of the particle bursts is discussed in terms of the interplanetary magnetic field topology and the scattering conditions.

  2. Energetic charged particle angular distributions near (r less than or equal to 2 Neptune radii) and over the pole of Neptune

    NASA Technical Reports Server (NTRS)

    Mauk, B. H.; Kane, M.; Keath, E. P.; Cheng, A. F.; Krimigis, S. M.

    1990-01-01

    Energetic ion (greater than 28 keV) and electron (greater than 22 keV) pitch angle distributions very close to (r less than or equal to 2 Neptune radii) and over the north planetary pole of Neptune are presented using data from the Low Energy Charged Particle and magnetometer Experiments on the Voyager 2 spacecraft. The particle data are temporally structured and spectrally soft; a similarity with earth-like auroral signatures has previously been noted. However, the pitch angle distributions (showing trapped distributions at high magnetic latitudes) do not support an earth-like auroral interpretation, and alternative explanations for the temporal dynamics must be sought. Between r of about 1.6 and 2.0 Neptune radii and in the vicinity of the magnetic equator, the higher energy ion and electron pitch angle distributions (E greater than or equal to 80 keV) display dramatic 'bite-outs' at 90 deg. This bite-out feature could be caused by interactions with the newly discovered ring 1989N3R.

  3. Nuclear Charge Radii Systematics

    SciTech Connect

    Marinova, Krassimira

    2015-09-15

    This paper is a brief overview of the existing systematics on nuclear mean square charge radii, obtained by a combined analysis of data from different types of experiment. The various techniques yielding data on nuclear charge radii are summarized. Their specific feature complexities and the accuracy and precision of the obtained information are also discussed.

  4. Indirect Determinations of Atomic Radii

    ERIC Educational Resources Information Center

    Walker, Noojin

    1976-01-01

    Describes laboratory activities which relate the mass, volume, density, and radii of atoms through the assumption that the smallest unit of matter is a cubic box containing one atom. From calculations based on macroscopic materials, the author feels that the concept of an atom may be better developed. (CP)

  5. Ab initio molar volumes and Gaussian radii.

    PubMed

    Parsons, Drew F; Ninham, Barry W

    2009-02-12

    Ab initio molar volumes are calculated and used to derive radii for ions and neutral molecules using a spatially diffuse model of the electron distribution with Gaussian spread. The Gaussian radii obtained can be used for computation of nonelectrostatic ion-ion dispersion forces that underlie Hofmeister specific ion effects. Equivalent hard-sphere radii are also derived, and these are in reasonable agreement with crystalline ionic radii. The Born electrostatic self-energy is derived for a Gaussian model of the electronic charge distribution. It is shown that the ionic volumes used in electrostatic calculations of strongly hydrated cosmotropic ions ought best to include the first hydration shell. Ionic volumes for weakly hydrated chaotropic metal cations should exclude electron overlap (in electrostatic calculations). Spherical radii are calculated as well as nonisotropic ellipsoidal radii for nonspherical ions, via their nonisotropic static polarizability tensors. PMID:19140766

  6. DETERMINATION OF STELLAR RADII FROM ASTEROSEISMIC DATA

    SciTech Connect

    Basu, Sarbani; Chaplin, William J.; Elsworth, Yvonne E-mail: w.j.chaplin@bham.ac.u

    2010-02-20

    The NASA Kepler mission is designed to find planets through transits. Accurate and precise radii of the detected planets depend on knowing the radius of the host star accurately, which is difficult unless the temperature and luminosity of the star are known precisely. Kepler, however, has an asteroseismology program that will provide seismic variables that can characterize stellar radii easily, accurately, and extremely precisely. In this paper, we describe the Yale-Birmingham (YB) method to determine stellar radii using a combination of seismic and conventional variables and analyze the effect of these variables on the result. We find that for main-sequence stars, a knowledge of the parallax is not important to get accurate radii using the YB method: we can get results to an accuracy and precision of better than a few percent if we know the effective temperature and the seismic parameters for these stars. Metallicity does not make much difference either. However, good estimates of the effective temperature and metallicity, along with those of the seismic parameters, are essential to determine radii of subgiants properly. On the other hand, for red giants we find that determining radii properly is not possible without a good estimate of the parallax. We find that the so-called 'surface term' in the seismic data has minimal effect on the inferred radii. Uncertainties in the convective mixing length can matter under some circumstances and can cause a systematic shift in the inferred radii. Blind tests with data simulated to match those expected from the asteroseismic survey phase of Kepler show that it will be possible to infer stellar radii successfully using our method.

  7. On the effective ionic radii for ammonium.

    PubMed

    Sidey, Vasyl

    2016-08-01

    A set of effective ionic radii corresponding to different coordination numbers (CNs) and compatible with the radii system by Shannon [Acta Cryst. (1976), A32, 751-767] has been derived for ammonium: 1.40 Å (CN = IV), 1.48 Å (CN = VI), 1.54 Å (CN = VIII) and 1.67 Å (CN = XII). The bond-valence parameters r0 = 2.3433 Å and B = 0.262 Å have been determined for ammonium-fluorine bonds. PMID:27484382

  8. Near-global survey of effective droplet radii in liquid water clouds using ISCCP data

    NASA Technical Reports Server (NTRS)

    Han, Qingyan; Rossow, William B.; Lacis, Andrew B.

    1994-01-01

    A global survey of cloud particle size variations can provide crucial constraints on how cloud processes determine cloud liquid water contents and their variation with temperature, and further, may indicate the magnitude of aerosol effects on clouds. A method, based on a complete radiative transfer model for Advanced Very High Resolution Radiometer (AVHRR)-measured radiances, is described for retrieving cloud particle radii in liquid water clouds from satellite data currently available from the International Satellite Cloud Climatology Project. Results of sensitivity tests and validation studies provide error estimates. AVHRR data from NOAA-9 and NOAA-10 have been analyzed for January, April, July and October in 1987 and 1988. The results of this first survey reveal systematic continental and maritime differences and hemispheric contrasts that are indicative of the effects of associated aerosol concentration differences: cloud droplet radii in continental water clouds are about 2-3 micrometers smaller than in marine clouds, and droplet radii are about 1 micrometer smaller in marine clouds of the Northern Hemisphere than in the Southern Hemisphere. The height dependencies of cloud droplet radii in continental and marine clouds are also consistent with differences in the vertical profiles of aerosol concentration. Significant seasonal and diurnal variations of effective droplet radii are also observed, particularly at lower latitudes. Variations of the relationship between cloud optical thickness and droplet radii may indicate variations in cloud microphysical regimes.

  9. States of 13C with abnormal radii

    NASA Astrophysics Data System (ADS)

    Demyanova, A. S.; Ogloblin, A. A.; Danilov, A. N.; Goncharov, S. A.; Belyaeva, T. L.; Sobolev, Yu. G.; Khlebnikov, S. V.; Burtebaev, N.; Trzaska, W.; Heikkinen, P.; Tyurin, G. P.; Janseitov, D.; Gurov, Yu. B.

    2016-05-01

    Differential cross-sections of the elastic and inelastic 13C + α scattering were measured at E(α) = 90 MeV. The root mean-square radii() of 13C nucleus in the states: 8.86 (1/2-), 3.09 (1/2+) and 9.90 (3/2-) MeV were determined by the Modified diffraction model (MDM). The radii of the first two levels are enhanced compared to that of the ground state of 13C, confirming the suggestion that the 8.86 MeV state is an analogue of the Hoyle state in 12C and the 3.09 MeV state has a neutron halo. Some indications to the abnormally small size of the 9.90 MeV state were obtained.

  10. Matter Radii of Light Halo Nuclei

    NASA Astrophysics Data System (ADS)

    Al-Khalili, J. S.; Tostevin, J. A.

    1996-05-01

    We reexamine the matter radii of diffuse halo nuclei, as deduced from reaction cross section measurements at high energy. Careful consideration is given to the intrinsic few-body structure of these projectiles and the adiabatic nature of the projectile-target interaction. Using 11Li, 11Be, and 8B as examples we show that data require significantly larger matter radii than previously reported. The revised value for 11Li of 3.55 fm is consistent with three-body models with significant 1s-intruder state components, which reproduce experimental 9Li momentum distributions following 11Li breakup, but were hitherto thought to be at variance with cross section data.

  11. Electromagnetic charge radii of pseudoscalar mesons

    SciTech Connect

    Bagchi, B.; Lahiri, A.; Niyogi, S.

    1989-06-01

    The charge radii of the pseudoscalar mesons ..pi../sup +/, /ital K//sup +/, and /ital K//sup 0/ are analyzed in an extended vector-dominance framework and the results are compared with those which follow the nonrelativistic quark model and constituent-quark triangle loop approach. Further, estimates of the root-mean-square relative coordinate parameter are obtained which are in conformity with normal theoretical expectations.

  12. Reliable Radii for M Dwarf Stars

    NASA Astrophysics Data System (ADS)

    Mann, Andrew; Feiden, Gregory A.; Gaidos, Eric

    2015-01-01

    Precise and accurate parameters for late-type (late K and M) dwarf stars are critical for characterizing their planets. A deluge of planets discovered by Kepler has driven the need for even more precise stellar radii. We present our efforts to better constrain the luminosity-radius and Teff-radius relations for late-type (K5-M6) stars, taking advantage of improved techniques to calculate bolometric fluxes and [Fe/H] for M dwarfs. We determine effective temperatures for these stars by comparing observed spectra to atmospheric models, and confirm the accuracy of these temperatures using stars with temperatures determined from long-baseline optical interferometry. Using the Stefan-Boltzmann law we can empirically determine radii for these stars to better than 5%. We find the Teff-radius relation depends strongly on [Fe/H], which was missed in earlier studies that used smaller samples or less precise methods. We expect our empirical relations to be increasingly useful with the arrival of Gaia parallaxes in the near future.

  13. Stellar radii from long-baseline interferometry

    NASA Astrophysics Data System (ADS)

    Kervella, Pierre

    2008-10-01

    Long baseline interferometers now measure the angular diameters of nearby stars with sub-percent accuracy. They can be translated in photospheric radii when the parallax is known, thus creating a novel and powerful constraint for stellar models. I present applications of interferometric radius measurements to the modeling of main sequence stars. Over the last few years, we obtained accurate measurements of the linear radius of many of the nearest stars: Procyon A, 61 Cyg A & B, α Cen A & B, Sirius A, Proxima. . . Firstly, I describe the example of our modeling of Procyon A (F5IV-V) with the CESAM code, constrained using spectrophotometry, the linear radius, and asteroseismic frequencies. I also present our recent results on the low-mass 61 Cyg system (K5V+K7V), for which asteroseismic frequencies have not been detected yet.

  14. Fitted Hanbury-Brown-Twiss radii versus space-time variances in flow-dominated models

    SciTech Connect

    Frodermann, Evan; Heinz, Ulrich; Lisa, Michael Annan

    2006-04-15

    The inability of otherwise successful dynamical models to reproduce the Hanbury-Brown-Twiss (HBT) radii extracted from two-particle correlations measured at the Relativistic Heavy Ion Collider (RHIC) is known as the RHIC HBT Puzzle. Most comparisons between models and experiment exploit the fact that for Gaussian sources the HBT radii agree with certain combinations of the space-time widths of the source that can be directly computed from the emission function without having to evaluate, at significant expense, the two-particle correlation function. We here study the validity of this approach for realistic emission function models, some of which exhibit significant deviations from simple Gaussian behavior. By Fourier transforming the emission function, we compute the two-particle correlation function, and fit it with a Gaussian to partially mimic the procedure used for measured correlation functions. We describe a novel algorithm to perform this Gaussian fit analytically. We find that for realistic hydrodynamic models the HBT radii extracted from this procedure agree better with the data than the values previously extracted from the space-time widths of the emission function. Although serious discrepancies between the calculated and the measured HBT radii remain, we show that a more apples-to-apples comparison of models with data can play an important role in any eventually successful theoretical description of RHIC HBT data.

  15. Fitted Hanbury-Brown Twiss radii versus space-time variances in flow-dominated models

    NASA Astrophysics Data System (ADS)

    Frodermann, Evan; Heinz, Ulrich; Lisa, Michael Annan

    2006-04-01

    The inability of otherwise successful dynamical models to reproduce the Hanbury-Brown Twiss (HBT) radii extracted from two-particle correlations measured at the Relativistic Heavy Ion Collider (RHIC) is known as the RHIC HBT Puzzle. Most comparisons between models and experiment exploit the fact that for Gaussian sources the HBT radii agree with certain combinations of the space-time widths of the source that can be directly computed from the emission function without having to evaluate, at significant expense, the two-particle correlation function. We here study the validity of this approach for realistic emission function models, some of which exhibit significant deviations from simple Gaussian behavior. By Fourier transforming the emission function, we compute the two-particle correlation function, and fit it with a Gaussian to partially mimic the procedure used for measured correlation functions. We describe a novel algorithm to perform this Gaussian fit analytically. We find that for realistic hydrodynamic models the HBT radii extracted from this procedure agree better with the data than the values previously extracted from the space-time widths of the emission function. Although serious discrepancies between the calculated and the measured HBT radii remain, we show that a more apples-to-apples comparison of models with data can play an important role in any eventually successful theoretical description of RHIC HBT data.

  16. THERMAL PROCESSES GOVERNING HOT-JUPITER RADII

    SciTech Connect

    Spiegel, David S.; Burrows, Adam E-mail: burrows@astro.princeton.edu

    2013-07-20

    There have been many proposed explanations for the larger-than-expected radii of some transiting hot Jupiters, including either stellar or orbital energy deposition deep in the atmosphere or deep in the interior. In this paper, we explore the important influences on hot-Jupiter radius evolution of (1) additional heat sources in the high atmosphere, the deep atmosphere, and deep in the convective interior; (2) consistent cooling of the deep interior through the planetary dayside, nightside, and poles; (3) the degree of heat redistribution to the nightside; and (4) the presence of an upper atmosphere absorber inferred to produce anomalously hot upper atmospheres and inversions in some close-in giant planets. In particular, we compare the radius expansion effects of atmospheric and deep-interior heating at the same power levels and derive the power required to achieve a given radius increase when night-side cooling is incorporated. We find that models that include consistent day/night cooling are more similar to isotropically irradiated models when there is more heat redistributed from the dayside to the nightside. In addition, we consider the efficacy of ohmic heating in the atmosphere and/or convective interior in inflating hot Jupiters. Among our conclusions are that (1) the most highly irradiated planets cannot stably have uB {approx}> 10 km s{sup -1} G over a large fraction of their daysides, where u is the zonal wind speed and B is the dipolar magnetic field strength in the atmosphere, and (2) that ohmic heating cannot in and of itself lead to a runaway in planet radius.

  17. Proton radii of Be, B, and C isotopes

    NASA Astrophysics Data System (ADS)

    Kanada-En'yo, Yoshiko

    2015-01-01

    I investigate the neutron number (N ) dependence of root-mean-square radii of point proton distribution (proton radii) of Be, B, and C isotopes with the theoretical method of variation after spin-parity projection in the framework of antisymmetrized molecular dynamics (AMD). The proton radii in Be and B isotopes changes rapidly as N increases, reflecting the cluster structure change along the isotope chains, whereas those in C isotopes show a weak N dependence because of the stable proton structure in nuclei with Z =6 . In neutron-rich Be and B isotopes, the proton radii are remarkably increased by the enhancement of the two-center cluster structure in the prolately deformed neutron structure. I compare the N dependence of the calculated proton radii with the experimental ones reduced from the charge radii determined by isotope shift and those deduced from the charge changing interaction cross section. It is found that the N dependence of proton radii can be a probe to clarify enhancement and weakening of cluster structures.

  18. Hall Determination of Atomic Radii of Alkali Metals

    ERIC Educational Resources Information Center

    Houari, Ahmed

    2008-01-01

    I will propose here an alternative method for determining atomic radii of alkali metals based on the Hall measurements of their free electron densities and the knowledge of their crystal structure. (Contains 2 figures.)

  19. Charge radii in macroscopic-microscopic mass models

    SciTech Connect

    Buchinger, F.; Pearson, J.M.

    2005-11-01

    We show that the FRLDM model currently being used in macroscopic-microscopic fission-barrier calculations gives a rather poor agreement with measured charge radii. Considerable improvement in this respect can be made by adjusting the diffuseness parameter b.

  20. Wetting morphologies on an array of fibers of different radii.

    PubMed

    Sauret, Alban; Boulogne, François; Cébron, David; Dressaire, Emilie; Stone, Howard A

    2015-05-28

    We investigate the equilibrium morphology of a finite volume of liquid placed on two parallel rigid fibers of different radii. As observed for identical radii fibers, the liquid is either in a column morphology or adopts a drop shape depending on the inter-fiber distance. However the cross-sectional area and the critical inter-fiber distance at which the transition occurs are both modified by the polydispersity of the fibers. Using energy considerations, we analytically predict the critical inter-fiber distance corresponding to the transition between the column and the drop morphologies. This distance depends both on the radii of the fibers and on the contact angle of the liquid. We perform experiments using a perfectly wetting liquid on two parallel nylon fibers: the results are in good agreement with our analytical model. The morphology of the capillary bridges between fibers of different radii is relevant to the modeling of large arrays of polydisperse fibers. PMID:25899307

  1. Nuclear States with Abnormally Large Radii (size Isomers)

    NASA Astrophysics Data System (ADS)

    Ogloblin, A. A.; Demyanova, A. S.; Danilov, A. N.; Belyaeva, T. L.; Goncharov, S. A.

    2015-06-01

    Application of the methods of measuring the radii of the short-lived excited states (Modified diffraction model MDM, Inelastic nuclear rainbow scattering method INRS, Asymptotic normalization coefficients method ANC) to the analysis of some nuclear reactions provide evidence of existing in 9Be, 11B, 12C, 13C the excited states whose radii exceed those of the corresponding ground states by ~ 30%. Two types of structure of these "size isomers" were identified: neutron halo an α-clusters.

  2. Neutron Radii from Low Energy Pion Scattering.

    NASA Astrophysics Data System (ADS)

    Gyles, William

    Recent electron scattering measurements and muonic atom studies have allowed precise determinations of the charge distributions of nuclei. Measurements of the neutron distributions, however, have not progressed to this degree of sophistication, largely because of the uncertainties in the hadron-nucleus interaction. Charge distribution measurements provide good tests of nuclear structure calculations, but measurements of neutron distributions will provide independent constraints on these calculations and the potentials used. In this experiment, (pi)('-) differential cross section ratios were measured on pairs of isotopes (('36)S,('32)S), (('34)S,('32)S) with 50 MeV pions and (('26)Mg,('24)Mg) with 45 MeV pions. Absolute differential cross sections were also measured for ('32)S and ('24)Mg. Magnetic spectro -meters were used to collect the data. The cross section ratios were compared to optical model calcula-tions in which the parameters of a Fermi function representing the neutron distribution of the larger isotope of each pair were varied. The rms radius difference between the two isotopes producing the best fit was found to be independent of the details of the optical potential used, as long as the potential produced a fit to the absolute cross sections. The neutron distribution of the larger isotope was also rep-resented as a Fermi function modified by a sum of spherical Bessel functions, the coefficients of which were allowed to vary. The results for the rms radius differences were consistent with the Fermi function fits, except for ('34)S-('32)S, where the results differed by a full standard deviation. The rms radius differences found for the sulfur isotopes agreed with the results of shell-model calculations by Hodgson (Str82,Hod83). The extracted rms radius difference of the magnesium isotopes was one standard deviation less than the shell-model prediction. The results for the Fermi function fits, Fourier Bessell fits and the single particle potential (SPP

  3. ON THE ANOMALOUS RADII OF THE TRANSITING EXTRASOLAR PLANETS

    SciTech Connect

    Laughlin, Gregory; Crismani, Matteo

    2011-03-01

    We present a systematic evaluation of the agreement between the observed radii of 90 well-characterized transiting extrasolar giant planets and their corresponding model radii. Our model radii are drawn from previously published calculations of coreless giant planets that have attained their asymptotic radii, and which have been tabulated for a range of planet masses and equilibrium temperatures. (We report a two-dimensional polynomial fitting function that accurately represents the models.) As expected, the model radii provide a statistically significant improvement over a null hypothesis that the sizes of giant planets are completely independent of mass and effective temperature. As is well known, however, fiducial models provide an insufficient explanation; the planetary radius anomalies, R{identical_to}R{sub obs}-R{sub pred}, are strongly correlated with planetary equilibrium temperature. We find that the radius anomalies have a best-fit dependence, R{proportional_to}T{sub eff}{sup {alpha}}, with {alpha} = 1.4 {+-} 0.6. Incorporating this relation into the model radii leads to substantially less scatter in the radius correlation. The extra temperature dependence represents an important constraint on theoretical models for hot Jupiters. Using simple scaling arguments, we find support for the hypothesis of Batygin and Stevenson that this correlation can be attributed to a planetary heating mechanism that is mediated by magnetohydrodynamic coupling between the planetary magnetic field and near-surface flow that is accompanied by ohmic dissipation at adiabatic depth. Additionally, we find that the temperature dependence is likely too strong to admit kinetic heating as the primary source of anomalous energy generation within the majority of the observed transiting planets.

  4. Evolution of cooperation among mobile agents with heterogenous view radii

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Wang, Wei-Ye; Du, Wen-Bo; Cao, Xian-Bin

    2011-06-01

    In this paper, we study cooperative behavior among mobile agents; the agents have heterogenous view radii and they play the prisoner’s dilemma game with those being within their vision fields. It is found that the cooperation level is remarkably promoted when the heterogeneity of view radii is considered, and the degree distribution of the system is investigated to explain this interesting phenomenon. Moreover, we report that the cooperative behavior is best favored by low density, moderate view radius, and small moving speed. Our findings may be helpful in understanding cooperative behavior in natural and social systems consisting of mobile agents.

  5. Factors affecting the radii of close-in transiting exoplanets

    NASA Astrophysics Data System (ADS)

    Enoch, B.; Collier Cameron, A.; Horne, K.

    2012-04-01

    Context. The radius of an exoplanet may be affected by various factors, including irradiation received from the host star, the mass of the planet and its heavy element content. A significant number of transiting exoplanets have now been discovered for which the mass, radius, semi-major axis, host star metallicity and stellar effective temperature are known. Aims: We use multivariate regression models to determine the power-law dependence of planetary radius on planetary equilibrium temperature Teq, planetary mass Mp, stellar metallicity [Fe/H], orbital semi-major axis a, and tidal heating rate Htidal, for 119 transiting planets in three distinct mass regimes. Methods: We fit models initially to all 119 planets, resulting in fairly high scatter between fitted and observed radii, and subsequently to three subsets of these planets: Saturn-mass planets, Jupiter-mass planets, and high-mass planets. Results: We find models for each subset that fit the observed planetary radii well and show the importance of the various environmental parameters on each subset. Conclusions: We determine that heating leads to larger planet radii, as expected, increasing mass leads to increased or decreased radii of low-mass (<0.5 RJ) and high-mass (>2.0 RJ) planets, respectively (with no mass effect on Jupiter-mass planets), and increased host-star metallicity leads to smaller planetary radii, indicating a relationship between host-star metallicity and planet heavy element content. For Saturn-mass planets, a good fit to the radii may be obtained from log(Rp/RJ) = -0.077 + 0.450 log(Mp/MJ) - 0.314 [Fe/H] + 0.671 log(a/AU) + 0.398 log(Teq/K). The radii of Jupiter-mass planets may be fit by log(Rp/RJ) = - 2.217 + 0.856 log(Teq/K) + 0.291 log(a/AU). High-mass planets' radii are best fit by log(Rp/RJ) = -1.067 + 0.380 log(Teq/K) - 0.093 log(Mp/MJ) - 0.057 [Fe/H] + 0.019 log(Htidal/1 × 1020). These equations produce a very good fit to the observed radii, with a mean absolute difference between

  6. The quantization of the radii of coordination spheres cubic crystals and cluster systems

    NASA Astrophysics Data System (ADS)

    Melnikov, G.; Emelyanov, S.; Ignatenko, N.; Ignatenko, G.

    2016-02-01

    The article deals with the creation of an algorithm for calculating the radii of coordination spheres and coordination numbers cubic crystal structure and cluster systems in liquids. Solution has important theoretical value since it allows us to calculate the amount of coordination in the interparticle interaction potentials, to predict the processes of growth of the crystal structures and processes of self-organization of particles in the cluster system. One option accounting geometrical and quantum factors is the use of the Fibonacci series to construct a consistent number of focal areas for cubic crystals and cluster formation in the liquid.

  7. Accurate nuclear radii and binding energies from a chiral interaction

    DOE PAGESBeta

    Ekstrom, Jan A.; Jansen, G. R.; Wendt, Kyle A.; Hagen, Gaute; Papenbrock, Thomas F.; Carlsson, Boris; Forssen, Christian; Hjorth-Jensen, M.; Navratil, Petr; Nazarewicz, Witold

    2015-05-01

    With the goal of developing predictive ab initio capability for light and medium-mass nuclei, two-nucleon and three-nucleon forces from chiral effective field theory are optimized simultaneously to low-energy nucleon-nucleon scattering data, as well as binding energies and radii of few-nucleon systems and selected isotopes of carbon and oxygen. Coupled-cluster calculations based on this interaction, named NNLOsat, yield accurate binding energies and radii of nuclei up to 40Ca, and are consistent with the empirical saturation point of symmetric nuclear matter. In addition, the low-lying collective Jπ=3- states in 16O and 40Ca are described accurately, while spectra for selected p- and sd-shellmore » nuclei are in reasonable agreement with experiment.« less

  8. Observational constraints on neutron star masses and radii

    NASA Astrophysics Data System (ADS)

    Miller, M. Coleman; Lamb, Frederick K.

    2016-03-01

    Precise and reliable measurements of the masses and radii of neutron stars with a variety of masses would provide valuable guidance for improving models of the properties of cold matter with densities above the saturation density of nuclear matter. Several different approaches for measuring the masses and radii of neutron stars have been tried or proposed, including analyzing the X-ray fluxes and spectra of the emission from neutron stars in quiescent low-mass X-ray binary systems and thermonuclear burst sources; fitting the energy-dependent X-ray waveforms of rotation-powered millisecond pulsars, burst oscillations with millisecond periods, and accretion-powered millisecond pulsars; and modeling the gravitational radiation waveforms of coalescing double neutron star and neutron star - black hole binary systems. We describe the strengths and weaknesses of these approaches, most of which currently have substantial systematic errors, and discuss the prospects for decreasing the systematic errors in each method.

  9. A differential equation for the Generalized Born radii.

    PubMed

    Fogolari, Federico; Corazza, Alessandra; Esposito, Gennaro

    2013-06-28

    The Generalized Born (GB) model offers a convenient way of representing electrostatics in complex macromolecules like proteins or nucleic acids. The computation of atomic GB radii is currently performed by different non-local approaches involving volume or surface integrals. Here we obtain a non-linear second-order partial differential equation for the Generalized Born radius, which may be solved using local iterative algorithms. The equation is derived under the assumption that the usual GB approximation to the reaction field obeys Laplace's equation. The equation admits as particular solutions the correct GB radii for the sphere and the plane. The tests performed on a set of 55 different proteins show an overall agreement with other reference GB models and "perfect" Poisson-Boltzmann based values. PMID:23676843

  10. Accurate nuclear radii and binding energies from a chiral interaction

    SciTech Connect

    Ekstrom, Jan A.; Jansen, G. R.; Wendt, Kyle A.; Hagen, Gaute; Papenbrock, Thomas F.; Carlsson, Boris; Forssen, Christian; Hjorth-Jensen, M.; Navratil, Petr; Nazarewicz, Witold

    2015-05-01

    With the goal of developing predictive ab initio capability for light and medium-mass nuclei, two-nucleon and three-nucleon forces from chiral effective field theory are optimized simultaneously to low-energy nucleon-nucleon scattering data, as well as binding energies and radii of few-nucleon systems and selected isotopes of carbon and oxygen. Coupled-cluster calculations based on this interaction, named NNLOsat, yield accurate binding energies and radii of nuclei up to 40Ca, and are consistent with the empirical saturation point of symmetric nuclear matter. In addition, the low-lying collective Jπ=3- states in 16O and 40Ca are described accurately, while spectra for selected p- and sd-shell nuclei are in reasonable agreement with experiment.

  11. Nuclear charge radii as signature for structural changes

    NASA Astrophysics Data System (ADS)

    Angeli, I.; Marinova, K.

    2016-06-01

    The correlation of nuclear charge radii with other ground and excited state nuclear observables is considered. An empirical approach is used to deal with a large amount of experimental information, which is properly handled to obtain interesting correlations among different observables as one moves away from the line of stability. Especially the appearance of new magic numbers and/or disappearance of traditional ones as well as the onset of deformation in the region of light nuclei (A < 30) are discussed.

  12. Nuclear charge radii of the Te isotopes from muonic atoms

    SciTech Connect

    Shera, E.B.; Hoehn, M.V.; Fricke, G.; Mallot, G.

    1989-01-01

    The muonic atom energies of the 2p-1s and the 3d-2p transitions were measured with a statistical accuracy of better than +- 70 and +- 40 eV, respectively, for /sup 123,124,125,126,128,130/Te. The values for the Barrett equivalent nuclear radii R/sub k//sub ,//sub ..cap alpha../ and for the root-mean-square radii and their differences were calculated first from muonic data alone and second with the addition of published optical data. The latter data provided the radii of /sup 120/Te and /sup 122/Te isotopes, which were not measured by muonic x rays. A combined analysis of the muonic atom and optical isotope shift data yielded high-precision values of the differences in radii ..delta..R/sub k//sub ,//sub ..cap alpha../ (error < +- 0.5 am) and ..delta../sup 1/2/ (error < +- 0.9 am) between the neighboring isotopes. The optical constants for the Te line lambda = 4049 A were determined (including contributions of higher radial moments) to be F = (509 +- 120) mK/fm/sup 2/ and M = -(104 +- 63) x 10/sup 3/ mK. Systematic behavior of the radius differences in neighboring isotopes and isotones of Ba, Xe, Te, and Sn, together with odd-even staggering of the Te isotopes, are discussed in this paper. The ..delta..N = 2 Te isotope shifts between even-A nuclei decrease nearly linearly with increasing N, which can be explained by a successive decreasing deformation in accordance with the observed systematics.

  13. Charge radii of neon isotopes across the sd neutron shell

    SciTech Connect

    Marinova, K.; Geithner, W.; Kappertz, S.; Kloos, S.; Kotrotsios, G.; Neugart, R.; Wilbert, S.; Kowalska, M.; Keim, M.; Blaum, K.; Lievens, P.; Simon, H.

    2011-09-15

    We report on the changes in mean square charge radii of unstable neon nuclei relative to the stable {sup 20}Ne, based on the measurement of optical isotope shifts. The studies were carried out using collinear laser spectroscopy on a fast beam of neutral neon atoms. High sensitivity on short-lived isotopes was achieved thanks to nonoptical detection based on optical pumping and state-selective collisional ionization, which was complemented by an accurate determination of the beam kinetic energy. The new results provide information on the structural changes in the sequence of neon isotopes all across the neutron sd shell, ranging from the proton drip line nucleus and halo candidate {sup 17}Ne up to the neutron-rich {sup 28}Ne in the vicinity of the ''island of inversion.'' Within this range the charge radius is smallest for {sup 24}Ne with N=14 corresponding to the closure of the neutron d{sub 5/2} shell, while it increases toward both neutron shell closures, N=8 and N=20. The general trend of the charge radii correlates well with the deformation effects which are known to be large for several neon isotopes. In the neutron-deficient isotopes, structural changes arise from the onset of proton-halo formation for {sup 17}Ne, shell closure in {sup 18}Ne, and clustering effects in {sup 20,21}Ne. On the neutron-rich side the transition to the island of inversion plays an important role, with the radii in the upper part of the sd shell confirming the weakening of the N=20 magic number. The results add new information to the radii systematics of light nuclei where data are scarce because of the small contribution of nuclear-size effects to the isotope shifts which are dominated by the finite-mass effect.

  14. Nuclear charge radii of the tin isotopes from muonic atoms

    SciTech Connect

    Piller, C.; Gugler, C.; Jacot-Guillarmod, R.; Schaller, L.A.; Schellenberg, L.; Schneuwly, H. ); Fricke, G.; Hennemann, T.; Herberz, J. )

    1990-07-01

    The muonic atom 2{ital p}{sub 1/2}-1{ital s}{sub 1/2} and 2{ital p}{sub 3/2}-1{ital s}{sub 1/2} transition energies were measured with an experimental accuracy of better than 20 ppm for the isotope chain {sup 112,114,116,117,118,119,120,122,124}Sn. Precise values for the Barrett equivalent nuclear radii {ital R}{sub {ital k}{alpha}} and their differences as well as root-mean-square radii were deduced. The {Delta}{ital N}=2 isotope shifts between the even Sn isotopes show a subshell effect at the neutron number {ital N}=64. Otherwise, there is a nearly linear decrease with increasing {ital N}, in accordance with the general systematics of nuclear charge radii. Our muonic atom results are in a good agreement with recent optical data, including odd-even staggering. Hartree-Fock calculations reproduce the general trend but not the subshell effect. Regarding the nuclear polarization corrections, the problem in the 2{ital p} splitting found earlier in {mu}{sup {minus}}-Zr and {mu}{sup {minus}}-Pb seems also to persist in {mu}{sup {minus}}-Sn.

  15. The 3H-3He Charge Radii Difference

    NASA Astrophysics Data System (ADS)

    Myers, L. S.; Arrington, J. R.; Higinbotham, D. W.

    2016-03-01

    The upcoming E12-14-009 [1] experiment at Jefferson Lab will determine the ratio of the electric form factors for the A=3 mirror nuclei 3He and 3H. The measurement will use a 1.1 GeV electron beam, a special collimator plate to allow for simultaneous optics measurements, and the low-activity tritium target being prepared for Jefferson Lab. By observing the dependence of the form factor ratio as a function of Q2 over 0.05-0.09 GeV2, the dependence of the radii extraction on the shape of the form factors is minimized. As a result, we anticipate the uncertainty of the extracted charge radii difference to be 0.03 fm, a reduction of 70% from the current measurement. Using precise measurements of the 3He charge radius from isotopic shift or μHe measurements [2-4], we can deduce the absolute 3H charge radius. The results will provide a direct comparison to recent calculations of the charge radii.

  16. Variable atomic radii for continuum-solvent electrostatics calculation

    NASA Astrophysics Data System (ADS)

    Zhou, Baojing; Agarwal, Manish; Wong, Chung F.

    2008-07-01

    We have developed a method to improve the description of solute cavity defined by the interlocking-sphere model for continuum-solvent electrostatics calculations. Many models choose atomic radii from a finite set of atom types or uses an even smaller set developed by Bondi [J. Phys. Chem. 68, 441 (1964)]. The new model presented here allowed each atom to adapt its radius according to its chemical environment. This was achieved by first approximating the electron density of a molecule by a superposition of atom-centered spherical Gaussian functions. The parameters of the Gaussian functions were then determined by optimizing a function that minimized the difference between the properties from the model and those from ab initio quantum calculations. These properties included the electrostatics potential on molecular surface and the electron density within the core of each atom. The size of each atom was then determined by finding the radius at which the electron density associated with the atom fell to a prechosen value. This value was different for different chemical elements and was chosen such that the averaged radius for each chemical element in a training set of molecules matched its Bondi radius. Thus, our model utilized only a few adjustable parameters—the above density cutoff values for different chemical elements—but had the flexibility of allowing every atom to adapt its radius according to its chemical environment. This variable-radii model gave better solvation energy for 31 small neutral molecules than the Bondi radii did, especially for a quantum mechanics/Poisson-Boltzmann approach we developed earlier. The improvement was most significant for molecules with large dipole moment. Future directions for further improvement are also discussed.

  17. A Technical Memorandum On Core Radii In Lens Statistics

    NASA Astrophysics Data System (ADS)

    Kochanek, Christopher S.

    Quantitative estimates of lensing probabilities must be self-consistent. In particular, for asymptotically isothermal models: (1) using the $(3/2)^{1/2}$ correction for the velocity dispersion overestimates the expected number of lenses by 150\\% and their average separations by 50\\%, thereby introducing large cosmological errors; (2) when a core radius is added to the SIS model, the velocity dispersion must be increased; and (3) cross sections and magnification bias cannot be separated when computing the lensing probability. When we self-consistently calculate the effects of finite core radii in flat cosmological models, we find that the cosmological limits are independent of the core radius.

  18. Matter radii of {sup 32-35}Mg

    SciTech Connect

    Kanungo, R.; Perro, C.; Prochazka, A.; Farinon, F.; Knoebel, R.; Horiuchi, W.; Nociforo, C.; Aumann, T.; Geissel, H.; Gerl, J.; Kindler, B.; Lommel, B.; Mahata, K.; Scheidenberger, C.; Weick, H.; Winkler, M.; Boutin, D.; Lenske, H.; Cortina-Gil, D.; Davids, B.

    2011-02-15

    The interaction cross sections of {sup 32-35}Mg at 900A MeV have been measured using the fragment separator at GSI. The deviation from the r{sub 0}A{sup 1/3} trend is slightly larger for {sup 35}Mg, signaling the possible formation of a longer tail in the neutron distribution for {sup 35}Mg. The radii extracted from a Glauber model analysis with Fermi densities are consistent with models predicting the development of neutron skins.

  19. Unexpectedly large charge radii of neutron-rich calcium isotopes

    NASA Astrophysics Data System (ADS)

    Garcia Ruiz, R. F.; Bissell, M. L.; Blaum, K.; Ekström, A.; Frömmgen, N.; Hagen, G.; Hammen, M.; Hebeler, K.; Holt, J. D.; Jansen, G. R.; Kowalska, M.; Kreim, K.; Nazarewicz, W.; Neugart, R.; Neyens, G.; Nörtershäuser, W.; Papenbrock, T.; Papuga, J.; Schwenk, A.; Simonis, J.; Wendt, K. A.; Yordanov, D. T.

    2016-06-01

    Despite being a complex many-body system, the atomic nucleus exhibits simple structures for certain `magic’ numbers of protons and neutrons. The calcium chain in particular is both unique and puzzling: evidence of doubly magic features are known in 40,48Ca, and recently suggested in two radioactive isotopes, 52,54Ca. Although many properties of experimentally known calcium isotopes have been successfully described by nuclear theory, it is still a challenge to predict the evolution of their charge radii. Here we present the first measurements of the charge radii of 49,51,52Ca, obtained from laser spectroscopy experiments at ISOLDE, CERN. The experimental results are complemented by state-of-the-art theoretical calculations. The large and unexpected increase of the size of the neutron-rich calcium isotopes beyond N = 28 challenges the doubly magic nature of 52Ca and opens new intriguing questions on the evolution of nuclear sizes away from stability, which are of importance for our understanding of neutron-rich atomic nuclei.

  20. Correlating hydrodynamic radii with that of two-dimensional nanoparticles

    SciTech Connect

    Yue, Yuan; Kan, Yuwei; Clearfield, Abraham; Choi, Hyunho; Liang, Hong

    2015-12-21

    Dynamic light scattering (DLS) is one of the most adapted methods to measure the size of nanoparticles, as referred to the hydrodynamic radii (R{sub h}). However, the R{sub h} represents only that of three-dimensional spherical nanoparticles. In the present research, the size of two-dimensional (2D) nanoparticles of yttrium oxide (Y{sub 2}O{sub 3}) and zirconium phosphate (ZrP) was evaluated through comparing their hydrodynamic diameters via DLS with lateral sizes obtained using scanning and transmission electron microscopy. We demonstrate that the hydrodynamic radii are correlated with the lateral sizes of both square and circle shaped 2D nanoparticles. Two proportional coefficients, i.e., correcting factors, are proposed for the Brownian motion status of 2D nanoparticles. The correction is possible by simplifying the calculation of integrals in the case of small thickness approximation. The correcting factor has great significance for investigating the translational diffusion behavior of 2D nanoparticles in a liquid and in effective and low-cost measurement in terms of size and morphology of shape-specific nanoparticles.

  1. Correlating hydrodynamic radii with that of two-dimensional nanoparticles

    NASA Astrophysics Data System (ADS)

    Yue, Yuan; Kan, Yuwei; Choi, Hyunho; Clearfield, Abraham; Liang, Hong

    2015-12-01

    Dynamic light scattering (DLS) is one of the most adapted methods to measure the size of nanoparticles, as referred to the hydrodynamic radii (Rh). However, the Rh represents only that of three-dimensional spherical nanoparticles. In the present research, the size of two-dimensional (2D) nanoparticles of yttrium oxide (Y2O3) and zirconium phosphate (ZrP) was evaluated through comparing their hydrodynamic diameters via DLS with lateral sizes obtained using scanning and transmission electron microscopy. We demonstrate that the hydrodynamic radii are correlated with the lateral sizes of both square and circle shaped 2D nanoparticles. Two proportional coefficients, i.e., correcting factors, are proposed for the Brownian motion status of 2D nanoparticles. The correction is possible by simplifying the calculation of integrals in the case of small thickness approximation. The correcting factor has great significance for investigating the translational diffusion behavior of 2D nanoparticles in a liquid and in effective and low-cost measurement in terms of size and morphology of shape-specific nanoparticles.

  2. Hypergravity effects on normal and avulsed developing avian radii

    NASA Technical Reports Server (NTRS)

    Negulesco, J. A.; Clark, D. L.

    1976-01-01

    Rhode Island red female chicks were subjected to complete closed fracture of the right radius at 2 weeks post-hatching. The animals were allowed to heal for 1 week at either earth-gravity or 2-G-hypergravity state with control and estrogen-injected groups. Intact and fractured radial length, weight, average epiphysial-diaphysial diameters, and length, width, and weight of healing fracture callus were measured. Daily 2000 IU estrogen administration for 7 d increased intact radial length. Estrogen augments the effects of the 2-G state by inhibiting growth and depleting the mass of both intact and fractured radii and by decreasing the average distal epiphysial diameter of fractured bones. Animals exposed to the hypergravity state without hormonal treatment showed decreased fractured radial length, weight, and smaller proximal epiphysial diameters. The measurable parameters of the fracture callus (width, length, and weight) were depressed by the hypergravity state regardless of whether the animal was untreated or supplemented with estrogen.

  3. Small radii of neutron stars as an indication of novel in-medium effects

    NASA Astrophysics Data System (ADS)

    Jiang, Wei-Zhou; Li, Bao-An; Fattoyev, F. J.

    2015-09-01

    At present, neutron star radii from both observations and model predictions remain very uncertain. Whereas different models can predict a wide range of neutron star radii, it is not possible for most models to predict radii that are smaller than about 10km, thus if such small radii are established in the future they will be very difficult to reconcile with model estimates. By invoking a new term in the equation of state that enhances the energy density, but leaves the pressure unchanged we simulate the current uncertainty in the neutron star radii. This new term can be possibly due to the exchange of the weakly interacting light U-boson with appropriate in-medium parameters, which does not compromise the success of the conventional nuclear models. The validity of this new scheme will be tested eventually by more precise measurements of neutron star radii.

  4. Calculations of neutron and proton radii of cesium isotopes. Final report, April 23--September 30, 1993

    SciTech Connect

    Not Available

    1993-12-31

    This task involved the calculation of neutron and proton radii of cesium isotopes. The author has written a computer code that calculates radii according to two models: Myers 1983 and FRDM 1992. Results of calculations in both these models for both cesium and francium isotopes are attached as figures. He is currently interpreting these results in collaboration with D. Vieira and J.R. Nix, and they expect to use the computer code for further studies of nuclear radii.

  5. Charge radii in macroscopic-microscopic mass models of reflection asymmetry

    SciTech Connect

    Iimura, H.; Buchinger, F.

    2008-12-15

    We show that the charge radii of reflection-asymmetric nuclei calculated in the frame of the finite-range droplet model are in better agreement with measured charge radii when reflection asymmetry is taken into account. However discrepancies between experimental and calculated changes in mean square charge radii still remain for some isotopic chains. These discrepancies cannot be removed by empirically including dynamic contributions to the quadrupole deformation.

  6. The Effective Temperatures, Radii and Masses of Dwarf Cepheids

    NASA Astrophysics Data System (ADS)

    Kim, Chulhee

    1996-02-01

    Using the flux values determined with the infrared flux method (IRFM) developed by Blackwell and Lynas-Gray (1993), we derived the empirical relationship between flux (F v ) and (V — K) colour appropriate to Dwarf Cepheids. For three Dwarf Cepheids CY Aqr, YZ Boo and SZ Lyn where both VK photometry and radial velocities were available from the literature, effective temperatures were determined using the intrinsic Strömgren indices, model atmosphere grids for (V — K) and the relation between temperature and (V — K) colour. Then, by applying the infrared surface brightness method, radii and distances and hence masses and absolute magnitudes were estimated with effective temperatures determined by three different methods. It was found that the average mass of these variables is about 0.5 solar mass and this result supports the hypothesis that Dwarf Cepheids are pre-white dwarf objects. It was also confirmed that the temperatures determined with the IRFM are most successful in the application of the surface brightness method to the radius estimation of Dwarf Cepheids.

  7. The California-Kepler Survey: Precise Planet Radii and Metallicities

    NASA Astrophysics Data System (ADS)

    Howard, Andrew; Marcy, G. W.; Johnson, J. A.; Morton, T. D.; Isaacson, H.

    2012-01-01

    For the small subset of sub-Neptune-size planets with well-measured masses and radii, bulk density varies by an order of magnitude, owing to great diversity in composition and atmospheric content. The ensemble of small planets discovered by Kepler have a radius distribution that rises steeply with decreasing size, with close-in sub-Neptune-size planets being an order of magnitude more common than hot Jupiters. However, the detailed structure of the planet radius distribution remains partially veiled by poorly known stellar properties from the Kepler Input Catalog (KIC). Correlations of planet properties with stellar properties are similarly out of focus or unknown. To measure these crucial properties, our team is compiling a new catalog of stellar parameters for the Kepler planet hosts based on LTE modeling of high-resolution Keck-HIRES spectra. I will present initial results from this catalog. We expect detailed structure of the planet radius distribution to emerge, including deviations from a power-law model that suggest common planet sizes and preferred formation scenarios. It will also shed light on the variations of planet occurrence with orbital distance and stellar mass/metallicity, offering important clues for the formation of small worlds.

  8. Rotating neutron stars with exotic cores: masses, radii, stability

    NASA Astrophysics Data System (ADS)

    Haensel, P.; Bejger, M.; Fortin, M.; Zdunik, L.

    2016-03-01

    A set of theoretical mass-radius relations for rigidly rotating neutron stars with exotic cores, obtained in various theories of dense matter, is reviewed. Two basic observational constraints are used: the largest measured rotation frequency (716Hz) and the maximum measured mass (2 M ⊙ . The present status of measuring the radii of neutron stars is described. The theory of rigidly rotating stars in general relativity is reviewed and limitations of the slow rotation approximation are pointed out. Mass-radius relations for rotating neutron stars with hyperon and quark cores are illustrated using several models. Problems related to the non-uniqueness of the crust-core matching are mentioned. Limits on rigid rotation resulting from the mass-shedding instability and the instability with respect to the axisymmetric perturbations are summarized. The problem of instabilities and of the back-bending phenomenon are discussed in detail. Metastability and instability of a neutron star core in the case of a first-order phase transition, both between pure phases, and into a mixed-phase state, are reviewed. The case of two disjoint families (branches) of rotating neutron stars is discussed and generic features of neutron-star families and of core-quakes triggered by the instabilities are considered.

  9. DNA stretching on the wall surfaces in curved microchannels with different radii

    PubMed Central

    2014-01-01

    DNA molecule conformation dynamics and stretching were made on semi-circular surfaces with different radii (500 to 5,000 μm) in microchannels measuring 200 μm × 200 μm in cross section. Five different buffer solutions - 1× Tris-acetate-EDTA (TAE), 1× Tris-borate-EDTA (TBE), 1× Tris-EDTA (TE), 1× Tris-phosphate-EDTA (TPE), and 1× Tris-buffered saline (TBS) solutions - were used with a variety of viscosity such as 40, 60, and 80 cP, with resultant 10−4 ≤ Re ≤ 10−3 and the corresponding 5 ≤ Wi ≤ 12. The test fluids were seeded with JOJO-1 tracer particles for flow visualization and driven through the test channels via a piezoelectric (PZT) micropump. Micro particle image velocimetry (μPIV) measuring technique was applied for the centered-plane velocity distribution measurements. It is found that the radius effect on the stretch ratio of DNA dependence is significant. The stretch ratio becomes larger as the radius becomes small due to the larger centrifugal force. Consequently, the maximum stretch was found at the center of the channel with a radius of 500 μm. PMID:25147488

  10. DNA stretching on the wall surfaces in curved microchannels with different radii

    NASA Astrophysics Data System (ADS)

    Hsieh, Shou-Shing; Wu, Fong-He; Tsai, Ming-Ju

    2014-08-01

    DNA molecule conformation dynamics and stretching were made on semi-circular surfaces with different radii (500 to 5,000 μm) in microchannels measuring 200 μm × 200 μm in cross section. Five different buffer solutions - 1× Tris-acetate-EDTA (TAE), 1× Tris-borate-EDTA (TBE), 1× Tris-EDTA (TE), 1× Tris-phosphate-EDTA (TPE), and 1× Tris-buffered saline (TBS) solutions - were used with a variety of viscosity such as 40, 60, and 80 cP, with resultant 10-4 ≤ Re ≤ 10-3 and the corresponding 5 ≤ Wi ≤ 12. The test fluids were seeded with JOJO-1 tracer particles for flow visualization and driven through the test channels via a piezoelectric (PZT) micropump. Micro particle image velocimetry (μPIV) measuring technique was applied for the centered-plane velocity distribution measurements. It is found that the radius effect on the stretch ratio of DNA dependence is significant. The stretch ratio becomes larger as the radius becomes small due to the larger centrifugal force. Consequently, the maximum stretch was found at the center of the channel with a radius of 500 μm.

  11. Proton Radii of B12-17 Define a Thick Neutron Surface in B17

    NASA Astrophysics Data System (ADS)

    Estradé, A.; Kanungo, R.; Horiuchi, W.; Ameil, F.; Atkinson, J.; Ayyad, Y.; Cortina-Gil, D.; Dillmann, I.; Evdokimov, A.; Farinon, F.; Geissel, H.; Guastalla, G.; Janik, R.; Kimura, M.; Knöbel, R.; Kurcewicz, J.; Litvinov, Yu. A.; Marta, M.; Mostazo, M.; Mukha, I.; Nociforo, C.; Ong, H. J.; Pietri, S.; Prochazka, A.; Scheidenberger, C.; Sitar, B.; Strmen, P.; Suzuki, Y.; Takechi, M.; Tanaka, J.; Tanihata, I.; Terashima, S.; Vargas, J.; Weick, H.; Winfield, J. S.

    2014-09-01

    The first determination of radii of point proton distribution (proton radii) of B12-17 from charge-changing cross sections (σCC) measurements at the FRS, GSI, Darmstadt is reported. The proton radii are deduced from a finite-range Glauber model analysis of the σCC. The radii show an increase from B13 to B17 and are consistent with predictions from the antisymmetrized molecular dynamics model for the neutron-rich nuclei. The measurements show the existence of a thick neutron surface with neutron-proton radius difference of 0.51(0.11) fm in B17.

  12. MASSES, RADII, AND CLOUD PROPERTIES OF THE HR 8799 PLANETS

    SciTech Connect

    Marley, Mark S.; Saumon, Didier; Cushing, Michael; Ackerman, Andrew S.; Fortney, Jonathan J.; Freedman, Richard E-mail: dsaumon@lanl.gov E-mail: andrew.ackerman@nasa.gov E-mail: freedman@darkstar.arc.nasa.gov

    2012-08-01

    The near-infrared colors of the planets directly imaged around the A star HR 8799 are much redder than most field brown dwarfs of the same effective temperature. Previous theoretical studies of these objects have concluded that the atmospheres of planets b, c, and d are unusually cloudy or have unusual cloud properties. Some studies have also found that the inferred radii of some or all of the planets disagree with expectations of standard giant planet evolution models. Here, we compare the available data to the predictions of our own set of atmospheric and evolution models that have been extensively tested against observations of field L and T dwarfs, including the reddest L dwarfs. Unlike some previous studies, we require mutually consistent choices for effective temperature, gravity, cloud properties, and planetary radius. This procedure thus yields plausible values for the masses, effective temperatures, and cloud properties of all three planets. We find that the cloud properties of the HR 8799 planets are not unusual but rather follow previously recognized trends, including a gravity dependence on the temperature of the L to T spectral transition-some reasons for which we discuss. We find that the inferred mass of planet b is highly sensitive to whether or not we include the H- and the K-band spectrum in our analysis. Solutions for planets c and d are consistent with the generally accepted constraints on the age of the primary star and orbital dynamics. We also confirm that, like in L and T dwarfs and solar system giant planets, non-equilibrium chemistry driven by atmospheric mixing is also important for these objects. Given the preponderance of data suggesting that the L to T spectral type transition is gravity dependent, we present an exploratory evolution calculation that accounts for this effect. Finally we recompute the bolometric luminosity of all three planets.

  13. Galaxy Structure: Core Radii, and Central Mass Deficits

    NASA Astrophysics Data System (ADS)

    Graham, A. W.; Trujillo, I.; Erwin, P.

    2004-05-01

    We investigate the nuclear and global structure of elliptical galaxies, and the apparent disparity between the Nuker and Sérsic light-profile models. We show that the so-called ``power-law" galaxies in fact have Sérsic r1/n profiles over their entire observed radial range. Consequently, only three (Sérsic-profile) parameters are required to simultaneously describe both the inner (HST-resolved) and outer profiles of low-luminosity (M > -20.5 B-mag) elliptical galaxies. We also find that ``core galaxies" have Sérsic profiles with a (partially evacuated) single power-law core. We have developed a modified (5-parameter) Sérsic profile with a power-law core to model the complete radial extent of luminous galaxies with cores. In addition to quantifying the global stellar distribution in these systems, we have derived new estimates of their core radii and other central properties. Comparison of the central stellar deficits with the galaxies' black hole masses suggests that the number of (dissipationless) major mergers that have produced luminous elliptical galaxies is around 1-2, rather than 8-10, which agrees with theory and implies that the galactic merger history of the Universe is roughly an order of magnitude less violent than previous observational analyses had suggested. Support for proposal number HST-AR-09927.01-A was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  14. THE OBSERVATIONAL AND THEORETICAL TIDAL RADII OF GLOBULAR CLUSTERS IN M87

    SciTech Connect

    Webb, Jeremy J.; Sills, Alison; Harris, William E.

    2012-02-10

    Globular clusters have linear sizes (tidal radii) which theory tells us are determined by their masses and by the gravitational potential of their host galaxy. To explore the relationship between observed and expected radii, we utilize the globular cluster population of the Virgo giant M87. Unusually deep, high signal-to-noise images of M87 are used to measure the effective and limiting radii of approximately 2000 globular clusters. To compare with these observations, we simulate a globular cluster population that has the same characteristics as the observed M87 cluster population. Placing these simulated clusters in the well-studied tidal field of M87, the orbit of each cluster is solved and the theoretical tidal radius of each cluster is determined. We compare the predicted relationship between cluster size and projected galactocentric distance to observations. We find that for an isotropic distribution of cluster velocities, theoretical tidal radii are approximately equal to observed limiting radii for R{sub gc} < 10 kpc. However, the isotropic simulation predicts a steep increase in cluster size at larger radii, which is not observed in large galaxies beyond the Milky Way. To minimize the discrepancy between theory and observations, we explore the effects of orbital anisotropy on cluster sizes, and suggest a possible orbital anisotropy profile for M87 which yields a better match between theory and observations. Finally, we suggest future studies which will establish a stronger link between theoretical tidal radii and observed radii.

  15. Masses, Radii, and Cloud Properties of the HR 8799 Planets

    NASA Technical Reports Server (NTRS)

    Marley, Mark S.; Saumon, Didier; Cushing, Michael; Ackerman, Andrew S.; Fortney, Jonathan J.; Freedman, Richard

    2012-01-01

    The near-infrared colors of the planets directly imaged around the A star HR 8799 are much redder than most field brown dwarfs of the same effective temperature. Previous theoretical studies of these objects have compared the photometric and limited spectral data of the planets to the predictions of various atmosphere and evolution models and concluded that the atmospheres of planets b, c, and d are unusually cloudy or have unusual cloud properties. Most studies have also found that the inferred radii of some or all of the planets disagree with expectations of standard giant planet evolution models. Here we compare the available data to the predictions of our own set of atmospheric and evolution models that have been extensively tested against field L and T dwarfs, including the reddest L dwarfs. Unlike almost all previous studies we specify mutually self-consistent choices for effective temperature, gravity, cloud properties, and planetary radius. This procedure yields plausible and self-consistent values for the masses, effective temperatures, and cloud properties of all three planets. We find that the cloud properties of the HR 8799 planets are in fact not unusual but rather follow previously recognized trends including a gravity dependence on the temperature of the L to T spectral transition, some reasons for which we discuss. We find that the inferred mass of planet b is highly sensitive to the H and K band spectrum. Solutions for planets c and particularly d are less certain but are consistent with the generally accepted constraints on the age of the primary star and orbital dynamics. We also confirm that as for L and T dwarfs and solar system giant planets, non-equilibrium chemistry driven by atmospheric mixing is also important for these objects. Given the preponderance of data suggesting that the L to T spectral type transition is gravity dependent, we present a new evolution calculation that predicts cooling tracks on the near-infrared color

  16. Source parameters from identified hadron spectra and HBT radii for AuAu collisions at S=200 GeV in PHENIX

    NASA Astrophysics Data System (ADS)

    Burward-Hoy, J. M.; PHENIX Collaboration

    2003-03-01

    The characteristics of the particle emitting source are deduced from low pT identified hadron spectra ((mT - m0) < 1GeV) and HBT radii using a hydrodynamic interpretation. From the most peripheral to the most central data, the single particle spectra are fit simultaneously for all π±, K±, and p¯/p using the parameterization in [1] and assuming a linear transverse flow profile. Within the systematic uncertainties, the expansion parameters Tfo and βT, respectively decrease and increase with the number of participants, saturating for both at mid-centrality. The expansion using analytic calculations of the kT dependence of HBT radii in [2] is fit to the data but not χ2 minimum is found.

  17. Bonded Radii and the Contraction of the Electron Density of the Oxygen Atom by Bonded Interactions

    SciTech Connect

    Gibbs, Gerald V.; Ross, Nancy L.; Cox, David F.; Rosso, Kevin M.; Iversen, Bo B.; Spackman, M. A.

    2013-02-21

    The bonded radii for more than 550 bonded pairs of atoms, comprising more than 50 crystals, determined from experimental and theoretical electron density distributions, are compared with the effective ionic, ri(M), and crystal radii, rc(M), for metal atoms, M, bonded to O atoms. At odds with the fixed ionic radius of 1.40 Å, assumed for the O atom in the compilation of the ionic radii, the bonded radius for the atom, rb(O), is not fixed but displays a relatively wide range of values as the O atom is progressively polarized by the M-O bonded interactions: as such, rb(O) decreases systematically from 1.40 Å (the Pauling radius of the oxide anion) as bond lengths decrease when bonded to an electropositive atom like sodium, to 0.64 Å (Bragg’s atomic radius of the O atom) when bonded to an electronegative atom like nitrogen. Both rb(M) and rb(O) increase in tandum with the increasing coordination number of the M atom. The bonded radii of the M atoms are highly correlated with both ri(M) and rc(M), but they both depart systematically from rb(M) and become smaller as the electronegativity of the M atom increases and the M-O bond length decreases. The well-developed correlations between both sets of radii and rb(M) testifies to the relative precision of both sets of radii and the fact that both sets are highly correlated the M-O bond 1 lengths. On the other hand, the progressive departure of rb(O) from the fixed ionic radius of the O atom with the increasing electronegativity of the bonded M atom indicates that any compilation of sets of ionic radii, assuming that the radius for the oxygen atom is fixed in value, is problematical and impacts on the accuracy of the resulting sets of ionic and crystal radii thus compiled. The assumption of a fixed O atom radius not only results in a negative ionic radii for several atoms, but it also results in values of rb(M) that are much as ~ 0.6 Å larger than the ri(M) and rc(M) values, respectively, particularly for the more

  18. Acceleration of protons at 32 Jovian radii in the outer magnetosphere of jupiter

    NASA Technical Reports Server (NTRS)

    Schardt, A. W.; Mcdonald, F. B.; Trainor, J. H.

    1977-01-01

    During the inbound pass of Pioneer 10, a rapid ten-fold increase of the 0.2 to MeV proton flux was observed at 32 Jovian radii (R sub J). The total event lasted for 30 minutes and was made up of a number of superimposed individual events. At the time, the spacecraft was in the outer magnetosphere about 7 R sub J below the magnetic equator. Before and after the event, the proton flux was characteristic of the low flux level normally encountered between crossings of the magnetic equator. Flux changes at different energies were coherent within 1 minute; a time comparable to the time resolution of the data. The angular distributions were highly anisotropic with protons streaming towards Jupiter. A field-aligned dumbbell distribution was observed initially, and a pancake distribution just before the flux decayed to its pre-event value. The alpha particle flux changed as rapidly as the proton flux but peaked at different times. The energetic electron flux behaved differently; it increased gradually throughout the period.

  19. Description of Charge Radii in Halo Nuclei within the Gamow Shell Model

    SciTech Connect

    Papadimitriou, G.; Michel, N.; Nazarewicz, W.; Ploszajczak, M.; Rotureau, J.

    2009-05-07

    The charge radius of the halo nucleus {sup 6}He is studied within the framework of the Gamow Shell Model (GSM). The charge radius carries information about the size of the neutron halo, the recoil of the core, and the effective interaction between valence nucleons. The motivation for this work stems from the precise measurements of charge radii in {sup 6,8}He, {sup 11}Li, and {sup 11}Be. For these weakly bound nuclei, the proper treatment of the particle continuum turns out to be crucial. The GSM is a tool that can properly account for the coupling of the continuum space (of both resonant and scattering character) with that of the bound states. We use a GSM Hamiltonian written explicitly in intrinsic coordinates. This guarantees that the core recoil effect is properly described and the spurious center-of-mass motion is removed. According to our calculations for {sup 6}He, the charge radius is very sensitive to (i) the halo extent given by the two-neutron separation energy of the system, and (ii) the p{sub 3/2} occupation. In particular, we show that the two-body wave function of halo neutrons in {sup 6}He should contain {approx}91% of a p{sub 3/2} partial wave to reproduce the charge radius. This observation will help us to construct a GSM effective interaction on the interface of p and sd shells that is needed to describe other halo systems.

  20. Particle Tracking of Fluorescent Microspheres

    NASA Astrophysics Data System (ADS)

    Kaminski, Zofia; Mueller, Joachim; Berk, Serkan

    2010-10-01

    In this research, the diffusion coefficients of the fluorescent microspheres and the relation of those coefficients to particle radius were investigated. An additional focus was to see how well the measured radius of the microspheres compared to the radius as reported by the manufacturer and to measure the distribution of radii in a sample. This study further developed the critical process of ensuring particle movement within the sample volume and made preliminary sample measurements.The methods developed for tracking microspheres will later be used to determine the radii of virus like particles (VLPs), which are a non-infectious model system of the HIV virus. Results from our measurements will be reported.

  1. The Masses and Radii of the Eclipsing Binary zeta Aurigae

    NASA Astrophysics Data System (ADS)

    Bennett, Philip D.; Harper, Graham M.; Brown, Alexander; Hummel, Christian A.

    1996-11-01

    stellar flux plus an interstellar extinction model to the flux-calibrated GHRS data. We find MK = 5.8±0.2 Msun, MB = 4.8±0.2 Msun, RK = 148±3 Rsun, and RB = 4.5±0.3 Rsun for the masses and radii of the ζ Aur stars. We determine the distance to ζ Aur to be 261±3 pc. Additionally, we refine the stellar parameters of the B star secondary presented in the 1995 spectroscopic study of Bennett, Brown, & Linsky. We also determine the effective temperature of the K star primary using values of the bolometric flux, angular diameter, and interstellar extinction derived in this study. The positions of the ζ Aur stars on the theoretical H-R diagram are compared to current evolutionary model tracks, and the resulting good agreement provides a strong check of the internal self-consistency of this analysis and the accuracy of the theoretical models. The ζ Aurigae stars are confirmed to be coeval with an age of 80±15 Myr.

  2. Interaction radii of proton-rich radioactive nuclei at A=60-80

    SciTech Connect

    Lima, G. F.; Lepine-Szily, A.; Lichtenthaler, R.; Villari, A. C. C.; Mittig, W.; Casandjian, J. M.; Lewitowicz, M.; Chartier, M.; Hirata, D.; Angelique, J. C.; Orr, N. A.; Audi, G.; Cunsolo, A.; Foti, A.; Donzeaud, C.; MacCormick, M.; Stephan, C.; Suomijarvi, T.; Tassan-Got, L.; Gillibert, A.

    1998-12-21

    The interaction radii of proton-rich, radioactive {sub 31}Ga, {sub 32}Ge, {sub 33}As, {sub 34}Se, {sub 35}Br isotopes were measured using the direct method. The secondary beams were produced using a {sup 78}Kr primary beam of 73 MeV/nucleon in conjunction with SISSI and the SPEG spectrometers at GANIL. Most elements show reduced radii which vary with N, with a minimum around N=36-38. The experimental reduced radii are compared to theoretical values obtained from Glauber reaction cross-section calculations based on Relativistic Mean Field (RMF) nuclear densities.

  3. Charge radii in macroscopic-microscopic mass models of axial asymmetry

    SciTech Connect

    Iimura, H.; Buchinger, F.

    2007-11-15

    We show that the charge radii of axially asymmetric nuclei calculated in the frame of the finite-range droplet model are in better agreement with measured charge radii when axial asymmetry is taken into account. This improvement is mainly the result of a new set of ground-state quadrupole deformations {beta}{sub 2}, generated when masses are calculated including axial asymmetry, and to a much lesser degree due to the inclusion of the axial asymmetry in the calculation of the charge radii itself.

  4. Upper bound on the radii of black-hole photonspheres

    NASA Astrophysics Data System (ADS)

    Hod, Shahar

    2013-11-01

    One of the most remarkable predictions of the general theory of relativity is the existence of black-hole “photonspheres”, compact null hypersurfaces on which massless particles can orbit the central black hole. We prove that every spherically-symmetric asymptotically flat black-hole spacetime is characterized by a photonsphere whose radius is bounded from above by rγ⩽3M, where M is the total ADM mass of the black-hole spacetime. It is shown that hairy black-hole configurations conform to this upper bound. In particular, the null circular geodesic of the (bald) Schwarzschild black-hole spacetime saturates the bound.

  5. Cathode fall thickness of abnormal glow discharges between parallel-plane electrodes in different radii at low pressure

    SciTech Connect

    Fu, Yangyang; Luo, Haiyun; Zou, Xiaobing; Wang, Xinxin

    2015-02-15

    In order to investigate the influence of electrode radius on the characteristics of cathode fall thickness, experiments of low-pressure (20 Pa ≤ p ≤ 30 Pa) abnormal glow discharge were carried out between parallel-plane electrodes in different radii keeping gap distance unchanged. Axial distributions of light intensity were obtained from the discharge images captured using a Charge Coupled Device camera. The assumption that the position of the negative glow peak coincides with the edge of cathode fall layer was verified based on a two-dimensional model, and the cathode fall thicknesses, d{sub c}, were calculated from the axial distributions of light intensity. It was observed that the position of peak emission shifts closer to the cathode as current or pressure grows. The dependence of cathode fall thickness on the gas pressure and normalized current J/p{sup 2} was presented, and it was found that for discharges between electrodes in large radius the curves of pd{sub c} against J/p{sup 2} were superimposed on each other, however, this phenomenon will not hold for discharges between the smaller electrodes. The reason for this phenomenon is that the transverse diffusions of charged particles are not the same in two gaps between electrodes with different radii.

  6. Radii and Binding Energies in Oxygen Isotopes: A Challenge for Nuclear Forces.

    PubMed

    Lapoux, V; Somà, V; Barbieri, C; Hergert, H; Holt, J D; Stroberg, S R

    2016-07-29

    We present a systematic study of both nuclear radii and binding energies in (even) oxygen isotopes from the valley of stability to the neutron drip line. Both charge and matter radii are compared to state-of-the-art ab initio calculations along with binding energy systematics. Experimental matter radii are obtained through a complete evaluation of the available elastic proton scattering data of oxygen isotopes. We show that, in spite of a good reproduction of binding energies, ab initio calculations with conventional nuclear interactions derived within chiral effective field theory fail to provide a realistic description of charge and matter radii. A novel version of two- and three-nucleon forces leads to considerable improvement of the simultaneous description of the three observables for stable isotopes but shows deficiencies for the most neutron-rich systems. Thus, crucial challenges related to the development of nuclear interactions remain. PMID:27517768

  7. Magnetic structure of the distant geotail from -60 to -220 earth radii - ISEE-3

    NASA Technical Reports Server (NTRS)

    Tsurutani, B. T.; Slavin, J. A.; Smith, E. J.; Okida, R.; Jones, D. E.

    1984-01-01

    ISEE-3 magnetic-field measurements in the region of the geomagnetic tail from -80 to -220 earth radii are reported and discussed. A well-ordered field structure is found, comprising two 7-8-nT lobes separated by a plasma sheet, an embedded neutral sheet with significant By fields, and an intermittent plasma-sheet boundary layer with 5-nT-amplitude (peak-to-peak) electromagnetic waves. The plasma-sheet Bz distribution changes from principally northern orientation near the earth to an approximately equal north-south distribution at 200-220 earth radii. These findings are considered to be in general agreement with magnetic-reconnection models of the magnetosphere, with reconnection either throughout the region observed (in tearing-mode or plasmoid-formation models) or at a constant (about 220-earth-radii) or variable (40-80 to 220-earth-radii) X line (in X-line models).

  8. Radii and Binding Energies in Oxygen Isotopes: A Challenge for Nuclear Forces

    NASA Astrophysics Data System (ADS)

    Lapoux, V.; Somà, V.; Barbieri, C.; Hergert, H.; Holt, J. D.; Stroberg, S. R.

    2016-07-01

    We present a systematic study of both nuclear radii and binding energies in (even) oxygen isotopes from the valley of stability to the neutron drip line. Both charge and matter radii are compared to state-of-the-art ab initio calculations along with binding energy systematics. Experimental matter radii are obtained through a complete evaluation of the available elastic proton scattering data of oxygen isotopes. We show that, in spite of a good reproduction of binding energies, ab initio calculations with conventional nuclear interactions derived within chiral effective field theory fail to provide a realistic description of charge and matter radii. A novel version of two- and three-nucleon forces leads to considerable improvement of the simultaneous description of the three observables for stable isotopes but shows deficiencies for the most neutron-rich systems. Thus, crucial challenges related to the development of nuclear interactions remain.

  9. Atomic Structures of Molecules Based on Additivity of Atomic and/or Ionic Radii (abstract)

    NASA Astrophysics Data System (ADS)

    Heyrovska, Raji; Narayan, Sara

    2009-04-01

    We have shown in recent years that interatomic and interionic distances are sums of the radii of the adjacent atoms or ions. Many examples are provided and it is shown how the experimental bond lengths agree with the radii sums. The examples include inorganic compounds such as alkali halides, metal hydrides, and graphene; organic compounds such as aliphatic and aromatic compounds; and biochemical compounds such as nucleic acids, amino acids, caffeine-related compounds, and vitamins.

  10. Eccentric ringlet in the maxwell gap at 1.45 saturn radii: multi-instrument voyager observations.

    PubMed

    Esposito, L W; Borderies, N; Goldreich, P; Cuzzi, J N; Holberg, J B; Lane, A L; Pomphrey, R B; Terrile, R J; Lissauer, J J; Marouf, E A; Tyler, G L

    1983-10-01

    The Voyager spacecraft observed a narrow, eccentric ringlet in the Maxwell gap (1.45 Saturn radii) in Saturn's rings. Intercomparison of the Voyager imaging, photopolarimeter, ultraviolet spectrometer, and radio science observations yields results not available from individual observations. The width of the ringlet varies from about 30 to about 100 kilometers, its edges are sharp on a radial scale < 1 kilometer, and its opacity exhibits a double peak near the center. The shape and width of the ringlet are consistent with a set of uniformly precessing, confocal ellipses with foci at Saturn's center of mass. The ringlet precesses as a unit at a rate consistent with the known dynamical oblateness of Saturn; the lack of differential precession across the ringlet yields a ringlet mass of about 5 x 10(18) grams. The ratio of surface mass density to particle cross-sectional area is about five times smaller than values obtained elsewhere in the Saturn ring system, indicating a relatively larger fraction of small particles. Also, comparison of the measured transmission of the ringlet at radio, visible, and ultraviolet wavelengths indicates that about half of the total extinction is due to particles smaller than 1 centimeter in radius, in contrast even with nearby regions of the C ring. However, the color and brightness of the ringlet material are not measurably different from those of nearby C ring particles. We find this ringlet is similar to several of the rings of Uranus. PMID:17810092

  11. On the critical radii for ramp induced shock wave and laminar boundary layer interaction

    NASA Astrophysics Data System (ADS)

    John, Bibin; Kulkarni, Vinayak

    2013-11-01

    The shock wave and laminar boundary layer interaction is classical example of viscous and inviscid interaction. All the characteristic features of this interaction like separation length, separation and reattachment locations, upstream influence etc. are dependent on the leading edge bluntness. Upstream over pressure region and interaction of entropy layer with boundary layer alter this dynamics in the presence of blunt leading edge. Two critical radii corresponding to maximum separation size and separation length equal to reference sharp leading edge case are observed for this interaction during the present numerical studies. Freestream Mach number, wall temperature and freestream stagnation enthalpy are the governing parameters for the two critical radii for given configuration. Numerical simulations are then carried out to understand the effect of these parameters on the magnitude of the critical radii. Entropy layer swallowing by boundary layer and extension of over pressure region are reconsidered for alterations in these radii. Present studies are found very useful in devising mechanism for estimation of critical radii and as well for incorporating the amendment in the same due to change in governing parameters.

  12. Interaction radii of proton-rich radioactive nuclei at A=60{endash}80

    SciTech Connect

    Lima, G.F.; Lepine-Szily, A.; Villari, A.C.; Lichtenthaler, R.; Villari, A.C.; Mittig, W.; Chartier, M.; Casandjian, J.M.; Lewitowicz, M.; Ostrowski, A.N.; Hirata, D.; Angelique, J.C.; Orr, N.A.; Audi, G.; Cunsolo, A.; Foti, A.; Donzeaud, C.; MacCormick, M.; Stephan, C.; Suomijarvi, T.; Tassan-Got, L.; Gillibert, A.; Chartier, M.; Morrissey, D.J.; Sherrill, B.M.; Ostrowski, A.N.; Vieira, D.J.; Wouters, J.M.

    1998-12-01

    The interaction radii of proton-rich, radioactive {sub 31}Ga,thinsp{sub 32}Ge,thinsp{sub 33}As,thinsp{sub 34}Se,thinsp{sub 35}Br isotopes were measured using the direct method. The secondary beams were produced using a {sup 78}Kr primary beam of 73 MeV/nucleon in conjunction with SISSI and the SPEG spectrometers at GANIL. Most elements show reduced radii which vary with N, with a minimum around N=36{endash}38. The experimental reduced radii are compared to theoretical values obtained from Glauber reaction cross-section calculations based on Relativistic Mean Field (RMF) nuclear densities. {copyright} {ital 1998 American Institute of Physics.}

  13. Energy losses in thermally cycled optical fibers constrained in small bend radii

    SciTech Connect

    Guild, Eric; Morelli, Gregg

    2012-09-23

    High energy laser pulses were fired into a 365μm diameter fiber optic cable constrained in small radii of curvature bends, resulting in a catastrophic failure. Q-switched laser pulses from a flashlamp pumped, Nd:YAG laser were injected into the cables, and the spatial intensity profile at the exit face of the fiber was observed using an infrared camera. The transmission of the radiation through the tight radii resulted in an asymmetric intensity profile with one half of the fiber core having a higher peak-to-average energy distribution. Prior to testing, the cables were thermally conditioned while constrained in the small radii of curvature bends. Single-bend, double-bend, and U-shaped eometries were tested to characterize various cable routing scenarios.

  14. A reflection ansatz for surfaces with electrically small radii of curvature

    NASA Technical Reports Server (NTRS)

    Dominek, Allen K.; Peters, Leon, Jr.; Burnside, Walter D.

    1987-01-01

    Uniform reflection coefficients are developed for two- and three-dimensional, edge-like, perfectly conducting surfaces in the deep lit region. The uniformity is with respect to the electrical size of the radii of curvature at the surface's specular point. This uniformity allows one to physically interpret the reflected field from a smooth surface as one of the radii of curvature approaches zero as a diffracted field. The coefficients are heuristically generated from the exact scattered field for a two dimensional parabolic cylinder with plane wave illumination. The significant variables in this solution are the radii of curvature at the specular point and the distance between the specular point and the incident shadow boundaries in the principal planes. The field prediction accuracy of these reflection cofficients are critically examined through comparisons with reflected fields extracted from scattered fields of canonical surfaces.

  15. Development of Experiments to Measure D and 4He Charge Radii with Elastic Electron Scattering Method

    NASA Astrophysics Data System (ADS)

    Saudi, Sheikh

    Charge radii are one of the important physical characteristics to understand the electromagnetic structure of nuclei. For light nuclei, they are playing a more critical role to better understand the nucleon-nucleon interaction and test the existing models for bound states. Recent measurements of proton radius, done with muonic hydrogen spectroscopy, showed about 7 standard deviation lower than previous experimental results. This discrepancy triggered the so called "Proton Radius Puzzle" in physics world. Several groups are preparing to perform new experiments to extract the proton radius with better precision and model independent methods. It is equally important to perform new experiments for light nuclei, like deuteron (D) and helium-4 (4He), to verify the existing results for their radii. In this thesis work, we have developed an experimental method based on coincidence detection of the scattered electrons and recoiled light nuclei to measure the charge radii of deuteron and helium-4 with high accuracy.

  16. A new determination of radii and limb parameters for Pluto and Charon from mutual event lightcurves

    NASA Technical Reports Server (NTRS)

    Young, Eliot F.; Binzel, Richard P.

    1994-01-01

    Over the past several years Pluto-Charon mutual events have yielded progressively more accurate estimates of Charon's orbital elements and the radii of Pluto and Charon (e.g., Buie, Tholen, and Horne, 1992). Analysis of the 1988 stellar occultation by Pluto indicates a radius for Pluto that is about 4%, or 50 km, larger than the mutual event radius of 1151 km. One possible explanation for the discrepancy is that the mutual event modeling treats Pluto and Charon as uniformly bright disks. If they are limb-darkened, the mutual event fits could underestimate their radii. In this paper we use an independent mutual event data set (Young and Binzel, 1992) to fit for Pluto and Charon's radii in a manner independent of either object's limb profile or albedo distribution. Our least-squares solution indicates that Pluto's radius is 1164 +/- 22.9 km and Charon's radius is 621 +/- 20.6 km.

  17. EFFECT OF UNCERTAINTIES IN STELLAR MODEL PARAMETERS ON ESTIMATED MASSES AND RADII OF SINGLE STARS

    SciTech Connect

    Basu, Sarbani; Verner, Graham A.; Chaplin, William J.; Elsworth, Yvonne E-mail: gav@bison.ph.bham.ac.uk E-mail: y.p.elsworth@bham.ac.uk

    2012-02-10

    Accurate and precise values of radii and masses of stars are needed to correctly estimate properties of extrasolar planets. We examine the effect of uncertainties in stellar model parameters on estimates of the masses, radii, and average densities of solar-type stars. We find that in the absence of seismic data on solar-like oscillations, stellar masses can be determined to a greater accuracy than either stellar radii or densities; but to get reasonably accurate results the effective temperature, log g, and metallicity must be measured to high precision. When seismic data are available, stellar density is the most well-determined property, followed by radius, with mass the least well-determined property. Uncertainties in stellar convection, quantified in terms of uncertainties in the value of the mixing length parameter, cause the most significant errors in the estimates of stellar properties.

  18. The motion and magnetic structure of the plasma sheet near 30 earth radii

    NASA Technical Reports Server (NTRS)

    Bowling, S. B.; Wolf, R. A.

    1974-01-01

    Data taken by the NASA-GSFC magnetometer aboard the Explorer 34 satellite are analyzed in an effort to ascertain the average motion and magnetic field structure of the plasma sheet near 30 earth radii. It is found that the flapping motion of the plasma sheet in the solar ecliptic Z-coordinate is characterized by a typical speed of 90 km/sec and an amplitude of plus or minus 2 earth radii. Results suggest that there exists a layer of nearly uniform cross-tail current density in the central region of the plasma sheet approximately 2.3-2.6 earth radii thick within which the solar-magnetospheric X-component of the magnetic field changes from 10 gamma to -10 gamma.

  19. The effect of starspots on the radii of low-mass pre-main-sequence stars

    NASA Astrophysics Data System (ADS)

    Jackson, R. J.; Jeffries, R. D.

    2014-07-01

    A polytropic model is used to investigate the effects of dark photospheric spots on the evolution and radii of magnetically active, low-mass (M < 0.5 M⊙), pre-main-sequence (PMS) stars. Spots slow the contraction along Hayashi tracks and inflate the radii of PMS stars by a factor of (1 - β)-N compared to unspotted stars of the same luminosity, where β is the equivalent covering fraction of dark starspots and N ≃ 0.45 ± 0.05. This is a much stronger inflation than predicted by Spruit & Weiss for main-sequence stars with the same β, where N ˜ 0.2-0.3. These models have been compared to radii determined for very magnetically active K- and M-dwarfs in the young Pleiades and NGC 2516 clusters, and the radii of tidally locked, low-mass eclipsing binary components. The binary components and zero-age main-sequence K-dwarfs have radii inflated by ˜10 per cent compared to an empirical radius-luminosity relation that is defined by magnetically inactive field dwarfs with interferometrically measured radii; low-mass M-type PMS stars, that are still on their Hayashi tracks, are inflated by up to ˜40 per cent. If this were attributable to starspots alone, we estimate that an effective spot coverage of 0.35 < β < 0.51 is required. Alternatively, global inhibition of convective flux transport by dynamo-generated fields may play a role. However, we find greater consistency with the starspot models when comparing the loci of active young stars and inactive field stars in colour-magnitude diagrams, particularly for the highly inflated PMS stars, where the large, uniform temperature reduction required in globally inhibited convection models would cause the stars to be much redder than observed.

  20. Nuclear moments and charge radii of neutron-deficient francium isotopes and isomers

    NASA Astrophysics Data System (ADS)

    Voss, A.; Buchinger, F.; Cheal, B.; Crawford, J. E.; Dilling, J.; Kortelainen, M.; Kwiatkowski, A. A.; Leary, A.; Levy, C. D. P.; Mooshammer, F.; Ojeda, M. L.; Pearson, M. R.; Procter, T. J.; Tamimi, W. Al

    2015-04-01

    Collinear laser fluorescence spectroscopy has been performed on the ground and isomeric states of Fr,206204 in order to determine their spins, nuclear moments, and changes in mean-squared charge radii. A new experimental technique has been developed as part of this work which much enhances the data collection rate while maintaining the high resolution. This has permitted the extension of this study to the two isomeric states in each nucleus. The investigation of nuclear g factors and mean-squared charge radii indicates that the neutron-deficient Fr isotopes lie in a transitional region from spherical towards more collective structures.

  1. Proton Distribution Radii of 12-19C Illuminate Features of Neutron Halos

    DOE PAGESBeta

    Kanungo, R.; Horiuchi, W.; Hagen, Gaute; Jansen, Gustav R.; Navratil, Petr; Ameil, F.; Atkinson, J.; Ayyad, Y.; Cortina-Gil, D.; Dillmann, I.; et al

    2016-09-02

    We report proton radii of 12-19C densities derived from first accurate charge changing cross section measurements at 900A MeV with a carbon target. A thick neutron surface evolves from ~0.5 fm in 15C to ~1 fm in 19C. Also, the halo radius in 19C is found to be 6.4±0.7 fm as large as 11Li. Ab initio calculations based on chiral nucleon-nucleon and three-nucleon forces reproduce the radii well.

  2. Responses of articular and epiphyseal cartilage zones of developing avian radii to estrone treatment and a 2-G environment

    NASA Technical Reports Server (NTRS)

    Negulesco, J. A.; Kossler, T.

    1978-01-01

    Histological measurements of radii from chickens exposed to estrone and hypergravity are reported. Female chicks at two weeks post-hatch were maintained for two weeks at earth gravity or 2 G with daily injections of 0.2 or 0.4 mg estrone. Animals were sacrificed after the last injection, and the radii were processed by described histological techniques. The results suggest that proximal and distal epiphyses of developing radii show different morphological responses to estrone and hypergravity.

  3. ESTIMATION OF PARTICLE SIZES FOR A RANGE OF NARROW SIZE DISTRIBUTIONS OF NATURAL AND SUSPENDED IN WATER USING MULTIFREQUENCY ACOUSTIC BACKSCATTER

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The measurement of particle size using multiple, megahertz range acoustic frequencies has been focused on particles with radii of 50'm -150'm. The present study seeks to extend the applicability of the technique to particles with radii ranging from 50'm -425'm. A single acoustic transducer, transmit...

  4. Investigation of Possible Electromagnetic Disturbances caused by Spacecraft-Plasma Interactions at 4 Radii

    NASA Technical Reports Server (NTRS)

    Okada, M.; Tsurutani, B. T.; Goldstein, G. E.; Matsumoto, H.; Brinca, A. L.; Kellogg, P. J.

    1995-01-01

    The proposed Small Solar Probe mission features a close approach to the sun with a perihelion of 4 radii. Carbon molecules emitted from the spacecraft's heat shield will become ionized by electron impact and photoionization. The newly created ions and electrons may generate electromagnetic and electrostatic plasma waves which are possible sources of interference with in-situ plasma measurements.

  5. Determination of mechanical properties of excised dog radii from lateral vibration experiments

    NASA Technical Reports Server (NTRS)

    Thompson, G. A.; Anliker, M.; Young, D. R.

    1973-01-01

    Experimental data which can be used as a guideline in developing a mathematical model for lateral vibrations of whole bone are reported. The study used wet and dry dog radii mounted in a cantilever configuration. Data are also given on the mechanical, geometric, and viscoelastic properties of bones.

  6. Absolute masses and radii determination in multiplanetary systems without stellar models

    NASA Astrophysics Data System (ADS)

    Almenara, J. M.; Díaz, R. F.; Mardling, R.; Barros, S. C. C.; Damiani, C.; Bruno, G.; Bonfils, X.; Deleuil, M.

    2015-11-01

    The masses and radii of extrasolar planets are key observables for understanding their interior, formation and evolution. While transit photometry and Doppler spectroscopy are used to measure the radii and masses respectively of planets relative to those of their host star, estimates for the true values of these quantities rely on theoretical models of the host star which are known to suffer from systematic differences with observations. When a system is composed of more than two bodies, extra information is contained in the transit photometry and radial velocity data. Velocity information (finite speed-of-light, Doppler) is needed to break the Newtonian MR-3 degeneracy. We performed a photodynamical modelling of the two-planet transiting system Kepler-117 using all photometric and spectroscopic data available. We demonstrate how absolute masses and radii of single-star planetary systems can be obtained without resorting to stellar models. Limited by the precision of available radial velocities (38 m s-1), we achieve accuracies of 20 per cent in the radii and 70 per cent in the masses, while simulated 1 m s-1 precision radial velocities lower these to 1 per cent for the radii and 2 per cent for the masses. Since transiting multiplanet systems are common, this technique can be used to measure precisely the mass and radius of a large sample of stars and planets. We anticipate these measurements will become common when the TESS and PLATO mission provide high-precision light curves of a large sample of bright stars. These determinations will improve our knowledge about stars and planets, and provide strong constraints on theoretical models.

  7. Charge radii and nuclear moments of neutron-deficient potassium isotopes

    NASA Astrophysics Data System (ADS)

    Minamisono, K.; Barquest, B. R.; Bollen, G.; Hughes, M.; Strum, R.; Tarazona, D.; Asberry, H. B.; Cooper, K.; Hammerton, K.; Klose, A.; Mantica, P. F.; Morrissey, D. J.; Geppert, Ch.; Harris, J.; Ringle, R.; Rodriguez, J. A.; Rossi, D. M.; Ryder, C. A.; Smith, A.; Schwarz, S.; Sumithrarachchi, C.

    2014-09-01

    The monotonic change of charge radii of K isotopes across N = 20 suggests a reduction of the shell gap. A systematic study of the charge radii and ground state magnetic and quadrupole moments of neutron-deficient 35-37K isotopes is underway at the BEam COoling and LAser spectroscopy (BECOLA) facility at NSCL/MSU to investigate the anomalous trend in charge radii. The K isotopes were produced by fragmentation of a 40Ca beam, thermalized in a linear gas cell, extracted at an energy of 30 keV, and transported to BECOLA. The K ion beam was cooled and bunched, and neutralized in a Na vapor cell. Laser-induced fluorescence was detected as a function of the Doppler-tuned laser frequency and time relative to the release of the beam bunch. The beta-NMR technique was used to determine ground-state nuclear moments, where hyperfine splittings are too small to resolve using collinear laser spectroscopy. The monotonic change of charge radii of K isotopes across N = 20 suggests a reduction of the shell gap. A systematic study of the charge radii and ground state magnetic and quadrupole moments of neutron-deficient 35-37K isotopes is underway at the BEam COoling and LAser spectroscopy (BECOLA) facility at NSCL/MSU to investigate the anomalous trend in charge radii. The K isotopes were produced by fragmentation of a 40Ca beam, thermalized in a linear gas cell, extracted at an energy of 30 keV, and transported to BECOLA. The K ion beam was cooled and bunched, and neutralized in a Na vapor cell. Laser-induced fluorescence was detected as a function of the Doppler-tuned laser frequency and time relative to the release of the beam bunch. The beta-NMR technique was used to determine ground-state nuclear moments, where hyperfine splittings are too small to resolve using collinear laser spectroscopy. This work was supported in part by NSF Grant No. PHY-11-02511.

  8. Influence of piezoceramic to fused silica plate thickness on the radii of curvature of piezoelectric bimorph mirror

    NASA Astrophysics Data System (ADS)

    Libu, M.; Susanth, S.; Vasanthakumari, K. G.; Dileep Kumar, C. J.; Raghu, N.

    2012-01-01

    Piezoelectric based bimorph mirrors (PBM) find extensive use in focusing of x-ray beams. Many optical instruments require use of PBM whose radii of curvature can be tuned precisely. The 100 mm and 300 mm PBMs were fabricated with varying piezoelectric to fused silica plate thicknesses. The radii of curvature of free standing mirrors were measured as a function of voltage and it was found to decrease with increasing voltage. For a given piezoelectric plate thickness, as the fused silica thickness increases, the radii of curvature was found to increase owing to increase in stiffness of the mirror. On the other hand, for a given fused silica plate thickness, when the piezoelectric plate thickness is increased, the radii of curvature are decreased for a given electric field, due to increase in generated force. This study brings out the influence of piezoceramic to fused silica plate thickness on the radii of curvature of PBM.

  9. Counter-streaming electrons at the geomagnetic equator near 9 earth radii

    NASA Technical Reports Server (NTRS)

    Klumpar, D. M.; Quinn, J. M.; Shelley, E. G.

    1988-01-01

    AMPTE/CEE observations are used to study short-lived, highly anisotropic electron distributions in the region of the equatorial magnetosphere bewtween 6.6 earth radii and the CCE apogee at 8.8 earth radii. Intense bursts of highly collimated counterstreaming electrons were observed at keV energies with durations of a few tens of seconds to a few minutes near the geomagnetic equator on L-shells that intersect the high-latitude ionosphere in the region normally associated with the auroral zone. It is found that the counterstreaming electrons at energies below the peak energy are accompanied by simultaneous deep depressions of the locally mirroring fluxes. It is suggested that these equatorial electrons may result from the release of auroral electrons trapped beneath the auroral accelerating potentials at lower altitudes along the same magnetic flux tubes.

  10. Masses And Radii Of Neutron Stars Measured From Thermonuclear X-ray Bursts

    NASA Astrophysics Data System (ADS)

    Guver, Tolga; Ozel, F.

    2011-09-01

    Low mass X-ray binaries that show thermonuclear bursts are ideal targets for constraining the equation of state of neutron star matter. The analysis of the time resolved, high count rate X-ray spectra allow a measurement of the Eddington limits and the apparent radii of neutron stars. Combined with an independent distance estimate, these spectroscopic quantities lead to the measurement of neutron star masses and radii. I will discuss the results of the application of this method to a number of X-ray binaries including EXO 1745-248, 4U 1820-30, 4U 1608-52,KS 1731-260, and SAX J1748.9-2021. I will also present the results from a comprehensive analysis of the entire RXTE archive of X-ray burst observations, which allows for a better quantification of the systematic uncertainties in these measurements.

  11. Measuring The Distances, Masses, and Radii of Neutron Stars In X-ray Binaries

    NASA Astrophysics Data System (ADS)

    Guver, Tolga; Ozel, F.; Cabrera-Lavers, A.

    2010-03-01

    Low mass X-ray binaries that have independent distance measurements and show thermonuclear X-ray bursts are ideal sources for constraining the equation of state of neutron star matter. I will introduce our program to systematically measure the distances, masses, and radii of neutron stars in such binaries. We utilize high energy resolution X-ray spectra to measure the ISM column densities to these sources as well as time resolved, high count rate X-ray spectra to study their bursts. I will discuss in detail how the combination of these observations have led to the measurement of the masses and radii of the neutron stars in the low mass X-ray binaries EXO 1745-248, 4U 1608-52, and 4U 1820-30.

  12. Nuclear radii calculations in various theoretical approaches for nucleus-nucleus interactions

    SciTech Connect

    Merino, C.; Novikov, I. S.; Shabelski, Yu.

    2009-12-15

    The information about sizes and nuclear density distributions in unstable (radioactive) nuclei is usually extracted from the data on interaction of radioactive nuclear beams with a nuclear target. We show that in the case of nucleus-nucleus collisions the values of the parameters depend somewhat strongly on the considered theoretical approach and on the assumption about the parametrization of the nuclear density distribution. The obtained values of root-mean-square radii (R{sub rms}) for stable nuclei with atomic weights A=12-40 vary by approximately 0.1 fm when calculated in the optical approximation, in the rigid target approximation, and using the exact expression of the Glauber theory. We present several examples of R{sub rms} radii calculations using these three theoretical approaches and compare these results with the data obtained from electron-nucleus scattering.

  13. Return stroke speed of cloud-to-ground lightning estimated from elve hole radii

    NASA Astrophysics Data System (ADS)

    Blaes, P. R.; Marshall, R. A.; Inan, U. S.

    2014-12-01

    We present the first measurements of the lightning return stroke speed that directly relate to the current return stroke, as opposed to its optical manifestation. The shape of elves is determined by the electromagnetic pulse (EMP) radiation pattern at D region altitudes, which is in turn controlled by the geometry and current propagation properties of the return stroke channel. In particular, numerical simulation of the EMP-ionosphere interaction shows a strong relationship between the elve "hole" radius and the current return stroke speed. The hole radii are measured from a data set of 55 elves observed with the PIPER photometer. Using these radii observations in conjunction with numerical simulations of the EMP, we perform Bayesian inference to estimate the distribution of return stroke speeds. The results show a maximum a posteriori probability return stroke speed estimate of 0.64c for elve producing lightning.

  14. Cu charge radii reveal a weak sub-shell effect at N =40

    NASA Astrophysics Data System (ADS)

    Bissell, M. L.; Carette, T.; Flanagan, K. T.; Vingerhoets, P.; Billowes, J.; Blaum, K.; Cheal, B.; Fritzsche, S.; Godefroid, M.; Kowalska, M.; Krämer, J.; Neugart, R.; Neyens, G.; Nörtershäuser, W.; Yordanov, D. T.

    2016-06-01

    Collinear laser spectroscopy on Cu-7558 isotopes was performed at the CERN-ISOLDE radioactive ion beam facility. In this paper we report on the isotope shifts obtained from these measurements. State-of-the-art atomic physics calculations have been undertaken in order to determine the changes in mean-square charge radii δ A ,A' from the observed isotope shifts. A local minimum is observed in these radii differences at N =40 , providing evidence for a weak N =40 sub-shell effect. However, comparison of δ A ,A' with a droplet model prediction including static deformation deduced from the spectroscopic quadrupole moments, points to the persistence of correlations at N =40 .

  15. Quiet time magnetospheric field depression at 2.3-3.6 earth radii.

    NASA Technical Reports Server (NTRS)

    Sugiura, M.

    1973-01-01

    Flux gate magnetometer data from OGO 5 are presented that establish the existence of large field depressions under conditions of varying degree of disturbance at distances ranging from 2.3 to 3.6 earth radii at all local times. For this study, flux gate data obtained near perigee during the period of approximately one year from Jan. 21, 1969, to Feb. 23, 1970, were used.

  16. Charge radii of odd-A191-211Po isotopes

    NASA Astrophysics Data System (ADS)

    Seliverstov, M. D.; Cocolios, T. E.; Dexters, W.; Andreyev, A. N.; Antalic, S.; Barzakh, A. E.; Bastin, B.; Büscher, J.; Darby, I. G.; Fedorov, D. V.; Fedoseyev, V. N.; Flanagan, K. T.; Franchoo, S.; Fritzsche, S.; Huber, G.; Huyse, M.; Keupers, M.; Köster, U.; Kudryavtsev, Yu.; Marsh, B. A.; Molkanov, P. L.; Page, R. D.; Sjødin, A. M.; Stefan, I.; Van de Walle, J.; Van Duppen, P.; Venhart, M.; Zemlyanoy, S. G.

    2013-02-01

    Isotope shifts have been measured for the odd-A polonium isotopes 191-211Po and changes in the nuclear mean square charge radii δ have been deduced. The measurements were performed at CERN-ISOLDE using the in-source resonance-ionization spectroscopy technique. The combined analysis of these data and our recent results for even-A polonium isotopes indicates an onset of deformation already at 197,198Po, when going away from stability. This is significantly earlier than was suggested by previous theoretical and experimental studies of the polonium isotopes. Moreover and in contrast to the mercury isotopes, where a strong odd-even staggering of the charge radii of the ground states was observed by approaching the neutron mid-shell at N = 104, no such effect is present in polonium down to 191Po. Consequently the charge radii of both isomeric and ground states of the odd-A polonium isotopes follow the same trend as the even-A isotopes.

  17. Determination of the capture radii of magnetite bearing hydroxide flocs in magnetic filtration

    SciTech Connect

    Franz, M.; Franzreb, M.

    1998-11-01

    Magnetic filtration may be applied in water technology for the separation of flocs which are formed in a flocculation tank together with magnetite as an additive. The capture radius is an important mathematical quantity to calculate the performance of such filters in advance. Thus, the capture radii of magnetite bearing copper hydroxide flocs were measured with a direct visual evaluation of the floc trajectories in the neighborhood of a single magnetized wire. For this purpose, an experimental setup was assembled, which allowed the observation and the measurement of the trajectories. With the image processing system used, it was possible to observe flocs larger than 30 {micro}m and the flow velocity was limited to a maximum value of 20 mm/s. Capture radii were calculated by the established single-wire theory under the assumption of potential and creeping flow conditions. It has been proved that further information on the solids content of the flocs, which strongly influences the floc susceptibility, was necessary to obtain an agreement between the experimental data and the theoretical predictions. By introducing a floc size dependent solids content into the single-wire theory, measured by means of sedimentation analysis, an accurate description of the observed capture radii was possible.

  18. Which processes shape stellar population gradients of massive galaxies at large radii?

    NASA Astrophysics Data System (ADS)

    Hirschmann, Michaela

    2016-08-01

    We investigate the differential impact of physical mechanisms, mergers (stellar accretion) and internal energetic phenomena, on the evolution of stellar population gradients in massive, present-day galaxies employing a set of high-resolution, cosmological zoom simulations. We demonstrate that negative metallicity and color gradients at large radii (>2Reff) originate from the accretion of metal-poor stellar systems. At larger radii, galaxies become typically more dominated by stars accreted from satellite galaxies in major and minor mergers. However, only strong galactic winds can sufficiently reduce the metallicity content of the accreted stars to realistically steepen the outer metallicity and colour gradients in agreement with present-day observations. In contrast, the gradients of the models without winds are inconsistent with observations (too flat). In the wind model, colour and metallicity gradients are significantly steeper for systems which have accreted stars in minor mergers, while galaxies with major mergers have relatively flat gradients, confirming previous results. This analysis greatly highlights the importance of both energetic processes and merger events for stellar population properties of massive galaxies at large radii. Our results are expected to significantly contribute to the interpretation of current and up-coming IFU surveys (like MaNGA and Califa), which in turn can help to better constrain still uncertain models for energetic processes in simulations.

  19. Larger Planet Radii Inferred from Stellar "Flicker" Brightness Variations of Bright Planet-host Stars

    NASA Astrophysics Data System (ADS)

    Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua

    2014-06-01

    Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, log g. Recent work has demonstrated that the short-timescale brightness variations ("flicker") of stars can be used to measure log g to a high accuracy of ~0.1-0.2 dex. Here, we use flicker measurements of 289 bright (Kepmag < 13) candidate planet-hosting stars with T eff = 4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, Malmquist bias contaminates the stellar sample with evolved stars: nearly 50% of the bright planet-host stars are subgiants. As a result, the stellar radii, and hence the radii of the planets orbiting these stars, are on average 20%-30% larger than previous measurements had suggested.

  20. LARGER PLANET RADII INFERRED FROM STELLAR ''FLICKER'' BRIGHTNESS VARIATIONS OF BRIGHT PLANET-HOST STARS

    SciTech Connect

    Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua

    2014-06-10

    Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, log g. Recent work has demonstrated that the short-timescale brightness variations ({sup f}licker{sup )} of stars can be used to measure log g to a high accuracy of ∼0.1-0.2 dex. Here, we use flicker measurements of 289 bright (Kepmag < 13) candidate planet-hosting stars with T {sub eff} = 4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, Malmquist bias contaminates the stellar sample with evolved stars: nearly 50% of the bright planet-host stars are subgiants. As a result, the stellar radii, and hence the radii of the planets orbiting these stars, are on average 20%-30% larger than previous measurements had suggested.

  1. A photometric and radial velocity study of six southern Cepheids. II - Binarity, radii, luminosities, and masses

    NASA Astrophysics Data System (ADS)

    Coulson, I. M.; Caldwell, J. A. R.; Gieren, W. P.

    1986-04-01

    The data now available for the Galactic Cepheids AQ Car (period = 9.77 days), XX Cen (10.95 days), XY Car (12.44 days), TT Aql (13.75 days), XX Car (15.71 days), and XZ Car (16.65 days) are analyzed for binarity, radius, luminosity, and mass. There is weak evidence only for binarity of XX Cen, XX Car, and XZ Car, and it is concluded that all six Cepheids may be considered to be single. The new velocity data for XX Cen suggest that it may belong to a binary system with an orbital period of 800 d. The radii are derived by an improved version of the Baade-Wesselink technique and are found to depend upon the color index used to define the surface brightness. The V - I radii, for instance, are 20-25 percent larger than the B - V radii, and it is suggested that the Cepheid mass discrepancy problem may be alleviated by use of appropriate colors in the B - W radius solutions.

  2. The Radii and Oblateness of Pluto and Charon: Preliminary Results from the 2015 New Horizons Flyby

    NASA Astrophysics Data System (ADS)

    Lisse, Carey M.; Nimmo, Francis; McKinnon, William B.; Umurhan, Orkan M.; Buie, Marc W.; Lauer, Tod R.; Roberts, James H.; Stern, S. Alan; Weaver, Hal A.; Young, Leslie A.; Ennico-Smith, Kimberly; Olkin, Cathy B.

    2015-11-01

    We present preliminary results for the radii and oblateness of Pluto and Charon. Accurate determinations of the mean radii of Pluto and Charon are important for establishing their densities and bulk composition. A fossil bulge, if present, would place constraints on the thermal and orbital evolution of these bodies [1,2]. The New Horizons LORRI imaging system [3] has provided global images of Pluto and Charon, with best resolutions of 3.8 and 2.3 km/pix, respectively. Three separate approaches have been used to determine mean radii and oblateness from the images, two using a threshold DN value [4,5] and one using a maximum gradient method. These approaches were validated using synthetic images having a range of photometric functions. Tradeoffs between the limb center location and the derived shape in individual images can be reduced by combining limb pixel locations obtained from different imaged rotational phases.This work was supported by NASA's New Horizons project.[1] Robuchon & Nimmo, Icarus 216, 426, 2011. [2] McKinnon & Singer, DPS 46, abs. no. 419.07, 2014. [3] Cheng et al., SSR 140, 189, 2008. [4] Dermott & Thomas, Icarus 73, 25, 1988. [5] Thomason & Nimmo, LPSC 46, abs. no. 1462, 2015.

  3. Effects on the geomagnetic tail at 60 earth radii of the geomagnetic storm of April 9, 1971.

    NASA Technical Reports Server (NTRS)

    Burke, W. J.; Rich, F. J.; Reasoner, D. L.; Colburn, D. S.; Goldstein, B. E.

    1973-01-01

    A geomagnetic storm beginning with an sc occurred on Apr. 9, 1971. During the storm the charged particle lunar environment experiment at the Apollo 14 site, the solar wind spectrometer experiment at the Apollo 12 site, and the Ames magnetometers on Explorer 35 took data in the magnetosheath, at the magnetopause, in the plasma sheet, and in the high-latitude geomagnetic tail. The MIT Faraday cup and Ames magnetometers on board Explorer 33 monitored the solar wind. The data show that the storm was caused by a corotating tangential discontinuity in the solar wind, the magnetopause position is strongly dependent on the attack angle of the solar wind, and the tail field strength was indirectly measured to increase from 10 to 14 gamma after the sc. During the main phase the field strength in the tail was observed to increase to between 28 and 34 gamma. This increase is consistent with a thermal and magnetic compression of the tail radius from about 26 to about 16 earth radii.

  4. The mass and angular momentum distribution of simulated massive early-type galaxies to large radii

    NASA Astrophysics Data System (ADS)

    Wu, Xufen; Gerhard, Ortwin; Naab, Thorsten; Oser, Ludwig; Martinez-Valpuesta, Inma; Hilz, Michael; Churazov, Eugene; Lyskova, Natalya

    2014-03-01

    We study the dark and luminous mass distributions, circular velocity curves (CVCs), line-of-sight kinematics and angular momenta for a sample of 42 cosmological zoom simulations of galaxies with stellar masses from 2.0 × 1010 to 3.4 × 1011 M⊙ h-1. Using a temporal smoothing technique, we are able to reach large radii. We find the following. The dark matter halo density profiles outside a few kpc follow simple power-law models, with flat dark matter CVCs for lower mass systems, and rising CVCs for high-mass haloes. The projected stellar density distributions at large radii can be fitted by Sérsic functions with n ≳ 10, larger than for typical early-type galaxies (ETGs). The massive systems have nearly flat total (luminous plus dark matter) CVCs at large radii, while the less massive systems have mildly decreasing CVCs. The slope of the circular velocity at large radii correlates with circular velocity itself. The dark matter fractions within the projected stellar half-mass radius Re are in the range 15-30 per cent and increase to 40-65 per cent at 5Re. Larger and more massive galaxies have higher dark matter fractions. The fractions and trends with mass and size are in agreement with observational estimates, even though the stellar-to-total mass ratio is ˜2-3 times higher than estimated for ETGs. The short axes of simulated galaxies and their host dark matter haloes are well aligned and their short-to-long axis ratios are correlated. The stellar root mean square velocity vrms(R) profiles are slowly declining, in agreement with planetary nebulae observations in the outer haloes of most ETGs. The line-of-sight velocity fields {bar{v}} show that rotation properties at small and large radii are correlated. Most radial profiles for the cumulative specific angular momentum parameter λ(R) are nearly

  5. Radii of atomic ions determined from diatomic ion-He bond lengths.

    PubMed

    Wright, Timothy G; Breckenridge, W H

    2010-03-11

    We propose a new definition of the effective radius of an atomic ion: the bond distance (R(e)) of the ion/He diatomic complex minus the van der Waals radius of the helium atom. Our rationale is that He is the most chemically inert and least polarizable atom, so that its interaction with the outer portions of the electron cloud causes the smallest perturbation of it. We show that such radii, which we denote R(XHe), make good qualitative sense. We also compare our R(XHe) values to more traditional ionic radii from solid crystal X-ray measurements, as well as estimates of such radii from "ionic" gas-phase MF, MOM, MF(+), and MO molecules, where M is a metal atom. Such comparisons lead to interesting conclusions about bonding in ionic crystals and in simple gas-phase oxide and fluoride molecules. The definition is shown to be reasonable for -1, +1, and even for many of the larger +2 atomic ions. Another advantage of the R(XHe) definition is that it is also consistently valid for ground states and excited states of both neutral atoms and atomic ions, even for open-shell np and nd cases where the electron clouds of the ions are not spherically symmetric and R(XHe) thus depends on the "approach" direction of the He atom. Finally, we note that when there is a contribution from covalent bonding with the He atom, and/or in cases where the ion is small and has a very high charge, so that there is distortion even of the He 1s electrons, R(XHe) is not expected to be representative of the size of the ion. We then suggest that in these cases small, and sometimes unphysical, values of R(XHe) are diagnostic of the fact that simple "physical" interactions have been supplemented by a "chemical" component. PMID:20055395

  6. Charge radii of neutron-deficient 36K and 37K

    NASA Astrophysics Data System (ADS)

    Rossi, D. M.; Minamisono, K.; Asberry, H. B.; Bollen, G.; Brown, B. A.; Cooper, K.; Isherwood, B.; Mantica, P. F.; Miller, A.; Morrissey, D. J.; Ringle, R.; Rodriguez, J. A.; Ryder, C. A.; Smith, A.; Strum, R.; Sumithrarachchi, C.

    2015-07-01

    Background: The systematic trend in mean-square charge radii as a function of proton or neutron number exhibits a discontinuity at the nucleon-shell closures. While the established N =28 shell closure is evident in the charge radii of the isotopic chains of K through Mn, a similar signature of the N =20 shell closure is absent in the Ca region. Purpose: The isotope shift between neutron-deficient 36K and 37K was determined to investigate the change of the mean-square charge radii across N =20 in the K isotopic chain. Methods: The D 1 atomic hyperfine spectra of 36K and 37K were measured using an optical pumping and subsequent β -decay asymmetry detection technique. Atomic rate equations were solved to fit the resonant line shape. The result was compared to Skyrme energy-density functional and shell-model calculations. Results: The isotope shift was obtained as δ ν37 ,36=-139 (4 ) (3 ) MHz. Using a re-evaluated isotope shift, δ ν39 ,37=-264 (2 ) (3 ) MHz, the isotope shift relative to 39K was determined to be δ ν39 ,36=-403 (5 ) (4 ) MHz. The differential mean-square charge radius was then deduced as δ 39 ,36=-0.16 (5 ) (8 ) fm2 . The Skyrme energy-density functional and shell-model calculations overpredict the experimental values below N =20 and underpredict them above N =20 , and their agreement is marginal. Conclusions: The absence of the shell-closure signature at N =20 in the K isotopic chain is understood as a balance between the monopole and the quadrupole proton-core polarizations below and above N =20 , respectively.

  7. Freeze-out radii extracted from three-pion cumulants in pp, p-Pb and Pb-Pb collisions at the LHC

    NASA Astrophysics Data System (ADS)

    Abelev, B.; Adam, J.; Adamová, D.; Aggarwal, M. M.; Agnello, M.; Agostinelli, A.; Agrawal, N.; Ahammed, Z.; Ahmad, N.; Ahmed, I.; Ahn, S. U.; Ahn, S. A.; Aimo, I.; Aiola, S.; Ajaz, M.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alici, A.; Alkin, A.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arbor, N.; Arcelli, S.; Armesto, N.; Arnaldi, R.; Aronsson, T.; Arsene, I. C.; Arslandok, M.; Augustinus, A.; Averbeck, R.; Awes, T. C.; Azmi, M. D.; Bach, M.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Baltasar Dos Santos Pedrosa, F.; Baral, R. C.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartke, J.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batyunya, B.; Batzing, P. C.; Baumann, C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bellwied, R.; Belmont-Moreno, E.; Belmont, R.; Belyaev, V.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Berger, M. E.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Bjelogrlic, S.; Blanco, F.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Bogolyubsky, M.; Böhmer, F. V.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Bossú, F.; Botje, M.; Botta, E.; Böttger, S.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Castillo Castellanos, J.; Casula, E. A. R.; Catanescu, V.; Cavicchioli, C.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Chang, B.; Chapeland, S.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Chochula, P.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortese, P.; Cortés Maldonado, I.; Cosentino, M. R.; Costa, F.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dainese, A.; Dang, R.; Danu, A.; Das, D.; Das, I.; Das, K.; Das, S.; Dash, A.; Dash, S.; De, S.; Delagrange, H.; Deloff, A.; Dénes, E.; D'Erasmo, G.; De Caro, A.; de Cataldo, G.; de Cuveland, J.; De Falco, A.; De Gruttola, D.; De Marco, N.; De Pasquale, S.; de Rooij, R.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Di Bari, D.; Di Liberto, S.; Di Mauro, A.; Di Nezza, P.; Djuvsland, Ø.; Dobrin, A.; Dobrowolski, T.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Dørheim, S.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Dutta Majumdar, A. K.; Ehlers, R. J.; Elia, D.; Engel, H.; Erazmus, B.; Erdal, H. A.; Eschweiler, D.; Espagnon, B.; Esposito, M.; Estienne, M.; Esumi, S.; Evans, D.; Evdokimov, S.; Fabris, D.; Faivre, J.; Falchieri, D.; Fantoni, A.; Fasel, M.; Fehlker, D.; Feldkamp, L.; Felea, D.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Floratos, E.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Garishvili, I.; Gerhard, J.; Germain, M.; Gheata, A.; Gheata, M.; Ghidini, B.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Gladysz-Dziadus, E.; Glässel, P.; Gomez Ramirez, A.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Graczykowski, L. K.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Guilbaud, M.; Gulbrandsen, K.; Gulkanyan, H.; Gumbo, M.; Gunji, T.; Gupta, A.; Gupta, R.; Khan, K. H.; Haake, R.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hanratty, L. D.; Hansen, A.; Harris, J. W.; Hartmann, H.; Harton, A.

    2014-12-01

    In high-energy collisions, the spatio-temporal size of the particle production region can be measured using the Bose-Einstein correlations of identical bosons at low relative momentum. The source radii are typically extracted using two-pion correlations, and characterize the system at the last stage of interaction, called kinetic freeze-out. In low-multiplicity collisions, unlike in high-multiplicity collisions, two-pion correlations are substantially altered by background correlations, e.g. mini-jets. Such correlations can be suppressed using three-pion cumulant correlations. We present the first measurements of the size of the system at freeze-out extracted from three-pion cumulant correlations in pp, p-Pb and Pb-Pb collisions at the LHC with ALICE. At similar multiplicity, the invariant radii extracted in p-Pb collisions are found to be 5-15% larger than those in pp, while those in Pb-Pb are 35-55% larger than those in p-Pb. Our measurements disfavor models which incorporate substantially stronger collective expansion in p-Pb as compared to pp collisions at similar multiplicity.

  8. Effects of Bending Radii on the Characteristics of Flexible Organic Solar Cells Investigated by Impedance Analysis.

    PubMed

    Kim, Hoonbae; Ye, Donghyun; Won, Beomhee; Yu, SeGi; Jung, Donggeun

    2016-05-01

    Flexible organic solar cells (OSCs) were fabricated on an indium-tin-oxide (ITO)/poly(ethylene terephthalate) (PET) substrate and were subjected to bending tests with various bending radii. We observed that the photovoltaic properties of the OSCs precipitously deteriorated at a bending radius ≤ 0.75 cm. In order to investigate the effects of the bending test, the changes in the surface morphology and the sheet resistance of the ITO-coated PET samples were investigated, and the photovoltaic properties of bent and unbent OSCs were evaluated. Thereafter, equivalent circuits for the OSCs were assumed and the change in their parameters, such as resistance and capacitance, was observed. PMID:27483935

  9. Systematics of nuclear charge radii of the stable molybdenum isotopes from muonic atoms

    NASA Astrophysics Data System (ADS)

    Schellenberg, L.; Robert-Tissot, B.; Käser, K.; Schaller, L. A.; Schneuwly, H.; Fricke, G.; Glückert, S.; Mallot, G.; Shera, E. B.

    1980-01-01

    The results of precise measurements of the energies of the 2 p{3}/{2}-1 s{1}/{2}and 2 p{1}/{2}-1 s{1}/{2} muonic X-ray transitions of 92Mo, 94Mo, 95Mo, 96Mo, 97Mo, 98Mo and 100Mo are reported. The data were analyzed in terms of the Barrett moments < rke - αr> of the nuclear charge distributions from which the equivalent nuclear radii Rk and the differences ΔRk between neighboring isotopes were computed. Systematic shell effects have been observed at the neutron numbers N = 50 and N = 56.

  10. Possible octupole deformation in Cs and Ba nuclei from their differential radii

    SciTech Connect

    Sheline, R.K.; Jain, A.K.; Jain, K.

    1988-12-01

    The odd-even staggering of the differential radii of Fr and Ra and the Cs and Ba nuclei is compared. This staggering is inverted in the region of known octupole deformation in the Fr and Ra nuclei. The normal staggering is eliminated in the Cs nuclei and attenuated in the Ba nuclei for neutron numbers 85--88. This fact is used to suggest the possible existence of octupole deformation and its neutron number range in the Cs and Ba nuclear ground states.

  11. NEUTRON STARS WITH SMALL RADII-THE ROLE OF {Delta} RESONANCES

    SciTech Connect

    Schuerhoff, Torsten; Schramm, Stefan; Dexheimer, Veronica

    2010-11-20

    Recent neutron star observations suggest that the masses and radii of neutron stars may be smaller than previously considered, which would disfavor a purely nucleonic equation of state (EoS). In our model, we use a flavor SU(3) sigma model that includes {Delta} resonances and hyperons in the EoS. We find that if the coupling of the {Delta} resonances to the vector mesons is slightly smaller than that of the nucleons, we can reproduce both the measured mass-radius relationship and the extrapolated EoS.

  12. Plastic set of smooth large radii of curvature thermal conductance specimens at light loads.

    NASA Technical Reports Server (NTRS)

    Mckinzie, D. J., Jr.

    1972-01-01

    Thermal contact conductance test data at high vacuum were obtained from two Armco iron specimens having smooth, large radii of curvature, convex, one-half wave length surfaces. The data are compared with calculations based on two macroscopic elastic deformation theories and an empirical expression. Major disagreement with the theories and fair agreement with the empirical expression resulted. Plastic deformation of all the contacting surfaces was verified from surface analyzer statistics. These results indicate that the theoretical assumption of macroscopic elastic deformation is inadequate for accurate prediction of heat transfer with light loads for Armco iron specimens similar to those used in this investigation.

  13. Radii and albedos of asteroids 1, 2, 3, 4, 6, 15, 51, 433, and 511

    NASA Technical Reports Server (NTRS)

    Cruikshank, D. P.; Morrison, D.

    1973-01-01

    The following radii (in kilometers) and visual geometric albedos are derived for nine asteroids from 10- and 20-micron radiometry: 1 Ceres (540, .06); 2 Pallas (275, .08); 3 Juno (125, .14); 4 Vesta (270, .21); 6 Hebe (110, .16); 15 Eunomia (135, .15); 51 Nemausa (80, .05); 433 Eros (12, .07); and 511 Davida (180, .04). Vesta has the highest albedo measured for an asteroid, while Davida, the lowest-albedo object in the sample, is one of the darkest known objects in the solar system. The median of all asteroid albedos measured to date is 0.1.-

  14. Plastic set of smooth large radii of curvature thermal conductance specimens at light loads

    NASA Technical Reports Server (NTRS)

    Mckinzie, D. J., Jr.

    1972-01-01

    Thermal contact conductance test data at high vacuum were obtained from two Armco iron specimens having smooth, large radii of curvature, convex, one-half wave length surfaces. The data are compared with calculations based on two macroscopic elastic deformation theories and an empirical expression. Major disagreement with the theories and fair agreement with the empirical expression resulted. Plastic deformation of all the contacting surfaces was verified from surface analyzer statistics. These results indicate that the theoretical assumption of macroscopic elastic deformation is inadequate for accurate prediction of heat transfer with light loads for Armco iron specimens similar to those used in this investigation.

  15. Disk radii and grain sizes in Herschel-resolved debris disks

    SciTech Connect

    Pawellek, Nicole; Krivov, Alexander V.; Marshall, Jonathan P.; Montesinos, Benjamin; Ábrahám, Péter; Moór, Attila; Bryden, Geoffrey; Eiroa, Carlos

    2014-09-01

    The radii of debris disks and the sizes of their dust grains are important tracers of the planetesimal formation mechanisms and physical processes operating in these systems. Here we use a representative sample of 34 debris disks resolved in various Herschel Space Observatory (Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA) programs to constrain the disk radii and the size distribution of their dust. While we modeled disks with both warm and cold components, and identified warm inner disks around about two-thirds of the stars, we focus our analysis only on the cold outer disks, i.e., Kuiper-belt analogs. We derive the disk radii from the resolved images and find a large dispersion for host stars of any spectral class, but no significant trend with the stellar luminosity. This argues against ice lines as a dominant player in setting the debris disk sizes, since the ice line location varies with the luminosity of the central star. Fixing the disk radii to those inferred from the resolved images, we model the spectral energy distribution to determine the dust temperature and the grain size distribution for each target. While the dust temperature systematically increases toward earlier spectral types, the ratio of the dust temperature to the blackbody temperature at the disk radius decreases with the stellar luminosity. This is explained by a clear trend of typical sizes increasing toward more luminous stars. The typical grain sizes are compared to the radiation pressure blowout limit s {sub blow} that is proportional to the stellar luminosity-to-mass ratio and thus also increases toward earlier spectral classes. The grain sizes in the disks of G- to A-stars are inferred to be several times s {sub blow} at all stellar luminosities, in agreement with collisional models of debris disks. The sizes, measured in the units of s {sub blow}, appear to decrease

  16. Radii, shapes, and topography of the satellites of Uranus from limb coordinates

    NASA Astrophysics Data System (ADS)

    Thomas, P. C.

    1988-03-01

    Limb coordinates are used to find the radii, shapes, and local topography of the five large satellites of Uranus. Umbriel, Titania, and Oberon are best fit by spheres. Miranda and Ariel are ellipsoids whose equatorial bulges are consistent with published mean densities. Limb topography on Miranda shows substantial deformation of both old cratered terrain and the younger coronae and complex faulting and uplift at the margins of the coronae. The maximum deformation is about 10 km. Umbriel's limb shows a basin of undetermined origin about 500 km across and 6 km deep.

  17. A white-light /Fe X/H-alpha coronal transient observation to 10 solar radii

    NASA Technical Reports Server (NTRS)

    Wagner, W. J.; Illing, R. M. E.; Sawyer, C. B.; House, L. L.; Sheeley, N. R., Jr.; Howard, R. A.; Koomen, M. J.; Michels, D. J.; Smartt, R. N.; Dryer, M.

    1983-01-01

    Multitelescope observations of the coronal transient of April 15-16, 1980 provide simultaneous data from the Solar Maximum Mission Coronagraph/Polarimeter, the Solwind Coronagraph, and the new Emission line Coronagraph of the Sacramento Peak Observatory. An eruptive prominence-associated white light transient is for the first time seen as an unusual wave or brightening in Fe X 6374 A (but not in Fe XIV 5303 A). Several interpretations of this fleeting enhancement are offered. The prominence shows a slowly increasing acceleration which peaks at the time of the Fe event. The white light loop transient surrounding the prominence expands at a well-documented constant speed to solar radii, with an extrapolated start time at zero height coincident with the surface activity. This loop transient exemplifies those seen above 1.7 solar radii, in that leading the disturbance is a bright N(e)-enhanced) loop rather than a dark one. This is consistent with a report of the behavior of another eruptive event observed by Fisher and Poland (1981) which began as a density depletion in the lower corona, with a bright loop forming at greater altitudes. The top of the bright loop ultimately fades in the outer corona while slow radial growth continues in the legs.

  18. An implicit solvent model for SCC-DFTB with Charge-Dependent Radii

    PubMed Central

    Hou, Guanhua; Zhu, Xiao; Cui, Qiang

    2010-01-01

    Motivated by the need of rapidly exploring the potential energy surface of chemical reactions that involve highly charged species, we have developed an implicit solvent model for the approximate density functional theory, SCC-DFTB. The solvation free energy is calculated using the popular model that employs Poisson-Boltzmann for electrostatics and a surface-area term for non-polar contributions. To balance the treatment of species with different charge distributions, we make the atomic radii that define the dielectric boundary and solute cavity depend on the solute charge distribution. Specifically, the atomic radii are assumed to be linearly dependent on the Mulliken charges and solved self-consistently together with the solute electronic structure. Benchmark calculations indicate that the model leads to solvation free energies of comparable accuracy to the SM6 model (especially for ions), which requires much more expensive DFT calculations. With analytical first derivatives and favorable computational speed, the SCC-DFTB based solvation model can be effectively used, in conjunction with high-level QM calculations, to explore the mechanism of solution reactions. This is illustrated with a brief analysis of the hydrolysis of mono-methyl mono-phosphate ester (MMP) and tri-methyl mono-phosphate ester (TMP). Possible future improvements are also briefly discussed. PMID:20711513

  19. THE INFLUENCE OF ORBITAL ECCENTRICITY ON TIDAL RADII OF STAR CLUSTERS

    SciTech Connect

    Webb, Jeremy J.; Harris, William E.; Sills, Alison; Hurley, Jarrod R.

    2013-02-20

    We have performed N-body simulations of star clusters orbiting in a spherically symmetric smooth galactic potential. The model clusters cover a range of initial half-mass radii and orbital eccentricities in order to test the historical assumption that the tidal radius of a cluster is imposed at perigalacticon. The traditional assumption for globular clusters is that since the internal relaxation time is larger than its orbital period, the cluster is tidally stripped at perigalacticon. Instead, our simulations show that a cluster with an eccentric orbit does not need to fully relax in order to expand. After a perigalactic pass, a cluster recaptures previously unbound stars, and the tidal shock at perigalacticon has the effect of energizing inner region stars to larger orbits. Therefore, instead of the limiting radius being imposed at perigalacticon, it more nearly traces the instantaneous tidal radius of the cluster at any point in the orbit. We present a numerical correction factor to theoretical tidal radii calculated at perigalacticon which takes into consideration both the orbital eccentricity and current orbital phase of the cluster.

  20. Radii and Shape of Pluto and Charon: Preliminary Results from New Horizons

    NASA Astrophysics Data System (ADS)

    Nimmo, F.; Lisse, C. M.; Umurhan, O. M.; McKinnon, W. B.; Buie, M. W.; Lauer, T.; Beyer, R. A.; Moore, J. M.; Stern, A.; Weaver, H. A., Jr.; Olkin, C.; Ennico Smith, K.; Young, L. A.; Bierson, C. J.

    2015-12-01

    Accurate determinations of the mean radii of Pluto and Charon are important for establishing their densities and thus bulk composition. A fossil bulge, if present, would place constraints on the thermal and orbital evolution of these bodies [1,2]. The New Horizons LORRI imaging system [3] has provided global images of Pluto and Charon, with best resolutions of 3.8 and 2.3 km/pix, respectively. Three separate approaches have been used to determine mean radii and shape from the images, two using a threshold DN value [4,5] and one using a maximum gradient method. These approaches were validated using synthetic images having a range of photometric functions. Tradeoffs between the limb center location and the derived shape in individual images can be reduced by combining limb picks from different images. Preliminary results for both Pluto and Charon will be presented. [1] Robuchon & Nimmo, Icarus 216, 426, 2011. [2] McKinnon & Singer, DPS 46, abs. no. 419.07, 2014. [3] Cheng et al., SSR 140, 189, 2008. [4] Dermott & Thomas, Icarus 73, 25, 1988. [5] Thomason & Nimmo, LPSC 46, abs. no. 1462, 2015.

  1. Nonlinear particle behavior during cross-type optical particle separation

    SciTech Connect

    Kim, Sang Bok; Lee, Kyung Heon; Sung, Hyung Jin; Kim, Sang Soo

    2009-12-28

    The effects of varying the ratio of the optical force to the viscous drag force, termed S, on cross-type optical particle separation were investigated experimentally to test previous theoretical predictions. The experiments were performed for various flow velocities, powers of the laser beam, and radii of the laser beam waist and the particles. The behaviors of the particles during optical separation were examined by measuring the retention distances and analyzing the particle trajectories. For small values of S, the particles move with constant velocity in the flow direction and the retention distance increases linearly with S. However, the particles accelerate and decelerate within the laser beam and the retention distance increases nonlinearly with S when S increases further.

  2. Moving particle composition analyzer

    NASA Technical Reports Server (NTRS)

    Auer, S. O. (Inventor)

    1976-01-01

    A mass spectrometry apparatus for analyzing the composition of moving microscopic particles is introduced. The apparatus includes a capacitor with a front electrode upon which the particles impinge, a back electrode, and a solid dielectric sandwiched between the front and back electrodes. In one embodiment, the electrodes and dielectric are arcuately shaped as concentric peripheral segments of different spheres having a common center and different radii. The front electrode and dielectric together have a thickness such that an impinging particle can penetrate them. In a second embodiment, the capacitor has planar, parallel electrodes, in which case the ejected positive ions are deflected downstream of a planar grid by a pair of spaced, arcuate capacitor plates having a region between them through which the ejected ions travel.

  3. High Precision, Directly Determined Radii and Effective Temperatures for Giant Stars

    NASA Astrophysics Data System (ADS)

    van Belle, Gerard

    Mission Statement. The radius and temperature scale of giant stars across the Hertzsprung-Russell diagram from red giant branch stars to horizontal branch stars is understood well enough to enable an accurate prediction of temperature and size for a given star to no better than ~2.5% and ~20%, respectively, based upon photometry. The primary reason for this is the lack of empirically determined radii and temperatures across the giant branches. One of the long-running strengths of optical interferometry has been the empirical determination of fundamental stellar parameters. Through direct measurements of effective temperature and linear radius, methods such as photometric colors that indirectly predict such values can be calibrated. A substantial body of data on this topic collected for giant stars remains unpublished and stands to benefit from the advances in ancillary data sources and computational techniques of the last dozen years. Previous efforts in this regard have been limited by data sample breadth and depth. The Experiment. We will use multi-technique and multi-wavelength data available in NASA's Archives to directly measure angular sizes and bolometric fluxes for giant stars, establishing the radius-temperature scale across the giant branches. Interferometric data from NASA's Palomar Testbed Interferometer (PTI) Archive in conjunction with recent advances in calibration techniques will allow us to directly establish fundamental parameters of temperature and radius for 425 giant stars at unprecedented levels of accuracy. The majority of these objects was observed repeatedly over the 11-year run of this well- understood instrument, allowing for exquisite control of observational systematics. Optical, near-infrared and mid-infrared data from NASA Archives, including 2MASS, COBE, MSX, and WISE will constrain the bolometric fluxes; the recent reanalysis of the Hipparcos data will provide unparalleled distances to each of the 425 giant stars in the sample. We

  4. A finite element stress analysis of spur gears including fillet radii and rim thickness effects

    NASA Technical Reports Server (NTRS)

    Chang, S. H.; Huston, R. L.; Coy, J. J.

    1982-01-01

    Spur gear stress analysis results are presented for a variety of loading conditions, support conditions, fillet radii, and rim thickness. These results are obtained using the SAP IV finite-element code. The maximum stresses, occurring at the root surface, substantially increase with decreasing rim thickness for partially supported rims (that is, with loose-fitting hubs). For fully supported rims (that is, with tight-fitting hubs), the root surface stresses slightly decrease with decreasing rim thickness. The fillet radius is found to have a significant effect upon the maximum stresses at the root surface. These stresses increase with increasing fillet radius. The fillet radius has little effect upon the internal root section stresses.

  5. Measurement of apparent cell radii using a multiple wave vector diffusion experiment.

    PubMed

    Weber, T; Ziener, C H; Kampf, T; Herold, V; Bauer, W R; Jakob, P M

    2009-04-01

    It had been previously shown that an idealized version of the two-wave-vector extension of the NMR pulsed-field-gradient spin echo diffusion experiment can be used to determine the apparent radius of geometries with restricted diffusion. In the present work, the feasibility of the experiment was demonstrated in an NMR imaging experiment, in which the apparent radius of axons in white matter tissue was determined. Moreover, numerical simulations have been carried out to determine the reliability of the results. For small diffusion times, the radius is systematically underestimated. Larger gradient area, finite length gradient pulses, and a statistical distribution of radii within a voxel all have a minor influence on the estimated radius. PMID:19205023

  6. Changes in the mean square charge radii and electromagnetic moments of neutron-deficient Bi isotopes

    NASA Astrophysics Data System (ADS)

    Barzakh, A. E.; Batist, L. Kh.; Fedorov, D. V.; Ivanov, V. S.; Molkanov, P. L.; Moroz, F. V.; Orlov, S. Yu.; Panteleev, V. N.; Seliverstov, M. D.; Volkov, Yu. M.

    2015-10-01

    In-source laser spectroscopy experiments for neutron deficient bismuth isotopes at the 306.77 nm atomic transition were carried out at the IRIS (Investigation of Radioactive Isotopes on Synchrocyclotron) facility of Petersburg Nuclear Physics Institute (PNPI). New data on isotope shifts and hyperfine structure for 189-198, 211Bi isotopes and isomers were obtained. The changes in the mean-square charge radii and the magnetic moment values were deduced. Marked deviation from the nearly spherical behavior for ground states of bismuth isotopes at N < 109 is demonstrated, in contrast to the lead and thallium isotopic chains. The big isomer shift between I = 1/2 (intruder) and I = 9/2 (normal) states for odd Bi isotopes (A = 193, 195, 197) was found.

  7. Changes in the mean square charge radii and electromagnetic moments of neutron-deficient Bi isotopes

    SciTech Connect

    Barzakh, A. E. Batist, L. Kh.; Fedorov, D. V.; Ivanov, V. S.; Molkanov, P. L.; Moroz, F. V.; Orlov, S. Yu.; Panteleev, V. N.; Seliverstov, M. D.; Volkov, Yu. M.

    2015-10-15

    In-source laser spectroscopy experiments for neutron deficient bismuth isotopes at the 306.77 nm atomic transition were carried out at the IRIS (Investigation of Radioactive Isotopes on Synchrocyclotron) facility of Petersburg Nuclear Physics Institute (PNPI). New data on isotope shifts and hyperfine structure for {sup 189–198,} {sup 211}Bi isotopes and isomers were obtained. The changes in the mean-square charge radii and the magnetic moment values were deduced. Marked deviation from the nearly spherical behavior for ground states of bismuth isotopes at N < 109 is demonstrated, in contrast to the lead and thallium isotopic chains. The big isomer shift between I = 1/2 (intruder) and I = 9/2 (normal) states for odd Bi isotopes (A = 193, 195, 197) was found.

  8. Neutron star masses and radii from quiescent low-mass x-ray binaries

    SciTech Connect

    Lattimer, James M.; Steiner, Andrew W. E-mail: steiner3@uw.edu

    2014-04-01

    We perform a systematic analysis of neutron star radius constraints from five quiescent low-mass X-ray binaries and examine how they depend on measurements of their distances and amounts of intervening absorbing material, as well as their assumed atmospheric compositions. We construct and calibrate to published results a semi-analytic model of the neutron star atmosphere which approximates these effects for the predicted masses and radii. Starting from mass and radius probability distributions established from hydrogen-atmosphere spectral fits of quiescent sources, we apply this model to compute alternate sets of probability distributions. We perform Bayesian analyses to estimate neutron star mass-radius curves and equation of state (EOS) parameters that best-fit each set of distributions, assuming the existence of a known low-density neutron star crustal EOS, a simple model for the high-density EOS, causality, and the observation that the neutron star maximum mass exceeds 2 M {sub ☉}. We compute the posterior probabilities for each set of distance measurements and assumptions about absorption and composition. We find that, within the context of our assumptions and our parameterized EOS models, some absorption models are disfavored. We find that neutron stars composed of hadrons are favored relative to those with exotic matter with strong phase transitions. In addition, models in which all five stars have hydrogen atmospheres are found to be weakly disfavored. Our most likely models predict neutron star radii that are consistent with current experimental results concerning the nature of the nucleon-nucleon interaction near the nuclear saturation density.

  9. Measurements of Faraday Rotation through the Solar Corona at 4.6 Solar Radii

    NASA Astrophysics Data System (ADS)

    Kooi, Jason E.; Fischer, P. D.; Buffo, J. J.; Spangler, S. R.

    2013-07-01

    Identifying and understanding (1) the coronal heating mechanism and (2) the acceleration mechanism for the high-speed solar wind are two of the most important modern problems in solar physics. Many competing models of the high-speed solar wind depend on the solar magnetic field inside heliocentric distances of 5 solar radii. We report on sensitive VLA full-polarization observations made in August, 2011, at 5.0 and 6.1 GHz (each with a bandwidth of 128 MHz) of the radio galaxy 3C228 through the solar corona at heliocentric distances of 4.6 - 5.0 solar radii. Observations at 5.0 GHz (C-band frequencies) permit measurements deeper in the corona than previous VLA observations at 1.4 and 1.7 GHz. These Faraday rotation observations provide unique information on the plasma density and magnetic field strength in this region of the corona. The measured Faraday rotation on this day was lower than our a priori expectations, but we have successfully modeled the measurement in terms of observed properties of the corona on the day of observation. Further, 3C228 provides two lines of sight (separated by 46”) that allow measurement of differential Faraday rotation. These data may provide constraints on the magnitude of coronal currents and, thus, on the role Joule heating plays in the corona. Fluctuations in the observed rotation measure may also place constraints on wave-turbulence models by constraining the magnitude of coronal Alfvén waves.

  10. Neutron star radii, universal relations, and the role of prior distributions

    DOE PAGESBeta

    Steiner, Andrew W.; Lattimer, James M.; Brown, Edward F.

    2016-02-02

    We investigate constraints on neutron star structure arising from the assumptions that neutron stars have crusts, that recent calculations of pure neutron matter limit the equation of state of neutron star matter near the nuclear saturation density, that the high-density equation of state is limited by causality and the largest high-accuracy neutron star mass measurement, and that general relativity is the correct theory of gravity. We explore the role of prior assumptions by considering two classes of equation of state models. In a first, the intermediate- and high-density behavior of the equation of state is parameterized by piecewise polytropes. Inmore » the second class, the high-density behavior of the equation of state is parameterized by piecewise continuous line segments. The smallest density at which high-density matter appears is varied in order to allow for strong phase transitions above the nuclear saturation density. We critically examine correlations among the pressure of matter, radii, maximum masses, the binding energy, the moment of inertia, and the tidal deformability, paying special attention to the sensitivity of these correlations to prior assumptions about the equation of state. It is possible to constrain the radii of 1.4 solar mass neutron stars to be larger than 10 km, even without consideration of additional astrophysical observations, for example, those from photospheric radius expansion bursts or quiescent low-mass X-ray binaries. We are able to improve the accuracy of known correlations between the moment of inertia and compactness as well as the binding energy and compactness. Furthermore, we also demonstrate the existence of a correlation between the neutron star binding energy and the moment of inertia.« less

  11. THE MASS-RADIUS RELATION FOR 65 EXOPLANETS SMALLER THAN 4 EARTH RADII

    SciTech Connect

    Weiss, Lauren M.; Marcy, Geoffrey W.

    2014-03-01

    We study the masses and radii of 65 exoplanets smaller than 4 R {sub ⊕} with orbital periods shorter than 100 days. We calculate the weighted mean densities of planets in bins of 0.5 R {sub ⊕} and identify a density maximum of 7.6  g cm{sup –3} at 1.4 R {sub ⊕}. On average, planets with radii up to R {sub P} = 1.5 R {sub ⊕} increase in density with increasing radius. Above 1.5 R {sub ⊕}, the average planet density rapidly decreases with increasing radius, indicating that these planets have a large fraction of volatiles by volume overlying a rocky core. Including the solar system terrestrial planets with the exoplanets below 1.5 R {sub ⊕}, we find ρ{sub P} = 2.43 + 3.39(R {sub P}/R {sub ⊕}) g cm{sup –3} for R {sub P} < 1.5 R {sub ⊕}, which is consistent with rocky compositions. For 1.5 ≤ R {sub P}/R {sub ⊕} < 4, we find M {sub P}/M {sub ⊕} = 2.69(R {sub P}/R {sub ⊕}){sup 0.93}. The rms of planet masses to the fit between 1.5 and 4 R {sub ⊕} is 4.3 M {sub ⊕} with reduced χ{sup 2} = 6.2. The large scatter indicates a diversity in planet composition at a given radius. The compositional diversity can be due to planets of a given volume (as determined by their large H/He envelopes) containing rocky cores of different masses or compositions.

  12. Fossil hominin radii from the Sima de los Huesos Middle Pleistocene site (Sierra de Atapuerca, Spain).

    PubMed

    Rodríguez, Laura; Carretero, José Miguel; García-González, Rebeca; Lorenzo, Carlos; Gómez-Olivencia, Asier; Quam, Rolf; Martínez, Ignacio; Gracia-Téllez, Ana; Arsuaga, Juan Luis

    2016-01-01

    Complete radii in the fossil record preceding recent humans and Neandertals are very scarce. Here we introduce the radial remains recovered from the Sima de los Huesos (SH) site in the Sierra de Atapuerca between 1976 and 2011 and which have been dated in excess of 430 ky (thousands of years) ago. The sample comprises 89 specimens, 49 of which are attributed to adults representing a minimum of seven individuals. All elements are described anatomically and metrically, and compared with other fossil hominins and recent humans in order to examine the phylogenetic polarity of certain radial features. Radial remains from SH have some traits that differentiate them from those of recent humans and make them more similar to Neandertals, including strongly curved shafts, anteroposterior expanded radial heads and both absolutely and relatively long necks. In contrast, the SH sample differs from Neandertals in showing a high overall gracility as well as a high frequency (80%) of an anteriorly oriented radial tuberosity. Thus, like the cranial and dental remains from the SH site, characteristic Neandertal radial morphology is not present fully in the SH radii. We also analyzed the cross-sectional properties of the SH radial sample at two different levels: mid-shaft and at the midpoint of the neck length. When standardized by shaft length, no difference in the mid-shaft cross-sectional properties were found between the SH hominins, Neandertals and recent humans. Nevertheless, due to their long neck length, the SH hominins show a higher lever efficiency than either Neandertals or recent humans. Functionally, the SH radial morphology is consistent with more efficient pronation-supination and flexion-extension movements. The particular trait composition in the SH sample and Neandertals resembles more closely morphology evident in recent human males. PMID:26767960

  13. Neutron star radii, universal relations, and the role of prior distributions

    NASA Astrophysics Data System (ADS)

    Steiner, A. W.; Lattimer, J. M.; Brown, E. F.

    2016-02-01

    We investigate constraints on neutron star structure arising from the assumptions that neutron stars have crusts, that recent calculations of pure neutron matter limit the equation of state of neutron star matter near the nuclear saturation density, that the high-density equation of state is limited by causality and the largest high-accuracy neutron star mass measurement, and that general relativity is the correct theory of gravity. We explore the role of prior assumptions by considering two classes of equation of state models. In a first, the intermediate- and high-density behavior of the equation of state is parameterized by piecewise polytropes. In the second class, the high-density behavior of the equation of state is parameterized by piecewise continuous line segments. The smallest density at which high-density matter appears is varied in order to allow for strong phase transitions above the nuclear saturation density. We critically examine correlations among the pressure of matter, radii, maximum masses, the binding energy, the moment of inertia, and the tidal deformability, paying special attention to the sensitivity of these correlations to prior assumptions about the equation of state. It is possible to constrain the radii of 1.4 M_{⊙} neutron stars to be larger than 10km, even without consideration of additional astrophysical observations, for example, those from photospheric radius expansion bursts or quiescent low-mass X-ray binaries. We are able to improve the accuracy of known correlations between the moment of inertia and compactness as well as the binding energy and compactness. We also demonstrate the existence of a correlation between the neutron star binding energy and the moment of inertia.

  14. Hydrodynamical Numerical Simulation of Wind Production from Black Hole Hot Accretion Flows at Very Large Radii

    NASA Astrophysics Data System (ADS)

    Bu, De-Fu; Yuan, Feng; Gan, Zhao-Ming; Yang, Xiao-Hong

    2016-02-01

    Previous works show that strong winds exist in hot accretion flows around black holes. Those works focus only on the region close to the black hole, so it is unknown whether or where the wind production stops at large radii. In this paper, we investigate this problem with hydrodynamical simulations. We take into account the gravities of both the black hole and the nuclear star clusters. For the latter, we assume that the velocity dispersion of stars is a constant and its gravitational potential \\propto {σ }2{ln}(r), where σ is the velocity dispersion of stars, and r is the distance from the center of the galaxy. We focus on the region where the gravitational potential is dominated by the star cluster. We find that, just as for the accretion flow at small radii, the mass inflow rate decreases inward, and the flow is convectively unstable. However, a trajectory analysis shows that there is very little wind launched from the flow. Our result, combined with the results of Yuan et al.’s study from 2015, indicates that the mass flux of wind launched from hot accretion flow {\\dot{M}}{{wind}}={\\dot{M}}{{BH}}(r/20{r}s), with r≲ {R}A\\equiv {{GM}}{{BH}}/{σ }2. Here, {\\dot{M}}{{BH}} is the accretion rate at the black hole horizon, and RA is similar to the Bondi radius. We argue that the inward decrease of inflow rate is not due to mass loss via wind, but to convective motion. The disappearance of wind outside RA must be due to the change of the gravitational potential, but the exact reason remains to be probed.

  15. Nuclear charge and neutron radii and nuclear matter: Trend analysis in Skyrme density-functional-theory approach

    NASA Astrophysics Data System (ADS)

    Reinhard, P.-G.; Nazarewicz, W.

    2016-05-01

    Background: Radii of charge and neutron distributions are fundamental nuclear properties. They depend on both nuclear interaction parameters related to the equation of state of infinite nuclear matter and on quantal shell effects, which are strongly impacted by the presence of nuclear surface. Purpose: In this work, by studying the correlation of charge and neutron radii, and neutron skin, with nuclear matter parameters, we assess different mechanisms that drive nuclear sizes. Method: We apply nuclear density functional theory using a family of Skyrme functionals obtained by means of optimization protocols, which do not include any radius information. By performing the Monte Carlo sampling of reasonable functionals around the optimal parametrization, we scan all correlations between nuclear matter properties and observables characterizing charge and neutron distributions of spherical closed-shell nuclei 48Ca,208Pb, and 298Fl. Results: By considering the influence of various nuclear matter properties on charge and neutron radii in a multidimensional parameter space of Skyrme functionals, we demonstrate the existence of two strong relationships: (i) between the nuclear charge radii and the saturation density of symmetric nuclear matter ρ0, and (ii) between the neutron skins and the slope of the symmetry energy L . The impact of other nuclear matter properties on nuclear radii is weak or nonexistent. For functionals optimized to experimental binding energies only, proton and neutron radii are found to be weakly correlated due to canceling trends from different nuclear matter characteristics. Conclusion: The existence of only two strong relations connecting nuclear radii with nuclear matter properties has important consequences. First, by requiring that the nuclear functional reproduces the empirical saturation point of symmetric nuclear matter practically fixes the charge (or proton) radii, and vice versa. This explains the recent results of ab initio calculations

  16. Effect of ionic radii on the Curie temperature in Ba1-x-ySrxCayTiO3 compounds

    PubMed Central

    Berenov, A.; Le Goupil, F.; Alford, N.

    2016-01-01

    A series of Ba1-x-ySrxCayTiO3 compounds were prepared with varying average ionic radii and cation disorder on A-site. All samples showed typical ferroelectric behavior. A simple empirical equation correlated Curie temperature, TC, with the values of ionic radii of A-site cations. This correlation was related to the distortion of TiO6 octahedra observed during neutron diffraction studies. The equation was used for the selection of compounds with predetermined values of TC. The effects of A-site ionic radii on the temperatures of phase transitions in Ba1-x-ySrxCayTiO3 were discussed. PMID:27324841

  17. Particle Correlations with the PHENIX Experiment

    SciTech Connect

    Johnson, S C

    2002-01-20

    Results of identical pion correlations from the first year of data collection with the PHENIX detector at RHIC ({radical}S{sub NN} = 130 GeV) are presented. PHENIX has good particle identification using an electromagnetic calorimeter for timing, leading to identified pions from .2 to 1 GeV/c. This extends the range of previously measured correlation radii at this energy to (k{sub T}) = 633MeV/c. The beam energy dependence of the HBT radii are studied in depth and no significant dependence of the transverse radii is present. The longitudinal correlation length has a moderate energy dependence. Furthermore, theoretical predictions of R{sub out}/R{sub side} severely underpredict the measured ratio, which is consistent with unity for all k{sub T}. The implications of these results are considered.

  18. LIGHT PRESSURE: Theoretical study of the light pressure force acting on a spherical dielectric particle of an arbitrary size in the interference field of two plane monochromatic electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Guzatov, D. V.; Gaida, L. S.; Afanas'ev, Anatolii A.

    2008-12-01

    The light pressure force acting on a spherical dielectric particle in the interference field of two plane monochromatic electromagnetic waves is studied in detail for different particle radii and angles of incidence of waves.

  19. Radii, masses, and ages of 18 bright stars using interferometry and new estimations of exoplanetary parameters

    NASA Astrophysics Data System (ADS)

    Ligi, R.; Creevey, O.; Mourard, D.; Crida, A.; Lagrange, A.-M.; Nardetto, N.; Perraut, K.; Schultheis, M.; Tallon-Bosc, I.; ten Brummelaar, T.

    2016-02-01

    Context. Accurate stellar parameters are needed in numerous domains of astrophysics. The position of stars on the Hertzsprung-Russell diagram is an important indication of their structure and evolution, and it helps improve stellar models. Furthermore, the age and mass of stars hosting planets are required elements for studying exoplanetary systems. Aims: We aim at determining accurate parameters of a set of 18 bright exoplanet host and potential host stars from interferometric measurements, photometry, and stellar models. Methods: Using the VEGA/CHARA interferometer operating in the visible domain, we measured the angular diameters of 18 stars, ten of which host exoplanets. We combined them with their distances to estimate their radii. We used photometry to derive their bolometric flux and, then, their effective temperature and luminosity to place them on the H-R diagram. We then used the PARSEC models to derive their best fit ages and masses, with error bars derived from Monte Carlo calculations. Results: Our interferometric measurements lead to an average of 1.9% uncertainty on angular diameters and 3% on stellar radii. There is good agreement between measured and indirect estimations of angular diameters (either from SED fitting or from surface brightness relations) for main sequence (MS) stars, but not as good for more evolved stars. For each star, we provide a likelihood map in the mass-age plane; typically, two distinct sets of solutions appear (an old and a young age). The errors on the ages and masses that we provide account for the metallicity uncertainties, which are often neglected by other works. From measurements of its radius and density, we also provide the mass of 55 Cnc independently of models. From the stellar masses, we provide new estimates of semi-major axes and minimum masses of exoplanets with reliable uncertainties. We also derive the radius, density, and mass of 55 Cnc e, a super-Earth that transits its stellar host. Our exoplanetary

  20. Adaptive niche radii and niche shapes approaches for niching with the CMA-ES.

    PubMed

    Shir, Ofer M; Emmerich, Michael; Bäck, Thomas

    2010-01-01

    While the motivation and usefulness of niching methods is beyond doubt, the relaxation of assumptions and limitations concerning the hypothetical search landscape is much needed if niching is to be valid in a broader range of applications. Upon the introduction of radii-based niching methods with derandomized evolution strategies (ES), the purpose of this study is to address the so-called niche radius problem. A new concept of an adaptive individual niche radius is applied to niching with the covariance matrix adaptation evolution strategy (CMA-ES). Two approaches are considered. The first approach couples the radius to the step size mechanism, while the second approach employs the Mahalanobis distance metric with the covariance matrix mechanism for the distance calculation, for obtaining niches with more complex geometrical shapes. The proposed approaches are described in detail, and then tested on high-dimensional artificial landscapes at several levels of difficulty. They are shown to be robust and to achieve satisfying results. PMID:20064027

  1. Quantifying mass segregation and new core radii for 54 Milky Way globular clusters

    SciTech Connect

    Goldsbury, Ryan; Heyl, Jeremy; Richer, Harvey E-mail: heyl@phas.ubc.ca

    2013-11-20

    We present core radii for 54 Milky Way globular clusters determined by fitting King-Michie models to cumulative projected star count distributions. We find that fitting star counts rather than surface brightness profiles produces results that differ significantly due to the presence of mass segregation. The sample in each cluster is further broken down into various mass groups, each of which is fit independently, allowing us to determine how the concentration of each cluster varies with mass. The majority of the clusters in our sample show general agreement with the standard picture that more massive stars will be more centrally concentrated. We find that core radius versus stellar mass can be fit with a two-parameter power law. The slope of this power law is a value that describes the amount of mass segregation present in the cluster, and is measured independently of our distance from the cluster. This value correlates strongly with the core relaxation time and physical size of each cluster. Supplementary figures are also included showing the best fits and likelihood contours of fit parameters for all 54 clusters.

  2. Alfvenic Turbulence from the Sun to 65 Solar Radii: Numerical predictions.

    NASA Astrophysics Data System (ADS)

    Perez, J. C.; Chandran, B. D. G.

    2015-12-01

    The upcoming NASA Solar Probe Plus (SPP) mission will fly to within 9 solar radii from the solar surface, about 7 times closer to the Sun than any previous spacecraft has ever reached. This historic mission will gather unprecedented remote-sensing data and the first in-situ measurements of the plasma in the solar atmosphere, which will revolutionize our knowledge and understanding of turbulence and other processes that heat the solar corona and accelerate the solar wind. This close to the Sun the background solar-wind properties are highly inhomogeneous. As a result, outward-propagating Alfven waves (AWs) arising from the random motions of the photospheric magnetic-field footpoints undergo strong non-WKB reflections and trigger a vigorous turbulent cascade. In this talk I will discuss recent progress in the understanding of reflection-driven Alfven turbulence in this scenario by means of high-resolution numerical simulations, with the goal of predicting the detailed nature of the velocity and magnetic field fluctuations that the SPP mission will measure. In particular, I will place special emphasis on relating the simulations to relevant physical mechanisms that might govern the radial evolution of the turbulence spectra of outward/inward-propagating fluctuations and discuss the conditions that lead to universal power-laws.

  3. Tracing the stellar halo of an early type galaxy out to 25 effective radii

    NASA Astrophysics Data System (ADS)

    Rejkuba, Marina

    2016-08-01

    We have used ACS and WFC3 cameras on board HST to resolve stars in the halo of NGC 5128 out to 140 kpc (25 effective radii, R eff) along the major axis and 70 kpc (13 R eff) along the minor axis. This dataset provides an unprecedented radial coverage of stellar halo properties in any galaxy. Color-magnitude diagrams clearly reveal the presence of the red giant branch stars belonging to the halo of NGC 5128 even in the most distant fields. The V-I colors of the red giants enable us to measure the metallicity distribution in each field and so map the metallicity gradient over the sampled area. The stellar metallicity follows a shallow gradient and even out at 140 kpc (25 R eff) its median value does not go below [M/H]~-1 dex. We observe significant field-to-field metallicity and stellar density variations. The star counts are higher along the major axis when compared to minor axis field located 90 kpc from the galaxy centre, indicating flattening in the outer halo. These observational results provide new important constraints for the assembly history of the halo and the formation of this gE galaxy.

  4. Star Formation in Dwarf Galaxies as a Function of Cluster-Centric Radii

    NASA Astrophysics Data System (ADS)

    Rude, Cody; Barkhouse, Wayne

    2015-01-01

    Galaxy clusters form the largest structures in the universe. The cluster galaxy population differs both by morphology and star formation histories relative to the field population. Several physical mechanisms have been proposed to account for these differences, including ram pressure stripping due to the intracluster medium, and harassment from close encounters with other galaxies. Dwarf galaxies could prove to be particularly important as their low mass makes them more susceptible to external influences. This study looks for evidence of enhanced/quenching of star formation in dwarf galaxies using photometric u- and r-band data of several Abell clusters taken with the CFHT. From the combined sample, scaled by r200, composite luminosity functions (LFs) and histograms of galaxy color at various cluster-centric radii are constructed. An increase in the faint-end slope of the u-band LF relative to the r-band is a possible indicator of enhanced star formation. Comparisons of the inner and outer regions of the cluster sample may yield insights into the physical mechanisms that affect star formation of infalling cluster dwarf galaxies.

  5. GCM estimate of the indirect aerosol forcing using satellite-retrieved cloud droplet effective radii

    SciTech Connect

    Boucher, O.

    1995-05-01

    In a recent paper, satellite data radiances were analyzed to retrieve cloud droplet effective radii and significant interhemispheric differences for both maritime and continental clouds were reported. The mean cloud droplet radius in the Northern Hemisphere is smaller than in the Southern Hemisphere by about 0.7 {mu}m. This hemispheric contrast suggests the presence of an aerosol effect on cloud droplet size and is consistent with higher cloud condensation nuclei number concentration in the Northern Hemisphere due to anthropogenic production of aerosol precursors. In the present study, we constrain a climate model with the satellite retrievals and discuss the climate forcing that can be inferred from the observed distribution of cloud droplet radius. Based on two sets of experiments, this sensitivity study suggests that the indirect radiative forcing by anthropogenic aerosols could be about -0.6 or -1 W m{sup -2} averaged in the 0{degrees}-50{degrees}N latitude band. The uncertainty of these estimates is difficult to assess but is at least 50%. 30 refs., 3 figs., 1 tab.

  6. Fabrication of large radii toroidal surfaces by single point diamond turning

    SciTech Connect

    Cunningham, J.P.; Marlar, T.A.; Miller, A.C.

    1995-12-31

    An unconventional machining technique has been developed for producing relatively large radii quasi-toroidal surfaces which could not normally be produced by conventional diamond turning technology. The maximum radial swing capacity of a diamond turning lathe is the limiting factor for the rotational radius of any toroid. A typical diamond turned toroidal surface is produced when a part is rotated about the spindle axis while the diamond tool contours the surface with any curved path. Toric surfaces sliced horizontally, have been used in laser resonator cavities. This paper will address the fabrication of a special case of toroids where a rotating tool path is a circle whose center is offset from the rotational axis of the toroid by a distance greater than the minor radius of the tool path. The quasi-toroidal surfaces produced by this technique approximate all asymmetrical combinations of concave/convex sections of a torus. Other machine configurations have been reported which offer alternative approaches to the fabrication of concave asymmetric aspheric surfaces.

  7. Few-Nucleon Charge Radii and a Precision Isotope Shift Measurement in Helium

    NASA Astrophysics Data System (ADS)

    Hassan Rezaeian, Nima; Shiner, David

    2015-10-01

    Recent improvements in atomic theory and experiment provide a valuable method to precisely determine few nucleon charge radii, complementing the more direct scattering approaches, and providing sensitive tests of few-body nuclear theory. Some puzzles with respect to this method exist, particularly in the muonic and electronic measurements of the proton radius, known as the proton puzzle. Perhaps this puzzle will also exist in nuclear size measurements in helium. Muonic helium measurements are ongoing while our new electronic results will be discussed here. We measured precisely the isotope shift of the 23S - 23P transitions in 3He and 4He. The result is almost an order of magnitude more accurate than previous measured values. To achieve this accuracy, we implemented various experimental techniques. We used a tunable laser frequency discriminator and electro-optic modulation technique to precisely control the frequency and intensity. We select and stabilize the intensity of the required sideband and eliminate unused sidebands. The technique uses a MEMS fiber switch (ts = 10 ms) and several temperature stabilized narrow band (3 GHz) fiber gratings. A beam with both species of helium is achieved using a custom fiber laser for simultaneous optical pumping. A servo-controlled retro-reflected laser beam eliminates Doppler effects. Careful detection design and software are essential for unbiased data collection. Our new results will be compared to previous measurements.

  8. Few-Nucleon Charge Radii and a Precision Isotope Shift Measurement in Helium

    NASA Astrophysics Data System (ADS)

    Hassan Rezaeian, Nima; Shiner, David

    2015-05-01

    Precision atomic theory and experiment provide a valuable method to determine few nucleon charge radii, complementing the more direct scattering approaches, and providing sensitive tests of few-body nuclear theory. Some puzzles with respect to this method exist, particularly in the muonic and electronic measurements of the proton radius, and as well with respect to measurements of nuclear size in helium. We perform precision measurements of the isotope shift of the 23S -23P transitions in 3He and 4He. A tunable laser frequency discriminator and electro-optic modulation technique give precise frequency and intensity control. We select (ts <50 ms) and stabilize the intensity of the required sideband and eliminate the unused sidebands (<= 10¬5) . The technique uses a MEMS fiber switch (ts = 10 ms) and several temperature stabilized narrow band (3 GHz) fiber gratings. A fiber based optical circulator and amplifier provide the desired isolation and net gain for the selected frequency. A beam with both species of helium is achieved using a custom fiber laser for simultaneous optical pumping. A servo-controlled retro-reflected laser beam eliminates Doppler effects. Careful detection design and software control allows for unbiased data collection. Current results will be discussed. This work is supported by NSF PHY-1068868 and PHY-1404498.

  9. A Chronology of Annual-Mean Effective Radii of Stratospheric Aerosols from Volcanic Eruptions During the Twentieth Century as Derived From Ground-based Spectral Extinction Measurements

    NASA Technical Reports Server (NTRS)

    Strothers, Richard B.; Hansen, James E. (Technical Monitor)

    2001-01-01

    Stratospheric extinction can be derived from ground-based spectral photometric observations of the Sun and other stars (as well as from satellite and aircraft measurements, available since 1979), and is found to increase after large volcanic eruptions. This increased extinction shows a characteristic wavelength dependence that gives information about the chemical composition and the effective (or area weighted mean) radius of the particles responsible for it. Known to be tiny aerosols constituted of sulfuric acid in a water solution, the stratospheric particles at midlatitudes exhibit a remarkable uniformity of their column-averaged effective radii r(sub eff) in the first few months after the eruption. Considering the seven largest eruptions of the twentieth century, r(sub eff) at this phase of peak aerosol abundance is approx. 0.3 micrometers in all cases. A year later, r(sub eff) either has remained about the same size (almost certainly in the case of the Katmai eruption of 1912) or has increased to approx. 0.5 micrometers (definitely so for the Pinatubo eruption of 1991). The reasons for this divergence in aerosol growth are unknown.

  10. In hot water: effects of temperature-dependent interiors on the radii of water-rich super-Earths

    NASA Astrophysics Data System (ADS)

    Thomas, Scott W.; Madhusudhan, Nikku

    2016-05-01

    Observational advancements are leading to increasingly precise measurements of super-Earth masses and radii. Such measurements are used in internal structure models to constrain interior compositions of super-Earths. It is now critically important to quantify the effect of various model assumptions on the predicted radii. In particular, models often neglect thermal effects, a choice justified by noting that the thermal expansion of a solid Earth-like planet is small. However, the thermal effects for water-rich interiors may be significant. We have systematically explored the extent to which thermal effects can influence the radii of water-rich super-Earths over a wide range of masses, surface temperatures, surface pressures and water mass fractions. We developed temperature-dependent internal structure models of water-rich super-Earths that include a comprehensive temperature-dependent water equation of state. We found that thermal effects induce significant changes in their radii. For example, for super-Earths with 10 per cent water by mass, the radius increases by up to 0.5 R⊕ when the surface temperature is increased from 300 to 1000 K, assuming a surface pressure of 100 bar and an adiabatic temperature gradient in the water layer. The increase is even larger at lower surface pressures and/or higher surface temperatures, while changing the water fraction makes only a marginal difference. These effects are comparable to current super-Earth radial measurement errors, which can be better than 0.1 R⊕. It is therefore important to ensure that the thermal behaviour of water is taken into account when interpreting super-Earth radii using internal structure models.

  11. Crystallization of confined water pools with radii greater than 1 nm in AOT reverse micelles.

    PubMed

    Suzuki, Akira; Yui, Hiroharu

    2014-07-01

    Freezing of water pools inside aerosol sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles has been investigated. Previous freezing experiments suffer from collision and fusion of AOT micelles and resultant loss of water from the water pool by shedding out during the cooling process. These phenomena have restricted the formation of ice to only when the radius of the water pool (Rw) is below 1 nm, and only amorphous ice has been observed. To overcome the size limitation, a combination of rapid cooling and a custom-made cell allowing thin sample loading is applied for instantaneous and homogeneous freezing. The freezing process is monitored with attenuated total reflection infrared spectroscopy (ATR-IR) measurements. A cooling rate of ca. -100 K/min and a sample thickness of ca. 50 μm overcomes the limitations mentioned above and allows the crystallization of water pools with larger radii (Rw > 1 nm). The corresponding ATR-IR spectra of the frozen water pools with Rw < 2.0 nm show similar features to the spectrum of metastable cubic ice (Ic). Further increase of the radius of the water pool (Rw > 2.0 nm), unfortunately, drastically decreased the integrated area of the ν(OH) band observed just after freezing, indicating the breakup of the micellar structure and shedding out of the water pool. In addition, it was revealed that Ic ice can also be formed in flexible organic self-assembled AOT reverse micelles for at least Rw ≤ ca. 2 nm, as well as in inorganic and solid materials with a pore radius of ca. 2 nm. The dependence of the phase transition temperature on the curvature of the reverse micelles is discussed from the viewpoint of the Gibbs-Thomson effect. PMID:24885023

  12. THE INNERMOST COLLIMATION STRUCTURE OF THE M87 JET DOWN TO ∼10 SCHWARZSCHILD RADII

    SciTech Connect

    Hada, Kazuhiro; Giroletti, Marcello; Giovannini, Gabriele; Kino, Motoki; Doi, Akihiro; Nagai, Hiroshi; Honma, Mareki; Hagiwara, Yoshiaki; Kawaguchi, Noriyuki

    2013-09-20

    We investigated the detailed inner jet structure of M87 using Very Long Baseline Array data at 2, 5, 8.4, 15, 23.8, 43, and 86 GHz, especially focusing on the multi-frequency properties of the radio core at the jet base. First, we measured the size of the core region transverse to the jet axis, defined as W{sub c}, at each frequency ν, and found a relation between W{sub c} and ν: W{sub c}(ν)∝ν{sup –0.71±0.05}. Then, by combining W{sub c}(ν) and the frequency dependence of the core position r{sub c}(ν), which was obtained in our previous study, we constructed a collimation profile of the innermost jet W{sub c}(r) down to ∼10 Schwarzschild radii (R{sub s}) from the central black hole. We found that W{sub c}(r) smoothly connects with the width profile of the outer edge-brightened, parabolic jet and then follows a similar radial dependence down to several tens of R{sub s}. Closer to the black hole, the measured radial profile suggests a possible change in the jet collimation shape from the outer parabolic one, where the jet shape tends to become more radially oriented. This result could be related to a magnetic collimation process or/and interactions with surrounding materials at the jet base. The present results shed light on the importance of higher-sensitivity/resolution imaging studies of M87 at 86, 43, and 22 GHz; these studies should be examined more rigorously.

  13. Fabrication of large radii toroidal surfaces by single point diamond turning

    SciTech Connect

    Cunningham, J.P.; Marlar, T.A.; Miller, A.C.; Paterson, R. L.

    1995-12-31

    An unconventional machining technique has been developed for producing relatively large radii quasi-toroidal surfaces which could not normally be produced by conventional diamond turning technology. The maximum radial swing capacity of a diamond turning lathe is the limiting factor for the rotational radius of any toroid. A typical diamond turned toroidal surface is produced when a part is rotated about the spindle axis while the diamond tool contours the surface with any curved path. Toric surfaces sliced horizontally, have been used in laser resonator cavities. This paper will address the fabrication of a special case of toroids where a rotating tool path is a circle whose center is offset from the rotational axis of the toroid by a distance greater than the minor radius of the tool path. The quasi-toroidal surfaces produced by this technique approximate all asymmetrical combinations of concave/convex section of a torus. Other machine configurations have been reported which offer alternative approaches to the fabrication of concave asymmetric aspheric surfaces. Prototypes of unique lenses each having two quasi-toroidal surfaces were fabricated in the Ultraprecision Manufacturing Technology Center at form key components of a scanned laser focusing system. As an example of the problem faced, the specifications for one of the surfaces was equivalent to a section of a torus with a two meter diameter hole. The lenses were fabricated on a Nanoform 600 diamond turning lathe. This is a numerically controlled two axis T-base lathe with an air bearing spindle and oil hydrostatic slides. The maximum radial swing for this machine is approximately 0.3 meters.

  14. Two-Particle Interferometry of 200 GeV Au+Au Collisions at PHENIX

    SciTech Connect

    Heffner, M

    2004-04-19

    The PHENIX experiment has measured pion-pion, kaon-kaon, and proton-proton correlations in Au+Au collisions at {radical}S{sub NN} = 200GeV. The correlations are fit to extract radii using both the Bowler Coulomb correction and full calculation of the two-particle wave function. The resulting radii are similar for all three species and decrease with increasing k{sub t} as expected for collective flow. The R{sub out} and R{sub side} radii are approximately equal indicating a short emission duration.

  15. The Gaia-ESO Survey: Stellar radii in the young open clusters NGC 2264, NGC 2547, and NGC 2516

    NASA Astrophysics Data System (ADS)

    Jackson, R. J.; Jeffries, R. D.; Randich, S.; Bragaglia, A.; Carraro, G.; Costado, M. T.; Flaccomio, E.; Lanzafame, A. C.; Lardo, C.; Monaco, L.; Morbidelli, L.; Smiljanic, R.; Zaggia, S.

    2016-02-01

    Context. Rapidly rotating, low-mass members of eclipsing binary systems have measured radii that are significantly larger than predicted by standard evolutionary models. It has been proposed that magnetic activity is responsible for this radius inflation. Aims: By estimating the radii of low-mass stars in three young clusters (NGC 2264, NGC 2547, NGC 2516, with ages of ~5, ~35 and ~140 Myr respectively), we aim to establish whether similar radius inflation is seen in single, magnetically active stars. Methods: We use radial velocities from the Gaia-ESO Survey (GES) and published photometry to establish cluster membership and then combine GES measurements of projected equatorial velocities with published rotation periods to estimate the average radii for groups of fast-rotating cluster members as a function of their luminosity and age. The average radii are compared with the predictions of both standard evolutionary models and variants that include magnetic inhibition of convection and starspots. Results: At a given luminosity, the stellar radii in NGC 2516 and NGC 2547 are larger than predicted by standard evolutionary models at the ages of these clusters. The discrepancy is least pronounced and not significant (≃10 per cent) in zero age main sequence stars with radiative cores, but more significant in lower-mass, fully convective pre main-sequence cluster members, reaching ≃30 ± 10 per cent. The uncertain age and distance of NGC 2264 preclude a reliable determination of any discrepancy for its members. Conclusions: The median radii we have estimated for low-mass fully convective stars in the older clusters are inconsistent (at the 2-3σ level) with non-magnetic evolutionary models and more consistent with models that incorporate the effects of magnetic fields or dark starspots. The available models suggest this requires either surface magnetic fields exceeding 2.5 kG, spots that block about 30 per cent of the photospheric flux, or a more moderate combination

  16. Masses and Charge Radii of {sup 17-22}Ne and the Two-Proton-Halo Candidate {sup 17}Ne

    SciTech Connect

    Geithner, W.; Kappertz, S.; Keim, M.; Neugart, R.; Wilbert, S.; Neff, T.; Feldmeier, H.; Herfurth, F.; Yazidjian, C.; Audi, G.; Guenaut, C.; Lunney, D.; Blaum, K.; George, S.; Delahaye, P.; Kellerbauer, A.; Kowalska, M.; Herlert, A.; Kluge, H.-J.; Lievens, P.

    2008-12-19

    High-precision mass and charge radius measurements on {sup 17-22}Ne, including the proton-halo candidate {sup 17}Ne, have been performed with Penning trap mass spectrometry and collinear laser spectroscopy. The {sup 17}Ne mass uncertainty is improved by factor 50, and the charge radii of {sup 17-19}Ne are determined for the first time. The fermionic molecular dynamics model explains the pronounced changes in the ground-state structure. It attributes the large charge radius of {sup 17}Ne to an extended proton configuration with an s{sup 2} component of about 40%. In {sup 18}Ne the smaller radius is due to a significantly smaller s{sup 2} component. The radii increase again for {sup 19-22}Ne due to cluster admixtures.

  17. Charge Radii and Electromagnetic Moments of Li and Be Isotopes from the Ab Initio No-Core Shell Model

    SciTech Connect

    Forssen, C; Caurier, E; Navratil, P

    2008-12-23

    Recently, charge radii and ground-state electromagnetic moments of Li and Be isotopes were measured precisely. We have performed large-scale ab initio no-core shell model calculations for these isotopes using high-precision nucleon-nucleon potentials. Our computed charge radii, quadrupole and magnetic-dipole moments are in a good agreement with the measurements with the exception of the {sup 11}Li charge radius. The overall trends of all observables are well reproduced. The magnetic moments are in particular well described. Also, we are able to reproduce the small magnitude of the {sup 6}Li quadrupole moment and with the CD-Bonn NN potential also its correct sign.

  18. Mercator maps of orientations of a C60 molecule in single-walled nanotubes with distinct radii

    SciTech Connect

    Michel, K.H.; Verberck, B.; Nikolaev, A.V.

    2005-09-27

    We study the confinement of a C60 molecule encapsulated in a cylindrical nanotube as a function of the tube radius. Drawing the Mercator maps of the potential, we find two distinct molecular orientations; for tubes with small radii, RT < or approx. 7 A, a fivefold axis of the molecule coincides with the tube long axis, for larger radii, RT > or approx. 8 A, a threefold axis of the molecule coincides with the tube long axis. These different orientations are caused by the relative importance of the repulsive and the attractive parts of the van der Waals potentials of the molecule with the tube wall for small and large tubes respectively. Experimental evidence is provided by the apparent splitting of Ag modes of the C60 molecule in resonant Raman scattering.

  19. Proton radii of {sup 4,6,8}He isotopes from high-precision nucleon-nucleon interactions

    SciTech Connect

    Caurier, E.; Navratil, P.

    2006-02-15

    Recently, precision laser spectroscopy on {sup 6}He atoms determined accurately the isotope shift between {sup 4}He and {sup 6}He and, consequently, the charge radius of {sup 6}He. A similar experiment for {sup 8}He is under way. We have performed large-scale ab initio calculations for {sup 4,6,8}He isotopes using high-precision nucleon-nucleon (NN) interactions within the no-core shell model (NCSM) approach. With the CD-Bonn 2000 NN potential we found point-proton root-mean-square (rms) radii of {sup 4}He and {sup 6}He 1.45(1) fm and 1.89(4), respectively, in agreement with experiment and predict the {sup 8}He point-proton rms radius to be 1.88(6) fm. At the same time, our calculations show that the recently developed nonlocal INOY NN potential gives binding energies closer to experiment, but underestimates the charge radii.

  20. Charge radii and electromagnetic moments of Li and Be isotopes from the ab initio no-core shell model

    SciTech Connect

    Forssen, C.; Caurier, E.; Navratil, P.

    2009-02-15

    Recently, charge radii and ground-state electromagnetic moments of Li and Be isotopes were measured precisely. We have performed large-scale ab initio no-core shell model calculations for these isotopes using high-precision nucleon-nucleon potentials. The isotopic trends of our computed charge radii and quadrupole and magnetic-dipole moments are in good agreement with experimental results with the exception of the {sup 11}Li charge radius. The magnetic moments are in particular well described, whereas the absolute magnitudes of the quadrupole moments are about 10% too small. The small magnitude of the {sup 6}Li quadrupole moment is reproduced, and with the CD-Bonn NN potential, also its correct sign.

  1. A Hard Look at Neutron Star Radii and Disks with XMM-Newton and NuSTAR

    NASA Astrophysics Data System (ADS)

    Miller, Jon

    2013-10-01

    We request 40 ks observations of Cygnus X-2, 4U 1636-53, GX 17+2 and 4U 1705-44, jointly with XMM-Newton and NuSTAR. The primary goals are to test the ubiquity of relativistic lines in "Z" and "atoll" sources, and to obtain constraints on stellar radii and/or inner disk radii in cases where relativistic lines are found. With NuSTAR as a guide, we will determine when pile-up has been removed from the EPIC-pn ``timing'' mode observations via the exclusion of central pixels. We can then fully leverage the superior resolution of the EPIC-pn in the Fe K band in order to check for ionized disk winds that could distort disk reflection. The low energy coverage of XMM-Newton will give the best possible contraints on the direct continuum and the neutral line-of-sight absorption.

  2. Distribution over pore radii in random and isotropic systems of polydisperse rods with finite aspect ratios

    NASA Astrophysics Data System (ADS)

    Chatterjee, Avik P.

    2016-06-01

    Excluded-volume arguments are applied toward modeling the pore-size distribution in systems of randomly arranged cylindrical rods with finite and nonuniform aspect ratios. An explicit expression for the pore-size distribution is obtained by way of an analogy to a hypothetical system of fully penetrable objects, through a mapping that is designed to preserve the volume fraction occupied by the particle cores and the specific surface area. Results are presented for the mean value and standard deviation of the pore radius as functions of the rod aspect ratio, volume fraction, and polydispersity (degree of nonuniformity in the aspect ratios of the particles).

  3. On neutron stars in f(R) theories: Small radii, large masses and large energy emitted in a merger

    NASA Astrophysics Data System (ADS)

    Aparicio Resco, Miguel; de la Cruz-Dombriz, Álvaro; Llanes Estrada, Felipe J.; Zapatero Castrillo, Víctor

    2016-09-01

    In the context of f(R) gravity theories, we show that the apparent mass of a neutron star as seen from an observer at infinity is numerically calculable but requires careful matching, first at the star's edge, between interior and exterior solutions, none of them being totally Schwarzschild-like but presenting instead small oscillations of the curvature scalar R; and second at large radii, where the Newtonian potential is used to identify the mass of the neutron star. We find that for the same equation of state, this mass definition is always larger than its general relativistic counterpart. We exemplify this with quadratic R2 and Hu-Sawicki-like modifications of the standard General Relativity action. Therefore, the finding of two-solar mass neutron stars basically imposes no constraint on stable f(R) theories. However, star radii are in general smaller than in General Relativity, which can give an observational handle on such classes of models at the astrophysical level. Both larger masses and smaller matter radii are due to much of the apparent effective energy residing in the outer metric for scalar-tensor theories. Finally, because the f(R) neutron star masses can be much larger than General Relativity counterparts, the total energy available for radiating gravitational waves could be of order several solar masses, and thus a merger of these stars constitutes an interesting wave source.

  4. The stellar accretion origin of stellar population gradients at large radii in massive, early-type galaxies

    NASA Astrophysics Data System (ADS)

    Hirschmann, Michaela; Naab, Thorsten

    2015-08-01

    We investigate the differential impact of physical mechanisms, mergers (stellar accretion) and internal energetic phenomena, on the evolution of stellar population gradients in massive, present-day galaxies employing a set of high-resolved, cosmological zoom simulations. We demonstrate that negative metallicity and color gradients at large radii (>2Reff) originate from the accretion of metal-poor stellar systems. At larger radii, galaxies become typically more dominated by stars accreted from satellite galaxies in major and minor mergers. However, only strong galactic winds can sufficiently reduce the metallicity content of the accreted stars to realistically steepen the outer metallicity and colour gradients in agreement with present-day observations. In contrast, the gradients of the models without winds are inconsistent with observations (too flat). In the wind model, colour and metallicity gradients are significantly steeper for systems which have accreted stars in minor mergers, while galaxies with major mergers have relatively flat gradients, confirming previous results. This analysis greatly highlights the importance of both energetic processes and merger events for stellar population properties of massive galaxies at large radii. Our results are expected to significantly contribute to the interpretation of current and up-coming IFU surveys (like MaNGA and Califa), which in turn can help to constrain models for energetic processes in simulations.

  5. Isotope-shift measurements of stable and short-lived lithium isotopes for nuclear-charge-radii determination

    SciTech Connect

    Noertershaeuser, W.; Sanchez, R.; Ewald, G.; Dax, A.; Goette, S.; Kluge, H.-J.; Kuehl, Th.; Wojtaszek, A.; Behr, J.; Bricault, P.; Dilling, J.; Dombsky, M.; Lassen, J.; Levy, C. D. P.; Pearson, M.; Bushaw, B. A.; Drake, G. W. F.; Pachucki, K.; Puchalski, M.; Yan, Z.-C.

    2011-01-15

    Changes in the mean square nuclear charge radii along the lithium isotopic chain were determined using a combination of precise isotope shift measurements and theoretical atomic structure calculations. Nuclear charge radii of light elements are of high interest due to the appearance of the nuclear halo phenomenon in this region of the nuclear chart. During the past years we have developed a laser spectroscopic approach to determine the charge radii of lithium isotopes which combines high sensitivity, speed, and accuracy to measure the extremely small field shift of an 8-ms-lifetime isotope with production rates on the order of only 10 000 atoms/s. The method was applied to all bound isotopes of lithium including the two-neutron halo isotope {sup 11}Li at the on-line isotope separators at GSI, Darmstadt, Germany, and at TRIUMF, Vancouver, Canada. We describe the laser spectroscopic method in detail, present updated and improved values from theory and experiment, and discuss the results.

  6. Slow viscous flow of two particles in a cylindrical tube

    NASA Astrophysics Data System (ADS)

    Yao, Xin; Wong, Teck Neng; Marcos, -

    2015-11-01

    The slow viscous flow around two particles in a cylindrical tube is obtained theoretically. We employ the Lamb's general solution based on spherical harmonics and cylindrical harmonics to solve the flow field around the particles and the flow within the tube, respectively. We compute the drag and torque coefficients of the particles which are dependent on the distance among the cylinder wall and the two particles. The hydrodynamic forces are also a function of particle velocities and background velocity. Our results are in agreement with the existing theory of a single particle traveling in the tube when the distance between the two particles increases. We found that particle-particle interactions can be neglected when the separation distance is three times larger than the sum of particles radii. Furthermore, such analysis can give us insights to understand the mechanisms of collision and aggregation of particles.

  7. Determination of Particle Size by Diffraction of Light

    ERIC Educational Resources Information Center

    Rinard, Phillip M.

    1974-01-01

    Describes a simplified diffraction experiment offered in a workshop with the purpose of illustrating to high school students the relation of science to society. The radii determined for cigarette smoke particles range from 0.2 to 0.5 micrometer in this experiment. Included is a description of the diffraction theory. (CC)

  8. Observations of solar energetic particles at a synchronous orbit

    NASA Technical Reports Server (NTRS)

    Takenaka, T.; Ohi, Y.; Yanagimachi, T.; Ito, K.; Kohno, T.; Sakurai, K.

    1985-01-01

    The Space Environment Monitors (SEM) on board the Japanese geostationary meteorological satellites (GMS-1 and GMS-2) observed energetic protons, alpha particles and electrons continuously for February 1978 to September 1984. The satellites were at 6.6 Earth radii above 140 deg E equator.

  9. Carbon dust particle size distributions around mass-losing AGB stars

    NASA Astrophysics Data System (ADS)

    Jura, M.

    1997-03-01

    Solids of presolar SiC and interstellar carbon have qualitatively similar relative size distribution for particles with radii, a, in the range 0.35 μmparticles. The close binary system, the Red Rectangle, appears to produce much larger grains than does IRC+10216, and we suggest that many of the interstellar and presolar particles with radii >0.35 μm are produced by interacting binary systems rather than single mass-losing stars.

  10. Optical trapping and manipulation of Mie particles with Airy beam

    NASA Astrophysics Data System (ADS)

    Zhao, Ziyu; Zang, Weiping; Tian, Jianguo

    2016-02-01

    In this paper we calculate the radiation forces and moving trajectories of Mie particles induced by 1D Airy beams using the plane wave spectrum method and arbitrary beam theory. Numerical results show that both the transverse and the longitudinal radiation forces are deeply dependent on the relative refractive index, radii and positions of the scattering particles illuminated by the Airy beam. Due to the radiation forces, Mie particles with different radii and initial positions can be dragged into the nearest main intensity lobes, and move along parabolic trajectories in the direction of the Poynting vector. At the ends of these trajectories, in the presence of Brownian force, the trapped scattering particles show irregular Brownian movement near their equilibrium positions. This characteristic property of Airy beams enables optical sorting to be used more easily in the colloidal and biological sciences.

  11. Stellar envelope inflation near the Eddington limit. Implications for the radii of Wolf-Rayet stars and luminous blue variables

    NASA Astrophysics Data System (ADS)

    Gräfener, G.; Owocki, S. P.; Vink, J. S.

    2012-02-01

    Context. It has been proposed that the envelopes of luminous stars may be subject to substantial radius inflation. The peculiar structure of such inflated envelopes, with an almost void, radiatively dominated region beneath a thin, dense shell could mean that many in reality compact stars are hidden below inflated envelopes, displaying much lower effective temperatures. The inflation effect has been discussed in relation to the radius problem of Wolf-Rayet (WR) stars, but has yet failed to explain the large observed radii of Galactic WR stars. Aims: We wish to obtain a physical perspective of the inflation effect, and study the consequences for the radii of WR stars, and luminous blue variables (LBVs). For WR stars the observed radii are up to an order of magnitude larger than predicted by theory, whilst S Doradus-type LBVs are subject to humongous radius variations, which remain as yet ill-explained. Methods: We use a dual approach to investigate the envelope inflation, based on numerical models for stars near the Eddington limit, and a new analytic formalism to describe the effect. An additional new aspect is that we take the effect of density inhomogeneities (clumping) within the outer stellar envelopes into account. Results: Due to the effect of clumping we are able to bring the observed WR radii in agreement with theory. Based on our new formalism, we find that the radial inflation is a function of a dimensionless parameter W, which largely depends on the topology of the Fe-opacity peak, i.e., on material properties. For W > 1, we discover an instability limit, for which the stellar envelope becomes gravitationally unbound, i.e. there no longer exists a static solution. Within this framework we are also able to explain the S Doradus-type instabilities for LBVs like AG Car, with a possible triggering due to changes in stellar rotation. Conclusions: The stellar effective temperatures in the upper Hertzsprung-Russell (HR) diagram are potentially strongly affected

  12. Ionization potentials, electron affinities, resonance excitation energies, oscillator strengths, and ionic radii of element Uus (Z = 117) and astatine.

    PubMed

    Chang, Zhiwei; Li, Jiguang; Dong, Chenzhong

    2010-12-30

    Multiconfiguration Dirac-Fock (MCDF) method was employed to calculate the first five ionization potentials, electron affinities, resonance excitation energies, oscillator strengths, and radii for the element Uus and its homologue At. Main valence correlation effects were taken into account. The Breit interaction and QED effects were also estimated. The uncertainties of calculated IPs, EAs, and IR for Uus and At were reduced through an extrapolation procedure. The good consistency with available experimental and other theoretical values demonstrates the validity of the present results. These theoretical data therefore can be used to predict some unknown physicochemical properties of element Uus, Astatine, and their compounds. PMID:21141866

  13. Geophysical disturbance environment during the NASA/MPE barium release at 5 earth radii on September 21, 1971.

    NASA Technical Reports Server (NTRS)

    Davis, T. N.; Stanley, G. M.; Boyd, J. S.

    1973-01-01

    The geophysical disturbance environment was quiet during the NASA/MPE barium release at 5 earth radii on September 21, 1971. At the time of the release, the magnetosphere was in the late recovery phase of a principal magnetic storm, the provisional Dst value was -13 gammas, and the local horizontal disturbance at Great Whale River was near zero. Riometer and other observations indicated low-level widespread precipitation of high-energy electrons at Great Whale River before, during, and after the release. Cloudy sky at this station prevented optical observation of aurora. No magnetic or ionospheric effects attributable to the barium release were detected at Great Whale River.

  14. PROBA2/SWAP EUV images of the large-scale EUV corona up to 3 solar radii: Can we close the gap in coronal magnetic field structure between 1.3 and 2.5 solar radii?

    NASA Astrophysics Data System (ADS)

    De Groof, Anik; Seaton, Daniel B.; Rachmeler, Laurel; Berghmans, David

    2015-04-01

    The EUV telescope PROBA2/SWAP has been observing the solar corona in a bandpass near 17.4 nm since February 2010. SWAP's wide field-of-view provides a unique and continuous view of the extended EUV corona up to 2-3 solar radii. By carefully processing and combining multiple SWAP images, low-noise composites were produced that reveal large-scale, EUV-emitting, coronal structures. These extended structures appear mainly above or at the edges of active regions and typically curve towards the poles. As they persist for multiple Carrington rotations and cannot easily be related to white-light features, they give an interesting view on how the coronal magnetic field is structured between 1.3 and 2-3 solar radii, in the gap between SDO/AIA’s FOV and typical lower boundaries of coronagraph FOVs. With the help of magnetic field models, we analyse the geometry of the extended EUV structures in more detail and compare with sporadic EUV coronagraph measurements up to as close as 1.5Rs. The opportunities that Solar Orbiter’s future observations will bring are explored.

  15. Tentative study of nuclear charge radii for neutron-deficient nuclei around the Z = 82 shell from experimental α decay data

    NASA Astrophysics Data System (ADS)

    Qian, Yibin; Ren, Zhongzhou

    2016-01-01

    We tentatively investigate the root-mean-square (rms) nuclear charge radii of odd-A Po and Pb isotopes plus Tl isotopes, particularly concerning these difficultly-detected nuclei along with short lifetimes, via various data on α decay. Within the density-dependent cluster model, the density distributions of studied daughter nuclei are determined by exactly reproducing the corresponding experimental α decay half-lives, which leads the final results of nuclear charge radii. In addition, our recently proposed formula deducing the charge radii is extended to this study for comparison. Whether it concerns the ground or isomeric state of target nuclei, the extracted nuclear charge radii are found to be in good agreement with the measured values. Sequential predictions on the rms charge radii are subsequently made for these neutron-deficient nuclei and especially for the rarely detected Bi isotopic chain, which are expected to be useful for future measurements. Moreover, the variety of α-preformation factors is analyzed in the scheme of valence nucleon number to pursue the further improvement of the model. This may be considered as an effective effort to obtain the charge radii of ground and even low-lying excited states for exotic nuclei near the proton-dripline.

  16. A simple rotational pendulum method to measure the radii of gyration or mass moments of inertia of a rotor and other assemblies

    SciTech Connect

    Andriulli, J.B.

    1997-01-01

    In mechanical dynamic problems, it is often necessary to know the radii of gyration or equivalent mass moments of inertia of components and assemblies. Using the rotational pendulum technique described, one can easily measure the radii of gyration about the polar and diametric axes of any rigid rotor without requiring a special fixture. The principals employed are also applicable to more complicated assemblies such as aircraft, boats, and cars, where the radius of gyration and vehicle maneuverability are of interest. This description focuses on rotors. The relative values of polar and diametric radii of gyration characterize some dynamic behavior and stability of spinning rotors. When the ratio of polar to diametric radii of gyration approaches unity, the spinning rotor may exhibit undesirable dynamic behavior. Consequently, prior to high-speed spin testing the rotor or otherwise operating the assembly, it is desirable to have a simple and inexpensive procedure to directly measure the radii of gyration of existing hardware. These data permit the technician to estimate the rotor dynamic behavior or identify potential problems prior to committing to operation. If sufficient part information is available, such as dimensions, geometry and material density, one can calculate the radii of gyration. For complicated parts, this can be time consuming. Often the technician does not have access to the rotor`s dimensional details to make the calculations. Hence, an inexpensive empirical technique such as the one described is valuable.

  17. Centrality dependence of pion freeze-out radii in Pb-Pb collisions at √{sN N}=2.76 TeV

    NASA Astrophysics Data System (ADS)

    Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahn, S. U.; Aimo, I.; Aiola, S.; Ajaz, M.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Almaraz, J. R. M.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Armesto, N.; Arnaldi, R.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Bach, M.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Baltasar Dos Santos Pedrosa, F.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Belyaev, V.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biswas, R.; Biswas, S.; Bjelogrlic, S.; Blair, J. T.; Blanco, F.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botta, E.; Böttger, S.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Carnesecchi, F.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Cavicchioli, C.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Cerkala, J.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Chunhui, Z.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa Del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; de, S.; de Caro, A.; de Cataldo, G.; de Cuveland, J.; de Falco, A.; de Gruttola, D.; De Marco, N.; de Pasquale, S.; Deisting, A.; Deloff, A.; Dénes, E.; D'Erasmo, G.; di Bari, D.; di Mauro, A.; di Nezza, P.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Dobrowolski, T.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Drozhzhova, T.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Engel, H.; Erazmus, B.; Erdemir, I.; Erhardt, F.; Eschweiler, D.; Espagnon, B.; Estienne, M.; Esumi, S.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Felea, D.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fiore, E. M.; Fleck, M. G.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Germain, M.; Gheata, A.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Graczykowski, L. K.; Graham, K. L.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gulkanyan, H.; Gunji, T.; Gupta, A.; Gupta, R.; Haake, R.

    2016-02-01

    We report on the measurement of freeze-out radii for pairs of identical-charge pions measured in Pb-Pb collisions at √{sNN}=2.76 TeV as a function of collision centrality and the average transverse momentum of the pair kT. Three-dimensional sizes of the system (femtoscopic radii), as well as direction-averaged one-dimensional radii are extracted. The radii decrease with kT, following a power-law behavior. This is qualitatively consistent with expectations from a collectively expanding system, produced in hydrodynamic calculations. The radii also scale linearly with 1 /3. This behavior is compared to world data on femtoscopic radii in heavy-ion collisions. While the dependence is qualitatively similar to results at smaller √{sNN}, a decrease in the ratio Rout/Rside is seen, which is in qualitative agreement with a specific prediction from hydrodynamic models: a change from inside-out to outside-in freeze-out configuration. The results provide further evidence for the production of a collective, strongly coupled system in heavy-ion collisions at the CERN Large Hadron Collider.

  18. A New Semi-Empirical Technique For Computing Effective Temperatures For Main Sequence Stars From Their Mass And Radii

    NASA Astrophysics Data System (ADS)

    Aslan, Gürkan; Soydugan, Faruk; Eker, Zeki; Bilir, Selçuk; Bakış, Volkan

    2016-07-01

    A semi-empirical technique of improving effective temperature for main sequence stars from their observed mass and radius based on the Stefan-Boltzmann law, was introduced and applied to 450 main-sequence stars with accurate parameters. The method requires a mass-luminosity relation (MLR) and theoretical predictions of radius and effective temperature for stars at zero age main-sequence and at terminal age main-sequence. The MLRs, which act as if a catalyst, are necessary but have no effect on the final result. The present sample of main-sequence stars, which are members of the detached double-lined eclipsing binaries in the solar neighborhood chosen from Eker et al. (2014), have an error histogram for the observed effective temperatures with a peak at 2-3%. Errors of refined effective temperatures by the present method are the propagated errors of the observed masses and radii, that is, the refined temperatures and associated errors are independent of the observational temperatures and their associated errors. The histogram of the refined temperature errors shows a peak at less than 1%. A refined sample of stars (270 out of 450) with masses and radii accurate up to 3% and their refined effective temperatures has been used in this study to improve the classical MLRs. One may prefer, however, to use improved classical MLRs, which allows one to compute effective temperatures as accurate as 3.5%.

  19. Constructing a statistical atlas of the radii of the optic nerve and cerebrospinal fluid sheath in young healthy adults

    NASA Astrophysics Data System (ADS)

    Harrigan, Robert L.; Plassard, Andrew J.; Mawn, Louise A.; Galloway, Robert L.; Smith, Seth A.; Landman, Bennett A.

    2015-03-01

    Optic neuritis is a sudden inflammation of the optic nerve (ON) and is marked by pain on eye movement, and visual symptoms such as a decrease in visual acuity, color vision, contrast and visual field defects. The ON is closely linked with multiple sclerosis (MS) and patients have a 50% chance of developing MS within 15 years. Recent advances in multi-atlas segmentation methods have omitted volumetric assessment. In the past, measuring the size of the ON has been done by hand. We utilize a new method of automatically segmenting the ON to measure the radii of both the ON and surrounding cerebrospinal fluid (CSF) sheath to develop a normative distribution of healthy young adults. We examine this distribution for any trends and find that ON and CSF sheath radii do not vary between 20-35 years of age and between sexes. We evaluate how six patients suffering from optic neuropathy compare to this distribution of controls. We find that of these six patients, five of them qualitatively differ from the normative distribution which suggests this technique could be used in the future to distinguish between optic neuritis patients and healthy controls

  20. Saturn's rings - Particle size distributions for thin layer model

    NASA Technical Reports Server (NTRS)

    Zebker, H. A.; Marouf, E. A.; Tyler, G. L.

    1985-01-01

    A model incorporating limited interaction between the incident energy and particles in the ring is considered which appears to be consistent with the multiple scattering process in Saturn's rings. The model allows for the small physical thickness of the rings and can be used to relate Voyager 1 observations of 3.6- and 13-cm wavelength microwave scatter from the rings to the ring particle size distribution function for particles with radii ranging from 0.001 to 20 m. This limited-scatter model yields solutions for particle size distribution functions for eight regions in the rings, which exhibit approximately inverse-cubic power-law behavior.

  1. Particle Acceleration in the Low Corona Over Broad Longitudes: Coupling MHD and 3D Particle Simulations

    NASA Astrophysics Data System (ADS)

    Gorby, M.; Schwadron, N.; Torok, T.; Downs, C.; Lionello, R.; Linker, J.; Titov, V. S.; Mikic, Z.; Riley, P.; Desai, M. I.; Dayeh, M. A.

    2014-12-01

    Recent work on the coupling between the Energetic Particle Radiation Environment Module (EPREM, a 3D energetic particle model) and Magnetohydrodynamics Around a Sphere (MAS, an MHD code developed at Predictive Science, Inc.) has demonstrated the efficacy of compression regions around fast coronal mass ejections (CMEs) for particle acceleration low in the corona (˜ 3 - 6 solar radii). These couplings show rapid particle acceleration over a broad longitudinal extent (˜ 80 degrees) resulting from the pile-up of magnetic flux in the compression regions and their subsequent expansion. The challenge for forming large SEP events in such compression-acceleration scenarios is to have enhanced scattering within the acceleration region while also allowing for efficient escape of accelerated particles downstream (away from the Sun) from the compression region. We present here the most recent simulation results including energetic particle and CME plasma profiles, the subsequent flux and dosages at 1AU, and an analysis of the compressional regions as efficient accelerators.

  2. Moment of inertia, radii, surface emission from a new theoretical understanding of Neutron Stars

    NASA Astrophysics Data System (ADS)

    Belvedere, Riccardo; Ruffini, Remo; Xue, She-Sheng; Rueda Hernandez, Jorge Armando

    2012-07-01

    We formulate the equations of neutron stars taking into account the strong, weak, electromagnetic and gravitational interactions within a new fully general relativistic Thomas-Fermi approach. The nuclear interactions are described by the exchange of the sigma, omega, and rho virtual mesons. The constancy of the generalized chemical potential, for short Klein potentials, of the particle species is required as a condition of equilibrium throughout the star. The continuity of the Klein potentials in the transition from the core to the crust imposes the presence of a strong electric field larger than the critical one for vacuum polarization. Correspondingly, the electron density decreases in the core-crust transition region. Such a phenomenon leads to neutron stars with crusts with masses and thickness smaller with respect to the ones of traditional neutron star configurations that satisfy local charge neutrality from the center all the way up to the surface. We present new estimates of the mass-radius relation, moment of inertia, quadrupole moment, and period of rotation of neutron stars. The consequences on the emission process and timing properties of neutron stars, as well as the possible consequences on QPO emission, are considered.

  3. Nightside energetic particle decreases at the synchronous orbit

    NASA Technical Reports Server (NTRS)

    Bogott, F. H.

    1973-01-01

    More than 100 cases of major decreases of proton and electron fluxes at the synchronous orbit have been observed and interpreted as a movement of the energetic particle trapping boundary earthward of 6.6 earth radii before the substorm expansion phase. These events are observed only between 1700 and 0800 LT and are consistent with the existence of a westward magnetospheric electric field of a few tenths of a millivolt per meter before substorm expansion. Most substorm particle events seen on the nightside do not exhibit this behavior, presumably because the trapping boundary moves inside 6.6 earth radii only during major events. Such events show evidence of particle acceleration, which probably was concentrated at higher L values, near the instantaneous location of the trapping boundary.

  4. Interaction of evaporating and condensing particles in the free-molecular regime

    NASA Astrophysics Data System (ADS)

    Kogan, M. N.; Bobrov, I. N.; Cercignani, C.; Frezzotti, A.

    1995-07-01

    In a previous paper it was shown that repulsive/attractive forces arise between evaporating/ condensing particles in the free-molecular regime. Here we obtain explicit expressions for these forces in the case of spherical particles with equal temperatures. The temperature of the surrounding vapor is, generally speaking, different from that of the particles. Numerical results are obtained for different values of the ratios between particle and vapor temperatures and pressures, of the particles radii and of the evaporation coefficients. In the case when the evaporation coefficient equals unity, an exact expression is obtained for the force between particles of different radii. A simple model describing coagulation processes and taking the above-mentioned forces into account is proposed. It is shown that for large values of the vapor supersaturation, the influence of these forces on the coagulation rate may be very pronounced.

  5. Interactions of charged dust particles in clouds of charges

    NASA Astrophysics Data System (ADS)

    Gundienkov, Vladimir; Yakovlenko, Sergey

    2004-03-01

    Two charged dust particles inside a cloud of charges are considered as Debye atoms forming a Debye molecule. Cassini coordinates are used for the numerical solution of the Poisson-Boltzmann equation for the charged cloud. The electric force acting on a dust particle by the other dust particle was determined by integrating the electrostatic pressure on the surface of the dust particle. It is shown that attractive forces appear when the following two conditions are satisfied. First, the average distance between dust particles should be approximately equal to two Debye radii. Second, attraction takes place when similar charges are concentrated predominantly on the dust particles. If the particles carry a small fraction of total charge of the same polarity, repulsion between the particles takes place at all distances. We apply our results to the experiments with thermoemission plasma and to the experiments with nuclear-pumped plasma.

  6. Detailed heat transfer coefficient measurements and thermal analysis at engine conditions of a pedestal with fillet radii

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Ireland, P. T.; Jones, T. V.

    1995-04-01

    The heat transfer coefficient over the surface of a pedestal with fillet radii has been measured using thermochromic liquid crystals and the transient heat transfer method. The tests were performed at engine representative Reynolds numbers for a geometry typical of those used in turbine blade cooling systems. The heat conduction process that occurs in the engine was subsequently modeled numerically with a finite element discretization of the solid pedestal. The measured heat transfer coefficients were used to derive the exact boundary conditions applicable to the engine. The temperature field within the pedestal, calculated using the correct heat transfer coefficient distribution, is compared to that calculated using an area-averaged heat transfer coefficient. Metal temperature differences of 90 K are predicted across the blade wall.

  7. Scaling of charge-changing interaction cross sections and point-proton radii of neutron-rich carbon isotopes.

    PubMed

    Yamaguchi, T; Hachiuma, I; Kitagawa, A; Namihira, K; Sato, S; Suzuki, T; Tanihata, I; Fukuda, M

    2011-07-15

    Charge-changing cross sections σ(cc) of stable and unstable nuclei ((9-11)Be, (14-16)C, and (16-18)O) on a carbon target were investigated at 300  MeV/nucleon. A phenomenological analysis based on the Glauber theory indicates an approximate, but universal, scaling of σ(cc) over a wide range of A/Z. This allows the determination of the density distributions of protons tightly bound in the nuclei. An application to (16)C, which is considered to be an anomalously deformed nucleus, indicates a systematic evolution of proton root-mean-square radii and has revealed for the first time a neutron skin effect in carbon isotopes. Being complementary to isotope-shift and electron-scattering experiments, the present method can open up a new approach to explore the structure of exotic nuclei. PMID:21838353

  8. Strange star equation of state fits the refined mass measurement of 12 pulsars and predicts their radii

    NASA Astrophysics Data System (ADS)

    Gangopadhyay, Taparati; Ray, Subharthi; Li, Xiang-Dong; Dey, Jishnu; Dey, Mira

    2013-06-01

    There are three categories of stars whose masses have been found accurately in recent times: (1) two for which Shapiro delay is used, which is possible due to GR light bending as the partner is heavy - PSR J1614-2230 and PSR J1903+0327, (2) six eclipsing stars for which numerical Roche lobe geometry is used and (3) three stars for which spectroscopic methods are used and in fact for these three the mass and radii both are estimated. Motivated by large colour (Nc) expansion using a modified Richardson potential, along with density-dependent quark masses thereby allowing chiral symmetry restoration, we get compact strange stars fitting all the observed masses.

  9. Synchrotron radiation from the winds of O supergiants - Tb = 10 to the 7. 6th K at 60 stellar radii

    SciTech Connect

    Phillips, R.B.; Titus, M.A. )

    1990-08-01

    Results are presented on VLBI measurements of the nonthermal radio components around two O supergiant stars: Cyg OB2 No. 9 and HD 167971. The measurements were used to characterize the brightness temperature of the emission and to measure the size of compact 5-10 mJy components in these stars, reported by Bieging et al. (1989). The sizes found for the 5-10 mJy components are consistent with the free-free wind radii, indicating that the compact companions are not the sources of nonthermal radiation. Results suggest that there is a small fractional population (10 to the -4th to 10 to the -7th) of ultrarelativistic electrons (Teff of about 10 to the 11th K) coexisting with the stellar wind, which emit optically thin synchrotron radiation. This is in agreement with the synchrotron model of White (1985). 21 refs.

  10. VR-SCOSMO: A smooth conductor-like screening model with charge-dependent radii for modeling chemical reactions

    NASA Astrophysics Data System (ADS)

    Kuechler, Erich R.; Giese, Timothy J.; York, Darrin M.

    2016-04-01

    To better represent the solvation effects observed along reaction pathways, and of ionic species in general, a charge-dependent variable-radii smooth conductor-like screening model (VR-SCOSMO) is developed. This model is implemented and parameterized with a third order density-functional tight binding quantum model, DFTB3/3OB-OPhyd, a quantum method which was developed for organic and biological compounds, utilizing a specific parameterization for phosphate hydrolysis reactions. Unlike most other applications with the DFTB3/3OB model, an auxiliary set of atomic multipoles is constructed from the underlying DFTB3 density matrix which is used to interact the solute with the solvent response surface. The resulting method is variational, produces smooth energies, and has analytic gradients. As a baseline, a conventional SCOSMO model with fixed radii is also parameterized. The SCOSMO and VR-SCOSMO models shown have comparable accuracy in reproducing neutral-molecule absolute solvation free energies; however, the VR-SCOSMO model is shown to reduce the mean unsigned errors (MUEs) of ionic compounds by half (about 2-3 kcal/mol). The VR-SCOSMO model presents similar accuracy as a charge-dependent Poisson-Boltzmann model introduced by Hou et al. [J. Chem. Theory Comput. 6, 2303 (2010)]. VR-SCOSMO is then used to examine the hydrolysis of trimethylphosphate and seven other phosphoryl transesterification reactions with different leaving groups. Two-dimensional energy landscapes are constructed for these reactions and calculated barriers are compared to those obtained from ab initio polarizable continuum calculations and experiment. Results of the VR-SCOSMO model are in good agreement in both cases, capturing the rate-limiting reaction barrier and the nature of the transition state.

  11. VR-SCOSMO: A smooth conductor-like screening model with charge-dependent radii for modeling chemical reactions.

    PubMed

    Kuechler, Erich R; Giese, Timothy J; York, Darrin M

    2016-04-28

    To better represent the solvation effects observed along reaction pathways, and of ionic species in general, a charge-dependent variable-radii smooth conductor-like screening model (VR-SCOSMO) is developed. This model is implemented and parameterized with a third order density-functional tight binding quantum model, DFTB3/3OB-OPhyd, a quantum method which was developed for organic and biological compounds, utilizing a specific parameterization for phosphate hydrolysis reactions. Unlike most other applications with the DFTB3/3OB model, an auxiliary set of atomic multipoles is constructed from the underlying DFTB3 density matrix which is used to interact the solute with the solvent response surface. The resulting method is variational, produces smooth energies, and has analytic gradients. As a baseline, a conventional SCOSMO model with fixed radii is also parameterized. The SCOSMO and VR-SCOSMO models shown have comparable accuracy in reproducing neutral-molecule absolute solvation free energies; however, the VR-SCOSMO model is shown to reduce the mean unsigned errors (MUEs) of ionic compounds by half (about 2-3 kcal/mol). The VR-SCOSMO model presents similar accuracy as a charge-dependent Poisson-Boltzmann model introduced by Hou et al. [J. Chem. Theory Comput. 6, 2303 (2010)]. VR-SCOSMO is then used to examine the hydrolysis of trimethylphosphate and seven other phosphoryl transesterification reactions with different leaving groups. Two-dimensional energy landscapes are constructed for these reactions and calculated barriers are compared to those obtained from ab initio polarizable continuum calculations and experiment. Results of the VR-SCOSMO model are in good agreement in both cases, capturing the rate-limiting reaction barrier and the nature of the transition state. PMID:27131539

  12. Time-averaged acoustic forces acting on a rigid sphere within a wide range of radii in an axisymmetric levitator

    NASA Astrophysics Data System (ADS)

    Foresti, Daniele; Nabavi, Majid; Poulikakos, Dimos

    2012-05-01

    Acoustic levitation is a physical phenomenon that arises when the acoustic radiation pressure is strong enough to overcome gravitational force. It is a nonlinear phenomenon which can be predicted only if higher order terms are included in the acoustic field calculation. The study of acoustic levitation is usually conducted by solving the linear acoustic equation and bridging the gap with an analytical solution. Only recently, the scientific community has shown interest in the full solution of the Navier-Stokes' equation with the aim of deeply investigating the acoustic radiation pressure. We present herein a numerical model based on Finite Volume Method (FVM) and Dynamic Mesh (DM) for the calculation of the acoustic radiation pressure acting on a rigid sphere inside an axisymmetric levitator which is the most widely used and investigated type of levitators. In this work, we focus on the third resonance mode. The use of DM is new in the field of acoustic levitation, allowing a more realistic simulation of the phenomenon, since no standing wave has to be necessarily imposed as boundary condition. The radiating plate is modeled as a rigid cylinder moving sinusoidally along the central axis. The time-averaged acoustic force exerting on the sphere is calculated for different radii Rs of the sphere (0.025 to 0.5 wavelengths). It is shown that the acoustic force increases proportional to Rs3 for small radii, then decreases when the standing wave condition is violated and finally rises again in the travelling wave radiation pressure configuration. The numerical model is validated for the inviscid case with a Finite Element Method model of the linear acoustic model based on King's approximation.

  13. Estimating shallow water sound power levels and mitigation radii for the R/V Marcus G. Langseth using an 8 km long MCS streamer

    NASA Astrophysics Data System (ADS)

    Crone, Timothy J.; Tolstoy, Maya; Carton, Helene

    2014-10-01

    seismic surveys in shallow-water environments, the complexity of local geology and seafloor topography can make it difficult to accurately predict associated sound levels and establish appropriate mitigation radii required to ensure the safety of local marine protected species. This is primarily because necessary detailed information regarding the local seafloor topography and subseafloor geology is often unavailable before a survey begins. One potential solution to this problem is to measure received levels using the ship's multichannel seismic (MCS) streamer, which could allow for the dynamic real-time determination of sound levels and mitigation radii while a survey is underway. We analyze R/V Langseth streamer data collected on the shelf and slope near the Washington coast during the Cascadia Open-Access Seismic Transects (COAST) and Ridge2Trench projects to measure received levels up to a distance of approximately 8 km from the sound source array. We establish methods to filter, clean, and process streamer data to accurately determine received power levels and confidently establish mitigation radii. We show that in shallow water measured power levels can fluctuate due to the influence of seafloor topographic features, but that the use of the streamer for the establishment of dynamic mitigation radii is feasible and should be further pursued. The establishment of mitigation radii based on local conditions may help to maximize the safety of marine protected species while also maximizing the ability of researchers to conduct seismic studies.

  14. Erosion of carbon/carbon by solar wind charged particle radiation during a solar probe mission

    NASA Technical Reports Server (NTRS)

    Sokolowski, Witold; O'Donnell, Tim; Millard, Jerry

    1991-01-01

    The possible erosion of a carbon/carbon thermal shield by solar wind-charged particle radiation is reviewed. The present knowledge of erosion data for carbon and/or graphite is surveyed, and an explanation of erosion mechanisms under different charged particle environments is discussed. The highest erosion is expected at four solar radii. Erosion rates are analytically estimated under several conservative assumptions for a normal quiet and worst case solar wind storm conditions. Mass loss analyses and comparison studies surprisingly indicate that the predicted erosion rate by solar wind could be greater than by nominal free sublimation during solar wind storm conditions at four solar radii. The predicted overall mass loss of a carbon/carbon shield material during the critical four solar radii flyby can still meet the mass loss mission requirement of less than 0.0025 g/sec.

  15. Particle boundary structures at the magnetopause and the plasma sheet

    NASA Technical Reports Server (NTRS)

    Parks, G. K.; Lin, C. S.; Anderson, K. A.; Lin, R. P.; Reme, H.; Coroniti, F.; Meng, C.; Pellat, R.

    1979-01-01

    There are three classes of particle events in the vicinity of the magnetopause: a layer of particles right at the magnetopause which we identify with the boundary layer particles; spikes of particles just ahead of the magnetopause; and, sometimes, magnetosheath-like ions appearing inside the magnetosphere, the inclusion events. The energy spectra of these three classes of events are very similar, indicating a common particle source. The presence of a particle layer at the outer boundary of the plasma sheet is shown. This layer has typical dimensions of a few thousand km at 20 Earth radii. A typical velocity is a few tens of km/sec. These velocities and dimensions projected to ionospheric heights resemble those of visual auroras and suggest that aurorally associated particle phenomena are being detected.

  16. The velocity and energy profiles of elite cross-country skiers executing downhill turns with different radii.

    PubMed

    Sandbakk, Oyvind; Bucher Sandbakk, Silvana; Supej, Matej; Holmberg, Hans-Christer

    2014-01-01

    This study examined the influence of turn radius on velocity and energy profiles when skidding and step turning during more and less effective downhill turns while cross-country skiing. Thirteen elite female cross-country skiers performed single turns with a 9- or 12-m radius using the skidding technique and a 12- or 15-m radius with step turning. Mechanical parameters were monitored using a real-time kinematic Global Navigation Satellite System and video analysis. Step turning was more effective during all phases of a turn, leading to higher velocities than skidding (P < .05). With both techniques, a greater radius was associated with higher velocity (P < .05), but the quality of turning, as assessed on the basis of energy characteristics, was the same. More effective skidding turns involved more pronounced deceleration early in the turn and maintenance of higher velocity thereafter, while more effective step turning involved lower energy dissipation during the latter half of the turn. In conclusion, the single-turn analysis employed here reveals differences in the various techniques chosen by elite cross-country skiers when executing downhill turns of varying radii and can be used to assess the quality of such turns. PMID:24408350

  17. Tidal radii and destruction rates of globular clusters in the Milky Way due to bulge-bar and disk shocking

    SciTech Connect

    Moreno, Edmundo; Pichardo, Bárbara; Velázquez, Héctor

    2014-10-01

    We calculate orbits, tidal radii, and bulge-bar and disk shocking destruction rates for 63 globular clusters in our Galaxy. Orbits are integrated in both an axisymmetric and a nonaxisymmetric Galactic potential that includes a bar and a three-dimensional model for the spiral arms. With the use of a Monte Carlo scheme, we consider in our simulations observational uncertainties in the kinematical data of the clusters. In the analysis of destruction rates due to the bulge-bar, we consider the rigorous treatment of using the real Galactic cluster orbit instead of the usual linear trajectory employed in previous studies. We compare results in both treatments. We find that the theoretical tidal radius computed in the nonaxisymmetric Galactic potential compares better with the observed tidal radius than that obtained in the axisymmetric potential. In both Galactic potentials, bulge-shocking destruction rates computed with a linear trajectory of a cluster at its perigalacticons give a good approximation of the result obtained with the real trajectory of the cluster. Bulge-shocking destruction rates for clusters with perigalacticons in the inner Galactic region are smaller in the nonaxisymmetric potential than those in the axisymmetric potential. For the majority of clusters with high orbital eccentricities (e > 0.5), their total bulge+disk destruction rates are smaller in the nonaxisymmetric potential.

  18. Relativistic electrons and magnetic fields of the M87 jet on the ∼10 Schwarzschild radii scale

    SciTech Connect

    Kino, M.; Takahara, F.; Hada, K.; Doi, A.

    2014-05-01

    We explore energy densities of the magnetic fields and relativistic electrons in the M87 jet. Since the radio core at the jet base is identical to the optically thick surface against synchrotron self-absorption (SSA), the observing frequency is identical to the SSA turnover frequency. As a first step, we assume the radio core has a simple uniform sphere geometry. Using the observed angular size of the radio core measured by the Very Long Baseline Array at 43 GHz, we estimate the energy densities of magnetic fields (U{sub B} ) and relativistic electrons (U{sub e} ) on the basis of the standard SSA formula. Imposing the condition that the Poynting power and kinetic power of relativistic electrons should be smaller than the total power of the jet, we find that (1) the allowed range of the magnetic field strength (B {sub tot}) is 1 G ≤ B {sub tot} ≤ 15 G and that (2) 1 × 10{sup –5} ≤ U{sub e} /U{sub B} ≤ 6 × 10{sup 2} holds. The uncertainty of U{sub e} /U{sub B} comes from the strong dependence on the angular size of the radio core and the minimum Lorentz factor of non-thermal electrons (γ {sub e,min}) in the core. It is still unsettled whether resultant energetics are consistent with either the magnetohydrodynamic jet or the kinetic power dominated jet even on the ∼10 Schwarzschild radii scale.

  19. Tidal Radii and Destruction Rates of Globular Clusters in the Milky Way due to Bulge-Bar and Disk Shocking

    NASA Astrophysics Data System (ADS)

    Moreno, Edmundo; Pichardo, Bárbara; Velázquez, Héctor

    2014-10-01

    We calculate orbits, tidal radii, and bulge-bar and disk shocking destruction rates for 63 globular clusters in our Galaxy. Orbits are integrated in both an axisymmetric and a nonaxisymmetric Galactic potential that includes a bar and a three-dimensional model for the spiral arms. With the use of a Monte Carlo scheme, we consider in our simulations observational uncertainties in the kinematical data of the clusters. In the analysis of destruction rates due to the bulge-bar, we consider the rigorous treatment of using the real Galactic cluster orbit instead of the usual linear trajectory employed in previous studies. We compare results in both treatments. We find that the theoretical tidal radius computed in the nonaxisymmetric Galactic potential compares better with the observed tidal radius than that obtained in the axisymmetric potential. In both Galactic potentials, bulge-shocking destruction rates computed with a linear trajectory of a cluster at its perigalacticons give a good approximation of the result obtained with the real trajectory of the cluster. Bulge-shocking destruction rates for clusters with perigalacticons in the inner Galactic region are smaller in the nonaxisymmetric potential than those in the axisymmetric potential. For the majority of clusters with high orbital eccentricities (e > 0.5), their total bulge+disk destruction rates are smaller in the nonaxisymmetric potential.

  20. Computation of the atomic radii through the conjoint action of the effective nuclear charge and the ionization energy

    NASA Astrophysics Data System (ADS)

    Chakraborty, Tanmoy; Gazi, Kamarujjaman; Ghosh, Dulal C.

    2010-08-01

    A new ansatz for computing the absolute radii (r) of the atoms based upon the conjoint action of two periodic properties namely, ionization energy (I) and effective nuclear charge (Zeff ) is proposed as r = a(1/I) + b(1/Zeff ) + c, where a, b and c are constants, determined by regression analysis. The ansatz is invoked to calculate sizes of atoms of 103 elements of the periodic table. In the absence of any benchmark to perform a validity test of any set of atomic size, reliance is upon the 'sine qua non' of a set of atomic size. The express periodicity of periods and groups exhibited by the computed size data, d and f block contraction and the manifest relativistic effect in the sizes of lanthanoids and actinoids, etc. speak volumes for the efficacy of the present method. Furthermore, size data have been linked to compute some physical descriptors of the real world, such as equilibrium internuclear distances of a good number of heteronuclear diatomic molecules as validity test. A comparative study of the theoretical vis-à-vis experimental equilibrium inter-nuclear distances reveals that there is close agreement between the theoretical prediction and experimental determination.

  1. Understanding the Effects of Stellar Multiplicity on the Derived Planet Radii from Transit Surveys: Implications for Kepler, K2, and TESS

    NASA Astrophysics Data System (ADS)

    Ciardi, David R.; Beichman, Charles A.; Horch, Elliott P.; Howell, Steve B.

    2015-05-01

    We present a study on the effect of undetected stellar companions on the derived planetary radii for Kepler Objects of Interest (KOIs). The current production of the KOI list assumes that each KOI is a single star. Not accounting for stellar multiplicity statistically biases the planets toward smaller radii. The bias toward smaller radii depends on the properties of the companion stars and whether the planets orbit the primary or the companion stars. Defining a planetary radius correction factor, XR, we find that if the KOIs are assumed to be single, then, on average, the planetary radii may be underestimated by a factor of < {{X}R}> ≈ 1.5. If typical radial velocity and high-resolution imaging observations are performed and no companions are detected, then this factor reduces to < {{X}R}> ≈ 1.2. The correction factor < {{X}R}> is dependent on the primary star properties and ranges from < {{X}R}> ≈ 1.6 for A and F stars to < {{X}R}> ≈ 1.2 for K and M stars. For missions like K2 and TESS where the stars may be closer than the stars in the Kepler target sample, observational vetting (primary imaging) reduces the radius correction factor to < {{X}R}> ≈ 1.1. Finally, we show that if the stellar multiplicity rates are not accounted for correctly, then occurrence rate calculations for Earth-sized planets may overestimate the frequency of small planets by as much as 15%–20%.

  2. Interferometry radii in heavy-ion collisions at {radical}(s)=200 GeV and 2.76 TeV

    SciTech Connect

    Bozek, Piotr

    2011-04-15

    The expansion of the fireball created in Au-Au collisions at {radical}(s)=200 GeV and Pb-Pb collisions at 2.76 TeV is modelled using relativistic viscous hydrodynamics. The experimentally observed interferometry radii are well reproduced. Additional pre-equilibrium flow slightly improves the results for the lower energies studied.

  3. Particle separation

    DOEpatents

    Moosmuller, Hans; Chakrabarty, Rajan K.; Arnott, W. Patrick

    2011-04-26

    Embodiments of a method for selecting particles, such as based on their morphology, is disclosed. In a particular example, the particles are charged and acquire different amounts of charge, or have different charge distributions, based on their morphology. The particles are then sorted based on their flow properties. In a specific example, the particles are sorted using a differential mobility analyzer, which sorts particles, at least in part, based on their electrical mobility. Given a population of particles with similar electrical mobilities, the disclosed process can be used to sort particles based on the net charge carried by the particle, and thus, given the relationship between charge and morphology, separate the particles based on their morphology.

  4. Particle separation

    NASA Technical Reports Server (NTRS)

    Moosmuller, Hans (Inventor); Chakrabarty, Rajan K. (Inventor); Arnott, W. Patrick (Inventor)

    2011-01-01

    Embodiments of a method for selecting particles, such as based on their morphology, is disclosed. In a particular example, the particles are charged and acquire different amounts of charge, or have different charge distributions, based on their morphology. The particles are then sorted based on their flow properties. In a specific example, the particles are sorted using a differential mobility analyzer, which sorts particles, at least in part, based on their electrical mobility. Given a population of particles with similar electrical mobilities, the disclosed process can be used to sort particles based on the net charge carried by the particle, and thus, given the relationship between charge and morphology, separate the particles based on their morphology.

  5. Analysis of optical trapping and propulsion of Rayleigh particles using Airy beam.

    PubMed

    Cheng, Hua; Zang, Weiping; Zhou, Wenyuan; Tian, Jianguo

    2010-09-13

    The radiation forces and trajectories of Rayleigh dielectric particles induced by one-dimensional Airy beam were numerically analyzed. Results show that the Airy beam drags particles into the optical intensity peaks, and guides particles vertically along parabolic trajectories. Viscosity of surrounding medium significantly affects the trajectories. Random Brownian force affects the trajectories. Meanwhile, trapping potential depths and minimum trapping particle radii in different potential wells were also discussed. The trapping stability could be improved by increasing either the input peak intensity or the particle radius. PMID:20940930

  6. Slip flow through colloidal crystals of varying particle diameter.

    PubMed

    Rogers, Benjamin J; Wirth, Mary J

    2013-01-22

    Slip flow of water through silica colloidal crystals was investigated experimentally for eight different particle diameters, which have hydraulic channel radii ranging from 15 to 800 nm. The particle surfaces were silylated to be low in energy, with a water contact angle of 83°, as determined for a silylated flat surface. Flow rates through centimeter lengths of colloidal crystal were measured using a commercial liquid chromatograph for accurate comparisons of water and toluene flow rates using pressure gradients as high as 10(10) Pa/m. Toluene exhibited no-slip Hagen-Poiseuille flow for all hydraulic channel radii. For water, the slip flow enhancement as a function of hydraulic channel radius was described well by the expected slip flow correction for Hagen-Poiseuille flow, and the data revealed a constant slip length of 63 ± 3 nm. A flow enhancement of 20 ± 2 was observed for the smallest hydraulic channel radius of 15 nm. The amount of slip flow was found to be independent of shear rate over a range of fluid velocities from 0.7 to 5.8 mm/s. The results support the applicability of the slip flow correction for channel radii as small as 15 nm. The work demonstrates that packed beds of submicrometer particles enable slip flow to be employed for high-volume flow rates. PMID:23237590

  7. Slip Flow through Colloidal Crystals of Varying Particle Diameter

    PubMed Central

    Rogers, Benjamin J.; Wirth, Mary J.

    2012-01-01

    Slip flow of water through silica colloidal crystals was investigated experimentally for 8 different particle diameters, which have hydraulic channel radii ranging from 15 nm to 800 nm. The particle surfaces were silylated to be low in energy, with a water contact angle of 83°, as determined for a silylated flat surface. Flow rates through centimeter lengths of colloidal crystal were measured using a commercial liquid chromatograph for accurate comparisons of water and toluene flow rates using pressure gradients as high as 1010 Pa/m. Toluene exhibited no-slip Hagen-Poiseuille flow for all hydraulic channel radii. For water, the slip flow enhancement as a function of hydraulic channel radius was described well by the expected slip flow correction for Hagen-Poiseuille flow, and the data revealed a constant slip length of 63±3 nm. A flow enhancement of 20±2 was observed for the smallest hydraulic channel radius of 15 nm. The amount of slip flow was found to be independent of shear rate over a range of fluid velocities from 0.7 to 5.8 mm/s. The results support the applicability of the slip flow correction for channel radii as small as 15 nm. The work demonstrates that packed beds of submicrometer particles enable slip flow to be employed for high volume flow rates. PMID:23237590

  8. Particles Growing in Solutions: Depletion Forces and Instability of Homogeneous Particle Distribution

    NASA Technical Reports Server (NTRS)

    Chernov, A. A.

    2004-01-01

    Crystallites, droplets and amorphous precipitates growing from supersaturated solution are surrounded by zones, which are depleted with respect to the molecules they are built of. If two such particles of colloidal size are separated by a distance comparable to their diameters, then the depletion within the gap between particles is deeper than that at the outer portion of the particles. This will cause depletion attraction between the particles should appear. It may cause particle coagulation and decay of the originally homogeneous particle distribution into a system of clouds within which the particle number density is higher, separated by the region of the lower number density. Stability criterion, Q = 4 pi R(exp 3)c/3 >> 1, was analytically found along with typical particle density distribution wavevector q = (Q/I)(exp 1/2)(a/R)(exp 1/4). Here, R and a are the particle and molecular radii, respectively, c is the average molecular number density in solution and I is the squared diffusion length covered by a molecule during a typical time characterizing decay of molecular concentration in solution due to consumption of the molecules by the growing particles.

  9. Kramers escape of a self-propelled particle

    NASA Astrophysics Data System (ADS)

    Geiseler, Alexander; Hänggi, Peter; Schmid, Gerhard

    2016-08-01

    We investigate the escape rate of an overdamped, self-propelled spherical Brownian particle on a surface from a metastable potential well. Within a modeling in terms of a 1D constant speed of the particle's active dynamics we consider the associated rate using both numerical and analytical approaches. Regarding the properties of the stationary state in the potential well, two major timescales exist, each governing the translational and the rotational dynamics of the particle, respectively. The particle radius is identified to present the essential quantity in charge of regulating the ratio between those timescales. For very small and very large particle radii, approximate analytic expressions for the particle's escape rate can be derived, which, within their respective range of validity, compare favorably with the precise escape numerics of the underlying full two-dimensional Fokker-Planck description.

  10. The SLUGGS Survey: stellar kinematics, kinemetry and trends at large radii in 25 early-type galaxies

    NASA Astrophysics Data System (ADS)

    Foster, Caroline; Pastorello, Nicola; Roediger, Joel; Brodie, Jean P.; Forbes, Duncan A.; Kartha, Sreeja S.; Pota, Vincenzo; Romanowsky, Aaron J.; Spitler, Lee R.; Strader, Jay; Usher, Christopher; Arnold, Jacob A.

    2016-03-01

    Due to longer dynamical time-scales, the outskirts of early-type galaxies retain the footprint of their formation and assembly. Under the popular two-phase galaxy formation scenario, an initial in situ phase of star formation is followed by minor merging and accretion of ex situ stars leading to the expectation of observable transitions in the kinematics and stellar populations on large scales. However, observing the faint galactic outskirts is challenging, often leaving the transition unexplored. The large-scale, spatially resolved stellar kinematic data from the SAGES Legacy Unifying Galaxies and GlobularS (SLUGGS) survey are ideal for detecting kinematic transitions. We present kinematic maps out to 2.6 effective radii on average, kinemetry profiles, measurement of kinematic twists and misalignments, and the average outer intrinsic shape of 25 SLUGGS galaxies. We find good overall agreement in the kinematic maps and kinemetry radial profiles with literature. We are able to confirm significant radial modulations in rotational versus pressure support of galaxies with radius so that the central and outer rotational properties may be quite different. We also test the suggestion that galaxies may be more triaxial in their outskirts and find that while fast rotating galaxies were already shown to be axisymmetric in their inner regions, we are unable to rule out triaxiality in their outskirts. We compare our derived outer kinematic information to model predictions from a two-phase galaxy formation scenario. We find that the theoretical range of local outer angular momentum agrees well with our observations, but that radial modulations are much smaller than predicted.

  11. The SLUGGS survey: the mass distribution in early-type galaxies within five effective radii and beyond

    NASA Astrophysics Data System (ADS)

    Alabi, Adebusola B.; Forbes, Duncan A.; Romanowsky, Aaron J.; Brodie, Jean P.; Strader, Jay; Janz, Joachim; Pota, Vincenzo; Pastorello, Nicola; Usher, Christopher; Spitler, Lee R.; Foster, Caroline; Jennings, Zachary G.; Villaume, Alexa; Kartha, Sreeja

    2016-08-01

    We study mass distributions within and beyond 5~effective radii ($R_{\\rm e}$) in 23 early-type galaxies from the SLUGGS survey, using their globular cluster (GC) kinematic data. The data are obtained with Keck/DEIMOS spectrograph, and consist of line-of-sight velocities for ~$3500$ GCs, measured with a high precision of ~15 $\\rm km\\ s^{-1}$ per GC and extending out to $~13 R_{\\rm e}$. We obtain the mass distribution in each galaxy using the tracer mass estimator of Watkins et al. and account for kinematic substructures, rotation of the GC systems and galaxy flattening in our mass estimates. The observed scatter between our mass estimates and results from the literature is less than 0.2 dex. The dark matter fraction within $5R_{\\rm e}$ ($f_{\\rm DM}$) increases from ~$0.6$ to ~$0.8$ for low- and high-mass galaxies, respectively, with some intermediate-mass galaxies ($M_*{\\sim}10^{11}M_\\odot$) having low $f_{\\rm DM}\\sim0.3$, which appears at odds with predictions from simple galaxy models. We show that these results are independent of the adopted orbital anisotropy, stellar mass-to-light ratio, and the assumed slope of the gravitational potential. However, the low $f_{\\rm DM}$ in the ~$10^{11}M_\\odot$ galaxies agrees with the cosmological simulations of Wu et al. where the pristine dark matter distribution has been modified by baryons during the galaxy assembly process. We find hints that these $M_*\\sim10^{11}M_\\odot$ galaxies with low $f_{\\rm DM}$ have very diffuse dark matter haloes, implying that they assembled late. Beyond $5R_{\\rm e}$, the $M/L$ gradients are steeper in the more massive galaxies and shallower in both low and intermediate mass galaxies.

  12. Magnetohydrodynamic Numerical Simulation of Wind Production from Hot Accretion Flows around Black Holes at Very Large Radii

    NASA Astrophysics Data System (ADS)

    Bu, De-Fu; Yuan, Feng; Gan, Zhao-Ming; Yang, Xiao-Hong

    2016-06-01

    Numerical simulations of hot accretion flows around black holes have shown the existence of strong wind. Those works focused only on the region close to the black hole and thus it is unknown whether or where the wind production stops at large radii. To address this question, we have recently performed hydrodynamic (HD) simulations by taking into account the gravitational potential of both the black hole and the nuclear star cluster. The latter is assumed to be proportional to {σ }2{ln}(r), with σ being the velocity dispersion of stars and r the distance from the center of the galaxy. It was found that when the gravity is dominated by nuclear stars, i.e., outside a radius {R}A\\equiv {{GM}}{{BH}}/{σ }2, winds can no longer be produced. That work, however, neglects the magnetic field, which is believed to play a crucial dynamical role in the accretion and thus must be taken into account. In this paper, we revisit this problem by performing magnetohydrodynamic (MHD) simulations. We confirm the result of our previous paper, namely that wind cannot be produced in the region R\\gt {R}A. Our result, combined with recent results of Yuan et al., indicates that the formula describing the mass flux of wind, {\\dot{M}}{{wind}}={\\dot{M}}{{BH}}(r/20{r}s), can only be applied to the region where the black hole potential is dominant. Here {\\dot{M}}{{BH}} is the mass accretion rate at the black hole horizon and the value of R A is similar to the Bondi radius.

  13. The SLUGGS survey: the mass distribution in early-type galaxies within five effective radii and beyond

    NASA Astrophysics Data System (ADS)

    Alabi, Adebusola B.; Forbes, Duncan A.; Romanowsky, Aaron J.; Brodie, Jean P.; Strader, Jay; Janz, Joachim; Pota, Vincenzo; Pastorello, Nicola; Usher, Christopher; Spitler, Lee R.; Foster, Caroline; Jennings, Zachary G.; Villaume, Alexa; Kartha, Sreeja

    2016-08-01

    We study mass distributions within and beyond 5 effective radii (Re) in 23 early-type galaxies from the SAGES Legacy Unifying Globulars and Galaxies Survey, using their globular cluster (GC) kinematic data. The data are obtained with Keck/DEep Imaging Multi-Object Spectrograph, and consist of line-of-sight velocities for ˜3500 GCs, measured with a high precision of ˜15 km s-1 per GC and extending out to ˜13 Re. We obtain the mass distribution in each galaxy using the tracer mass estimator of Watkins et al. and account for kinematic substructures, rotation of the GC systems and galaxy flattening in our mass estimates. The observed scatter between our mass estimates and results from the literature is less than 0.2 dex. The dark matter fraction within 5 Re (fDM) increases from ˜0.6 to ˜0.8 for low- and high-mass galaxies, respectively, with some intermediate-mass galaxies (M* ˜ 1011 M⊙) having low fDM ˜ 0.3, which appears at odds with predictions from simple galaxy models. We show that these results are independent of the adopted orbital anisotropy, stellar mass-to-light (M/L) ratio, and the assumed slope of the gravitational potential. However, the low fDM in the ˜1011 M⊙ galaxies agrees with the cosmological simulations of Wu et al. where the pristine dark matter distribution has been modified by baryons during the galaxy assembly process. We find hints that these M* ˜ 1011 M⊙ galaxies with low fDM have very diffuse dark matter haloes, implying that they assembled late. Beyond 5 Re, the M/L gradients are steeper in the more massive galaxies and shallower in both low and intermediate mass galaxies.

  14. Particle generator

    DOEpatents

    Hess, Wayne P.; Joly, Alan G.; Gerrity, Daniel P.; Beck, Kenneth M.; Sushko, Peter V.; Shlyuger, Alexander L.

    2005-06-28

    Energy tunable solid state sources of neutral particles are described. In a disclosed embodiment, a halogen particle source includes a solid halide sample, a photon source positioned to deliver photons to a surface of the halide, and a collimating means positioned to accept a spatially defined plume of hyperthermal halogen particles emitted from the sample surface.

  15. Alpha Particle

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    Term that is sometimes used to describe a helium nucleus, a positively charged particle that consists of two protons and two neutrons, bound together. Alpha particles, which were discovered by Ernest Rutherford (1871-1937) in 1898, are emitted by atomic nuclei that are undergoing alpha radioactivity. During this process, an unstable heavy nucleus spontaneously emits an alpha particle and transmut...

  16. Particle Detectors

    NASA Astrophysics Data System (ADS)

    Grupen, Claus; Shwartz, Boris

    2011-09-01

    Preface to the first edition; Preface to the second edition; Introduction; 1. Interactions of particles and radiation with matter; 2. Characteristic properties of detectors; 3. Units of radiation measurements and radiation sources; 4. Accelerators; 5. Main physical phenomena used for particle detection and basic counter types; 6. Historical track detectors; 7. Track detectors; 8. Calorimetry; 9. Particle identification; 10. Neutrino detectors; 11. Momentum measurement and muon detection; 12. Ageing and radiation effects; 13. Example of a general-purpose detector: Belle; 14. Electronics; 15. Data analysis; 16. Applications of particle detectors outside particle physics; 17. Glossary; 18. Solutions; 19. Resumé; Appendixes; Index.

  17. Small particles dominate Saturn's Phoebe ring to surprisingly large distances.

    PubMed

    Hamilton, Douglas P; Skrutskie, Michael F; Verbiscer, Anne J; Masci, Frank J

    2015-06-11

    Saturn's faint outermost ring, discovered in 2009 (ref. 1), is probably formed by particles ejected from the distant moon Phoebe. The ring was detected between distances of 128 and 207 Saturn radii (RS = 60,330 kilometres) from the planet, with a full vertical extent of 40RS, making it well over ten times larger than Saturn's hitherto largest known ring, the E ring. The total radial extent of the Phoebe ring could not, however, be determined at that time, nor could particle sizes be significantly constrained. Here we report infrared imaging of the entire ring, which extends from 100RS out to a surprisingly distant 270RS. We model the orbital dynamics of ring particles launched from Phoebe, and construct theoretical power-law profiles of the particle size distribution. We find that very steep profiles fit the data best, and that elevated grain temperatures, arising because of the radiative inefficiency of the smallest grains, probably contribute to the steepness. By converting our constraint on particle sizes into a form that is independent of the uncertain size distribution, we determine that particles with radii greater than ten centimetres, whose orbits do not decay appreciably inward over 4.5 billion years, contribute at most about ten per cent to the cross-sectional area of the ring's dusty component. PMID:26062508

  18. Small particles dominate Saturn's Phoebe ring to surprisingly large distances

    NASA Astrophysics Data System (ADS)

    Hamilton, Douglas P.; Skrutskie, Michael F.; Verbiscer, Anne J.; Masci, Frank J.

    2015-06-01

    Saturn's faint outermost ring, discovered in 2009 (ref. 1), is probably formed by particles ejected from the distant moon Phoebe. The ring was detected between distances of 128 and 207 Saturn radii (RS = 60,330 kilometres) from the planet, with a full vertical extent of 40RS, making it well over ten times larger than Saturn's hitherto largest known ring, the E ring. The total radial extent of the Phoebe ring could not, however, be determined at that time, nor could particle sizes be significantly constrained. Here we report infrared imaging of the entire ring, which extends from 100RS out to a surprisingly distant 270RS. We model the orbital dynamics of ring particles launched from Phoebe, and construct theoretical power-law profiles of the particle size distribution. We find that very steep profiles fit the data best, and that elevated grain temperatures, arising because of the radiative inefficiency of the smallest grains, probably contribute to the steepness. By converting our constraint on particle sizes into a form that is independent of the uncertain size distribution, we determine that particles with radii greater than ten centimetres, whose orbits do not decay appreciably inward over 4.5 billion years, contribute at most about ten per cent to the cross-sectional area of the ring's dusty component.

  19. E2 strengths and transition radii difference of one-phonon 2+ states of 92Zr from electron scattering at low momentum transfer

    NASA Astrophysics Data System (ADS)

    Obeid, A. Scheikh; Burda, O.; Chernykh, M.; Krugmann, A.; von Neumann-Cosel, P.; Pietralla, N.; Poltoratska, I.; Ponomarev, V. Yu.; Walz, C.

    2013-01-01

    Background: Mixed-symmetry 2+ states in vibrational nuclei are characterized by a sign change between dominant proton and neutron valence-shell components with respect to the fully symmetric 2+ state. The sign can be measured by a decomposition of proton and neutron transition radii with a combination of inelastic electron and hadron scattering [C. Walz , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.106.062501 106, 062501 (2011)]. For the case of 92Zr, a difference could be experimentally established for the neutron components, while about equal proton transition radii were indicated by the data.Purpose: Determination of the ground-state (g.s.) transition strength of the mixed-symmetry 22+ state and verification of the expected vanishing of the proton transition radii difference between the one-phonon 2+ states in 92Zr.Method: Differential cross sections for the excitation of one-phonon 2+ and 3- states in 92Zr have been measured with the (e,e') reaction at the S-DALINAC in a momentum transfer range q≃0.3-0.6 fm-1.Results: Transition strengths B(E2;21+→01+)=6.18(23), B(E2;22+→01+)=3.31(10), and B(E3;31-→01+)=18.4(1.1) Weisskopf units are determined from a comparison of the experimental cross sections to quasiparticle-phonon model (QPM) calculations. It is shown that a model-independent plane wave Born approximation (PWBA) analysis can fix the ratio of B(E2) transition strengths to the 21,2+ states with a precision of about 1%. The method furthermore allows to extract their proton transition radii difference. With the present data ΔR=-0.12(51) fm is obtained.Conclusions: Electron scattering at low momentum transfers can provide information on transition radii differences of one-phonon 2+ states even in heavy nuclei. Proton transition radii for the 21,2+ states in 92Zr are found to be identical within uncertainties. The g.s. transition probability for the mixed-symmetry state can be determined with high precision limited only by the available

  20. A revised set of values of single-bond radii derived from the observed interatomic distances in metals by correction for bond number and resonance energy

    PubMed Central

    Pauling, Linus; Kamb, Barclay

    1986-01-01

    An earlier discussion [Pauling, L. (1947) J. Am. Chem. Soc. 69, 542] of observed bond lengths in elemental metals with correction for bond number and resonance energy led to a set of single-bond metallic radii with values usually somewhat less than the corresponding values obtained from molecules and complex ions. A theory of resonating covalent bonds has now been developed that permits calculation of the number of resonance structures per atom and of the effective resonance energy per bond. With this refined method of correcting the observed bond lengths for the effect of resonance energy, a new set of single-bond covalent radii, in better agreement with values from molecules and complex ions, has been constructed. PMID:16593698

  1. A COMPARISON BETWEEN THE HALF-LIGHT RADII, LUMINOSITIES, AND UBV COLORS OF GLOBULAR CLUSTERS IN M31 AND THE GALAXY

    SciTech Connect

    Van den Bergh, Sidney

    2010-10-15

    The Milky Way system and the Andromeda galaxy experienced radically different evolutionary histories. Nevertheless, it is found that these two galaxies ended up with globular cluster systems in which individual clusters have indistinguishable distributions of half-light radii. Furthermore, globulars in both M31 and the Galaxy are found to have radii that are independent of their luminosities. In this respect, globular clusters differ drastically from early-type galaxies in which half-light radius and luminosity are tightly correlated. Metal-rich globular clusters in M31 occupy a slightly larger volume than do those in the Galaxy. The specific globular cluster frequency in the Andromeda galaxy is found to be significantly higher than it is in the Milky Way system. The present discussion is based on the 107 Galactic globular clusters, and 200 putative globulars in M31, for which UBV photometry was available.

  2. In-gas-cell laser ionization spectroscopy in the vicinity of 100Sn: Magnetic moments and mean-square charge radii of N=50-54 Ag

    NASA Astrophysics Data System (ADS)

    Ferrer, R.; Bree, N.; Cocolios, T. E.; Darby, I. G.; De Witte, H.; Dexters, W.; Diriken, J.; Elseviers, J.; Franchoo, S.; Huyse, M.; Kesteloot, N.; Kudryavtsev, Yu.; Pauwels, D.; Radulov, D.; Roger, T.; Savajols, H.; Van Duppen, P.; Venhart, M.

    2014-01-01

    In-gas-cell laser ionization spectroscopy studies on the neutron deficient 97-101Ag isotopes have been performed with the LISOL setup. Magnetic dipole moments and mean-square charge radii have been determined for the first time with the exception of 101Ag, which was found in good agreement with previous experimental values. The reported results allow tentatively assigning the spin of 97,99Ag to 9/2 and confirming the presence of an isomeric state in these two isotopes, whose collapsed hyperfine structure suggests a spin of 1/2 >. The effect of the N=50 shell closure is not only manifested in the magnetic moments but also in the evolution of the mean-square charge radii of the isotopes investigated, in accordance with the spherical droplet model predictions.

  3. The vertical distribution of Martian aerosol particle size

    NASA Astrophysics Data System (ADS)

    Guzewich, Scott D.; Smith, Michael D.; Wolff, Michael J.

    2014-12-01

    Using approximately 410 limb-viewing observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), we retrieve the vertical distribution of Martian dust and water ice aerosol particle sizes. We find that dust particles have an effective radius of 1.0 µm over much of the atmospheric column below 40 km throughout the Martian year. This includes the detached tropical dust layers detected in previous studies. Little to no variation with height is seen in dust particle size. Water ice clouds within the aphelion cloud belt exhibit a strong sorting of particle size with height, however, and the effective radii range from >3 µm below 20 km to near 1.0 µm at 40 km altitude. Conversely, water ice clouds in the seasonal polar hoods show a near-uniform particle size with an effective radius of approximately 1.5 µm throughout the atmospheric column.

  4. Determination of time zero from a charged particle detector

    DOEpatents

    Green, Jesse Andrew

    2011-03-15

    A method, system and computer program is used to determine a linear track having a good fit to a most likely or expected path of charged particle passing through a charged particle detector having a plurality of drift cells. Hit signals from the charged particle detector are associated with a particular charged particle track. An initial estimate of time zero is made from these hit signals and linear tracks are then fit to drift radii for each particular time-zero estimate. The linear track having the best fit is then searched and selected and errors in fit and tracking parameters computed. The use of large and expensive fast detectors needed to time zero in the charged particle detectors can be avoided by adopting this method and system.

  5. Particle astrophysics

    NASA Technical Reports Server (NTRS)

    Sadoulet, Bernard; Cronin, James; Aprile, Elena; Barish, Barry C.; Beier, Eugene W.; Brandenberger, Robert; Cabrera, Blas; Caldwell, David; Cassiday, George; Cline, David B.

    1991-01-01

    The following scientific areas are reviewed: (1) cosmology and particle physics (particle physics and the early universe, dark matter, and other relics); (2) stellar physics and particles (solar neutrinos, supernovae, and unconventional particle physics); (3) high energy gamma ray and neutrino astronomy; (4) cosmic rays (space and ground observations). Highest scientific priorities for the next decade include implementation of the current program, new initiatives, and longer-term programs. Essential technological developments, such as cryogenic detectors of particles, new solar neutrino techniques, and new extensive air shower detectors, are discussed. Also a certain number of institutional issues (the funding of particle astrophysics, recommended funding mechanisms, recommended facilities, international collaborations, and education and technology) which will become critical in the coming decade are presented.

  6. Particle therapy

    SciTech Connect

    Raju, M.R.

    1993-09-01

    Particle therapy has a long history. The experimentation with particles for their therapeutic application got started soon after they were produced in the laboratory. Physicists played a major role in proposing the potential applications in radiotherapy as well as in the development of particle therapy. A brief review of the current status of particle radiotherapy with some historical perspective is presented and specific contributions made by physicists will be pointed out wherever appropriate. The rationale of using particles in cancer treatment is to reduce the treatment volume to the target volume by using precise dose distributions in three dimensions by using particles such as protons and to improve the differential effects on tumors compared to normal tissues by using high-LET radiations such as neutrons. Pions and heavy ions combine the above two characteristics.

  7. Particle astrophysics

    NASA Astrophysics Data System (ADS)

    Sadoulet, Bernard; Cronin, James; Aprile, Elena; Barish, Barry C.; Beier, Eugene W.; Brandenberger, Robert; Cabrera, Blas; Caldwell, David; Cassiday, George; Cline, David B.

    The following scientific areas are reviewed: (1) cosmology and particle physics (particle physics and the early universe, dark matter, and other relics); (2) stellar physics and particles (solar neutrinos, supernovae, and unconventional particle physics); (3) high energy gamma ray and neutrino astronomy; (4) cosmic rays (space and ground observations). Highest scientific priorities for the next decade include implementation of the current program, new initiatives, and longer-term programs. Essential technological developments, such as cryogenic detectors of particles, new solar neutrino techniques, and new extensive air shower detectors, are discussed. Also a certain number of institutional issues (the funding of particle astrophysics, recommended funding mechanisms, recommended facilities, international collaborations, and education and technology) which will become critical in the coming decade are presented.

  8. Reaction cross-sections and reduced strong absorption radii of nuclei in the vicinity of closed shells N = 20 and N = 28

    NASA Astrophysics Data System (ADS)

    Khouaja, A.; Villari, A. C. C.; Benjelloun, M.; Auger, G.; Baiborodin, D.; Catford, W.; Chartier, M.; Demonchy, C. E.; Dlouhy, Z.; Gillibert, A.; Giot, L.; Hirata, D.; Lépine-Szily, A.; Mittig, W.; Orr, N.; Penionzhkevich, Y.; Pitae, S.; Roussel-Chomaz, P.; Saint-Laurent, M. G.; Savajols, H.

    2005-09-01

    Energy integrated reaction cross-section measurements of around sixty neutron-rich nuclei covering the region of closed shells N = 20 and N = 28 were performed at intermediate energy (30-65 A . MeV) using direct method. In this experiment, silicon detectors were used as active targets. The reduced strong absorption radii, r02, for 19 new nuclei (27F, 27,30Ne, 33Na, 28, 34-35Mg, 36-38Al, 38-40Si, 41-42P, 42-44S and 45Cl) are deduced for the first time. An additional 60 radii, also measured in this experiment, are compared to results from literature. A new quadratic parametrization is proposed for the nuclear radius as a function of the isospin in the region of closed shells N = 8 and N = 28. According to this parametrization, the skin effect is well reproduced and anomalous behaviour on the radii are observed in 23N, 29Ne, 33Na, 35Mg, 44S, 45Cl and 45Ar nuclei.

  9. CHARACTERIZING THE COOL KEPLER OBJECTS OF INTERESTS. NEW EFFECTIVE TEMPERATURES, METALLICITIES, MASSES, AND RADII OF LOW-MASS KEPLER PLANET-CANDIDATE HOST STARS

    SciTech Connect

    Muirhead, Philip S.; Hamren, Katherine; Schlawin, Everett; Lloyd, James P.; Rojas-Ayala, Barbara; Covey, Kevin R.

    2012-05-10

    We report stellar parameters for late-K and M-type planet-candidate host stars announced by the Kepler Mission. We obtained medium-resolution, K-band spectra of 84 cool (T{sub eff} {approx}< 4400 K) Kepler Objects of Interest (KOIs) from Borucki et al. We identified one object as a giant (KOI 977); for the remaining dwarfs, we measured effective temperatures (T{sub eff}) and metallicities [M/H] using the K-band spectral indices of Rojas-Ayala et al. We determine the masses (M{sub *}) and radii (R{sub *}) of the cool KOIs by interpolation onto the Dartmouth evolutionary isochrones. The resultant stellar radii are significantly less than the values reported in the Kepler Input Catalog and, by construction, correlate better with T{sub eff}. Applying the published KOI transit parameters to our stellar radius measurements, we report new physical radii for the planet candidates. Recalculating the equilibrium temperatures of the planet-candidates assuming Earth's albedo and re-radiation fraction, we find that three of the planet-candidates are terrestrial sized with orbital semimajor axes that lie within the habitable zones of their host stars (KOI 463.01, KOI 812.03, and KOI 854.01). The stellar parameters presented in this Letter serve as a resource for prioritization of future follow-up efforts to validate and characterize the cool KOI planet candidates.

  10. Effect of collisions on dust particle charging via particle-in-cell Monte-Carlo collision

    SciTech Connect

    Rovagnati, B.; Davoudabadi, M.; Lapenta, G.; Mashayek, F.

    2007-10-01

    In this paper, the effect of collisions on the charging and shielding of a single dust particle immersed in an infinite plasma is studied. A Monte-Carlo collision (MCC) algorithm is implemented in the particle-in-cell DEMOCRITUS code to account for the collisional phenomena which are typical of dusty plasmas in plasma processing, namely, electron-neutral elastic scattering, ion-neutral elastic scattering, and ion-neutral charge exchange. Both small and large dust particle radii, as compared to the characteristic Debye lengths, are considered. The trends of the steady-state dust particle potential at increasing collisionality are presented and discussed. The ions and electron energy distributions at various locations and at increasing collisionality in the case of large particle radius are shown and compared to their local Maxwellians. The ion-neutral charge-exchange collision is found to be by far the most important collisional phenomenon. For small particle radius, collisional effects are found to be important also at low level of collisionality, as more ions are collected by the dust particle due to the destruction of trapped ion orbits. For large particle radius, the major collisional effect is observed to take place in proximity of the presheath. Finally, the species energy distribution functions are found to approach their local Maxwellians at increasing collisionality.

  11. Virtual Energetic Particle Observatory (VEPO)

    NASA Technical Reports Server (NTRS)

    Cooper, John F.; Lal, Nand; McGuire, Robert E.; Szabo, Adam; Narock, Thomas W.; Armstrong, Thomas P.; Manweiler, Jerry W.; Patterson, J. Douglas; Hill, Matthew E.; Vandergriff, Jon D.; McKibben, Robert B.; Lopate, Clifford; Tranquille, Cecil

    2008-01-01

    The Virtual Energetic Particle Observatory (VEPO) focuses on improved discovery, access, and usability of heliospheric energetic particle and ancillary data products from selected spacecraft and sub-orbital instruments of the heliophysics data environment. The energy range of interest extends over the full range of particle acceleration from keV energies of suprathermal seed particles to GeV energies of galactic cosmic ray particles. Present spatial coverage is for operational and legacy spacecraft operating from the inner to the outer heliosphere, e.g. from measurements by the two Helios spacecraft to 0.3 AU to the inner heliosheath region now being traversed by the two Voyager spacecraft. This coverage will eventually be extended inward to ten solar radii by the planned NASA solar probe mission and at the same time beyond the heliopause into the outer heliosheath by continued Voyager operations. The geospace fleet of spacecraft providing near-Earth interplanetary measurements, selected magnetospheric spacecraft providing direct measurements of penetrating interplanetary energetic particles, and interplanetary cruise measurements from planetary spacecraft missions further extend VEPO resources to the domain of geospace and planetary interactions. Ground-based (e.g., neutron monitor) and high-altitude suborbital measurements can expand coverage to the highest energies of galactic cosmic rays affected by heliospheric interaction and of solar energetic particles. Science applications include investigation of solar flare and coronal mass ejection events. acceleration and transport of interplanetary particles within the inner heliosphere, cosmic ray interactions with planetary surfaces and atmospheres, sources of suprathermal and anomalous cosmic ray ions in the outer heliosphere, and solar cycle modulation of galactic cosmic rays. Robotic and human exploration, and eventual habitation, of planetary and space environments beyond the Earth require knowledge of radiation

  12. Virtual Energetic Particle Observatory (VEPO)

    NASA Astrophysics Data System (ADS)

    Cooper, J. F.; Lal, N.; McGuire, R. E.; Szabo, A.; Narock, T. W.; Armstrong, T. P.; Manweiler, J. W.; Patterson, J. D.; Hill, M. E.; Vandergriff, J. D.; McKibben, R. B.; Lopate, C.; Tranquille, C.

    2008-12-01

    The Virtual Energetic Particle Observatory (VEPO) focuses on improved discovery, access, and usability of heliospheric energetic particle and ancillary data products from selected spacecraft and sub-orbital instruments of the heliophysics data environment. The energy range of interest extends over the full range of particle acceleration from keV energies of suprathermal seed particles to GeV energies of galactic cosmic ray particles. Present spatial coverage is for operational and legacy spacecraft operating from the inner to the outer heliosphere, e.g. from measurements by the two Helios spacecraft to 0.3 AU to the inner heliosheath region now being traversed by the two Voyager spacecraft. This coverage will eventually be extended inward to ten solar radii by the planned NASA solar probe mission and at the same time beyond the heliopause into the outer heliosheath by continued Voyager operations. The geospace fleet of spacecraft providing near-Earth interplanetary measurements, selected magnetospheric spacecraft providing direct measurements of penetrating interplanetary energetic particles, and interplanetary cruise measurements from planetary spacecraft missions further extend VEPO resources to the domain of geospace and planetary interactions. Ground-based (e.g., neutron monitor) and high-altitude suborbital measurements can expand coverage to the highest energies of galactic cosmic rays affected by heliospheric interaction and of solar energetic particles. Science applications include investigation of solar flare and coronal mass ejection events, acceleration and transport of interplanetary particles within the inner heliosphere, cosmic ray interactions with planetary surfaces and atmospheres, sources of suprathermal and anomalous cosmic ray ions in the outer heliosphere, and solar cycle modulation of galactic cosmic rays. Robotic and human exploration, and eventual habitation, of planetary and space environments beyond the Earth require knowledge of radiation

  13. Magnetic particles

    NASA Technical Reports Server (NTRS)

    Chang, Manchium (Inventor); Colvin, Michael S. (Inventor)

    1989-01-01

    Magnetic polymer particles are formed by swelling porous, polymer particles and impregnating the particles with an aqueous solution of precursor magnetic metal salt such as an equimolar mixture of ferrous chloride and ferric chloride. On addition of a basic reagent such as dilute sodium hydroxide, the metal salts are converted to crystals of magnetite which are uniformly contained througout the pores of the polymer particle. The magnetite content can be increased and neutral buoyancy achieved by repetition of the impregnaton and neutralization steps to adjust the magnetite content to a desired level.

  14. Solid State Neutral Particle Analyzer Array on NSTX

    SciTech Connect

    K. Shinohara; D.S. Darrow; A.L. Roquemore; S.S. Medley; F.E. Cecil

    2004-05-13

    A Solid State Neutral Particle Analyzer (SSNPA) array has been installed on the National Spherical Torus Experiment (NSTX). The array consists of four chords viewing through a common vacuum flange. The tangency radii of the viewing chords are 60, 90, 100, and 120 cm. They view across the three co-injection neutral beam lines (deuterium, 80 keV (typ.) with tangency radii 48.7, 59.2, and 69.4 cm) on NSTX and detect co-going energetic ions. A silicon photodiode used was calibrated by using a mono-energetic deuteron beam source. Deuterons with energy above 40 keV can be detected with the present setup. The degradation of the performance was also investigated. Lead shots and epoxy are used for neutron shielding to reduce handling any hazardous heavy metal. This method also enables us to make an arbitrary shape to be fit into the complex flight tube.

  15. Energetic charged particles in Saturn's magnetosphere: Voyager 2 results

    SciTech Connect

    Vogt, R.E.; Chenette, D.L.; Cummings, A.C.; Garrard, T.L.; Stone, E.C.; Schardt, A.W.; Trainor, J.H.; Lal, N.; McDonald, F.B.

    1982-01-29

    Results from the cosmic-ray system on Voyager 2 in Saturn's magnetosphere are presented. During the inbound pass through the outer magnetosphere, the greater than or equal to 0.43-million-electron-volt proton flux was more intense, and both the proton and electron fluxes were more varible, than previously observed. These changes are attributed to the influence on the magnetosphere of variations in the solar wind conditions. Outbound, beyond 18 Saturn radii, impulsive bursts of 0.14- to > 1.0-million-electron-volt electrons were observed. In the inner magnetosphere, the charged particle absorption signatures of Mimas, Enceladus, and Tethys are used to constrain the possible tilt and offset of Saturn's internal magnetic dipole. At approx. 3 Saturn radii, a transient decrease was observed in the electron flux which was not due to Mimas. Characteristics of this decrease suggest the existence of additional material, perhaps another satellite, in the orbit of Mimas.

  16. Scattering and Absorption by Nonspherical Particles in Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    West, Robert A.

    2005-01-01

    The atmospheres of Mars, the giant planets, and Titan all support populations of nonspherical particles. Analyses of observations of these atmospheres therefore rely on an understanding of the optical properties of nonspherical particles. We can glean information on particle size and composition from the wavelength dependence of the optical depth and from the shape of the forward peak of the scattering phase function. Additional information comes from polarization measurements which have been especially fruitful for Titan's haze. The Mars atmosphere contains mineral dust particles with effective radii near 1.6 micro meters, and water ice particles with radii between about 1 and 4 micro meters. The uppermost tropospheric hazes in Jupiter and Saturn are composed of ice crystals of ammonia, water and possibly traces of ammonium hydrosulfide, Methane ice and hydrogen sulfide ice are present in the atmospheres of Uranus and Neptune. Size estimation for these hazes in the giant planets is difficult, and even the expected spectral signatures are elusive, Titan's haze is both forward scattering and strongly polarized - a combination which points toward a fractal aggregate struc1.ure of 10 - 100 or more organic monomers whose radius is about 0.06 micro meters. Polar stratospheric hazes on Jupiter and Saturn also display this characteristic.

  17. Dirac-Hartree-Bogoliubov calculation for spherical and deformed hot nuclei: Temperature dependence of the pairing energy and gaps, nuclear deformation, nuclear radii, excitation energy, and entropy

    NASA Astrophysics Data System (ADS)

    Lisboa, R.; Malheiro, M.; Carlson, B. V.

    2016-02-01

    Background: Unbound single-particle states become important in determining the properties of a hot nucleus as its temperature increases. We present relativistic mean field (RMF) for hot nuclei considering not only the self-consistent temperature and density dependence of the self-consistent relativistic mean fields but also the vapor phase that takes into account the unbound nucleon states. Purpose: The temperature dependence of the pairing gaps, nuclear deformation, radii, binding energies, entropy, and caloric curves of spherical and deformed nuclei are obtained in self-consistent RMF calculations up to the limit of existence of the nucleus. Method: We perform Dirac-Hartree-Bogoliubov (DHB) calculations for hot nuclei using a zero-range approximation to the relativistic pairing interaction to calculate proton-proton and neutron-neutron pairing energies and gaps. A vapor subtraction procedure is used to account for unbound states and to remove long range Coulomb repulsion between the hot nucleus and the gas as well as the contribution of the external nucleon gas. Results: We show that p -p and n -n pairing gaps in the S10 channel vanish for low critical temperatures in the range Tcp≈0.6 -1.1 MeV for spherical nuclei such as 90Zr, 124Sn, and 140Ce and for both deformed nuclei 150Sm and 168Er. We found that superconducting phase transition occurs at Tcp=1.03 Δp p(0 ) for 90Zr, Tcp=1.16 Δp p(0 ) for 140Ce, Tcp=0.92 Δp p(0 ) for 150Sm, and Tcp=0.97 Δp p(0 ) for 168Er. The superfluidity phase transition occurs at Tcp=0.72 Δn n(0 ) for 124Sn, Tcp=1.22 Δn n(0 ) for 150Sm, and Tcp=1.13 Δn n(0 ) for 168Er. Thus, the nuclear superfluidity phase—at least for this channel—can only survive at very low nuclear temperatures and this phase transition (when the neutron gap vanishes) always occurs before the superconducting one, where the proton gap is zero. For deformed nuclei the nuclear deformation disappear at temperatures of about Tcs=2.0 -4.0 MeV , well above the

  18. Measurements of size and composition of particles in polar stratospheric clouds from infrared solar absorption spectra

    NASA Technical Reports Server (NTRS)

    Kinne, S.; Toon, O. B.; Toon, G. C.; Farmer, C. B.; Browell, E. V.; Mccormick, M. P.

    1989-01-01

    Results are presented on polar stratospheric cloud (PSC) observations, based on IR measurements of solar extinction, made by the airborne JPL Mark IV interferometer during the Airborne Antarctic Ozone Expedition in 1987, together with the instrumentation and the theoretical aspects of data analysis. Thirty-three PSC cases were analyzed and categorized into two types, I and II, which were found to occur at different altitudes during September. Type I clouds, seen at altitudes above 15 km, contained particles with radii of about 0.5 micarons and nitric acid concentrations greater than 40 percent, while type II clouds, found usually below 15 km, contained particles with radii of 6 microns and larger, composed of water ice. In addition, particles of larger than the 15-micron-size detection limit were encounterd.

  19. Particle preconcentrator

    DOEpatents

    Linker, K.L.; Conrad, F.J.; Custer, C.A.; Rhykerd, C.L. Jr.

    1998-12-29

    An apparatus and method are disclosed for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents. 3 figs.

  20. Particle preconcentrator

    SciTech Connect

    Linker, K.L.; Conrad, F.J.; Custer, C.A.; Rhykerd, C.L. Jr

    2000-07-11

    An apparatus and method are disclosed for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a previous screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents.

  1. Particle preconcentrator

    SciTech Connect

    Linker, Kevin L.; Conrad, Frank J.; Custer, Chad A.; Rhykerd, Jr., Charles L.

    1998-01-01

    An apparatus and method for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents.

  2. Particle preconcentrator

    SciTech Connect

    Linker, Kevin L.; Conrad, Frank J.; Custer, Chad A.; Rhykerd, Jr., Charles L.

    2005-09-20

    An apparatus and method for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents.

  3. Particle preconcentrator

    SciTech Connect

    Linker, Kevin L.; Conrad, Frank J.; Custer, Chad A.; Rhykerd, Jr., Charles L.

    2000-01-01

    An apparatus and method for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents.

  4. A Comparison of Observationally Determined Radii with Theoretical Radius Predictions for Short-Period Transiting Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Laughlin, Gregory; Wolf, Aaron; Vanmunster, Tonny; Bodenheimer, Peter; Fischer, Debra; Marcy, Geoff; Butler, Paul; Vogt, Steve

    2005-03-01

    Two extrasolar planets, HD 209458b and TrES-1, are currently known to transit bright parent stars for which physical properties can be accurately determined. The two transiting planets have very similar masses and periods and hence invite detailed comparisons between their observed and theoretically predicted properties. In this paper, we carry out these comparisons. We first report photometric and spectroscopic follow-up observations of TrES-1, and we use these observations to obtain improved estimates for the planetary radius, Rpl=(1.08+/-0.05)RJ, and the planetary mass, Mpl=(0.729+/-0.036)MJ. We also confirm that the inclination estimate of the planetary orbit as i=88.2d. These values agree with those obtained by Alonso et al. in their discovery paper, but the uncertainty in the planet radius has been improved as a result of both high-cadence photometry of two full transits and from independent radius determinations for the V=11.8 K0 V parent star. We derive estimates for the TrES-1 stellar parameters of R*/Rsolar=0.83+/-0.03 (by combining independent estimates from stellar models, high-resolution spectra, and transit light curve fitting) M*/Msolar=0.87+/-0.05 (via fitting to evolutionary tracks), Teff=5214+/-23K, [Me/H]=0.001+/-0.04, rotational velocity Vsin(i)=1.08+/-0.3kms-1, logg=4.52+/-0.05dex, logL*/Lsolar=-0.32, d=157+/-6pc, and an age of τ=4+/-2Gyr. These estimates of the physical properties of the system allow us to compute evolutionary models for the planet that result in a predicted radius of Rpl=1.05RJ for a model that contains an incompressible 20 M⊕ core and a radius Rpl=1.09RJ for a model without a core. We use our grids of planetary evolution models to show that, with standard assumptions, our code also obtains good agreement with the observed radii of the other recently discovered transiting planets, including OGLE-TR-56b, OGLE-TR-111b, OGLE-TR-113b, and OGLE-TR-132b. We report an updated radius for HD 209458b of Rpl=(1.32+/-0.05)RJ, based on

  5. Two high resolution velocity vector analyzers for cosmic dust particles

    NASA Technical Reports Server (NTRS)

    Auer, S.

    1975-01-01

    Two new methods are described to measure velocities and angles of incidence of charged cosmic dust particles with precisions of about 1% and 1 deg, respectively. Both methods employ four one-dimensional position-sensitive detectors in series. The first method utilizes a charge-dividing technique while the second utilizes a time-of-flight technique for determining the position of a particle inside the instrument. The velocity vectors are measured although mechanical interaction between the particle and the instrument is completely avoided. Applications to cosmic dust composition and collection experiments are discussed. The range of radii of measurable particles is from about 0.01 to 100 microns at velocities from 1 to 80 km/sec.

  6. Elementary particles

    NASA Astrophysics Data System (ADS)

    Fritzsch, Harald; Heusch, Karin

    Introduction -- Electrons and atomic nuclei -- Quantum properties of atoms and particles -- The knives of Democritus -- Quarks inside atomic nuclei -- Quantum electrodynamics -- Quantum chromodynamics -- Mesons, baryons, and quarks -- Electroweak interactions -- Grand unification -- Conclusion.

  7. Magnetic particles

    NASA Technical Reports Server (NTRS)

    Chang, Manchium (Inventor); Colvin, Michael S. (Inventor); Rembaum, Alan (Inventor); Richards, Gil F. (Inventor)

    1987-01-01

    Metal oxide containing polymers and particularly styrene, acrylic or protein polymers containing fine, magnetic iron oxide particles are formed by combining a NO.sub.2 -substituted polymer with an acid such as hydrochloric acid in the presence of metal, particularly iron particles. The iron is oxidized to fine, black Fe.sub.3 O.sub.4 particles which deposit selectively on the polymer particles. Nitrated polymers are formed by reacting functionally substituted, nitrated organic compounds such as trinitrobenzene sulfonate or dinitrofluoro benzene with a functionally coreactive polymer such as an amine modified acrylic polymer or a protein. Other transition metals such as cobalt can also be incorporated into polymers using this method.

  8. Elementary Particles

    ERIC Educational Resources Information Center

    Parham, R.

    1974-01-01

    Presents the text of a speech given to a conference of physics teachers in which the full spectrum of elementary particles is given, along with their classification. Also includes some teaching materials available on this topic. (PEB)

  9. Comparative Morphology of Solar Relativistic Particle Events

    NASA Astrophysics Data System (ADS)

    Kocharov, Leon; Klassen, Andreas; Valtonen, Eino; Usoskin, Ilya; Ryan, James M.

    2015-09-01

    Time profiles of the 0.25-10 MeV electrons and the ˜(0.1-1) GeV nucleon-1 protons and helium associated with two solar coronal mass ejections (CMEs) are analyzed with a newly formulated method based on modeling of the particle transport in the interplanetary medium. With the modeling, we fit the observed angular distribution of solar particles and infer, for a particular particle instrument and magnetic field orientation, the time delay of the particle registration at 1 AU in respect to the solar source. Then, after the time offset removal, intensity re-normalization and background equalization, the time-intensity profiles of high-energy protons, helium and electrons in different energy channels are superposed and compared. The comparison reveals episodes of remarkable coincidence of different profiles, as well as episodes of essentially different behavior. It implies at least three sources of solar high-energy particles operating in a single event. The first, short-duration source emits electrons next to the flare's impulsive phase and CME liftoff. The second source gradually rises and continues for more than an hour, emitting electrons and lower energy protons, which is consistent with shock acceleration on open magnetic field lines extending to solar wind. An another, third source is the main source of relativistic ions in space. It is retarded in respect to the flare's impulsive phase and may be associated with a structure encountered by the shock within a few solar radii from the Sun.

  10. Dynamical behaviour of interstellar dust particles in the solar system

    NASA Astrophysics Data System (ADS)

    Kocifaj, Miroslav; Klačka, Jozef

    2004-11-01

    Motion and possible capture of interstellar dust particles (ISDPs) in the Solar System are investigated. Gravitational force of the Sun, solar electromagnetic and corpuscular radiation and interplanetary magnetic field are considered. The effect of solar electromagnetic radiation plays an important role in the sense that nonspherical ISDPs can be captured (and survive) much more effectively than spherical particles. It turns out that particles of effective radii ≈ 0.4 μm, moving initially near the solar equatorial plane and with impact parameter 400 RS ≲ b ≲ 500 RS (solar radii) exhibit a high probability of capture and survival in the Solar System. Only a very small number of spherical particles can be captured. Survived nonspherical ISDPs orbiting around the Sun are characterized by a quantity analogous to the Kepler's third law: /T2, where T is orbital period and is time average of cubed solar distance over the period T. The value of the quantity /T2 is 0.673 ± 0.002 [AU3 /year2 ].