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Sample records for bonner sphere detectors

  1. Response Matrix of a Bonner Spheres Spectrometer with {sup 3} He Detector

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H.R.; Manzanares A, E.; Hernandez D, V.M. [Unidades Academicas de Estudios Nucleares, Ing. Electrica y Matematicas, Universidad Autonoma de Zacatecas, Apdo. Postal 336, 98000 Zacatecas (Mexico)]. e-mail: rvega@cantera.reduaz.mx

    2004-07-01

    Using MCNP code the response matrix of a Bonner spheres spectrometer was calculated. The spectrometer has a 3.2 cm-diameter thermal neutron detector; this is a {sup 3} He-filled proportional counter that is located at the center of a set of polyethylene spheres. The response was calculated for 0, 3, 5, 6, 8, 10, 12 and 16 inches-diameter polyethylene spheres for neutrons whose energy goes from 10-9 to 20 MeV. The response matrix was compared with a set of responses measured with several monoenergetic neutron sources, from this comparison calculated matrix is in agreement with the experimental results. Also this matrix was compared against the response matrix calculated for the PTB C spectrometer, Nevertheless that calculation was carried out using a detailed model to describe the proportional counter both matrices were in agreement, small differences are observed in the bare case because the difference in the model used during calculations. Other differences are in some spheres for 14.8 and 20 MeV neutrons probable due to the differences in the cross sections used during both calculations. (Author)

  2. Neutron spectrometry using artificial neural networks for a Bonner sphere spectrometer with a {sup 3}He detector

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz R, J. M. [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica, Apdo. Postal 336, 98000 Zacatecas (Mexico); Martinez B, M. R.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Apdo. Postal 336, 98000 Zacatecas (Mexico); Gallego D, E.; Lorente F, A. [Universidad Politecnica de Madrid, Departamento de Ingenieria Nuclear, ETSI Industriales, C. Jose Gutierrez Abascal 2, 28006 Madrid (Spain); Mendez V, R.; Los Arcos M, J. M.; Guerrero A, J. E., E-mail: morvymm@yahoo.com.m [CIEMAT, Laboratorio de Metrologia de Radiaciones Ionizantes, Avda. Complutense 22, 28040 Madrid (Spain)

    2011-02-15

    Neutron spectra unfolding and dose equivalent calculation are complicated tasks in radiation protection, are highly dependent of the neutron energy, and a precise knowledge on neutron spectrometry is essential for all dosimetry-related studies as well as many nuclear physics experiments. In previous works have been reported neutron spectrometry and dosimetry results, by using the artificial neural networks (Ann) technology as alternative solution, starting from the count rates of a Bonner spheres system with a {sup 6}LiI(Eu) thermal neutrons detector, 7 polyethylene spheres and the UTA4 response matrix with 31 energy bins. In this work, an Ann was designed and optimized by using the RDAnn methodology for the Bonner spheres system used at CIEMAT Spain, which is composed of a {sup 3}He neutron detector, 12 moderator spheres and a response matrix for 72 energy bins. For the Ann design process a neutrons spectra catalogue compiled by the IAEA was used. From this compilation, the neutrons spectra were converted from lethargy to energy spectra. Then, the resulting energy fluence spectra were re-bin ned by using the MCNP code to the corresponding energy bins of the {sup 3}He response matrix before mentioned. With the response matrix and the re-bin ned spectra the counts rate of the Bonner spheres system were calculated and the resulting re-bin ned neutrons spectra and calculated counts rate were used as the Ann training data set. (Author)

  3. A Bonner Sphere Spectrometer for pulsed fields.

    Science.gov (United States)

    Aza, E; Dinar, N; Manessi, G P; Silari, M

    2016-02-01

    The use of conventional Bonner Sphere Spectrometers (BSS) in pulsed neutron fields (PNF) is limited by the fact that proportional counters, usually employed as the thermal neutron detectors, suffer from dead time losses and show severe underestimation of the neutron interaction rate, which leads to strong distortion of the calculated spectrum. In order to avoid these limitations, an innovative BSS, called BSS-LUPIN, has been developed for measuring in PNF. This paper describes the physical characteristics of the device and its working principle, together with the results of Monte Carlo simulations of its response matrix. The BSS-LUPIN has been tested in the stray neutron field at the CERN Proton Synchrotron, by comparing the spectra obtained with the new device, the conventional CERN BSS and via Monte Carlo simulations.

  4. Photoneutron spectrum measured with Bonner Spheres in Planetary method mode

    Energy Technology Data Exchange (ETDEWEB)

    Benites R, J. [Centro Estatal de Cancerologia de Nayarit, Servicio de Seguridad Radiologica, Calz. de la Cruz 118 Sur, 63000 Tepic, Nayarit (Mexico); Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Apdo. Postal 336, 98000 Zacatecas (Mexico); Velazquez F, J., E-mail: jlbenitesr@prodigy.net.mx [Universidad Autonoma de Nayarit, Posgrado en Ciencias Biologico Agropecuarias, Carretera Tepic-Compostela Km 9, 63780 Jalisco-Nayarit (Mexico)

    2012-10-15

    We measured the spectrum of photoneutrons at 100 cm isocenter linear accelerator (Linac) Varian ix operating at 15 MV Bremsstrahlung mode. In this process was used a radiation field of 20 x 20 cm{sup 2} at a depth of 5 cm in a solid water phantom with dimensions of 30 x 30 x 15 cm{sup 3}. The measurement was performed with a system using it Bonner Spheres spectrometric method Planetary mode. As neutron detector of the spectrometer is used thermoluminescent dosimeters pairs of type 600 and 700. (Author)

  5. The optimization study of Bonner sphere in the epi-thermal neutron irradiation field for BNCT.

    Science.gov (United States)

    Ueda, H; Tanaka, H; Maruhashi, A; Ono, K; Sakurai, Y

    2011-12-01

    The optimization study on the Bonner sphere in the epi-thermal neutron irradiation field for BNCT was done for the moderator material, moderator size, and activation foils as a neutron detector in the sphere. The saturated activity for the activation foil was obtained from the calculated response, and the effective energy range for each Bonner sphere was determined from the saturated activity. We can see that boric acid solution moderator is suitable for the spectrum measurement of a epi-thermal neutron irradiation field.

  6. The Effect of the Choice or Response Matrix on Unfolded Bonner Sphere Spectra.

    Science.gov (United States)

    1984-12-31

    cylindrical, 4 m high x 4 mm dia., europium- activated lithium iodide scintillation crystal as the thermal neutron detector in the centers of polyethylene... Neutroniques Avec les Spheres de Bonner Establissement d’une Matrice Log-Normale de Reference," CEA-N-2241, Commisariat d l’Energie Atomique - France (1981

  7. Upgrade of neutron energy spectrometer with single multilayer bonner sphere using onion-like structure

    Energy Technology Data Exchange (ETDEWEB)

    Mizukpshi, Tomoaki; Watanabe, Kenichi; Yamazaki, Atsushi; Uritan, Akira [Nagoya University, Nagoya (Japan); Iguchi, Tetsuo; Ogata, Tomohiro; Muramatsu, Takashi [Mitsubishi Heavy Industries Ltd., Kobe(Japan)

    2016-09-15

    In order to measure neutron energy spectra, the conventional Bonner Sphere Spectrometers (BSS) are widely used. In this spectrometer, several measurements with different size Bonner spheres are required. Operators should, therefore, place these spheres in several times to a measurement point where radiation dose might be relatively high. In order to reduce this effort, novel neutron energy spectrometer using an onion-like single Bonner sphere was proposed in our group. This Bonner sphere has multiple sensitive spherical shell layers in the single sphere. In this spectrometer, a band-shaped thermal neutron detection medium, which consists of a LiF-ZnS mixed powder scintillator sheet and a wavelength-shifting (WLS) fiber readout, was looped to each sphere at equal angular intervals. Amount of LiF neutron converter is reduced near polar region, where the band-shaped detectors are concentrated, in order to uniform the directional sensitivity. The LiF-ZnS mixed powder has an advantage of extremely high light yield. However, since it is opaque, scintillation photons cannot be collect uniformly. This type of detector shows no characteristic shape in the pulse height spectrum. Subsequently, it is difficult to set the pulse height discrimination level. This issue causes sensitivity fluctuation due to gain instability of photodetectors and/or electric modules. In order to solve this problem, we propose to replace the LiF-ZnS mixed powder into a flexible and Transparent RUbber SheeT type LiCaAlF6 (TRUST LiCAF) scintillator. TRUST LiCAF scintillator can show a peak shape corresponding to neutron absorption events in the pulse height spectrum. We fabricated the prototype detector with five sensitive layers using TRUST LiCAF scintillator and conducted basic experiments to evaluate the directional uniformity of the sensitivity. The fabricated detector shows excellent directional uniformity of the neutron sensitivity.

  8. The response of a Bonner Sphere spectrometer to charged hadrons

    CERN Document Server

    Agosteo, S; Fassò, A; Silari, M

    2004-01-01

    Bonner sphere spectrometers (BSSs) are employed in neutron spectrometry and dosimetry since many years. Recent developments have seen the addition to a conventional BSS of one or more detectors (moderator plus thermal neutron counter) specifically designed to improve the overall response of the spectrometer to neutrons above 10 MeV. These additional detectors employ a shell of material with a high mass number (such as lead) within the polyethylene moderator, in order to slow down high-energy neutrons via (n, xn) reactions. A BSS can be used to measure neutron spectra both outside accelerator shielding and from an unshielded target. Measurements were recently performed at CERN of the neutron yield and spectral fluence at various angles from unshielded, semithick copper, silver and lead targets, bombarded by a mixed proton/pion beam with 40 GeV per c momentum. These experiments have provided evidence that under certain circumstances, the use of lead-enriched moderators may present a problem: these detectors wer...

  9. Development of a Bonner Sphere Neutron Spectrometer from a Commercial Neutron Dosimeter

    CERN Document Server

    Chu, M C; Kwok, T; Leung, J K C; Lin, Y C; Liu, H; Luk, K B; Ngai, H Y; Pun, C S J; Wong, H L H

    2016-01-01

    Bonner Spheres have been used widely for the measurement of neutron spectra with neutron energies ranged from thermal up to at least 20 MeV. A Bonner Sphere neutron spectrometer (BSS) was developed by extending a Berthold LB 6411 neutron-dose-rate meter. The BSS consists of a $^{3}$He thermal-neutron detector with integrated electronics, a set of eight polyethylene spherical shells and two optional lead shells of various sizes. The response matrix of the BSS was calculated with GEANT4 Monte Carlo simulation. The BSS had a calibration uncertainty of $\\pm 8.6\\%$ and a detector background rate of $(1.57 \\pm 0.04) \\times 10^{-3}$ s$^{-1}$. A spectral unfolding code NSUGA was developed. The NSUGA code utilizes genetic algorithms and has been shown to perform well in the absence of a priori information.

  10. The response of a bonner sphere spectrometer to charged hadrons.

    Science.gov (United States)

    Agosteo, S; Dimovasili, E; Fassò, A; Silari, M

    2004-01-01

    Bonner sphere spectrometers (BSSs) are employed in neutron spectrometry and dosimetry since many years. Recent developments have seen the addition to a conventional BSS of one or more detectors (moderator plus thermal neutron counter) specifically designed to improve the overall response of the spectrometer to neutrons above 10 MeV. These additional detectors employ a shell of material with a high mass number (such as lead) within the polyethylene moderator, in order to slow down high-energy neutrons via (n,xn) reactions. A BSS can be used to measure neutron spectra both outside accelerator shielding and from an unshielded target. Measurements were recently performed at CERN of the neutron yield and spectral fluence at various angles from unshielded, semi-thick copper, silver and lead targets, bombarded by a mixed proton/pion beam with 40 GeV per c momentum. These experiments have provided evidence that under certain circumstances, the use of lead-enriched moderators may present a problem: these detectors were found to have a significant response to the charged hadron component accompanying the neutrons emitted from the target. Conventional polyethylene moderators show a similar behaviour but less pronounced. These secondary hadrons interact with the moderator and generate neutrons, which are in turn detected by the counter. To investigate this effect and determine a correction factor to be applied to the unfolding procedure, a series of Monte Carlo simulations were performed with the FLUKA code. These simulations aimed at determining the response of the BSS to charged hadrons under the specific experimental situation. Following these results, a complete response matrix of the extended BSS to charged pions and protons was calculated with FLUKA. An experimental verification was carried out with a 120 GeV per c hadron beam at the CERF facility at CERN.

  11. Neutron spectrometry and dosimetry with neural networks and Bonner spheres: a study to reduce the spheres number; Espectrometria y dosimetria neutronica con redes neuronales y esferas Bonner: un estudio para reducir el numero de esferas

    Energy Technology Data Exchange (ETDEWEB)

    Espinoza G, J. G.; Martinez B, M. R.; Leon P, A. A.; Hernandez P, C. F.; Castaneda M, V. H.; Solis S, L. O.; Castaneda M, R.; Ortiz R, J. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Av. Ramon Lopez Velarde 801, Col. Centro, 98000 Zacatecas, Zac. (Mexico); Mendez, R. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Laboratorio de Patrones Neutronicos, Av. Complutense 22, 28040 Madrid (Spain); Gallego, E. [Universidad Politecnica de Madrid, Departamento de Ingenieria Nuclear, C. Jose Gutierrez Abascal 2, 28006 Madrid (Spain); De Sousa L, M. A. [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Av. Pte. Antonio Carlos 6627, Pampulha, 31270-901 Belo Horizonte, MG (Brazil)

    2016-10-15

    For neutron spectrometry and neutron dosimetry, the Bonner spheres spectrometric system has been the most widely used system, however, the number, size and weight of the spheres composing the system, as well as the need to use a reconstruction code and the long periods of time used to carry out the measurements are some of the disadvantages of this system. For the reconstruction of the spectra, different techniques such as artificial neural networks of reverse propagation have been used. The objective of this work was to reduce the number of Bonner spheres and to use counting speeds in a reverse propagation neural network, optimized by means of the robust design methodology, to reconstruct the neutron spectra. For the design of the neural network we used the neutron spectra of the IAEA and the response matrix of the Bonner spheres with {sup 6}LiI(Eu) detector. The performance of the network was compared; using 7 Bonner spheres against other cases where only 2 and one sphere are used. The network topologies were trained 36 times for each case keeping constant the objective error (1E(-3)), the training algorithm was trains cg and the robust design methodology to determine the best network architectures. With these, the best and worst results were compared. The results obtained using 7 spheres were similar to those with the 5-in sphere, however is still in an information analysis stage. (Author)

  12. Response matrix of an extended Bonner sphere system

    CERN Document Server

    Vylet, V

    2002-01-01

    We have developed a system of Bonner spheres designed for use around high-energy accelerators. The upper energy limit of the system was extended using a lead radiator, which acts as an energy converter via the (n,xn) reaction. In addition, we use sup 1 sup 1 C activation as an additional component integrated into the system and the spectra unfolding process. In the first version of the system, the lead radiator was present in only one sphere with diameter of 30.48 cm. The object of the present work was to investigate the geometry of the lead radiator and its use in moderators of several different sizes. As a result, we have developed a modular design and calculated the response matrix of the new system.

  13. NEMUS--the PTB Neutron Multisphere Spectrometer Bonner spheres and more

    CERN Document Server

    Wiegel, B

    2002-01-01

    The original Bonner sphere spectrometer as it is used and characterized by PTB consists of 12 polyethylene spheres with diameters from 7.62 cm (3'') to 45.72 cm (18'') and a sup 3 He-filled spherical proportional counter used as a central thermal-neutron-sensitive detector and as a bare or cadmium-shielded bare detector. In this paper, a set of four new spheres made of polyethylene with copper or lead inlets is introduced. All spheres are less than 18 kg in mass and their responses to high energy neutrons increase with energy as a result of the increasing (n,xn) cross-sections of copper and lead. The fluence response matrix was calculated up to 10 GeV using an extended neutron cross-section library (LA150) and the MCNP(X) Monte Carlo code. Calibration measurements with neutron energies up to 60 MeV were used to compare the calculated response functions to measured values. For measurements outside the laboratory, a miniaturized, battery-powered electronic set-up was developed. This system with the additional, ...

  14. BUMS--Bonner sphere Unfolding Made Simple an HTML based multisphere neutron spectrometer unfolding package

    CERN Document Server

    Sweezy, J; Veinot, K

    2002-01-01

    A new multisphere neutron spectrometer unfolding package, Bonner sphere Unfolding Made Simple (BUMS) has been developed that uses an HTML interface to simplify data input and code execution for the novice and the advanced user. This new unfolding package combines the unfolding algorithms contained in other popular unfolding codes under one easy to use interface. The interface makes use of web browsing software to provide a graphical user interface to the unfolding algorithms. BUMS integrates the SPUNIT, BON, MAXIET, and SAND-II unfolding algorithms into a single package. This package also includes a library of 14 response matrices, 58 starting spectra, and 24 dose and detector responses. BUMS has several improvements beyond the addition of unfolding algorithms. It has the ability to search for the most appropriate starting spectra. Also, plots of the unfolded neutron spectra are automatically generated. The BUMS package runs via a web server and may be accessed by any computer with access to the Internet at h...

  15. Determining the neutron spectrum of 241Am-Be and 252Cf sources using bonner sphere spectrometer

    Directory of Open Access Journals (Sweden)

    M.A Varshabi

    2016-06-01

    Full Text Available Bonner spheres system is one of the ways of measuring neutron energy distribution which is often applied in spectrometry and neutron dosimetry. This system includes a thermal neutron detector, being located in the center of several polyethylene spheres, and it is still workable due to the isotropic response of the system which in turn is derived from the spherical symmetry of moderators and the broad measurable range of the energy. In order to practically use this spectrometer, it is necessary to calibrate this system using standard neutron sources. This research aimed to determine the calibration factor of Bonner spheres spectrometry system and energy spectrum of two standard 241Am-Be and 252Cf sources in the atomic energy organization. Calibration and experimental measurement were done via the two standard sources. The response vector of each detector was derived by using MCNPX simulation code, based on the Monte Carlo method. The spectra unfolding of this system was performed through iterative method using the SPUNIT code done in software NSDUAZ6LiI and BUMS. 

  16. Monte Carlo calculations and experimental results of Bonner spheres systems with a new cylindrical Helium-3 proportional counter

    CERN Document Server

    Müller, H; Bouassoule, T; Fernández, F; Pochat, J L; Tomas, M; Van Ryckeghem, L

    2002-01-01

    The experimental results on neutron energy spectra, integral fluences and equivalent dose measurements performed by means of a Bonner sphere system placed inside the containment building of the Vandellos II Nuclear Power Plant (Tarragona, Spain) are presented. The equivalent dose results obtained with this system are compared to those measured with different neutron area detectors (Berthold, Dineutron, Harwell). A realistic geometry model of the Bonner sphere system with a new cylindrical counter type 'F' (0,5NH1/1KI--Eurisys Mesures) and with a set of eight polyethylene moderating spheres is described in detail. The response function in fluence of this new device, to mono-energetic neutrons from thermal energy to 20 MeV, is calculated by the MCNP-4B code for each moderator sphere. The system has been calibrated at IPSN Cadarache facility for ISO Am-Be calibrated source and thermal neutron field, then the response functions were confirmed by measurements at PTB (Germany) for ISO recommended energies of mono-e...

  17. Monte Carlo calculations and experimental results of Bonner spheres systems with a new cylindrical Helium-3 proportional counter

    Science.gov (United States)

    Muller, H.; Fernández, F.; Van Ryckeghem, L.; Alexandre, P.; Bouassoule, T.; Pochat, J.-L.; Tomas, M.

    2002-01-01

    The experimental results on neutron energy spectra, integral fluences and equivalent dose measurements performed by means of a Bonner sphere system placed inside the containment building of the Vandellòs II Nuclear Power Plant (Tarragona, Spain) are presented. The equivalent dose results obtained with this system are compared to those measured with different neutron area detectors (Berthold, Dineutron, Harwell). A realistic geometry model of the Bonner sphere system with a new cylindrical counter type "F" (0,5NH1/1KI—Eurisys Mesures) and with a set of eight polyethylene moderating spheres is described in detail. The response function in fluence of this new device, to mono-energetic neutrons from thermal energy to 20 MeV, is calculated by the MCNP-4B code for each moderator sphere. The system has been calibrated at IPSN Cadarache facility for ISO Am-Be calibrated source and thermal neutron field, then the response functions were confirmed by measurements at PTB (Germany) for ISO recommended energies of mono-energetic neutrons and with the CANEL IPSN facility which simulates realistic fields.

  18. Application of neural networks for unfolding neutron spectra measured by means of Bonner spheres and activation foils

    CERN Document Server

    Braga, C C

    2001-01-01

    A neural network structure has been used for unfolding neutron spectra measured by means of a Bonner Sphere Spectrometer set and a foil activation set using several neutron induced reactions. The present work used the SNNS (Stuttgart Neural Network Simulator) as the interface for designing, training and validation of the Multilayer Perceptron network. The back-propagation algorithm was applied. The Bonner Sphere set chosen has been calibrated at the National Physical Laboratory, United Kingdom, and uses gold activation foils as thermal neutron detectors. The neutron energy covered by the response functions goes from 0.0001 eV to 14 MeV. The foil activation set chosen has been irradiated at the IEA-R1 research reactor and measured at the Nuclear Metrology Laboratory of IPEN-CNEN/SP. Two types of neutron spectra were numerically investigated: monoenergetic and continuous The unfolded spectra were compared to a conventional method using code SAND-II as part of the neutron dosimetry system SAIPS. Good results wer...

  19. NSDUAZ unfolding package for neutron spectrometry and dosimetry with Bonner spheres

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R.; Martinez B, M. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Ortiz R, J. M., E-mail: fermineutron@yahoo.com [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica, Av. Ramon Lopez Velarde 801, Col. Centro, 98000 Zacatecas (Mexico)

    2011-10-15

    NSDUAZ (Neutron Spectrometry and Dosimetry for the Universidad Autonoma de Zacatecas) is a user friendly neutron unfolding package for Bonner sphere spectrometer with {sup 6}Lil(Eu) developed under Lab View environment. Unfolding is carried out using a recursive iterative procedure with the SPUNIT algorithm, where the starting spectrum is obtained from a library initial guess spectrum to start the iterations, the package include a statistical procedure based on the count rates relative to the count rate in the 8 inches-diameter sphere to select the initial spectrum. Neutron spectrum is unfolded in 32 energy groups ranging from 10{sup -8} up to 231.2 MeV. (Author)

  20. Neutron reference spectra measurements with the Bonner multi-spheres spectrometer; Medidas de espectros de referencia de neutrons com o espectrometro de multiesferas de Bonner

    Energy Technology Data Exchange (ETDEWEB)

    Lemos Junior, Roberto Mendonca de

    2004-07-01

    This paper aims to define a procedure to use the Bonner Multisphere Spectrometer with a {sup 6}LiI(Eu) detector in order to determine of neutron spectra. It was measured {sup 238}PuBe spectra and same of reference ({sup 241}AmBe, {sup 252}Cf e {sup 252}Cf+D{sub 2}O) published in ISO 8529-1 (2001) Norm. The data were processed by a computer program (BUNKI), which presents the results in neutrons energy fluency. Each input parameter of the program was studied in order to establish their influence in the adjustment result. The environment dose equivalent rate obtained placing the detector 1 m from the {sup 241}AmBe source was 122 {+-} 4 {mu}Sv/h with 7% of uncertainty and 95% of confidence level. The procedure established in this work was tested with the {sup 238}PuBe spectrum, obtaining an environment dose equivalent rate of 286 {+-} 9 {mu}Sv/h, 8% lower than the value measured experimentally used as reference. Through this procedure will be possible to measure neutron spectra in different work places where neutrons sources are used. Knowing these spectra, it will be possible to evaluate which area monitors, are more suitable, as well as, to study better the response of individual neutron monitors, as for instance, to obtain a conversion coefficient more appropriate to the albedo dosimeter used in different work places. As the measurements need a long time to be accomplished, the work optimization is fundamental to reduce the exposing time of the Bonner spectrometer operator. For this reason, an important parameter examined in this paper was the possibility of reducing the number of spheres used during the measurement without changing the final result. Considering the radiation protection standards, this parameter has a huge importance when the measurements are performed in work places where the neutron fluency and gamma rate offer risks to the operator's health, as for instance, in nuclear centrals. Studying this parameter, it was possible to conclude that

  1. Calibration of a Bonner sphere extension (BSE) for high-energy neutron spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Howell, R.M., E-mail: rhowell@mdanderson.or [UT M.D. Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030 (United States); Burgett, E.A. [Georgia Institute of Technology, 900 Atlantic Drive, Atlanta, GA (United States); Wiegel, B. [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany); Hertel, N.E. [Georgia Institute of Technology, 900 Atlantic Drive, Atlanta, GA (United States)

    2010-12-15

    In a recent work, we constructed modular multisphere system which expands upon the design of an existing, commercially available Bonner sphere system by adding concentric shells of copper, tungsten, or lead. Our modular multisphere system is referred to as the Bonner Sphere Extension (BSE). The BSE was tested in a high energy neutron beam (thermal to 800 MeV) at Los Alamos Neutron Science Center and provided improvement in the measurement of the neutron spectrum in the energy regions above 20 MeV when compared to the standard BSS (and). However, when the initial test of the system was carried out at LANSCE, the BSE had not yet been calibrated. Therefore the objective of the present study was to perform calibration measurements. These calibration measurements were carried-out using monoenergetic neutron ISO 8529-1 reference beams at the Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany. The following monoenergetic reference beams were used for these experiments: 14.8 MeV, 1.2 MeV, 565 keV, and 144 keV. Response functions for the BSE were calculated using the Monte Carlo N-Particle Code, eXtended (MCNPX). The percent difference between the measured and calculated responses was calculated for each sphere and energy. The difference between measured and calculated responses for individual spheres ranged between 7.9% and 16.7% and the arithmetic mean for all spheres was (10.9 {+-} 1.8)%. These sphere specific correction factors will be applied for all future measurements carried out with the BSE.

  2. Calibration of a Bonner sphere extension (BSE) for high-energy neutron spectrometry.

    Science.gov (United States)

    Howell, R M; Burgett, E A; Wiegel, B; Hertel, N E

    2010-12-01

    In a recent work, we constructed modular multisphere system which expands upon the design of an existing, commercially available Bonner sphere system by adding concentric shells of copper, tungsten, or lead. Our modular multisphere system is referred to as the Bonner Sphere Extension (BSE). The BSE was tested in a high energy neutron beam (thermal to 800 MeV) at Los Alamos Neutron Science Center and provided improvement in the measurement of the neutron spectrum in the energy regions above 20 MeV when compared to the standard BSS (Burgett, 2008 and Howell et al., 2009).However, when the initial test of the system was carried-out at LANSCE, the BSE had not yet been calibrated. Therefore the objective of the present study was to perform calibration measurements. These calibration measurements were carried out using monoenergetic neutron ISO 8529-1 reference beams at the Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany. The following monoenergetic reference beams were used for these experiments: 14.8 MeV, 1.2 MeV, 565 keV, and 144 keV. Response functions for the BSE were calculated using the Monte Carlo N-Particle Code, eXtended (MCNPX). The percent difference between the measured and calculated responses was calculated for each sphere and energy. The difference between measured and calculated responses for individual spheres ranged between 7.9 % and 16.7 % and the arithmetic mean for all spheres was (10.9 ± 1.8) %. These sphere specific correction factors will be applied for all future measurements carried-out with the BSE.

  3. Measurements and Monte Carlo calculations with the extended-range Bonner sphere spectrometer at high-energy mixed fields

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00406842; Bay, Aurelio; Silari, Marco; Aroua, Abbas

    The use of spectrometry to provide information for neutron radiation protection has become an increasingly important activity over recent years. The need for spectral data arises because neither area survey instruments nor personal dosimeters give the correct dose equivalent results at all neutron energies. It is important therefore to know the spectra of the fields in which these devices are used. One of the systems most commonly employed in neutron spectrometry and dosimetry is the Bonner Sphere Spectrometers (BSS). The extended- range BSS that was used for this work, consists of 7 spheres with an overall response to neutrons up to 2 GeV. A 3He detector is used as a thermal counter in the centre of each sphere. In the context of this thesis the BSS was calibrated in monoenergetic neutron fields at low and intermediate energies. It was also used for measurements in several high energy mixed fields. These measurements have led to the calculation of neutron yields and spectral fluences from unshielded targets....

  4. Reconstruction of neutron spectra using neural networks starting from the Bonner spheres spectrometric system; Reconstruccion de espectros de neutrones usando redes neuronales a partir del sistema espectrometrico de esferas de Bonner

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz R, J.M.; Martinez B, M.R.; Arteaga A, T.; Vega C, H.R.; Hernandez D, V.M.; Manzanares A, E. [Universidad Autonoma de Zacatecas, A.P. 336, 98000 Zacatecas (Mexico)

    2005-07-01

    The artificial neural networks (RN) have been used successfully to solve a wide variety of problems. However to determine an appropriate set of values of the structural parameters and of learning of these, it continues being even a difficult task. Contrary to previous works, here a set of neural networks is designed to reconstruct neutron spectra starting from the counting rates coming from the detectors of the Bonner spheres system, using a systematic and experimental strategy for the robust design of multilayer neural networks of the feed forward type of inverse propagation. The robust design is formulated as a design problem of Taguchi parameters. It was selected a set of 53 neutron spectra, compiled by the International Atomic Energy Agency, the counting rates were calculated that would take place in a Bonner spheres system, the set was arranged according to the wave form of those spectra. With these data and applying the Taguchi methodology to determine the best parameters of the network topology, it was trained and it proved the same one with the spectra. (Author)

  5. Measurements of H*(10) in reference neutron fields using Bonner sphere spectrometry and LET spectrometry

    CERN Document Server

    Golnik, N; Králik, M

    2002-01-01

    A Bonner sphere spectrometer and the REM-2 recombination chamber were used for inter-comparison measurements of the neutron component of ambient dose equivalent, H sub n *(10) in reference neutron fields. The sup 2 sup 4 sup 1 Am-Be and sup 2 sup 5 sup 2 Cf neutron sources were exposed either free-in-air or placed in iron or paraffin filters. The REM-2 recombination chamber was used as a LET spectrometer. The agreement of H sub n *(10) values measured with both the methods was within experimental uncertainties of few percent. The determined neutron spectra were used for calculations of the REM-2 chamber response to H*(10).

  6. Reprint of The improvement of the energy resolution in epi-thermal neutron region of Bonner sphere using boric acid water solution moderator.

    Science.gov (United States)

    Ueda, H; Tanaka, H; Sakurai, Y

    2015-12-01

    Bonner sphere is useful to evaluate the neutron spectrum in detail. We are improving the energy resolution in epi-thermal neutron region of Bonner sphere, using boric acid water solution as a moderator. Its response function peak is narrower than that for polyethylene moderator and the improvement of the resolution is expected. The resolutions between polyethylene moderator and boric acid water solution moderator were compared by simulation calculation. Also the influence in the uncertainty of Bonner sphere configuration to spectrum estimation was simulated.

  7. The improvement of the energy resolution in epi-thermal neutron region of Bonner sphere using boric acid water solution moderator.

    Science.gov (United States)

    Ueda, H; Tanaka, H; Sakurai, Y

    2015-10-01

    Bonner sphere is useful to evaluate the neutron spectrum in detail. We are improving the energy resolution in epi-thermal neutron region of Bonner sphere, using boric acid water solution as a moderator. Its response function peak is narrower than that for polyethylene moderator and the improvement of the resolution is expected. The resolutions between polyethylene moderator and boric acid water solution moderator were compared by simulation calculation. Also the influence in the uncertainty of Bonner sphere configuration to spectrum estimation was simulated.

  8. Neutron spectrum measurements at a radial beam port of the NUR research reactor using a Bonner spheres spectrometer.

    Science.gov (United States)

    Mazrou, H; Nedjar, A; Seguini, T

    2016-08-01

    This paper describes the measurement campaign held around the neutron radiography (NR) facility of the Algerian 1MW NUR research reactor. The main objective of this work is to characterize accurately the neutron beam provided at one of the radial channels of the NUR research reactor taking benefit of the acquired CRNA Bonner spheres spectrometer (BSS). The specific objective was to improve the image quality of the NR facility. The spectrometric system in use is based on a central spherical (3)He thermal neutron proportional counter combined with high density polyethylene spheres of different diameters ranging from 3 to 12in. This counting system has good gamma ray discrimination and is able to cover an energy range from thermal to 20MeV. The measurements were performed at the sample distance of 0.6m from the beam port and at a height of 1.2m from the facility floor. During the BSS measurements, the reactor was operating at low power (100W) to avoid large dead times, pulse pileup and high level radiation exposures, in particular, during spheres handling. Thereafter, the neutron spectrum at the sample position was unfolded by means of GRAVEL and MAXED computer codes. The thermal, epithermal and fast neutron fluxes, the total neutron flux, the mean energy and the Cadmium ratio (RCd) were provided. A sensitivity analysis was performed taking into account various defaults spectra and ultimately a different response functions in the unfolding procedure. Overall, from the obtained results it reveals, unexpectedly, that the measured neutron spectrum at the sample position of the neutron radiography of the NUR reactor is being harder with a predominance of fast neutrons (>100keV) by about 60%. Finally, those results were compared to previous and more recent measurements obtained by activation foils detectors. The agreement was fairly good highlighting thereby the consistency of our findings.

  9. Optimization of the architecture of a neural network in neutron spectrometry to reduce the number of Bonner spheres; Optimizacion de la arquitectura de una red neuronal en espectrometria de neutrones para reducer el numero de esferas Bonner

    Energy Technology Data Exchange (ETDEWEB)

    Leon P, A. A.; Martinez B, M. R.; Hernandez P, C. F.; Espinoza G, J. G.; Castaneda M, V. H.; Solis S, L. O.; Castaneda M, R.; Ortiz R, J. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Av. Ramon Lopez Velarde 801, Col. Centro, 98000 Zacatecas, Zac. (Mexico); Mendez V, R. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Laboratorio de Patrones Neutronicos, Av. Complutense 22, 28040 Madrid (Spain); Gallego, E. [Universidad Politecnica de Madrid, Departamento de Ingenieria Nuclear, ETSI Industriales, Jose Gutierrez Abascal 2, 28006 Madrid (Spain); De Sousa L, M. A. [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Pampulha, Belo Horizonte, Minas Gerais (Brazil)

    2016-10-15

    The neutron spectrometry is an experimental process for determining the energy distribution called the Spectrum. Among the methods available for neutron spectrometry, one can mention the Bonner Sphere Spectrometric System as one of the most used, consisting of a detector placed in the center of a set of polyethylene spheres whose diameters range from 2 to 18 inches, however has some disadvantages such as the long periods of time to perform the measurements, the weight and the spheres number that vary according to the system. From this, alternative methods such as artificial neural networks are proposed. For this project neural networks of reverse propagation were used with the methodology of robust design of artificial neural networks, with the aid of a computational tool that maximizes the performance, making the time used for the training s of the network is the smallest possible and thus gets the orthogonal fixes quickly to determine the best network topology. The counting rates of a spectrometric system with 7 spheres, 2 spheres and one sphere of 5 and 8 inches were used. This methodology seeks to reduce the work used as in the spectrometric system formed by a greater number of spheres, since to enter less data in the counting rates to obtain the spectra with 60 energy levels saves time and space, because at having a smaller number of spheres its portability is easier to move from one place to another, for this we performed several experiments with different errors until we reached the optimal error so that the topology of the network was appropriate and find the best design parameters. A statistical software JMP was also used to obtain the best topologies and thus to retrain obtaining its best and worst spectra, in order to determine if the reduction is possible. (Author)

  10. Neutron measurements in the Vandellòs II nuclear power plant with a Bonner sphere system.

    Science.gov (United States)

    Fernández, F; Bakali, M; Tomás, M; Muller, H; Pochat, J L

    2004-01-01

    In some Spanish nuclear power plants of pressurised water reactor (PWR) type, albedo thermoluminescence dosemeters are used for personal dosimetry while survey meters, based on a thermal-neutron detector inside a cylindrical or spherical moderator, are used for dose rate assessment in routine monitoring. The response of both systems is highly dependent on the energy of the existing neutron fields. They are usually calibrated by means of ISO neutron sources with energy distributions quite different from those encountered at these installations. Spectrometric measurements with a Bonner sphere system (BSS) allow us to determine the reference dosimetric values. The UAB group, under request from the National Coordinated Research Action, was in charge of characterising the neutron fields and evaluating the response of personal dosemeters at several measurement points inside the containment building of the Catalan Nuclear Power Plant Vandellòs II. The neutron fields were characterised at five places using the UAB-BSS and a home made unfolding code called MITOM. The results obtained confirm the presence of low-energy components in the neutron field in most of the selected points. Moreover, we have found no influence of the nuclear fuel burning on the shape of the spectrum.

  11. NSDann2BS, a neutron spectrum unfolding code based on neural networks technology and two bonner spheres

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz-Rodriguez, J. M.; Reyes Alfaro, A.; Reyes Haro, A.; Solis Sanches, L. O.; Miranda, R. Castaneda; Cervantes Viramontes, J. M. [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica. Av. Ramon Lopez Velarde 801. Col. Centro Zacatecas, Zac (Mexico); Vega-Carrillo, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica. Av. Ramon Lopez Velarde 801. Col. Centro Zacatecas, Zac., Mexico. and Unidad Academica de Estudios Nucleares. C. Cip (Mexico)

    2013-07-03

    In this work a neutron spectrum unfolding code, based on artificial intelligence technology is presented. The code called ''Neutron Spectrometry and Dosimetry with Artificial Neural Networks and two Bonner spheres'', (NSDann2BS), was designed in a graphical user interface under the LabVIEW programming environment. The main features of this code are to use an embedded artificial neural network architecture optimized with the ''Robust design of artificial neural networks methodology'' and to use two Bonner spheres as the only piece of information. In order to build the code here presented, once the net topology was optimized and properly trained, knowledge stored at synaptic weights was extracted and using a graphical framework build on the LabVIEW programming environment, the NSDann2BS code was designed. This code is friendly, intuitive and easy to use for the end user. The code is freely available upon request to authors. To demonstrate the use of the neural net embedded in the NSDann2BS code, the rate counts of {sup 252}Cf, {sup 241}AmBe and {sup 239}PuBe neutron sources measured with a Bonner spheres system.

  12. First test of SP{sup 2}: A novel active neutron spectrometer condensing the functionality of Bonner spheres in a single moderator

    Energy Technology Data Exchange (ETDEWEB)

    Bedogni, R. [INFN-LNF Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy); Bortot, D. [Politecnico di Milano—Dipartimento di Energia, Via Ponzio 34/3, 20133 Milano (Italy); INFN—sezione di Milano, Via Celoria 16, 20133 Milano (Italy); Buonomo, B.; Esposito, A. [INFN-LNF Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy); Gómez-Ros, J.M. [INFN-LNF Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy); CIEMAT, Av. Complutense 40, 28040 Madrid (Spain); Introini, M.V.; Lorenzoli, M.; Pola, A. [Politecnico di Milano—Dipartimento di Energia, Via Ponzio 34/3, 20133 Milano (Italy); INFN—sezione di Milano, Via Celoria 16, 20133 Milano (Italy); Sacco, D. [INFN-LNF Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy); INAIL—DPIA Via di Fontana Candida n.1, 00040 Monteporzio C. (Italy)

    2014-12-11

    The NESCOFI@BTF (2011–2013) international collaboration was established to develop realtime neutron spectrometers to simultaneously cover all energy components of neutron fields, from thermal up to hundreds MeV. This communication concerns a new spherical spectrometer, called SP^2, which condenses the functionality of an Extended Range Bonner Sphere Spectrometer (ERBSS) into a single moderator embedding multiple active thermal neutron detectors. The possibility of achieving the complete spectrometric information in a single exposure constitutes a great advantage compared to the ERBSS. The first experimental test of the instrument, performed with a reference 241Am–Be source in different irradiation geometries, is described. The agreement between observed and simulated response is satisfactory for all tested geometries.

  13. Iterative code for the reconstruction of the neutrons spectrum using the Bonner spheres; Codigo iterativo para la reconstruccion del espectro de neutrones usando las esferas Bonner

    Energy Technology Data Exchange (ETDEWEB)

    Reyes H, A.; Ortiz R, J. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2012-10-15

    The neutrons are the particles more difficult of detecting for their intrinsic nature. The absence of the neutrons charge makes that an interaction exists with the matter in a different way. The term radiation spectrometry can use to describe the measurement of the intensity of a radiation field with regard to the energy. The intensity distribution with relationship to the energy is commonly known as spectrum. A method to know the neutrons spectrum in the radiation fields to those that people are exposed is the use of the known system as spectrometry system of Bonner spheres, being the more used for the purposes of the radiological protection. The current interest in the electrons spectrometry has stimulated the development of several procedures to carry out the reconstruction of the spectra. During the last decades new codes have been developed such as BUNKIUT, Bums, Fruit, UMG, etc., however, these methods still present several inconveniences as the complexity in their use, the necessity of an expert user and a very near initial spectrum to the spectrum that is wanted to obtain. To solve the mentioned problems it was development the program NSDUAZ (Neutron Spectrometry and Dosimetry from Autonomous University of Zacatecas). The objective of the present work is to prove and to validate the code before mentioned making an analysis of likeness and differences and of advantages and disadvantages with relationship to the codes used at the present time. (Author)

  14. Measurement of the neutron fields produced by a 62 MeV proton beam on a PMMA phantom using extended range Bonner sphere spectrometers

    Science.gov (United States)

    Amgarou, K.; Bedogni, R.; Domingo, C.; Esposito, A.; Gentile, A.; Carinci, G.; Russo, S.

    2011-10-01

    The experimental characterization of the neutron fields produced as parasitic effect in medical accelerators is assuming an increased importance for either the patient protection or the facility design aspects. Medical accelerators are diverse in terms of particle type (electrons or hadrons) and energy, but the radiation fields around them have in common (provided that a given threshold energy is reached) the presence of neutrons with energy span over several orders of magnitude. Due to the large variability of neutron energy, field or dosimetry measurements in these workplaces are very complex, and in general, cannot be performed with ready-to-use commercial instruments. In spite of its poor energy resolution, the Bonner Sphere Spectrometer (BSS) is the only instrument able to simultaneously determine all spectral components in such workplaces. The energy range of this instrument is limited to EFisica Nucleare—Laboratori Nazionali di Frascati) were exposed to characterize the "forward" and "sideward" proton-induced neutron fields. The use of two ERBSS characterized by different set of spheres, central detectors, and independently established and calibrated, is important for guaranteeing the robustness of the measured spectra and estimating their overall uncertainties.

  15. Measurement of neutron spectra generated by a 62 AMeV carbon-ion beam on a PMMA phantom using extended range Bonner sphere spectrometers

    Science.gov (United States)

    Bedogni, R.; Amgarou, K.; Domingo, C.; Russo, S.; Cirrone, G. A. P.; Pelliccioni, M.; Esposito, A.; Pola, A.; Introini, M. V.; Gentile, A.

    2012-07-01

    Neutrons constitute an important component of the radiation environment in hadron therapy accelerators. Their energy distribution may span from thermal up to hundred of MeV. The characterization of these fields in terms of dosimetric or spectrometric quantities is crucial for either the patient protection or the facility design aspects. To date, the Extended Range Bonner Sphere Spectrometer (ERBSS) is the only instrument able to simultaneously determine all spectral components in such workplaces. With the aim of providing useful data to the scientific community involved in neutron measurements at hadron therapy facilities, a measurement campaign was carried out at the Centro di AdroTerapia e Applicazioni Nucleari Avanzate (CATANA) of INFN-LNS (Laboratori Nazionali del Sud), where a 62 AMeV carbon ion is available. The beam was directed towards a PMMA phantom, simulating the patient, and two neutron measurement points were established at 0° and 90° with respect to the beam-line. The ERBSSs of UAB (Universidad Autónoma de Barcelona-Grup de Física de les Radiacions) and INFN (Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali di Frascati) were used to measure the resulting neutron fields. The two ERBSSs use different detectors and sphere diameters, and have been independently calibrated. The FRUIT code was used to unfold the results.

  16. Performance Evaluation of List Sphere Detector

    Institute of Scientific and Technical Information of China (English)

    HE Xiang; LUO Han-wen; YI Yang

    2005-01-01

    A list sphere detector can use a smaller list than commonly believed by employing an appropriate soft output approximation method. Its effect on the "quality" of detector's soft output value is evaluated by measuringmutual information under ergodic channel. The result shows a length 40 list is adequate for a 4 × 4 16QAM MIMO system without system-level iteration. For the ergodic channel, the gain of a sphere detector over the linear MMSE detector is dependent on channel coding rate, which answers an important question when sphere detector should be used in system level design. All these theoretical results are then verified by Monte Carlo simulation.

  17. Neutron field measurements of the CRNA OB26 irradiator using a Bonner sphere spectrometer for radiation protection purposes.

    Science.gov (United States)

    Mazrou, H; Allab, M

    2012-08-01

    The present work deals with the Bonner sphere spectrometer (BSS) measurements performed, to support the authors' Monte-Carlo calculations, to estimate accurately the main characteristics of the neutron field of the (241)Am-Be-based OB26 irradiator acquired for radiation protection purposes by the Nuclear Research Centre of Algiers. The measurements were performed at a reference irradiation position selected at 150 cm from the geometrical centre of the neutron source. The spectrometric system in use is based on a central spherical (3)He thermal neutron proportional counter. The response matrix of the present spectrometer has been taken to be similar to the original Physikalisch-Technische Bundesanstalt (PTB) (Braunschweig, Germany) BSS's response matrix, with a five bins per decade energy group structure, as there is no significant difference in the BSS's physical characteristics. Thereafter, the authors' BSS measurements were used together with MCNP5 results to unfold the neutron spectrum by means of MAXED and GRAVEL computer codes from the U.M.G. 3.3 package, developed at PTB. Besides, sensitivity analysis has been performed to test the consistency of the unfolding procedure. It reveals that no significant discrepancy was observed in the total neutron fluence and total ambient dose values following the perturbation of some pertinent unfolding parameters except for the case where a 10 bins energy structure was assumed for the guess spectrum. In this latter case, a 5 % difference was observed in the ambient dose equivalent compared with the reference case. Finally, a comparative study performed between different counting systems together with MCNP5 and predictive formulas results shows that they were globally satisfactory, highlighting thereby the relevance of the unfolding procedure and the reliability of the obtained results.

  18. Characterization of extended range Bonner Sphere Spectrometers in the CERF high-energy broad neutron field at CERN

    Science.gov (United States)

    Agosteo, S.; Bedogni, R.; Caresana, M.; Charitonidis, N.; Chiti, M.; Esposito, A.; Ferrarini, M.; Severino, C.; Silari, M.

    2012-12-01

    The accurate determination of the ambient dose equivalent in the mixed neutron-photon fields encountered around high-energy particle accelerators still represents a challenging task. The main complexity arises from the extreme variability of the neutron energy, which spans over 10 orders of magnitude or more. Operational survey instruments, which response function attempts to mimic the fluence-to-ambient dose equivalent conversion coefficient up to GeV neutrons, are available on the market, but their response is not fully reliable over the entire energy range. Extended range rem counters (ERRC) do not require the exact knowledge of the energy distribution of the neutron field and the calibration can be done with a source spectrum. If the actual neutron field has an energy distribution different from the calibration spectrum, the measurement is affected by an added uncertainty related to the partial overlap of the fluence-to-ambient dose equivalent conversion curve and the response function. For this reason their operational use should always be preceded by an "in-field" calibration, i.e. a calibration made against a reference instrument exposed in the same field where the survey-meter will be employed. In practice the extended-range Bonner Sphere Spectrometer (ERBSS) is the only device which can serve as reference instrument in these fields, because of its wide energy range and the possibility to assess the neutron fluence and the ambient dose equivalent (H*(10)) values with the appropriate accuracy. Nevertheless, the experience gained by a number of experimental groups suggests that mandatory conditions for obtaining accurate results in workplaces are: (1) the use of a well-established response matrix, thus implying validation campaigns in reference monochromatic neutrons fields, (2) the expert and critical use of suitable unfolding codes, and (3) the performance test of the whole system (experimental set-up, elaboration and unfolding procedures) in a well

  19. Neutron spectrometry and dosimetry by means of Bonner spheres system and artificial neural networks applying robust design of artificial neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Martinez B, M.R.; Ortiz R, J.M.; Vega C, H.R. [UAZ, Av. Ramon Lopez Velarde No. 801, 98000 Zacatecas (Mexico)

    2006-07-01

    An Artificial Neural Network has been designed, trained and tested to unfold neutron spectra and simultaneously to calculate equivalent doses. A set of 187 neutron spectra compiled by the International Atomic Energy Agency and 13 equivalent doses were used in the artificial neural network designed, trained and tested. In order to design the neural network was used the robust design of artificial neural networks methodology, which assures that the quality of the neural networks takes into account from the design stage. Unless previous works, here, for first time a group of neural networks were designed and trained to unfold 187 neutron spectra and at the same time to calculate 13 equivalent doses, starting from the count rates coming from the Bonner spheres system by using a systematic and experimental strategy. (Author)

  20. Measurements of neutron energy spectra from 7Li(p,n)7Be reaction with Bonner sphere spectrometer, Nested Neutron Spectrometer and ROSPEC.

    Science.gov (United States)

    Atanackovic, J; Matysiak, W; Witharana, S; Dubeau, J; Waker, A J

    2014-10-01

    Neutron spectrometry measurements were carried out at the McMaster Accelerator Laboratory (MAL), which is equipped with a 3-MV Van de Graaff-type accelerator. Protons were accelerated onto a thick natural lithium target inducing the (7)Li(p,n)(7)Be threshold reaction. Depending on the proton energy, slightly different poly-energetic neutron fields were produced. Neutron spectra were measured at two incident proton energies: 2.15 and 2.24 MeV, which produced poly-energetic neutrons with maximum kinetic energies of 401 and 511 keV, respectively. Measurements were performed at a distance of 1.5 m from the target in the forward direction with three different instruments: Bonner sphere spectrometer, Nested Neutron Spectrometer and ROtational proton recoil SPECtrometer.

  1. Comparison of Bonner sphere responses calculated by different Monte Carlo codes at energies between 1 MeV and 1 GeV – Potential impact on neutron dosimetry at energies higher than 20 MeV

    CERN Document Server

    Rühm, W; Pioch, C; Agosteo, S; Endo, A; Ferrarini, M; Rakhno, I; Rollet, S; Satoh, D; Vincke, H

    2014-01-01

    Bonner Spheres Spectrometry in its high-energy extended version is an established method to quantify neutrons at a wide energy range from several meV up to more than 1 GeV. In order to allow for quantitative measurements, the responses of the various spheres used in a Bonner Sphere Spectrometer (BSS) are usually simulated by Monte Carlo (MC) codes over the neutron energy range of interest. Because above 20 MeV experimental cross section data are scarce, intra-nuclear cascade (INC) and evaporation models are applied in these MC codes. It was suspected that this lack of data above 20 MeV may translate to differences in simulated BSS response functions depending on the MC code and nuclear models used, which in turn may add to the uncertainty involved in Bonner Sphere Spectrometry, in particular for neutron energies above 20 MeV. In order to investigate this issue in a systematic way, EURADOS (European Radiation Dosimetry Group) initiated an exercise where six groups having experience in neutron transport calcula...

  2. Development of a Geant4 application to characterise a prototype neutron detector based on three orthogonal (3)He tubes inside an HDPE sphere.

    Science.gov (United States)

    Gracanin, V; Guatelli, S; Prokopovich, D; Rosenfeld, A B; Berry, A

    2017-01-01

    The Bonner Sphere Spectrometer (BSS) system is a well-established technique for neutron dosimetry that involves detection of thermal neutrons within a range of hydrogenous moderators. BSS detectors are often used to perform neutron field surveys in order to determine the ambient dose equivalent H*(10) and estimate health risk to personnel. There is a potential limitation of existing neutron survey techniques, since some detectors do not consider the direction of the neutron field, which can result in overly conservative estimates of dose in neutron fields. This paper shows the development of a Geant4 simulation application to characterise a prototype neutron detector based on three orthogonal (3)He tubes inside a single HDPE sphere built at the Australian Nuclear Science and Technology Organisation (ANSTO). The Geant4 simulation has been validated with respect to experimental measurements performed with an Am-Be source.

  3. Neutron spectrometry and dosimetry study at two research nuclear reactors using Bonner sphere spectrometer (BSS), rotational spectrometer (ROSPEC) and cylindrical nested neutron spectrometer (NNS).

    Science.gov (United States)

    Atanackovic, J; Matysiak, W; Hakmana Witharana, S S; Aslam, I; Dubeau, J; Waker, A J

    2013-01-01

    Neutron spectrometry and subsequent dosimetry measurements were undertaken at the McMaster Nuclear Reactor (MNR) and AECL Chalk River National Research Universal (NRU) Reactor. The instruments used were a Bonner sphere spectrometer (BSS), a cylindrical nested neutron spectrometer (NNS) and a commercially available rotational proton recoil spectrometer. The purposes of these measurements were to: (1) compare the results obtained by three different neutron measuring instruments and (2) quantify neutron fields of interest. The results showed vastly different neutron spectral shapes for the two different reactors. This is not surprising, considering the type of the reactors and the locations where the measurements were performed. MNR is a heavily shielded light water moderated reactor, while NRU is a heavy water moderated reactor. The measurements at MNR were taken at the base of the reactor pool, where a large amount of water and concrete shielding is present, while measurements at NRU were taken at the top of the reactor (TOR) plate, where there is only heavy water and steel between the reactor core and the measuring instrument. As a result, a large component of the thermal neutron fluence was measured at MNR, while a negligible amount of thermal neutrons was measured at NRU. The neutron ambient dose rates at NRU TOR were measured to be between 0.03 and 0.06 mSv h⁻¹, while at MNR, these values were between 0.07 and 2.8 mSv h⁻¹ inside the beam port and <0.2 mSv h⁻¹ between two operating beam ports. The conservative uncertainty of these values is 15 %. The conservative uncertainty of the measured integral neutron fluence is 5 %. It was also found that BSS over-responded slightly due to a non-calibrated response matrix.

  4. A NEW COMPLEX SPHERE DETECTOR WITH SE ENUMERATION

    Institute of Scientific and Technical Information of China (English)

    Yao Heng; Jian Haifang; Shi Yin

    2012-01-01

    Multiple-Input Multiple-Output (MIMO) techniques are promising in wireless communication systems for its high spectral efficiency.Sphere Detector (SD) is favoured in MIMO detection to achieve Maximum-Likelihood (ML) performance.In this paper,we proposed a new SD method for MIMO-Orthogonal Frequency Division Multiplexing (OFDM) systems based on IEEE802.11n,which uses Singular Value Decomposition (SVD) in complex domain to reduce the computation complexity.Furthermore,a new Schnorr-Euchner (SE) enumeration algorithm is also discussed in detail.The computer simulation result shows that the computational complexity and the number of visited nodes can be reduced significantly compared with conventional SD detectors with the same Bit Error Rate (BER) performance.

  5. A wideband and sensitive GW detector for kHz frequencies: the dual sphere

    CERN Document Server

    Conti, L; Bonaldi, M; Cerdonio, M; Falferi, P; Heidmann, A; Lobo, J A; Marin, F; Ortolan, A; Pinard, M; Prodi, G A; Taffarello, L; Vitale, S; Zendri, J P

    2002-01-01

    We discuss the new concept of a sensitive and wide-band detector, consisting of a solid sphere nested inside a hollow one: the dual sphere. The advantage is that it would be possible to keep both the omni-directionality and high sensitivity of the spherical geometry without giving up the wide band. In the few kHz range the dual sphere would be complementary to 'advanced' interferometers. We also discuss the main technological and scientific challenges that the construction of such a system poses, particularly regarding material choice, fabrication, cooling, suspension and readout.

  6. Application-Specific Instruction Set Processor Implementation of List Sphere Detector

    Directory of Open Access Journals (Sweden)

    Salmela Perttu

    2007-01-01

    Full Text Available Multiple-input multiple-output (MIMO technology enables higher transmission capacity without additional frequency spectrum and is becoming a part of many wireless system standards. Sphere detection has been introduced in MIMO systems to achieve maximum likelihood (ML or near-ML estimation with reduced complexity. This paper reviews related work on sphere detector implementations and presents an application-specific instruction set processor (ASIP implementation of K-best list sphere detector (LSD using transport triggered architecture (TTA. The implementation is based on using memory and heap data structure for symbol vector sorting. The design space is explored by presenting several variations of the implementation and comparing them with each other in terms of their latencies and hardware complexities. An early proposal for a parallelized architecture with a decoding throughput of approximately 5.3 Mbps is presented

  7. Comparison of measurements with active and passive Bonner sphere spectrometers

    CERN Document Server

    Hajek, M; Schoner, W; Vana, N

    2000-01-01

    Because of its high biological efficiency, neutron radiation can be a serious source-and not only around accelerators and nuclear fusion reactors. Roughly half of the radiation exposure of aircrew members is caused by cosmic ray-induced neutrons in a wide energy range. Therefore, following the International Commission on Radiological Protection's recommendations, aircrew are treated as occupationally exposed workers by a recent directive of the European Council, which implies various safety precautions including the dosimetric surveillance. The accurate assessment of operational and limiting quantities such as ambient dose equivalent H*(10) and effective dose E requires the knowledge of the neutron energy spectrum. The CERN-CEC neutron reference field has been designed to resemble the neutron spectrum at an average subsonic aviation altitude. Therefore, it provides an excellent calibration facility for all instruments with intended applications in this field. The stray radiation field is created by a mixed be...

  8. Thick activation detectors for neutron spectrometry using different unfolding methods: sensitivity analysis and dose calculation

    Energy Technology Data Exchange (ETDEWEB)

    Medkour Ishak-Boushaki, Ghania, E-mail: gmedkour@yahoo.com [Laboratoire SNIRM-Faculte de Physique, Universite des Sciences et de la Technologie Houari Boumediene, BP 32 El-Alia BabEzzouar, Algiers (Algeria); Boukeffoussa, Khelifa [Laboratoire SNIRM-Faculte de Physique, Universite des Sciences et de la Technologie Houari Boumediene, BP 32 El-Alia BabEzzouar, Algiers (Algeria); Idiri, Zahir [Centre de Recherche Nucleaire d' Alger, 02 Boulevard Frantz-Fanon, BP 399, Algiers (Algeria); Allab, Malika [Laboratoire SNIRM-Faculte de Physique, Universite des Sciences et de la Technologie Houari Boumediene, BP 32 El-Alia BabEzzouar, Algiers (Algeria)

    2012-03-15

    This paper discusses the use of threshold detectors of extended sizes for low intensity neutron fields' characterization. The detectors were tested by the measurement of the neutron spectrum of an {sup 241}Am-Be source. Integral quantities characterizing the neutron field, required for radiological protection, have been derived by unfolding the measured data. A good agreement is achieved between the obtained results and those deduced using Bonner spheres. In addition, a sensitivity analysis of the results to the deconvolution procedure is given. - Highlights: Black-Right-Pointing-Pointer Low intensity neutron fields' characterization using thick threshold detectors. Black-Right-Pointing-Pointer Low activity {sup 241}Am-Be neutron source spectrum measurement. Black-Right-Pointing-Pointer Integral quantities required for radiological protection have been derived. Black-Right-Pointing-Pointer The results are in good agreement with those deduced using Bonner spheres. Black-Right-Pointing-Pointer The results are not very sensitive to the chosen deconvolution procedure.

  9. Results on the primary CR spectrum and composition reconstructed with the SPHERE-2 detector

    CERN Document Server

    Antonov, R A; Bonvech, E A; Chernov, D V; Dzhatdoev, T A; Finger, Mir; Finger, Mix; Galkin, V I; Kabanova, N V; Petkun, A S; Podgrudkov, D A; Roganova, T M; Shaulov, S B; Sysoeva, T I

    2012-01-01

    First preliminary results of the balloon-borne experiment SPHERE-2 on the all-nuclei primary cosmic rays (PCR) spectrum and primary composition are presented. The primary spectrum in the energy range $10^{16}$--$5\\cdot10^{17}$ eV was reconstructed using characteristics of Vavilov-Cherenkov radiation of extensive air showers (EAS), reflected from a snow surface. Several sources of systematic uncertainties of the spectrum were analysed. A method for separation of the primary nuclei' groups based on the lateral distribution function' (LDF) steepness parameter is presented. Preliminary estimate of the mean light nuclei' fraction $f_{30-150}$ at energies $3\\cdot10^{16}$--$1.5\\cdot10^{17}$ eV was performed and yielded $f_{30-150}$= (21$\\pm$11)%.

  10. Efficient Sphere Detector Algorithm for Massive MIMO using GPU Hardware Accelerator

    KAUST Repository

    Arfaoui, Mohamed-Amine

    2016-06-01

    To further enhance the capacity of next generation wireless communication systems, massive MIMO has recently appeared as a necessary enabling technology to achieve high performance signal processing for large-scale multiple antennas. However, massive MIMO systems inevitably generate signal processing overheads, which translate into ever-increasing rate of complexity, and therefore, such system may not maintain the inherent real-time requirement of wireless systems. We redesign the non-linear sphere decoder method to increase the performance of the system, cast most memory-bound computations into compute-bound operations to reduce the overall complexity, and maintain the real-time processing thanks to the GPU computational power. We show a comprehensive complexity and performance analysis on an unprecedented MIMO system scale, which can ease the design phase toward simulating future massive MIMO wireless systems.

  11. Measuring Neutron Spectrum at MIT Research Reactor Utilizing He-3 Bonner Cylinder Approach with an Unfolding Analysis

    Science.gov (United States)

    Leder, Alexander; Ricochet Collaboration

    2016-03-01

    The Ricochet experiment seeks to measure Coherent (neutral-current) Elastic Neutrino-Nucleus Scattering (CENNS) using dark matter style detectors placed near a neutrino source, possibly the MIT research reactor (MITR), which offers a high continuous neutrino flux at high energies. Currently, Ricochet is characterizing the backgrounds at MITR. The main background is the neutrons emitted simultaneously from the core. To characterize this background, we wrapped a Bonner cylinder around a 3He thermal neutron detector, whose data was then unfolded to produce a neutron energy spectrum across several orders of magnitude. We discuss the resulting spectrum as well its implications for deploying Ricochet in the future.

  12. Neutron monitors and muon detectors for solar modulation studies: 2. $\\phi$ time series

    CERN Document Server

    Ghelfi, A; Cheminet, A; Derome, L; Hubert, G; Melot, F

    2016-01-01

    The level of solar modulation at different times (related to the solar activity) is a central question of solar and galactic cosmic-ray physics. In the first paper of this series, we have established a correspondence between the uncertainties on ground-based detectors count rates and the parameter $\\phi$ (modulation level in the force-field approximation) reconstructed from these count rates. In this second paper, we detail a procedure to obtain a reference $\\phi$ time series from neutron monitor data. We show that we can have an unbiased and accurate $\\phi$ reconstruction ($\\Delta\\phi/\\phi\\simeq 10\\%$). We also discuss the potential of Bonner spheres spectrometers and muon detectors to provide $\\phi$ time series. Two by-products of this calculation are updated $\\phi$ values for the cosmic-ray database and a web interface to retrieve and plot $\\phi$ from the 50's to today (\\url{http://lpsc.in2p3.fr/crdb}).

  13. An intercomparison of neutron dosimeters and detectors for in-containment dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Auman, L.E.; Miller, W.H.; Graham, C.C.; Stretch, C.D.; Welty, T.J.; West, L. Jr. (Department of Nuclear Engineering, University of Missouri, Columbia (United States))

    1992-02-01

    To improve the methodology for assessing neutron dose at Union Electric's Callaway Nuclear Power Plant, an intercomparison of neutron detectors and dosimeters was performed. Seven different neutron detectors and dosimeters were tested in four different neutron fields utilizing facilities at the Missouri University Research Reactor and at the Southwest Radiation Calibration Center at the University of Arkansas. In general, all results agree within a factor of 2 in predicting the neutron dose equivalent. It was concluded that measurements of dose in containment should utilize the Tissue-Equivalent Proportional Counter (TEPC), the Bonner-sphere system, and the proton recoil spectrometer to accurately assess the neutron dose. These data can then be used to provide correction factors for more traditionally used dosimeters in containment, such as thermoluminescent dosimeters and survey meters.

  14. Routh's sphere

    NARCIS (Netherlands)

    Cushman, R.

    2001-01-01

    In this paper we show that the integral map of Rouths sphere has monodromy when the sphere becomes gyroscopically unstable This uses the nonHamiltonian monodromy of Rouths sphere has center of mass not at its geometrical center and moment of inertia tensor with two equal principal moments of inerti

  15. Public Sphere

    DEFF Research Database (Denmark)

    Trenz, Hans-Jörg

    2015-01-01

    In modern societies, the public sphere represents the intermediary realm that supports the communication of opinions, the discovery of problems that need to be dealt with collectively, the channeling of these problems through the filter of the media and political institutions, and the realization...... of the collective will of the people in the act of democratic self-government. The concept of the public sphere is used across the fields of media and communication research, cultural studies and the humanities, the history of ideas, legal and constitutional studies as well as democracy studies. Historically......, public spheres have undergone structural transformations that were closely connected to the emergence of different mass media. More recently, they are subject to trends of transnationalization and digitalization in politics and society....

  16. Quasisymmetric Spheres

    Directory of Open Access Journals (Sweden)

    Vellis Vyron

    2016-03-01

    Full Text Available Let Ω be a planar Jordan domain and α > 0. We consider double-dome-like surfaces Σ(Ω, tα over Ω where the height of the surface over any point x ∈ Ωequals dist(x, ∂Ωα. We identify the necessary and sufficient conditions in terms of and α so that these surfaces are quasisymmetric to S2 and we show that Σ(Ω, tα is quasisymmetric to the unit sphere S2 if and only if it is linearly locally connected and Ahlfors 2-regular.

  17. First quantum correction to entropy of Vaidya-Bonner black holes due to arbitrary spin fields

    Institute of Scientific and Technical Information of China (English)

    高长军; 沈有根

    2002-01-01

    Using the improved brick-wall model, we have calculated the first quantum correction to the entropy of non-staticblack holes, Vaidya-Bonner black holes, due to the gravitational, electro-magnetic and neutrino fields. The result showsthat both bosonic entropy and fermionic entropy are exactly proportional to the area of the event horizon. Thus, theentropy-area law still holds in such a non-static case.

  18. Hawking radiation of charged Dirac particles in Vaidya-Bonner space-time

    Institute of Scientific and Technical Information of China (English)

    朱建阳; 张建华; 赵峥

    1995-01-01

    The dynamical properties of charged Dirac spinor particles in the Vaidya-Bonner space-time are investigated. The asymptotic solution to the radial part of the charged Dirac equation near the event horizon of the black hole is obtained. The Hawking temperature and the event horizon of the charged evaporating black hole, as well as the spectrum of the Hawking radiation of the Dirac particles, are exactly shown. Thereby, a new approach to the back-reaction of radiation from the non-stationary black holes is established.

  19. Status of the SPHERE experiment

    CERN Document Server

    Antonov, R A; Bonvech, E A; Chernov, D V; Dzhatdoev, T A; Finger, Mir; Finger, M; Galkin, V I; Kabanova, N N; Petkun, A S; Podgrudkov, D A; Roganova, T M; Shaulov, S B; Sysoeva, T I

    2012-01-01

    Here is presented the current state of the SPHERE-2 balloon-borne experiment. The detector is elevated up to 1 km above the snow surface and registers the reflected Vavilov-Cherenkov radiation from extensive air showers. This method has good sensitivity to the mass-composition of the primary cosmic rays due to its high resolution near the shower axis. The detector consists of a 1500 mm spherical mirror with a 109 PMT cluster in its focus. The electronics record a signal pulse profile in each PMT. In the last 2 years the detector was upgraded: time resolution of pulse registration was enhanced up to 12.5 ns, channel sensitivity was increased by a factor of 3, a new LED-based relative PMT calibration method was introduced, and new hardware and etc. was installed.

  20. The hydrocarbon sphere

    Energy Technology Data Exchange (ETDEWEB)

    Mandev, P.

    1984-01-01

    The hydrocarbon sphere is understood to be the area in which hydrocarbon compounds are available. It is believed that the lower boundary on the hydrocarbon sphere is most probably located at a depth where the predominant temperatures aid in the destruction of hydrocarbons (300 to 400 degrees centigrade). The upper limit on the hydrocarbon sphere obviously occurs at the earth's surface, where hydrocarbons oxidize to H20 and CO2. Within these ranges, the occurrence of the hydrocarbon sphere may vary from the first few hundred meters to 15 kilometers or more. The hydrocarbon sphere is divided into the external (mantle) sphere in which the primary gas, oil and solid hydrocarbon fields are located, and the internal (metamorphic) sphere containing primarily noncommercial accumulations of hydrocarbon gases and solid carbon containing compounds (anthraxilite, shungite, graphite, etc.) based on the nature and scale of hydrocarbon compound concentrations (natural gas, oil, maltha, asphalt, asphaltite, etc.).

  1. Measurements of thermal neutron fluence in the bunker of a cyclotron for PET isotope production; Medidas de fluencia de neutrones termicos en el bunker de un ciclotron de produccion de isotopos para PET

    Energy Technology Data Exchange (ETDEWEB)

    Mendez Villafane, R.; Sansoloni florit, F.; Lagares gonzalez, J. L.; Llop Roig, J.; Guerrero Araque, J. E.; Muniz Gutierrez, J. L.; Perez Morales, J. M.

    2011-07-01

    To measure the neutron spectrum has been used spectrometry system based on Bonner spheres with Au flakes as thermal neutron detector at its center while the results are still pending and will be analyzing another job.

  2. Jammed lattice sphere packings

    OpenAIRE

    Kallus, Yoav; Marcotte, Étienne; Torquato, Salvatore

    2013-01-01

    We generate and study an ensemble of isostatic jammed hard-sphere lattices. These lattices are obtained by compression of a periodic system with an adaptive unit cell containing a single sphere until the point of mechanical stability. We present detailed numerical data about the densities, pair correlations, force distributions, and structure factors of such lattices. We show that this model retains many of the crucial structural features of the classical hard-sphere model and propose it as a...

  3. DISE: directed sphere exclusion.

    Science.gov (United States)

    Gobbi, Alberto; Lee, Man-Ling

    2003-01-01

    The Sphere Exclusion algorithm is a well-known algorithm used to select diverse subsets from chemical-compound libraries or collections. It can be applied with any given distance measure between two structures. It is popular because of the intuitive geometrical interpretation of the method and its good performance on large data sets. This paper describes Directed Sphere Exclusion (DISE), a modification of the Sphere Exclusion algorithm, which retains all positive properties of the Sphere Exclusion algorithm but generates a more even distribution of the selected compounds in the chemical space. In addition, the computational requirement is significantly reduced, thus it can be applied to very large data sets.

  4. SPHERES National Lab Facility

    Science.gov (United States)

    Benavides, Jose

    2014-01-01

    SPHERES is a facility of the ISS National Laboratory with three IVA nano-satellites designed and delivered by MIT to research estimation, control, and autonomy algorithms. Since Fall 2010, The SPHERES system is now operationally supported and managed by NASA Ames Research Center (ARC). A SPHERES Program Office was established and is located at NASA Ames Research Center. The SPHERES Program Office coordinates all SPHERES related research and STEM activities on-board the International Space Station (ISS), as well as, current and future payload development. By working aboard ISS under crew supervision, it provides a risk tolerant Test-bed Environment for Distributed Satellite Free-flying Control Algorithms. If anything goes wrong, reset and try again! NASA has made the capability available to other U.S. government agencies, schools, commercial companies and students to expand the pool of ideas for how to test and use these bowling ball-sized droids. For many of the researchers, SPHERES offers the only opportunity to do affordable on-orbit characterization of their technology in the microgravity environment. Future utilization of SPHERES as a facility will grow its capabilities as a platform for science, technology development, and education.

  5. Experimental test of a newly developed single-moderator, multi-detector, directional neutron spectrometer in reference monochromatic fields from 144 keV to 16.5 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Bedogni, R., E-mail: roberto.bedogni@lnf.infn.it [INFN – LNF, via E. Fermi n. 40, 00044 Frascati (Roma) (Italy); Gómez-Ros, J.M. [INFN – LNF, via E. Fermi n. 40, 00044 Frascati (Roma) (Italy); CIEMAT, Av. Complutense 40, 28040 Madrid (Spain); Pola, A.; Bortot, D. [Politecnico di Milano, Dipartimento di Energia, via La Masa 34, 20156 Milano (Italy); INFN – Milano, Via Celoria 16, 20133 Milano (Italy); Gentile, A. [INFN – LNF, via E. Fermi n. 40, 00044 Frascati (Roma) (Italy); Introini, M.V. [Politecnico di Milano, Dipartimento di Energia, via La Masa 34, 20156 Milano (Italy); INFN – Milano, Via Celoria 16, 20133 Milano (Italy); Buonomo, B. [INFN – LNF, via E. Fermi n. 40, 00044 Frascati (Roma) (Italy); Lorenzoli, M. [Politecnico di Milano, Dipartimento di Energia, via La Masa 34, 20156 Milano (Italy); INFN – Milano, Via Celoria 16, 20133 Milano (Italy); Mazzitelli, M. [INFN – LNF, via E. Fermi n. 40, 00044 Frascati (Roma) (Italy); Sacco, D. [INFN – LNF, via E. Fermi n. 40, 00044 Frascati (Roma) (Italy); INAIL – DPIA, Via di Fontana Candida n.1, 00040 Monteporzio Catone (Italy)

    2015-05-11

    A new directional neutron spectrometer called CYSP (CYlindrical SPectrometer) was developed within the NESCOFI@BTF (2011–2013) collaboration. The device, composed by seven active thermal neutron detectors located along the axis of a cylindrical moderator, was designed to simultaneously respond from the thermal domain up to hundreds of MeV neutrons. The new spectrometer condenses the performance of the Bonner Sphere Spectrometer in a single moderator; thus requiring only one exposure to determine the whole spectrum. The CYSP response matrix, determined with MCNP, has been experimentally evaluated with monochromatic reference neutron fields from 144 keV to 16.5 MeV, plus a {sup 252}Cf source, available at NPL (Teddington, UK). The results of the experiment confirmed the correctness of the response matrix within an overall uncertainty of ±2.5%. The new active spectrometer CYSP offers an innovative option for real-time monitoring of directional neutron fields as those produced in neutron beam-lines.

  6. Bathymetric surveys of the Kootenai River near Bonners Ferry, Idaho, water year 2011

    Science.gov (United States)

    Fosness, Ryan L.

    2013-01-01

    In 2009, the Kootenai Tribe of Idaho released and implemented the Kootenai River Habitat Restoration Master Plan. This plan aimed to restore, enhance, and maintain the Kootenai River habitat and landscape to support and sustain habitat conditions for aquatic species and animal populations. In support of these restoration efforts, the U.S. Geological Survey, in cooperation with the Kootenai Tribe of Idaho, conducted high-resolution multibeam echosounder bathymetric surveys in May, June, and July 2011, as a baseline bathymetric monitoring survey on the Kootenai River near Bonners Ferry, Idaho. Three channel patterns or reaches exist in the study area—braided, meander, and a transitional zone connecting the braided and meander reaches. Bathymetric data were collected at three study areas in 2011 to provide: (1) surveys in unmapped portions of the meander reach; (2) monitoring of the presence and extent of sand along planned lines within a section of the meander reach; and (3) monitoring aggradation and degradation of the channel bed at specific cross sections within the braided reach and transitional zone. The bathymetric data will be used to update and verify flow models, calibrate and verify sediment transport modeling efforts, and aid in the biological assessment in support of the Kootenai River Habitat Restoration Master Plan. The data and planned lines for each study reach were produced in ASCII XYZ format supported by most geospatial software.

  7. Jammed lattice sphere packings.

    Science.gov (United States)

    Kallus, Yoav; Marcotte, Étienne; Torquato, Salvatore

    2013-12-01

    We generate and study an ensemble of isostatic jammed hard-sphere lattices. These lattices are obtained by compression of a periodic system with an adaptive unit cell containing a single sphere until the point of mechanical stability. We present detailed numerical data about the densities, pair correlations, force distributions, and structure factors of such lattices. We show that this model retains many of the crucial structural features of the classical hard-sphere model and propose it as a model for the jamming and glass transitions that enables exploration of much higher dimensions than are usually accessible.

  8. Affine Sphere Relativity

    Science.gov (United States)

    Minguzzi, E.

    2016-11-01

    We investigate spacetimes whose light cones could be anisotropic. We prove the equivalence of the structures: (a) Lorentz-Finsler manifold for which the mean Cartan torsion vanishes, (b) Lorentz-Finsler manifold for which the indicatrix (observer space) at each point is a convex hyperbolic affine sphere centered on the zero section, and (c) pair given by a spacetime volume and a sharp convex cone distribution. The equivalence suggests to describe (affine sphere) spacetimes with this structure, so that no algebraic-metrical concept enters the definition. As a result, this work shows how the metric features of spacetime emerge from elementary concepts such as measure and order. Non-relativistic spacetimes are obtained replacing proper spheres with improper spheres, so the distinction does not call for group theoretical elements. In physical terms, in affine sphere spacetimes the light cone distribution and the spacetime measure determine the motion of massive and massless particles (hence the dispersion relation). Furthermore, it is shown that, more generally, for Lorentz-Finsler theories non-differentiable at the cone, the lightlike geodesics and the transport of the particle momentum over them are well defined, though the curve parametrization could be undefined. Causality theory is also well behaved. Several results for affine sphere spacetimes are presented. Some results in Finsler geometry, for instance in the characterization of Randers spaces, are also included.

  9. AlphaSphere

    OpenAIRE

    Place, A.; Lacey, L.; Mitchell, T.

    2013-01-01

    The AlphaSphere is an electronic musical instrument featuring a series of tactile, pressure sensitive touch pads arranged in a spherical form. It is designed to offer a new playing style, while allowing for the expressive real-time modulation of sound available in electronic-based music. It is also designed to be programmable, enabling the flexibility to map a series of different notational arrangements to the pad-based interface.\\ud \\ud The AlphaSphere functions as an HID, MIDI and OSC devic...

  10. The Moyal Sphere

    CERN Document Server

    Eckstein, Michał; Wulkenhaar, Raimar

    2016-01-01

    We construct a family of constant curvature metrics on the Moyal plane and compute the Gauss-Bonnet term for each of them. They arise from the conformal rescaling of the metric in the orthonormal frame approach. We find a particular solution, which corresponds to the Fubini-Study metric and which equips the Moyal algebra with the geometry of a noncommutative sphere.

  11. The Moyal sphere

    Science.gov (United States)

    Eckstein, Michał; Sitarz, Andrzej; Wulkenhaar, Raimar

    2016-11-01

    We construct a family of constant curvature metrics on the Moyal plane and compute the Gauss-Bonnet term for each of them. They arise from the conformal rescaling of the metric in the orthonormal frame approach. We find a particular solution, which corresponds to the Fubini-Study metric and which equips the Moyal algebra with the geometry of a noncommutative sphere.

  12. Black carbon measurements using an integrating sphere

    Science.gov (United States)

    Hitzenberger, R.; Dusek, U.; Berner, A.

    1996-08-01

    An integrating sphere was used to determine the black carbon (BC) content of aerosol filter samples dissolved in chloroform (method originally described by Heintzenberg [1982]). The specific absorption coefficient Ba (equal to absorption per mass) of the samples was also measured using the sphere as an integrating detector for transmitted light. Comparing the Ba of ambient samples taken in Vienna, Austria, to the BC concentrations measured on the dissolved filters, a value of approximately 6 m2/g was found to be a reasonable value for the Ba of the black carbon found at the site. The size dependence of Ba of a nebulized suspension of soot was measured using a rotating impactor, and a reasonable agreement between measured and calculated values was found.

  13. ORGANIZATION IN CONTEMPORARY PUBLIC SPHERE

    Directory of Open Access Journals (Sweden)

    Rosemarie HAINES

    2013-12-01

    Full Text Available The critical analysis of Habermas’ Public Sphere Theory and the comparative undertaking to the current day enables us to assert that in contemporary society, public sphere is no longer a political public sphere, this dimension being completed by a societal dimension, the public sphere has extended and now we can talk about partial public spheres in an ever more commercial environment. The new rebuilding and communication technologies create a new type of public character: the visible sphere – non-located, non-dialogical and open. Information and communication are more and more involved in the restructuring of capitalism on an international scale and the reorganization of leadership and management systems. The reevaluation of the public sphere, public opinion, communication allows us to define public sphere according to the profound mutations from today’s democratic societies.

  14. Absolute multilateration between spheres

    Science.gov (United States)

    Muelaner, Jody; Wadsworth, William; Azini, Maria; Mullineux, Glen; Hughes, Ben; Reichold, Armin

    2017-04-01

    Environmental effects typically limit the accuracy of large scale coordinate measurements in applications such as aircraft production and particle accelerator alignment. This paper presents an initial design for a novel measurement technique with analysis and simulation showing that that it could overcome the environmental limitations to provide a step change in large scale coordinate measurement accuracy. Referred to as absolute multilateration between spheres (AMS), it involves using absolute distance interferometry to directly measure the distances between pairs of plain steel spheres. A large portion of each sphere remains accessible as a reference datum, while the laser path can be shielded from environmental disturbances. As a single scale bar this can provide accurate scale information to be used for instrument verification or network measurement scaling. Since spheres can be simultaneously measured from multiple directions, it also allows highly accurate multilateration-based coordinate measurements to act as a large scale datum structure for localized measurements, or to be integrated within assembly tooling, coordinate measurement machines or robotic machinery. Analysis and simulation show that AMS can be self-aligned to achieve a theoretical combined standard uncertainty for the independent uncertainties of an individual 1 m scale bar of approximately 0.49 µm. It is also shown that combined with a 1 µm m‑1 standard uncertainty in the central reference system this could result in coordinate standard uncertainty magnitudes of 42 µm over a slender 1 m by 20 m network. This would be a sufficient step change in accuracy to enable next generation aerospace structures with natural laminar flow and part-to-part interchangeability.

  15. VMware vSphere Design

    CERN Document Server

    Guthrie, Forbes; Saidel-Keesing, Maish

    2011-01-01

    The only book focused on designing VMware vSphere implementations.VMware vSphere is the most widely deployed virtualization platform today. Considered the most robust and sophisticated hypervisor product, vSphere is the de facto standard for businesses, both large and small. This book is the only one of its kind to concisely explain how to execute a successful vSphere architecture, tailored to meet your company's needs. Expert authors share with you the factors that shape the design of a vSphere implementation. Learn how to make the right design decisions for your environment.Explores the late

  16. Panoramic stereo sphere vision

    Science.gov (United States)

    Feng, Weijia; Zhang, Baofeng; Röning, Juha; Zong, Xiaoning; Yi, Tian

    2013-01-01

    Conventional stereo vision systems have a small field of view (FOV) which limits their usefulness for certain applications. While panorama vision is able to "see" in all directions of the observation space, scene depth information is missed because of the mapping from 3D reference coordinates to 2D panoramic image. In this paper, we present an innovative vision system which builds by a special combined fish-eye lenses module, and is capable of producing 3D coordinate information from the whole global observation space and acquiring no blind area 360°×360° panoramic image simultaneously just using single vision equipment with one time static shooting. It is called Panoramic Stereo Sphere Vision (PSSV). We proposed the geometric model, mathematic model and parameters calibration method in this paper. Specifically, video surveillance, robotic autonomous navigation, virtual reality, driving assistance, multiple maneuvering target tracking, automatic mapping of environments and attitude estimation are some of the applications which will benefit from PSSV.

  17. Tom Bonner Prize: Gamma-ray energy tracking array GRETINA and its early science results

    Science.gov (United States)

    Lee, I.-Yang

    2016-03-01

    Gamma-ray detector with good energy resolution has been one of the essential instruments for the study of nuclear structure. To push these studies toward the exotic nuclei near the particle stability line, we need detectors with higher peak efficiency and good peak-to-total ratio. In addition, radioactive ion beams needed for such studies are often produced by the projectile fragmentation method. They have high velocities, and detectors must provide adequate position resolution for accurate Doppler correction. To fulfill these requirements, the new concept of gamma ray energy tracking array was developed. GRETINA, with 1 π solid angle coverage, is the first implementation of this concept. It uses electrically segmented Ge crystals in a close packed geometry, fast digital electronics, and signal decomposition to determine the position and energy of the individual interaction points. Then the path of a gamma ray can be tracked using the angle-energy relation of the scattering process. GRETINA was completed at LBNL and started physics operation in 2012. It has been used at NSCL at MSU and ATLAS at ANL for a large number of experiments addressing diverse topics from nuclear structure to nuclear astrophysics. In this talk I will describe the concept of gamma-ray energy tracking and the technology developed for GRETINA. A few representative experiments showing the breadth of the science and the power of the instrument will be discussed. Finally the plan toward the full 4 π array GRETA will be presented.

  18. Haphazard Packing of Unequal Spheres

    Institute of Scientific and Technical Information of China (English)

    叶大年; 张金民

    1991-01-01

    Haphazard packing of equal and unequal spheres can be performed for the spheres of molecular sieve material with a density of 1.80.The packing of such spheres in air is equivalent to that of nat-ural grains in water.Packing concentrations of equal spheres have been obtained for different pac-king intensities.Unequal spheres can be regarded as equal ones in a wide range of diameter ratios,so far as the packing concentration is concerned.A threshold of diameter ratio exists at 0.70,be-low which the packing concentration is expected to increase.The variation curves of concentration vs.diameter ratio were established in the experiment.The result will help us to understand the process of sedimentation and the concentration of voids in sedimentary rocks.

  19. The Sphere Anemometer - A Fast Alternative to Cup Anemometry

    Science.gov (United States)

    Heißelmann, Hendrik; Hölling, Michael; Peinke, Joachim

    The main problem of cup anemometry is the different response time for increasing and decreasing wind velocities due to its moment of inertia. This results in an overestimation of wind speed under turbulent wind conditions, the so-called over-speeding. Additionally, routine calibrations are necessary due to the wear of bearings. Motivated by these problems the sphere anemometer, a new simple and robust sensor for wind velocity measurements without moving parts, was developed at the University of Oldenburg. In contrast to other known thrust-based sensors, the sphere anemometer uses the light pointer principle to detect the deflection of a bending tube caused by the drag force acting on a sphere mounted at its top. This technique allows the simultaneous determination of wind speed and direction via a two-dimensional position sensitive detector.

  20. Isentropic Spheres in General Relativity

    CERN Document Server

    Humi, Mayer

    2016-01-01

    Astrophysical gas clouds undergo thermodynamically irreversible processes and emit heat to their surroundings. Due the emission of this heat one can envision an idealized situation in which gas entropy remains (almost) constant. With this motivation in mind we derive in this paper interior solutions to the Einstein equations of General Relativity for spheres which consist of isentropic gas. In particular we investigate solutions in which the mass distribution inside the sphere has several shells. Such spheres might be considered an early stage for the formation of a "solar system".

  1. Data compression on the sphere

    CERN Document Server

    McEwen, J D; Eyers, D M; 10.1051/0004-6361/201015728

    2011-01-01

    Large data-sets defined on the sphere arise in many fields. In particular, recent and forthcoming observations of the anisotropies of the cosmic microwave background (CMB) made on the celestial sphere contain approximately three and fifty mega-pixels respectively. The compression of such data is therefore becoming increasingly important. We develop algorithms to compress data defined on the sphere. A Haar wavelet transform on the sphere is used as an energy compression stage to reduce the entropy of the data, followed by Huffman and run-length encoding stages. Lossless and lossy compression algorithms are developed. We evaluate compression performance on simulated CMB data, Earth topography data and environmental illumination maps used in computer graphics. The CMB data can be compressed to approximately 40% of its original size for essentially no loss to the cosmological information content of the data, and to approximately 20% if a small cosmological information loss is tolerated. For the topographic and il...

  2. Dyson Spheres around White Dwarfs

    CERN Document Server

    Semiz, İbrahim

    2015-01-01

    A Dyson Sphere is a hypothetical structure that an advanced civilization might build around a star to intercept all of the star's light for its energy needs. One usually thinks of it as a spherical shell about one astronomical unit (AU) in radius, and surrounding a more or less Sun-like star; and might be detectable as an infrared point source. We point out that Dyson Spheres could also be built around white dwarfs. This type would avoid the need for artificial gravity technology, in contrast to the AU-scale Dyson Spheres. In fact, we show that parameters can be found to build Dyson Spheres suitable --temperature- and gravity-wise-- for human habitation. This type would be much harder to detect.

  3. Comparison of neutron spectrum measurement methods used for the epithermal beam of the LVR-15 research reactor.

    Science.gov (United States)

    Viererbl, L; Klupák, V; Lahodová, Z; Marek, M

    2012-07-01

    The LVR-15 research reactor's horizontal channel with its epithermal neutron beam is used mainly for boron neutron capture therapy. Neutrons from the reactor core pass through a special filter before the collimator and the beam outlet. Neutron fluence and spectrum are the basic characteristics of an epithermal neutron beam. Three methods used to measure the beam's neutron spectrum are described: the activation method, a Bonner sphere spectrometer with gold activation detectors and a Bonner sphere spectrometer with LiI(Eu) scintillation detector. Examples of results are compared and discussed.

  4. A System View on Iterative MIMO Detection: Dynamic Sphere Detection versus Fixed Effort List Detection

    Directory of Open Access Journals (Sweden)

    Christina Gimmler-Dumont

    2012-01-01

    reliability information is fed back from the channel decoder to the MIMO detector. In this paper, we derive a basic framework to compare different soft-input soft-output MIMO detectors in open- and closed-loop systems. Within this framework, we analyze a depth-first sphere detector and a breadth-first fixed effort detector for different application scenarios and their effects on area and energy efficiency on the whole system. We present all system components under open- and closed-loop system aspects and determine the overall implementation cost for changing an open-loop system in a closed-loop system.

  5. Unveiling small sphere's scattering behavior

    CERN Document Server

    Tzarouchis, Dimitrios C; Sihvola, Ari

    2016-01-01

    A classical way for exploring the scattering behavior of a small sphere is to approximate Mie coefficients with a Taylor series expansion. This ansatz delivered a plethora of insightful results, mostly for small spheres supporting electric localized plasmonic resonances. However, many scattering aspects are still uncharted, especially for the case of magnetic resonances. Here, an alternative system ansatz is proposed based on the Pad\\'e approximants for the Mie coefficients. The extracted results reveal new aspects, such as the existence of a self-regulating radiative damping mechanism for the first magnetic resonance. Hence, a systematic way of exploring the scattering behavior is introduced, sharpening our understanding about sphere's scattering behavior and its emergent functionalities.

  6. Public Sphere as Digital Assemblage

    DEFF Research Database (Denmark)

    Salovaara-Moring, Inka

    the 1990s onwards digitalization brought concepts of network and complexity into the theoretical discourse. This relational turn changed the social ontology of the public sphere into a dynamic and complex system, erasing the division between the fields of reality (the world), representation (discourse...... theories. Drawing from Deleuze & Guattari (1987), Bennett (2010), and Latour (2004) in order to imagine post-human assemblages of public sphere, this paper argues for a relational ontology that emphasizes the complex interactions of political assemblages. Empirically, it draws from the author’s studies......Normative theories of public sphere have struggled with the topic of materiality. The historical narrative of the ‘public sphere’ situated the phenomenon in specific spaces, where practices (public deliberation) and language (discourse) constructed political agencies, and further publics. From...

  7. Matrix dynamics of fuzzy spheres

    CERN Document Server

    Jatkar, D P; Wadia, S R; Yogendran, K P; Jatkar, Dileep P.; Mandal, Gautam; Wadia, Spenta R.

    2002-01-01

    We study the dynamics of fuzzy two-spheres in a matrix model which represents string theory in the presence of RR flux. We analyze the stability of known static solutions of such a theory which contain commuting matrices and SU(2) representations. We find that irreducible as well as reducible representations are stable. Since the latter are of higher energy, this stability poses a puzzle. We resolve this puzzle by noting that reducible representations have marginal directions corresponding to non-spherical deformations. We obtain new static solutions by turning on these marginal deformations. These solutions now have instability or tachyonic directions. We discuss condensation of these tachyons which correspond to classical trajectories interpolating from multiple, small fuzzy spheres to a single, large sphere. We briefly discuss spatially independent configurations of a D3/D5 system described by the same matrix model which now possesses a supergravity dual.

  8. Troubleshooting vSphere storage

    CERN Document Server

    Preston, Mike

    2013-01-01

    This is a step-by-step example-oriented tutorial aimed at showing the reader how to troubleshoot a variety of vSphere storage problems, and providing the reader with solutions that can be completed with minimal effort and time in order to limit damage to work.If you are a vSphere administrator, this is the book for you. This book will provide you with 'need to know' information about the various storage transports that ESXi utilizes, the tools and techniques we can use to identify problems, and the fundamental knowledge and steps to take to troubleshoot storage-related issues. Prior knowledge

  9. Advantages of passive detectors for the determination of the cosmic ray induced neutron environment

    CERN Document Server

    Hajek, M; Schoner, W; Vana, N

    2002-01-01

    Due to the pronounced energy dependence of the neutron quality factor, accurate assessment of the biologically relevant dose requires knowledge of the spectral neutron fluence rate. Bonner sphere spectrometers (BSSs) are the only instruments which provide a sufficient response over practically the whole energy range of the cosmic ray induced neutron component. Measurements in a 62 MeV proton beam at Paul Scherrer Institute, Switzerland, and in the CERN-EU high-energy reference field led to the assumption that conventional active devices for the detection of thermal neutrons inside the BSS, e.g. /sup 6/LiI(Eu) scintillators, also respond to charged particles when used in high-energy mixed radiation fields. The effects of these particles cannot be suppressed by amplitude discrimination and are subsequently misinterpreted as neutron radiation. In contrast, paired TLD-600 and TLD-700 thermoluminescence dosemeters allow the determination of a net thermal neutron signal. (12 refs).

  10. Phase diagram of elastic spheres.

    Science.gov (United States)

    Athanasopoulou, L; Ziherl, P

    2017-02-15

    Experiments show that polymeric nanoparticles often self-assemble into several non-close-packed lattices in addition to the face-centered cubic lattice. Here, we explore theoretically the possibility that the observed phase sequences may be associated with the softness of the particles, which are modeled as elastic spheres interacting upon contact. The spheres are described by two finite-deformation theories of elasticity, the modified Saint-Venant-Kirchhoff model and the neo-Hookean model. We determine the range of indentations where the repulsion between the spheres is pairwise additive and agrees with the Hertz theory. By computing the elastic energies of nine trial crystal lattices at densities far beyond the Hertzian range, we construct the phase diagram and find the face- and body-centered cubic lattices as well as the A15 lattice and the simple hexagonal lattice, with the last two being stable at large densities where the spheres are completely faceted. These results are qualitatively consistent with observations, suggesting that deformability may indeed be viewed as a generic property that determines the phase behavior in nanocolloidal suspensions.

  11. Approximation on the complex sphere

    OpenAIRE

    Alsaud, Huda; Kushpel, Alexander; Levesley, Jeremy

    2012-01-01

    We develop new elements of harmonic analysis on the complex sphere on the basis of which Bernstein's, Jackson's and Kolmogorov's inequalities are established. We apply these results to get order sharp estimates of $m$-term approximations. The results obtained is a synthesis of new results on classical orthogonal polynomials, harmonic analysis on manifolds and geometric properties of Euclidean spaces.

  12. Hard sphere model of atom

    CERN Document Server

    Tsekov, R

    2014-01-01

    The finite size effect of electron and nucleus is accounted for in the model of atom. Due to their hard sphere repulsion the energy of the 1s orbital decreases and the corrections amount up to 8 % in Uranium. Several models for boundary conditions on the atomic nucleus surface are discussed as well.

  13. Spheres of Justice within Schools

    DEFF Research Database (Denmark)

    Sabbagh, Clara; Resh, Nura; Mor, Michal;

    2006-01-01

    This article argues that there are distinct spheres of justice within education and examines a range of justice norms and distribution rules that characterize the daily life of schools and classrooms. Moving from the macro to micro level, we identify the following five areas: the right to education...

  14. Kinetic theory of hard spheres

    NARCIS (Netherlands)

    Beijeren, H. van; Ernst, M.H.

    1979-01-01

    Kinetic equations for the hard-sphere system are derived by diagrammatic techniques. A linear equation is obtained for the one-particle-one particle equilibrium time correlation function and a nonlinear equation for the one-particle distribution function in nonequilibrium. Both equations are nonloca

  15. Infrared detectors

    CERN Document Server

    Rogalski, Antonio

    2010-01-01

    This second edition is fully revised and reorganized, with new chapters concerning third generation and quantum dot detectors, THz detectors, cantilever and antenna coupled detectors, and information on radiometry and IR optics materials. Part IV concerning focal plane arrays is significantly expanded. This book, resembling an encyclopedia of IR detectors, is well illustrated and contains many original references … a really comprehensive book.-F. Sizov, Institute of Semiconductor Physics, National Academy of Sciences, Kiev, Ukraine

  16. Simulation of flow and sediment transport in the white sturgeon spawning habitat of the Kootenai River near Bonners Ferry, Idaho

    Science.gov (United States)

    Berenbrock, Charles; Bennett, James P.

    2005-01-01

    Characterization of sediment transport of the Kootenai River in the white sturgeon spawning reach is needed by the Kootenai River White Sturgeon Recovery Team to predict sediment-transport conditions that improve spawning conditions for the white sturgeon (Acipenser transmontanus) in the Kootenai River near Bonners Ferry, Idaho. The decreasing population and spawning failure of the white sturgeon has led to much concern. Few wild juvenile sturgeon are found in the river today. The Kootenai River begins in British Columbia, Canada, and flows through Montana, Idaho, and back into British Columbia. A 15-mile reach of the Kootenai River in Idaho was studied, including the white sturgeon spawning reach that has been designated as a critical habitat near Bonners Ferry, Idaho, and a 1-mile long side channel around the western side of Shorty Island. A one-dimensional sediment-transport model of the study reach was developed, calibrated, and used to simulate the response of the hydraulic and sediment system to varying discharges and water-surface elevations. The model comprises 79 cross sections, most of which came from a previous river survey conducted in 2002-03. Bed-sediment samples collected in 2002 and additional samples collected for this study in 2004 were used in the model. The model was calibrated to discharge and water-surface elevations at two U.S. Geological Survey gaging stations. The model also was calibrated to suspended-sediment discharge at several sites in the study reach. The calibrated model was used to simulate six different management alternatives to assess erosion and deposition under varying hydraulic conditions at the end of 21 days of simulation. Alternative 1 was simulated with a discharge of 6,000 cubic feet per second (ft3/s), alternative 2 with 20,000 ft3/s, alternative 3 with 40,000 ft3/s, and alternatives 4 through 6 with 60,000 ft3/s and represents low to high discharges in the river since the construction of Libby Dam. Sediment deposition

  17. Surface field in an ensemble of superconducting spheres under external magnetic field

    CERN Document Server

    Peñaranda, A; Ramírez-Piscina, L

    1999-01-01

    We perform calculations of the magnetic field on the surface of an ensemble of superconducting spheres when placed into an external magnetic field, which is the configuration employed in superheated superconducting granule detectors. The Laplace equation is numerically solved with appropriate boundary conditions by means of an iterative procedure and a multipole expansion.

  18. Vortical flow past a sphere

    Science.gov (United States)

    Mattner, Trent; Chong, Min; Joubert, Peter

    2000-11-01

    Vortical flow past a sphere in a constant diameter pipe was studied experimentally in a guide vane apparatus similar to those used in fundamental experimental studies of vortex breakdown. The initial effect of swirl was to shorten the downstream separation bubble. For a small range of the swirl intensity, an almost stagnant upstream separation bubble formed. As the swirl intensity was increased, the bubble became unstable and an unsteady spiral formed. At high swirl intensity there was a mean recirculation region which penetrated far upstream while the flow on the downstream hemisphere was attached. Measurements of the velocity field were obtained using laser Doppler velocimetry. Analysis of these results suggests that the onset of upstream separation is associated with the formation of a negative azimuthal vorticity component which slows the axial flow near the axis of symmetry. This is consistent with inviscid distortion of the vortex filaments in the diverging flow approaching the sphere.

  19. Capillary holdup between vertical spheres

    Directory of Open Access Journals (Sweden)

    S. Zeinali Heris

    2009-12-01

    Full Text Available The maximum volume of liquid bridge left between two vertically mounted spherical particles has been theoretically determined and experimentally measured. As the gravitational effect has not been neglected in the theoretical model, the liquid interface profile is nonsymmetrical around the X-axis. Symmetry in the interface profile only occurs when either the particle size ratio or the gravitational force becomes zero. In this paper, some equations are derived as a function of the spheres' sizes, gap width, liquid density, surface tension and body force (gravity/centrifugal to estimate the maximum amount of liquid that can be held between the two solid spheres. Then a comparison is made between the result based on these equations and several experimental results.

  20. Entanglement Entropy of Two Spheres

    CERN Document Server

    Shiba, Noburo

    2012-01-01

    We study the entanglement entropy S_{AB} of a massless free scalar field on two spheres A and B whose radii are R_1 and R_2, respectively, and the distance between them is r. The state of the massless free scalar field is the vacuum state. We obtain the result that the mutual information S_{A;B}:=S_A+S_B-S_{AB} is independent of the ultraviolet cutoff and proportional to the product of the areas of the two spheres when r>>R_1,R_2, where S_A and S_B are the entanglement entropy on the inside region of A and B, respectively. We discuss possible connections of this result with the physics of black holes.

  1. Entanglement entropy of two spheres

    Science.gov (United States)

    Shiba, Noburo

    2012-07-01

    We study the entanglement entropy S AB of a massless free scalar field on two spheres A and B whose radii are R 1 and R 2, respectively, and the distance between the centers of them is r. The state of the massless free scalar field is the vacuum state. We obtain the result that the mutual information {S_{{A;B}}} equiv {S_A} + {S_B} - {S_{{AB}}} is independent of the ultraviolet cutoff and proportional to the product of the areas of the two spheres when r ≫ R 1 ,R 2,where S A and S B aretheentanglemententropyontheinsideregionof A and B, respectively. We discuss possible connections of this result with the physics of black holes.

  2. Principal Fibrations from Noncommutative Spheres

    Science.gov (United States)

    Landi, Giovanni; Suijlekom, Walter Van

    2005-11-01

    We construct noncommutative principal fibrations Sθ7→Sθ4 which are deformations of the classical SU(2) Hopf fibration over the four sphere. We realize the noncommutative vector bundles associated to the irreducible representations of SU(2) as modules of coequivariant maps and construct corresponding projections. The index of Dirac operators with coefficients in the associated bundles is computed with the Connes-Moscovici local index formula. "The algebra inclusion is an example of a not-trivial quantum principal bundle."

  3. On sphere-filling ropes

    CERN Document Server

    Gerlach, Henryk

    2010-01-01

    What is the longest rope on the unit sphere? Intuition tells us that the answer to this packing problem depends on the rope's thickness. For a countably infinite number of prescribed thickness values we construct and classify all solution curves. The simplest ones are similar to the seamlines of a tennis ball, others exhibit a striking resemblance to Turing patterns in chemistry, or to ordered phases of long elastic rods stuffed into spherical shells.

  4. Hard sphere packings within cylinders.

    Science.gov (United States)

    Fu, Lin; Steinhardt, William; Zhao, Hao; Socolar, Joshua E S; Charbonneau, Patrick

    2016-03-07

    Arrangements of identical hard spheres confined to a cylinder with hard walls have been used to model experimental systems, such as fullerenes in nanotubes and colloidal wire assembly. Finding the densest configurations, called close packings, of hard spheres of diameter σ in a cylinder of diameter D is a purely geometric problem that grows increasingly complex as D/σ increases, and little is thus known about the regime for D > 2.873σ. In this work, we extend the identification of close packings up to D = 4.00σ by adapting Torquato-Jiao's adaptive-shrinking-cell formulation and sequential-linear-programming (SLP) technique. We identify 17 new structures, almost all of them chiral. Beyond D ≈ 2.85σ, most of the structures consist of an outer shell and an inner core that compete for being close packed. In some cases, the shell adopts its own maximum density configuration, and the stacking of core spheres within it is quasiperiodic. In other cases, an interplay between the two components is observed, which may result in simple periodic structures. In yet other cases, the very distinction between the core and shell vanishes, resulting in more exotic packing geometries, including some that are three-dimensional extensions of structures obtained from packing hard disks in a circle.

  5. Mastering VMware vSphere 5

    CERN Document Server

    Lowe, Scott

    2011-01-01

    A new and updated edition of bestselling Mastering VMware vSphere 4 Written by leading VMware expert, this book covers all the features and capabilities of VMware vSphere. You'll learn how to install, configure, operate, manage, and secure the latest release.Covers all the new features and capabilities of the much-anticipated new release of VMware vSphereDiscusses the planning, installation, operation, and management for the latest releaseReviews migration to the latest vSphere softwareOffers hands-on instruction and clear explanations with real-world examples Mastering VMware vSphere is the

  6. SURFACES OF HARD-SPHERE SYSTEMS

    Directory of Open Access Journals (Sweden)

    Dietrich Stoyan

    2014-07-01

    Full Text Available In various situations surfaces appear that are formed by systems of hard spheres. Examples are porous layers as surfaces of sand heaps and biofilms or fracture surfaces of concrete. The present paper considers models where a statistically homogeneous system of hard spheres with random radii is intersected by a plane and the surface is formed by the spheres with centers close to this plane. Formulae are derived for various characteristics of such surfaces: for the porosity profile, i.e. the local porosity in dependence on the distance from the section plane and for the geometry of the sphere caps that look above the section plane.It turns out that these characteristics only depend on the first-order characteristics of the sphere system, its sphere density and the sphere radius distribution.Comparison with empirically studied biofilms shows that the model is realistic.

  7. Pixel Detectors

    OpenAIRE

    Wermes, Norbert

    2005-01-01

    Pixel detectors for precise particle tracking in high energy physics have been developed to a level of maturity during the past decade. Three of the LHC detectors will use vertex detectors close to the interaction point based on the hybrid pixel technology which can be considered the state of the art in this field of instrumentation. A development period of almost 10 years has resulted in pixel detector modules which can stand the extreme rate and timing requirements as well as the very harsh...

  8. Measuring ultraviolet-visible light transmission of intraocular lenses: double-beam mode versus integrating-sphere mode.

    Science.gov (United States)

    Akinay, Ali; Ong, Marcia D; Choi, Myoung; Karakelle, Mutlu

    2012-10-01

    This study compared integrating-sphere and double-beam methodologies for measuring the ultraviolet/visible transmission of intraocular lenses (IOLs). Transmission spectra of control IOLs and clinically explanted IOLs were measured with an optical spectrophotometer in two optical configurations: single-beam mode with integrating sphere detector and double-beam mode with photodiode detector. Effects of temperature and surface light scattering on transmittance were measured. Effects of lens power were measured and were modeled with ray-tracing software. Results indicated that transmission was consistent over a range of IOL powers when measured with the integrating-sphere configuration, but transmission gradually decreased with increasing IOL power (in a wavelength-dependent fashion) when measured with the double-beam configuration. Ray tracing indicated that the power-dependent loss in transmission was partially due to higher-powered IOLs spreading the light beam outside of the detector area. IOLs with surface light scattering had transmission spectra that differed between double-beam and integrating-sphere configurations in a power-dependent fashion. Temperature (ambient or physiological 35°C) did not affect transmission in the integrating-sphere configuration. Overall, results indicated that double-beam spectrophotometers may be useful for measuring transmittance of low-power IOLs, but an integrating-sphere configuration should be used to obtain accurate measurements of transmittance of higher-power IOLs.

  9. VMware vSphere design

    CERN Document Server

    Guthrie, Forbes

    2013-01-01

    Achieve the performance, scalability, and ROI your business needs What can you do at the start of a virtualization deployment to make things run more smoothly? If you plan, deploy, maintain, and optimize vSphere solutions in your company, this unique book provides keen insight and solutions. From hardware selection, network layout, and security considerations to storage and hypervisors, this book explains the design decisions you'll face and how to make the right choices. Written by two virtualization experts and packed with real-world strategies and examples, VMware v

  10. Entanglement entropy of round spheres

    Energy Technology Data Exchange (ETDEWEB)

    Solodukhin, Sergey N., E-mail: Sergey.Solodukhin@lmpt.univ-tours.f [Laboratoire de Mathematiques et Physique Theorique, Universite Francois-Rabelais Tours Federation Denis Poisson - CNRS, Parc de Grandmont, 37200 Tours (France)

    2010-10-18

    We propose that the logarithmic term in the entanglement entropy computed in a conformal field theory for a (d-2)-dimensional round sphere in Minkowski spacetime is identical to the logarithmic term in the entanglement entropy of extreme black hole. The near horizon geometry of the latter is H{sub 2}xS{sub d-2}. For a scalar field this proposal is checked by direct calculation. We comment on relation of this and earlier calculations to the 'brick wall' model of 't Hooft. The case of generic 4d conformal field theory is discussed.

  11. Optical Detectors

    Science.gov (United States)

    Tabbert, Bernd; Goushcha, Alexander

    Optical detectors are applied in all fields of human activities from basic research to commercial applications in communication, automotive, medical imaging, homeland security, and other fields. The processes of light interaction with matter described in other chapters of this handbook form the basis for understanding the optical detectors physics and device properties.

  12. Metal Detectors.

    Science.gov (United States)

    Harrington-Lueker, Donna

    1992-01-01

    Schools that count on metal detectors to stem the flow of weapons into the schools create a false sense of security. Recommendations include investing in personnel rather than hardware, cultivating the confidence of law-abiding students, and enforcing discipline. Metal detectors can be quite effective at afterschool events. (MLF)

  13. Floating behavior of hydrophobic glass spheres.

    Science.gov (United States)

    Liu, Xinjie; Wang, Xiaolong; Liang, Yongmin; Zhou, Feng

    2009-08-15

    When a hydrophobic solid sphere is floating on water or salt solutions with different concentrations, it is at equilibrium under the impact of gravity, buoyancy force, and curvature force, the component of surface tension in the vertical direction. We have changed the diameters of the spheres and the concentrations of the two selected salts, NaCl and NaNO(3), to study the floating behaviors of these spheres and the contributions of surface tension and buoyancy force to their floatation. Generally speaking, the surface tension plays a more important role than the buoyancy force when the gravity is small, but the buoyancy force plays an identical or a more important role when the spheres are big enough. The wettability of the spheres significantly influences the height below the contact perimeter especially in salt solutions. The theoretical calculation meniscus slope angles at the sphere three-phase contact line are in agreement with experimental results.

  14. Sphere Drag and Heat Transfer.

    Science.gov (United States)

    Duan, Zhipeng; He, Boshu; Duan, Yuanyuan

    2015-07-20

    Modelling fluid flows past a body is a general problem in science and engineering. Historical sphere drag and heat transfer data are critically examined. The appropriate drag coefficient is proposed to replace the inertia type definition proposed by Newton. It is found that the appropriate drag coefficient is a desirable dimensionless parameter to describe fluid flow physical behavior so that fluid flow problems can be solved in the simple and intuitive manner. The appropriate drag coefficient is presented graphically, and appears more general and reasonable to reflect the fluid flow physical behavior than the traditional century old drag coefficient diagram. Here we present drag and heat transfer experimental results which indicate that there exists a relationship in nature between the sphere drag and heat transfer. The role played by the heat flux has similar nature as the drag. The appropriate drag coefficient can be related to the Nusselt number. This finding opens new possibilities in predicting heat transfer characteristics by drag data. As heat transfer for flow over a body is inherently complex, the proposed simple means may provide an insight into the mechanism of heat transfer for flow past a body.

  15. The Chiral Dipolar Hard Sphere Model.

    OpenAIRE

    Mazars, Martial

    2009-01-01

    Abstract A simple molecular model of chiral molecules is presented in this paper : the chiral dipolar hard sphere model. The discriminatory interaction between enantiomers is represented by electrostatic (or magnetic) dipoles-dipoles interactions : short ranged steric repulsion are represented by hard sphere potential and, in each molecule, two point dipoles are located inside the sphere. The model is described in detail and some of its elementary properties are given ; in particul...

  16. Absolute Stability Limit for Relativistic Charged Spheres

    CERN Document Server

    Giuliani, Alessandro

    2007-01-01

    We find an exact solution for the stability limit of relativistic charged spheres for the case of constant gravitational mass density and constant charge density. We argue that this provides an absolute stability limit for any relativistic charged sphere in which the gravitational mass density decreases with radius and the charge density increases with radius. We then provide a cruder absolute stability limit that applies to any charged sphere with a spherically symmetric mass and charge distribution. We give numerical results for all cases. In addition, we discuss the example of a neutral sphere surrounded by a thin, charged shell.

  17. Small-world networks on a sphere

    Science.gov (United States)

    Corso, Gilberto; Torres Cruz, Claudia P.

    2017-01-01

    The Small-World Network on a Sphere SWNS is a non-crossing network that has no hubs and presents the small-world property diam log N with diam being the maximal distance between any two vertices and N being the number of vertices. The SWNS is constructed using a partition of the sphere and the parallels are regular sections of the sphere with constant latitude. The number of cells on the parallels, however, increases exponentially from the pole to the equator of the sphere. We analytically compute the distribution of connectivity, the clustering coefficient and the SWNS distances. The resilience of the model against selective attacks is also discussed.

  18. Phononic crystals of poroelastic spheres

    Science.gov (United States)

    Alevizaki, A.; Sainidou, R.; Rembert, P.; Morvan, B.; Stefanou, N.

    2016-11-01

    An extension of the layer-multiple-scattering method to phononic crystals of poroelastic spheres immersed in a fluid medium is developed. The applicability of the method is demonstrated on specific examples of close-packed fcc crystals of submerged water-saturated meso- and macroporous silica microspheres. It is shown that, by varying the pore size and/or the porosity, the transmission, reflection, and absorption spectra of finite slabs of these crystals are significantly altered. Strong absorption, driven by the slow waves in the poroelastic material and enhanced by multiple scattering, leads to negligible transmittance over an extended frequency range, which might be useful for practical applications in broadband acoustic shielding. The results are analyzed by reference to relevant phononic dispersion diagrams in the viscous and inertial coupling limits, and a consistent interpretation of the underlying physics is provided.

  19. The Hubble Sphere Hydrogen Survey

    CERN Document Server

    Peterson, J B; Pen, U L; Peterson, Jeffrey B.; Bandura, Kevin; Pen, Ue Li

    2006-01-01

    An all sky redshift survey, using hydrogen 21 cm emission to locate galaxies, can be used to track the wavelength of baryon acoustic oscillations imprints from z ~ 1.5 to z = 0. This will allow precise determination of the evolution of dark energy. A telescope made of fixed parabolic cylindrical reflectors offers substantial benefit for such a redshift survey. Fixed cylinders can be built for low cost, and long cylinders also allow low cost fast fourier transform techniques to be used to define thousands of simultaneous beams. A survey made with fixed reflectors naturally covers all of the sky available from it's site with good uniformity, minimizing sample variance in the measurement of the acoustic peak wavelength. Such a survey will produce about a billion redshifts, nearly a thousand times the number available today. The survey will provide a three dimensional mapping of a substantial fraction of the Hubble Sphere.

  20. Scattering by two spheres: Theory and experiment

    DEFF Research Database (Denmark)

    Bjørnø, Irina; Jensen, Leif Bjørnø

    1998-01-01

    on three issues: (1) to develop a simplified theory for scattering by two elastical spheres; (2) to measure the scattering by two spheres in a water tank, and (3) to compare the theoretical/numerical results with the measured data. A number of factors influencing multiple scattering, including...

  1. Electric dipoles on the Bloch sphere

    CERN Document Server

    Vutha, Amar C

    2014-01-01

    The time evolution of a two-level quantum mechanical system can be geometrically described using the Bloch sphere. By mapping the Bloch sphere evolution onto the dynamics of oscillating electric dipoles, we provide a physically intuitive link between classical electromagnetism and the electric dipole transitions of atomic & molecular physics.

  2. The Positive Freedom of the Public Sphere

    DEFF Research Database (Denmark)

    Hansen, Ejvind

    2015-01-01

    The relationship between democracy and the media since the appearance of Habermas' major texts in the 1960s has been articulated through theories of the public sphere. The structure of the public sphere is significantly influenced by the communicative media, and the emergence of the internet thus...

  3. Reversible thermal gelation in soft spheres

    DEFF Research Database (Denmark)

    Kapnistos, M.; Vlassopoulos, D.; Fytas, G.

    2000-01-01

    Upon heating, concentrated solutions of star polymers and block copolymer micelles in a good solvent, representing soft spheres, undergo a reversible gelation. This phenomenon is attributed to the formation of clusters causing a partial dynamic arrest of the swollen interpenetrating spheres at hi...

  4. Innovation embedded in entrepreneurs’ networks in private and public spheres

    DEFF Research Database (Denmark)

    Schøtt, Thomas; Cheraghi, Maryam; Rezaei, Shahamak;

    2014-01-01

    Global studies have found tendencies: traditional culture promotes entrepreneurs' networking in the private sphere, impeding innovation, whereas secular-rational culture facilitates networking in the public sphere, benefiting innovation. This embeddedness is here scrutinised in contrasting...... is negatively affected by private sphere networking and positively affected by public sphere networking, but innovation is less promoted by public sphere networking in China than in Denmark....

  5. Instability of Extremal Relativistic Charged Spheres

    CERN Document Server

    Anninos, P; Anninos, Peter; Rothman, Tony

    2002-01-01

    With the question, ``Can relativistic charged spheres form extremal black holes?" in mind, we investigate the properties of such spheres from a classical point of view. The investigation is carried out numerically by integrating the Oppenheimer-Volkov equation for relativistic charged fluid spheres and finding interior Reissner-Nordstr\\"om solutions for these objects. We consider both constant density and adiabatic equations of state, as well as several possible charge distributions, and examine stability by both a normal mode and an energy analysis. In all cases, the stability limit for these spheres lies between the extremal ($Q = M$) limit and the black hole limit ($R = R_+$). That is, we find that charged spheres undergo gravitational collapse before they reach $Q = M$, suggesting that extremal Reissner-Nordtr\\"om black holes produced by collapse are ruled out. A general proof of this statement would support a strong form of the cosmic censorship hypothesis, excluding not only stable naked singularities, ...

  6. Mixed polarization in determining the film thickness of a silicon sphere by spectroscopic ellipsometry

    Institute of Scientific and Technical Information of China (English)

    Zhang Ji-Tao; Wu Xue-Jian; Li Yan

    2012-01-01

    The effect of a spherical shape on the measurement result of spectroscopic ellipsometry (SE) is analyzed,and a method to eliminate this effect is proposed.Based on the simulation result of the SE measurement on a silicon sphere by ray tracking,we find that the sphere makes the parallel incident beam of the SE be divergent after reflection,and the measurement error of the SE caused by this phenomenon is explained by the mixed polarization theory.By settling an aperture in front of the detector of the SE,we can almost eliminate the error.For the silicon sphere with a diameter of 94 mm used in the Avogadro project,the thickness error of the oxide layer caused by the spherical shape can be reduced from 0.73 nm to 0.04 nm by using the proposed method.The principle of the method and the results of the experimental verification are presented.

  7. Measurement of the neutron spectrum in a room with an accelerator Varian 2300C/D Linac using the Bonner multisphere spectrometer; Medicao do espectro de neutrons em uma sala com um acelerador Varian 2300C/D Linav usando o espectrometro de multiesferas de Bonner

    Energy Technology Data Exchange (ETDEWEB)

    Cavalcante, D.B.S., E-mail: cavalcante@ird.gov.b [Universidade Federal do Rio de Janeiro (IF/UFRJ), RJ (Brazil). Inst. de Fisica; Fonseca, E.S. da, E-mail: evaldo@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Lemos Junior, R.M. [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), RJ (Brazil); Batista, D.V.S. [Instituto Nacional do Cancer (INCa), Rio de Janeiro, RJ (Brazil)

    2009-07-01

    The generated neutron field varies considerably and depends on the beam energy, on the shielding of the accelerator, on the filters for beam homogeneity, and also on the mobile collimators and geometry of irradiation. The estimation of the component relative to the photoneutrons has practical interest for evaluation of the radiological risks for the workers and for the patient as well. Due to the high frequency magnetic field, and to the photon abundance resulting of the escape and scattering at treatment room, those measurements present some difficulties. Measurements of the neutron fields can be made with a Bonner spectrometer. Those system was calibrated with referred neutron standard sources and used for make measurements on a spot of the room where a Variant 2300C/D Linac is installed. The unfolding process used the BUNKI computer code for determination of the neutron spectra at the measurement spot

  8. Pixel detectors

    CERN Document Server

    Passmore, M S

    2001-01-01

    positions on the detector. The loss of secondary electrons follows the profile of the detector and increases with higher energy ions. studies of the spatial resolution predict a value of 5.3 lp/mm. The image noise in photon counting systems is investigated theoretically and experimentally and is shown to be given by Poisson statistics. The rate capability of the LAD1 was measured to be 250 kHz per pixel. Theoretical and experimental studies of the difference in contrast for ideal charge integrating and photon counting imaging systems were carried out. It is shown that the contrast differs and that for the conventional definition (contrast = (background - signal)/background) the photon counting device will, in some cases, always give a better contrast than the integrating system. Simulations in MEDICI are combined with analytical calculations to investigate charge collection efficiencies (CCE) in semiconductor detectors. Different pixel sizes and biasing conditions are considered. The results show charge shari...

  9. Calorimeter detectors

    CERN Document Server

    de Barbaro, P; The ATLAS collaboration

    2013-01-01

    Although the instantaneous and integrated luminosity in HL-LHC will be far higher than the LHC detectors were originally designed for, the Barrel calorimeters of the four experiments are expected to continue to perform well  throughout the Phase II program. The conditions for the End-Cap calorimeters are far more challenging and whilst some detectors will require relatively modest changes, others require far more substantial upgrades. We present the results of longevity and performance studies for the calorimeter systems of the four main LHC experiments and outline the upgrade options under consideration. We include a discussion of the R&D required to make the final technology choices for the upgraded detectors.

  10. Hitting spheres on hyperbolic spaces

    CERN Document Server

    Cammarota, Valentina

    2011-01-01

    For a hyperbolic Brownian motion on the Poincar\\'e half-plane $\\mathbb{H}^2$, starting from a point of hyperbolic coordinates $z=(\\eta, \\alpha)$ inside a hyperbolic disc $U$ of radius $\\bar{\\eta}$, we obtain the probability of hitting the boundary $\\partial U$ at the point $(\\bar \\eta,\\bar \\alpha)$. For $\\bar{\\eta} \\to \\infty$ we derive the asymptotic Cauchy hitting distribution on $\\partial \\mathbb{H}^2$ and for small values of $\\eta$ and $\\bar \\eta$ we obtain the classical Euclidean Poisson kernel. The exit probabilities $\\mathbb{P}_z\\{T_{\\eta_1}sphere. For the hyperbolic half-space $\\mathbb{H}^n$ we obtain the Poisson kernel of a ball in terms of a series involving Gegenbauer polynomials and hypergeometric functions. For small do...

  11. Lines, Circles, Planes and Spheres

    CERN Document Server

    Purdy, George B

    2009-01-01

    Let $S$ be a set of $n$ points in $\\mathbb{R}^3$, no three collinear and not all coplanar. If at most $n-k$ are coplanar and $n$ is sufficiently large, the total number of planes determined is at least $1 + k \\binom{n-k}{2}-\\binom{k}{2}(\\frac{n-k}{2})$. For similar conditions and sufficiently large $n$, (inspired by the work of P. D. T. A. Elliott in \\cite{Ell67}) we also show that the number of spheres determined by $n$ points is at least $1+\\binom{n-1}{3}-t_3^{orchard}(n-1)$, and this bound is best possible under its hypothesis. (By $t_3^{orchard}(n)$, we are denoting the maximum number of three-point lines attainable by a configuration of $n$ points, no four collinear, in the plane, i.e., the classic Orchard Problem.) New lower bounds are also given for both lines and circles.

  12. Aerial View of StenniSphere

    Science.gov (United States)

    2001-01-01

    StenniSphere, the John C. Stennis Space Center's visitor center in Hancock County, Miss., features a 14,000-square-foot museum and outdoor exhibits about Stennis Space Center. Designed to entertain while educating, StenniSphere includes informative displays and exhibits from NASA, the Naval Meteorology and Oceanography Command, and other resident agencies. Recently named Mississippi's Travel Attraction of the Year, StenniSphere hosted a quarter of a million visitors in its first year and is a major school field trip destination.

  13. Full-field optical coherence tomography apply in sphere measurements

    Science.gov (United States)

    Shi, Wei; Li, Weiwei; li, Juncheng; Wang, Jingyu; Wang, Jianguo

    2016-10-01

    The geometry of a spherical surface, for example that of a precision optic, is completely determined by the radius -of-curvature at one point and the deviation from the perfect spherical form at all other points of the sphere. Full-field Optical Coherence Tomography (FF-OCT) is a parallel detection OCT technique that utilizes a 2D detector array. This technique avoids mechanical scanning in imaging optics, thereby speeding up the imaging process and enhancing the quality of images. The current paper presents an FF-OCT instrument that is designed to be used in sphere measurement with the principle of multiple delays (MD) OCT to evaluate the curvature and radius of curved objects in single-shot imaging. The optimum combination of the MD principle with the FF-OCT method was evaluated, and the radius of a metal ball was measured with this method. The generated 2n-1 contour lines were obtained by using an MDE with n delays in a single en-face OCT image. This method of measurement, it engaged in the measurement accuracy of spherical and enriches the means of measurement, to make a spherical scan techniques flexible application.

  14. SPHERE IRDIS and IFS astrometric strategy and calibration

    CERN Document Server

    Maire, Anne-Lise; Dohlen, Kjetil; Lagrange, Anne-Marie; Gratton, Raffaele; Chauvin, Gael; Desidera, Silvano; Girard, Julien H; Milli, Julien; Vigan, Arthur; Zins, Gerard; Delorme, Philippe; Beuzit, Jean-Luc; Claudi, Riccardo U; Feldt, Markus; Mouillet, David; Puget, Pascal; Turatto, Massimo; Wildi, Francois

    2016-01-01

    We present the current results of the astrometric characterization of the VLT planet finder SPHERE over 2 years of on-sky operations. We first describe the criteria for the selection of the astrometric fields used for calibrating the science data: binaries, multiple systems, and stellar clusters. The analysis includes measurements of the pixel scale and the position angle with respect to the North for both near-infrared subsystems, the camera IRDIS and the integral field spectrometer IFS, as well as the distortion for the IRDIS camera. The IRDIS distortion is shown to be dominated by an anamorphism of 0.60+/-0.02% between the horizontal and vertical directions of the detector, i.e. 6 mas at 1". The anamorphism is produced by the cylindrical mirrors in the common path structure hence common to all three SPHERE science subsystems (IRDIS, IFS, and ZIMPOL), except for the relative orientation of their field of view. The current estimates of the pixel scale and North angle for IRDIS are 12.255+/-0.009 milliarcseco...

  15. XMASS detector

    Energy Technology Data Exchange (ETDEWEB)

    Abe, K. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Hieda, K. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Hiraide, K. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Hirano, S. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Kishimoto, Y.; Kobayashi, K.; Moriyama, S. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Nakagawa, K. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Nakahata, M. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Nishiie, H. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Ogawa, H. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); and others

    2013-07-11

    The XMASS project aims to detect dark matter, pp and {sup 7}Be solar neutrinos, and neutrinoless double beta decay using ultra pure liquid xenon. The first phase of the XMASS experiment searches for dark matter. In this paper, we describe the XMASS detector in detail, including its configuration, data acquisition equipment and calibration system.

  16. XMASS detector

    CERN Document Server

    Abe, K; Hiraide, K; Hirano, S; Kishimoto, Y; Kobayashi, K; Moriyama, S; Nakagawa, K; Nakahata, M; Nishiie, H; Ogawa, H; Oka, N; Sekiya, H; Shinozaki, A; Suzuki, Y; Takeda, A; Takachio, O; Ueshima, K; Umemoto, D; Yamashita, M; Yang, B S; Tasaka, S; Liu, J; Martens, K; Hosokawa, K; Miuchi, K; Murata, A; Onishi, Y; Otsuka, Y; Takeuchi, Y; Kim, Y H; Lee, K B; Lee, M K; Lee, J S; Fukuda, Y; Itow, Y; Nishitani, Y; Masuda, K; Takiya, H; Uchida, H; Kim, N Y; Kim, Y D; Kusaba, F; Motoki, D; Nishijima, K; Fujii, K; Murayama, I; Nakamura, S

    2013-01-01

    The XMASS project aims to detect dark matter, pp and $^{7}$Be solar neutrinos, and neutrinoless double beta decay using ultra pure liquid xenon. The first phase of the XMASS experiment searches for dark matter. In this paper, we describe the XMASS detector in detail, including its configuration, data acquisition equipment and calibration system.

  17. Computer simulation of rod-sphere mixtures

    CERN Document Server

    Antypov, D

    2003-01-01

    Results are presented from a series of simulations undertaken to investigate the effect of adding small spherical particles to a fluid of rods which would otherwise represent a liquid crystalline (LC) substance. Firstly, a bulk mixture of Hard Gaussian Overlap particles with an aspect ratio of 3:1 and hard spheres with diameters equal to the breadth of the rods is simulated at various sphere concentrations. Both mixing-demixing and isotropic-nematic transition are studied using Monte Carlo techniques. Secondly, the effect of adding Lennard-Jones particles to an LC system modelled using the well established Gay-Berne potential is investigated. These rod-sphere mixtures are simulated using both the original set of interaction parameters and a modified version of the rod-sphere potential proposed in this work. The subject of interest is the internal structure of the binary mixture and its dependence on density, temperature, concentration and various parameters characterising the intermolecular interactions. Both...

  18. ANALYSIS OF MECHANISMS FINANCING OF CULTURAL SPHERE

    Directory of Open Access Journals (Sweden)

    Costandachi Gheorghe

    2008-01-01

    Full Text Available In this work is made analysis concern basically state structures of culture and arts activities, is describes the problems are met during the reforming process the financial mechanisms in cultural sphere. Author disclosed the ways evolve private and estate financing cultural sphere, also is disclosed why is need estate financial support. The work contains something detailed measures actions to improve financial and mechanisms financing of cultural sphere. Analyzing questions of modernization of budgetary financing of branch the author have formulated effectiveness of use of budgetary funds at all levels in cultural structures and proposed the ways of finishing of market reforms in cinematography. In the final of work is presented scheme system of financing, formation and distribution of financial resources in cinematography and is making conclusions and is offered wais of the solutions created present situation in this sphere in Moldova.

  19. Spheres of Exemption, Figures of Exclusion

    DEFF Research Database (Denmark)

    , the history of ideas, social science, political science and literature studies, Spheres of Exemption, Figures of Exclusion offers thirteen investigations into the co-constitutive relationship between subjectivity and political and legal order, combining theoretical reflection with empirical and historical...

  20. Scalar Casimir effect between two concentric spheres

    CERN Document Server

    Ozcan, Mustafa

    2012-01-01

    The Casimir effect giving rise to an attractive force between the closely spaced two concentric spheres that confine the massless scalar field is calculated by using a direct mode summation with contour integration in the complex plane of eigenfrequencies. We devoleped a new approach appropriate for the calculation of the Casimir energy for spherical boundary conditions. The Casimir energy for a massless scalar field between the closely spaced two concentric spheres coincides with the Casimir energy of the parallel plates for a massless scalar field in the limit when the dimensionless parameter {\\eta}, ({\\eta}=((a-b)/(\\surd(ab))) where a (b) is inner (outer) radius of sphere), goes to zero. The efficiency of new approach is demonstrated by calculation of the Casimir energy for a massless scalar field between the closely spaced two concentric half spheres. PACS number(s): 03.70.+k, 12.20.DS, 11.10.Gh

  1. Directional spin wavelets on the sphere

    CERN Document Server

    McEwen, Jason D; Büttner, Martin; Peiris, Hiranya V; Wiaux, Yves

    2015-01-01

    We construct a directional spin wavelet framework on the sphere by generalising the scalar scale-discretised wavelet transform to signals of arbitrary spin. The resulting framework is the only wavelet framework defined natively on the sphere that is able to probe the directional intensity of spin signals. Furthermore, directional spin scale-discretised wavelets support the exact synthesis of a signal on the sphere from its wavelet coefficients and satisfy excellent localisation and uncorrelation properties. Consequently, directional spin scale-discretised wavelets are likely to be of use in a wide range of applications and in particular for the analysis of the polarisation of the cosmic microwave background (CMB). We develop new algorithms to compute (scalar and spin) forward and inverse wavelet transforms exactly and efficiently for very large data-sets containing tens of millions of samples on the sphere. By leveraging a novel sampling theorem on the rotation group developed in a companion article, only hal...

  2. Acoustic levitation of a large solid sphere

    Science.gov (United States)

    Andrade, Marco A. B.; Bernassau, Anne L.; Adamowski, Julio C.

    2016-07-01

    We demonstrate that acoustic levitation can levitate spherical objects much larger than the acoustic wavelength in air. The acoustic levitation of an expanded polystyrene sphere of 50 mm in diameter, corresponding to 3.6 times the wavelength, is achieved by using three 25 kHz ultrasonic transducers arranged in a tripod fashion. In this configuration, a standing wave is created between the transducers and the sphere. The axial acoustic radiation force generated by each transducer on the sphere was modeled numerically as a function of the distance between the sphere and the transducer. The theoretical acoustic radiation force was verified experimentally in a setup consisting of an electronic scale and an ultrasonic transducer mounted on a motorized linear stage. The comparison between the numerical and experimental acoustic radiation forces presents a good agreement.

  3. vSphere high performance cookbook

    CERN Document Server

    Sarkar, Prasenjit

    2013-01-01

    vSphere High Performance Cookbook is written in a practical, helpful style with numerous recipes focusing on answering and providing solutions to common, and not-so common, performance issues and problems.The book is primarily written for technical professionals with system administration skills and some VMware experience who wish to learn about advanced optimization and the configuration features and functions for vSphere 5.1.

  4. Effective Depletion Potential of Colloidal Spheres

    Institute of Scientific and Technical Information of China (English)

    LI Wei-Hua; MA Hong-Ru

    2004-01-01

    @@ A new semianalytical method, which is a combination of the density functional theory with Rosenfeld density functional and the Ornstein-Zernike equation, is proposed for the calculation of the effective depletion potentials between a pair of big spheres immersed in a small hard sphere fluid. The calculated results are almost identical to the integral equation method with the Percus-Yevick approximation, and are also in agreement well with the Monte Carlo simulation results.

  5. Gender, Diversity and the European Public Sphere

    DEFF Research Database (Denmark)

    Pristed Nielsen, Helene

    2009-01-01

    This paper argues that feminist criticism of Habermasian theory leads to new ways of approaching empirical analyses of public sphere deliberation, and gives some concrete indications of which methodological consequences such a critique may lead to.......This paper argues that feminist criticism of Habermasian theory leads to new ways of approaching empirical analyses of public sphere deliberation, and gives some concrete indications of which methodological consequences such a critique may lead to....

  6. Point defects in hard-sphere crystals

    OpenAIRE

    Pronk, S.; Frenkel, D.

    2001-01-01

    We report numerical calculations of the concentration of interstitials in hard-sphere crystals. We find that, in a three-dimensional fcc hard-sphere crystal at the melting point, the concentration of interstitials is 2 * 10^-8. This is some three orders of magnitude lower than the concentration of vacancies. A simple, analytical estimate yields a value that is in fair agreement with the numerical results.

  7. vSphere virtual machine management

    CERN Document Server

    Fitzhugh, Rebecca

    2014-01-01

    This book follows a step-by-step tutorial approach with some real-world scenarios that vSphere businesses will be required to overcome every day. This book also discusses creating and configuring virtual machines and also covers monitoring virtual machine performance and resource allocation options. This book is for VMware administrators who want to build their knowledge of virtual machine administration and configuration. It's assumed that you have some experience with virtualization administration and vSphere.

  8. Geometrical Dynamics in a Transitioning Superconducting Sphere

    Directory of Open Access Journals (Sweden)

    Claycomb J. R.

    2006-10-01

    Full Text Available Recent theoretical works have concentrated on calculating the Casimir effect in curved spacetime. In this paper we outline the forward problem of metrical variation due to the Casimir effect for spherical geometries. We consider a scalar quantum field inside a hollow superconducting sphere. Metric equations are developed describing the evolution of the scalar curvature after the sphere transitions to the normal state.

  9. Inverse Magnus effect on a rotating sphere

    Science.gov (United States)

    Kim, Jooha; Park, Hyungmin; Choi, Haecheon; Yoo, Jung Yul

    2011-11-01

    In this study, we investigate the flow characteristics of rotating spheres in the subcritical Reynolds number (Re) regime by measuring the drag and lift forces on the sphere and the two-dimensional velocity in the wake. The experiment is conducted in a wind tunnel at Re = 0 . 6 ×105 - 2 . 6 ×105 and the spin ratio (ratio of surface velocity to the free-stream velocity) of 0 (no spin) - 0.5. The drag coefficient on a stationary sphere remains nearly constant at around 0.52. However, the magnitude of lift coefficient is nearly zero at Re Magnus effect, depending on the magnitudes of the Reynolds number and spin ratio. The velocity field measured from a particle image velocimetry (PIV) indicates that non-zero lift coefficient on a stationary sphere at Re > 2 . 0 ×105 results from the asymmetry of separation line, whereas the inverse Magnus effect for the rotating sphere results from the differences in the boundary-layer growth and separation along the upper and lower sphere surfaces. Supported by the WCU, Converging Research Center and Priority Research Centers Program, NRF, MEST, Korea.

  10. Semiconductor Detectors; Detectores de Semiconductores

    Energy Technology Data Exchange (ETDEWEB)

    Cortina, E.

    2007-07-01

    Particle detectors based on semiconductor materials are among the few devices used for particle detection that are available to the public at large. In fact we are surrounded by them in our daily lives: they are used in photoelectric cells for opening doors, in digital photographic and video camera, and in bar code readers at supermarket cash registers. (Author)

  11. Resonant impedance matchers for Mario Schenberg detector

    Energy Technology Data Exchange (ETDEWEB)

    Frajuca, Carlos; Bortoli, Fabio S. [Centro Federal de Educacao Tecnologica de Sao Paulo, SP (Brazil)

    2006-07-01

    'Mario Schenberg' is a spherical resonant-mass gravitational wave (GW) detector that will be part of a GW detection array of two detectors, the other one is been built in The Netherlands. Their resonant frequencies will be around 3.2 kHz with a bandwidth of about 200 Hz. This range of frequencies is new in a field where the typical frequencies lay below 1 kHz, making the transducer development much more complex. Some studies indicated that using low mass mechanical resonators (used for impedance matching to the parametric transducer, in a cold damping regime), allow the detector to reach the standard quantum limit. In this work we describe the study of mechanical impedance matcher resonators used to obtain a better coupling between the sphere and the transducers and keeping the same calibration for all transducers, this has been show to be not a easy task since the differential motions of the sphere surface propagates to the motions of the resonant mechanical impedance matchers, when it can be done then the next step is to calculate the effective mass of the resonating mechanical impedance matcher and then, calculate the detector sensitivity, this is also complicated because there is a spread in the resonant mechanical impedance matcher frequencies. (author)

  12. Terminal energy distribution of blast waves from bursting spheres

    Science.gov (United States)

    Adamczyk, A. A.; Strehlow, R. A.

    1977-01-01

    The calculation results for the total energy delivered to the surroundings by the burst of an idealized massless sphere containing an ideal gas are presented. The logic development of various formulas for sphere energy is also presented. For all types of sphere bursts the fraction of the total initial energy available in the sphere that is delivered to the surroundings is shown to lie between that delivered for the constant pressure addition of energy to a source region and that delivered by isentropic expansion of the sphere. The relative value of E sub/Q increases at fixed sphere pressure/surrounding pressure as sphere temperature increases because the velocity of sound increases.

  13. Collinear swimmer propelling a cargo sphere at low Reynolds number

    CERN Document Server

    Felderhof, B U

    2014-01-01

    The swimming velocity and rate of dissipation of a linear chain consisting of two or three little spheres and a big sphere is studied on the basis of low Reynolds number hydrodynamics. The big sphere is treated as a passive cargo, driven by the tail of little spheres via hydrodynamic and direct elastic interaction. The fundamental solution of Stokes' equations in the presence of a sphere with no-slip boundary condition, as derived by Oseen, is used to model the hydrodynamic interactions between the big sphere and the little spheres.

  14. The Separate Spheres Model of Gendered Inequality.

    Science.gov (United States)

    Miller, Andrea L; Borgida, Eugene

    2016-01-01

    Research on role congruity theory and descriptive and prescriptive stereotypes has established that when men and women violate gender stereotypes by crossing spheres, with women pursuing career success and men contributing to domestic labor, they face backlash and economic penalties. Less is known, however, about the types of individuals who are most likely to engage in these forms of discrimination and the types of situations in which this is most likely to occur. We propose that psychological research will benefit from supplementing existing research approaches with an individual differences model of support for separate spheres for men and women. This model allows psychologists to examine individual differences in support for separate spheres as they interact with situational and contextual forces. The separate spheres ideology (SSI) has existed as a cultural idea for many years but has not been operationalized or modeled in social psychology. The Separate Spheres Model presents the SSI as a new psychological construct characterized by individual differences and a motivated system-justifying function, operationalizes the ideology with a new scale measure, and models the ideology as a predictor of some important gendered outcomes in society. As a first step toward developing the Separate Spheres Model, we develop a new measure of individuals' endorsement of the SSI and demonstrate its reliability, convergent validity, and incremental predictive validity. We provide support for the novel hypotheses that the SSI predicts attitudes regarding workplace flexibility accommodations, income distribution within families between male and female partners, distribution of labor between work and family spheres, and discriminatory workplace behaviors. Finally, we provide experimental support for the hypothesis that the SSI is a motivated, system-justifying ideology.

  15. The Separate Spheres Model of Gendered Inequality.

    Directory of Open Access Journals (Sweden)

    Andrea L Miller

    Full Text Available Research on role congruity theory and descriptive and prescriptive stereotypes has established that when men and women violate gender stereotypes by crossing spheres, with women pursuing career success and men contributing to domestic labor, they face backlash and economic penalties. Less is known, however, about the types of individuals who are most likely to engage in these forms of discrimination and the types of situations in which this is most likely to occur. We propose that psychological research will benefit from supplementing existing research approaches with an individual differences model of support for separate spheres for men and women. This model allows psychologists to examine individual differences in support for separate spheres as they interact with situational and contextual forces. The separate spheres ideology (SSI has existed as a cultural idea for many years but has not been operationalized or modeled in social psychology. The Separate Spheres Model presents the SSI as a new psychological construct characterized by individual differences and a motivated system-justifying function, operationalizes the ideology with a new scale measure, and models the ideology as a predictor of some important gendered outcomes in society. As a first step toward developing the Separate Spheres Model, we develop a new measure of individuals' endorsement of the SSI and demonstrate its reliability, convergent validity, and incremental predictive validity. We provide support for the novel hypotheses that the SSI predicts attitudes regarding workplace flexibility accommodations, income distribution within families between male and female partners, distribution of labor between work and family spheres, and discriminatory workplace behaviors. Finally, we provide experimental support for the hypothesis that the SSI is a motivated, system-justifying ideology.

  16. Water exit dynamics of buoyant spheres

    Science.gov (United States)

    Truscott, Tadd T.; Epps, Brenden P.; Munns, Randy H.

    2016-11-01

    Buoyant spheres released below the free surface can rise well above the surface in a phenomenon known as pop-up. Contrary to intuition, increasing the release depth sometimes results in a lower pop-up height. We present the pop-up height of rising buoyant spheres over a range of release depths (1-12.5 diameters) and Reynolds numbers (4 ×104 to 6 ×105 ). While the dynamics of rising buoyant spheres and bubbles has been thoroughly investigated for Reynolds numbers below 104, pop-up in these larger-Reynolds-number regimes has not been studied. Yet the underwater motions of the sphere for the Reynolds numbers we study are the key to understanding the pop-up height. Two major regimes are apparent: vertical and oscillatory. The vertical regime exhibits a nearly vertical underwater trajectory and results in the largest pop-up heights. The oscillatory regime exhibits an underwater trajectory with periodic lateral motions and results in lower pop-up heights; this periodic lateral motion is modulated by unsteady vortex shedding in the wake of the sphere. Despite these complex fluid structure interactions, the experiments presented herein yield extremely repeatable results.

  17. Robotics Programming Competition Spheres, Russian Part

    Science.gov (United States)

    Sadovski, Andrei; Kukushkina, Natalia; Biryukova, Natalia

    2016-07-01

    Spheres" such name was done to Russian part of the Zero Robotics project which is a student competition devoted to programming of SPHERES (SPHERES - Synchronized Position Hold Engage and Reorient Experimental Satellites are the experimental robotics devices which are capable of rotation and translation in all directions, http://ssl.mit.edu/spheres/), which perform different operations on the board of International Space Station. Competition takes place online on http://zerorobotics.mit.edu. The main goal is to develop a program for SPHERES to solve an annual challenge. The end of the tournament is the real competition in microgravity on the board of ISS with a live broadcast. The Russian part of the tournament has only two years history but the problems, organization and specific are useful for the other educational projects especially for the international ones. We introduce the history of the competition, its scientific and educational goals in Russia and describe the participation of Russian teams in 2014 and 2015 tournaments. Also we discuss the organizational problems.

  18. Classical and quantum dynamics of the sphere

    Science.gov (United States)

    Lasukov, Vladimir; Moldovanova, Evgeniia; Abdrashitova, Maria; Malik, Hitendra; Gorbacheva, Ekaterina

    2016-07-01

    In Minkowski space, there has been developed the mathematic quantum model of the real particle located on the sphere evolving owing to the negative pressure inside the sphere. The developed model is analogous to the geometrodynamic model of the Lemaitre-Friedmann primordial atom in superspace-time, whose spatial coordinate is the scale factor functioning as a radial coordinate. There is a formulation of quantum geometrodynamics in which the spatial coordinate is an offset of the scale factor and wave function at the same time. With the help of the Dirac procedure for extracting the root from the Hamiltonian operator we have constructed a Dirac quantum dynamics of the sphere with fractional spin.

  19. The phase behavior of linear and partially flexible hard-sphere chain fluids and the solubility of hard spheres in hard-sphere chain fluids

    NARCIS (Netherlands)

    Oyarzun, B.A.; Van Westen, T.; Vlugt, T.J.H.

    2013-01-01

    he liquid crystal phase behavior of linear and partially flexible hard-sphere chain fluids and the solubility of hard spheres in hard-sphere chain fluids are studied by constant pressure Monte Carlo simulations. An extensive study on the phase behavior of linear fluids with a length of 7, 8, 9, 10,

  20. Path integral representations on the complex sphere

    Energy Technology Data Exchange (ETDEWEB)

    Grosche, C. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2007-08-15

    In this paper we discuss the path integral representations for the coordinate systems on the complex sphere S{sub 3C}. The Schroedinger equation, respectively the path integral, separates in exactly 21 orthogonal coordinate systems. We enumerate these coordinate systems and we are able to present the path integral representations explicitly in the majority of the cases. In each solution the expansion into the wave-functions is stated. Also, the kernel and the corresponding Green function can be stated in closed form in terms of the invariant distance on the sphere, respectively on the hyperboloid. (orig.)

  1. vSphere design best practices

    CERN Document Server

    Bolander, Brian

    2014-01-01

    An easy-to-follow guide full of hands-on examples of real-world design best practices. Each topic is explained and placed in context, and for the more inquisitive, there are more details on the concepts used.If you wish to learn about vSphere best practices and how to apply them when designing virtual, high performance, reliable datacenters that support business critical applications to work more efficiently and to prepare for official certifications, this is the book for you. Readers should possess a good working knowledge of vSphere as well as servers, storage, and networking.

  2. Willmore energy estimates in conformal Berger spheres

    Energy Technology Data Exchange (ETDEWEB)

    Barros, Manuel, E-mail: mbarros@ugr.es [Departamento de Geometria y Topologia, Facultad de Ciencias Universidad de Granada, 1807 Granada (Spain); Ferrandez, Angel, E-mail: aferr@um.es [Departamento de Matematicas, Universidad de Murcia Campus de Espinardo, 30100 Murcia (Spain)

    2011-07-15

    Highlights: > The Willmore energy is computed in a wide class of surfaces. > Isoperimetric inequalities for the Willmore energy of Hopf tori are obtained. > The best possible lower bound is achieved on isoareal Hopf tori. - Abstract: We obtain isoperimetric inequalities for the Willmore energy of Hopf tori in a wide class of conformal structures on the three sphere. This class includes, on the one hand, the family of conformal Berger spheres and, on the other hand, a one parameter family of Lorentzian conformal structures. This allows us to give the best possible lower bound of Willmore energies concerning isoareal Hopf tori.

  3. Does Negative Type Characterize the Round Sphere?

    DEFF Research Database (Denmark)

    Kokkendorff, Simon Lyngby

    2007-01-01

    We discuss the measure theoretic metric invariants extent, mean distance and symmetry ratio and their relation to the concept of negative type of a metric space. A conjecture stating that a compact Riemannian manifold with symmetry ratio 1 must be a round sphere, was put forward in a previous paper....... We resolve this conjecture in the class of Riemannian symmetric spaces by showing, that a Riemannian manifold with symmetry ratio 1 must be of negative type and that the only compact Riemannian symmetric spaces of negative type are the round spheres....

  4. Simulation of the response functions of an extended range neutron multisphere spectrometer using FLUKA

    Science.gov (United States)

    Wang, Pan-Feng; Ding, Ya-Dong; Wang, Qing-Bin; Ma, Zhong-Jian; Guo, Si-Ming; Li, Guan-Jia

    2015-07-01

    In this paper, the distribution of radiation field in the CSNS spectrometer hall at Dongguan, China, was simulated by the FLUKA program. The results show that the radiation field of the high energy proton accelerator is dominated by neutron radiation, with a broad range of neutron energies, spanning about eleven orders of magnitude. Simulation and calculation of the response functions of four Bonner spheres with a simplified model is done with FLUKA and MCNPX codes respectively, proving the feasibility of the FLUKA program for this application and the correctness of the calculation method. Using the actual model, we simulate and calculate the energy response functions of Bonner sphere detectors with polyethylene layers of different diameters, including detectors with lead layers, using the FLUKA code. Based on the simulation results, we select eleven detectors as the basic structure for an Extended Range Neutron Multisphere Spectrometer (ERNMS).

  5. Simulation of the response functions of an extended range neutron multisphere spectrometer using FLUKA

    Institute of Scientific and Technical Information of China (English)

    WANG Pan-Feng; DING Ya-Dong; WANG Qing-Bin; MA Zhong-Jian; GUO Si-Ming; LI Guan-Jia

    2015-01-01

    In this paper,the distribution of radiation field in the CSNS spectrometer hall at Dongguan,China,was simulated by the FLUKA program.The results show that the radiation field of the high energy proton accelerator is dominated by neutron radiation,with a broad range of neutron energies,spanning about eleven orders of magnitude.Simulation and calculation of the response functions of four Bonner spheres with a simplified model is done with FLUKA and MCNPX codes respectively,proving the feasibility of the FLUKA program for this application and the correctness of the calculation method.Using the actual model,we simulate and calculate the energy response functions of Bonner sphere detectors with polyethylene layers of different diameters,including detectors with lead layers,using the FLUKA code.Based on the simulation results,we select eleven detectors as the basic structure for an Extended Range Neutron Multisphere Spectrometer (ERNMS).

  6. Packing Effect of Excluded Volume on Hard-Sphere Colloids

    Institute of Scientific and Technical Information of China (English)

    肖长明; 金国钧; 马余强

    2001-01-01

    We apply the principle of maximum entropy to consider the excluded volume effect on the phase separation of binary mixtures consisting of hard spheres with two different diameters. We show that a critical volume fraction of hard spheres exists locating the packing of large spheres. In particular, through numerical calculation, we have found that the critical volume fraction becomes lower when the ratio α = σ1/σ2 of large-to-small sphere diameters increases, but becomes higher when the ratio of the large sphere volume fraction to the total volume fraction of large and small spheres increases.

  7. The effect of PTSA on preparation of mesophase carbon spheres.

    Directory of Open Access Journals (Sweden)

    Youliang Cheng

    2009-05-01

    Full Text Available Mesophase spheres have been synthesized by heat-treating a medium coal tar pitch at 420 ºC for 2 hours in the presence of P-toluene sulphonic acid (PTSA. The effect of PTSA on synthesis of mesophase spheres had been studied. It was found that PTSA promotes the formation of mesophase spheres in coal tar pitch through acceleratingpolymerization of aromatic hydrocarbons. PTSA content between 3 and 5 wt % gave similar size spheres, beyond which as the PTSA content increases, the size of spheres increases. 5 wt % PTSA gives uniform spheres with small size, good spherical shape and smooth surface.

  8. Spheres: from Ground Development to ISS Operations

    Science.gov (United States)

    Katterhagen, A.

    2016-01-01

    SPHERES (Synchronized Position Hold Engage and Reorient Experimental Satellites) is an internal International Space Station (ISS) Facility that supports multiple investigations for the development of multi-spacecraft and robotic control algorithms. The SPHERES National Lab Facility aboard ISS is managed and operated by NASA Ames Research Center (ARC) at Moffett Field California. The SPHERES Facility on ISS consists of three self-contained eight-inch diameter free-floating satellites which perform the various flight algorithms and serve as a platform to support the integration of experimental hardware. SPHERES has served to mature the adaptability of control algorithms of future formation flight missions in microgravity (6 DOF (Degrees of Freedom) / long duration microgravity), demonstrate key close-proximity formation flight and rendezvous and docking maneuvers, understand fault diagnosis and recovery, improve the field of human telerobotic operation and control, and lessons learned on ISS have significant impact on ground robotics, mapping, localization, and sensing in three-dimensions - among several other areas of study.

  9. Performance and Politics in the Public Sphere

    Directory of Open Access Journals (Sweden)

    Pia Wiegmink

    2011-12-01

    Full Text Available Pia Wiegmink’s timely examination of the transforming transnational spaces of protest in a globalizing and technologically mediated public sphere in “Performance and Politics in the Public Sphere” offers a well-researched review of contemporary theory surrounding ideas of the political (Chantal Mouffe, the public sphere (Jürgen Habermas, the transnational public sphere (Nancy Fraser, and the reterritorialized transnational public sphere (Markus Schroer as the basis for her analysis of how the performance of political action in public—virtual or physical—is transformed by the capacity of the local to be played on a global stage, thus turning the citizen-actor into a cosmopolitan, transnational force. Tracing examples from the Seattle protests against the World Trade Organization meetings in 1999 by the Global Justice Movement to the work of the Electronic Disturbance Theater, from the civil rights movement to the subject matter of her larger study, “The Church of Life After Shopping,” “Billionaires for Bush,” and “The Yes Men,” Wiegmink provides an important analysis of the “alternative aesthetics” of the counterpublics’ formation, dissent, and action in and against hegemony. This selection is taken from her monograph, Protest EnACTed: Activist Performance in the Contemporary United States, a strong, cultural studies–focused contribution to transnational American Studies.

  10. First results of the SPHERE experiment

    Directory of Open Access Journals (Sweden)

    Shaulov Sergey

    2013-06-01

    Full Text Available First results of the balloon-borne experiment SPHERE are presented. The primary spectrum in the energy range 1016 – 5 · 1017 eV is compared with data of other experiments. The primary energies were reconstructed using characteristics of the Vavilov-Cherenkov radiation from extensive air showers, reflected from a snow surface.

  11. 1/4-pinched contact sphere theorem

    DEFF Research Database (Denmark)

    Ge, Jian; Huang, Yang

    2016-01-01

    Given a closed contact 3-manifold with a compatible Riemannian metric, we show that if the sectional curvature is 1/4-pinched, then the contact structure is universally tight. This result improves the Contact Sphere Theorem in [EKM12], where a 4/9-pinching constant was imposed. Some tightness res...

  12. SPHERE ZIMPOL: Overview and performance simulation

    NARCIS (Netherlands)

    Thalmann, C.; Schmid, H.M.; Boccaletti, A.; Mouillet, D.; Dohlen, K.; Roelfsema, R.; Carbillet, M.; Gisler, D.; Beuzit, J.-L.; Feldt, M.; Gratton, R.; Joos, F.; Keller, C.U.; Kragt, J.; Pragt, J.H.; Puget, P.; Rigal, F.; Snik, F.; Waters, R.; Wildi, F.

    2008-01-01

    The ESO planet finder instrument SPHERE will search for the polarimetric signature of the reflected light from extrasolar planets, using a VLT telescope, an extreme AO system (SAXO), a stellar coronagraph, and an imaging polarimeter (ZIMPOL). We present the design concept of the ZIMPOL instrument, a

  13. Casimir stress on lossy magnetodielectric spheres

    CERN Document Server

    Raabe, C; Welsch, D G; Raabe, Christian; Knoell, Ludwig; Welsch, Dirk-Gunnar

    2003-01-01

    An expression for the Casimir stress on arbitrary dispersive and lossy linear magnetodielectric matter at finite temperature, including left-handed material, is derived and applied to spherical systems. To cast the relevant part of the scattering Green tensor for a general magnetodielectric sphere in a convenient form, classical Mie scattering is reformulated.

  14. Ligand sphere conversions in terminal carbide complexes

    DEFF Research Database (Denmark)

    Morsing, Thorbjørn Juul; Reinholdt, Anders; Sauer, Stephan P. A.

    2016-01-01

    Metathesis is introduced as a preparative route to terminal carbide complexes. The chloride ligands of the terminal carbide complex [RuC(Cl)2(PCy3)2] (RuC) can be exchanged, paving the way for a systematic variation of the ligand sphere. A series of substituted complexes, including the first exam...

  15. Performance and Politics in the Public Sphere

    Directory of Open Access Journals (Sweden)

    Pia Wiegmink

    2011-12-01

    Full Text Available Pia Wiegmink’s timely examination of the transforming transnational spaces of protest in a globalizing and technologically mediated public sphere in “Performance and Politics in the Public Sphere” offers a well-researched review of contemporary theory surrounding ideas of the political (Chantal Mouffe, the public sphere (Jürgen Habermas, the transnational public sphere (Nancy Fraser, and the reterritorialized transnational public sphere (Markus Schroer as the basis for her analysis of how the performance of political action in public—virtual or physical—is transformed by the capacity of the local to be played on a global stage, thus turning the citizen-actor into a cosmopolitan, transnational force. Tracing examples from the Seattle protests against the World Trade Organization meetings in 1999 by the Global Justice Movement to the work of the Electronic Disturbance Theater, from the civil rights movement to the subject matter of her larger study, “The Church of Life After Shopping,” “Billionaires for Bush,” and “The Yes Men,” Wiegmink provides an important analysis of the “alternative aesthetics” of the counterpublics’ formation, dissent, and action in and against hegemony. This selection is taken from her monograph, Protest EnACTed: Activist Performance in the Contemporary United States, a strong, cultural studies–focused contribution to transnational American Studies.

  16. The Public Sphere, Globalization and Technological Development

    OpenAIRE

    Tina Sikka

    2006-01-01

    Tina Sikka examines the emergence and transformation of Habermas's theory of the public sphere, looking at how this concept informs the debates around communication technologies in development. Development (2006) 49, 87–93. doi:10.1057/palgrave.development.1100277

  17. Steel Spheres and Skydiver--Terminal Velocity

    Science.gov (United States)

    Costa Leme, J.; Moura, C.; Costa, Cintia

    2009-01-01

    This paper describes the use of open source video analysis software in the study of the relationship between the velocity of falling objects and time. We discuss an experiment in which a steel sphere falls in a container filled with two immiscible liquids. The motion is similar to that of a skydiver falling through air.

  18. Transnational public spheres : A spatial perspective

    NARCIS (Netherlands)

    Forough, Mohammadbagher

    2015-01-01

    Whereas more and more transnational challenges (such as global financial crises, climate change, terrorism, migration, and so forth) are affecting people’s lives, democratic systems and their public spheres (i.e. spaces in which citizens can express their collective concerns) are national. To give a

  19. Production of Liquid Metal Spheres by Molding

    Directory of Open Access Journals (Sweden)

    Mohammed G. Mohammed

    2014-10-01

    Full Text Available This paper demonstrates a molding technique for producing spheres composed of eutectic gallium-indium (EGaIn with diameters ranging from hundreds of microns to a couple millimeters. The technique starts by spreading EGaIn across an elastomeric sheet featuring cylindrical reservoirs defined by replica molding. The metal flows into these features during spreading. The spontaneous formation of a thin oxide layer on the liquid metal keeps the metal flush inside these reservoirs. Subsequent exposure to acid removes the oxide and causes the metal to bead up into a sphere with a size dictated by the volume of the reservoirs. This technique allows for the production and patterning of droplets with a wide range of volumes, from tens of nanoliters up to a few microliters. EGaIn spheres can be embedded or encased subsequently in polymer matrices using this technique. These spheres may be useful as solder bumps, electrodes, thermal contacts or components in microfluidic devices (valves, switches, pumps. The ease of parallel-processing and the ability to control the location of the droplets during their formation distinguishes this technique.

  20. Determinantal point process models on the sphere

    DEFF Research Database (Denmark)

    Møller, Jesper; Nielsen, Morten; Porcu, Emilio

    We consider determinantal point processes on the d-dimensional unit sphere Sd . These are finite point processes exhibiting repulsiveness and with moment properties determined by a certain determinant whose entries are specified by a so-called kernel which we assume is a complex covariance functi...

  1. The Nationalisation of the Domestic Sphere

    NARCIS (Netherlands)

    Storm, H.J.

    2016-01-01

    Banal forms of nationalism permeate our everyday life. However, it is not very clear when all kinds of banal objects and practices became nationalised. In this article, I focus on the domestic sphere by analysing how around 1900 a small group of activists began to propagate the nationalisation of do

  2. Pious Entertainment: Hizbullah's Islamic Cultural Sphere

    NARCIS (Netherlands)

    Alagha, J.E.

    2011-01-01

    Alagha’s chapter on Hezbollah’s Islamic cultural sphere is sure to generate some of the most interesting discussion. Lebanon and Hezbollah in particular are among the hottest topics in the studies of contemporary Islam, but few people actually have the appropriate levels of both access to and unders

  3. Metal-Matrix/Hollow-Ceramic-Sphere Composites

    Science.gov (United States)

    Baker, Dean M.

    2011-01-01

    A family of metal/ceramic composite materials has been developed that are relatively inexpensive, lightweight alternatives to structural materials that are typified by beryllium, aluminum, and graphite/epoxy composites. These metal/ceramic composites were originally intended to replace beryllium (which is toxic and expensive) as a structural material for lightweight mirrors for aerospace applications. These materials also have potential utility in automotive and many other terrestrial applications in which there are requirements for lightweight materials that have high strengths and other tailorable properties as described below. The ceramic component of a material in this family consists of hollow ceramic spheres that have been formulated to be lightweight (0.5 g/cm3) and have high crush strength [40.80 ksi (.276.552 MPa)]. The hollow spheres are coated with a metal to enhance a specific performance . such as shielding against radiation (cosmic rays or x rays) or against electromagnetic interference at radio and lower frequencies, or a material to reduce the coefficient of thermal expansion (CTE) of the final composite material, and/or materials to mitigate any mismatch between the spheres and the matrix metal. Because of the high crush strength of the spheres, the initial composite workpiece can be forged or extruded into a high-strength part. The total time taken in processing from the raw ingredients to a finished part is typically 10 to 14 days depending on machining required.

  4. Experimentation on recurrent sphere collision with Audacity

    Science.gov (United States)

    Muradoglu, Murat; Ng, Enoch Ming Wei; Ng, Tuck Wah

    2014-11-01

    Under the theme of collisions that occur repeatedly, we conducted easy and inexpensive experiments of rebounding spheres and Newton’s cradle with two spheres to determine the coefficients of restitution using the sound record feature in modern laptops and a free and open source software called Audacity. In the rebounding sphere experiment, the coefficients of restitution of the golf and ping pong balls used were found to be 0.727 ± 0.025 and 0.816 ± 0.041 respectively. With the Netwon’s cradle experiment, the coefficient of restitution of two steel sphere balls was found to be 0.987 ± 0.003. The contrasts in the results obtained from both experiments permit the operational principles of a pendulum to be emphasized, and engagements to be made to consider the transfer of kinetic energy in the form of vibrational energy of the bodies’ constituents. Using a one-dimensional two-mass model with spring and damper linkages to account for harmonic motions that occur during impact, we found it possible to perform a simple analysis to account for this, and how it can be linked to high energy transfer modes such as the phenomenon of resonance and impedance matching.

  5. Hollow silica spheres: synthesis and mechanical properties.

    Science.gov (United States)

    Zhang, Lijuan; D'Acunzi, Maria; Kappl, Michael; Auernhammer, Günter K; Vollmer, Doris; van Kats, Carlos M; van Blaaderen, Alfons

    2009-03-03

    Core-shell polystyrene-silica spheres with diameters of 800 nm and 1.9 microm were synthesized by soap-free emulsion and dispersion polymerization of the polystyrene core, respectively. The polystyrene spheres were used as templates for the synthesis of silica shells of tunable thickness employing the Stöber method [Graf et al. Langmuir 2003, 19, 6693]. The polystyrene template was removed by thermal decomposition at 500 degrees C, resulting in smooth silica shells of well-defined thickness (15-70 nm). The elastic response of these hollow spheres was probed by atomic force microscopy (AFM). A point load was applied to the particle surface through a sharp AFM tip, and successively increased until the shell broke. In agreement with the predictions of shell theory, for small deformations the deformation increased linearly with applied force. The Young's modulus (18 +/- 6 GPa) was about 4 times smaller than that of fused silica [Adachi and Sakka J. Mater. Sci. 1990, 25, 4732] but identical to that of bulk silica spheres (800 nm) synthesized by the Stöber method, indicating that it yields silica of lower density. The minimum force needed to irreversibly deform (buckle) the shell increased quadratically with shell thickness.

  6. Measurement of the neutron spectrum by the multi-sphere method using a BF3 counter

    Directory of Open Access Journals (Sweden)

    Khabaz Rahim

    2011-01-01

    Full Text Available The multi-sphere method, a neutron detection technique, has been improved with a BF3 long cylindrical counter as a thermal detector located in the center of seven spheres with a diameter range of 3.5 to 12 inches. Energy response functions of the system have been determined by applying the MCNP4C Monte Carlo code of 10-8 MeV to 18 MeV. A new shadow cone has been designed to account for scattered neutrons. Although the newly designed shadow cone is smaller in length, its attenuation coefficient has been improved. To evaluate the system, the neutron spectrum of a 241AM-Be source has been measured.

  7. Full sphere hydrodynamic and dynamo benchmarks

    KAUST Repository

    Marti, P.

    2014-01-26

    Convection in planetary cores can generate fluid flow and magnetic fields, and a number of sophisticated codes exist to simulate the dynamic behaviour of such systems. We report on the first community activity to compare numerical results of computer codes designed to calculate fluid flow within a whole sphere. The flows are incompressible and rapidly rotating and the forcing of the flow is either due to thermal convection or due to moving boundaries. All problems defined have solutions that alloweasy comparison, since they are either steady, slowly drifting or perfectly periodic. The first two benchmarks are defined based on uniform internal heating within the sphere under the Boussinesq approximation with boundary conditions that are uniform in temperature and stress-free for the flow. Benchmark 1 is purely hydrodynamic, and has a drifting solution. Benchmark 2 is a magnetohydrodynamic benchmark that can generate oscillatory, purely periodic, flows and magnetic fields. In contrast, Benchmark 3 is a hydrodynamic rotating bubble benchmark using no slip boundary conditions that has a stationary solution. Results from a variety of types of code are reported, including codes that are fully spectral (based on spherical harmonic expansions in angular coordinates and polynomial expansions in radius), mixed spectral and finite difference, finite volume, finite element and also a mixed Fourier-finite element code. There is good agreement between codes. It is found that in Benchmarks 1 and 2, the approximation of a whole sphere problem by a domain that is a spherical shell (a sphere possessing an inner core) does not represent an adequate approximation to the system, since the results differ from whole sphere results. © The Authors 2014. Published by Oxford University Press on behalf of The Royal Astronomical Society.

  8. Radiation of non-relativistic particle on a conducting sphere and a string of spheres

    CERN Document Server

    Shul'ga, N F; Larikova, E A

    2016-01-01

    The radiation arising under uniform motion of non-relativistic charged particle by (or through) perfectly conducting sphere is considered. The rigorous results are obtained using the method of images known from electrostatics.

  9. VMware vSphere PowerCLI Reference Automating vSphere Administration

    CERN Document Server

    Dekens, Luc; Sizemore, Glenn; van Lieshout, Arnim; Medd, Jonathan

    2011-01-01

    Your One-Stop Reference for VMware vSphere Automation If you manage vSphere in a Windows environment, automating routine tasks can save you time and increase efficiency. VMware vSphere PowerCLI is a set of pre-built commands based on Windows PowerShell that is designed to help you automate vSphere processes involving virtual machines, datacenters, storage, networks, and more. This detailed guide-using a practical, task-based approach and real-world examples-shows you how to get the most out of PowerCLI's handy cmdlets. Learn how to: Automate vCenter Server and ESX/ESX(i) Server deployment and

  10. Revitalization of the Public Sphere: A Comparison between Habermasian and the New Public Sphere

    Directory of Open Access Journals (Sweden)

    Muhammad Zubair Khan

    2014-06-01

    Full Text Available “Public sphere” is an important component of modern polity. Civil society brings the state in touch with the needs of the citizens through the medium of public sphere. However, Habermas argues that “public sphere” experienced refeudalization owing to various factors i.e. propaganda, cultural industry, market and state intervention. The “public” was condemned to be mere spectator again. This article argues that modern technologies enabled new public sphere (NPS can help restore public status as participant in the democratic process. By employing interpretivist approach the article compares the Habermasian ideal of public sphere with NPS and constructs a matrix, depicting the various related aspects between the two models for highlighting the revival of the public sphere.

  11. CLIC Detector Power Requirements

    CERN Document Server

    Gaddi, A

    2013-01-01

    An estimate for the CLIC detector power requirements is outlined starting from the available data on power consumptions of the four LHC experiments and considering the differences between a typical LHC Detector (CMS) and the CLIC baseline detector concept. In particular the impact of the power pulsing scheme for the CLIC Detector electronics on the overall detector consumption is considered. The document will be updated with the requirements of the sub-detector electronics once they are more defined.

  12. Pixel Vertex Detectors

    OpenAIRE

    Wermes, Norbert

    2006-01-01

    Pixel vertex detectors are THE instrument of choice for the tracking of charged particles close to the interaction point at the LHC. Hybrid pixel detectors, in which sensor and read-out IC are separate entities, constitute the present state of the art in detector technology. Three of the LHC detectors use vertex detectors based on this technology. A development period of almost 10 years has resulted in pixel detector modules which can stand the extreme rate and timing requirements as well as ...

  13. Revitalization of the Public Sphere: A Comparison between Habermasian and the New Public Sphere

    OpenAIRE

    2014-01-01

    “Public sphere” is an important component of modern polity. Civil society brings the state in touch with the needs of the citizens through the medium of public sphere. However, Habermas argues that “public sphere” experienced refeudalization owing to various factors i.e. propaganda, cultural industry, market and state intervention. The “public” was condemned to be mere spectator again. This article argues that modern technologies enabled new public sphere (NPS) can help restore ...

  14. Cavity formation by the impact of Leidenfrost spheres

    KAUST Repository

    Marston, Jeremy

    2012-05-01

    We report observations of cavity formation and subsequent collapse when a heated sphere impacts onto a liquid pool. When the sphere temperature is much greater than the boiling point of the liquid, we observe an inverted Leidenfrost effect where the sphere is encompassed by a vapour layer that prevents physical contact with the liquid. This creates the ultimate non-wetting scenario during sphere penetration through a free surface, producing very smooth cavity walls. In some cases during initial entry, however, the liquid contacts the sphere at the equator, leading to the formation of a dual cavity structure. For cold sphere impacts, where a contact line is observed, we reveal details of the contact line pinning, which initially forms a sawtooth pattern. We also observe surface waves on the cavity interface for cold spheres. We compare our experimental results to previous studies of cavity dynamics and, in particular, the influence of hydrophobicity on the entry of the sphere. © 2012 Cambridge University Press.

  15. MUON DETECTOR

    CERN Multimedia

    F. Gasparini

    DT As announced in the previous Bulletin MU DT completed the installation of the vertical chambers of barrel wheels 0, +1 and +2. 242 DT and RPC stations are now installed in the negative barrel wheels. The missing 8 (4 in YB-1 and 4 in YB-2) chambers can be installed only after the lowering of the two wheels into the UX cavern, which is planned for the last quarter of the year. Cabling on the surface of the negative wheels was finished in May after some difficulties with RPC cables. The next step was to begin the final commissioning of the wheels with the final trigger and readout electronics. Priority was giv¬en to YB0 in order to check everything before the chambers were covered by cables and services of the inner detectors. Commissioning is not easy since it requires both activity on the central and positive wheels underground, as well as on the negative wheels still on the surface. The DT community is requested to commission the negative wheels on surface to cope with a possible lack of time a...

  16. Ultrasonic beam-plotting with very small spheres.

    Science.gov (United States)

    Round, W H; Swan, H

    1991-12-01

    A method of pulse-echo ultrasonic beam plotting is described. It differs from traditional pulse-echo beam plotting in that the ultrasonic pulses are scattered off a totally isolated sphere rather than a sphere suspended on a wire. The method also allows extremely small spheres to be used thus providing greater resolution. It is demonstrated that pulse-echo beam plotting using spheres of different size produces different iso-echo amplitude curves.

  17. On Vassiliev invariants of braid groups of the sphere

    CERN Document Server

    Kaabi, N

    2012-01-01

    We construct a universal Vassiliev invariant for braid groups of the sphere and the mapping class groups of the sphere with $n$ punctures. The case of a sphere is different from the classical braid groups or braids of oriented surfaces of genus strictly greater than zero, since Vassiliev invariants in a group without 2-torsion do not distinguish elements of braid group of a sphere.

  18. Self-lensing of a Singular Isothermal Sphere

    OpenAIRE

    Wang, Yun

    1999-01-01

    Many astrophysical systems can be approximated as isothermal spheres. In an isothermal sphere, the ``foreground'' objects can act as lenses on ``background'' objects in the same distribution. We study gravitational lensing by a singular isothermal sphere analytically. Our results may have interesting applications.

  19. 21 CFR 886.3320 - Eye sphere implant.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Eye sphere implant. 886.3320 Section 886.3320 Food... DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3320 Eye sphere implant. (a) Identification. An eye sphere implant is a device intended to be implanted in the eyeball to occupy space following the...

  20. Quantitative comparison using generalized relative object detectability (G-ROD) metrics of an amorphous selenium detector with high resolution microangiographic fluoroscopes (MAF) and standard flat panel detectors (FPD)

    Science.gov (United States)

    Russ, M.; Shankar, A.; Jain, A.; Setlur Nagesh, S. V.; Ionita, C. N.; Scott, C.; Karim, K. S.; Bednarek, D. R.; Rudin, S.

    2016-03-01

    A novel amorphous selenium (a-Se) direct detector with CMOS readout has been designed, and relative detector performance investigated. The detector features include a 25μm pixel pitch, and 1000μm thick a-Se layer operating at 10V/μm bias field. A simulated detector DQE was determined, and used in comparative calculations of the Relative Object Detectability (ROD) family of prewhitening matched-filter (PWMF) observer and non-pre-whitening matched filter (NPWMF) observer model metrics to gauge a-Se detector performance against existing high resolution micro-angiographic fluoroscopic (MAF) detectors and a standard flat panel detector (FPD). The PWMF-ROD or ROD metric compares two x-ray imaging detectors in their relative abilities in imaging a given object by taking the integral over spatial frequencies of the Fourier transform of the detector DQE weighted by an object function, divided by the comparable integral for a different detector. The generalized-ROD (G-ROD) metric incorporates clinically relevant parameters (focal- spot size, magnification, and scatter) to show the degradation in imaging performance for detectors that are part of an imaging chain. Preliminary ROD calculations using simulated spheres as the object predicted superior imaging performance by the a-Se detector as compared to existing detectors. New PWMF-G-ROD and NPWMF-G-ROD results still indicate better performance by the a-Se detector in an imaging chain over all sphere sizes for various focal spot sizes and magnifications, although a-Se performance advantages were degraded by focal spot blurring. Nevertheless, the a-Se technology has great potential to provide break- through abilities such as visualization of fine details including of neuro-vascular perforator vessels and of small vascular devices.

  1. An integrating sphere radiometer as a solution for high power calibrations in fibre optics

    Science.gov (United States)

    Carrasco-Sanz, Ana; Rodríguez-Barrios, Félix; Corredera, Pedro; Martín-López, Sonia; González-Herráez, Miguel; Hernanz, María Luisa

    2006-04-01

    This paper describes the design, characterization and calibration of a high power transfer standard for optical power measurements in optical fibres based on an integrating sphere radiometer. This radiometer, based on two detectors (Si and InGaAs), can measure powers between 100 nW and 10 W within the wavelength range of (400-1700) nm. The radiometer has been calibrated over the total spectral range of use against an electrically calibrated pyroelectric radiometer and different fibre laser diodes and ion lasers. The total uncertainty obtained is lower than ±1.5% for these wavelengths and power ranges (excluding the water absorption region).

  2. THE SPECTRUM OF COMPACT HYPERSURFACE IN SPHERE

    Institute of Scientific and Technical Information of China (English)

    Xu Senlin; Deng Qintao; Chen Dongmei

    2004-01-01

    Let M be a compact minimal hypersurface of sphere Sn+1(1). Let (M) be H (r)-torus of sphere Sn+ 1 (1).Assume they have the same constant mean curvature H, the result in [1] is that ifSpec0(M, g) =Spec0((M), g),then for 3≤ n ≤ 6, r2≤n-1/n or n ≥ 6, r2 ≥ n-1, then M is isometric to (M). We improved the result and prove that: if Spec0(M,g) =Spec0((M),g), then M is isometric to (M). Generally, if Specp(M,g) =Specp((M),g), here p is fixed and satisfies that n(n - 1) ≠ 6p(n - p), then M is isometric to (M).

  3. Event Driven Langevin simulations of Hard Spheres

    CERN Document Server

    Scala, Antonio

    2011-01-01

    The blossoming of interest in colloids and nano-particles has given renewed impulse to the study of hard-body systems. In particular, hard spheres have become a real test system for theories and experiments. It is therefore necessary to study the complex dynamics of such systems in presence of a solvent; disregarding hydrodynamic interactions, the simplest model is the Langevin equation. Unfortunately, standard algorithms for the numerical integration of the Langevin equation require that interactions are slowly varying during an integration timestep. This in not the case for hard-body systems, where there is no clearcut between the correlation time of the noise and the timescale of the interactions. Starting first from a splitting of the Fokker-Plank operator associated with the Langevin dynamics, and then from an approximation of the two-body Green's function, we introduce and test two new algorithms for the simulation of the Langevin dynamics of hard-spheres.

  4. Electromagnetic Scattering by Spheres of Topological Insulators

    CERN Document Server

    Ge, Lixin; Zi, Jian

    2015-01-01

    The electromagnetic scattering properties of topological insulator (TI) spheres are systematically studied in this paper. Unconventional backward scattering caused by the topological magneto-electric (TME) effect of TIs are found in both Rayleigh and Mie scattering regimes. This enhanced backward scattering can be achieved by introducing an impedance-matched background which can suppress the bulk scattering. For the cross-polarized scattering coefficients, interesting antiresonances are found in the Mie scattering regime, wherein the cross-polarized electromagnetic fields induced by the TME effect are trapped inside TI spheres. In the Rayleigh limit, the quantized TME effect of TIs can be determined by measuring the electric-field components of scattered waves in the far field.

  5. Theory of tectonics in the sphere

    CERN Document Server

    Ribeiro, A; Taborda, R; Ribeiro, Antonio; Matias, Luis; Taborda, Rui

    2005-01-01

    Soft or Deformable Plate Tectonics in the sphere must follow geometric rules inferred from the orthographic projection. An analytic equivalent of this geometry can be derived by the application of Potential Field Methods in the case of Atlantic type oceans. Laplace equation must be obeyed by the velocity field between the ridge and the passive margin if we neglect the very slight compressibility of ocean lithosphere. A strain wave propagates in the sphere analogous to the behaviour of a free harmonic oscillator. Combining zonal harmonics of order one and sectorial harmonics of degree one we obtain a tesseral harmonic equivalent to the orthographic solution. This potential field approach is valid for homogeneous deformation regime in oceanic lithosphere. Above a compression threshold of 5 to 10% buckling and simultaneous faulting occurs. In Pacific type oceans a dynamic approach, similar to a forced oscillation, must be applied because there are sinks in subduction zones.

  6. Entanglement entropy for the n-sphere

    CERN Document Server

    Casini, H

    2010-01-01

    We calculate the entanglement entropy for a sphere and a massless scalar field in any dimensions. The reduced density matrix is expressed in terms of the infinitesimal generator of conformal transformations keeping the sphere fixed. The problem is mapped to the one of a thermal gas in a hyperbolic space and solved by the heat kernel approach. The coefficient of the logarithmic term in the entropy for 2 and 4 spacetime dimensions are in accordance with previous numerical and analytical results. In particular, the four dimensional result, together with the one reported by Solodukhin, gives support to the Ryu-Takayanagi holographic anzats. We also find there is no logarithmic contribution to the entropy for odd space time dimensions.

  7. Packing circles and spheres on surfaces

    KAUST Repository

    Schiftner, Alexander

    2009-12-01

    Inspired by freeform designs in architecture which involve circles and spheres, we introduce a new kind of triangle mesh whose faces\\' incircles form a packing. As it turns out, such meshes have a rich geometry and allow us to cover surfaces with circle patterns, sphere packings, approximate circle packings, hexagonal meshes which carry a torsion-free support structure, hybrid tri-hex meshes, and others. We show how triangle meshes can be optimized so as to have the incircle packing property. We explain their relation to conformal geometry and implications on solvability of optimization. The examples we give confirm that this kind of meshes is a rich source of geometric structures relevant to architectural geometry.

  8. Second-Generation Curvelets on the Sphere

    CERN Document Server

    Chan, Jennifer Y H; Kitching, Thomas D; McEwen, Jason D

    2015-01-01

    Curvelets are efficient to represent highly anisotropic signal content, such as local linear and curvilinear structure. First-generation curvelets on the sphere, however, suffered from blocking artefacts. We present a new second- generation curvelet transform, where scale-discretised curvelets are constructed directly on the sphere. Scale-discretised curvelets exhibit a parabolic scaling relation, are well-localised in both spatial and harmonic domains, support the exact analysis and synthesis of both scalar and spin signals, and are free of blocking artefacts. We present fast algorithms to compute the exact curvelet transform, reducing computational complexity from $\\mathcal{O}(L^5)$ to $\\mathcal{O}(L^3\\log_{2}{L})$ for signals band-limited at $L$. The implementation of these algorithms is made publicly available. Finally, we present an illustrative application demonstrating the effectiveness of curvelets for representing directional curve-like features in natural spherical images.

  9. Packing circles and spheres on surfaces

    KAUST Repository

    Schiftner, Alexander

    2009-01-01

    Inspired by freeform designs in architecture which involve circles and spheres, we introduce a new kind of triangle mesh whose faces\\' incircles form a packing. As it turns out, such meshes have a rich geometry and allow us to cover surfaces with circle patterns, sphere packings, approximate circle packings, hexagonal meshes which carry a torsion-free support structure, hybrid tri-hex meshes, and others. We show how triangle meshes can be optimized so as to have the incircle packing property. We explain their relation to conformal geometry and implications on solvability of optimization. The examples we give confirm that this kind of meshes is a rich source of geometric structures relevant to architectural geometry. © 2009 ACM.

  10. Criticality of a {sup 237}Np Sphere

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Rene G.; Hayes, David K.; Cappiello, Charlene C.; Myers, William L.; Jaegers, Peter J.; Clement, Steven D.

    2003-07-22

    A critical mass experiment using a 6-kg {sup 237}Np sphere has been performed. The purpose of the experiment is to get a better estimate of the critical mass of {sup 237}Np. To attain criticality, the {sup 237}Np sphere was surrounded with 93 wt % {sup 235}U shells. A 1/M as a function of uranium mass was performed. An MCNP neutron transport code was used to model the experiment. The MCNP code yielded a k{sub eff} of 0.99089 {+-} 0.0003 compared with a k{sub eff} 1.0026 for the experiment. Based on these results, it is estimated that the critical mass of {sup 237}Np ranges from kilogram weights in the high fifties to low sixties.

  11. Nineteenth Century Public And Private Spheres

    Directory of Open Access Journals (Sweden)

    SIMA REMINA

    2014-12-01

    Full Text Available The aim of this paper is to illustrate the public and private spheres. The former represents the area in which each of us carries out their daily activities, while the latter is mirrored by the home. Kate Chopin and Charlotte Perkins Gilman are two salient nineteenth-century writers who shape the everyday life of the historical period they lived in, within their literary works that shed light on the areas under discussion.

  12. Supersymmetric theories on squashed five-sphere

    CERN Document Server

    Imamura, Yosuke

    2012-01-01

    We construct supersymmetric theories on the SU(3)xU(1) symmetric squashed five-sphere with 2, 4, 6, and 12 supercharges. We first determine the Killing equation by dimensional reduction from 6d, and use Noether procedure to construct actions. The supersymmetric Yang-Mills action is straightforwardly obtained from the supersymmetric Chern-Simons action by using a supersymmetry preserving constant vector multiplet.

  13. Lp CONVERGENCE OF CESARO MEANS ON SPHERE

    Institute of Scientific and Technical Information of China (English)

    Dai Feng; Zhang Xirong

    2000-01-01

    Let Rnbe n-dimensional Euclidean space with n≤3. Denote by Ωn the unit sphere in Rn. For f ∈ L(Ωn) ve denote by σNo (f) its Cesaro means of order δ for spherical harmonic expansions. The special value λ= 2λ n-2 of δ is knowm as the critical one. For 0<δ≤λ, we set P0=2 λ/δ+λ

  14. Locating a circle on a sphere

    DEFF Research Database (Denmark)

    Brimberg, Jack; Juel, Henrik; Schöbel, Anita

    2003-01-01

    We consider the problem of locating a spherical circle with respect to existing facilities on a sphere, such that the sum of weighted distances between the circle and the facilities is minimized, or such that the maximum weighted distance is minimized. The problem properties are analyzed, and we...... give solution procedures. When the circle to be located is restricted to be a great circle, some simplifications are possible....

  15. On the revolution of heavenly spheres

    CERN Document Server

    Copernicus, Nicolaus

    1995-01-01

    The Ptolemaic system of the universe, with the earth at the center, had held sway since antiquity as authoritative in philosophy, science, and church teaching. Following his observations of the heavenly bodies, Nicolaus Copernicus (1473-1543) abandoned the geocentric system for a heliocentric model, with the sun at the center. His remarkable work, On the Revolutions of Heavenly Spheres, stands as one of the greatest intellectual revolutions of all time, and profoundly influenced, among others, Galileo and Sir Isaac Newton.

  16. Stable Stationary Harmonic Maps to Spheres

    Institute of Scientific and Technical Information of China (English)

    Fang Hua LIN; Chang You WANG

    2006-01-01

    For k ≥ 3, we establish new estimate on Hausdorff dimensions of the singular set of stable-stationary harmonic maps to the sphere Sk. We show that the singular set of stable-stationary harmonic maps from B5 to S3 is the union of finitely many isolated singular points and finitely many Holder continuous curves. We also discuss the minimization problem among continuous maps from Bn to S2.

  17. Poincar\\'e Sphere and Decoherence Problems

    CERN Document Server

    Kim, Y S

    2012-01-01

    Henri Poincar\\'e formulated the mathematics of the Lorentz transformations, known as the Poincar\\'e group. He also formulated the Poincar\\'e sphere for polarization optics. It is shown that these two mathematical instruments can be combined into one mathematical device which can address the internal space-time symmetries of elementary particles, decoherence problems in polarization optics, entropy problems, and Feynman's rest of the universe.

  18. Soft-sphere model for liquid metals

    Energy Technology Data Exchange (ETDEWEB)

    Young, D.A.

    1977-11-08

    A semi-empirical soft-sphere model of fluids is modified for application to the thermodynamic properties of liquid metals. Enthalpy, volume, and sound speed are computed as functions of temperature for 13 metals and compared with experimental data. Critical points and coexistence curves are also computed and compared with experimental data, where these have been measured. Strengths and weaknesses of the model are discussed.

  19. Collapse of three on a sphere

    Energy Technology Data Exchange (ETDEWEB)

    Kidambi, R.; Newton, P.K. [Southern California Univ., Los Angeles (United States). Dept. of Aerospace Engineering, Center for Applied Mathematical Sciences

    1999-12-01

    The self-similar collapse of three vortices moving on the surface of a sphere of radius R is analysed and compared with known results of critical literature. Formulas for the collapsing trajectories are derived and compared with the planar formulas. The Hamiltonian system is derived governing the vortex motion. In this projected plane, the solutions are not self-similar. In the last section, the collapse process is studied using tri-linear coordinates, which reduces the system to a planar one.

  20. A property of the bidimensional sphere

    CERN Document Server

    Cavachi, Marius

    2011-01-01

    It is natural to ask for a reasonable constant k having the property that any open set of area greater than k on a bidimensional sphere of area 1 always contains the vertices of a regular tetrahedron. We shall prove that it is sufficient to take k=3/4. In fact we shall prove a more general result. The interested reader will not have any problem in establishing that 3/4 is the best constant with this property.

  1. The Internet And The Public Sphere

    OpenAIRE

    Kürşat, Fide; Özad, Bahire Efe

    2005-01-01

    Habermas (1989) proposes a ‘public sphere’, a setting where people talk freely on the public issues. In his early works, Habermas was rather pessimistic about the provision of the public sphere; however, soon after the introduction of the Internet as an ultimately decentralized medium, in his later work, Habermas (1996) seems more optimistic about the Internet as the provider of the ‘public sphere’. The Internet which is particularly popular among the young people, not only pro...

  2. Effects of confinement on a rotating sphere

    Science.gov (United States)

    Liu, Qianlong; Prosperetti, Andrea

    2009-11-01

    The hydrodynamic force and couple acting on a rotating sphere in a quiescent fluid are modified by nearby boundaries with possible consequences on spin-up and spin-down times of particles uspended in a fluid, their wall deposition, entraiment and others. Up to now, the vast majority of papers dealing with these problems have considered the low-Reynolds-number regime. This paper focuses on the effect of inertia on the hydrodynamic interaction of a spinning sphere with nearby boundaries. Rotation axes parallel and perpendicular to a plane boundary as well as other situations are studied. Several steady and transient numerical results are presented and interptreted in terms of physical scaling arguments. The Navier-Stokes equations for an incompressible, constant-property Newtonian fluid are solved by the finite-difference PHYSALIS method. Among the noteworthy features of this method are the fact that the no-slip condition at the particle surface is satisfied exactly and that the force and torque on the sphere are obtained directly as a by-product of the computation. This feature avoids the need to integrate the stress over the particle surface, which with other methods is a step prone to numerical inaccuracies. A locally refined mesh surrounding the particle is used to enhance the resolution of boundary layers maintaining a manageable overall computational cost.

  3. Willmore Spheres in Compact Riemannian Manifolds

    CERN Document Server

    Mondino, Andrea

    2012-01-01

    The paper is devoted to the variational analysis of the Willmore, and other L^2 curvature functionals, among immersions of 2-dimensional surfaces into a compact riemannian m-manifold (M^m,h) with m>2. The goal of the paper is twofold, on one hand, we give the right setting for doing the calculus of variations (including min max methods) of such functionals for immersions into manifolds and, on the other hand, we prove existence results for possibly branched Willmore spheres under various constraints (prescribed homotopy class, prescribed area) or under curvature assumptions for M^m. To this aim, using the integrability by compensation, we develop first the regularity theory for the critical points of such functionals. We then prove a rigidity theorem concerning the relation between CMC and Willmore spheres. Then we prove that, for every non null 2-homotopy class, there exists a representative given by a Lipschitz map from the 2-sphere into M^m realizing a connected family of conformal smooth (possibly branche...

  4. Comparison of advanced gravitational-wave detectors

    CERN Document Server

    Harry, G M; Strain, K A; Harry, Gregory M; Houser, Janet L; Strain, Kenneth A

    2002-01-01

    We compare two advanced designs for gravitational-wave antennas in terms of their ability to detect two possible gravitational wave sources. Spherical, resonant mass antennas and interferometers incorporating resonant sideband extraction (RSE) were modeled using experimentally measurable parameters. The signal-to-noise ratio of each detector for a binary neutron star system and a rapidly rotating stellar core were calculated. For a range of plausible parameters we found that the advanced LIGO interferometer incorporating RSE gave higher signal-to-noise ratios than a spherical detector resonant at the same frequency for both sources. Spheres were found to be sensitive to these sources at distances beyond our galaxy. Interferometers were sensitive to these sources at far enough distances that several events per year would be expected.

  5. Past, present and future of the Resonant-Mass gravitational wave detectors

    Institute of Scientific and Technical Information of China (English)

    Odylio Denys Aguiar

    2011-01-01

    Resonant-mass gravitational wave detectors are reviewed from the concept of gravitational waves and its mathematical derivation, using Einstein's general relativity, to the present status of bars and spherical detectors, and their prospects for the future, which include dual detectors and spheres with non-resonant transducers. The review not only covers technical aspects of detectors and sciences that will be done,but also analyzes the subject in a historical perspective, covering the various detection efforts over four decades, starting from Weber's pioneering work.

  6. Confined disordered strictly jammed binary sphere packings

    Science.gov (United States)

    Chen, D.; Torquato, S.

    2015-12-01

    Disordered jammed packings under confinement have received considerably less attention than their bulk counterparts and yet arise in a variety of practical situations. In this work, we study binary sphere packings that are confined between two parallel hard planes and generalize the Torquato-Jiao (TJ) sequential linear programming algorithm [Phys. Rev. E 82, 061302 (2010), 10.1103/PhysRevE.82.061302] to obtain putative maximally random jammed (MRJ) packings that are exactly isostatic with high fidelity over a large range of plane separation distances H , small to large sphere radius ratio α , and small sphere relative concentration x . We find that packing characteristics can be substantially different from their bulk analogs, which is due to what we term "confinement frustration." Rattlers in confined packings are generally more prevalent than those in their bulk counterparts. We observe that packing fraction, rattler fraction, and degree of disorder of MRJ packings generally increase with H , though exceptions exist. Discontinuities in the packing characteristics as H varies in the vicinity of certain values of H are due to associated discontinuous transitions between different jammed states. When the plane separation distance is on the order of two large-sphere diameters or less, the packings exhibit salient two-dimensional features; when the plane separation distance exceeds about 30 large-sphere diameters, the packings approach three-dimensional bulk packings. As the size contrast increases (as α decreases), the rattler fraction dramatically increases due to what we call "size-disparity" frustration. We find that at intermediate α and when x is about 0.5 (50-50 mixture), the disorder of packings is maximized, as measured by an order metric ψ that is based on the number density fluctuations in the direction perpendicular to the hard walls. We also apply the local volume-fraction variance στ2(R ) to characterize confined packings and find that these

  7. Preparation and antibacterial activities of hollow silica-Ag spheres.

    Science.gov (United States)

    Lin, Lin; Zhang, Haifang; Cui, Haiying; Xu, Mingqiang; Cao, Shunsheng; Zheng, Guanghong; Dong, Mingdong

    2013-01-01

    Hollow silica spheres with round mesoporous shells were synthesized by core-shell template method, using monodispersed cationic polystyrene particles as core, and TEOS (tetraethoxysilane) as the silica source to form shell. After calcination at 550°C, uniform spheres with a thin shell of silica and hollow interior structures. Transmission electron microscopy results showed that the size of the spheres is about 700 nm in diameter with narrow distribution. In addition, the spheres have a high surface area of 183 m(2)/g. The spheres were subsequently used as silver-loading substrates and the silver loaded spheres were tested in antimicrobial study against gram negative bacteria Eschrichia coli in vitro. The hollow silica-Ag spheres proved significantly higher antibacterial efficacy against E. coli as compared to that of the common silica-Ag particles.

  8. Liquid bridge force between two unequal-sized spheres or a sphere and a plane

    Institute of Scientific and Technical Information of China (English)

    You chuan Chen; Yong zhi Zhao; Hong li Gao; Jin yang Zheng

    2011-01-01

    Liquid bridge force acting between wet particles is an important property in particle characterization.This paper deals with liquid bridge force between either two unequal-sized spherical particles or a sphere and a flat plate under conditions where gravitational effect arising from bridge distortion is negligible.In order to calculate the force of the liquid bridge efficiently and accurately,expressions of liquid configuration and liquid bridge force were derived by building a mechanical model,which assumes the liquid bridge to be circular in shape between either two unequal-sized spheres or a sphere and a plane.To assess the accuracy of the numerical results of the calculated liquid bridge forces,they were compared to the published experimental data.

  9. Uniform Fe3O4-PANi/PS composite spheres with conductive and magnetic properties and their hollow spheres

    Science.gov (United States)

    Wang, Xiaocong; Tang, Saide; Liu, Jing; He, Ziqiong; An, Lijuan; Zhang, Chenxi; Hao, Jingmei; Feng, Wei

    2009-05-01

    Core-shell multifunctional composite spheres consisting of Fe3O4-polyaniline (PANi) shell and polystyrene (PS) core were fabricated using core-shell-structured sulfonated PS spheres (with uniform diameter of 250 nm) as templates. PANi was doped in situ by sulfonic acid resulting the composite spheres are well conductive. Dissolved with solvent, PS cores were removed from the core-shell composite spheres and hollow Fe3O4-PANi spheres were obtained. Removing the PANi and PS components by calcinations produced hollow Fe3O4 spheres. The cavity size of the hollow spheres was uniformly approximate to 190 nm and the shell thickness was 30 nm. The cavity size and the shell thickness can be synchronously controlled by varying the sulfonation time of the PS templates. The shell thickness in size range was of 20-86 nm when the sulfonation time was changed from 1 to 4 h. These resulting spheres could be arranged in order by self-assembly of the templates. Both the Fe3O4-PANi/PS composite spheres and the hollow Fe3O4 spheres exhibit a super-paramagnetic behavior. Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray powder scattering were used to characterize these as-prepared spheres.

  10. Electromagnetic-scattering by bi-sphere groups and coherent-beam scattering by homogeneous spheres

    Institute of Scientific and Technical Information of China (English)

    Linsheng LIU; Hengyu KE; Zhensen WU; Lu BAI

    2008-01-01

    By using Mie's theory, the boundary condi-tions, and some advanced mathematical knowledge, the scattering problem of a plane-wave by bi-sphere groups and of cores-traversed coherent Gauss-beams by one sphere was addressed. In each, the coefficients of the scattering-field expressions were deduced. Finally, the result was predigested and transfigured so that the available form for programming was achieved. On deducing, the former adopted the undetermined coeffi-cient method and the latter used the plane geometry method. Moreover, the complexity of the calculation was decreased here.

  11. Diagnosis of a Poorly Performing Liquid Hydrogen Bulk Storage Sphere

    Science.gov (United States)

    Krenn, Angela G.

    2011-01-01

    There are two 850,000 gallon Liquid Hydrogen (LH2) storage spheres used to support the Space Shuttle Program; one residing at Launch Pad A and the other at Launch Pad B. The LH2 Sphere at Pad B has had a high boiloff rate since being brought into service in the 1960's. The daily commodity loss was estimated to be approximately double that of the Pad A sphere, and well above the minimum required by the sphere's specification. Additionally, after being re-painted in the late 1990's a "cold spot" appeared on the outer sphere which resulted in a poor paint bond, and mold formation. Thermography was used to characterize the area, and the boiloff rate was continually evaluated. All evidence suggested that the high boiloff rate was caused by an excessive heat leak into the inner sphere due to an insulation void in the annulus. Pad B was recently taken out of Space Shuttle program service which provided a unique opportunity to diagnose the sphere's poor performance. The sphere was drained and inerted, and then opened from the annular relief device on the top where a series of boroscoping operations were accomplished. Boroscoping revealed a large Perlite insulation void in the region of the sphere where the cold spot was apparent. Perlite was then trucked in and off-loaded into the annular void region until the annulus was full. The sphere has not yet been brought back into service.

  12. Zinc coordination spheres in protein structures.

    Science.gov (United States)

    Laitaoja, Mikko; Valjakka, Jarkko; Jänis, Janne

    2013-10-07

    Zinc metalloproteins are one of the most abundant and structurally diverse proteins in nature. In these proteins, the Zn(II) ion possesses a multifunctional role as it stabilizes the fold of small zinc fingers, catalyzes essential reactions in enzymes of all six classes, or assists in the formation of biological oligomers. Previously, a number of database surveys have been conducted on zinc proteins to gain broader insights into their rich coordination chemistry. However, many of these surveys suffer from severe flaws and misinterpretations or are otherwise limited. To provide a more comprehensive, up-to-date picture on zinc coordination environments in proteins, zinc containing protein structures deposited in the Protein Data Bank (PDB) were analyzed in detail. A statistical analysis in terms of zinc coordinating amino acids, metal-to-ligand bond lengths, coordination number, and structural classification was performed, revealing coordination spheres from classical tetrahedral cysteine/histidine binding sites to more complex binuclear sites with carboxylated lysine residues. According to the results, coordination spheres of hundreds of crystal structures in the PDB could be misinterpreted due to symmetry-related molecules or missing electron densities for ligands. The analysis also revealed increasing average metal-to-ligand bond length as a function of crystallographic resolution, which should be taken into account when interrogating metal ion binding sites. Moreover, one-third of the zinc ions present in crystal structures are artifacts, merely aiding crystal formation and packing with no biological significance. Our analysis provides solid evidence that a minimal stable zinc coordination sphere is made up by four ligands and adopts a tetrahedral coordination geometry.

  13. GADRAS Detector Response Function.

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, Dean J.; Harding, Lee; Thoreson, Gregory G; Horne, Steven M.

    2014-11-01

    The Gamma Detector Response and Analysis Software (GADRAS) applies a Detector Response Function (DRF) to compute the output of gamma-ray and neutron detectors when they are exposed to radiation sources. The DRF is fundamental to the ability to perform forward calculations (i.e., computation of the response of a detector to a known source), as well as the ability to analyze spectra to deduce the types and quantities of radioactive material to which the detectors are exposed. This document describes how gamma-ray spectra are computed and the significance of response function parameters that define characteristics of particular detectors.

  14. The TALE Tower Detector

    Science.gov (United States)

    Bergman, D. R.

    The TA Low Energy Extension will include a Tower FluorescenceDetector. Extensive air showers at the lowest usful energies for fluorescence detectors will in general be close to the detector. This requires viewing all elevation angles to be able to reconstruct showers. The TALE Tower Detector, operating in conjunction with other TALE detectors will view elevation angles up to above 70 degrees, with an azimuthal coverage of about 90 degrees. Results from a prototype mirror operated in conjunction with the HiRes detector will also be presented.

  15. The Finite Deformation Dynamic Sphere Test Problem

    Energy Technology Data Exchange (ETDEWEB)

    Versino, Daniele [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Brock, Jerry Steven [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-02

    In this manuscript we describe test cases for the dynamic sphere problem in presence of finite deformations. The spherical shell in exam is made of a homogeneous, isotropic or transverse isotropic material and elastic and elastic-plastic material behaviors are considered. Twenty cases, (a) to (t), are thus defined combining material types and boundary conditions. The inner surface radius, the outer surface radius and the material's density are kept constant for all the considered test cases and their values are ri = 10mm, ro = 20mm and p = 1000Kg/m3 respectively.

  16. Sphere impact and penetration into wet sand

    KAUST Repository

    Marston, J. O.

    2012-08-07

    We present experimental results for the penetration of a solid sphere when released onto wet sand. We show, by measuring the final penetration depth, that the cohesion induced by the water can result in either a deeper or shallower penetration for a given release height compared to dry granular material. Thus the presence of water can either lubricate or stiffen the granular material. By assuming the shear rate is proportional to the impact velocity and using the depth-averaged stopping force in calculating the shear stress, we derive effective viscosities for the wet granular materials.

  17. Sphere impact and penetration into wet sand

    Science.gov (United States)

    Marston, J. O.; Vakarelski, I. U.; Thoroddsen, S. T.

    2012-08-01

    We present experimental results for the penetration of a solid sphere when released onto wet sand. We show, by measuring the final penetration depth, that the cohesion induced by the water can result in either a deeper or shallower penetration for a given release height compared to dry granular material. Thus the presence of water can either lubricate or stiffen the granular material. By assuming the shear rate is proportional to the impact velocity and using the depth-averaged stopping force in calculating the shear stress, we derive effective viscosities for the wet granular materials.

  18. Locating a circle on a sphere

    DEFF Research Database (Denmark)

    Brimberg, Jack; Juel, Henrik; Schöbel, Anita

    2007-01-01

    We consider the problem of locating a spherical circle with respect to existing facilities on a sphere, such that the sum of distances between the circle and the facilities is minimized or such that the maximum distance is minimized. The problem properties are analyzed, and we give solution...... procedures. When the circle to be located is restricted to be a great circle, some simplifications are possible. The models may be used in preliminary studies on the location of large linear facilities on the earth's surface, such as superhighways, pipelines, and transmission lines, or in totally different...

  19. A pattern formation problem on the sphere

    Directory of Open Access Journals (Sweden)

    Clara E. Garza-Hume

    2007-02-01

    Full Text Available We consider a semi-linear elliptic equation on the sphere $mathbf{S}^n subset mathbb{R}^{n+1}$ with $n$ odd and subcritical nonlinearity. We show that given any positive integer $k$, if the exponent $p$ of the nonlinear term is sufficiently close to the critical Sobolev exponent $p^*$, then there exists a positive solution with $k$ peaks. Moreover, the minimum energy solutions with $k$ peaks are such that the centers of these concentrations converge as $po p^*$ to the solution of an underlying geometrical problem, namely, arranging $k$ points on $mathbf{S}^n$ so they are as far away from each other as possible.

  20. Nonlinear sequential laminates reproducing hollow sphere assemblages

    Science.gov (United States)

    Idiart, Martín I.

    2007-07-01

    A special class of nonlinear porous materials with isotropic 'sequentially laminated' microstructures is found to reproduce exactly the hydrostatic behavior of 'hollow sphere assemblages'. It is then argued that this result supports the conjecture that Gurson's approximate criterion for plastic porous materials, and its viscoplastic extension of Leblond et al. (1994), may actually yield rigorous upper bounds for the hydrostatic flow stress of porous materials containing an isotropic, but otherwise arbitrary, distribution of porosity. To cite this article: M.I. Idiart, C. R. Mecanique 335 (2007).

  1. NATURAL FREQUENCIES OF SUBMERGED PIEZOCERAMIC HOLLOW SPHERES

    Institute of Scientific and Technical Information of China (English)

    Cai Jinbiao; Chen Weiqiu; Ye Guiru; Ding Haojiang

    2000-01-01

    An exact 3D analysis of free vibration of a piezoceramic hollow sphere submerged in a compressible fluid is presented in this paper.A separation method is adopted to simplify the basic equations for spherically isotropic piezoelasticity.It is shown that there are two independent classes of vibration.The first one is independent of the fluid medium as well as the electric field,while the second is associated with both the fluid parameter and the piezoelectric effect.Exact frequency equations are derived and numerical results are obtained.

  2. Drift Chambers detectors; Detectores de deriva

    Energy Technology Data Exchange (ETDEWEB)

    Duran, I.; Martinez laso, L.

    1989-07-01

    We present here a review of High Energy Physics detectors based on drift chambers. The ionization, drift diffusion, multiplication and detection principles are described. Most common drift media are analysed, and a classification of the detectors according to its geometry is done. Finally the standard read-out methods are displayed and the limits of the spatial resolution are discussed. (Author) 115 refs.

  3. Multidensity integral-equation theory for short diblock hard-sphere-sticky-hard-sphere chains.

    Science.gov (United States)

    Wu, Ning; Chiew, Y C

    2010-04-01

    The multidensity Ornstein-Zernike integral equation theory is applied to study a simple model of hard sphere/sticky hard sphere diblock chains. The multidensity integral equation formalism has been successfully used to model the equilibrium structure and thermodynamic properties of homonuclear chains and shorter dimer fluids; to our knowledge it has not been applied to model diblock chains. In this work, a diblock chain fluids is represented by an m-component equal molar mixture of hard spheres with species 1,2,...,mh and sticky hard spheres with species mh+1,mh+2,...,m. Each spherical particle has two attractive sites A and B except species 1 and m, which have only one site per particle. In the limit of complete association, this mixture yields a system of monodisperse diblock chains. A general solution of this model is obtained in the Percus-Yevick, Polymer Percus-Yevick and ideal chain approximations. Both structural and thermodynamic properties of this model are investigated. From this study, a microphase separation is predicted for relatively short diblock symmetric and asymmetric chains. This microphase separation is enhanced at lower temperature and higher density. When chain length increases, the phase transition changes from a microphase level to a macrophase level. The size of microdomain structure is found to be dependent on total chain length, relative ratio of block lengths, temperature, and density.

  4. Percolation of disordered jammed sphere packings

    Science.gov (United States)

    Ziff, Robert M.; Torquato, Salvatore

    2017-02-01

    We determine the site and bond percolation thresholds for a system of disordered jammed sphere packings in the maximally random jammed state, generated by the Torquato–Jiao algorithm. For the site threshold, which gives the fraction of conducting versus non-conducting spheres necessary for percolation, we find {{p}\\text{c}}=0.3116(3) , consistent with the 1979 value of Powell 0.310(5) and identical within errors to the threshold for the simple-cubic lattice, 0.311 608, which shares the same average coordination number of 6. In terms of the volume fraction ϕ, the threshold corresponds to a critical value {φ\\text{c}}=0.199 . For the bond threshold, which apparently was not measured before, we find {{p}\\text{c}}=0.2424(3) . To find these thresholds, we considered two shape-dependent universal ratios involving the size of the largest cluster, fluctuations in that size, and the second moment of the size distribution; we confirmed the ratios’ universality by also studying the simple-cubic lattice with a similar cubic boundary. The results are applicable to many problems including conductivity in random mixtures, glass formation, and drug loading in pharmaceutical tablets.

  5. Characterizing HR3549B using SPHERE

    CERN Document Server

    Mesa, D; D'Orazi, V; Ginski, C; Desidera, S; Bonnefoy, M; Gratton, R; Langlois, M; Marzari, F; Messina, S; Antichi, J; Biller, B; Bonavita, M; Cascone, E; Chauvin, G; Claudi, R U; Curtis, I; Fantinel, D; Feldt, M; Garufi, A; Galicher, R; Henning, Th; Incorvaia, S; Lagrange, A M; Millward, M; Perrot, C; Salasnich, B; Scuderi, S; Sissa, E; Wahhaj, Z; Zurlo, A

    2016-01-01

    Aims. In this work, we characterize the low mass companion of the A0 field star HR3549. Methods. We observed HR3549AB in imaging mode with the the NIR branch (IFS and IRDIS) of SPHERE@VLT, with IFS in YJ mode and IRDIS in the H band. We also acquired a medium resolution spectrum with the IRDIS long slit spectroscopy mode. The data were reduced using the dedicated SPHERE GTO pipeline, purposely designed for this instrument. We employed algorithms such as PCA and TLOCI to reduce the speckle noise. Results. The companion was clearly visible both with IRDIS and IFS.We obtained photometry in four different bands as well as the astrometric position for the companion. Based on our astrometry, we confirm that it is a bound object and put constraints on its orbit. Although several uncertainties are still present, we estimate an age of ~100-150 Myr for this system, yielding a most probable mass for the companion of 40-50MJup and T_eff ~300-2400 K. Comparing with template spectra points to a spectral type between M9 and...

  6. Global warming in the public sphere.

    Science.gov (United States)

    Corfee-Morlot, Jan; Maslin, Mark; Burgess, Jacquelin

    2007-11-15

    Although the science of global warming has been in place for several decades if not more, only in the last decade and a half has the issue moved clearly into the public sphere as a public policy issue and a political priority. To understand how and why this has occurred, it is essential to consider the history of the scientific theory of the greenhouse effect, the evidence that supports it and the mechanisms through which science interacts with lay publics and other elite actors, such as politicians, policymakers and business decision makers. This article reviews why and how climate change has moved from the bottom to the top of the international political agenda. It traces the scientific discovery of global warming, political and institutional developments to manage it as well as other socially mediated pathways for understanding and promoting global warming as an issue in the public sphere. The article also places this historical overview of global warming as a public issue into a conceptual framework for understanding relationships between society and nature with emphasis on the co-construction of knowledge.

  7. Resonance for loop homology of spheres

    CERN Document Server

    Hingston, Nancy

    2011-01-01

    A Riemannian or Finsler metric on a compact manifold M gives rise to a length function on the free loop space \\Lambda M, whose critical points are the closed geodesics in the given metric. If X is a homology class on \\Lambda M, the minimax critical level cr(X) is a critical value. Let M be a sphere of dimension >2, and fix a metric g and a coefficient field G. We prove that the limit as deg(X) goes to infinity of cr(X)/deg(X) exists. We call this limit the "global mean frequency" of M. As a consequence we derive resonance statements for closed geodesics on spheres; in particular either all homology on \\Lambda M of sufficiently high degreee lies hanging on closed geodesics whose mean frequency (average index / length) equals the global mean frequency, or there is a sequence of infinitely many closed geodesics whose mean frequencies converge to the global mean frequency. The proof uses the Chas-Sullivan product and results of Goresky-Hingston [GH].

  8. Thermal kinetic inductance detector

    Energy Technology Data Exchange (ETDEWEB)

    Cecil, Thomas; Gades, Lisa; Miceli, Antonio; Quaranta, Orlando

    2016-12-20

    A microcalorimeter for radiation detection that uses superconducting kinetic inductance resonators as the thermometers. The detector is frequency-multiplexed which enables detector systems with a large number of pixels.

  9. Forward tracking detectors

    Indian Academy of Sciences (India)

    Klaus Mönig

    2007-11-01

    Forward tracking is an essential part of a detector at the international linear collider (ILC). The requirements for forward tracking are explained and the proposed solutions in the detector concepts are shown.

  10. Approximating and learning by Lipschitz kernel on the sphere

    Institute of Scientific and Technical Information of China (English)

    CAO Fei-long; WANG Chang-miao

    2014-01-01

    This paper investigates some approximation properties and learning rates of Lips-chitz kernel on the sphere. A perfect convergence rate on the shifts of Lipschitz kernel on the sphere, which is faster than O(n-1/2), is obtained, where n is the number of parameters needed in the approximation. By means of the approximation, a learning rate of regularized least square algorithm with the Lipschitz kernel on the sphere is also deduced.

  11. Lightcone dualities for curves in the lightcone unit 3-sphere

    OpenAIRE

    2013-01-01

    In this paper, we consider the curves in the unit 3-sphere in the lightcone. The unit 3-sphere can be canonically embedded in the lightcone and de Sitter 4-space in Lorentz-Minkowski 5-space. We investigate these curves in the framework of the theory of Legendrian dualities between pseudo-spheres in Lorentz-Minkowski 5-space. (C) 2013 AIP Publishing LLC.

  12. The CAPRICE RICH detector

    Energy Technology Data Exchange (ETDEWEB)

    Basini, G. [INFN, Laboratori Nazionali di Frascati, Rome (Italy); Codino, A.; Grimani, C. [Perugia Univ. (Italy)]|[INFN, Perugia (Italy); De Pascale, M.P. [Rome Univ. `Tor Vergata` (Italy). Dip. di Fisica]|[INFN, Sezione Univ. `Tor Vergata` Rome (Italy); Cafagna, F. [Bari Univ. (Italy)]|[INFN, Bari (Italy); Golden, R.L. [New Mexico State Univ., Las Cruces, NM (United States). Particle Astrophysics Lab.; Brancaccio, F.; Bocciolini, M. [Florence Univ. (Italy)]|[INFN, Florence (Italy); Barbiellini, G.; Boezio, M. [Trieste Univ. (Italy)]|[INFN, Trieste (Italy)

    1995-09-01

    A compact RICH detector has been developed and used for particle identification in a balloon borne spectrometer to measure the flux of antimatter in the cosmic radiation. This is the first RICH detector ever used in space experiments that is capable of detecting unit charged particles, such as antiprotons. The RICH and all other detectors performed well during the 27 hours long flight.

  13. GRADIENT INDEX SPHERES BY THE SEQUENTIAL ACCRETION OF GLASS POWDERS

    Energy Technology Data Exchange (ETDEWEB)

    MARIANO VELEZ

    2008-06-15

    The Department of Energy is seeking a method for fabricating mm-scale spheres having a refractive index that varies smoothly and continuously from the center to its surface [1]. The fabrication procedure must allow the creation of a range of index profiles. The spheres are to be optically transparent and have a refractive index differential greater than 0.2. The sphere materials can be either organic or inorganic and the fabrication technique must be capable of scaling to low cost production. Mo-Sci Corporation proposed to develop optical quality gradient refractive index (GRIN) glass spheres of millimeter scale (1 to 2 mm diameter) by the sequential accretion and consolidation of glass powders. Other techniques were also tested to make GRIN spheres as the powder-accretion method produced non-concentric layers and poor optical quality glass spheres. Potential ways to make the GRIN spheres were (1) by "coating" glass spheres (1 to 2 mm diameter) with molten glass in a two step process; and (2) by coating glass spheres with polymer layers.

  14. On $k$-stellated and $k$-stacked spheres

    OpenAIRE

    Bagchi, Bhaskar; Datta, Basudeb

    2012-01-01

    We introduce the class $\\Sigma_k(d)$ of $k$-stellated (combinatorial) spheres of dimension $d$ ($0 \\leq k \\leq d + 1$) and compare and contrast it with the class ${\\cal S}_k(d)$ ($0 \\leq k \\leq d$) of $k$-stacked homology $d$-spheres. We have $\\Sigma_1(d) = {\\cal S}_1(d)$, and $\\Sigma_k(d) \\subseteq {\\cal S}_k(d)$ for $d \\geq 2k - 1$. However, for each $k \\geq 2$ there are $k$-stacked spheres which are not $k$-stellated. The existence of $k$-stellated spheres which are not $k$-stacked remains...

  15. Oil capture from a water surface by a falling sphere

    Science.gov (United States)

    Smolka, Linda; McLaughlin, Clare; Witelski, Thomas

    2015-11-01

    When a spherical particle is dropped from rest into an oil lens that floats on top of a water surface, a portion of the oil adheres to the sphere. Once the sphere comes to rest at the subsurface, the oil forms a pendant drop that remains attached in equilibrium to the sphere effectively removing oil from the water surface. Best fit solutions of the Laplace equation to experimental profiles are used to investigate the parameter dependence of the radius of curvature and the filling and contact angles at the three-phase contact line of the pendant drop for spheres with different wetting properties, densities and radii. The volume of oil captured by a sphere increases with a sphere's mass and diameter. However, lighter and smaller spheres capture more oil relative to their own volume than do heavier and larger spheres (scaling with the sphere mass ~M - 0 . 544) and are thus more efficient at removing oil from a water surface. The authors wish to acknowledge the support of the National Science Foundation Grant Nos. DMS-0707755 and DMS-0968252.

  16. Bifundamental Fuzzy 2-Sphere and Fuzzy Killing Spinors

    Directory of Open Access Journals (Sweden)

    Horatiu Nastase

    2010-07-01

    Full Text Available We review our construction of a bifundamental version of the fuzzy 2-sphere and its relation to fuzzy Killing spinors, first obtained in the context of the ABJM membrane model. This is shown to be completely equivalent to the usual (adjoint fuzzy sphere. We discuss the mathematical details of the bifundamental fuzzy sphere and its field theory expansion in a model-independent way. We also examine how this new formulation affects the twisting of the fields, when comparing the field theory on the fuzzy sphere background with the compactification of the 'deconstructed' (higher dimensional field theory.

  17. IBM WebSphere Application Server 80 Administration Guide

    CERN Document Server

    Robinson, Steve

    2011-01-01

    IBM WebSphere Application Server 8.0 Administration Guide is a highly practical, example-driven tutorial. You will be introduced to WebSphere Application Server 8.0, and guided through configuration, deployment, and tuning for optimum performance. If you are an administrator who wants to get up and running with IBM WebSphere Application Server 8.0, then this book is not to be missed. Experience with WebSphere and Java would be an advantage, but is not essential.

  18. Extensive nuclear sphere generation in the human Alzheimer's brain.

    Science.gov (United States)

    Kolbe, Katharina; Bukhari, Hassan; Loosse, Christina; Leonhardt, Gregor; Glotzbach, Annika; Pawlas, Magdalena; Hess, Katharina; Theiss, Carsten; Müller, Thorsten

    2016-12-01

    Nuclear spheres are protein aggregates consisting of FE65, TIP60, BLM, and other yet unknown proteins. Generation of these structures in the cellular nucleus is putatively modulated by the amyloid precursor protein (APP), either by its cleavage or its phosphorylation. Nuclear spheres were preferentially studied in cell culture models and their existence in the human brain had not been known. Existence of nuclear spheres in the human brain was studied using immunohistochemistry. Cell culture experiments were used to study regulative mechanisms of nuclear sphere generation. The comparison of human frontal cortex brain samples from Alzheimer's disease (AD) patients to age-matched controls revealed a dramatically and highly significant enrichment of nuclear spheres in the AD brain. Costaining demonstrated that neurons are distinctly affected by nuclear spheres, but astrocytes never are. Nuclear spheres were predominantly found in neurons that were negative for threonine 668 residue in APP phosphorylation. Cell culture experiments revealed that JNK3-mediated APP phosphorylation reduces the amount of sphere-positive cells. The study suggests that nuclear spheres are a new APP-derived central hallmark of AD, which might be of crucial relevance for the molecular mechanisms in neurodegeneration.

  19. Hard-sphere limit of soft-sphere model for granular materials: Stiffness dependence of steady granular flow

    OpenAIRE

    Mitarai, Namiko; Nakanishi, Hiizu

    2002-01-01

    Dynamical behavior of steady granular flow is investigated numerically in the inelastic hard sphere limit of the soft sphere model. We find distinctively different limiting behaviors for the two flow regimes, i.e., the collisional flow and the frictional flow. In the collisional flow, the hard sphere limit is straightforward; the number of collisions per particle per unit time converges to a finite value and the total contact time fraction with other particles goes to zero. For the frictional...

  20. Simulation of flow and sediment mobility using a multidimensional flow model for the White Sturgeon critical-habitat reach, Kootenai River near Bonners Ferry, Idaho

    Science.gov (United States)

    Barton, Gary J.; McDonald, Richard R.; Nelson, Jonathan M.; Dinehart, Randal L.

    2005-01-01

    In 1994, the Kootenai River white sturgeon (Acipenser transmontanus) was listed as an Endangered Species as a direct result of two related observations. First, biologists observed that the white sturgeon population in the Kootenai River was declining. Second, they observed a decline in recruitment of juvenile sturgeon beginning in the 1950s with an almost total absence of recruitment since 1974, following the closure of Libby Dam in 1972. This second observation was attributed to changes in spawning and (or) rearing habitat resulting from alterations in the physical habitat, including flow regime, sediment-transport regime, and bed morphology of the river. The Kootenai River White Sturgeon Recovery Team was established to find and implement ways to improve spawning and rearing habitat used by white sturgeon. They identified the need to develop and apply a multidimensional flow model to certain reaches of the river to quantify physical habitat in a spatially distributed manner. The U.S. Geological Survey has addressed these needs by developing, calibrating, and validating a multidimensional flow model used to simulate streamflow and sediment mobility in the white sturgeon critical-habitat reach of the Kootenai River. This report describes the model and limitations, presents the results of a few simple simulations, and demonstrates how the model can be used to link physical characteristics of streamflow to biological or other habitat data. This study was conducted in cooperation with the Kootenai Tribe of Idaho along a 23-kilometer reach of the Kootenai River, including the white sturgeon spawning reach near Bonners Ferry, Idaho that is about 108 to 131 kilometers below Libby Dam. U.S. Geological Survey's MultiDimensional Surface-Water Modeling System was used to construct a flow model for the critical-habitat reach of the Kootenai River white sturgeon, between river kilometers 228.4 and 245.9. Given streamflow, bed roughness, and downstream water-surface elevation

  1. Inner Sphere and Outer Sphere Electron Transfer to Methyl Iodide. Deuterium and 13C Kinetic Isotope Effects

    DEFF Research Database (Denmark)

    Holm, Torkil; Crossland, Ingolf

    1996-01-01

    Deuterium and 13C kinetic isotope effects (KIEs) have been determined for the conversion of methyl iodide into methyl radical via inner sphere ET (electron transfer) and via outer sphere ET. The alfa-deuterium KIE was found to be very high for in......Deuterium and 13C kinetic isotope effects (KIEs) have been determined for the conversion of methyl iodide into methyl radical via inner sphere ET (electron transfer) and via outer sphere ET. The alfa-deuterium KIE was found to be very high for in...

  2. Quantum Baker map on the sphere

    CERN Document Server

    Pakonski, P; Zyczkowski, K; Pakonski, Prot; Ostruszka, Andrzej; Zyczkowski, Karol

    1998-01-01

    We construct analogue of the baker map on the sphere. We analyze its classical and quantum versions. The classical map is characterized by dynamical entropy equal to ln(2) and has a similar set of periodic orbits as the map on the torus. The quantum map is represented by a real, orthogonal matrix of an even dimension. Semiclassical dynamics and time evolution may be studied with the help of the SU(2) coherent states and the generalized Husimi distribution. In contrast to the standard baker map on the torus, the map analyzed in this paper does not exhibit the time reversal symmetry. Semiclassical ensemble of quantum maps, obtained by averaging over a range of matrix sizes, displays statistical properties characteristic of circular unitary ensemble.

  3. On the Torus Cobordant Cohomology Spheres

    Indian Academy of Sciences (India)

    Ali Özkurt; Doğan Dönmez

    2009-02-01

    Let be a compact Lie group. In 1960, P A Smith asked the following question: ``Is it true that for any smooth action of on a homotopy sphere with exactly two fixed points, the tangent -modules at these two points are isomorphic?" A result due to Atiyah and Bott proves that the answer is `yes’ for $\\mathbb{Z}_p$ and it is also known to be the same for connected Lie groups. In this work, we prove that two linear torus actions on $S^n$ which are -cobordant (cobordism in which inclusion of each boundary component induces isomorphisms in $\\mathbb{Z}$-cohomology) must be linearly equivalent. As a corollary, for connected case, we prove a variant of Smith’s question.

  4. High-energy detector

    Science.gov (United States)

    Bolotnikov, Aleksey E [South Setauket, NY; Camarda, Giuseppe [Farmingville, NY; Cui, Yonggang [Upton, NY; James, Ralph B [Ridge, NY

    2011-11-22

    The preferred embodiments are directed to a high-energy detector that is electrically shielded using an anode, a cathode, and a conducting shield to substantially reduce or eliminate electrically unshielded area. The anode and the cathode are disposed at opposite ends of the detector and the conducting shield substantially surrounds at least a portion of the longitudinal surface of the detector. The conducting shield extends longitudinally to the anode end of the detector and substantially surrounds at least a portion of the detector. Signals read from one or more of the anode, cathode, and conducting shield can be used to determine the number of electrons that are liberated as a result of high-energy particles impinge on the detector. A correction technique can be implemented to correct for liberated electron that become trapped to improve the energy resolution of the high-energy detectors disclosed herein.

  5. Equalized near maximum likelihood detector

    OpenAIRE

    2012-01-01

    This paper presents new detector that is used to mitigate intersymbol interference introduced by bandlimited channels. This detector is named equalized near maximum likelihood detector which combines nonlinear equalizer and near maximum likelihood detector. Simulation results show that the performance of equalized near maximum likelihood detector is better than the performance of nonlinear equalizer but worse than near maximum likelihood detector.

  6. Supercapacitor Performance of Hollow Carbon Spheres by Direct Pyrolysis of Melamine-formaldehyde Resin Spheres

    Institute of Scientific and Technical Information of China (English)

    MA Fang-wei; SUN Li-ping; ZHAO Hui; LI Qiang; HUO Li-hua; XIA Tian; GAO Shan

    2013-01-01

    The nitrogen and oxygen co-doped hollow carbon spheres(HCSs) were prepared via a simple pyrolysis of solid melamine-formaldhyde resin spheres.The carbonization temperature has an important influence on the specific surface area,pore-size distribution and heteroatom contents of HCSs.The synergistic effects of those physical and chemical properties on supercapacitor performance were systematically investigated.Among the HCSs obtained at different temperatures,HCSs-800(co-doped HCSs at 800 ℃) exhibits the best reversible specific capacitance in 2 mol/L H2SO4 electrolyte and meanwhile maintains a high-class capacitance retention capability.The nitrogen heteroatoms were confirmed to play a crucial role in improving capacitance in an acid medium.This kind of nitrogen doped HCSs is a potential candidate for an efficient electrode material for supercapacitors.

  7. Weighted Approximation for Jackson-Matsuoka Polynomials on the Sphere

    Directory of Open Access Journals (Sweden)

    Guo Feng

    2012-01-01

    Full Text Available We consider the best approximation by Jackson-Matsuoka polynomials in the weighted Lp space on the unit sphere of Rd. Using the relation between K-functionals and modulus of smoothness on the sphere, we obtain the direct and inverse estimate of approximation by these polynomials for the h-spherical harmonics.

  8. VMware vSphere 5.5 cookbook

    CERN Document Server

    G B, Abhilash

    2015-01-01

    This is an excellent handbook for system administrators, support professionals, or for anyone intending to give themselves a headstart in learning how to install, configure, and manage a vSphere environment. It is also a good task-oriented reference guide for consultants or infrastructure architects who design and deploy vSphere environments.

  9. Squeeze flow between a sphere and a textured wall

    Energy Technology Data Exchange (ETDEWEB)

    Chastel, T.; Mongruel, A., E-mail: anne.mongruel@upmc.fr [Physique et Mécanique des Milieux Hétérogènes, UMR 7636 CNRS–ESPCI, Université Pierre et Marie Curie–Université Paris-Diderot, 10 rue Vauquelin, 75231 Paris Cedex 05 (France)

    2016-02-15

    The motion of a millimetric sphere, translating in a viscous fluid towards a wettable textured wall, is investigated experimentally. The textures consist of square arrays of cylindrical or square micro-pillars, the height, width, and spacing of which are varied, keeping the periodicity small compared to the sphere radius. An interferometric device is used to measure the sphere vertical displacement, for distances between the sphere and the base of the pillars smaller than 0.1 sphere radius, and with a resolution of 200 nm. At a given distance from the top of the pillars, the sphere velocity is found to be significantly larger than the corresponding velocity for a smooth solid wall. A squeeze flow model of two adjacent fluid layers is developed in the lubrication approximation, one fluid layer having an effective viscosity that reflects the viscous dissipation through the array of pillars. The pressure field in the gap between the sphere and the textured surface is then used to obtain the drag force on the sphere and hence its velocity. Adjustment of the model to the velocity measurements yields the effective viscosity for a given texture. Finally, a correlation between the effective viscosity and the geometry of the pillar array is proposed.

  10. Orbital Motion of Electrically Charged Spheres in Microgravity

    Science.gov (United States)

    Banerjee, Shubho; Andring, Kevin; Campbell, Desmond; Janeski, John; Keedy, Daniel; Quinn, Sean; Hoffmeister, Brent

    2008-01-01

    The similar mathematical forms of Coulomb's law and Newton's law of gravitation suggest that two uniformly charged spheres should be able to orbit each other just as two uniform spheres of mass are known to do. In this paper we describe an experiment that we performed to demonstrate such an orbit. This is the first published account of a…

  11. Homological properties of Podle′s quantum spheres

    Institute of Scientific and Technical Information of China (English)

    LIU LiYu; SHEN YunYi; WU QuanShui

    2014-01-01

    The standard Podle′s quantum sphere is Artin-Schelter regular as showed by Kra¨hmer(2012).The non-standard Podle′s quantum spheres are proved to be Auslander-regular,Cohen-Macaulay and Artin-Schelter regular in this paper.

  12. The sintering behavior of close-packed spheres

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Tikare, V.; Frandsen, Henrik Lund

    2012-01-01

    The sintering behavior of close-packed spheres is investigated using a numerical model. The investigated systems are the body-centered cubic (bcc), face-centered cubic (fcc) and hexagonal close-packed spheres (hcp). The sintering behavior is found to be ideal, with no grain growth until full dens...

  13. Axioms of spheres in lightlike geometry of submanifolds

    Indian Academy of Sciences (India)

    RACHNA RANI; RAKESH KUMAR; R K NAGAICH

    2016-10-01

    We prove that if an indefinite Kaehler manifold $\\bar{M}$ with lightlike submanifolds satisfies the axioms of holomorphic 2$r$-spheres, axioms of holomorphic 2$r$-planes, axioms of transversal $r$-spheres and axioms of transversal $r$-planes, then it is an indefinite complex space form.

  14. Creeping Viscous Flow around a Heat-Generating Solid Sphere

    DEFF Research Database (Denmark)

    Krenk, Steen

    1981-01-01

    The velocity field for creeping viscous flow around a solid sphere due to a spherically symmetric thermal field is determined and a simple thermal generalization of Stokes' formula is obtained. The velocity field due to an instantaneous heat source at the center of the sphere is obtained in close...... form and an application to the storage of heat-generating nuclear waste is discussed....

  15. A REMARK ON THE QUASI-HARMONIC SPHERES

    Institute of Scientific and Technical Information of China (English)

    XuDeliang; ZhouChunqin

    2002-01-01

    Several theorems on the finiteness of energy for quasi-harmonic spheres are proved,some counter-examples which state that the energy of quasi-harmonic sphere may be infinite are given. The results support some conditions of a question posed by Lin Fanghua and Wang Changyou.

  16. Dual-Purpose Millikan Experiment with Polystyrene Spheres

    Science.gov (United States)

    Wall, C. N.; Christensen, F. E.

    1975-01-01

    This procedure, using polystyrene spheres of specified diameter, renders the Millikan oil drop experiment more accurate than the conventional procedure of the polystyrene spheres, eliminates size estimation error, and removes the guesswork involved in assigning proper index integers to the observed charges. (MLH)

  17. Direct measurement of thermodynamic properties of colloidal hard spheres

    NARCIS (Netherlands)

    Dullens, R.P.A.; Kegel, W.K.; Aarts, D.G.A.L.

    2008-01-01

    Recently, we have shown how to measure thermodynamic properties of colloidal hard sphere suspensions by microscopy [Dullens et al. (2006) PNAS 103, 529]. Here, we give full experimental details on how to acquire three dimensional snapshots of a colloidal hard sphere suspension over a wide range of d

  18. Impact of supersymmetry on the nonperturbative dynamics of fuzzy spheres

    CERN Document Server

    Anagnostopoulos, K N; Nagao, K; Nishimura, J; Anagnostopoulos, Konstantinos N.; Azuma, Takehiro; Nagao, Keiichi; Nishimura, Jun

    2005-01-01

    We study a 4d supersymmetric matrix model with a cubic term, which incorporates fuzzy spheres as classical solutions, using Monte Carlo simulations and perturbative calculations. The fuzzy sphere in the supersymmetric model turns out to be always stable if the large-N limit is taken in such a way that various correlation functions scale. This is in striking contrast to analogous bosonic models, where the fuzzy sphere decays into the pure Yang-Mills vacuum due to quantum effects when the coefficient of the cubic term becomes smaller than a critical value. We also find that the power-law tail of the eigenvalue distribution, which exists in the supersymmetric model without the cubic term, disappears in the presence of the fuzzy sphere in the large-N limit. Coincident fuzzy spheres turn out to be unstable, which implies that the dynamically generated gauge group is U(1).

  19. On-Chip Fabrication of Glass Sphere Laser

    Directory of Open Access Journals (Sweden)

    Kishi Tetsuo

    2015-01-01

    Full Text Available Fabrication and application of glass spherical micro-cavity for lasing are reported. Surface-tension molding (StM and localized-laser heating (LLH techniques have been developed to fabricate glass super sphere, which is partially truncated spherical shape, and true spheres, respectively. Whispering gallery mode (WGM resonances or laser oscillations from the spherical glasses were demonstrated. Super-spherical glasses possessed WGM resonances on its equatorial plane. The equatorial plane with high roundness (>0.99 serves a high quality factor to lead laser oscillation. LLH technique enables us to fabricate true spheres on a transparent substrate. Tellurite glass spheres prepared by the LLH technique showed laser oscillation with few-mW-order thresholds by direct pumping. StM and LLH technique are very suitable for both preparation and utilization of glass spheres for optical micro-cavity.

  20. SPHERE: a scalable multicast framework in overlay networks

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper presents Sphere, a scalable multicast framework in overlay network. Sphere is a highly efficient, self-organizing and robust multicast protocol overlayed on the Internet. The main contributions of this paper are twofold. First, Sphere organizes the control topology of overlay network in two directions: horizontal and vertical. The horizontal meshes are used to locate and organize hosts in tracks, and the vertical meshes are used to manage the data paths between tracks. Second, Sphere balances stress and stretch of the overlay network by assigning hosts into different tracks and clusters. This structure distributes stress on the multicast trees uniformly, and meantime makes path stretch as small as possible.Simulations results show that Sphere can support multicast with large group size and has good performance on organizing meshes and building data delivery trees.

  1. Encapsulation of urease enzyme in xanthan-alginate spheres.

    Science.gov (United States)

    Elçin, Y M

    1995-10-01

    Urease-containing xanthan-alginate spheres were prepared by a two-step process which involved the Ca2+ coupling of the polysaccharides, followed by gentle glutaraldehyde cross-linking with amine groups of gelatin present in the initial mixture. This second step caused a slight decrease in the enzymatic activity but increased the stability. The water content and size distribution of the spheres were examined together with the sphere morphology. The effect of polymer ratio and enzyme loading on urease activity was investigated. An increase in xanthan content was found to affect the water uptake of the spheres. Temperature and pH stability of encapsulated urease was found to be higher than the free form. The xanthan-alginate spheres showed 75% of maximum urease activity even after 20 repeated uses under optimal conditions.

  2. Imaging spheres with general incident wavefronts using a dipole decomposition

    Science.gov (United States)

    Izen, Steven H.; Ovryn, Ben

    1998-06-01

    Although scattering for spheres with plane wave illumination was solved precisely by Mie in 1909, often it is of interest to image spheres with non-planar illumination. An extension of Mie theory which incorporates non-planar illumination requires knowledge of the coefficients for a spherical harmonic expansion of the incident wavefront about the center of the sphere. These coefficients have been determined for a few special cases, such as Gaussian beams, which have a relatively simple model. Using a vectorized Huygen's principle, a general vector wavefront can be represented as a superposition of dipole sources. We have computed the spherical wave function expansion coefficients of an arbitrarily placed dipole and hence the scattering from a sphere illuminated by a general wavefront can be computed. As a special case, Mie's solution of plane wave scattering was recovered. POtential applications include scattering with partially coherent illumination. Experimental results from the scattering from polystyrene spheres using Koehler illumination show agreement with numerical tests.

  3. Priority Guidelines Of The Service Sphere Development In Uzbekistan

    Directory of Open Access Journals (Sweden)

    Bakhtiyor Safarov

    2011-04-01

    Full Text Available The present research article is devoted to study the priorities of service sphere development in Uzbekistan. The comparative analysis of service sphere development during 1996-2009 were presented, survey of disperse territories, analysis and generalization methods used to identify trends in services sphere. Disperse markets were grouped into markets with high, medium and low development level.  Retail trade is identified one of the most important components of service sphere in Uzbekistan. Retail turnover figures were predicted until 2013 used retrospective data for forecasting. Linear trend - trends of increase or decrease of index, visual analysis of time series dynamics(graphic presentation were used to solve the studied problem. Main priorities and targets in service sphere in Uzbekistan and it’s role in economy were determined.

  4. Holomorphic Two-Spheres in Complex Grassmann Manifold (2, 4)

    Indian Academy of Sciences (India)

    Xiaowei Xu; Xiaoxiang Jiao

    2008-08-01

    In this paper, we use the harmonic sequence to study the linearly full holomorphic two-spheres in complex Grassmann manifold (2,4). We show that if the Gaussian curvature (with respect to the induced metric) of a non-degenerate holomorphic two-sphere satisfies ≤ 2 (or ≥ 2), then must be equal to 2. Simultaneously, we show that one class of the holomorphic two-spheres with constant curvature 2 is totally geodesic. Concerning the degenerate holomorphic two-spheres, if its Gaussian curvature ≤ 1 (or ≥ 1), then =1. Moreover, we prove that all holomorphic two-spheres with constant curvature 1 in (2,4) must be (4)-equivalent.

  5. Reconstruction of neutron spectra through neural networks; Reconstruccion de espectros de neutrones mediante redes neuronales

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H.R.; Hernandez D, V.M.; Manzanares A, E. [Cuerpo Academico de Radiobiologia, Estudios Nucleares, Universidad Autonoma de Zacatecas, A.P. 336, 98000 Zacatecas (Mexico)] e-mail: rvega@cantera.reduaz.mx [and others

    2003-07-01

    A neural network has been used to reconstruct the neutron spectra starting from the counting rates of the detectors of the Bonner sphere spectrophotometric system. A group of 56 neutron spectra was selected to calculate the counting rates that would produce in a Bonner sphere system, with these data and the spectra it was trained the neural network. To prove the performance of the net, 12 spectra were used, 6 were taken of the group used for the training, 3 were obtained of mathematical functions and those other 3 correspond to real spectra. When comparing the original spectra of those reconstructed by the net we find that our net has a poor performance when reconstructing monoenergetic spectra, this attributes it to those characteristic of the spectra used for the training of the neural network, however for the other groups of spectra the results of the net are appropriate with the prospective ones. (Author)

  6. Dynamic simulation of sphere motion in a vertical tube

    Science.gov (United States)

    Yu, Zhaosheng; Phan-Thien, Nhan; Tanner, Roger I.

    2004-11-01

    In this paper, the sedimentation of a sphere and its radial migration in a Poiseuille flow in a vertical tube filled with a Newtonian fluid are simulated with a finite-difference-based distributed Lagrange multiplier (DLM) method. The flow features, the settling velocities, the trajectories and the angular velocities of the spheres sedimenting in a tube at different Reynolds numbers are presented. The results show that at relatively low Reynolds numbers, the sphere approaches the tube axis monotonically, whereas in a high-Reynolds-number regime where shedding of vortices takes place, the sphere takes up a spiral trajectory that is closer to the tube wall than the tube axis. The rotation motion and the lateral motion of the sphere are highly correlated through the Magnus effect, which is verified to be an important (but not the only) driving force for the lateral migration of the sphere at relatively high Reynolds numbers. The standard vortex structures in the wake of a sphere, for Reynolds number higher than 400, are composed of a loop mainly located in a plane perpendicular to the streamwise direction and two streamwise vortex pairs. When moving downstream, the legs of the hairpin vortex retract and at the same time a streamwise vortex pair with rotation opposite to that of the legs forms between the loops. For Reynolds number around 400, the wake structures shed during the impact of the sphere on the wall typically form into streamwise vortex structures or else into hairpin vortices when the sphere spirals down. The radial, angular and axial velocities of both neutrally buoyant and non-neutrally buoyant spheres in a circular Poiseuille flow are reported. The results are in remarkably good agreement with the available experimental data. It is shown that suppresion of the sphere rotation produces significant large additional lift forces pointing towards the tube axis on the spheres in the neutrally buoyant and more-dense-downflow cases, whereas it has a negligible

  7. Noble Gas Detectors

    CERN Document Server

    Aprile, Elena; Bolozdynya, Alexander I; Doke, Tadayoshi

    2006-01-01

    This book discusses the physical properties of noble fluids, operational principles of detectors based on these media, and the best technical solutions to the design of these detectors. Essential attention is given to detector technology: purification methods and monitoring of purity, information readout methods, electronics, detection of hard ultra-violet light emission, selection of materials, cryogenics etc.The book is mostly addressed to physicists and graduate students involved in the preparation of fundamental next generation experiments, nuclear engineers developing instrumentation

  8. Physics of Hard Spheres Experiment: Significant and Quantitative Findings Made

    Science.gov (United States)

    Doherty, Michael P.

    2000-01-01

    Direct examination of atomic interactions is difficult. One powerful approach to visualizing atomic interactions is to study near-index-matched colloidal dispersions of microscopic plastic spheres, which can be probed by visible light. Such spheres interact through hydrodynamic and Brownian forces, but they feel no direct force before an infinite repulsion at contact. Through the microgravity flight of the Physics of Hard Spheres Experiment (PHaSE), researchers have sought a more complete understanding of the entropically driven disorder-order transition in hard-sphere colloidal dispersions. The experiment was conceived by Professors Paul M. Chaikin and William B. Russel of Princeton University. Microgravity was required because, on Earth, index-matched colloidal dispersions often cannot be density matched, resulting in significant settling over the crystallization period. This settling makes them a poor model of the equilibrium atomic system, where the effect of gravity is truly negligible. For this purpose, a customized light-scattering instrument was designed, built, and flown by the NASA Glenn Research Center at Lewis Field on the space shuttle (shuttle missions STS 83 and STS 94). This instrument performed both static and dynamic light scattering, with sample oscillation for determining rheological properties. Scattered light from a 532- nm laser was recorded either by a 10-bit charge-coupled discharge (CCD) camera from a concentric screen covering angles of 0 to 60 or by sensitive avalanche photodiode detectors, which convert the photons into binary data from which two correlators compute autocorrelation functions. The sample cell was driven by a direct-current servomotor to allow sinusoidal oscillation for the measurement of rheological properties. Significant microgravity research findings include the observation of beautiful dendritic crystals, the crystallization of a "glassy phase" sample in microgravity that did not crystallize for over 1 year in 1g

  9. ALFA Detector Control System

    CERN Document Server

    Oleiro Seabra, Luis Filipe; The ATLAS collaboration

    2015-01-01

    ALFA (Absolute Luminosity For ATLAS) is one of the sub-detectors of ATLAS (A Toroidal LHC Apparatus). The ALFA system is composed by four stations installed in the LHC tunnel 240 m away from the ATLAS interaction point. Each station has a vacuum and ventilation system, movement control and all the required electronics for signal processing. The Detector Control System (DCS) provides control and monitoring of several components and ensures the safe operation of the detector contributing to good Data Quality. This paper describes the ALFA DCS system including a detector overview, operation aspects and hardware control through a SCADA system, WinCC OA.

  10. LHCb Detector Performance

    CERN Document Server

    AUTHOR|(CDS)2075808; Adeva, Bernardo; Adinolfi, Marco; Affolder, Anthony; Ajaltouni, Ziad; Akar, Simon; Albrecht, Johannes; Alessio, Federico; Alexander, Michael; Ali, Suvayu; Alkhazov, Georgy; Alvarez Cartelle, Paula; Alves Jr, Antonio Augusto; Amato, Sandra; Amerio, Silvia; Amhis, Yasmine; An, Liupan; Anderlini, Lucio; Anderson, Jonathan; Andreassen, Rolf; Andreotti, Mirco; Andrews, Jason; Appleby, Robert; Aquines Gutierrez, Osvaldo; Archilli, Flavio; Artamonov, Alexander; Artuso, Marina; Aslanides, Elie; Auriemma, Giulio; Baalouch, Marouen; Bachmann, Sebastian; Back, John; Badalov, Alexey; Baesso, Clarissa; Baldini, Wander; Barlow, Roger; Barschel, Colin; Barsuk, Sergey; Barter, William; Batozskaya, Varvara; Battista, Vincenzo; Bay, Aurelio; Beaucourt, Leo; Beddow, John; Bedeschi, Franco; Bediaga, Ignacio; Belogurov, Sergey; Belous, Konstantin; Belyaev, Ivan; Ben-Haim, Eli; Bencivenni, Giovanni; Benson, Sean; Benton, Jack; Berezhnoy, Alexander; Bernet, Roland; Bettler, Marc-Olivier; van Beuzekom, Martinus; Bien, Alexander; Bifani, Simone; Bird, Thomas; Bizzeti, Andrea; Bjørnstad, Pål Marius; Blake, Thomas; Blanc, Frédéric; Blouw, Johan; Blusk, Steven; Bocci, Valerio; Bondar, Alexander; Bondar, Nikolay; Bonivento, Walter; Borghi, Silvia; Borgia, Alessandra; Borsato, Martino; Bowcock, Themistocles; Bowen, Espen Eie; Bozzi, Concezio; Brambach, Tobias; Bressieux, Joël; Brett, David; Britsch, Markward; Britton, Thomas; Brodzicka, Jolanta; Brook, Nicholas; Brown, Henry; Bursche, Albert; Buytaert, Jan; Cadeddu, Sandro; Calabrese, Roberto; Calvi, Marta; Calvo Gomez, Miriam; Campana, Pierluigi; Campora Perez, Daniel; Carbone, Angelo; Carboni, Giovanni; Cardinale, Roberta; Cardini, Alessandro; Carson, Laurence; Carvalho Akiba, Kazuyoshi; Casse, Gianluigi; Cassina, Lorenzo; Castillo Garcia, Lucia; Cattaneo, Marco; Cauet, Christophe; Cenci, Riccardo; Charles, Matthew; Charpentier, Philippe; Chefdeville, Maximilien; Chen, Shanzhen; Cheung, Shu-Faye; Chiapolini, Nicola; Chrzaszcz, Marcin; Ciba, Krzystof; Cid Vidal, Xabier; Ciezarek, Gregory; Clarke, Peter; Clemencic, Marco; Cliff, Harry; Closier, Joel; Coco, Victor; Cogan, Julien; Cogneras, Eric; Cogoni, Violetta; Cojocariu, Lucian; Collazuol, Gianmaria; Collins, Paula; Comerma-Montells, Albert; Contu, Andrea; Cook, Andrew; Coombes, Matthew; Coquereau, Samuel; Corti, Gloria; Corvo, Marco; Counts, Ian; Couturier, Benjamin; Cowan, Greig; Craik, Daniel Charles; Crocombe, Andrew; Cruz Torres, Melissa Maria; Cunliffe, Samuel; Currie, Robert; D'Ambrosio, Carmelo; Dalseno, Jeremy; David, Pascal; David, Pieter; Davis, Adam; De Bruyn, Kristof; De Capua, Stefano; De Cian, Michel; De Miranda, Jussara; De Paula, Leandro; De Silva, Weeraddana; De Simone, Patrizia; Decamp, Daniel; Deckenhoff, Mirko; Del Buono, Luigi; Déléage, Nicolas; Derkach, Denis; Deschamps, Olivier; Dettori, Francesco; Di Canto, Angelo; Dijkstra, Hans; Donleavy, Stephanie; Dordei, Francesca; Dorigo, Mirco; Dosil Suárez, Alvaro; Dossett, David; Dovbnya, Anatoliy; Dreimanis, Karlis; Dujany, Giulio; Dupertuis, Frederic; Durante, Paolo; Dzhelyadin, Rustem; Dziurda, Agnieszka; Dzyuba, Alexey; Easo, Sajan; Egede, Ulrik; Egorychev, Victor; Eidelman, Semen; Eisenhardt, Stephan; Eitschberger, Ulrich; Ekelhof, Robert; Eklund, Lars; El Rifai, Ibrahim; Elsasser, Christian; Ely, Scott; Esen, Sevda; Evans, Hannah Mary; Evans, Timothy; Falabella, Antonio; Färber, Christian; Farinelli, Chiara; Farley, Nathanael; Farry, Stephen; Fay, Robert; Ferguson, Dianne; Fernandez Albor, Victor; Ferreira Rodrigues, Fernando; Ferro-Luzzi, Massimiliano; Filippov, Sergey; Fiore, Marco; Fiorini, Massimiliano; Firlej, Miroslaw; Fitzpatrick, Conor; Fiutowski, Tomasz; Fol, Philip; Fontana, Marianna; Fontanelli, Flavio; Forty, Roger; Francisco, Oscar; Frank, Markus; Frei, Christoph; Frosini, Maddalena; Fu, Jinlin; Furfaro, Emiliano; Gallas Torreira, Abraham; Galli, Domenico; Gallorini, Stefano; Gambetta, Silvia; Gandelman, Miriam; Gandini, Paolo; Gao, Yuanning; García Pardiñas, Julián; Garofoli, Justin; Garra Tico, Jordi; Garrido, Lluis; Gascon, David; Gaspar, Clara; Gauld, Rhorry; Gavardi, Laura; Geraci, Angelo; Gersabeck, Evelina; Gersabeck, Marco; Gershon, Timothy; Ghez, Philippe; Gianelle, Alessio; Gianì, Sebastiana; Gibson, Valerie; Giubega, Lavinia-Helena; Gligorov, Vladimir; Göbel, Carla; Golubkov, Dmitry; Golutvin, Andrey; Gomes, Alvaro; Gotti, Claudio; Grabalosa Gándara, Marc; Graciani Diaz, Ricardo; Granado Cardoso, Luis Alberto; Graugés, Eugeni; Graverini, Elena; Graziani, Giacomo; Grecu, Alexandru; Greening, Edward; Gregson, Sam; Griffith, Peter; Grillo, Lucia; Grünberg, Oliver; Gui, Bin; Gushchin, Evgeny; Guz, Yury; Gys, Thierry; Hadjivasiliou, Christos; Haefeli, Guido; Haen, Christophe; Haines, Susan; Hall, Samuel; Hamilton, Brian; Hampson, Thomas; Han, Xiaoxue; Hansmann-Menzemer, Stephanie; Harnew, Neville; Harnew, Samuel; Harrison, Jonathan; He, Jibo; Head, Timothy; Heijne, Veerle; Hennessy, Karol; Henrard, Pierre; Henry, Louis; Hernando Morata, Jose Angel; van Herwijnen, Eric; Heß, Miriam; Hicheur, Adlène; Hill, Donal; Hoballah, Mostafa; Hombach, Christoph; Hulsbergen, Wouter; Hunt, Philip; Hussain, Nazim; Hutchcroft, David; Hynds, Daniel; Idzik, Marek; Ilten, Philip; Jacobsson, Richard; Jaeger, Andreas; Jalocha, Pawel; Jans, Eddy; Jaton, Pierre; Jawahery, Abolhassan; Jing, Fanfan; John, Malcolm; Johnson, Daniel; Jones, Christopher; Joram, Christian; Jost, Beat; Jurik, Nathan; Kandybei, Sergii; Kanso, Walaa; Karacson, Matthias; Karbach, Moritz; Karodia, Sarah; Kelsey, Matthew; Kenyon, Ian; Ketel, Tjeerd; Khanji, Basem; Khurewathanakul, Chitsanu; Klaver, Suzanne; Klimaszewski, Konrad; Kochebina, Olga; Kolpin, Michael; Komarov, Ilya; Koopman, Rose; Koppenburg, Patrick; Korolev, Mikhail; Kozlinskiy, Alexandr; Kravchuk, Leonid; Kreplin, Katharina; Kreps, Michal; Krocker, Georg; Krokovny, Pavel; Kruse, Florian; Kucewicz, Wojciech; Kucharczyk, Marcin; Kudryavtsev, Vasily; Kurek, Krzysztof; Kvaratskheliya, Tengiz; La Thi, Viet Nga; Lacarrere, Daniel; Lafferty, George; Lai, Adriano; Lambert, Dean; Lambert, Robert W; Lanfranchi, Gaia; Langenbruch, Christoph; Langhans, Benedikt; Latham, Thomas; Lazzeroni, Cristina; Le Gac, Renaud; van Leerdam, Jeroen; Lees, Jean-Pierre; Lefèvre, Regis; Leflat, Alexander; Lefrançois, Jacques; Leo, Sabato; Leroy, Olivier; Lesiak, Tadeusz; Leverington, Blake; Li, Yiming; Likhomanenko, Tatiana; Liles, Myfanwy; Lindner, Rolf; Linn, Christian; Lionetto, Federica; Liu, Bo; Lohn, Stefan; Longstaff, Iain; Lopes, Jose; Lopez-March, Neus; Lowdon, Peter; Lucchesi, Donatella; Luo, Haofei; Lupato, Anna; Luppi, Eleonora; Lupton, Oliver; Machefert, Frederic; Machikhiliyan, Irina V; Maciuc, Florin; Maev, Oleg; Malde, Sneha; Malinin, Alexander; Manca, Giulia; Mancinelli, Giampiero; Mapelli, Alessandro; Maratas, Jan; Marchand, Jean François; Marconi, Umberto; Marin Benito, Carla; Marino, Pietro; Märki, Raphael; Marks, Jörg; Martellotti, Giuseppe; Martens, Aurelien; Martín Sánchez, Alexandra; Martinelli, Maurizio; Martinez Santos, Diego; Martinez Vidal, Fernando; Martins Tostes, Danielle; Massafferri, André; Matev, Rosen; Mathe, Zoltan; Matteuzzi, Clara; Mazurov, Alexander; McCann, Michael; McCarthy, James; McNab, Andrew; McNulty, Ronan; McSkelly, Ben; Meadows, Brian; Meier, Frank; Meissner, Marco; Merk, Marcel; Milanes, Diego Alejandro; Minard, Marie-Noelle; Moggi, Niccolò; Molina Rodriguez, Josue; Monteil, Stephane; Morandin, Mauro; Morawski, Piotr; Mordà, Alessandro; Morello, Michael Joseph; Moron, Jakub; Morris, Adam Benjamin; Mountain, Raymond; Muheim, Franz; Müller, Katharina; Mussini, Manuel; Muster, Bastien; Naik, Paras; Nakada, Tatsuya; Nandakumar, Raja; Nasteva, Irina; Needham, Matthew; Neri, Nicola; Neubert, Sebastian; Neufeld, Niko; Neuner, Max; Nguyen, Anh Duc; Nguyen, Thi-Dung; Nguyen-Mau, Chung; Nicol, Michelle; Niess, Valentin; Niet, Ramon; Nikitin, Nikolay; Nikodem, Thomas; Novoselov, Alexey; O'Hanlon, Daniel Patrick; Oblakowska-Mucha, Agnieszka; Obraztsov, Vladimir; Oggero, Serena; Ogilvy, Stephen; Okhrimenko, Oleksandr; Oldeman, Rudolf; Onderwater, Gerco; Orlandea, Marius; Otalora Goicochea, Juan Martin; Owen, Patrick; Oyanguren, Maria Arantza; Pal, Bilas Kanti; Palano, Antimo; Palombo, Fernando; Palutan, Matteo; Panman, Jacob; Papanestis, Antonios; Pappagallo, Marco; Pappalardo, Luciano; Parkes, Christopher; Parkinson, Christopher John; Passaleva, Giovanni; Patel, Girish; Patel, Mitesh; Patrignani, Claudia; Pearce, Alex; Pellegrino, Antonio; Penso, Gianni; Pepe Altarelli, Monica; Perazzini, Stefano; Perret, Pascal; Perrin-Terrin, Mathieu; Pescatore, Luca; Pesen, Erhan; Pessina, Gianluigi; Petridis, Konstantin; Petrolini, Alessandro; Picatoste Olloqui, Eduardo; Pietrzyk, Boleslaw; Pilař, Tomas; Pinci, Davide; Pistone, Alessandro; Playfer, Stephen; Plo Casasus, Maximo; Polci, Francesco; Poluektov, Anton; Polyakov, Ivan; Polycarpo, Erica; Popov, Alexander; Popov, Dmitry; Popovici, Bogdan; Potterat, Cédric; Price, Eugenia; Price, Joseph David; Prisciandaro, Jessica; Pritchard, Adrian; Prouve, Claire; Pugatch, Valery; Puig Navarro, Albert; Punzi, Giovanni; Qian, Wenbin; Rachwal, Bartolomiej; Rademacker, Jonas; Rakotomiaramanana, Barinjaka; Rama, Matteo; Rangel, Murilo; Raniuk, Iurii; Rauschmayr, Nathalie; Raven, Gerhard; Redi, Federico; Reichert, Stefanie; Reid, Matthew; dos Reis, Alberto; Ricciardi, Stefania; Richards, Sophie; Rihl, Mariana; Rinnert, Kurt; Rives Molina, Vincente; Robbe, Patrick; Rodrigues, Ana Barbara; Rodrigues, Eduardo; Rodriguez Perez, Pablo; Roiser, Stefan; Romanovsky, Vladimir; Romero Vidal, Antonio; Rotondo, Marcello; Rouvinet, Julien; Ruf, Thomas; Ruiz, Hugo; Ruiz Valls, Pablo; Saborido Silva, Juan Jose; Sagidova, Naylya; Sail, Paul; Saitta, Biagio; Salustino Guimaraes, Valdir; Sanchez Mayordomo, Carlos; Sanmartin Sedes, Brais; Santacesaria, Roberta; Santamarina Rios, Cibran; Santovetti, Emanuele; Sarti, Alessio; Satriano, Celestina; Satta, Alessia; Saunders, Daniel Martin; Savrina, Darya; Schiller, Manuel; Schindler, Heinrich; Schlupp, Maximilian; Schmelling, Michael; Schmidt, Burkhard; Schneider, Olivier; Schopper, Andreas; Schune, Marie Helene; Schwemmer, Rainer; Sciascia, Barbara; Sciubba, Adalberto; Semennikov, Alexander; Sepp, Indrek; Serra, Nicola; Serrano, Justine; Sestini, Lorenzo; Seyfert, Paul; Shapkin, Mikhail; Shapoval, Illya; Shcheglov, Yury; Shears, Tara; Shekhtman, Lev; Shevchenko, Vladimir; Shires, Alexander; Silva Coutinho, Rafael; Simi, Gabriele; Sirendi, Marek; Skidmore, Nicola; Skillicorn, Ian; Skwarnicki, Tomasz; Smith, Anthony; Smith, Edmund; Smith, Eluned; Smith, Jackson; Smith, Mark; Snoek, Hella; Sokoloff, Michael; Soler, Paul; Soomro, Fatima; Souza, Daniel; Souza De Paula, Bruno; Spaan, Bernhard; Sparkes, Ailsa; Spradlin, Patrick; Sridharan, Srikanth; Stagni, Federico; Stahl, Marian; Stahl, Sascha; Steinkamp, Olaf; Stenyakin, Oleg; Stevenson, Scott; Stoica, Sabin; Stone, Sheldon; Storaci, Barbara; Stracka, Simone; Straticiuc, Mihai; Straumann, Ulrich; Stroili, Roberto; Subbiah, Vijay Kartik; Sun, Liang; Sutcliffe, William; Swientek, Krzysztof; Swientek, Stefan; Syropoulos, Vasileios; Szczekowski, Marek; Szczypka, Paul; Szumlak, Tomasz; T'Jampens, Stephane; Teklishyn, Maksym; Tellarini, Giulia; Teubert, Frederic; Thomas, Christopher; Thomas, Eric; van Tilburg, Jeroen; Tisserand, Vincent; Tobin, Mark; Tolk, Siim; Tomassetti, Luca; Tonelli, Diego; Topp-Joergensen, Stig; Torr, Nicholas; Tournefier, Edwige; Tourneur, Stephane; Tran, Minh Tâm; Tresch, Marco; Tsaregorodtsev, Andrei; Tsopelas, Panagiotis; Tuning, Niels; Ubeda Garcia, Mario; Ukleja, Artur; Ustyuzhanin, Andrey; Uwer, Ulrich; Vacca, Claudia; Vagnoni, Vincenzo; Valenti, Giovanni; Vallier, Alexis; Vazquez Gomez, Ricardo; Vazquez Regueiro, Pablo; Vázquez Sierra, Carlos; Vecchi, Stefania; Velthuis, Jaap; Veltri, Michele; Veneziano, Giovanni; Vesterinen, Mika; Viaud, Benoit; Vieira, Daniel; Vieites Diaz, Maria; Vilasis-Cardona, Xavier; Vollhardt, Achim; Volyanskyy, Dmytro; Voong, David; Vorobyev, Alexey; Vorobyev, Vitaly; Voß, Christian; de Vries, Jacco; Waldi, Roland; Wallace, Charlotte; Wallace, Ronan; Walsh, John; Wandernoth, Sebastian; Wang, Jianchun; Ward, David; Watson, Nigel; Websdale, David; Whitehead, Mark; Wicht, Jean; Wiedner, Dirk; Wilkinson, Guy; Williams, Matthew; Williams, Mike; Wilschut, Hans; Wilson, Fergus; Wimberley, Jack; Wishahi, Julian; Wislicki, Wojciech; Witek, Mariusz; Wormser, Guy; Wotton, Stephen; Wright, Simon; Wyllie, Kenneth; Xie, Yuehong; Xing, Zhou; Xu, Zhirui; Yang, Zhenwei; Yuan, Xuhao; Yushchenko, Oleg; Zangoli, Maria; Zavertyaev, Mikhail; Zhang, Liming; Zhang, Wen Chao; Zhang, Yanxi; Zhelezov, Alexey; Zhokhov, Anatoly; Zhong, Liang; Zvyagin, Alexander

    2015-01-01

    The LHCb detector is a forward spectrometer at the Large Hadron Collider (LHC) at CERN. The experiment is designed for precision measurements of CP violation and rare decays of beauty and charm hadrons. In this paper the performance of the various LHCb sub-detectors and the trigger system are described, using data taken from 2010 to 2012. It is shown that the design criteria of the experiment have been met. The excellent performance of the detector has allowed the LHCb collaboration to publish a wide range of physics results, demonstrating LHCb's unique role, both as a heavy flavour experiment and as a general purpose detector in the forward region.

  11. ALFA Detector Control System

    CERN Document Server

    Oleiro Seabra, Luis Filipe; The ATLAS collaboration

    2015-01-01

    ALFA (Absolute Luminosity For ATLAS) is one of the sub-detectors of ATLAS/LHC. The ALFA system is composed by two stations installed in the LHC tunnel 240 m away from each side of the ATLAS interaction point. Each station has a vacuum and ventilation system, movement control and all the required electronic for signal processing. The Detector Control System (DCS) provides control and monitoring of several components and ensures the safe operation of the detector contributing to good Data Quality. This paper describes the ALFA DCS system including a detector overview, operation aspects and hardware control through a SCADA system, WinCC OA.

  12. Directed synthesis of stable large polyoxomolybdate spheres.

    Science.gov (United States)

    Roy, Soumyajit; Bossers, Lydia C A M; Meeldijk, Hans J D; Kuipers, Bonny W M; Kegel, Willem K

    2008-02-05

    Polyoxometalates or POMs, a class of inorganic transition metal-oxide based clusters, have gained significant interest owing to their catalytic, magnetic, and material science applications. All such applications require high surface area POM based materials. However, chemically synthesized POMs are still at most in the range of a few nanometers, with their size and morphology being difficult to control. Hence, there is an immediate need to develop design principles that allow easy control of POM morphology and size on mesoscopic (50-500 nm) length scales. Here, we report a design strategy to meet this need. Our method reported here avoids a complex chemical labyrinth by using a prefabricated cationic 1,2-dioleol-3-trimethylammonium-propane (DOTAP) vesicle as a scaffold/structure directing agent and gluing simple anionic heptamolybdates by electrostatic interaction and hydrogen bonds to form large POM spheres. By this method, complexity in the resulting structure can be deliberately induced either via the scaffold or via the oxometalate. The high degree of control in the matter of the size and morphology of the resulting POM superstructures renders this method attractive from a synthetic standpoint.

  13. Infinity-Norm Sphere-Decoding

    CERN Document Server

    Seethaler, Dominik

    2008-01-01

    The most promising approaches for efficient detection in multiple-input multiple-output (MIMO) wireless systems are based on sphere-decoding (SD). The conventional (and optimum) norm that is used to conduct the tree traversal step in SD is the l-two norm. It was, however, recently shown that using the l-infinity norm instead significantly reduces the VLSI implementation complexity of SD at only a marginal performance loss. These savings are due to a reduction in the length of the critical path and the silicon area of the circuit, but also, as observed previously through simulation results, a consequence of a reduction in the computational (algorithmic) complexity. The aim of this paper is an analytical performance and computational complexity analysis of l-infinity norm SD. For i.i.d. Rayleigh fading MIMO channels, we show that l-infinity norm SD achieves full diversity order with an asymptotic SNR gap, compared to l-two norm SD, that increases at most linearly in the number of receive antennas. Moreover, we ...

  14. Collective excitations in soft-sphere fluids.

    Science.gov (United States)

    Bryk, Taras; Gorelli, Federico; Ruocco, Giancarlo; Santoro, Mario; Scopigno, Tullio

    2014-10-01

    Despite that the thermodynamic distinction between a liquid and the corresponding gas ceases to exist at the critical point, it has been recently shown that reminiscence of gaslike and liquidlike behavior can be identified in the supercritical fluid region, encoded in the behavior of hypersonic waves dispersion. By using a combination of molecular dynamics simulations and calculations within the approach of generalized collective modes, we provide an accurate determination of the dispersion of longitudinal and transverse collective excitations in soft-sphere fluids. Specifically, we address the decreasing rigidity upon density reduction along an isothermal line, showing that the positive sound dispersion, an excess of sound velocity over the hydrodynamic limit typical for dense liquids, displays a nonmonotonic density dependence strictly correlated to that of thermal diffusivity and kinematic viscosity. This allows rationalizing recent observation parting the supercritical state based on the Widom line, i.e., the extension of the coexistence line. Remarkably, we show here that the extremals of transport properties such as thermal diffusivity and kinematic viscosity provide a robust definition for the boundary between liquidlike and gaslike regions, even in those systems without a liquid-gas binodal line. Finally, we discuss these findings in comparison with recent results for Lennard-Jones model fluid and with the notion of the "rigid-nonrigid" fluid separation lines.

  15. Quantum Hall effect on odd spheres

    Science.gov (United States)

    Coşkun, Ü. H.; Kürkçüoǧlu, S.; Toga, G. C.

    2017-03-01

    We solve the Landau problem for charged particles on odd dimensional spheres S2 k -1 in the background of constant SO (2 k -1 ) gauge fields carrying the irreducible representation (I/2 ,I/2 ,…,I/2 ). We determine the spectrum of the Hamiltonian, the degeneracy of the Landau levels and give the eigenstates in terms of the Wigner D -functions, and for odd values of I , the explicit local form of the wave functions in the lowest Landau level (LLL). The spectrum of the Dirac operator on S2 k -1 in the same gauge field background together with its degeneracies is also determined, and in particular, its number of zero modes is found. We show how the essential differential geometric structure of the Landau problem on the equatorial S2 k -2 is captured by constructing the relevant projective modules. For the Landau problem on S5, we demonstrate an exact correspondence between the union of Hilbert spaces of LLLs, with I ranging from 0 to Imax=2 K or Imax=2 K +1 to the Hilbert spaces of the fuzzy CP 3 or that of winding number ±1 line bundles over CP 3 at level K , respectively.

  16. Integrated marketing communications in educational sphere

    OpenAIRE

    2013-01-01

    The article investigates the paradigm of Integrated Marketing Communication and their main features. The author explains concept of Integrated Marketing Communication on the practical example in educational sphere. В статье рассказывается о понятии и основных чертах интегрированных маркетинговых коммуникаций. Автор поясняет положения концепции интегрированных маркетинговых коммуниакций на конкретном примере в образовательной сфере....

  17. Forming MOFs into spheres by use of molecular gastronomy methods.

    Science.gov (United States)

    Spjelkavik, Aud I; Aarti; Divekar, Swapnil; Didriksen, Terje; Blom, Richard

    2014-07-14

    A novel method utilizing hydrocolloids to prepare nicely shaped spheres of metal-organic frameworks (MOFs) has been developed. Microcrystalline CPO-27-Ni particles are dispersed in either alginate or chitosan solutions, which are added dropwise to solutions containing, respectively, either divalent group 2 cations or base that act as gelling agents. Well-shaped spheres are immediately formed, which can be dried into spheres containing mainly MOF (>95 wt %). The spheronizing procedures have been optimized with respect to maximum specific surface area, shape, and particle density of the final sphere. At optimal conditions, well-shaped 2.5-3.5 mm diameter CPO-27-Ni spheres with weight-specific surface areas <10 % lower than the nonformulated CPO-27-Ni precursor, and having sphere densities in the range 0.8 to 0.9 g cm(-3) and particle crushing strengths above 20 N, can be obtained. The spheres are well suited for use in fixed-bed catalytic or adsorption processes.

  18. Bubble entrapment during sphere impact onto quiescent liquid surfaces

    KAUST Repository

    Marston, Jeremy

    2011-06-20

    We report observations of air bubble entrapment when a solid sphere impacts a quiescent liquid surface. Using high-speed imaging, we show that a small amount of air is entrapped at the bottom tip of the impacting sphere. This phenomenon is examined across a broad range of impact Reynolds numbers, 0.2 a Re = (DU0/Il) a 1.2\\' 105. Initially, a thin air pocket is formed due to the lubrication pressure in the air layer between the sphere and the liquid surface. As the liquid surface deforms, the liquid contacts the sphere at a finite radius, producing a thin sheet of air which usually contracts to a nearly hemispherical bubble at the bottom tip of the sphere depending on the impact parameters and liquid properties. When a bubble is formed, the final bubble size increases slightly with the sphere diameter, decreases with impact speed but appears independent of liquid viscosity. In contrast, for the largest viscosities tested herein, the entrapped air remains in the form of a sheet, which subsequently deforms upon close approach to the base of the tank. The initial contact diameter is found to conform to scalings based on the gas Reynolds number whilst the initial thickness of the air pocket or adimplea scales with a Stokes\\' number incorporating the influence of the air viscosity, sphere diameter and impact speed and liquid density. © 2011 Cambridge University Press.

  19. Synthesis and Characterization of Oil-Chitosan Composite Spheres

    Directory of Open Access Journals (Sweden)

    Wei-Ting Wang

    2013-05-01

    Full Text Available Oil-chitosan composite spheres were synthesized by encapsulation of sunflower seed oil in chitosan droplets, dropping into NaOH solution and in situ solidification. Hydrophilic materials (i.e., iron oxide nanoparticles and lipophilic materials (i.e., rhodamine B or epirubicin could be encapsulated simultaneously in the spheres in a one step process. The diameters of the prepared spheres were 2.48 ± 0.11 mm (pure chitosan spheres, 2.31 ± 0.08 mm (oil-chitosan composites, 1.49 ± 0.15 mm (iron-oxide embedded oil-chitosan composites, and 1.69 ± 0.1 mm (epirubicin and iron oxide encapsulated oil-chitosan composites, respectively. Due to their superparamagnetic properties, the iron-oxide embedded oil-chitosan composites could be guided by a magnet. A lipophilic drug (epirubicin could be loaded in the spheres with encapsulation rate measured to be 72.25%. The lipophilic fluorescent dye rhodamine B was also loadable in the spheres with red fluorescence being observed under a fluorescence microscope. We have developed a novel approach to an in situ process for fabricating oil-chitosan composite spheres with dual encapsulation properties, which are potential multifunctional drug carriers.

  20. Synthesis and characterization of oil-chitosan composite spheres.

    Science.gov (United States)

    Huang, Keng-Shiang; Wang, Chih-Yu; Yang, Chih-Hui; Grumezescu, Alexandru Mihai; Lin, Yung-Sheng; Kung, Chao-Pin; Lin, I-Yin; Chang, Yi-Ching; Weng, Wei-Jie; Wang, Wei-Ting

    2013-05-16

    Oil-chitosan composite spheres were synthesized by encapsulation of sunflower seed oil in chitosan droplets, dropping into NaOH solution and in situ solidification. Hydrophilic materials (i.e., iron oxide nanoparticles) and lipophilic materials (i.e., rhodamine B or epirubicin) could be encapsulated simultaneously in the spheres in a one step process. The diameters of the prepared spheres were 2.48 ± 0.11 mm (pure chitosan spheres), 2.31 ± 0.08 mm (oil-chitosan composites), 1.49 ± 0.15 mm (iron-oxide embedded oil-chitosan composites), and 1.69 ± 0.1 mm (epirubicin and iron oxide encapsulated oil-chitosan composites), respectively. Due to their superparamagnetic properties, the iron-oxide embedded oil-chitosan composites could be guided by a magnet. A lipophilic drug (epirubicin) could be loaded in the spheres with encapsulation rate measured to be 72.25%. The lipophilic fluorescent dye rhodamine B was also loadable in the spheres with red fluorescence being observed under a fluorescence microscope. We have developed a novel approach to an in situ process for fabricating oil-chitosan composite spheres with dual encapsulation properties, which are potential multifunctional drug carriers.

  1. Public sphere as assemblage: the cultural politics of roadside memorialization.

    Science.gov (United States)

    Campbell, Elaine

    2013-09-01

    This paper investigates contemporary academic accounts of the public sphere. In particular, it takes stock of post-Habermasian public sphere scholarship, and acknowledges a lively and variegated debate concerning the multiple ways in which individuals engage in contemporary political affairs. A critical eye is cast over a range of key insights which have come to establish the parameters of what 'counts' as a/the public sphere, who can be involved, and where and how communicative networks are established. This opens up the conceptual space for re-imagining a/the public sphere as an assemblage. Making use of recent developments in Deleuzian-inspired assemblage theory - most especially drawn from DeLanda's (2006) 'new philosophy of society' - the paper sets out an alternative perspective on the notion of the public sphere, and regards it as a space of connectivity brought into being through a contingent and heterogeneous assemblage of discursive, visual and performative practices. This is mapped out with reference to the cultural politics of roadside memorialization. However, a/the public sphere as an assemblage is not simply a 'social construction' brought into being through a logic of connectivity, but is an emergent and ephemeral space which reflexively nurtures and assembles the cultural politics (and political cultures) of which it is an integral part. The discussion concludes, then, with a consideration of the contribution of assemblage theory to public sphere studies. (Also see Campbell 2009a).

  2. Radar Imaging of Spheres in 3D using MUSIC

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, D H; Berryman, J G

    2003-01-21

    We have shown that multiple spheres can be imaged by linear and planar EM arrays using only one component of polarization. The imaging approach involves calculating the SVD of the scattering response matrix, selecting a subset of singular values that represents noise, and evaluating the MUSIC functional. The noise threshold applied to the spectrum of singular values for optimal performance is typically around 1%. The resulting signal subspace includes more than one singular value per sphere. The presence of reflections from the ground improves height localization, even for a linear array parallel to the ground. However, the interference between direct and reflected energy modulates the field, creating periodic nulls that can obscure targets in typical images. These nulls are largely eliminated by normalizing the MUSIC functional with the broadside beam pattern of the array. The resulting images show excellent localization for 1 and 2 spheres. The performance for the 3 sphere configurations are complicated by shadowing effects and the greater range of the 3rd sphere in case 2. Two of the three spheres are easily located by MUSIC but the third is difficult to distinguish from other local maxima of the complex imaging functional. Improvement is seen when the linear array is replace with a planar array, which increases the effective aperture height. Further analysis of the singular values and their relationship to modes of scattering from the spheres, as well as better ways to exploit polarization, should improve performance. Work along these lines is currently being pursued by the authors.

  3. Calibration of the JEM-EUSO detector

    Directory of Open Access Journals (Sweden)

    Gorodetzky P.

    2013-06-01

    Full Text Available In order to unveil the mystery of ultra high energy cosmic rays (UHECRs, JEM-EUSO (Extreme Universe Space Observatory on-board Japan Experiment Module will observe extensive air showers induced by UHECRs from the International Space Station orbit with a huge acceptance. Calibration of the JEM-EUSO instrument, which consists of Fresnel optics and a focal surface detector with 5000 photomultipliers, is very important to discuss the origin of UHECRs precisely with the observed results. In this paper, the calibration before launch and on-orbit is described. The calibration before flight will be performed as precisely as possible with integrating spheres. In the orbit, the relative change of the performance will be checked regularly with on-board and on-ground light sources. The absolute calibration of photon detection efficiency may be performed with the moon, which is a stable light source in the nature.

  4. Generation of Spheres from Dental Epithelial Stem Cells

    Science.gov (United States)

    Natsiou, Despoina; Granchi, Zoraide; Mitsiadis, Thimios A.; Jimenez-Rojo, Lucia

    2017-01-01

    The in vitro three-dimensional sphere model has already been established as an important tool in fundamental sciences. This model facilitates the study of a variety of biological processes including stem cell/niche functions and tissue responses to injury and drugs. Here we describe the complete protocol for the in vitro formation of spheres originated from the epithelium of rodent incisors. In addition, we show that in these spheres cell proliferation is maintained, as well as the expression of several key molecules characterizing stem cells such as Sox2 and p63. These epithelial dentospheres could be used as an in vitro model system for stem cell research purposes. PMID:28154538

  5. Oscillation effects upon film boiling from a sphere.

    Science.gov (United States)

    Schmidt, W. E.; Witte, L. C.

    1972-01-01

    Heat transfer rates from a silver-plated copper sphere, 0.75 in. in diameter, were studied by high speed photography during oscillations of the sphere in saturated liquid nitrogen and Freon-11. The oscillation frequencies ranged from zero to 13 Hz, and the amplitude-to-diameter ratio varied from zero to 2.67. The sphere was supported by a thin-walled stainless steel tube and carried a thermocouple attached near the lower stagnation point. A Fastax WF-3 16mm movie camera was used at about 2000 frames/sec. The differences in the vapor removal process at lower and higher oscillation frequencies are discussed.

  6. Spherical interferometry for the characterization of precision spheres

    Science.gov (United States)

    Nicolaus, R. A.; Bartl, G.

    2016-09-01

    Interferometry with spherical wavefronts is usually used for characterizing precise optics. A special spherical interferometer was set up to measure the volume of high precision spheres used for the new definition of the SI unit kilogram, for which a fundamental constant, such as Planck’s constant h or Avogadro’s constant N A, was to be determined. Furthermore with this type of interferometer and with a special evaluating algorithm, absolute form deviations of spheres can be determined. With this knowledge, a sphere can be processed further to reach unrivaled small sphericity deviations.

  7. From Ewald sphere to Ewald shell in nonlinear optics

    Science.gov (United States)

    Huang, Huang; Huang, Cheng-Ping; Zhang, Chao; Hong, Xu-Hao; Zhang, Xue-Jin; Qin, Yi-Qiang; Zhu, Yong-Yuan

    2016-07-01

    Ewald sphere is a simple vector scheme to depict the X-ray Bragg diffraction in a crystal. A similar method, known as the nonlinear Ewald sphere, was employed to illustrate optical frequency conversion processes. We extend the nonlinear Ewald sphere to the Ewald shell construction. With the Ewald shell, a variety of quasi-phase-matching (QPM) effects, such as the collective envelope effect associated with multiple QPM resonances, the enhanced second- harmonic generation due to multiple reciprocal vectors etc., are suggested theoretically and verified experimentally. By rotating the nonlinear photonic crystal sample, the dynamic evolution of these QPM effects has also been observed, which agreed well with the Ewald shell model.

  8. Simulations of a supersymmetry inspired model on a fuzzy sphere

    Energy Technology Data Exchange (ETDEWEB)

    Volkholz, J. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Bietenholz, W. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2007-11-15

    We present a numerical study of a two dimensional model of the Wess-Zumino type. We formulate this model on a sphere, where the fields are expanded in spherical harmonics. The sphere becomes fuzzy by a truncation in the angular momenta. This leads to a finite set of degrees of freedom without explicitly breaking the space symmetries. The corresponding field theory is expressed in terms of a matrix model, which can be simulated. We present first numerical results for the phase structure of a variant of this model on a fuzzy sphere. The prospect to restore exact supersymmetry in certain limits is under investigation. (orig.)

  9. Stochastic hard-sphere dynamics for hydrodynamics of nonideal fluids.

    Science.gov (United States)

    Donev, Aleksandar; Alder, Berni J; Garcia, Alejandro L

    2008-08-15

    A novel stochastic fluid model is proposed with a nonideal structure factor consistent with compressibility, and adjustable transport coefficients. This stochastic hard-sphere dynamics (SHSD) algorithm is a modification of the direct simulation Monte Carlo algorithm and has several computational advantages over event-driven hard-sphere molecular dynamics. Surprisingly, SHSD results in an equation of state and a pair correlation function identical to that of a deterministic Hamiltonian system of penetrable spheres interacting with linear core pair potentials. The fluctuating hydrodynamic behavior of the SHSD fluid is verified for the Brownian motion of a nanoparticle suspended in a compressible solvent.

  10. Self-diffusion in liquid gallium and hard sphere model

    Directory of Open Access Journals (Sweden)

    Blagoveshchenskii Nikolay

    2015-01-01

    Full Text Available Incoherent and coherent components of quasielastic neutron scattering have been studied in the temperature range of T = 313 K – 793 K aiming to explore the applicability limits of the hard-sphere approach for the microscopic dynamics of liquid gallium, which is usually considered as a non-hard-sphere system. It was found that the non-hard-sphere effects come into play at the distances shorter than the average interatomic distance. The longer range diffusive dynamics of liquid Ga is dominated by the repulsive forces between the atoms.

  11. VMware vSphere 4 Administration Instant Reference

    CERN Document Server

    Lowe, Scott; Johnson, Matthew K

    2009-01-01

    The only quick reference guide to the number one virtualization product!. Get all your solutions about VMware's newest virtualization infrastructure software on the spot with this handy reference guide. Designed for quick access with special headings, thumb tabs, easy-to-read lists, and more, this book is the perfect companion to any comprehensive VMware guide, such as Mastering VMware vSphere 4 .: Covers the market-leading virtualization product, VMware's new vSphere 4; Offers a quick-access reference for your day-to-day administration of vSphere 4; Includes thumb tabs, secondary and tertiary

  12. Mastering VMware vSphere 5.5

    CERN Document Server

    Lowe, Scott; Guthrie, Forbes; Liebowitz, Matt; Atwell, Josh

    2013-01-01

    The 2013 edition of the bestselling vSphere book on the market Virtualization remains the hottest trend in the IT world, and VMware vSphere is the industry's most widely deployed virtualization solution. The demand for IT professionals skilled in virtualization and cloud-related technologies is great and expected to keep growing. This comprehensive Sybex guide covers all the features and capabilities of VMware vSphere, showing administrators step by step how to install, configure, operate, manage, and secure it. This perfect blend of hands-on instruction, conceptual explanation, and practic

  13. Pixel detector readout chip

    CERN Multimedia

    1991-01-01

    Close-up of a pixel detector readout chip. The photograph shows an aera of 1 mm x 2 mm containing 12 separate readout channels. The entire chip contains 1000 readout channels (around 80 000 transistors) covering a sensitive area of 8 mm x 5 mm. The chip has been mounted on a silicon detector to detect high energy particles.

  14. ALICE Silicon Strip Detector

    CERN Multimedia

    Nooren, G

    2013-01-01

    The Silicon Strip Detector (SSD) constitutes the two outermost layers of the Inner Tracking System (ITS) of the ALICE Experiment. The SSD plays a crucial role in the tracking of the particles produced in the collisions connecting the tracks from the external detectors (Time Projection Chamber) to the ITS. The SSD also contributes to the particle identification through the measurement of their energy loss.

  15. ALICE Photon Multiplicity Detector

    CERN Multimedia

    Nayak, T

    2013-01-01

    Photon Multiplicity Detector (PMD) measures the multiplicity and spatial distribution of photons in the forward region of ALICE on a event-by-event basis. PMD is a pre-shower detector having fine granularity and full azimuthal coverage in the pseudo-rapidity region 2.3 < η < 3.9.

  16. Detector Systems at CLIC

    CERN Document Server

    Simon, Frank

    2011-01-01

    The Compact Linear Collider CLIC is designed to deliver e+e- collisions at a center of mass energy of up to 3 TeV. The detector systems at this collider have to provide highly efficient tracking and excellent jet energy resolution and hermeticity for multi-TeV final states with multiple jets and leptons. In addition, the detector systems have to be capable of distinguishing physics events from large beam-induced background at a crossing frequency of 2 GHz. Like for the detector concepts at the ILC, CLIC detectors are based on event reconstruction using particle flow algorithms. The two detector concepts for the ILC, ILD and SID, were adapted for CLIC using calorimeters with dense absorbers limiting leakage through increased compactness, as well as modified forward and vertex detector geometries and precise time stamping to cope with increased background levels. The overall detector concepts for CLIC are presented, with particular emphasis on the main detector and engineering challenges, such as: the ultra-thi...

  17. The LDC detector concept

    Indian Academy of Sciences (India)

    Ties Behnke; LDC Concept Group

    2007-11-01

    In preparation of the experimental program at the international linear collider (ILC), the large detector concept (LDC) is being developed. The main points of the LDC are a large volume gaseous tracking system, combined with high precision vertex detector and an extremely granular calorimeter. The main design force behind the LDC is the particle flow concept.

  18. CMS Detector Posters

    CERN Multimedia

    2016-01-01

    CMS Detector posters (produced in 2000): CMS installation CMS collaboration From the Big Bang to Stars LHC Magnetic Field Magnet System Trackering System Tracker Electronics Calorimetry Eletromagnetic Calorimeter Hadronic Calorimeter Muon System Muon Detectors Trigger and data aquisition (DAQ) ECAL posters (produced in 2010, FR & EN): CMS ECAL CMS ECAL-Supermodule cooling and mechatronics CMS ECAL-Supermodule assembly

  19. Simulation and optimisation of a position sensitive scintillation detector with wavelength shifting fibers for thermal neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Herzkamp, Matthias; Engels, Ralf; Kemmerling, Guenter [ZEA-2, Forschungszentrum Juelich (Germany); Brueckel, Thomas [JCNS, Forschungszentrum Juelich (Germany); Stahl, Achim [III. Physikalisches Institut B, RWTH Aachen (Germany); Waasen, Stefan van [ZEA-2, Forschungszentrum Juelich (Germany); Faculty of Engineering, University of Duisburg-Essen (Germany)

    2015-07-01

    In neutron scattering experiments it is important to have position sensitive large scale detectors for thermal neutrons. A detector based on a neutron scintillator with wave length shifting fibers is a new kind of such a detector. We present the simulation of the detector based on the microscopic structure of the scintillation material of the mentioned detector. It consists of a converter and a scintillation powder bound in a matrix. The converter in our case is lithium fluoride with enriched lithium 6, to convert thermal neutrons into high energetic alpha and triton particles. The scintillation material is silver doped zinc sulfide. We show that pulse height spectra obtained by these scintillators can be be explained by the simple model of randomly distributed spheres of zinc sulfide and lithium fluoride. With this model, it is possible to optimise the mass ratio of zinc sulfide to lithium fluoride with respect to detection efficiency and/or energy deposition in zinc sulfide.

  20. The PERDaix detector

    Energy Technology Data Exchange (ETDEWEB)

    Bachlechner, Andreas; Beischer, Bastian; Greim, Roman [I. Physikalisches Institut B, RWTH Aachen University, Aachen 52056 (Germany); Kirn, Thomas, E-mail: kirn@physik.rwth-aachen.de [I. Physikalisches Institut B, RWTH Aachen University, Aachen 52056 (Germany); Mai, Carsten; Yearwood, Gregorio Roper; Schael, Stefan; Schug, David; Tholen, Heiner; Wienkenhoever, Jens [I. Physikalisches Institut B, RWTH Aachen University, Aachen 52056 (Germany)

    2012-12-11

    The PERDaix (Proton Electron Radiation Detector Aix-la-Chapelle) detector is designed to measure charged particles in cosmic rays. It can distinguish particle species up to 5 GV rigidity. PERDaix was flown on the BEXUS-11 balloon on 23rd November 2010. The detector has the dimensions of 246 Multiplication-Sign 400 Multiplication-Sign 859 mm{sup 3}, a geometrical acceptance of 32 cm{sup 2}sr, a low weight of 40 kg and a low power consumption of 60 W. The spectrometer consists of a time-of-flight system, a scintillating fiber tracking detector, a permanent magnet and a transition radiation detector. Silicon photomultipliers are used as photodetectors in the time-of-flight and the tracker system.

  1. The PERDaix detector

    Science.gov (United States)

    Bachlechner, Andreas; Beischer, Bastian; Greim, Roman; Kirn, Thomas; Mai, Carsten; Yearwood, Gregorio Roper; Schael, Stefan; Schug, David; Tholen, Heiner; Wienkenhöver, Jens

    2012-12-01

    The PERDaix (Proton Electron Radiation Detector Aix-la-Chapelle) detector is designed to measure charged particles in cosmic rays. It can distinguish particle species up to 5 GV rigidity. PERDaix was flown on the BEXUS-11 balloon on 23rd November 2010. The detector has the dimensions of 246×400×859 mm3, a geometrical acceptance of 32 cm2sr, a low weight of 40 kg and a low power consumption of 60 W. The spectrometer consists of a time-of-flight system, a scintillating fiber tracking detector, a permanent magnet and a transition radiation detector. Silicon photomultipliers are used as photodetectors in the time-of-flight and the tracker system.

  2. ATLAS ITk Pixel detector

    CERN Document Server

    Gemme, Claudia; The ATLAS collaboration

    2016-01-01

    The high luminosity upgrade of the LHC (HL-LHC) in 2026 will provide new challenge to the ATLAS tracker. The current inner detector will be replaced with a whole silicon tracker which will consist of a five barrel layer Pixel detector surrounded by a four barrel layer Strip detector. The expected high radiation level are requiring the development of upgraded silicon sensors as well as new a front-end chip. The dense tracking environment will require finer granularity detectors. The data rates will require new technologies for high bandwidth data transmission and handling. The current status of the HL-LHC ATLA Pixel detector developments as well as the various layout options will be reviewed.

  3. TIDALLY DRIVEN DYNAMOS IN A ROTATING SPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Cébron, D.; Hollerbach, R., E-mail: david.cebron@ujf-grenoble.fr, E-mail: r.hollerbach@leeds.ac.uk [Institut für Geophysik, Sonneggstrasse 5, ETH Zürich, Zürich CH-8092 (Switzerland)

    2014-07-01

    Large-scale planetary or stellar magnetic fields generated by a dynamo effect are mostly attributed to flows forced by buoyancy forces in electrically conducting fluid layers. However, these large-scale fields may also be controlled by tides, as previously suggested for the star τ-boo, Mars, or the early Moon. By simulating a small local patch of a rotating fluid, Barker and Lithwick have recently shown that tides can drive small-scale dynamos by exciting a hydrodynamic instability, the so-called elliptical (or tidal) instability. By performing global magnetohydrodynamic simulations of a rotating spherical fluid body, we investigate if this instability can also drive the observed large-scale magnetic fields. We are thus interested in the dynamo threshold and the generated magnetic field in order to test if such a mechanism is relevant for planets and stars. Rather than solving the problem in a geometry deformed by tides, we consider a spherical fluid body and add a body force to mimic the tidal deformation in the bulk of the fluid. This allows us to use an efficient spectral code to solve the magnetohydrodynamic problem. We first compare the hydrodynamic results with theoretical asymptotic results and numerical results obtained in a truly deformed ellipsoid, which confirms the presence of elliptical instability. We then perform magnetohydrodynamic simulations and investigate the dynamo capability of the flow. Kinematic and self-consistent dynamos are finally simulated, showing that the elliptical instability is capable of generating a dipole-dominated large-scale magnetic field in global simulations of a fluid rotating sphere.

  4. Ensuring Economic Security in Lending Sphere

    Directory of Open Access Journals (Sweden)

    Ivan Vadimovich Kochikin

    2016-06-01

    Full Text Available Relevance of the topic is determined by the need for sustainable development of the country’s banking system, capable of ensuring the process of raising funds to producers and the public for their projects. One of the implementation of this objective is to discourage unfair behavior in financial markets. Trust is a key factor in the development of financial markets, therefore it is necessary to suppress the appearance of unfair practices and participants – black creditors, falsification of financial statements, trading on insider information and market manipulation. It requires a whole range of activities, and above all ensuring the inevitability and proportionality of punishment for unscrupulous players, the introduction of requirements for the business reputation of the management of financial institutions.The article is devoted to structuring legal violations in the lending sphere. The analysis of indicators of credit organizations in Russia was conducted to fulfill this aim. This analysis revealed the causes of sustainable growth of overdue accounts payable – job cuts in enterprises, violations in the financial sector, various errors in the credit granting / raising. The authors carry out the systematization and classification of offenses in the area of lending, provide examples, as well as factual material illustrating the violations in the lending process having the characteristics of a fraud. The article substantiates the obligations of employees of the credit institution, in the result of which risks of granting credit to fraudsters can be reduced. The methods of fraud prevention should include the identified methods of protection against fraud in the area under consideration – exchange of information by banks associated with the criminal intentions of customers; technology development and technical support, training, and personnel responsibilities.

  5. [The power of religion in the public sphere] / Alar Kilp

    Index Scriptorium Estoniae

    Kilp, Alar, 1969-

    2012-01-01

    Arvustus: Buthler, Judith, Habermas, Jürgen, Taylor, Charles, West, Cornel. The power of religion in the public sphere. (Eduardo Mendieta, Jonathan VanAntwerpen (eds.) Afterword by Craig Calhoun.) New York ; Chichester : Columbia University Press, 2011

  6. An elastic two-sphere swimmer in Stokes flow

    CERN Document Server

    Nasouri, Babak; Elfring, Gwynn J

    2016-01-01

    Swimming at low Reynolds number in Newtonian fluids is only possible through non-reciprocal body deformations due to the kinematic reversibility of the Stokes equations. We consider here a model swimmer consisting of two linked spheres, wherein one sphere is rigid and the other an incompressible neo-Hookean solid. The two spheres are connected by a rod which changes its length periodically. We show that the deformations of the body are non-reciprocal despite the reversible actuation and hence, the elastic two-sphere swimmer propels forward. Our results indicate that even weak elastic deformations of a body can qualitatively alter swimming dynamics and should not be neglected in analyzing swimming in Stokes flows.

  7. An elastic two-sphere swimmer in Stokes flow

    Science.gov (United States)

    Nasouri, Babak; Elfring, Gwynn

    2016-11-01

    Swimming at low Reynolds number in Newtonian fluids is only possible through non-reciprocal body deformations due to the kinematic reversibility of the Stokes equations. We consider here a model swimmer consisting of two linked spheres, wherein one sphere is rigid and the other an incompressible neo-Hookean solid. The two spheres are connected by a rod which changes its length periodically. We show that the deformations of the body are non-reciprocal despite the reversible actuation and hence, the elastic two-sphere swimmer propels forward. Our results indicate that even weak elastic deformations of a body can qualitatively alter swimming dynamics and should not be neglected in analyzing swimming in Stokes flows.

  8. Synthesis of Nanometer-sized Mesoporous Oxide Spheres

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A few hundreds nanometer-sized mesoporous silica and alumina spheres were synthesized in organic solvents. The impacts of ammonia, N,N-dimethylformamide (DMF) and stirring speed were also investigated.

  9. A Breakthrough in Sphere Packing: The Search for Magic Functions

    NARCIS (Netherlands)

    Laat, D. de; Vallentin, F.

    2016-01-01

    This paper by David de Laat and Frank Vallentin is an exposition about the two recent breakthrough results in the theory of sphere packings. It includes an interview with Henry Cohn, Abhinav Kumar, Stephen D. Miller and Maryna Viazovska.

  10. Numerical simulation of negative Magnus force on a rotating sphere

    Science.gov (United States)

    Muto, Masaya; Tsubokura, Makoto; Oshima, Nobuyuki

    2010-11-01

    Flow characteristics and fluid force on a sphere rotating along with axis perpendicular to mean air flow were investigated using Large Eddy Simulation at two different Reynolds numbers of 10,000 and 200,000. As a result of simulation, opposite flow characteristics around the sphere and displacement of the separation point were visualized depending on the Reynolds number even though the sphere rotates at the same rotation speed according to the Reynolds number. When Reynolds number is 10,000, flow characteristics agree with the flow field explained in the Magnus effect. However sphere rotates at the same rotation speed while increasing Reynolds number to 200,000, separation point moves in opposite direction and wake appears in the different direction. The reason of the negative Magnus force was discussed in terms of the boundary layer transition on the surface.

  11. Dynamic equivalences in the hard-sphere dynamic universality class.

    Science.gov (United States)

    López-Flores, Leticia; Ruíz-Estrada, Honorina; Chávez-Páez, Martín; Medina-Noyola, Magdaleno

    2013-10-01

    We perform systematic simulation experiments on model systems with soft-sphere repulsive interactions to test the predicted dynamic equivalence between soft-sphere liquids with similar static structure. For this we compare the simulated dynamics (mean squared displacement, intermediate scattering function, α-relaxation time, etc.) of different soft-sphere systems, between them and with the hard-sphere liquid. We then show that the referred dynamic equivalence does not depend on the (Newtonian or Brownian) nature of the microscopic laws of motion of the constituent particles, and hence, applies independently to colloidal and to atomic simple liquids. Finally, we verify another more recently proposed dynamic equivalence, this time between the long-time dynamics of an atomic liquid and its corresponding Brownian fluid (i.e., the Brownian system with the same interaction potential).

  12. The Blaschke conjecture and great circle fibrations of spheres

    OpenAIRE

    2001-01-01

    We construct an explicit diffeomorphism taking any fibration of a sphere by great circles into the Hopf fibration, using elementary geometry--indeed the diffeomorphism is a local (differential) invariant, algebraic in derivatives.

  13. Method for producing dustless graphite spheres from waste graphite fines

    Science.gov (United States)

    Pappano, Peter J; Rogers, Michael R

    2012-05-08

    A method for producing graphite spheres from graphite fines by charging a quantity of spherical media into a rotatable cylindrical overcoater, charging a quantity of graphite fines into the overcoater thereby forming a first mixture of spherical media and graphite fines, rotating the overcoater at a speed such that the first mixture climbs the wall of the overcoater before rolling back down to the bottom thereby forming a second mixture of spherical media, graphite fines, and graphite spheres, removing the second mixture from the overcoater, sieving the second mixture to separate graphite spheres, charging the first mixture back into the overcoater, charging an additional quantity of graphite fines into the overcoater, adjusting processing parameters like overcoater dimensions, graphite fines charge, overcoater rotation speed, overcoater angle of rotation, and overcoater time of rotation, before repeating the steps until graphite fines are converted to graphite spheres.

  14. A Reaction Sphere for High Performance Attitude Control Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Our innovative reaction sphere (Doty pending patent application serial number 61/164,868) has the potential to provide much higher performance than a conventional...

  15. ANOMIE DEVELOPMENT IN RELIGIOUS SPHERE OF POSTSOVIET SOCIETY

    Directory of Open Access Journals (Sweden)

    Pletnev Alexander Vladislavovich

    2013-04-01

    Full Text Available In the current article the author analyzes influence of amendments in the religious sphere of postsoviet society for the increase of anomie in it. He indicates main factors that influence the anomie and charactarize specific features of religious sphere of modern Russian society. They are religious variety, caused by missionery activity and restore of traditional confessions (Orthodox, Islam, Judiasm, Buddism, Lutheranism, and also actualization of the religious identity matter, the phenomen of “out of confession herecy” and religious conflicts. According to the researcher opinion, amendments in the spiritual sphere influence the studied phenomen as well as trasnformation of political and economic system, caused by transfer from communism to democracy and from planning to market economy. The possible ways of anomie decrease via religious sphere of the society such as increase of Orthodox church belivers, adaptation of its tradition and practics, new religious cult inctitualization are indicated in this article as well.

  16. Experimental evidence of zero forward scattering by magnetic spheres.

    Science.gov (United States)

    Mehta, R V; Patel, Rajesh; Desai, Rucha; Upadhyay, R V; Parekh, Kinnari

    2006-03-31

    Magnetically induced diffraction patterns by micron sized magnetic spheres dispersed in a ferrofluid disappear at a certain critical magnetic field. This critical field is found to depend on the concentration of the ferrofluid and on the volume of the magnetic spheres. We attribute this effect to the zero forward scattering by magnetic spheres as predicted by Kerker, Wang, and Giles [J. Opt. Soc. Am. 73, 765 (1983)]. We suggest that such a dispersion can be used to study the optical analogues of localization of electrons in condensed matter, the Hall effect, and the anisotropic diffusion, etc. The combination of the micron sized magnetic spheres and the ferrofluid will also be useful to design magnetically tunable photonic devices.

  17. Forces encountered by a sphere during impact into sand

    Science.gov (United States)

    Joubaud, Sylvain; Homan, Tess; Gasteuil, Y.; Lohse, Detlef; van der Meer, Devaraj

    2014-12-01

    We describe direct measurements of the acceleration of an object impacting on a loosely packed granular bed under various pressures, using an instrumented sphere. The sphere acts as a noninvasive probe that measures and continuously transmits the acceleration as it penetrates into the sand, using a radio signal. The time-resolved acceleration of the sphere reveals the detailed dynamics during the impact that cannot be resolved from the position information alone. Because of the unobstructed penetration, we see a downward acceleration of the sphere at the moment the air cavity collapses. The compressibility of the sand bed is observed through the oscillatory behavior of the acceleration curve for various ambient pressures; it shows the influence of interstitial air on the compaction of the sand as a function of time.

  18. Phonon contribution to the entropy of hard-sphere crystals.

    Science.gov (United States)

    Elser, Veit

    2014-05-01

    Comparing the entropies of hard spheres in the limit of close packing, for different stacking sequences of the hexagonal layers, has been a challenge because the differences are so small. Here we present a method based on a "sticky-sphere" model by which the system interpolates between hard spheres in one limit and a harmonic crystal in the other. For the fcc and hcp stackings we have calculated the entropy difference in the harmonic (sticky) limit, as well as the differences in the free energy change upon removing the stickiness in the model. The former, or phonon entropy, accounts for most of the entropy difference. Our value for the net entropy difference, Δs = 0.001164(8)k(B) per sphere, is in excellent agreement with the best previous estimate by Mau and Huse [Phys. Rev. E 59, 4396 (1999)].

  19. On isometric extension problem between two unit spheres

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper we introduce the isometric extension problem of isometric mappings between two unit spheres. Some important results of the related problems are outlined and the recent progress is mentioned.

  20. On isometric extension problem between two unit spheres

    Institute of Scientific and Technical Information of China (English)

    Ding GuangGui

    2009-01-01

    In this paper we introduce the isometric extension problem of isometric mappings between two unit spheres.Some important results of the related problems are outlined and the recent progress is mentioned.

  1. Diffusive Wave Spectroscopy of a random close packing of spheres

    Science.gov (United States)

    Crassous, J.

    2007-06-01

    We are interested in the propagation of light in a random packing of dielectric spheres within the geometrical optics approximation. Numerical simulations are performed using a ray tracing algorithm. The effective refractive indexes and the transport mean free path are computed for different refractive indexes of spheres and intersticial media. The variations of the optical path length under small deformations of the spheres assembly are also computed and compared to the results of Diffusive Wave Spectroscopy experiments. Finally, we propose a measure of the transport mean free path and a Diffusive Wave Spectroscopy experiment on a packing of glass spheres. The results of those experiments agree with the predictions of this ray tracing approach.

  2. The Volume of a Sphere: A Chinese Derivation.

    Science.gov (United States)

    Swetz, Frank J.

    1995-01-01

    Examines how ancient Chinese mathematicians attempted to correct an error concerning the volume of a sphere in the Nine Chapters on the Mathematical Art, a compendium of the mathematics known and used in China in ancient times. (MKR)

  3. Wind speed and direction measurements using the sphere anemometer

    Science.gov (United States)

    Heisselmann, Hendrik; Hoelling, Michael; Peinke, Joachim

    2009-11-01

    In times of growing energy demand, the importance of wind energy is rapidly increasing and so is the need for accurate wind speed and direction measurements. The widely spread cup anemometers show significant over-speeding under turbulent wind conditions as inherent in atmospherical flows while being solely capable of detecting the wind speed. Therefore, we propose the newly developed sphere anemometer as a simple an robust sensor for direction and velocity measurements. The sphere anemometer exploits the velocity-dependent deflection of a tube, which is the order of μm and can be detected by means of a light pointer as used in atomic force microscopes. In comparative measurements under laboratory conditions the sphere anemometer showed a significantly higher temporal resolution then cup anemometers while it does not exhibit any over-speeding. Additionally, results of atmospherical wind measurements with the sphere anemometer and state-of-the-art cup anemometry are presented.

  4. Satellite Relative Motion Control for MIT’s SPHERES Program

    Science.gov (United States)

    2012-03-01

    firing combinations of its twelve cold gas thrusters [2]. These thrusters either fire at a specific value or they do not fire at all. This on-off...Satellite Relative Motion Control for MIT’s SPHERES Program THESIS Samuel P. Barbaro, Second Lieutenant, USAF AFIT/ GA /ENY/12-M02 DEPARTMENT OF THE...United States. AFIT/ GA /ENY/12-M02 Satellite Relative Motion Control for MIT’s SPHERES Program THESIS Presented to the Faculty Department of

  5. Sphere Lower Bound for Rotated Lattice Constellations in Fading Channels

    CERN Document Server

    Fabregas, Albert Guillen i

    2007-01-01

    We study the error probability performance of rotated lattice constellations in frequency-flat Nakagami-$m$ block-fading channels. In particular, we use the sphere lower bound on the underlying infinite lattice as a performance benchmark. We show that the sphere lower bound has full diversity. We observe that optimally rotated lattices with largest known minimum product distance perform very close to the lower bound, while the ensemble of random rotations is shown to lack diversity and perform far from it.

  6. Magnetic relaxation in chain-of-spheres ferromagnetic particles

    CERN Document Server

    Yang, J S

    2002-01-01

    The thermal activation of elongated ferromagnetic particles is analyzed using a chain-of-spheres model. The spheres within the chain are assumed to be coupled magnetically with dipolar interaction. The effect of uniaxial magnetocrystalline anisotropy along the chain is also taken into account. It was shown that the behavior of thermal switching critically depends on the relative strength of shape anisotropy and magnetocrystalline anisotropy, field orientation, sweep field rate and temperature.

  7. Silica hollow spheres with nano-macroholes like diatomaceous earth.

    Science.gov (United States)

    Fujiwara, Masahiro; Shiokawa, Kumi; Sakakura, Ikuko; Nakahara, Yoshiko

    2006-12-01

    Artificial synthesis of hollow cell walls of diatoms is an ultimate target of nanomaterial science. The addition of some water-soluble polymers such as sodium polymethacrylate to a solution of water/oil/water emulsion system, which is an essential step of the simple synthetic procedure of silica hollow spheres (microcapsules), led to the formation of silica hollow spheres with nano-macroholes (>100 nm) in their shell walls, the morphologies of which are analogous to those of diatom earth.

  8. Low Velocity Sphere Impact of a Soda Lime Silicate Glass

    Energy Technology Data Exchange (ETDEWEB)

    Wereszczak, Andrew A [ORNL; Fox, Ethan E [ORNL; Morrissey, Timothy G [ORNL; Vuono, Daniel J [ORNL

    2011-10-01

    This report summarizes TARDEC-sponsored work at Oak Ridge National Laboratory (ORNL) during the FY11 involving low velocity (< 30 m/s or < 65 mph) ball impact testing of Starphire soda lime silicate glass. The intent was to better understand low velocity impact response in the Starphire for sphere densities that bracketed that of rock. Five sphere materials were used: borosilicate glass, soda-lime silicate glass, steel, silicon nitride, and alumina. A gas gun was fabricated to produce controlled velocity delivery of the spheres against Starphire tile targets. Minimum impact velocities to initiate fracture in the Starphire were measured and interpreted in context to the kinetic energy of impact and the elastic property mismatch between the any of the five sphere-Starphire-target combinations. The primary observations from this low velocity (< 30 m/s or < 65 mph) testing were: (1) Frictional effects contribute to fracture initiation. (2) Spheres with a lower elastic modulus require less force to initiate fracture in the Starphire than spheres with a higher elastic modulus. (3) Contact-induced fracture did not initiate in the Starphire SLS for impact kinetic energies < 150 mJ. Fracture sometimes initiated or kinetic energies between {approx} 150-1100 mJ; however, it tended to occur when lower elastic modulus spheres were impacting it. Contact-induced fracture would always occur for impact energies > 1100 mJ. (4) The force necessary to initiate contact-induced fracture is higher under dynamic or impact conditions than it is under quasi-static indentation conditions. (5) Among the five used sphere materials, silicon nitride was the closest match to 'rock' in terms of both density and (probably) elastic modulus.

  9. Preparation of Nanocrystalline MoS2 Hollow Spheres

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Nanocrystalline MoS2 with hollow spherical morphology has been prepared by the hydrothermal method. The products are characterized by means of X-ray powder diffraction, transmission electron microscopy and high-resolution transmission electron microscopy. The experimental results give the evidence that the sample is consists of hollow spheres 400~600 nm in diameter, and there is much whisker on the surface of MoS2 hollow sphere.

  10. Existence of conformal metrics on spheres with prescribed Paneitz curvature

    CERN Document Server

    Ben-Ayed, M

    2003-01-01

    In this paper we study the problem of prescribing a fourth order conformal invariant (the Paneitz curvature) on the n-spheres, with n >= 5. Using tools from the theory of critical points at infinity, we provide some topological conditions on the level sets of a given function defined on the sphere, under which we prove the existence of conformal metric with prescribed Paneitz curvature.

  11. Semiclassical and quantum Liouville theory on the sphere

    OpenAIRE

    Menotti, Pietro; Vajente, Gabriele

    2004-01-01

    We solve the Riemann-Hilbert problem on the sphere topology for three singularities of finite strength and a fourth one infinitesimal, by determining perturbatively the Poincare' accessory parameters. In this way we compute the semiclassical four point vertex function with three finite charges and a fourth infinitesimal. Some of the results are extended to the case of n finite charges and m infinitesimal. With the same technique we compute the exact Green function on the sphere with three fin...

  12. Rigidity theorem forWillmore surfaces in a sphere

    Indian Academy of Sciences (India)

    Hongwei Xu; Dengyun Yang

    2016-05-01

    Let 2 be a compact Willmore surface in the (2 + )-dimensional unit sphere 2+. Denote by and the mean curvature and the squared length of the second fundamental form of 2, respectively. Set $\\rho^2 = S − 2H^2$. In this note, we proved that there exists a universal positive constant , such that if $\\parallel \\rho^2\\parallel_2 \\lt C$, then $\\rho^2 = 0$ and 2 is a totally umbilical sphere.

  13. Microwave characterization of submicrometer-sized nickel hollow sphere composites

    Science.gov (United States)

    Deng, Yida; Zhao, Ling; Shen, Bin; Liu, Lei; Hu, Wenbin

    2006-07-01

    In this work, we report on the microwave properties of the nickel hollow spheres (NHSs) synthesized by a facile autocatalytic reduction method. The resonance characterization of the NHS-polyvinyl butyral composite, due to the skin effect, is observed in the microwave frequency. It is shown that the resonant and the matching frequencies of the composite largely depend on the particle size of the spheres.

  14. The squashed fuzzy sphere, fuzzy strings and the Landau problem

    CERN Document Server

    Andronache, Stefan

    2015-01-01

    We discuss the squashed fuzzy sphere, which is a projection of the fuzzy sphere onto the equatorial plane, and use it to illustrate the stringy aspects of noncommutative field theory. We elaborate explicitly how strings linking its two coincident sheets arise in terms of fuzzy spherical harmonics. In the large N limit, the matrix-model Laplacian is shown to correctly reproduce the semi-classical dynamics of these charged strings, as given by the Landau problem.

  15. The squashed fuzzy sphere, fuzzy strings and the Landau problem

    Science.gov (United States)

    Andronache, Stefan; Steinacker, Harold C.

    2015-07-01

    We discuss the squashed fuzzy sphere, which is a projection of the fuzzy sphere onto the equatorial plane, and use it to illustrate the stringy aspects of noncommutative field theory. We elaborate explicitly how strings linking its two coincident sheets arise in terms of fuzzy spherical harmonics. In the large N limit, the matrix-model Laplacian is shown to correctly reproduce the semi-classical dynamics of these charged strings, as given by the Landau problem.

  16. Liouville theory and uniformization of four-punctured sphere

    CERN Document Server

    Hadasz, L; Hadasz, Leszek; Jaskolski, Zbigniew

    2006-01-01

    Few years ago Zamolodchikov and Zamolodchikov proposed an expression for the 4-point classical Liouville action in terms of the 3-point actions and the classical conformal block. In this paper we develop a method of calculating the uniformizing map and the uniformizing group from the classical Liouville action on n-punctured sphere and discuss the consequences of Zamolodchikovs conjecture for an explicit construction of the uniformizing map and the uniformizing group for the sphere with four punctures.

  17. Progress on sol-gel sphere-pac development

    Energy Technology Data Exchange (ETDEWEB)

    Suchomel, R R

    1978-01-01

    The ORNL sol-gel program is reviewed briefly. Advantages of the sol-gel sphere-pac are listed. Three sizes of microspheres are being used; the two largest sized fractions are blended and then loaded into the fuel rod, followed by packing of the smallest microspheres into void spaces using a low-energy vibrator. Sol-gel sphere-pac also appears attractive for breeder reactor fuel fabrication. (DLC)

  18. Sound Scattering and Its Reduction by a Janus Sphere Type

    Directory of Open Access Journals (Sweden)

    Deliya Kim

    2014-01-01

    Full Text Available Sound scattering by a Janus sphere type is considered. The sphere has two surface zones: a soft surface of zero acoustic impedance and a hard surface of infinite acoustic impedance. The zones are arranged such that axisymmetry of the sound field is preserved. The equivalent source method is used to compute the sound field. It is shown that, by varying the sizes of the soft and hard zones on the sphere, a significant reduction can be achieved in the scattered acoustic power and upstream directivity when the sphere is near a free surface and its soft zone faces the incoming wave and vice versa for a hard ground. In both cases the size of the sphere’s hard zone is much larger than that of its soft zone. The boundary location between the two zones coincides with the location of a zero pressure line of the incoming standing sound wave, thus masking the sphere within the sound field reflected by the free surface or the hard ground. The reduction in the scattered acoustic power diminishes when the sphere is placed in free space. Variations of the scattered acoustic power and directivity with the sound frequency are also given and discussed.

  19. Investigating hard sphere interactions through spin echo scattering angle measurement

    Science.gov (United States)

    Washington, Adam

    Spin Echo Scattering Angle Measurement (SESAME) allows neutron scattering instruments to perform real space measurements on large micron scale samples by encoding the scattering angle into the neutron's spin state via Larmor precession. I have built a SESAME instrument at the Low Energy Neutron Source. I have also assisted in the construction of a modular SESAME instrument on the ASTERIX beamline at Los Alamos National lab. The ability to tune these instruments has been proved mathematically and optimized and automated experimentally. Practical limits of the SESAME technique with respect to polarization analyzers, neutron spectra, Larmor elements, and data analysis were investigated. The SESAME technique was used to examine the interaction of hard spheres under depletion. Poly(methyl methacrylate) spheres suspended in decalin had previously been studied as a hard sphere solution. The interparticle correlations between the spheres were found to match the Percus-Yevick closure, as had been previously seen in dynamical light scattering experiments. To expand beyond pure hard spheres, 900kDa polystyrene was added to the solution in concentrations of less than 1% by mass. The steric effects of the polystyrene were expected to produce a short-range, attractive, "sticky" potential. Experiment showed, however, that the "sticky" potential was not a stable state and that the spheres would eventually form long range aggregates.

  20. Squeeze flow of a Carreau fluid during sphere impact

    KAUST Repository

    Uddin, J.

    2012-07-19

    We present results from a combined numerical and experimental investigation into the squeeze flow induced when a solid sphere impacts onto a thin, ultra-viscous film of non-Newtonian fluid. We examine both the sphere motion through the liquid as well as the fluid flow field in the region directly beneath the sphere during approach to a solid plate. In the experiments we use silicone oil as the model fluid, which is well-described by the Carreau model. We use high-speed imaging and particle tracking to achieve flow visualisation within the film itself and derive the corresponding velocity fields. We show that the radial velocity either diverges as the gap between the sphere and the wall diminishes (Z tip → 0) or that it reaches a maximum value and then decays rapidly to zero as the sphere comes to rest at a non-zero distance (Z tip = Z min ) away from the wall. The horizontal shear rate is calculated and is responsible for significant viscosity reduction during the approach of the sphere. Our model of this flow, based on lubrication theory, is solved numerically and compared to experimental trials. We show that our model is able to correctly describe the physical features of the flow observed in the experiments.

  1. Global Calibration of Multiple Cameras Based on Sphere Targets

    Directory of Open Access Journals (Sweden)

    Junhua Sun

    2016-01-01

    Full Text Available Global calibration methods for multi-camera system are critical to the accuracy of vision measurement. Proposed in this paper is such a method based on several groups of sphere targets and a precision auxiliary camera. Each camera to be calibrated observes a group of spheres (at least three, while the auxiliary camera observes all the spheres. The global calibration can be achieved after each camera reconstructs the sphere centers in its field of view. In the process of reconstructing a sphere center, a parameter equation is used to describe the sphere projection model. Theoretical analysis and computer simulation are carried out to analyze the factors that affect the calibration accuracy. Simulation results show that the parameter equation can largely improve the reconstruction accuracy. In the experiments, a two-camera system calibrated by our method is used to measure a distance about 578 mm, and the root mean squared error is within 0.14 mm. Furthermore, the experiments indicate that the method has simple operation and good flexibility, especially for the onsite multiple cameras without common field of view.

  2. The HERMES recoil detector

    Energy Technology Data Exchange (ETDEWEB)

    Airapetian, A. [Giessen Univ. (Germany). Physikalisches Inst.; Michigan Univ., Ann Arbor, MI (United States). Randall Laboratory of Physics; Aschenauer, E.C. [DESY, Zeuthen (Germany); Belostotski, S. [B.P. Konstantinov Petersburg Nuclear Physics Insitute, Gatchina (Russian Federation)] [and others; Collaboration: HERMES Recoil Detector Group

    2013-02-15

    For the final running period of HERA, a recoil detector was installed at the HERMES experiment to improve measurements of hard exclusive processes in charged-lepton nucleon scattering. Here, deeply virtual Compton scattering is of particular interest as this process provides constraints on generalised parton distributions that give access to the total angular momenta of quarks within the nucleon. The HERMES recoil detector was designed to improve the selection of exclusive events by a direct measurement of the four-momentum of the recoiling particle. It consisted of three components: two layers of double-sided silicon strip sensors inside the HERA beam vacuum, a two-barrel scintillating fibre tracker, and a photon detector. All sub-detectors were located inside a solenoidal magnetic field with an integrated field strength of 1Tm. The recoil detector was installed in late 2005. After the commissioning of all components was finished in September 2006, it operated stably until the end of data taking at HERA end of June 2007. The present paper gives a brief overview of the physics processes of interest and the general detector design. The recoil detector components, their calibration, the momentum reconstruction of charged particles, and the event selection are described in detail. The paper closes with a summary of the performance of the detection system.

  3. ATLAS Detector Interface Group

    CERN Multimedia

    Mapelli, L

    Originally organised as a sub-system in the DAQ/EF-1 Prototype Project, the Detector Interface Group (DIG) was an information exchange channel between the Detector systems and the Data Acquisition to provide critical detector information for prototype design and detector integration. After the reorganisation of the Trigger/DAQ Project and of Technical Coordination, the necessity to provide an adequate context for integration of detectors with the Trigger and DAQ lead to organisation of the DIG as one of the activities of Technical Coordination. Such an organisation emphasises the ATLAS wide coordination of the Trigger and DAQ exploitation aspects, which go beyond the domain of the Trigger/DAQ project itself. As part of Technical Coordination, the DIG provides the natural environment for the common work of Trigger/DAQ and detector experts. A DIG forum for a wide discussion of all the detector and Trigger/DAQ integration issues. A more restricted DIG group for the practical organisation and implementation o...

  4. Detectors for Tomorrow's Instruments

    Science.gov (United States)

    Moseley, Harvey

    2009-01-01

    Cryogenically cooled superconducting detectors have become essential tools for a wide range of measurement applications, ranging from quantum limited heterodyne detection in the millimeter range to direct searches for dark matter with superconducting phonon detectors operating at 20 mK. Superconducting detectors have several fundamental and practical advantages which have resulted in their rapid adoption by experimenters. Their excellent performance arises in part from reductions in noise resulting from their low operating temperatures, but unique superconducting properties provide a wide range of mechanisms for detection. For example, the steep dependence of resistance with temperature on the superconductor/normal transition provides a sensitive thermometer for calorimetric and bolometric applications. Parametric changes in the properties of superconducting resonators provides a mechanism for high sensitivity detection of submillimeter photons. From a practical point of view, the use of superconducting detectors has grown rapidly because many of these devices couple well to SQUID amplifiers, which are easily integrated with the detectors. These SQUID-based amplifiers and multiplexers have matured with the detectors; they are convenient to use, and have excellent noise performance. The first generation of fully integrated large scale superconducting detection systems are now being deployed. I will discuss the prospects for a new generation of instruments designed to take full advantage of the revolution in detector technology.

  5. Detectors - Electronics; Detecteurs - Electronique

    Energy Technology Data Exchange (ETDEWEB)

    Bregeault, J.; Gabriel, J.L.; Hierle, G.; Lebotlan, P.; Leconte, A.; Lelandais, J.; Mosrin, P.; Munsch, P.; Saur, H.; Tillier, J. [Lab. de Physique Corpusculaire, Caen Univ., 14 (France)

    1998-04-01

    The reports presents the main results obtained in the fields of radiation detectors and associated electronics. In the domain of X-ray gas detectors for the keV range efforts were undertaken to rise the detector efficiency. Multiple gap parallel plate chambers of different types as well as different types of X {yields} e{sup -} converters were tested to improve the efficiency (values of 2.4% at 60 KeV were reached). In the field of scintillators a study of new crystals has been carried out (among which Lutetium orthosilicate). CdTe diode strips for obtaining X-ray imaging were studied. The complete study of a linear array of 8 CdTe pixels has been performed and certified. The results are encouraging and point to this method as a satisfying solution. Also, a large dimension programmable chamber was used to study the influence of temperature on the inorganic scintillators in an interval from -40 deg. C to +150 deg. C. Temperature effects on other detectors and electronic circuits were also investigated. In the report mentioned is also the work carried out for the realization of the DEMON neutron multidetector. For neutron halo experiments different large area Si detectors associated with solid and gas position detectors were realized. In the frame of a contract with COGEMA a systematic study of Li doped glasses was undertaken aiming at replacing with a neutron probe the {sup 3}He counters presently utilized in pollution monitoring. An industrial prototype has been realised. Other studies were related to integrated analog chains, materials for Cherenkov detectors, scintillation probes for experiments on fundamental processes, gas position sensitive detectors, etc. In the field of associated electronics there are mentioned the works related to the multidetector INDRA, data acquisition, software gamma spectrometry, automatic gas pressure regulation in detectors, etc

  6. Hard-sphere limit of soft-sphere model for granular materials: stiffness dependence of steady granular flow.

    Science.gov (United States)

    Mitarai, Namiko; Nakanishi, Hiizu

    2003-02-01

    Dynamical behavior of steady granular flow is investigated numerically in the inelastic hard-sphere limit of the soft-sphere model. We find distinctively different limiting behaviors for the two flow regimes, i.e., the collisional flow and the frictional flow. In the collisional flow, the hard-sphere limit is straightforward; the number of collisions per particle per unit time converges to a finite value and the total contact time fraction with other particles goes to zero. For the frictional flow, however, we demonstrate that the collision rate diverges as the power of the particle stiffness so that the time fraction of the multiple contacts remains finite even in the hard-sphere limit, although the contact time fraction for the binary collisions tends to zero.

  7. ATLAS Inner Detector Alignment

    CERN Document Server

    Bocci, A

    2008-01-01

    The ATLAS experiment is a multi-purpose particle detector that will study high-energy particle collisions produced by the Large Hadron Collider at CERN. In order to achieve its physics goals, the ATLAS tracking requires that the positions of the silicon detector elements have to be known to a precision better than 10 μm. Several track-based alignment algorithms have been developed for the Inner Detector. An extensive validation has been performed with simulated events and real data coming from the ATLAS. Results from such validation are reported in this paper.

  8. Performance of GLD detector

    Indian Academy of Sciences (India)

    T Yoshioka

    2007-12-01

    Most of the important physics processes to be studied in the international linear collider (ILC) experiment have multi-jets in the final state. In order to achieve better jet energy resolution, the so-called particle flow algorithm (PFA) will be employed and there is a general consensus that PFA derives overall ILC detector design. Four detector concepts for the ILC experiment have been proposed so far in the world; the GLD detector that has a large inner calorimeter radius, which is considered to have an advantage for a PFA, is one of them. In this paper, general scheme and performance of the GLD-PFA will be presented.

  9. The Silicon Cube detector

    Energy Technology Data Exchange (ETDEWEB)

    Matea, I.; Adimi, N. [Centre d' Etudes Nucleaires de Bordeaux Gradignan - Universite Bordeaux 1 - UMR 5797, CNRS/IN2P3, Chemin du Solarium, BP 120, F-33175 Gradignan Cedex (France); Blank, B. [Centre d' Etudes Nucleaires de Bordeaux Gradignan - Universite Bordeaux 1 - UMR 5797, CNRS/IN2P3, Chemin du Solarium, BP 120, F-33175 Gradignan Cedex (France)], E-mail: blank@cenbg.in2p3.fr; Canchel, G.; Giovinazzo, J. [Centre d' Etudes Nucleaires de Bordeaux Gradignan - Universite Bordeaux 1 - UMR 5797, CNRS/IN2P3, Chemin du Solarium, BP 120, F-33175 Gradignan Cedex (France); Borge, M.J.G.; Dominguez-Reyes, R.; Tengblad, O. [Insto. Estructura de la Materia, CSIC, Serrano 113bis, E-28006 Madrid (Spain); Thomas, J.-C. [GANIL, CEA/DSM - CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5 (France)

    2009-08-21

    A new experimental device, the Silicon Cube detector, consisting of six double-sided silicon strip detectors placed in a compact geometry was developed at CENBG. Having a very good angular coverage and high granularity, it allows simultaneous measurements of energy and angular distributions of charged particles emitted from unbound nuclear states. In addition, large-volume Germanium detectors can be placed close to the collection point of the radioactive species to be studied. The setup is ideally suited for isotope separation on-line (ISOL)-type experiments to study multi-particle emitters and was tested during an experiment at the low-energy beam line of SPIRAL at GANIL.

  10. Microfluidic Scintillation Detectors

    CERN Multimedia

    Microfluidic scintillation detectors are devices of recent introduction for the detection of high energy particles, developed within the EP-DT group at CERN. Most of the interest for such technology comes from the use of liquid scintillators, which entails the possibility of changing the active material in the detector, leading to an increased radiation resistance. This feature, together with the high spatial resolution and low thickness deriving from the microfabrication techniques used to manufacture such devices, is desirable not only in instrumentation for high energy physics experiments but also in medical detectors such as beam monitors for hadron therapy.

  11. Effects of sphere size on the microstructure and mechanical properties of ductile iron-steel hollow sphere syntactic foams

    Institute of Scientific and Technical Information of China (English)

    Hamid Sazegaran; Ali-Reza Kiani-Rashid; Jalil Vahdati Khaki

    2016-01-01

    The effects of sphere size on the microstructural and mechanical properties of ductile iron–steel hollow sphere (DI–SHS) syntactic foamswere investigated in this study. The SHSs were manufactured by fluidized-bed coating via the Fe-based commercial powder–binder suspension onto expanded polystyrene spheres (EPSs). Afterwards, the DI–SHS syntactic foams were produced via a sand-mold casting process. The microstructures of specimens were investigated by optical microscopy, scanning electron microscopy (SEM), and en-ergy-dispersive X-ray spectroscopy (EDS). The microscopic evaluations of specimens reveal distinct regions composed of the DI matrix, SHS shells, and compatible interface. As a result, the microstructures and graphite morphologies of the DI matrix depend on sphere size. When the sphere size decreases, the area fractions of cementite and graphite phases are observed to increase and decrease, respectively. Compression tests were subsequently conducted at ambient temperature on the DI–SHS syntactic foams. The results reveal that the compres-sion behavior of the syntactic foams is enhanced with increasing sphere size. Furthermore, the compressed specimens demonstrate that mi-crocracks start and grow from the interface region.

  12. Effects of sphere size on the microstructure and mechanical properties of ductile iron-steel hollow sphere syntactic foams

    Science.gov (United States)

    Sazegaran, Hamid; Kiani-Rashid, Ali-Reza; Khaki, Jalil Vahdati

    2016-06-01

    The effects of sphere size on the microstructural and mechanical properties of ductile iron-steel hollow sphere (DI-SHS) syntactic foams were investigated in this study. The SHSs were manufactured by fluidized-bed coating via the Fe-based commercial powder-binder suspension onto expanded polystyrene spheres (EPSs). Afterwards, the DI-SHS syntactic foams were produced via a sand-mold casting process. The microstructures of specimens were investigated by optical microscopy, scanning electron microscopy (SEM), and energy- dispersive X-ray spectroscopy (EDS). The microscopic evaluations of specimens reveal distinct regions composed of the DI matrix, SHS shells, and compatible interface. As a result, the microstructures and graphite morphologies of the DI matrix depend on sphere size. When the sphere size decreases, the area fractions of cementite and graphite phases are observed to increase and decrease, respectively. Compression tests were subsequently conducted at ambient temperature on the DI-SHS syntactic foams. The results reveal that the compression behavior of the syntactic foams is enhanced with increasing sphere size. Furthermore, the compressed specimens demonstrate that microcracks start and grow from the interface region.

  13. Novel Photo-Detectors and Photo-Detector Systems

    OpenAIRE

    Danilov, M.

    2008-01-01

    Recent developments in photo-detectors and photo-detector systems are reviewed. The main emphasis is made on Silicon Photo-Multipliers (SiPM) - novel and very attractive photo-detectors. Their main features are described. Properties of detectors manufactured by different producers are compared. Different applications are discussed including calorimeters, muon detection, tracking, Cherenkov light detection, and time of flight measurements.

  14. Pocked surface neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, Douglas (Whitmore Lake, MI); Klann, Raymond (Bolingbrook, IL)

    2003-04-08

    The detection efficiency, or sensitivity, of a neutron detector material such as of Si, SiC, amorphous Si, GaAs, or diamond is substantially increased by forming one or more cavities, or holes, in its surface. A neutron reactive material such as of elemental, or any compound of, .sup.10 B, .sup.6 Li, .sup.6 LiF, U, or Gd is deposited on the surface of the detector material so as to be disposed within the cavities therein. The portions of the neutron reactive material extending into the detector material substantially increase the probability of an energetic neutron reaction product in the form of a charged particle being directed into and detected by the neutron detector material.

  15. Europe plans megaton detector

    CERN Multimedia

    Cartlidge, Edwin

    2004-01-01

    A group of French and Italian particle physicists hopes to carry on the long tradition of building large underground detectors by constructing a device deep under the Alps containing a million tonnes of extremely pure water.

  16. OPAL detector electromagnetic calorimeter

    CERN Multimedia

    1988-01-01

    Half of the electromagnetic calorimeter of the OPAL detector is seen in this photo. This calorimeter consists of 4720 blocks of lead glass. It was used to detect and measure the energy of photons, electrons and positrons by absorbing them.

  17. The CLIC Detector Concept

    CERN Document Server

    Pitters, Florian Michael

    2016-01-01

    CLIC is a concept for a future linear collider that would provide e+e- collisions at up to 3 TeV. The physics aims require a detector system with excellent jet energy and track momentum resolution, highly efficient flavour-tagging and lepton identification capabilities, full geometrical coverage extending to low polar angles and timing information in the order of nanoseconds to reject beam-induced background. To deal with those requirements, an extensive R&D programme is in place to overcome current technological limits. The CLIC detector concept includes a low-mass all-silicon vertex and tracking detector system and fine-grained calorimeters designed for particle flow analysis techniques, surrounded by a 4 T solenoid magnet. An overview of the requirements and design optimisations for the CLIC detector concept is presented.

  18. The LUX Prototype Detector

    CERN Document Server

    Akerib, D S; Bedikian, S; Bernstein, A; Bolozdynya, A; Bradley, A; Cahn, S; Carr, D; Chapman, J J; Clark, K; Classen, T; Curioni, A; Dahl, C E; Dazeley, S; deViveiros, L; Dragowsky, M; Druszkiewicz, E; Fiorucci, S; Gaitskell, R J; Hall, C; Faham, C; Holbrook, B; Kastens, L; Kazkaz, K; Kwong, J; Lander, R; Leonard, D; Malling, D; Mannino, R; McKinsey, D N; Mei, D; Mock, J; Morii, M; Nikkel, J; Phelps, P; Shutt, T; Skulski, W; Sorensen, P; Spaans, J; Steigler, T; Svoboda, R; Sweany, M; Thomson, J; Tripathi, M; Walsh, N; Webb, R; White, J; Wolfs, F L H; Woods, M; Zhang, C

    2012-01-01

    The LUX (Large Underground Xenon) detector is a two-phase xenon Time Projection Chamber (TPC) designed to search for WIMP-nucleon dark matter interactions. As with all noble element detectors, continuous purification of the detector medium is essential to produce a large ($>$1ms) electron lifetime; this is necessary for efficient measurement of the electron signal which in turn is essential for achieving robust discrimination of signal from background events. In this paper we describe the development of a novel purification system deployed in a prototype detector. The results from the operation of this prototype indicated heat exchange with an efficiency above 94% up to a flow rate of 42 slpm, allowing for an electron drift length greater than 1 meter to be achieved in approximately two days and sustained for the duration of the testing period.

  19. The pixelated detector

    CERN Multimedia

    Sutton, C

    1990-01-01

    "Collecting data as patterns of light or subatomic particles is vitally important in all the sciences. The new generation of solid-state detectors called pixel devices could transform experimental research at all levels" (4 pages).

  20. GRAVITY detector systems

    Science.gov (United States)

    Mehrgan, Leander H.; Finger, Gert; Eisenhauer, Frank; Panduro, Johana

    2016-08-01

    GRAVITY is a second generation instrument for the VLT Interferometer, designed for high-precision narrow-angle astrometry and phase-referenced interferometric imaging in the K-band. It will combine the AO corrected beams of the four VLT telescopes. In total, the GRAVITY instrument uses five eAPD detectors four for the infrared wavefront sensors of each telescope and one for the fringe tracker. In addition two Hawaii2RG arrays are installed, one for the acquisition camera and one for the spectrometer. The SAPHIRA eAPD array is a newly developed near-infrared detector with sub-electron noise performance at frame rates > 1Kfps. For all seven detectors the ESO common controller, NGC, is used. This paper presents an overview and comparison of GRAVITY detector systems and their final performances at the telescope

  1. Hybrid photon detectors

    CERN Document Server

    D'Ambrosio, C

    2003-01-01

    Hybrid photon detectors detect light via vacuum photocathodes and accelerate the emitted photoelectrons by an electric field towards inversely polarized silicon anodes, where they are absorbed, thus producing electron-hole pairs. These, in turn, are collected and generate electronic signals on their ohmic contacts. This review first describes the characteristic properties of the main components of hybrid photon detectors: light entrance windows, photocathodes, and silicon anodes. Then, essential relations describing the trajectories of photoelectrons in electric and magnetic fields and their backscattering from the silicon anodes are derived. Depending on their anode configurations, three families of hybrid photon detectors are presented: hybrid photomultiplier tubes with single anodes for photon counting with high sensitivity and for gamma spectroscopy; multi-anode photon detector tubes with anodes subdivided into square or hexagonal pads for position-sensitive photon detection; imaging silicon pixel array t...

  2. Infrared Detectors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The end goal of this project is to develop proof-of-concept infrared detectors which can be integrated in future infrared instruments engaged in remote...

  3. ALICE Forward Multiplicity Detector

    CERN Multimedia

    Christensen, C

    2013-01-01

    The Forward Multiplicity Detector (FMD) extends the coverage for multiplicity of charge particles into the forward regions - giving ALICE the widest coverage of the 4 LHC experiments for these measurements.

  4. Improved CO [lidar detector

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, P.L.; Busch, G.E.; Thompson, D.C.; Remelius, D.K.; Wells, F.D.

    1999-07-18

    A high sensitivity, CO{sub 2} lidar detector, based on recent advances in ultra-low noise, readout integrated circuits (ROIC), is being developed. This detector will combine a high speed, low noise focal plane array (FPA) with a dispersive grating spectrometer. The spectrometer will filter the large background flux, thereby reducing the limiting background photon shot noise. In order to achieve the desired low noise levels, the HgCdTe FPA will be cooled to {approximately}50K. High speed, short pulse operation of the lidar system should enable the detector to operate with the order of a few noise electrons in the combined detector/ ROIC output. Current receiver design concepts will be presented, along with their expected noise performance.

  5. Fiber optic detector

    Energy Technology Data Exchange (ETDEWEB)

    Partin, J.K.; Ward, T.E.; Grey, A.E.

    1990-12-31

    This invention is comprised of a portable fiber optic detector that senses the presence of specific target chemicals by exchanging the target chemical for a fluorescently-tagged antigen that is bound to an antibody which is in turn attached to an optical fiber. Replacing the fluorescently-tagged antigen reduces the fluorescence so that a photon sensing detector records the reduced light level and activates an appropriate alarm or indicator.

  6. Phi factory detector requirements

    Energy Technology Data Exchange (ETDEWEB)

    Arisaka, K.; Atac, M.; Berg, R.; Buchanan, C.; Calvette, M.; Khazin, B.; Kinoshita, K.; Muller, T.; Ohshima, T.; Olsen, S.; Park, J.; Santoni, C.; Shirai, J.; Solodov, E.; Thompson, J.; Triggiani, G.; Ueno, K.; Yamamoto, H.; Detector and Simulation Working Group

    1991-08-01

    We identify the experimental problems and the conditions required for successful phi-factory operation, and show the range of detector parameters which, in conjunction with different machine designs, may meet these conditions. We started by considering, comparing and criticizing the Italian and Novosibirsk designs. With this discussion as a background, we defined the apparent experimental problems and detector constraints. In this article we summarize our understanding. (orig./HSI).

  7. Detector Control System for the ATLAS Forward Proton detector

    CERN Document Server

    Czekierda, Sabina; The ATLAS collaboration

    2017-01-01

    The ATLAS Forward Proton (AFP) is a forward detector using a Roman Pot technique, recently installed in the LHC tunnel. It is aiming at registering protons that were diffractively or electromagnetically scattered in soft and hard processes. Infrastructure of the detector consists of hardware placed both in the tunnel and in the control room USA15 (about 330 meters from the Roman Pots). AFP detector, like the other detectors of the ATLAS experiment, uses the Detector Control System (DCS) to supervise the detector and to ensure its safe and coherent operation, since the incorrect detector performance may influence the physics results. The DCS continuously monitors the detector parameters, subset of which is stored in data bases. Crucial parameters are guarded by alarm system. A detector representation as a hierarchical tree-like structure of well-defined subsystems built with the use of the Finite State Machine (FSM) toolkit allows for overall detector operation and visualization. Every node in the hierarchy is...

  8. Tin-wall hollow ceramic spheres from slurries. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, A.T.; Cochran, J.K.

    1992-12-31

    The overall objective of this effort was to develop a process for economically fabricating thin-wall hollow ceramic spheres from conventional ceramic powders using dispersions. This process resulted in successful production of monosized spheres in the mm size range which were point contact bonded into foams. Thin-wall hollow ceramic spheres of small (one to five millimeter) diameter have novel applications as high-temperature insulation and light structural materials when bonded into monolithic foams. During Phase 1 of this program the objective as to develop a process for fabricating thin-wall hollow spheres from powder slurries using the coaxial nozzle fabrication method. Based on the success during Phase 1, Phase 2 was revised to emphasize the assessment of the potential structural and insulation applications for the spheres and modeling of the sphere formation process was initiated. As more understanding developed, it was clear that to achieve successful structural application, the spheres had to be bonded into monolithic foams and the effort was further expanded to include both bonding into structures and finite element mechanical modeling which became the basis of Phase 3. Successful bonding techniques and mechanical modeling resulted but thermal conductivities were higher than desired for insulating activities. In addition, considerable interest had been express by industry for the technology. Thus the final Phase 4 concentrated on methods to reduce thermal conductivity by a variety of techniques and technology transfer through individualized visits. This program resulted in three Ph.D. theses and 10 M.S. theses and they are listed in the appropriate technical sections.

  9. Characterization of maximally random jammed sphere packings: Voronoi correlation functions.

    Science.gov (United States)

    Klatt, Michael A; Torquato, Salvatore

    2014-11-01

    We characterize the structure of maximally random jammed (MRJ) sphere packings by computing the Minkowski functionals (volume, surface area, and integrated mean curvature) of their associated Voronoi cells. The probability distribution functions of these functionals of Voronoi cells in MRJ sphere packings are qualitatively similar to those of an equilibrium hard-sphere liquid and partly even to the uncorrelated Poisson point process, implying that such local statistics are relatively structurally insensitive. This is not surprising because the Minkowski functionals of a single Voronoi cell incorporate only local information and are insensitive to global structural information. To improve upon this, we introduce descriptors that incorporate nonlocal information via the correlation functions of the Minkowski functionals of two cells at a given distance as well as certain cell-cell probability density functions. We evaluate these higher-order functions for our MRJ packings as well as equilibrium hard spheres and the Poisson point process. It is shown that these Minkowski correlation and density functions contain visibly more information than the corresponding standard pair-correlation functions. We find strong anticorrelations in the Voronoi volumes for the hyperuniform MRJ packings, consistent with previous findings for other pair correlations [A. Donev et al., Phys. Rev. Lett. 95, 090604 (2005)PRLTAO0031-900710.1103/PhysRevLett.95.090604], indicating that large-scale volume fluctuations are suppressed by accompanying large Voronoi cells with small cells, and vice versa. In contrast to the aforementioned local Voronoi statistics, the correlation functions of the Voronoi cells qualitatively distinguish the structure of MRJ sphere packings (prototypical glasses) from that of not only the Poisson point process but also the correlated equilibrium hard-sphere liquids. Moreover, while we did not find any perfect icosahedra (the locally densest possible structure in which a

  10. Modelling semiconductor pixel detectors

    CERN Document Server

    Mathieson, K

    2001-01-01

    expected after 200 ps in most cases. The effect of reducing the charge carrier lifetime and examining the charge collection efficiency has been utilised to explore how these detectors would respond in a harsh radiation environment. It is predicted that over critical carrier lifetimes (10 ps to 0.1 ns) an improvement of 40 % over conventional detectors can be expected. This also has positive implications for fabricating detectors, in this geometry, from materials which might otherwise be considered substandard. An analysis of charge transport in CdZnTe pixel detectors has been performed. The analysis starts with simulation studies into the formation of contacts and their influence on the internal electric field of planar detectors. The models include a number of well known defect states and these are balanced to give an agreement with a typical experimental I-V curve. The charge transport study extends to the development of a method for studying the effect of charge sharing in highly pixellated detectors. The ...

  11. Gamma ray detector modules

    Science.gov (United States)

    Capote, M. Albert (Inventor); Lenos, Howard A. (Inventor)

    2009-01-01

    A radiation detector assembly has a semiconductor detector array substrate of CdZnTe or CdTe, having a plurality of detector cell pads on a first surface thereof, the pads having a contact metallization and a solder barrier metallization. An interposer card has planar dimensions no larger than planar dimensions of the semiconductor detector array substrate, a plurality of interconnect pads on a first surface thereof, at least one readout semiconductor chip and at least one connector on a second surface thereof, each having planar dimensions no larger than the planar dimensions of the interposer card. Solder columns extend from contacts on the interposer first surface to the plurality of pads on the semiconductor detector array substrate first surface, the solder columns having at least one solder having a melting point or liquidus less than 120 degrees C. An encapsulant is disposed between the interposer circuit card first surface and the semiconductor detector array substrate first surface, encapsulating the solder columns, the encapsulant curing at a temperature no greater than 120 degrees C.

  12. ATLAS Inner Detector (Pixel Detector and Silicon Tracker)

    CERN Multimedia

    ATLAS Outreach

    2006-01-01

    To raise awareness of the basic functions of the Pixel Detector and Silicon Tracker in the ATLAS detector on the LHC at CERN. This colorful 3D animation is an excerpt from the film "ATLAS-Episode II, The Particles Strike Back." Shot with a bug's eye view of the inside of the detector. The viewer is taken on a tour of the inner workings of the detector, seeing critical pieces of the detector and hearing short explanations of how each works.

  13. Detectors on the drawing board

    CERN Multimedia

    Katarina Anthony

    2011-01-01

    Linear collider detector developers inside and outside CERN are tackling the next generation of detector technology. While their focus has centred on high-energy linear collider detectors, their innovative concepts and designs will be applicable to any future detector.   A simulated event display in one of the new generation detectors. “While the LHC experiments remain the pinnacle of detector technology, you may be surprised to realise that the design and expertise behind them is well over 10 years old,” says Lucie Linssen, CERN’s Linear Collider Detector (LCD) project manager whose group is pushing the envelope of detector design. “The next generation of detectors will have to surpass the achievements of the LHC experiments. It’s not an easy task but, by observing detectors currently in operation and exploiting a decade’s worth of technological advancements, we’ve made meaningful progress.” The LCD team is curr...

  14. Evaluation of Delayed Critical ORNL Unreflected HEU Metal Sphere (ORSphere)

    Science.gov (United States)

    Marshall, M. A.; Bess, J. D.

    2014-04-01

    In 1971 and 1972 experimenters at the Oak Ridge Critical Experiment Facility performed critical experiments using an unreflected metal sphere of highly enriched uranium (HEU). The sphere used for the criticality experiments, originally used for neutron leakage spectrum measurements by General Atomic Company, consisted of three main parts and were assembled with a vertical assembly machine. Two configurations were tested. The first was nearly spherical with a nominal radius of 3.467 inches and had a reactivity of 68.1 ± 2.0 cents. The sphere parts were then re-machined as a sphere with a nominal radius of 3.4425 inches. This assembly had a reactivity of -23 cents. The method, dimensions, and uncertainty of the critical experiment were extensively recorded and documented. The original purpose of the experiments was for comparison to GODIVA I experiments. The ORNL unreflected HEU Metal Spheres have been evaluated for inclusion in the International Handbook of Evaluated Criticality Safety Benchmark Experiments (scheduled for inclusion in the September 2013 edition).

  15. Crown sealing and buckling instability during water entry of spheres

    KAUST Repository

    Marston, J. O.

    2016-04-05

    We present new observations from an experimental investigation of the classical problem of the crown splash and sealing phenomena observed during the impact of spheres onto quiescent liquid pools. In the experiments, a 6 m tall vacuum chamber was used to provide the required ambient conditions from atmospheric pressure down to of an atmosphere, whilst high-speed videography was exploited to focus primarily on the above-surface crown formation and ensuing dynamics, paying particular attention to the moments just prior to the surface seal. In doing so, we have observed a buckling-type azimuthal instability of the crown. This instability is characterised by vertical striations along the crown, between which thin films form that are more susceptible to the air flow and thus are drawn into the closing cavity, where they atomize to form a fine spray within the cavity. To elucidate to the primary mechanisms and forces at play, we varied the sphere diameter, liquid properties and ambient pressure. Furthermore, a comparison between the entry of room-temperature spheres, where the contact line pins around the equator, and Leidenfrost spheres (i.e. an immersed superheated sphere encompassed by a vapour layer), where there is no contact line, indicates that the buckling instability appears in all crown sealing events, but is intensified by the presence of a pinned contact line. © 2016 Cambridge University Press.

  16. Convenient integrating sphere scanner for accurate luminous flux measurements

    Science.gov (United States)

    Winter, S.; Lindemann, M.; Jordan, W.; Binder, U.; Anokhin, M.

    2009-08-01

    Measurement results and applications of a recently developed device for the measurement of the spatial uniformity of integrating spheres are presented. Due to the complexity of their implementation, sphere scanners are mainly used by national metrology institutes to increase the accuracy of relative and absolute luminous flux measurements (Ohno et al 1997 J. IES 26 107-14, Ohno and Daubach 2001 J. IES 30 105-15, Ohno 1998 Metrologia 35 473-8, Hovila et al 2004 Metrologia 41 407-13). The major drawback of traditional scanners for integrating spheres is the necessity of a complex and time-consuming sphere modification, as the lamp holder has to be replaced by a new scanner holder with additional cables for power supply and for communication with the stepping motor control unit (Ohno et al 1997 J. IES 26 107-14). Therefore, with traditional scanners the relative spatial sphere responsivity already changes due to the installation of a special scanner holder. The new scanner simply substitutes the lamp under test: it can be screwed into an E27 lamp socket, as it needs only two electrical contacts. Two wires are simultaneously used for the power supply of the stepping motor control unit, the scanner light source (LED) and for the signal transmission of commands and results. The benefits of scanner-assisted measurements are shown for spotlight lamp calibrations.

  17. Hydrothermal Syntheses of Colloidal Carbon Spheres from Cyclodextrins

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Yongsoon; Wang, Li Q.; Bae, In-Tae; Arey, Bruce W.; Exarhos, Gregory J.

    2008-09-18

    Colloidal carbon spheres have been prepared from aqueous alpha-, beta-, and gamma-cyclodextrin (CD) solutions in closed systems under hydrothermal conditions at 160 oC. Both liquid and solid-state 13C NMR spectra taken for samples at different reaction times have been used to monitor the dehydration and carbonization pathways. CD slowly hydrolyzes to glucose and forms 5-hydroxymethyl furfural (HMF) followed by carbonization into colloidal carbon spheres. The isolated carbon spheres are 70-150 nm in diameter, exhibit a core-shell structure, and are comprised of a condensed core (C=C) peppered with resident chemical functionalities including carboxylate and hydroxyl groups. Evidence from 13C solid-state NMR and FT-IR spectra reveal that the evolving carbon spheres show a gradual increase in the amount of aromatic carbon as a function of reaction time and that the carbon spheres generated from gamma-CD contain significantly higher aromatic carbon than those derived from alpha- and beta-CD.

  18. Experimental determination of the dynamics of an acoustically levitated sphere

    Energy Technology Data Exchange (ETDEWEB)

    Pérez, Nicolás, E-mail: nico@fisica.edu.uy [Centro Universitario de Paysandú, Universidad de la República, Paysandú (Uruguay); Andrade, Marco A. B. [Institute of Physics, University of São Paulo, São Paulo (Brazil); Canetti, Rafael [Facultad de Ingeniería, Universidad de la República, Montevideo (Uruguay); Adamowski, Julio C. [Department of Mechatronics and Mechanical Systems Engineering, Escola Politécnica, University of São Paulo, São Paulo (Brazil)

    2014-11-14

    Levitation of solids and liquids by ultrasonic standing waves is a promising technique to manipulate materials without contact. When a small particle is introduced in certain areas of a standing wave field, the acoustic radiation force pushes the particle to the pressure node. This movement is followed by oscillations of the levitated particle. Aiming to investigate the particle oscillations in acoustic levitation, this paper presents the experimental and numerical characterization of the dynamic behavior of a levitated sphere. To obtain the experimental response, a small sphere is lifted by the acoustic radiation force. After the sphere lift, it presents a damped oscillatory behavior, which is recorded by a high speed camera. To model this behavior, a mass-spring-damper system is proposed. In this model, the acoustic radiation force that acts on the sphere is theoretically predicted by the Gor'kov theory and the viscous forces are modeled by two damping terms, one term proportional to the square of the velocity and another term proportional to the particle velocity. The proposed model was experimentally verified by using different values of sound pressure amplitude. The comparison between numerical and experimental results shows that the model can accurately describe the oscillatory behavior of the sphere in an acoustic levitator.

  19. Realistic packed bed generation using small numbers of spheres

    Energy Technology Data Exchange (ETDEWEB)

    Pavlidis, D., E-mail: dimitrios.pavlidis04@imperial.ac.uk; Lathouwers, D.

    2013-10-15

    Highlights: • A method for generating 3D, periodic, closely packed beds of small numbers (<50) of spheres is presented. • The method is able to reproduce characteristics for the entirety (including nearwall area) of a randomly stacked bed. • Results are in good agreement with reference numerical data. -- Abstract: A method for stochastically generating three-dimensional, periodic, closely packed beds of small numbers (less than 50) of spheres is presented. This is an essential and integral part of realistic modelling of fluid flow and heat transfer through packed beds. In order to be able to reproduce the entirety of these complex geometries (in the radial direction) using small numbers of spheres, they are divided into two regions: the near-wall region (up to 4–5 sphere diameters from the solid wall in the wall-normal direction) and the core region. Near-wall stackings are doubly periodic and include a solid wall, while core stackings are triply periodic. A computational method for generating such geometries is presented for each region. Both are based on overlap removal methods. Results are compared against reference numerical data. Diagnostics used to evaluate the models include average packing fractions and coordination numbers, porosity profiles and distributions of the angle between two spheres which touch a common neighbour. Results are in good qualitative and quantitative agreement with the available reference data.

  20. ORSPHERE: CRITICAL, BARE, HEU(93.2)-METAL SPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Margaret A. Marshall

    2013-09-01

    In the early 1970’s Dr. John T. Mihalczo (team leader), J.J. Lynn, and J.R. Taylor performed experiments at the Oak Ridge Critical Experiments Facility (ORCEF) with highly enriched uranium (HEU) metal (called Oak Ridge Alloy or ORALLOY) in an attempt to recreate GODIVA I results with greater accuracy than those performed at Los Alamos National Laboratory in the 1950’s (HEU-MET-FAST-001). The purpose of the Oak Ridge ORALLOY Sphere (ORSphere) experiments was to estimate the unreflected and unmoderated critical mass of an idealized sphere of uranium metal corrected to a density, purity, and enrichment such that it could be compared with the GODIVA I experiments. “The very accurate description of this sphere, as assembled, establishes it as an ideal benchmark for calculational methods and cross-section data files.” (Reference 1) While performing the ORSphere experiments care was taken to accurately document component dimensions (±0. 0001 in. for non-spherical parts), masses (±0.01 g), and material data The experiment was also set up to minimize the amount of structural material in the sphere proximity. A three part sphere was initially assembled with an average radius of 3.4665 in. and was then machined down to an average radius of 3.4420 in. (3.4425 in. nominal). These two spherical configurations were evaluated and judged to be acceptable benchmark experiments; however, the two experiments are highly correlated.

  1. Evaluation of the sphere anemometer for atmospheric wind measurements

    Science.gov (United States)

    Heisselmann, Hendrik; Peinke, Joachim; Hoelling, Michael

    2014-11-01

    Our contribution will compare the sphere anemometer and two standard sensors for wind energy and meteorology based on data from a near-shore measurement campaign. We will introduce the characteristics of the sphere anemometer - a drag-based sensor for simultaneous wind speed and direction measurements, which makes use of the highly resolving light pointer principle to detect the velocity-dependent deflection of sphere mounted on a flexible tube. Sphere anemometer, cup anemometer and 3D sonic anemometer were installed at near-shore site in the German Wadden Sea. A comparison of the anemometers was carried out based on several month of high frequency data obtained from this campaign. The measured wind speed and direction data were analyzed to evaluate the capability of the sphere anemometer under real operating conditions, while the sensor characteristics obtained from previous wind tunnel experiments under turbulent conditions served as a reference to assess the durability and to identify challenges of the new anemometer. A characterization of the atmospheric wind conditions at the test site is performed based on the recorded wind data. Wind speed and wind direction averages and turbulence intensities are analyzed as well as power spectra and probability density functions. Supported by the German Ministry of Economics and Energy.

  2. Development of a system for passive spectrometry characterization neutron of a cyclotron; Desarrollo de un sistema de espectrometria pasivo para la caracterizacion neutronica de un ciclotron

    Energy Technology Data Exchange (ETDEWEB)

    Mendez, R.; Guerrero, J. E.; Lagares, J. I.; Sansaloni, F.; Perez, J. M.; Llop, J.; Kralik, M.

    2013-07-01

    The most widely used for Neutron spectrometry system is formed by the Bonner spheres with an active sensor sensitive to thermal neutrons in its Center. But, the presence of strong electromagnetic fields and the hold character around a cyclotron radiation detectors active employment make unviable so it is necessary to replace it with other liabilities. In this case it has resorted to the use of Au foils such as thermal neutron detectors, found the matrix the new spectrometer response and has been validated with a source of {sup 2}52Cf for later measurements in the interior of the bunker of a cyclotron production of radioisotopes for PET. (Author)

  3. VMware vSphere 5 Administration Instant Reference

    CERN Document Server

    Kusek, Christopher; Daniel, Andy

    2011-01-01

    Compact and portable reference guide for quick answers to VMware vSphere If you're looking to migrate to the newest version of VMware vSphere, this concise guide will get you up to speed and down to business in no time. If you're new to VMware vSphere, this book is for you too! The compact size of this quick reference makes it easy for you to have by your side—whether you're in the field, server room, or at your desk. Helpful elements for finding information such as thumb tabs, tables of contents with page numbers at the beginning of each chapter, and special headers puts what you need a

  4. Damped Arrow-Hurwicz algorithm for sphere packing

    Science.gov (United States)

    Degond, Pierre; Ferreira, Marina A.; Motsch, Sebastien

    2017-03-01

    We consider algorithms that, from an arbitrarily sampling of N spheres (possibly overlapping), find a close packed configuration without overlapping. These problems can be formulated as minimization problems with non-convex constraints. For such packing problems, we observe that the classical iterative Arrow-Hurwicz algorithm does not converge. We derive a novel algorithm from a multi-step variant of the Arrow-Hurwicz scheme with damping. We compare this algorithm with classical algorithms belonging to the class of linearly constrained Lagrangian methods and show that it performs better. We provide an analysis of the convergence of these algorithms in the simple case of two spheres in one spatial dimension. Finally, we investigate the behaviour of our algorithm when the number of spheres is large in two and three spatial dimensions.

  5. The Schr\\"odinger-Poisson system on the sphere

    CERN Document Server

    Gérard, Patrick

    2010-01-01

    We study the Schr\\"odinger-Poisson system on the unit sphere $\\SS^2$ of $\\RR^3$, modeling the quantum transport of charged particles confined on a sphere by an external potential. Our first results concern the Cauchy problem for this system. We prove that this problem is regularly well-posed on every $H^s(\\SS ^2)$ with $s>0$, and not uniformly well-posed on $L^2(\\SS ^2)$. The proof of well-posedness relies on multilinear Strichartz estimates, the proof of ill-posedness relies on the construction of a counterexample which concentrates exponentially on a closed geodesic. In a second part of the paper, we prove that this model can be obtained as the limit of the three dimensional Schr\\"odinger-Poisson system, singularly perturbed by an external potential that confines the particles in the vicinity of the sphere.

  6. Improved List Sphere Decoder for Multiple Antenna Systems

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    An improved list sphere decoder (ILSD) is proposed based on the conventional list sphere decoder (LSD) and the reduced-complexity maximum likelihood sphere-decoding algorithm. Unlike the conventional LSD with fixed initial radius, the ILSD adopts an adaptive radius to accelerate the list construction. Characterized by low-complexity and radius-insensitivity, the proposed algorithm makes iterative joint detection and decoding more realizable in multiple-antenna systems. Simulation results show that computational savings of ILSD over LSD are more apparent with more transmit antennas or larger constellations, and with no performance degradation. Because the complexity of the ILSD algorithm almost keeps invariant with the increasing of initial radius, the BER performance can be improved by selecting a sufficiently large radius.

  7. AXISYMMETRIC FLOW THROUGH A PERMEABLE NEAR-SPHERE

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    An analytical approach is described for the axisymmetric flow through a permeable near-sphere with a modification to boundary conditions in order to account permeability. The Stokes equation was solved by a regular perturbation technique up to the second order correction in epsilon representing the deviation from the radius of nondeformed sphere. The drag and the flow rate were calculated and the results were evaluated from the point of geometry and the permeability of the surface. An attempt also was made to apply the theory to the filter feeding problem. The filter appendages of small ecologically important aquatic organisms were modeled as axisymmetric permeable bodies, therefore a rough model for this problem was considered here as an oblate spheroid or near-sphere.

  8. Diversity and the European Public Sphere. The Case of Denmark

    DEFF Research Database (Denmark)

    Pristed Nielsen, Helene; Siim, Birte; Agustin, Lise Rolandsen

    2010-01-01

    This report contains empirical findings from the Danish case within the Eurosphere project. It is based on 55 interviews with Danish opinion makers on the topics of diversity, EU polity and the European public sphere The empirical research programme of EUROSPHERE aims to explore whether...... it is possible to develop an inclusive public sphere in the European Union. Based on different scenarios and alternative combinations of different approaches to diversity, polity, and the public sphere, EUROSPHERE aims to identify the notions, discourses, and objectives that are in the process of becoming...... Series represents the finalization of the very first step of a comprehensive comparative research programme. The aim of this series is to provide a brief summary of a huge data material collected by the project researchers. This report summarises empirical findings from the Danish setting...

  9. Anomalous Motion of a Sphere Falling through Water

    Science.gov (United States)

    Kuwabara, Goro; Chiba, Seiji; Kono, Kimitoshi

    1983-10-01

    A pendulum motion of a sphere falling through water under the action of gravity was studied experimentally for the Reynolds number between 1.5× 103 and 4.0× 104, and its explanation is given. The quantitative analysis of the path with stereoscopic photographs showed that the bending of the path from the vertical line occured through the action of a side force L acting perpendicularly to the path and alternating its direction with a frequency whose Strouhal number was about 0.2. Visual observation with a VIDEO revealed that the force L arose from a circulating flow around the sphere, which was generated and alternated its sense of rotation by shedding asymmetric vortex loops from alternate sides of the sphere. The lift coefficient was found to be about 0.3. The drag coefficient increased from 0.4 to 0.9 when the circulating flow reversed.

  10. Radiation of charge bunches revolving around a metamaterial sphere

    Science.gov (United States)

    Torabi, Mahmoud; Shokri, Babak

    2017-01-01

    We investigate the interaction of a relativistic uniformly rotating charge with a metamaterial sphere in the microwave range. The charge revolves around the sphere at the equatorial plane. The root mean square of the radiation field for different types of metamaterial spheres is presented and its dependence on some usual parameters is considered. They demonstrate that the radiation field is concentrated near the surface and shifts towards the centre by increasing charge energy for conventional and double-negative metamaterials. The stopping and deflection forces acting on the charge are also calculated. Finally, we generalize these results to a line charge bunch. This study has potential application in the area of high-power radiation sources and accelerators.

  11. Detectors in Extreme Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Blaj, G. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Carini, G. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Carron, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Haller, G. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hart, P. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hasi, J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Herrmann, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Kenney, C. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Segal, J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Tomada, A. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-06

    Free Electron Lasers opened a new window on imaging the motion of atoms and molecules. At SLAC, FEL experiments are performed at LCLS using 120Hz pulses with 1012 - 1013 photons in 10 femtoseconds (billions of times brighter than the most powerful synchrotrons). This extreme detection environment raises unique challenges, from obvious to surprising. Radiation damage is a constant threat due to accidental exposure to insufficiently attenuated beam, focused beam and formation of ice crystals reflecting the beam onto the detector. Often high power optical lasers are also used (e.g., 25TW), increasing the risk of damage or impeding data acquisition through electromagnetic pulses (EMP). The sample can contaminate the detector surface or even produce shrapnel damage. Some experiments require ultra high vacuum (UHV) with strict design, surface contamination and cooling requirements - also for detectors. The setup is often changed between or during experiments with short turnaround times, risking mechanical and ESD damage, requiring work planning, training of operators and sometimes continuous participation of the LCLS Detector Group in the experiments. The detectors used most often at LCLS are CSPAD cameras for hard x-rays and pnCCDs for soft x-rays.

  12. The ZEUS microvertex detector

    CERN Document Server

    Garfagnini, A

    1999-01-01

    A new vertex detector for the ZEUS experiment at HERA will be installed during the 1999-2000 shutdown, for the high-luminosity runs of HERA. It will allow to reconstruct secondary vertex tracks, coming from the decay of long-lived particles with a lifetime of about 10 sup - sup 1 sup 2 s, and improve the global momentum resolution of the tracking system. The interaction region will be surrounded with single-sided silicon strip detectors, with capacitive charge division: three double layers in the central region (600 detectors), and 4 'wheels' in the forward region (112 silicon planes). Due to the high number of readout channels, 512 readout strips per silicon plane in the barrel region and 480 in the forward part, and the large coverage of the vertex detector (almost 1 m long), the front-end electronics has to be placed on top of the detectors and has to be radiation tolerant since doses up to 2 kGy are expected near the interaction region. The HELIX chip has been chosen as analog chip with a low-noise, charg...

  13. Nonequilibrium superconducting detectors

    Science.gov (United States)

    Cristiano, R.; Ejrnaes, M.; Esposito, E.; Lisitskyi, M. P.; Nappi, C.; Pagano, S.; Perez de Lara, D.

    2006-03-01

    Nonequilibrium superconducting detectors exploit the early stages of the energy down cascade which occur after the absorption of radiation. They operate on a short temporal scale ranging from few microseconds down to tens of picoseconds. In such a way they provide fast counting capability, high time discrimination and also, for some devices, energy sensitivity. Nonequilibrium superconducting detectors are developed for their use both in basic science and in practical applications for detection of single photons or single ionized macromolecules. In this paper we consider two devices: distributed readout imaging detectors (DROIDs) based on superconducting tunnel junctions (STJs), which are typically used for high-speed energy spectroscopy applications, and hot-electron superconductive detectors (HESDs), which are typically used as fast counters and time discriminators. Implementation of the DROID geometry to use a single superconductor is discussed. Progress in the fabrication technology of NbN nanostructured HESDs is presented. The two detectors share the high sensitivity that makes them able to efficiently detect even single photons down to infrared energy.

  14. Nonequilibrium superconducting detectors

    Energy Technology Data Exchange (ETDEWEB)

    Cristiano, R [CNR-Istituto di Cibernetica E. Caianiello, 80078 Pozzuoli (Namibia) (Italy); Ejrnaes, M [CNR-Istituto di Cibernetica E. Caianiello, 80078 Pozzuoli (Namibia) (Italy); INFN Sezione di Napoli, 80126 Naples (Italy); Esposito, E [CNR-Istituto di Cibernetica E. Caianiello, 80078 Pozzuoli (Namibia) (Italy); Lisitskyi, M P [CNR-Istituto di Cibernetica E. Caianiello, 80078 Pozzuoli (Namibia) (Italy); Nappi, C [CNR-Istituto di Cibernetica E. Caianiello, 80078 Pozzuoli (Namibia) (Italy); Pagano, S [CNR-Istituto di Cibernetica E. Caianiello, 80078 Pozzuoli (Namibia) (Italy); Dipartimento di Fisica, Universita di Salerno, 84081 Baronissi (Saudi Arabia) (Italy); Perez de Lara, D [CNR-Istituto di Cibernetica E. Caianiello, 80078 Pozzuoli (Namibia) (Italy)

    2006-03-15

    Nonequilibrium superconducting detectors exploit the early stages of the energy down cascade which occur after the absorption of radiation. They operate on a short temporal scale ranging from few microseconds down to tens of picoseconds. In such a way they provide fast counting capability, high time discrimination and also, for some devices, energy sensitivity. Nonequilibrium superconducting detectors are developed for their use both in basic science and in practical applications for detection of single photons or single ionized macromolecules. In this paper we consider two devices: distributed readout imaging detectors (DROIDs) based on superconducting tunnel junctions (STJs), which are typically used for high-speed energy spectroscopy applications, and hot-electron superconductive detectors (HESDs), which are typically used as fast counters and time discriminators. Implementation of the DROID geometry to use a single superconductor is discussed. Progress in the fabrication technology of NbN nanostructured HESDs is presented. The two detectors share the high sensitivity that makes them able to efficiently detect even single photons down to infrared energy.

  15. Extended hard-sphere model and collisions of cohesive particles.

    Science.gov (United States)

    Kosinski, Pawel; Hoffmann, Alex C

    2011-09-01

    In two earlier papers the present authors modified a standard hard-sphere particle-wall and particle-particle collision model to account for the presence of adhesive or cohesive interaction between the colliding particles: the problem is of importance for modeling particle-fluid flow using the Lagrangian approach. This technique, which involves a direct numerical simulation of such flows, is gaining increasing popularity for simulating, e.g., dust transport, flows of nanofluids and grains in planetary rings. The main objective of the previous papers was to formally extend the impulse-based hard-sphere model, while suggestions for quantifications of the adhesive or cohesive interaction were made. This present paper gives an improved quantification of the adhesive and cohesive interactions for use in the extended hard-sphere model for cases where the surfaces of the colliding bodies are "dry," e.g., there is no liquid-bridge formation between the colliding bodies. This quantification is based on the Johnson-Kendall-Roberts (JKR) analysis of collision dynamics but includes, in addition, dissipative forces using a soft-sphere modeling technique. In this way the cohesive impulse, required for the hard-sphere model, is calculated together with other parameters, namely the collision duration and the restitution coefficient. Finally a dimensional analysis technique is applied to fit an analytical expression to the results for the cohesive impulse that can be used in the extended hard-sphere model. At the end of the paper we show some simulation results in order to illustrate the model.

  16. Hydration entropy change from the hard sphere model.

    Science.gov (United States)

    Graziano, Giuseppe; Lee, Byungkook

    2002-12-10

    The gas to liquid transfer entropy change for a pure non-polar liquid can be calculated quite accurately using a hard sphere model that obeys the Carnahan-Starling equation of state. The same procedure fails to produce a reasonable value for hydrogen bonding liquids such as water, methanol and ethanol. However, the size of the molecules increases when the hydrogen bonds are turned off to produce the hard sphere system and the volume packing density rises. We show here that the hard sphere system that has this increased packing density reproduces the experimental transfer entropy values rather well. The gas to water transfer entropy values for small non-polar hydrocarbons is also not reproduced by a hard sphere model, whether one uses the normal (2.8 A diameter) or the increased (3.2 A) size for water. At least part of the reason that the hard sphere model with 2.8 A size water produces too small entropy change is that the size of water is too small for a system without hydrogen bonds. The reason that the 3.2 A model also produces too small entropy values is that this is an overly crowded system and that the free volume introduced in the system by the addition of a solute molecule produces too much of a relief to this crowding. A hard sphere model, in which the free volume increase is limited by requiring that the average surface-to-surface distance between the solute and water molecules is the same as that between the increased-size water molecules, does approximately reproduce the experimental hydration entropy values.

  17. Symmetry in Sphere-Based Assembly Configuration Spaces

    Directory of Open Access Journals (Sweden)

    Meera Sitharam

    2016-01-01

    Full Text Available Many remarkably robust, rapid and spontaneous self-assembly phenomena occurring in nature can be modeled geometrically, starting from a collection of rigid bunches of spheres. This paper highlights the role of symmetry in sphere-based assembly processes. Since spheres within bunches could be identical and bunches could be identical, as well, the underlying symmetry groups could be of large order that grows with the number of participating spheres and bunches. Thus, understanding symmetries and associated isomorphism classes of microstates that correspond to various types of macrostates can significantly increase efficiency and accuracy, i.e., reduce the notorious complexity of computing entropy and free energy, as well as paths and kinetics, in high dimensional configuration spaces. In addition, a precise understanding of symmetries is crucial for giving provable guarantees of algorithmic accuracy and efficiency, as well as accuracy vs. efficiency trade-offs in such computations. In particular, this may aid in predicting crucial assembly-driving interactions. This is a primarily expository paper that develops a novel, original framework for dealing with symmetries in configuration spaces of assembling spheres, with the following goals. (1 We give new, formal definitions of various concepts relevant to the sphere-based assembly setting that occur in previous work and, in turn, formal definitions of their relevant symmetry groups leading to the main theorem concerning their symmetries. These previously-developed concepts include, for example: (i assembly configuration spaces; (ii stratification of assembly configuration space into configurational regions defined by active constraint graphs; (iii paths through the configurational regions; and (iv coarse assembly pathways. (2 We then demonstrate the new symmetry concepts to compute the sizes and numbers of orbits in two example settings appearing in previous work. (3 Finally, we give formal

  18. Sparsity-Aware Sphere Decoding: Algorithms and Complexity Analysis

    Science.gov (United States)

    Barik, Somsubhra; Vikalo, Haris

    2014-05-01

    Integer least-squares problems, concerned with solving a system of equations where the components of the unknown vector are integer-valued, arise in a wide range of applications. In many scenarios the unknown vector is sparse, i.e., a large fraction of its entries are zero. Examples include applications in wireless communications, digital fingerprinting, and array-comparative genomic hybridization systems. Sphere decoding, commonly used for solving integer least-squares problems, can utilize the knowledge about sparsity of the unknown vector to perform computationally efficient search for the solution. In this paper, we formulate and analyze the sparsity-aware sphere decoding algorithm that imposes $\\ell_0$-norm constraint on the admissible solution. Analytical expressions for the expected complexity of the algorithm for alphabets typical of sparse channel estimation and source allocation applications are derived and validated through extensive simulations. The results demonstrate superior performance and speed of sparsity-aware sphere decoder compared to the conventional sparsity-unaware sphere decoding algorithm. Moreover, variance of the complexity of the sparsity-aware sphere decoding algorithm for binary alphabets is derived. The search space of the proposed algorithm can be further reduced by imposing lower bounds on the value of the objective function. The algorithm is modified to allow for such a lower bounding technique and simulations illustrating efficacy of the method are presented. Performance of the algorithm is demonstrated in an application to sparse channel estimation, where it is shown that sparsity-aware sphere decoder performs close to theoretical lower limits.

  19. Statistical mechanics of the lattice sphere packing problem.

    Science.gov (United States)

    Kallus, Yoav

    2013-06-01

    We present an efficient Monte Carlo method for the lattice sphere packing problem in d dimensions. We use this method to numerically discover de novo the densest lattice sphere packing in dimensions 9 through 20. Our method goes beyond previous methods, not only in exploring higher dimensions but also in shedding light on the statistical mechanics underlying the problem in question. We observe evidence of a phase transition in the thermodynamic limit d→∞. In the dimensions explored in the present work, the results are consistent with a first-order crystallization transition but leave open the possibility that a glass transition is manifested in higher dimensions.

  20. ON THE FREE VIBRATION OF A SUBMERGED FGM HOLLOW SPHERE

    Institute of Scientific and Technical Information of China (English)

    Ye Guiru; Chen Weiqiu; Chen Weiqiu; Cai Jinbiao; Ding Haojiang

    2000-01-01

    The free vibration of a functionally graded material hollow sphere submerged in a compress ible fluid medium is exactly analyzed. The sphere is assumed to be spherically isotopic with material consta nts being inhomngenecus along the radial direction. By employing a separation technique as well as the spherical harmonics expansion method, the governing equations are simplified to an uncoupled second-order ordinary differential equation, and a coupled system of two such equations. Solutions to these equations are given when the elastic constants and the mass density are power functions of the radial coordinate. Numerical examples are finally given to show the effect of the material gradient on the natural frequencies.

  1. Convexity of Spheres in a Manifold without Conjugate Points

    Indian Academy of Sciences (India)

    Akhil Ranjan; Hemangi Shah

    2002-11-01

    For a non-compact, complete and simply connected manifold without conjugate points, we prove that if the determinant of the second fundamental form of the geodesic spheres in is a radial function, then the geodesic spheres are convex. We also show that if is two or three dimensional and without conjugate points, then, at every point there exists a ray with no focal points on it relative to the initial point of the ray. The proofs use a result from the theory of vector bundles combined with the index lemma.

  2. BUDGET MECHANISM IN REGULATING THE DEVELOPMENT OF THE SOCIAL SPHERE

    Directory of Open Access Journals (Sweden)

    Victoria Vitalievna Chaban

    2015-05-01

    Full Text Available The article reviewed and analyzed budget mechanism in regulating the development of the social sphere in Ukraine.The purpose of this article is to study the theoretical foundations of the functioning of the budgetary mechanism in regulating the development of the social sphere.When writing articles following methods were used: the statistical method of comparison and generalization, the dialectical method of deduction method.The results of the study can be used by the Ministry of Finance of Ukraine, the Verkhovna Rada of Ukraine, the Ministry of social policy of Ukraine.

  3. Stability index jump for cmc hypersurfaces of spheres

    CERN Document Server

    Perdomo, Oscar M

    2012-01-01

    It is known that the totally umbilical hypersurfaces in the (n+1)-dimensional spheres are characterized as the only hypersurfaces with weak stability index 0. That is, a compact hypersurface with constant mean curvature, cmc, in S^{n+1}, different from an Euclidean sphere, must have stability index greater than or equal to 1. In this paper we prove that the weak stability index of any non-totally umbilical compact hypersurface M\\subset S^{n+1} with cmc cannot take the values 1,2,3... n.

  4. Several Light Nulcie Evaluations Testing With LLNL Pulsed Sphere Benchmarks

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Huan-yu

    2012-01-01

    <正>In this work, Lawrence Livermore pulsed sphere experiments were modeled using Monte Carlo N-particle code (MCNP) for the purpose of benchmarking the new release of nuclear data librarys (CENDL-3[1], ENDF/B-Ⅶ.1[2], JENDL-4.0[3]). This program consisted of 12 different spheres, including 6 Li, 7Li, Be, C, N, O, LiD, Air, H2O, D2O, polythene and teflon. The calculated results were compared to experimental results[4-5].

  5. Slip and flow of hard-sphere colloidal glasses.

    Science.gov (United States)

    Ballesta, P; Besseling, R; Isa, L; Petekidis, G; Poon, W C K

    2008-12-19

    We study the flow of concentrated hard-sphere colloidal suspensions along smooth, nonstick walls using cone-plate rheometry and simultaneous confocal microscopy. In the glass regime, the global flow shows a transition from Herschel-Bulkley behavior at large shear rate to a characteristic Bingham slip response at small rates, absent for ergodic colloidal fluids. Imaging reveals both the "solid" microstructure during full slip and the local nature of the "slip to shear" transition. Both the local and global flow are described by a phenomenological model, and the associated Bingham slip parameters exhibit characteristic scaling with size and concentration of the hard spheres.

  6. Simulations of a supersymmetry inspired model on a fuzzy sphere

    OpenAIRE

    2008-01-01

    We present a numerical study of a two dimensional model of the Wess-Zumino type. We formulate this model on a sphere, where the fields are expanded in spherical harmonics. The sphere becomes fuzzy by a truncation in the angular momenta. This leads to a finite set of degrees of freedom without explicitly breaking the space symmetries. The corresponding field theory is expressed in terms of a matrix model, which can be simulated. We present first numerical results for the phase structure of a v...

  7. VMware vSphere 5.1 cookbook

    CERN Document Server

    GB, Abhilash

    2013-01-01

    A fast-paced, task-oriented Cookbook covering recipes on the installation and configuration of vSphere 5.1 components. The recipes are accompanied with relevant screenshots with an intention to provide a visual guidance as well. The book concentrates more on the actual task rather than the theory around it, making it easier to understand what is really needed to achieve the task.This book is a guide for anyone who wants to learn how to install and configure VMware vSphere components. This is an excellent handbook for support professionals or for anyone intending to give themselves a head start

  8. Free volume distribution of nearly jammed hard sphere packings

    Science.gov (United States)

    Maiti, Moumita; Sastry, Srikanth

    2014-07-01

    We calculate the free volume distributions of nearly jammed packings of monodisperse and bidisperse hard sphere configurations. These distributions differ qualitatively from those of the fluid, displaying a power law tail at large free volumes, which constitutes a distinct signature of nearly jammed configurations, persisting for moderate degrees of decompression. We reproduce and explain the observed distribution by considering the pair correlation function within the first coordination shell for jammed hard sphere configurations. We analyze features of the equation of state near jamming, and discuss the significance of observed asphericities of the free volumes to the equation of state.

  9. Animating Impacting Spheres with the Elastic Leidenfrost Effect

    Science.gov (United States)

    Waitukaitis, Scott; Souslov, Anton; van Hecke, Martin

    2016-11-01

    Liquid droplets impacting on hot surfaces above the Leidenfrost temperature can squeeze out the vapor layer and enter the contact boiling regime. What happens to soft but vaporizable solids, such as hydrogel spheres, under such conditions? I will show how this combination leads to sustained bouncing dynamics. The key physics is the coupling between the sphere's elastic deformations and vaporization. Beyond being a new facet of the Leidenfrost effect, this phenomenon promises to be useful in fields such as fluid dynamics, microfluidics, and active matter. NWO Veni and Vici Programs.

  10. A generalized hard-sphere model for Monte Carlo simulation

    Science.gov (United States)

    Hassan, H. A.; Hash, David B.

    1993-01-01

    A new molecular model, called the generalized hard-sphere, or GHS model, is introduced. This model contains, as a special case, the variable hard-sphere model of Bird (1981) and is capable of reproducing all of the analytic viscosity coefficients available in the literature that are derived for a variety of interaction potentials incorporating attraction and repulsion. In addition, a new procedure for determining interaction potentials in a gas mixture is outlined. Expressions needed for implementing the new model in the direct simulation Monte Carlo methods are derived. This development makes it possible to employ interaction models that have the same level of complexity as used in Navier-Stokes calculations.

  11. Unidirectional and Wavelength Selective Photonic Sphere-Array Nanoantennas

    CERN Document Server

    Liu, Yang G; Sha, Wei E I; Chew, Weng Cho

    2015-01-01

    We design a photonic sphere-array nanoantenna (NA) exhibiting both strong directionality and wavelength selectivity. Although the geometric configuration of the photonic NA resembles a plasmonic Yagi-Uda NA, it has different working principles, and most importantly, reduces the inherent metallic loss from plasmonic elements. For any selected optical wavelength, a sharp Fano-resonance by the reflector is tunable to overlap spectrally with a wider dipole resonance by the sphere-chain director leading to the high directionality. The work provides design principles for directional and selective photonic NAs, which is particularly useful for photon detection and spontaneous emission manipulation.

  12. JSATS Detector Field Manual

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Eric Y. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Flory, Adam E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lamarche, Brian L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Weiland, Mark A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-06-01

    The Juvenile Salmon Acoustic Telemetry System (JSATS) Detector is a software and hardware system that captures JSATS Acoustic Micro Transmitter (AMT) signals. The system uses hydrophones to capture acoustic signals in the water. This analog signal is then amplified and processed by the Analog to Digital Converter (ADC) and Digital Signal Processor (DSP) board in the computer. This board digitizes and processes the acoustic signal to determine if a possible JSATS tag is present. With this detection, the data will be saved to the computer for further analysis. This document details the features and functionality of the JSATS Detector software. The document covers how to install the software, setup and run the detector software. The document will also go over the raw binary waveform file format and CSV files containing RMS values

  13. Transition Radiation Detectors

    CERN Document Server

    Andronic, A

    2012-01-01

    We review the basic features of transition radiation and how they are used for the design of modern Transition Radiation Detectors (TRD). The discussion will include the various realizations of radiators as well as a discussion of the detection media and aspects of detector construction. With regard to particle identification we assess the different methods for efficient discrimination of different particles and outline the methods for the quantification of this property. Since a number of comprehensive reviews already exist, we predominantly focus on the detectors currently operated at the LHC. To a lesser extent we also cover some other TRDs, which are planned or are currently being operated in balloon or space-borne astro-particle physics experiments.

  14. OPERA: Electronic Detector

    CERN Document Server

    Jollet, C

    2010-01-01

    OPERA is an hybrid detector for the ni-tau appearance search in a direct way, and the Electronic Detectors (ED) have the crucial role of triggerring for the neutrino events and of localizing such an interaction inside the target. Another very important task of the ED is to identify the muon since only a correct matching of such a track with a track in the emulsion connected to the vertex of the event allows to reduce the charm background to the desired level. The ED, fully working since 2006, consist of a target tracker (scintillator strips) and a spectrometer (RPC and drift tubes). The different sub-detectors are de- scribed in the poster, as well as their performance both on Monte Carlo (MC) and real data.

  15. Cryogenic Tracking Detectors

    CERN Multimedia

    Luukka, P R; Tuominen, E M; Mikuz, M

    2002-01-01

    The recent advances in Si and diamond detector technology give hope of a simple solution to the radiation hardness problem for vertex trackers at the LHC. In particular, we have recently demonstrated that operating a heavily irradiated Si detector at liquid nitrogen (LN$_2$) temperature results in significant recovery of Charge Collection Efficiency (CCE). Among other potential benefits of operation at cryogenic temperatures are the use of large low-resistivity wafers, simple processing, higher and faster electrical signal because of higher mobility and drift velocity of carriers, and lower noise of the readout circuit. A substantial reduction in sensor cost could result The first goal of the approved extension of the RD39 program is to demonstrate that irradiation at low temperature in situ during operation does not affect the results obtained so far by cooling detectors which were irradiated at room temperature. In particular we shall concentrate on processes and materials that could significantly reduce th...

  16. Chemical potential of a test hard sphere of variable size in a hard-sphere fluid

    CERN Document Server

    Heyes, David M

    2016-01-01

    The Lab\\'ik and Smith Monte Carlo simulation technique to implement the Widom particle insertion method is extended using Molecular Dynamics (MD) instead to calculate numerically the insertion probability, $P_0(\\eta,\\sigma_0)$, of tracer hard-sphere (HS) particles of different diameters, $\\sigma_0$, in a host HS fluid of diameter $\\sigma$ and packing fraction, $\\eta$, up to $0.5$. It is shown analytically that the only polynomial representation of $-\\ln P_0(\\eta,\\sigma_0)$ consistent with the limits $\\sigma_0\\to 0$ and $\\sigma_0\\to\\infty$ has necessarily a cubic form, $c_0(\\eta)+c_1(\\eta)\\sigma_0/\\sigma+c_2(\\eta)(\\sigma_0/\\sigma)^2+c_3(\\eta)(\\sigma_0/\\sigma)^3$. Our MD data for $-\\ln P_0(\\eta,\\sigma_0)$ are fitted to such a cubic polynomial and the functions $c_0(\\eta)$ and $c_1(\\eta)$ are found to be statistically indistinguishable from their exact solution forms. Similarly, $c_2(\\eta)$ and $c_3(\\eta)$ agree very well with the Boubl\\'ik--Mansoori--Carnahan--Starling--Leland and Boubl\\'ik--Carnahan--Starling-...

  17. Chemical potential of a test hard sphere of variable size in a hard-sphere fluid

    Science.gov (United States)

    Heyes, David M.; Santos, Andrés

    2016-12-01

    The Labík and Smith Monte Carlo simulation technique to implement the Widom particle insertion method is applied using Molecular Dynamics (MD) instead to calculate numerically the insertion probability, P0(η ,σ0) , of tracer hard-sphere (HS) particles of different diameters, σ0, in a host HS fluid of diameter σ and packing fraction, η , up to 0.5. It is shown analytically that the only polynomial representation of -ln ⁡P0 (η ,σ0) consistent with the limits σ0→0 and σ0→∞ has necessarily a cubic form, c0(η ) +c1(η ) σ0 /σ +c2(η ) (σ0/σ ) 2 +c3(η ) (σ0/σ ) 3 . Our MD data for -ln ⁡P0 (η ,σ0) are fitted to such a cubic polynomial and the functions c0(η ) and c1(η ) are found to be statistically indistinguishable from their exact solution forms. Similarly, c2(η ) and c3(η ) agree very well with the Boublík-Mansoori-Carnahan-Starling-Leland and Boublík-Carnahan-Starling-Kolafa formulas. The cubic polynomial is extrapolated (high density) or interpolated (low density) to obtain the chemical potential of the host fluid, or σ0→σ , as β μex =c0+c1+c2+c3 . Excellent agreement between the Carnahan-Starling and Carnahan-Starling-Kolafa theories with our MD data is evident.

  18. Radiation Detectors and Art

    Science.gov (United States)

    Denker, Andrea

    The use of radiation detectors in the analysis of art objects represents a very special application in a true interdisciplinary field. Radiation detectors employed in this field detect, e.g., x-rays, γ-rays, β particles, and protons. Analyzed materials range from stones, metals, over porcelain to paintings. The available nondestructive and noninvasive analytical methods cover a broad range of techniques. Hence, for the sake of brevity, this chapter will concentrate on few techniques: Proton Induced X-ray Emission (PIXE) and Proton Induced γ-ray Emission (PIGE).

  19. Edgeless silicon pad detectors

    Science.gov (United States)

    Perea Solano, B.; Abreu, M. C.; Avati, V.; Boccali, T.; Boccone, V.; Bozzo, M.; Capra, R.; Casagrande, L.; Chen, W.; Eggert, K.; Heijne, E.; Klauke, S.; Li, Z.; Mäki, T.; Mirabito, L.; Morelli, A.; Niinikoski, T. O.; Oljemark, F.; Palmieri, V. G.; Rato Mendes, P.; Rodrigues, S.; Siegrist, P.; Silvestris, L.; Sousa, P.; Tapprogge, S.; Trocmé, B.

    2006-05-01

    We report measurements in a high-energy pion beam of the sensitivity of the edge region in "edgeless" planar silicon pad diode detectors diced through their contact implants. A large surface current on such an edge prevents the normal reverse biasing of the device, but the current can be sufficiently reduced by the use of a suitable cutting method, followed by edge treatment, and by operating the detector at low temperature. The depth of the dead layer at the diced edge is measured to be (12.5±8 stat..±6 syst.) μm.

  20. Edgeless silicon pad detectors

    Energy Technology Data Exchange (ETDEWEB)

    Perea Solano, B. [CERN, CH-1211 Geneva 23 (Switzerland)]. E-mail: blanca.perea.solano@cern.ch; Abreu, M.C. [LIP and University of Algarve, 8000 Faro (Portugal); Avati, V. [CERN, CH-1211 Geneva 23 (Switzerland); Boccali, T. [INFN Sez. di Pisa and Scuola Normale Superiore, Pisa (Italy); Boccone, V. [INFN Sez. di Genova and Universita di Genova, Genoa (Italy); Bozzo, M. [INFN Sez. di Genova and Universita di Genova, Genoa (Italy); Capra, R. [INFN Sez. di Genova and Universita di Genova, Genoa (Italy); Casagrande, L. [INFN Sez. di Roma 2 and Universita di Roma 2, Rome (Italy); Chen, W. [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Eggert, K. [CERN, CH-1211 Geneva 23 (Switzerland); Heijne, E. [CERN, CH-1211 Geneva 23 (Switzerland); Klauke, S. [CERN, CH-1211 Geneva 23 (Switzerland); Li, Z. [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Maeki, T. [Helsinki Institute of Physics, Helsinki (Finland); Mirabito, L. [CERN, CH-1211 Geneva 23 (Switzerland); Morelli, A. [INFN Sez. di Genova and Universita di Genova, Genoa (Italy); Niinikoski, T.O. [CERN, CH-1211 Geneva 23 (Switzerland); Oljemark, F. [Helsinki Institute of Physics, Helsinki (Finland); Palmieri, V.G. [Helsinki Institute of Physics, Helsinki (Finland); Rato Mendes, P. [LIP and University of Algarve, 8000 Faro (Portugal); Rodrigues, S. [LIP and University of Algarve, 8000 Faro (Portugal); Siegrist, P. [CERN, CH-1211 Geneva 23 (Switzerland); Silvestris, L. [INFN Sez. Di Bari, Bari (Italy); Sousa, P. [LIP and University of Algarve, 8000 Faro (Portugal); Tapprogge, S. [Helsinki Institute of Physics, Helsinki (Finland); Trocme, B. [Institut de Physique Nucleaire, Villeurbanne (France)

    2006-05-01

    We report measurements in a high-energy pion beam of the sensitivity of the edge region in 'edgeless' planar silicon pad diode detectors diced through their contact implants. A large surface current on such an edge prevents the normal reverse biasing of the device, but the current can be sufficiently reduced by the use of a suitable cutting method, followed by edge treatment, and by operating the detector at low temperature. The depth of the dead layer at the diced edge is measured to be (12.5{+-}8{sub stat.}.{+-}6{sub syst.}) {mu}m.

  1. ALICE Transition Radiation Detector

    CERN Multimedia

    Pachmayer, Y

    2013-01-01

    The Transition Radiation Detector (TRD) is the main electron detector in ALICE. In conduction with the TPC and the ITS, it provides the necessary electron identification capability to study: - Production of light and heavy vector mesons as well as the continuum in the di-electron channel, - Semi leptonic decays of hadrons with open charm and open beauty via the single-electron channel using the displaced vertex information provided by the ITS, - Correlated DD and BB pairs via coincidences of electrons in the central barrel and muons in the forward muon arm, - Jets with high Pτ tracks in one single TRD stack.

  2. A dual-detector extended range rem-counter

    CERN Document Server

    Ferrarini, M; Silari, M; Agosteo, S

    2010-01-01

    The design and characterization of a dual-detector spherical rem counter is discussed in this paper. The rem counter is based on a polythene sphere with lead and cadmium insets, designed to host at its centre either an active (He-3 SP9 proportional counter) or a passive (CR39 + B-10 radiator) thermal neutron detector. Its sensitivity ranges from thermal energies up to 1 GeV. A Monte Carlo characterization of this dual-detector rem counter has shown no significant change in the shape of the response curve obtained with the two detectors. The rem counter has been calibrated with a Pu-Be source. An intercomparison in a high-energy neutron field has been carried out at the CERF facility at CERN among the rem counter in the two configurations, two commercial units and the original version of the active LINUS in use at CERN. Both the active and passive versions of the rem counter agree, within the statistical uncertainties, with the CERN LINUS and with the facility reference values. Both versions of the instrument ...

  3. Status of the KEDR detector

    CERN Document Server

    Anashin, V V; Baibusinov, B O; Balashov, V; Baldin, E M; Barkov, L M; Barladyan, A K; Barnyakov, M Y; Baru, S E; Bedny, I; Beilin, D M; Blinov, A E; Blinov, V E; Bondarev, D V; Bondar, A E; Buzykaev, A R; Cantoni, P; Chilingarov, A G; Dneprovsky, L V; Eidelman, S I; Epifanov, D A; Frabetti, P L; Gaidarev, P B; Groshev, V R; Karpov, S V; Kiselev, V A; Klimenko, S G; Kolachev, G M; Kononov, S A; Kozlov, V N; Kravchenko, E A; Kulikov, V F; Kurdadze, L M; Kuzmin, A S; Kuznecov, S A; Lanni, F; Lelchuk, M Y; Leontiev, L A; Levichev, E B; Malyshev, V M; Manfredi, P F; Maslennikov, A L; Minakov, G D; Nagaslaev, V P; Naumenkov, A I; Nikitin, S A; Nomerotski, A; Onuchin, A P; Oreshkin, S B; Ovechkin, R; Palombo, F; Peleganchuk, S V; Petrosyan, S S; Pivovarov, S V; Poluektov, A O; Pospelov, G E; Protopopov, I Ya; Re, V; Romanov, L V; Root, N I; Ruban, A A; Savinov, G A; Shamov, A G; Shatilov, D; Shubin, M A; Shusharo, A I; Shwartz, B A; Sidorov, V A; Skovpen, Y I; Smakhtin, V P; Snopkov, R G; Sokolov, A V; Soukharev, A M; Talyshev, A A; Tayursky, V A; Telnov, V I; Tikhonov, Yu A; Todyshev, K Y; Usov, Y V; Vorobyev, A I; Yushkov, A N; Zatcepin, A V; Zhilich, V N

    2002-01-01

    KEDR is a general-purpose detector for experiments at the VEPP-4M e sup + e sup - -collider in the energy range 2E=2.0-12 GeV. All detector subsystems (except the aerogel Cherenkov counters) have been installed into the detector at VEPP-4M. Some preliminary data have been taken in the energy region of the J/PSI meson. The tuning of the detector and the VEPP-4M collider is in progress. Preliminary results on the detector performance are presented. The future experimental program for the KEDR detector is discussed.

  4. Status of the KEDR detector

    Energy Technology Data Exchange (ETDEWEB)

    Anashin, V.V.; Aulchenko, V.M.; Baibusinov, B.O.; Balashov, V.; Baldin, E.M.; Barkov, L.M.; Barladyan, A.K.; Barnyakov, M.Yu.; Baru, S.E.; Bedny, I.V.; Beilin, D.M.; Blinov, A.E.; Blinov, V.E.; Bondarev, D.V.; Bondar, A.E.; Buzykaev, A.R.; Cantoni, P.; Chilingarov, A.G.; Dneprovsky, L.V.; Eidelman, S.I.; Epifanov, D.A.; Frabetti, P.L.; Gaidarev, P.B.; Groshev, V.R.; Karpov, S.V.; Kiselev, V.A.; Klimenko, S.G.; Kolachev, G.M.; Kononov, S.A.; Kozlov, V.N.; Kravchenko, E.A.; Kulikov, V.F.; Kurdadze, L.M.; Kuzmin, A.S.; Kuznecov, S.A.; Lanni, F.; Lelchuk, M.Yu.; Leontiev, L.A.; Levichev, E.B.; Malyshev, V.M.; Manfredi, P.F.; Maslennikov, A.L.; Minakov, G.D.; Nagaslaev, V.P.; Naumenkov, A.; Nikitin, S.A.; Nomerotsky, A.; Onuchin, A.P.; Oreshkin, S.B.; Ovechkin, R.; Palombo, F.; Peleganchuk, S.V.; Petrosyan, S.S.; Pivovarov, S.V.; Poluektov, A.O.; Pospelov, G.E.; Protopopov, I.Ya.; Re, V.; Romanov, L.V.; Root, N.I.; Ruban, A.A.; Savinov, G.A.; Shamov, A.G.; Shatilov, D.; Shubin, M.A.; Shusharo, A.I.; Shwartz, B.A.; Sidorov, V.A.; Skovpen, Yu.I.; Smakhtin, V.P.; Snopkov, R.G.; Sokolov, A.V.; Soukharev, A.M.; Talyshev, A.A.; Tayursky, V.A.; Telnov, V.I.; Tikhonov, Yu.A. E-mail: tikhonov@cppm.in2p3.fr; Todyshev, K.Yu.; Usov, Yu.V.; Vorobyev, A.I.; Yushkov, A.N.; Zatcepin, A.V.; Zhilich, V.N

    2002-02-01

    KEDR is a general-purpose detector for experiments at the VEPP-4M e{sup +}e{sup -}-collider in the energy range 2E=2.0-12 GeV. All detector subsystems (except the aerogel Cherenkov counters) have been installed into the detector at VEPP-4M. Some preliminary data have been taken in the energy region of the J/{psi} meson. The tuning of the detector and the VEPP-4M collider is in progress. Preliminary results on the detector performance are presented. The future experimental program for the KEDR detector is discussed.

  5. The Upgraded D0 detector

    Energy Technology Data Exchange (ETDEWEB)

    Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, D.L.; Adams, M.; Adams, T.; Agelou, M.; Agram, J.-L.; Ahmed, S.N.; Ahn, S.H.; Ahsan, M.; Alexeev, G.D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G.A.; Anastasoaie, M.; Andeen, T.; Anderson, J.T.; Anderson, S.; /Buenos Aires U. /Rio de Janeiro, CBPF /Sao Paulo, IFT /Alberta U.

    2005-07-01

    The D0 experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid-argon calorimeters and central muon detector, remaining from Run I, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to D0.

  6. The Upgraded D0 Detector

    CERN Document Server

    Abazov, V M; Abolins, M; Acharya, B S; Adams, D L; Adams, M; Adams, T; Agelou, M; Agram, J L; Ahmed, S N; Ahn, S H; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Anastasoaie, M; Andeen, T; Anderson, J T; Anderson, S; Andrieu, B; Angstadt, R; Anosov, V; Arnoud, Y; Arov, M; Askew, A; Åsman, B; Assis-Jesus, A C S; Atramentov, O; Autermann, C; Avila, C; Babukhadia, L; Bacon, Trevor C; Badaud, F; Baden, A; Baffioni, S; Bagby, L; Baldin, B; Balm, P W; Banerjee, P; Banerjee, S; Barberis, E; Bardon, O; Barg, W; Bargassa, P; Baringer, P; Barnes, C; Barreto, J; Bartlett, J F; Bassler, U; Bhattacharjee, M; Baturitsky, M A; Bauer, D; Bean, A; Baumbaugh, B; Beauceron, S; Begalli, M; Beaudette, F; Begel, M; Bellavance, A; Beri, S B; Bernardi, G; Bernhard, R; Bertram, I; Besançon, M; Besson, A; Beuselinck, R; Beutel, D; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Binder, M; Biscarat, C; Bishoff, A; Black, K M; Blackler, I; Blazey, G; Blekman, F; Blessing, S; Bloch, D; Blumenschein, U; Bockenthein, E; Bodyagin, V; Böhnlein, A; Boeriu, O; Bolton, T A; Bonamy, P; Bonifas, D; Borcherding, F; Borissov, G; Bos, K; Bose, T; Boswell, C; Bowden, M; Brandt, A; Briskin, G; Brock, R; Brooijmans, G; Bross, A; Buchanan, N J; Buchholz, D; Bühler, M; Büscher, V; Burdin, S; Burke, S; Burnett, T H; Busato, E; Buszello, C P; Butler, D; Butler, J M; Cammin, J; Caron, S; Bystrický, J; Canal, L; Canelli, F; Carvalho, W; Casey, B C K; Casey, D; Cason, N M; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K M; Chandra, A; Chapin, D; Charles, F; Cheu, E; Chevalier, L; Chi, E; Chiche, R; Cho, D K; Choate, R; Choi, S; Choudhary, B; Chopra, S; Christenson, J H; Christiansen, T; Christofek, L; Churin, I; Cisko, G; Claes, D; Clark, A R; Clement, B; Clément, C; Coadou, Y; Colling, D J; Coney, L; Connolly, B; Cooke, M; Cooper, W E; Coppage, D; Corcoran, M; Coss, J; Cothenet, A; Cousinou, M C; Cox, B; Crepe-Renaudin, S; Cristetiu, M; Cummings, M A C; Cutts, D; Da Motta, H; Das, M; Davies, B; Davies, G; Davis, G A; Davis, W; De, K; de Jong, P; De Jong, S J; De La Cruz-Burelo, E; de La Taille, C; De Oliveira Martins, C; Dean, S; Degenhardt, J D; Déliot, F; Delsart, P A; Del Signore, K; De Maat, R; Demarteau, M; Demina, R; Demine, P; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Doets, M; Doidge, M; Dong, H; Doulas, S; Dudko, L V; Duflot, L; Dugad, S R; Duperrin, A; Dvornikov, O; Dyer, J; Dyshkant, A; Eads, M; Edmunds, D; Edwards, T; Ellison, J; Elmsheuser, J; Eltzroth, J T; Elvira, V D; Eno, S; Ermolov, P; Eroshin, O V; Estrada, J; Evans, D; Evans, H; Evdokimov, A; Evdokimov, V N; Fagan, J; Fast, J; Fatakia, S N; Fein, D; Feligioni, L; Ferapontov, A V; Ferbel, T; Ferreira, M J; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Fleck, I; Fitzpatrick, T; Flattum, E; Fleuret, F; Flores, R; Foglesong, J; Fortner, M; Fox, H; Franklin, C; Freeman, W; Fu, S; Fuess, S; Gadfort, T; Galea, C F; Gallas, E; Galyaev, E; Gao, M; García, C; García-Bellido, A; Gardner, J; Gavrilov, V; Gay, A; Gay, P; Gelé, D; Gelhaus, R; Genser, K; Gerber, C E; Gershtein, Yu; Gillberg, D; Geurkov, G; Ginther, G; Gobbi, B; Goldmann, K; Golling, T; Gollub, N; Golovtsov, V L; Gómez, B; Gómez, G; Gómez, R; Goodwin, R W; Gornushkin, Y; Gounder, K; Goussiou, A; Graham, D; Graham, G; Grannis, P D; Gray, K; Greder, S; Green, D R; Green, J; Green, J A; Greenlee, H; Greenwood, Z D; Gregores, E M; Grinstein, S; Gris, P; Grivaz, J F; Groer, L; Grünendahl, S; Grünewald, M W; Gu, W; Guglielmo, J; Sen-Gupta, A; Gurzhev, S N; Gutíerrez, G; Gutíerrez, P; Haas, A; Hadley, N J; Haggard, E; Haggerty, H; Hagopian, S; Hall, I; Hall, R E; Han, C; Han, L; Hance, R; Hanagaki, K; Hanlet, P; Hansen, S; Harder, K; Harel, A; Harrington, R; Hauptman, J M; Hauser, R; Hays, C; Hays, J; Hazen, E; Hebbeker, T; Hebert, C; Hedin, D; Heinmiller, J M; Heinson, A P; Heintz, U; Hensel, C; Hesketh, G; Hildreth, M D; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hohlfeld, M; Hong, S J; Hooper, R; Hou, S; Houben, P; Hu, Y; Huang, J; Huang, Y; Hynek, V; Huffman, D; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jacquier, Y; Jaffré, M; Jain, S; Jain, V; Jakobs, K; Jayanti, R; Jenkins, A; Jesik, R; Jiang, Y; Johns, K; Johnson, M; Johnson, P; Jonckheere, A; Jonsson, P; Jöstlein, H; Jouravlev, N I; Juárez, M; Juste, A; Kaan, A P; Kado, M; Käfer, D; Kahl, W; Kahn, S; Kajfasz, E; Kalinin, A M; Kalk, J; Kalmani, S D; Karmanov, D; Kasper, J; Katsanos, I; Kau, D; Kaur, R; Ke, Z; Kehoe, R; Kermiche, S; Kesisoglou, S; Khanov, A; Kharchilava, A I; Kharzheev, Yu M; Kim, H; Kim, K H; Kim, T J; Kirsch, N; Klima, B; Klute, M; Kohli, J M; Konrath, J P; Komissarov, E V; Kopal, M; Korablev, V M; Kostritskii, A V; Kotcher, J; Kothari, B; Kotwal, A V; Koubarovsky, A; Kozelov, A V; Kozminski, J; Kryemadhi, A; Kuznetsov, O; Krane, J; Kravchuk, N; Krempetz, K; Krider, J; Krishnaswamy, M R; Krzywdzinski, S; Kubantsev, M A; Kubinski, R; Kuchinsky, N; Kuleshov, S; Kulik, Y; Kumar, A; Kunori, S; Kupco, A; Kurca, T; Kvita, J; Kuznetsov, V E; Kwarciany, R; Lager, S; Lahrichi, N; Landsberg, G L; Larwill, M; Laurens, P; Lavigne, B; Lazoflores, J; Le Bihan, A C; Le Meur, G; Lebrun, P; Lee, S W; Lee, W M; Leflat, A; Leggett, C; Lehner, F; Leitner, R; Leonidopoulos, C; Lévêque, J; Lewis, P; Li, J; Li, Q Z; Li, X; Lima, J G R; Lincoln, D; Lindenmeyer, C; Linn, S L; Linnemann, J; Lipaev, V V; Lipton, R; Litmaath, M; Lizarazo, J; Lobo, L; Lobodenko, A; Lokajícek, M; Lounis, A; Love, P; Lü, J; Lubatti, H J; Lucotte, A; Lueking, L; Luo, C; Lynker, M; Lyon, A L; Machado, E; Maciel, A K A; Madaras, R J; Mättig, P; Magass, C; Magerkurth, A; Magnan, A M; Maity, M; Makovec, N; Mal, P K; Malbouisson, H B; Malik, S; Malyshev, V L; Manakov, V; Mao, H S; Maravin, Y; Markley, D; Markus, M; Marshall, T; Martens, M; Martin, M; Martin-Chassard, G; Mattingly, S E K; Matulik, M; Mayorov, A A; McCarthy, R; McCroskey, R; McKenna, M; McMahon, T; Meder, D; Melanson, H L; Melnitchouk, A S; Mendes, A; Mendoza, D; Mendoza, L; Meng, X; Merekov, Y P; Merkin, M; Merritt, K W; Meyer, A; Meyer, J; Michaut, M; Miao, C; Miettinen, H; Mihalcea, D; Mikhailov, V; Miller, D; Mitrevski, J; Mokhov, N; Molina, J; Mondal, N K; Montgomery, H E; Moore, R W; Moulik, T; Muanza, G S; Mostafa, M; Moua, S; Mulders, M; Mundim, L; Mutaf, Y D; Nagaraj, P; Nagy, E; Naimuddin, M; Nang, F; Narain, M; Narasimhan, V S; Narayanan, A; Naumann, N A; Neal, H A; Negret, J P; Nelson, S; Neuenschwander, R T; Neustroev, P; Nöding, C; Nomerotski, A; Novaes, S F; Nozdrin, A; Nunnemann, T; Nurczyk, A; Nurse, E; O'Dell, V; O'Neil, D C; Oguri, V; Olis, D; Oliveira, N; Olivier, B; Olsen, J; Oshima, N; Oshinowo, B O; Oteroy-Garzon, G J; Padley, P; Papageorgiou, K; Parashar, N; Park, J; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Pawloski, G; Perea, P M; Pérez, E; Peters, O; Petroff, P; Petteni, M; Phaf, L; Piegaia, R; Pleier, M A; Podesta-Lerma, P L M; Podstavkov, V M; Pogorelov, Y; Pol, M E; Pompos, A; Polosov, P; Pope, B G; Popkov, E; Porokhovoy, S; Prado da Silva, W L; Pritchard, W; Prokhorov, I; Prosper, H B; Protopopescu, S D; Przybycien, M B; Qian, J; Quadt, A; Quinn, B; Ramberg, E; Ramirez-Gomez, R; Rani, K J; Ranjan, K; Rao, M V S; Rapidis, P A; Rapisarda, S; Raskowski, J; Ratoff, P N; Ray, R E; Reay, N W; Rechenmacher, R; Reddy, L V; Regan, T; Renardy, J F; Reucroft, S; Rha, J; Ridel, M; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F K; Robinson, S; Rodrigues, R F; Roco, M T; Rotolo, C; Royon, C; Rubinov, P; Ruchti, R; Rucinski, R; Rud, V I; Rusakovich, N; Russo, P; Sabirov, B; Sajot, G; Sánchez-Hernández, A; Sanders, M P; Santoro, A; Satyanarayana, B; Savage, G; Sawyer, L; Scanlon, T; Schaile, A D; Schamberger, R D; Scheglov, Y; Schellman, H; Schieferdecker, P; Schmitt, C; Schwanenberger, C; Schukin, A A; Schwartzman, A; Schwienhorst, R; Sen-Gupta, S; Severini, H; Shabalina, E; Shamim, M; Shankar, H C; Shary, V; Shchukin, A A; Sheahan, P; Shephard, W D; Shivpuri, R K; Shishkin, A A; Shpakov, D; Shupe, M; Sidwell, R A; Simák, V; Sirotenko, V I; Skow, D; Skubic, P L; Slattery, P F; Smith, D E; Smith, R P; Smolek, K; Snow, G R; Snow, J; Snyder, S; Söldner-Rembold, S; Song, X; Song, Y; Sonnenschein, L; Sopczak, A; Sorin, V; Sosebee, M; Soustruznik, K; Souza, M; Spartana, N; Spurlock, B; Stanton, N R; Stark, J; Steele, J; Stefanik, A; Steinberg, J L; Steinbruck, G; Stevenson, K; Stolin, V; Stone, A; Stoyanova, D A; Strandberg, J; Strang, M A; Strauss, M; Ströhmer, R; Strom, D; Strovink, M; Stutte, L; Sumowidagdo, S; Sznajder, A; Talby, M; Tentindo-Repond, S; Tamburello, P; Taylor, W; Telford, P; Temple, J; Terentyev, N K; Teterin, V; Thomas, E; Thompson, J; Thooris, B; Titov, M; Toback, D; Tokmenin, V V; Tolian, C; Tomoto, M; Tompkins, D; Toole, T; Torborg, J; Touze, F; Towers, S; Trefzger, T; Trincaz-Duvoid, S; Trippe, T G; Tsybychev, D; Tuchming, B; Tully, C; Turcot, A S; Tuts, P M; Utes, M; Uvarov, L; Uvarov, S; Uzunyan, S; Vachon, B; Van den Berg, P J; Van Gemmeren, P; Van Kooten, R; Van Leeuwen, W M; Varelas, N; Varnes, E W; Vartapetian, A H; Vasilyev, I A; Vaupel, M; Vaz, M; Verdier, P; Vertogradov, L S; Verzocchi, M; Vigneault, M; Villeneuve-Séguier, F; Vishwanath, P R; Vlimant, J R; Von Törne, E; Vorobyov, A; Vreeswijk, M; Vu-Anh, T; Vysotsky, V S; Wahl, H D; Walker, R; Wallace, N; Wang, L; Wang, Z M; Warchol, J; Warsinsky, M; Watts, G; Wayne, M; Weber, M; Weerts, H; Wegner, M; Wermes, N; Wetstein, M; White, A; White, V; Whiteson, D; Wicke, D; Wijnen, T A M; Wijngaarden, D A; Wilcer, N; Willutzki, H; Wilson, G W; Wimpenny, S J; Wittlin, J; Wlodek, T; Wobisch, M; Womersley, J; Wood, D R; Wyatt, T R; Wu, Z; Xie, Y; Xu, Q; Xuan, N; Yacoob, S; Yamada, R; Yan, M; Yarema, R J; Yasuda, T; Yatsunenko, Y A; Yen, Y; Yip, K; Yoo, H D; Yoffe, F; Youn, S W; Yu, J; Yurkewicz, A; Zabi, A; Zanabria, M; Zatserklyaniy, A; Zdrazil, M; Zeitnitz, C; Zhang, B; Zhang, D; Zhang, X; Zhao, T; Zhao, Z; Zheng, H; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zieminski, A; Zitoun, R; Zmuda, T; Zutshi, V; Zviagintsev, S; Zverev, E G; Zylberstejn, A

    2005-01-01

    The D0 experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid-argon calorimeters and central muon detector, remaining from Run I, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to D0.

  7. Near field acoustic holography with microphones mounted on a rigid sphere

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Moreno, Guillermo; Fernandez Grande, Efren;

    2008-01-01

    . This is potentially very useful for source identification. On the other hand a rigid sphere is somewhat more practical than an open sphere, and it is possible to modify the existing spherical NAH theory so that a similar sound field reconstruction can be made with an array of microphones flush-mounted on a rigid...... sphere. Rigid spheres with flush-mounted microphones are also used for beamforming, and it is known that they are advantageous compared with open spheres for this application. However, whereas beamforming is a far field technique NAH is a near field technique, and spherical NAH based on a rigid sphere...

  8. Detector Description Software for Simulation,Reconstruction and Visualisation

    Institute of Scientific and Technical Information of China (English)

    PedroArce

    2001-01-01

    This paper describes a software that reads the detector description from tagbased ASCII files and builds an independent detector representation (its only dependency being the CLHEP library) in transient mode,A second package uses this transient representation to build automatically a GEANT4 representation of the detector geometry and materials.The software supports and kind of element and material,including material mixtures built by giving the weight fractions,the volume fractions of the number of atoms of each component.The common solid shapes(box,cube,cone,sphere,polycone,polyhedra,…)can be used,as well as solids made from a boolean operation of another solids(addition,substraction and intersection),The geometry volumes can be placed through simple positioning or positioning several copies following a given formula,so that each copy can have different position and rotation,Also divisioning of a volume along one of its axis is supported for the basic solid shpaes. The Simulation,Reconstruction and Visualisation(ROOT based)software contain no detector data.Instead,this data is always accesed through a unique interface to the GEANT4 detector representation package,which manages the complicated parameterised positionings and divisions and returns GEANT4 independent objects.Both packages have been built following strict Software Engineering practices,that we also describe in the paper.The software has been used for the detector description of the PS214(HARP) experiment at CERN,which is taking data since april 2001,With minor modifications it is also been used for the GEANT4 simulation of the CMS experiment.

  9. Fast Detector Simulation Using Lelaps, Detector Descriptions in GODL

    Energy Technology Data Exchange (ETDEWEB)

    Langeveld, Willy; /SLAC

    2005-07-06

    Lelaps is a fast detector simulation program which reads StdHep generator files and produces SIO or LCIO output files. It swims particles through detectors taking into account magnetic fields, multiple scattering and dE/dx energy loss. It simulates parameterized showers in EM and hadronic calorimeters and supports gamma conversions and decays. In addition to three built-in detector configurations, detector descriptions can also be read from files in the new GODL file format.

  10. Weierstrass representations for harmonic morphisms on Euclidean spaces and spheres

    CERN Document Server

    Baird, P

    1995-01-01

    We construct large families of harmonic morphisms which are holomorphic with respect to Hermitian structures by finding heierarchies of Weierstrass-type representations. This enables us to find new examples of complex-valued harmonic morphisms from Euclidean spaces and spheres.

  11. Stokesian swimming of a sphere by radial helical surface wave

    CERN Document Server

    Felderhof, B U

    2016-01-01

    The swimming of a sphere by means of radial helical surface waves is studied on the basis of the Stokes equations. Explicit expressions are derived for the matrices characterizing the mean translational and rotational swimming velocities and the mean rate of dissipation to second order in the wave amplitude.

  12. Three-sphere swimmer in a nonlinear viscoelastic medium

    KAUST Repository

    Curtis, Mark P.

    2013-04-10

    A simple model for a swimmer consisting of three colinearly linked spheres attached by rods and oscillating out of phase to break reciprocal motion is analyzed. With a prescribed forcing of the rods acting on the three spheres, the swimming dynamics are determined analytically in both a Newtonian Stokes fluid and a zero Reynolds number, nonlinear, Oldroyd-B viscoelastic fluid with Deborah numbers of order one (or less), highlighting the effects of viscoelasticity on the net displacement of swimmer. For instance, the model predicts that the three-sphere swimmer with a sinusoidal, but nonreciprocal, forcing cycle within an Oldroyd-B representation of a polymeric Boger fluid moves a greater distance with enhanced efficiency in comparison with its motility in a Newtonian fluid of the same viscosity. Furthermore, the nonlinear contributions to the viscoelastic constitutive relation, while dynamically nontrivial, are predicted a posteriori to have no effect on swimmer motility at leading order, given a prescribed forcing between spheres. © 2013 American Physical Society.

  13. Improved transmittance measurement with a magnesium oxide coated integrating sphere

    Science.gov (United States)

    Bowman, R. L.; Spisz, E. W.

    1972-01-01

    Simple and convenient technique has been found for extending transmittance measurement capability of conventional magnesium oxide coated integrating sphere system at low (near ultraviolet) wavelengths. Technique can be used to determine effect of contaminants on window materials and can also be used for measurements on thermal control coatings and telescope mirrors.

  14. Wind velocity measurements under turbulent conditions using a sphere anemometer

    Energy Technology Data Exchange (ETDEWEB)

    Heisselmann, Hendrik; Hoelling, Michael; Schulte, Bianca; Peinke, Joachim [Institute of Physics, University of Oldenburg (Germany)

    2008-07-01

    A well known problem of cup anemometry is the so-called overspeeding due to its momentum of inertia. As in nature turbulent flow conditions are predominant, cup anemometry leads to a wrong estimation of wind speeds. While cup anemometers do not provide the necessary time resolution to measure high frequency wind fluctuations, hot-wire anemometers are easily damaged under rough weather conditions. Therefore a robust, fast responding sphere anemometer was developed. The anemometer uses the thrust generated by the drag force on a sphere mounted on a flexible rod to detect wind velocities in two dimensions. The deflection of the rod is proportional to the drag force and can be measured either by means of a light pointer or by use of strain gauges. The two different measurement techniques were compared. The dynamic behaviour of the thrust anemometer was studied under laboratory conditions using a wind gust generator. The characteristics of different sphere-types and different rod materials were evaluated in order to optimize the setup. Results of open air measurements with hot-wire anemometer, sonic anemometer and sphere anemometer were compared by statistical methods.

  15. Optimizing packing fraction in granular media composed of overlapping spheres.

    Science.gov (United States)

    Roth, Leah K; Jaeger, Heinrich M

    2016-01-28

    What particle shape will generate the highest packing fraction when randomly poured into a container? In order to explore and navigate the enormous search space efficiently, we pair molecular dynamics simulations with artificial evolution. Arbitrary particle shape is represented by a set of overlapping spheres of varying diameter, enabling us to approximate smooth surfaces with a resolution proportional to the number of spheres included. We discover a family of planar triangular particles, whose packing fraction of ϕ ∼ 0.73 is among the highest experimental results for disordered packings of frictionless particles. We investigate how ϕ depends on the arrangement of spheres comprising an individual particle and on the smoothness of the surface. We validate the simulations with experiments using 3D-printed copies of the simplest member of the family, a planar particle consisting of three overlapping spheres with identical radius. Direct experimental comparison with 3D-printed aspherical ellipsoids demonstrates that the triangular particles pack exceedingly well not only in the limit of large system size but also when confined to small containers.

  16. A New Perturbed Hard-Sphere Equation of State

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A new equation of state based on hard-sphere perturbed theory was developed. This equation combined the CS repulsive term and Guo-Du attractive term. Parameters of 38 substances were estimated, the pressure-volume-temperature properties were calculated and compared with two other equations. The results show that this equation is more accurate.

  17. The unsteady motion of a sphere in a viscoelastic fluid

    DEFF Research Database (Denmark)

    Becker, L.E.; McKinley, G. H.; Rasmussen, Henrik K.

    1994-01-01

    The motion of a sphere accelerating from rest along the center line of a cylindrical tube filled with a polyisobutylene (PIB) Boger fluid is examined both experimentally, using a digital imaging system, and numerically via a Lagrangian finite element method for single and multimode Oldroyd models...

  18. Nonpolytopal nonsimplicial lattice spheres with nonnegative toric g-vector

    CERN Document Server

    Billera, Louis J

    2011-01-01

    We construct many nonpolytopal nonsimplicial Gorenstein* meet semi-lattices with nonnegative toric g-vector, supporting a conjecture of Stanley. These are formed as Bier spheres over the face posets of multiplexes, polytopes constructed by Bisztriczky as generalizations of simplices.

  19. The Paneitz curvature problem on lower dimensional spheres

    CERN Document Server

    Ben-Ayed, M

    2003-01-01

    In this paper we prescribe a fourth order conformal invariant (the Paneitz curvature) on the n-spheres, with n is an element of left brace 5, 6 right brace. Using dynamical and topological methods involving the study of critical points at infinity of the associated variational problem, we prove some existence results.

  20. The scalar curvature problem on the four dimensional half sphere

    CERN Document Server

    Ben-Ayed, M; El-Mehdi, K

    2003-01-01

    In this paper, we consider the problem of prescribing the scalar curvature under minimal boundary conditions on the standard four dimensional half sphere. We provide an Euler-Hopf type criterion for a given function to be a scalar curvature for some metric conformal to the standard one. Our proof involves the study of critical points at infinity of the associated variational problem.

  1. "Sighting" the Public: Iconoclasm and Public Sphere Theory

    Science.gov (United States)

    Finnegan, Cara A.; Kang, Jiyeon

    2004-01-01

    This essay considers the ways that iconoclasm, or the will to control images and vision, appears in canonical and contemporary public sphere theory. John Dewey and Jurgen Habermas enact a paradoxical relation to visuality by repudiating a mass culture of images while preferring "good" images and vision. Yet even when advocating for good vision,…

  2. Hard sphere colloidal dispersions: Mechanical relaxation pertaining to thermodynamic forces

    NARCIS (Netherlands)

    Mellema, J.; Kruif, de C.G.; Blom, C.; Vrij, A.

    1987-01-01

    The complex viscosity of sterically stabilized (hard) silica spheres in cyclohexane has been measured between 80 Hz and 170 kHz with torsion pendulums and a nickel tube resonator. The observed relaxation behaviour can be attributed to the interplay of hydrodynamic and thermodynamic forces. The valid

  3. Everyday political talk in the internet-based public sphere

    NARCIS (Netherlands)

    Graham, Todd; Coleman, Stephen; Freelon, Deen

    2015-01-01

    Ever since the advent of the Internet, political communication scholars have debated its potential to facilitate and support public deliberation as a means of revitalizing and extending the public sphere. Much of the debate has focused on the medium’s potential in offering communicative spaces that

  4. A Temperature Total Fourier Series Solution For a Hollow Sphere

    Directory of Open Access Journals (Sweden)

    Mehdi Mahmudi Mehrizi

    2011-01-01

    Full Text Available In the following pages, we exhibit an analytical solution of a two-dimensional temperature field in a hollow sphere under total periodic boundary condition. The material is assumed to be homogeneous and isotropic with time-independent thermal properties. Till now periodic boundary condition was derived with a harmonic vibration, whereas there is a noticeable difference in the practical conditions with harmonic vibration. In this essay, by means of Fourier analysis, we imagine the outside total periodic boundary condition, as aggregate of harmonic vibrations . To solve the problem, first we imagine the boundary condition as constant values and with separation of variables; we can obtain temperature distribution in the  sphere. Then Duhamel's theorem is used to calculate temperature field under fully periodic boundary condition. For confirmation of accurate solution, we can compare the result for a harmonic vibration and those reported by others. Also, solutions for a hollow sphere were compared with other present references. At last we can obtain thermal stresses which is caused by temperature field in the hollow sphere.

  5. DEGREE 3 ALGEBRAIC MINIMAL SURFACES IN THE 3-SPHERE

    Institute of Scientific and Technical Information of China (English)

    Joe S.Wang

    2012-01-01

    We give a local analytic characterization that a minimal surface in the 3-sphere S3 (C) R4 defined by an irreducible cubic polynomial is one of the Lawson's minimal tori.This provides an alternative proof of the result by Perdomo (Characterization of order 3 algebraic immersed minimal surfaces of S3,Geom.Dedicata 129 (2007),23-34).

  6. Superconducting Sphere in an External Magnetic Field Revisited

    Science.gov (United States)

    Sazonov, Sergey N.

    2013-01-01

    The purpose of this article is to give the intelligible procedure for undergraduate students to grasp proof of the fact that the magnetic field outside the hollow superconducting sphere (superconducting shell) coincides with the field of a point magnetic dipole both when an uniform external magnetic field is applied as when a ferromagnetic sphere…

  7. Self-assembly in colloidal hard-sphere systems

    NARCIS (Netherlands)

    Filion, L.C.

    2011-01-01

    In this thesis, we examine the phase behaviour and nucleation in a variety of hard-sphere systems. In Chapter 1 we present a short introduction and describe some of the simulation techniques used in this thesis. One of the main difficulties in predicting the phase behaviour in colloidal, atomic and

  8. Transport properties of the Fermi hard-sphere system

    CERN Document Server

    Mecca, Angela; Benhar, Omar; Polls, Artur

    2015-01-01

    The transport properties of neutron star matter play an important role in a variety of astrophysical processes. We report the results of a calculation of the shear viscosity and thermal conductivity coefficients of the hard-sphere fermion system of degeneracy $\

  9. Simulating colloids with Baxter's adhesive hard sphere model

    NARCIS (Netherlands)

    Miller, M.A.; Frenkel, D.

    2004-01-01

    The structure of the Baxter adhesive hard sphere fluid is examined using computer simulation. The radial distribution function (which exhibits unusual discontinuities due to the particle adhesion) and static structure factor are calculated with high accuracy over a range of conditions and compared w

  10. Simulation of the adhesive-hard-sphere model

    NARCIS (Netherlands)

    Kranendonk, W.G.T.; Frenkel, D.

    1988-01-01

    Monte Carlo simulations of the three-dimensional sticky-hard-sphere system are presented. A new modified Monte Carlo algorithm has been developed which makes it possible to explore the phase diagram for a large region of both the packing fraction and the stickiness parameter t. The phase diagram is

  11. Transport properties of the rough hard sphere fluid.

    Science.gov (United States)

    Kravchenko, Olga; Thachuk, Mark

    2012-01-28

    Results are presented of a systematic study of the transport properties of the rough hard sphere fluid. The rough hard sphere fluid is a simple model consisting of spherical particles that exchange linear and angular momenta, and energy upon collision. This allows a study of the sole effect of particle rotation upon fluid properties. Molecular dynamics simulations have been used to conduct extensive benchmark calculations of self-diffusion, shear and bulk viscosity, and thermal conductivity coefficients. As well, the validity of several kinetic theory equations have been examined at various levels of approximation as a function of density and translational-rotational coupling. In particular, expressions from Enskog theory using different numbers of basis sets in the representation of the distribution function were tested. Generally Enskog theory performs well at low density but deviates at larger densities, as expected. The dependence of these expressions upon translational-rotational coupling was also examined. Interestingly, even at low densities, the agreement with simulation results was sometimes not even qualitatively correct. Compared with smooth hard sphere behaviour, the transport coefficients can change significantly due to translational-rotational coupling and this effect becomes stronger the greater the coupling. Overall, the rough hard sphere fluid provides an excellent model for understanding the effects of translational-rotational coupling upon transport coefficients.

  12. Sphere-based calibration method for trinocular vision sensor

    Science.gov (United States)

    Lu, Rui; Shao, Mingwei

    2017-03-01

    A new method to calibrate a trinocular vision sensor is proposed and two main tasks are finished in this paper, i.e. to determine the transformation matrix between each two cameras and the trifocal tensor of the trinocular vision sensor. A flexible sphere target with several spherical circles is designed. As the isotropy of a sphere, trifocal tensor of the three cameras can be determined exactly from the feature on the sphere target. Then the fundamental matrix between each two cameras can be obtained. Easily, compatible rotation matrix and translation matrix can be deduced base on the singular value decomposition of the fundamental matrix. In our proposed calibration method, image points are not requested one-to-one correspondence. When image points locates in the same feature are obtained, the transformation matrix between each two cameras with the trifocal tensor of trinocular vision sensor can be determined. Experiment results show that the proposed calibration method can obtain precise results, including measurement and matching results. The root mean square error of distance is 0.026 mm with regard to the view field of about 200×200 mm and the feature matching of three images is strict. As a sphere projection is not concerned with its orientation, the calibration method is robust and with an easy operation. Moreover, our calibration method also provides a new approach to obtain the trifocal tensor.

  13. Two-body quantum mechanical problem on spheres

    OpenAIRE

    2005-01-01

    The quantum mechanical two-body problem with a central interaction on the sphere ${\\bf S}^{n}$ is considered. Using recent results in representation theory an ordinary differential equation for some energy levels is found. For several interactive potentials these energy levels are calculated in explicit form.

  14. Rowlinson’s concept of an effective hard sphere diameter

    Science.gov (United States)

    Henderson, Douglas

    2010-01-01

    Attention is drawn to John Rowlinson’s idea that the repulsive portion of the intermolecular interaction may be replaced by a temperature-dependent hard sphere diameter. It is this approximation that made the development of perturbation theory possible for realistic fluids whose intermolecular interactions have a steep, but finite, repulsion at short separations. PMID:20953320

  15. Rowlinson's concept of an effective hard sphere diameter.

    Science.gov (United States)

    Henderson, Douglas

    2010-01-01

    Attention is drawn to John Rowlinson's idea that the repulsive portion of the intermolecular interaction may be replaced by a temperature-dependent hard sphere diameter. It is this approximation that made the development of perturbation theory possible for realistic fluids whose intermolecular interactions have a steep, but finite, repulsion at short separations.

  16. Spinning of a submicron sphere by Airy beams.

    Science.gov (United States)

    Kim, Kyoung-Youm; Kim, Saehwa

    2016-01-01

    We show that by employing two incoherent counter-propagating Airy beams, we can manipulate a submicron sphere to spin around a transverse axis. We can control not only the spinning speed, but also the direction of the spinning axis by changing the polarization directions of Airy beams.

  17. Building the Platform of Digital Earth with Sphere Split Bricks

    Directory of Open Access Journals (Sweden)

    WANG Jinxin

    2015-06-01

    Full Text Available Discrete global grids, a modeling framework for big geo-spatial data, is always used to build the Digital Earth platform. Based on the sphere split bricks (Earth system spatial grids, it can not only build the true three-dimensional digital Earth model, but also can achieve integration, fusion, expression and application of the spatial data which locates on, under or above the Earth subsurface. The theoretical system of spheroid geodesic QTM octree grid is discussed, including the partition principle, analysis of grid geometry features and coding/ decoding method etc, and a prototype system of true-3D digital Earth platform with the sphere split bricks is developed. The functions of the system mainly include the arbitrary sphere segmentation and the visualization of physical models of underground, surface and aerial entities. Results show that the sphere geodesic QTM octree grid has many application advantages, such as simple subdivision rules, the grid system neat, clear geometric features, strong applicability etc. In particular, it can be extended to the ellipsoid, so it can be used for organization, management, integration and application of the global spatial big data.

  18. Stokesian swimming of a sphere at low Reynolds number

    CERN Document Server

    Felderhof, B U

    2016-01-01

    Explicit expressions are derived for the matrices determining the mean translational and rotational swimming velocities and the mean rate of dissipation for Stokesian swimming at low Reynolds number of a distorting sphere in a viscous incompressible fluid. As an application an efficient helical propeller-type stroke is found and its properties are calculated.

  19. Microstructure and macroscopic properties of polydisperse systems of hard spheres

    NARCIS (Netherlands)

    Ogarko, Vitaliy Anatolyevich

    2014-01-01

    This dissertation describes an investigation of systems of polydisperse smooth hard spheres. This includes the development of a fast contact detection algorithm for computer modelling, the development of macroscopic constitutive laws that are based on microscopic features such as the moments of the

  20. Low Velocity Sphere Impact of a Soda Lime Silicate Glass

    Science.gov (United States)

    2011-10-01

    is calculated by z = a 2 R . (5) This allows for the estimation of the maximum force, Pmax, from a dynamic impact as described by Timoshenko ...and M. M. Chaudhri, “Impact of Small Steel Spheres on Glass Surfaces”, J. Mat. Sci., 12:1573-86 (1977). [4] S. Timoshenko and J. N. Goodier, Theory

  1. Synthesis and characterization of submicron-sized mesoporous aluminosilicate spheres

    Indian Academy of Sciences (India)

    Gautam Gundiah; M Eswaramoorthy; S Neeraj; Srinivasan Natarajan; C N R Rao

    2001-06-01

    Me soporous a luminosilicate spheres of 0 3-0 4 m diameter, with different Si/Al ratios, have been prepared by surfactant templating. Surface area of these materials is in the 510-970 m2g-1 range and pore diameter in the 15-20 Å range.

  2. First ALICE detectors installed!

    CERN Document Server

    2006-01-01

    Detectors to track down penetrating muon particles are the first to be placed in their final position in the ALICE cavern. The Alice muon spectrometer: in the foreground the trigger chamber is positioned in front of the muon wall, with the dipole magnet in the background. After the impressive transport of its dipole magnet, ALICE has begun to fill the spectrometer with detectors. In mid-July, the ALICE muon spectrometer team achieved important milestones with the installation of the trigger and the tracking chambers of the muon spectrometer. They are the first detectors to be installed in their final position in the cavern. All of the eight half planes of the RPCs (resistive plate chambers) have been installed in their final position behind the muon filter. The role of the trigger detector is to select events containing a muon pair coming, for instance, from the decay of J/ or Y resonances. The selection is made on the transverse momentum of the two individual muons. The internal parts of the RPCs, made o...

  3. Superconducting Single Photon Detectors

    NARCIS (Netherlands)

    Dorenbos, S.N.

    2011-01-01

    This thesis is about the development of a detector for single photons, particles of light. New techniques are being developed that require high performance single photon detection, such as quantum cryptography, single molecule detection, optical radar, ballistic imaging, circuit testing and fluoresc

  4. MUON DETECTORS: RPC

    CERN Multimedia

    P. Paolucci

    2012-01-01

    The RPC system is operating with a very high uptime, an average chamber efficiency of about 95% and an average cluster size around 1.8. The average number of active channels is 97.7%. Eight chambers are disconnected and forty are working in single-gap mode due to high-voltage problems. The total luminosity lost due to RPCs in 2012 is 88.46 pb–1. One of the main goals of 2012 was to improve the stability of the endcap trigger that is strongly correlated to the performances of the detector, due to the 3-out-3 trigger logic. At beginning of 2011 the instability of the detector efficiency was about 10%. Detailed studies found that this was mainly due to the strong correlation between the performance of the detector and the atmospheric pressure (P). Figure XXY shows the linear correlation between the average cluster size of the endcap chamber versus P. This effect is expected for gaseous detectors and can be reduced by correcting the applied high-voltage working point (HVapp) according to the followi...

  5. ALICE Silicon Pixel Detector

    CERN Multimedia

    Manzari, V

    2013-01-01

    The Silicon Pixel Detector (SPD) forms the innermost two layers of the 6-layer barrel Inner Tracking System (ITS). The SPD plays a key role in the determination of the position of the primary collision and in the reconstruction of the secondary vertices from particle decays.

  6. Sensitive hydrogen leak detector

    Science.gov (United States)

    Myneni, Ganapati Rao

    1999-01-01

    A sensitive hydrogen leak detector system using passivation of a stainless steel vacuum chamber for low hydrogen outgassing, a high compression ratio vacuum system, a getter operating at 77.5 K and a residual gas analyzer as a quantitative hydrogen sensor.

  7. B-factory detectors

    CERN Document Server

    Marlow, D R

    2002-01-01

    The designs of the recently commissioned BaBar and Belle B-Factory detectors are described. The discussion is organized around the methods and instruments used to detect the so-called gold-plated-mode B sup 0->J/PSI K sub S decays and related modes.

  8. Pixel detector insertion

    CERN Multimedia

    CMS

    2015-01-01

    Insertion of the Pixel Tracker, the 66-million-channel device used to pinpoint the vertex of each colliding proton pair, located at the heart of the detector. The geometry of CMS is a cylinder lying on its side (22 meters long and 15 meters high in dia

  9. The CLIC Vertex Detector

    CERN Document Server

    Dannheim, D

    2015-01-01

    The precision physics needs at TeV-scale linear electron-positron colliders (ILC and CLIC) require a vertex-detector system with excellent flavour-tagging capabilities through a meas- urement of displaced vertices. This is essential, for example, for an explicit measurement of the Higgs decays to pairs of b-quarks, c-quarks and gluons. Efficient identification of top quarks in the decay t → W b will give access to the ttH-coupling measurement. In addition to those requirements driven by physics arguments, the CLIC bunch structure calls for hit tim- ing at the few-ns level. As a result, the CLIC vertex-detector system needs to have excellent spatial resolution, full geometrical coverage extending to low polar angles, extremely low material budget, low occupancy facilitated by time-tagging, and sufficient heat removal from sensors and readout. These considerations challenge current technological limits. A detector concept based on hybrid pixel-detector technology is under development for the CLIC ver- tex det...

  10. High-resolution ionization detector and array of such detectors

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, Douglas S. (Ypsilanti, MI); Rojeski, Ronald A. (Pleasanton, CA)

    2001-01-16

    A high-resolution ionization detector and an array of such detectors are described which utilize a reference pattern of conductive or semiconductive material to form interaction, pervious and measurement regions in an ionization substrate of, for example, CdZnTe material. The ionization detector is a room temperature semiconductor radiation detector. Various geometries of such a detector and an array of such detectors produce room temperature operated gamma ray spectrometers with relatively high resolution. For example, a 1 cm.sup.3 detector is capable of measuring .sup.137 Cs 662 keV gamma rays with room temperature energy resolution approaching 2% at FWHM. Two major types of such detectors include a parallel strip semiconductor Frisch grid detector and the geometrically weighted trapezoid prism semiconductor Frisch grid detector. The geometrically weighted detector records room temperature (24.degree. C.) energy resolutions of 2.68% FWHM for .sup.137 Cs 662 keV gamma rays and 2.45% FWHM for .sup.60 Co 1.332 MeV gamma rays. The detectors perform well without any electronic pulse rejection, correction or compensation techniques. The devices operate at room temperature with simple commercially available NIM bin electronics and do not require special preamplifiers or cooling stages for good spectroscopic results.

  11. Fire Emulator/Detector Evaluator

    Data.gov (United States)

    Federal Laboratory Consortium — Description: The fire emulator/detector evaluator (FE/DE) is a computer-controlled flow tunnel used to re-create the environments surrounding detectors in the early...

  12. Fire Emulator/Detector Evaluator

    Data.gov (United States)

    Federal Laboratory Consortium — Description:The fire emulator/detector evaluator (FE/DE) is a computer-controlled flow tunnel used to re-create the environments surrounding detectors in the early...

  13. Procedure to measure the neutrons spectrum around a lineal accelerator for radiotherapy; Procedimiento para medir el espectro de los neutrones en torno a un acelerador lineal para radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R.; Hernandez D, V. M.; Letechipia de L, C. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98060 Zacatecas (Mexico); Benites R, J. L. [Servicios de Salud de Nayarit, Centro Estatal de Cancerologia, Calzada de la Cruz 116 Sur, 63000 Tepic, Nayarit (Mexico); Salas L, M. A., E-mail: fermineutron@yahoo.com [Universidad Autonoma de Zacatecas, Unidad Academica de Agronomia, Apdo. Postal 336, 98000 Zacatecas (Mexico)

    2013-10-15

    An experimental procedure was developed, by means of Bonner spheres, to measure the neutrons spectrum around Linacs of medical use that only requires of a single shot of the accelerator; to this procedure we denominate Planetary or Isocentric method. One of the problems associated to the neutrons spectrum measurement in a radiotherapy room with lineal accelerator is because inside the room a mixed, intense and pulsed radiation field takes place affecting the detection systems based on active detector; this situation is solved using a passive detector. In the case of the Bonner spheres spectrometer the active detector has been substituted by activation detectors, trace detectors or thermoluminescent dosimeters. This spectrometer uses several spheres that are situated one at a time in the measurement point, this way to have the complete measurements group the accelerator should be operated, under the same conditions, so many times like spheres have the spectrometer, this activity can consume a long time and in occasions due to the work load of Linac to complicate the measurement process too. The procedure developed in this work consisted on to situate all the spectrometer spheres at the same time and to make the reading by means of a single shot, to be able to apply this procedure, is necessary that before the measurements two characteristics are evaluated: the cross-talking of the spheres and the symmetry conditions of the neutron field. This method has been applied to determine the photo-neutrons spectrum produced by a lineal accelerator of medical use Varian ix of 15 MV to 100 cm of the isocenter located to 5 cm of depth of a solid water mannequin of 30 x 30 x 15 cm. The spectrum was used to determine the total flow and the environmental dose equivalent. (Author)

  14. Position sensitive solid state detectors

    Energy Technology Data Exchange (ETDEWEB)

    Schnatterly, S.E.; Husk, D.

    1986-05-15

    Solid state detectors have been used for years as high quantum efficiency detectors for visible light. In this paper the use of PDA and CCD, solid state detectors, in the X-ray region will be discussed. In particular examples of data in the soft X-ray region are presented. Finally the use of phosphor coatings to enhance the sensitivity of solid state detectors is described.

  15. Radiation detectors laboratory; Laboratorio de detectores de radiacion

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez J, F.J. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1997-07-01

    The Radiation detectors laboratory was established with the assistance of the International Atomic Energy Agency which gave this the responsibility to provide its services at National and regional level for Latin America and it is located at the ININ. The more expensive and delicate radiation detectors are those made of semiconductor, so it has been put emphasis in the use and repairing of these detectors type. The supplied services by this laboratory are: selection consultant, detectors installation and handling and associated systems. Installation training, preventive and corrective maintenance of detectors and detection systems calibration. (Author)

  16. Characterisations of GEM detector prototype

    Energy Technology Data Exchange (ETDEWEB)

    Patra, Rajendra Nath [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064, West Bengal (India); Nanda, Amit [School of Physical Sciences, National Institute of Science Education and Research, Jatni 752050 (India); Rudra, Sharmili [Department of Applied Physics, CU, 92, APC Road, Kolkata 700009, West Bengal (India); Bhattacharya, P.; Sahoo, Sumanya Sekhar [School of Physical Sciences, National Institute of Science Education and Research, Jatni 752050 (India); Biswas, S., E-mail: saikat.ino@gmail.com [School of Physical Sciences, National Institute of Science Education and Research, Jatni 752050 (India); Mohanty, B. [School of Physical Sciences, National Institute of Science Education and Research, Jatni 752050 (India); Nayak, T.K. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064, West Bengal (India); Sahu, P.K.; Sahu, S. [Institute of Physics, Sachivalaya Marg, P.O.: Sainik School, Bhubaneswar 751005, Odisha (India)

    2016-07-11

    At NISER-IoP detector laboratory an initiative is taken to build and test Gas Electron Multiplier (GEM) detectors for ALICE experiment. The optimisation of the gas flow rate and the long-term stability test of the GEM detector are performed. The method and test results are presented.

  17. ATLAS Detector : Performance and Upgrades

    CERN Document Server

    Oliveira Damazio, Denis; The ATLAS collaboration

    2016-01-01

    Describe the ATLAS detector and summarize most relevant and recent information about the detector performance in 2016 with LHC colliding bunches at sqrt(s)=13 TeV with luminosity above the nominal value. Describe the different upgrade phases previewed for the detector and main activities already ongoing.

  18. Workshops on radiation imaging detectors

    Energy Technology Data Exchange (ETDEWEB)

    Sochinskii, N.V.; Sun, G.C.; Kostamo, P.; Silenas, A.; Saynatjoki, A.; Grant, J.; Owens, A.; Kozorezov, A.G.; Noschis, E.; Van Eijk, C.; Nagarkar, V.; Sekiya, H.; Pribat, D.; Campbell, M.; Lundgren, J.; Arques, M.; Gabrielli, A.; Padmore, H.; Maiorino, M.; Volpert, M.; Lebrun, F.; Van der Putten, S.; Pickford, A.; Barnsley, R.; Anton, M.E.G.; Mitschke, M.; Gros d' Aillon, E.; Frojdh, C.; Norlin, B.; Marchal, J.; Quattrocchi, M.; Stohr, U.; Bethke, K.; Bronnimann, C.H.; Pouvesle, J.M.; Hoheisel, M.; Clemens, J.C.; Gallin-Martel, M.L.; Bergamaschi, A.; Redondo-Fernandez, I.; Gal, O.; Kwiatowski, K.; Montesi, M.C.; Smith, K

    2005-07-01

    This document gathers the transparencies that were presented at the international workshop on radiation imaging detectors. 9 sessions were organized: 1) materials for detectors and detector structure, 2) front end electronics, 3) interconnected technologies, 4) space, fusion applications, 5) the physics of detection, 6) industrial applications, 7) synchrotron radiation, 8) X-ray sources, and 9) medical and other applications.

  19. Characterizations of GEM detector prototype

    CERN Document Server

    Patra, Rajendra Nath; Rudra, Sharmili; Bhattacharya, P.; Sahoo, Sumanya Sekhar; Biswas, S.; Mohanty, B.; Nayak, T.K.; Sahu, P.K.; Sahu, S.

    2016-01-01

    At NISER-IoP detector laboratory an initiative is taken to build and test Gas Electron Multiplier (GEM) detectors for ALICE experiment. The optimisation of the gas flow rate and the long-term stability test of the GEM detector are performed. The method and test results are presented.

  20. Detector and System Developments for LHC Detector Upgrades

    CERN Document Server

    Mandelli, Beatrice; Guida, Roberto; Rohne, Ole; Stapnes, Steinar

    2015-05-12

    The future Large Hadron Collider (LHC) Physics program and the consequent improvement of the LHC accelerator performance set important challenges to all detector systems. This PhD thesis delineates the studies and strategies adopted to improve two different types of detectors: the replacement of precision trackers with ever increasingly performing silicon detectors, and the improvement of large gaseous detector systems by optimizing their gas mixtures and operation modes. Within the LHC tracker upgrade programs, the ATLAS Insertable B-layer (IBL) is the first major upgrade of a silicon-pixel detector. Indeed the overall ATLAS Pixel Detector performance is expected to degrade with the increase of luminosity and the IBL will recover the performance by adding a fourth innermost layer. The IBL Detector makes use of new pixel and front-end electronics technologies as well as a novel thermal management approach and light support and service structures. These innovations required complex developments and Quality Ass...