Bonner sphere spectrometer: A CONRAD project intercomparison
International Nuclear Information System (INIS)
The most widely used system in neutrons measurements for radiological protection is the Bonner Sphere Spectrometer (BSS). The BSS is applied to characterise neutron fields from thermal to hundreds of MeVs. The Nuclear Regulatory Authority of Argentina has developed and calibrated its own BSS system, which has been used in many Argentine facilities during the last eleven years when the regulatory activities have been carried out. Following this line of work, the present development has been done in the framework of the International Intercomparison ''Uncertainty Assessment in Computational Dosimetry: A Comparison of Approaches'', organised by the CONRAD project (Coordinated Network for Radiation Dosimetry). The aim of intercomparison was to study the response of a proposed widespread neutron spectrometer exposed to arbitrary neutron sources. With this goal in mind, the experimental system has been modelled in detail according to the provided layout. The modelled neutron spectrometer consists of 8 Bonner spheres made of high-density polyethylene (δ=0.95gc/m3). The spheres diameter range between 2' and 12' in addition to a 12' diameter leadloaded sphere. The defined active thermal neutron detector, a 6LiI(Eu) scintillation crystal, was according to provided dimensions (4 mm (diameter) by 4 mm (height)), and located at each sphere centre. Irradiation geometry has been according to measurements carried out during the experimental part of the intercomparison. The theoretical neutron response has been calculated applying the well-known MCNPX code. The complete response matrix of the system has been obtained in the energy range between thermal neutron and 17.77 MeV. The obtained system theoretical response to ISO standard 241Am-Be and 252Cf sources shows an excellent agreement with experimental results provided by EURADOS. This response can be used to calibrate the system. The obtained matrix response can be coupled to any unfolding code to complete the BSS system used in
A Bonner Sphere Spectrometer for pulsed fields.
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. PMID:25948828
The response of a Bonner sphere spectrometer to charged hadrons
International Nuclear Information System (INIS)
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. (authors)
Measurement with Bonner spheres spectrometer in pulsed neutron fields
Czech Academy of Sciences Publication Activity Database
Králik, M.; Turek, Karel; Vondráček, V.; Krása, Josef; Velyhan, Andriy; Scholz, M.; Ivanova-Stanik, I.M.
2010-01-01
Roč. 45, č. 10 (2010), s. 1245-1249. ISSN 1350-4487. [Neutron and Ion Dosimetry Symposium /11./. Cape Town, 12.10.2009-16.10.2009] Institutional research plan: CEZ:AV0Z10480505; CEZ:AV0Z10100523 Keywords : neutron spectrometry * bonner spheres * track detector s Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.019, year: 2010
Photoneutron spectrum measured with a Bonner sphere spectrometer in planetary method mode
International Nuclear Information System (INIS)
The spectrum of photoneutrons produced by a 15 MV VARIAN iX linac working in Bremsstrahlung mode was measured a 100 cm from the IC located 5 cm-depth of a solid water phantom. The spectrum was measured with a Bonner spheres spectrometer with pairs of TLDs as thermal neutron detector. The measurements were carried out using the spectrometer in planetary method mode where a single shoot of the LINAC was required. - Highlights: • The photoneutrons spectrum of a 15 MV LINAC was measured. • A Bonner sphere spectrometer with pairs of TLDs were used. • Measurements were carried out with the BSS in Planetary method mode. • Measured spectrum is compared with calculated spectrum
Comparing standard Bonner spheres and high-sensitivity Bonner cylinders
International Nuclear Information System (INIS)
Standard Bonner spheres and proposed high-sensitivity Bonner cylinders were calibrated in a neutron calibration room, using a 252Cf source. The Bonner sphere system consists of 11 polyethylene (PE) spheres of various diameters and 4 extended spheres that comprise embedded metal shells. Similar to the design of Bonner spheres, a set of Bonner cylinders was assembled using a large cylindrical 3He tube as the central probe, which was wrapped using various thicknesses of PE. A layer of lead was employed inside one of the PE cylinders to increase the detection efficiency of high-energy neutrons. The central neutron probe used in the Bonner cylinders exhibited an efficiency of ∼17.9 times higher than that of the Bonner spheres. However, compared with the Bonner spheres, the Bonner cylinders are not fully symmetric in their geometry, exhibiting angular dependence in their responses to incoming neutrons. Using a series of calculations and measurements, this study presents a systematic comparison between Bonner spheres and cylinders in terms of their response functions, detection efficiencies, angular dependences and spectrum unfolding. A high-sensitivity Bonner cylinder spectrometer was developed to facilitate neutron spectrum measurement in low-intensity environments such as the site boundaries of nuclear facilities or accelerators. The proposed spectrometer system comprises 11 cylinders of various PE thicknesses and an extended cylinder with an embedded lead shell. Compared with the standard Bonner spheres, the detection efficiency of the device increased by a factor of >10 because a large 3He tube was employed. However, the Bonner cylinders are not symmetric in their polar angle, and this causes the advantage of isotropic response to be lost. A systematic comparison was conducted between the standard Bonner spheres and the proposed Bonner cylinders, examining their response functions, calibration measurements, angular dependences and spectrum unfolding. (authors)
Monte Carlo calculation of the response matrix of a Bonner spheres spectrometer
International Nuclear Information System (INIS)
The Bonner spheres spectrometer is utilized to estimate the neutron spectrum of neutrons from thermal up to several MeV neutrons. Its response is increased to few GeV neutrons by introducing large Z materials as inner shells. To use the spectrometer a matrix response and an unfolding method are required; these are crucial to assure the quality of spectrometer output. The response matrix of a Bonner sphere spectrometer was calculated by use of the MCNP code. As thermal neutron counter the spectrometer has a 0.4 θ x 0.4 cm2 6LiI(Eu) scintillator which is located at the centre of a set of polyethylene spheres. The response functions were calculated for 0, 2, 3, 5, 8, 10, and 12 inches-diameter polyethylene spheres for neutrons whose energy goes from 10-8 to 100 MeV. For energies from 10-8 to 20 MeV the MCNP4C code was utilized while for neutrons from 20 to 100 MeV calculations were carried out with MCNPX code. The response functions were compared with those reported in the literature. (author)
Response Matrix of a Bonner Spheres Spectrometer with 3 He Detector
International Nuclear Information System (INIS)
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 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)
NEMUS--the PTB Neutron Multisphere Spectrometer Bonner spheres and more
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, ...
Test of the Bonner Sphere Spectrometer Response Matrix in the 252Cf Neutron Field
International Nuclear Information System (INIS)
Full text: Since its development in 1960, a Bonner sphere spectrometer (BSS) has been the only instrument, which enables the spectral neutron fluence to be measured in a wide range of energies from thermal up to 20 MeV. Its resolution is poor but sufficient for dosimetric specification of neutron fields at workplaces. Experimentally determined BSS count rates depends mainly on the accuracy of the response matrix characterising certain type of BSS. At presemt the BSS response matrices are calculate by neutron transport Monte Carlo codes which allow detailed description of the BSS setup. The best verification of calculated response matrix is a calibration of the BSS in fields of monoenergetic neutrons. As so as these fields are not simply achievable a simple method how to test quality of BSS response matrix in the neutron field of 252Cf source is described. Applying distance variation method we get count rates of the BSS in the 252Cf field from which contributions of scattered neutrons and influence of finite detector and source dimensions were removed. These count rates are compared with the integrals of pure 252Cf spectrum and responses for individual spheres of the BSS. Disagreement indicates for which sphere the response is not properly determined. (author)
International Nuclear Information System (INIS)
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 6LiI(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 3He 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 3He 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)
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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 http://nukeisit.gatech.edu/bums
International Nuclear Information System (INIS)
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
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.
Experimental tests of the Bonner Sphere spectrometer using filtered neutron beams
International Nuclear Information System (INIS)
The operation of a Bonner Sphere neutron detector system has been tested using several unqiue neutron sources. Filtered neutron beams at beamport F at the University of Missouri Research Reactor (MURR) were used as a source of known quasi-monoenergetic neutrons for precise energy spectra analysis and calibration. A PuBe neutron source was used for absolute flux magnitude and spectral verification. Two computer codes, SWIFT and Least Squares Unfolding Techniques (LSUT), were used to unfold the experimental data. Several operational problems were encountered during these tests. First, many of the measurements involved neutron beam measurements in which the beams had a smaller diameter than the moderating spheres. This caused partial illumination of the spheres for which correction factors had to be developed. A partial illumination correction factor has been proposed and tested to account for this problem. Second, reactor core gamma-ray contamination in the neutron beams was of sufficient magnitude to interfere with some measurements. Gamma-ray background subtraction techniques using a multi-channel analyzer were used to alleviate this problem. After correcting for gamma-ray background and applying partial illumination correction factors, unfolded neutron spectra from the unfolding codes gave good results for most neutron sources. In particular the SWIFT results were quite good, exceeding expectations in terms of energy resolution and spectral accuracy. (orig.)
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Experimental activities are underway at INFN Legnaro National Laboratories (LNL) (Padua, Italy) and Pisa University aimed at angular-dependent neutron energy spectra measurements produced by the 9Be(p,xn) reaction, under a 5 MeV proton beam. This work has been performed in the framework of INFN TRASCO-BNCT project. Bonner Sphere Spectrometer (BSS), based on 6LiI (Eu) scintillator, was used with the shadow-cone technique. Proper unfolding codes, coupled to BSS response function calculated by Monte Carlo code, were finally used. The main results are reported here. - Highlights: • Bonner sphere spectrometer is used to determine the angular neutron energy spectrum of an accelerator-based BNCT facility. • The shadow-cone technique is a method used with Bonner sphere spectrometer to remove the neutron scattered contribution. • The response function matrix for the set of Bonner sphere spectrometer is calculated by Monte Carlo code. • Unfolding codes are used to obtain neutron spectra at different neutron emission angles (0°, 40°, 80° and 120°)
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
Measurement of cosmic ray neutrons with Bonner sphere spectrometer and neutron monitor at 79{sup o}N
Energy Technology Data Exchange (ETDEWEB)
Pioch, C., E-mail: christian.pioch@helmholtz-muenchen.d [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health (GmbH), Institute of Radiation Protection, Ingolstaedter Landstr. 1, 85764 Neuherberg (Germany); Mares, V. [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health (GmbH), Institute of Radiation Protection, Ingolstaedter Landstr. 1, 85764 Neuherberg (Germany); Vashenyuk, E.V.; Balabin, Yu.V. [Polar Geophysical Institute, Kola Science Center, Russian Academy of Sciences, Apatity (Russian Federation); Ruehm, W. [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health (GmbH), Institute of Radiation Protection, Ingolstaedter Landstr. 1, 85764 Neuherberg (Germany)
2011-01-21
In 2007, a Bonner spheres spectrometer (BSS) was installed in Ny-Alesund, Spitsbergen, at about 79{sup o}N. The spectrometer allows continuous measurement of the spectral fluence rate distribution of secondary neutrons from cosmic radiation in absolute terms. In this way, the system complements a neutron monitor (NM) that was installed in 2005, in Barentsburg, Spitsbergen, at about 78{sup o}N. To compare the readings of both systems, the NM response functions to neutrons and protons were calculated by means of the GEANT4 code, in the energy range between 10 meV and 100 GeV, and between 40 MeV and 10 GeV, respectively, using different intra-nuclear cascade (INC) models at energies above 20 MeV. Sample spectral fluence distributions as measured by means of the BSS system for neutrons in November and December 2007 were used and folded with the calculated GEANT4 NM response. The resulting calculated NM count rates were then compared to those actually measured by the NM system and a reasonable agreement between 7% and 43% was obtained, depending on the nuclear models used in the GEANT4 calculations and the assumed {sup 10}B enrichment of the NM counters used to detect the neutrons.
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. PMID:27203706
International Nuclear Information System (INIS)
One of the more actual and promising fields of applied neutron physics is the investigation of the malfunctions induced by high-energy neutrons naturally present in the atmosphere in electronic devices, called single event effects (SEE). These studies are of primary importance for the design of devices that have to fulfill high reliability requirements and those that are likely to be exposed to enhanced levels of cosmic rays background, e.g. in aerospace and avionic applications. Particle accelerators-driven neutron sources constitute valuable irradiation facilities for these purposes as they provide an opportunity for accelerated testing of the effects of these naturally occurring neutrons, provided the neutron spectrum is comparable with the atmospheric one and the neutron fields are known with high accuracy. The latter can be achieved through the use of appropriate radiation transport codes and neutron spectrometry techniques. In view of the design and construction of CHIPIR, a dedicated beam line for SEE studies at the ISIS pulsed neutron source second target station (UK) ((http://ts-2.isis.rl.ac.uk/instruments/phase2/index.htm)), a spectrometric characterization was performed on the VESUVIO beamline (Senesi et al.,2000). The spectrometric technique was the bonner sphere spectrometer (BSS), widely used to determine neutron spectra and dose quantities around high-energy accelerators. The experimental campaign provided a complete spectrometric investigation of the VESUVIO neutron beam, allowing the integral quantities (total fluence rate, fraction of fluence in given energy intervals) to be estimated with uncertainties lower than 10%.
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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 -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. (authors)
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The spectra of neutrons outside the plasma focus device PF-1000 with an upper energy limit of ≅1 MJ was measured using a Bonner spheres spectrometer in which the active detector of thermal neutrons was replaced by nine thermoluminescent chips. As an a priori spectrum for the unfolding procedure, the spectrum calculated by means of the Monte Carlo method with a simplified model of the discharge chamber was selected. Differences between unfolded and calculated spectra are discussed with respect to properties of the discharge vessel and the laboratory layout.
Hu, Z M; Xie, X F; Chen, Z J; Peng, X Y; Du, T F; Cui, Z Q; Ge, L J; Li, T; Yuan, X; Zhang, X; Hu, L Q; Zhong, G Q; Lin, S Y; Wan, B N; Gorini, G; Li, X Q; Zhang, G H; Chen, J X; Fan, T S
2014-11-01
To assess the neutron energy spectra and the neutron dose for different positions around the Experimental Advanced Superconducting Tokamak (EAST) device, a Bonner Sphere Spectrometer (BSS) was developed at Peking University, with totally nine polyethylene spheres and a SP9 (3)He counter. The response functions of the BSS were calculated by the Monte Carlo codes MCNP and GEANT4 with dedicated models, and good agreement was found between these two codes. A feasibility study was carried out with a simulated neutron energy spectrum around EAST, and the simulated "experimental" result of each sphere was obtained by calculating the response with MCNP, which used the simulated neutron energy spectrum as the input spectrum. With the deconvolution of the "experimental" measurement, the neutron energy spectrum was retrieved and compared with the preset one. Good consistence was found which offers confidence for the application of the BSS system for dose and spectrum measurements around a fusion device. PMID:25430324
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.
International Nuclear Information System (INIS)
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
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
International Nuclear Information System (INIS)
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 Eo and 90o with respect to the beam-line. Here the ERBSS of UAB (Universidad Autonoma de Barcelona-Grup de Fisica de les Radiacions) and INFN (Istituto Nazionale di Fisica 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.
Energy Technology Data Exchange (ETDEWEB)
Amgarou, K. [Grup de Recerca en Radiacions Ionitzants, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Bedogni, R., E-mail: roberto.bedogni@lnf.infn.it [INFN-Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Via E. Fermi n. 40, 00044 Frascati (Italy); Domingo, C. [Grup de Recerca en Radiacions Ionitzants, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Esposito, A.; Gentile, A.; Carinci, G. [INFN-Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Via E. Fermi n. 40, 00044 Frascati (Italy); Russo, S. [INFN-Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, via S. Sofia 44, 95123 Catania (Italy)
2011-10-21
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 E<20 MeV if only polyethylene spheres are used, but can be extended to hundreds of MeV by including metal-loaded spheres (extended range BSS, indicated with ERBSS). With the aim of providing useful data to the scientific community involved in neutron measurements at hadron therapy facilities, an ERBSS experiment was carried out at the Centro di AdroTerapia e Applicazioni Nucleari Avanzate (CATANA) of INFN-LNS (Laboratori Nazionali del Sud), where a proton beam routinely used for ophthalmic cancer treatments is available. The 62 MeV beam was directed towards a PMMA phantom, simulating the patient, and two neutron measurement points were established at 0{sup o} and 90{sup o} with respect to the beam-line. Here the ERBSS of UAB (Universidad Autonoma de Barcelona-Grup de Fisica de les Radiacions) and INFN (Istituto Nazionale di Fisica 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
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)
Measurement of spectrum and dose rate of natural neuron using Bonner spheres
International Nuclear Information System (INIS)
The natural neutron spectrum indoor was measured by using Bonner spheres spectrometer in Hefei. A Bonner sphere spectrometer with maximum entropy method was used to unfold neutron spectrum. Then according to the fluence to dose coefficient, the dose rate was calculated. The software EXPACS Ver2.21 based on the analytic methods for simulating the natural neutron spectrum was adopted to verify the neutron spectrum, and the BF3 natural neutron monitors were used to confirm the effective dose rate. The verification and analysis indicated that the results from Bonner spheres spectrometer consistent with others. The ambient dose equivalent rate of neutron in Hefei was between 2.6 nSv · h-1 and 14.38 nSv · h-1. (authors)
Real-Time Bonner Sphere Spectrometry on the HL-2A Tokamak
Jiang, Chunyu; Cao, Jing; Jiang, Xiaofei; Zhao, Yanfeng; Song, Xianying; Yin, Zejie
2016-06-01
Real-time Bonner sphere spectrometry (BSS) at the HL-2A tokamak for the neutron spectrum diagnostic is described. The spectrometer consists of eight different size Bonner spheres made of polyethylene and with a 3helium-filled detector in the center, pre-amplifiers, and parallel-processing data acquisition system (DAQ). Dynamic neutrons from plasma discharges of the HL-2A tokamak were measured and the real-time neutron spectrum was presented. supported by National Natural Science Foundation of China (No. 11375195) and the National Magnetic Confinement Fusion Science Program of China (No. 2013GB104003)
Application of Neural Networks for unfolding neutron spectra measured by means of Bonner Spheres
International Nuclear Information System (INIS)
A Neural Network structure has been used for unfolding neutron spectra measured by means of a Bonner Sphere Spectrometer set. The present work used the 'Stuttgart Neural Network Simulator' as the interface for designing, training and validation of a 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 10 MeV. Two types of neutron spectra were numerically investigated: monoenergetic and continuous. Good results were obtained, indicating that the Neural Network can be considered an interesting alternative among the neutron spectrum unfolding methodologies
NSDUAZ unfolding package for neutron spectrometry and dosimetry with Bonner spheres
International Nuclear Information System (INIS)
NSDUAZ (Neutron Spectrometry and Dosimetry for the Universidad Autonoma de Zacatecas) is a user friendly neutron unfolding package for Bonner sphere spectrometer with 6Lil(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 10-8 up to 231.2 MeV. (Author)
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)
Response matrix of an extended Bonner sphere system
International Nuclear Information System (INIS)
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 11C 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
Energy Technology Data Exchange (ETDEWEB)
Mazrou, Hakim [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz Fanon, B.P. 399, 16000 Alger (Algeria)], E-mail: mazrou_h@comena-dz.org; Sidahmed, Tassadit; Idiri, Zahir; Lounis-Mokrani, Zohra; Bedek, Said [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz Fanon, B.P. 399, 16000 Alger (Algeria); Allab, Malika [Faculte de Physique, Universite des Sciences et de la Technologie Houari-Boumediene (USTHB), Alger (Algeria)
2008-02-15
In the present work, measurements have been performed using an available multisphere neutron spectrometer based on a calibrated {sup 6}LiI scintillation detector (10mmox2mm) exposed to an {sup 241}Am-Be neutron source. Sensitive analysis has been performed to assess influence of angle and source-detector distances dependence on the detector responses. Our experimental responses were compared with the published experimental and calculated data for two {sup 241}Am-Be (ISO, PTB) neutron spectra with (4mmox4mm) {sup 6}LiI detector. A discrepancy by a factor of about two was achieved and it is chiefly due to the difference shown in active surface of both detectors.
Bonner sphere neutron spectrometry at spent fuel casks
Rimpler, A
2002-01-01
For transport and interim storage of spent fuel elements from power reactors and vitrified highly active waste (HAW) from reprocessing, various types of casks are used. The radiation exposure of the personnel during transportation and storage of these casks is caused by mixed photon-neutron fields and, frequently, the neutron dose is predominant. In operational radiation protection, survey meters and even personal dosemeters with imperfect energy dependence of the dose-equivalent response are used, i.e. the fluence response of the devices does not match the fluence-to-dose equivalent conversion function. In order to achieve more accurate dosimetric information and to investigate the performance of dosemeters, spectrometric investigations of the neutron fields are necessary. Therefore, fluence spectra and dose rates were measured by means of a simple portable Bonner multisphere spectrometer (BSS). The paper describes briefly the experimental set-up and evaluation procedure. Measured spectra for different locat...
NSDUAZ unfolding package for neutron spectrometry and dosimetry with Bonner spheres
International Nuclear Information System (INIS)
NSDUAZ (Neutron Spectrometry and Dosimetry from the Universidad Autónoma de Zacatecas) is a user friendly neutron unfolding package for Bonner sphere spectrometer with 6LiI(Eu) developed under LabView® 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 spectra to start the iterations. The NSDUAZ performance was evaluated using 252Cf, 252Cf/D2O, 241AmBe neutron sources and the neutrons outside the radial beam port of a TRIGA Mark III nuclear reactor running to 10 W. - Highlights: ► This paper presents the NSDUAZ unfolding package. ► Advantages and drawbacks of NSDUAZ package are pointed out. ► NSDUAZ is evaluated with neutrons from a nuclear reactor and isotopic neutron sources.
Investigation of the neutron spectrum of americium–beryllium sources by Bonner sphere spectrometry
International Nuclear Information System (INIS)
Americium–beryllium neutron sources are certainly the most widely used in neutron dosimetry laboratories, basically due to their long half-life and their energy distribution, which covers the energy domain of interest for many applications in ambient and personal dosimetry. Nevertheless, the spectrum of this source depends on the materials and dimension of the capsule and on the amount and physical–chemical properties of the active material, thus affecting relevant quantities such as the spectrum-averaged fluence-to-dose equivalent conversion coefficient. A EURAMET (European Association of National Metrology Institutes) project (n. 1104) was initiated to experimentally investigate how the neutron spectrum changes for different source sizes and encapsulations with a view to providing improved data for a planned revision of the ISO 8529 Standard Series. The experimental campaign was carried out in the low scatter facility at NPL. Here three different Bonner sphere spectrometers, BSSs, were exposed to the neutron fields produced by three different neutron sources formats: one X3 capsule (1 Ci) and two X14 capsules (10 Ci and 15 Ci). The specific advantage of the BSS is the large sensitivity to low-energy neutrons (E<0.1 MeV) which is the component expected to be most affected by the capsule-to-capsule variations and the component which is least well known. This paper summarises the results of the campaign with emphasis on (1) estimating the low-energy component of the Am–Be neutron spectrum, according to the encapsulation type; (2) evaluating the coherence between the Bonner spheres data and the previous studies performed with high-resolution spectrometers but limited in energy to E>0.1 MeV; (3) understanding whether the ISO-recommended Am–Be spectrum needs to be amended, and for which source formats
Investigation of the neutron spectrum of americium–beryllium sources by Bonner sphere spectrometry
Energy Technology Data Exchange (ETDEWEB)
Bedogni, R., E-mail: roberto.bedogni@lnf.infn.it [INFN—LNF (Frascati National Laboratories), Via E. Fermi n. 40, 00044 Frascati (Italy); Domingo, C. [GRRI, Departament de Fisica, Universitat Autónoma de Barcelona, E-08193 Bellaterra (Spain); Roberts, N.; Thomas, D.J. [National Physical Laboratory, Hampton Road, TW11 0LW Teddington, Middlesex (United Kingdom); Chiti, M.; Esposito, A. [INFN—LNF (Frascati National Laboratories), Via E. Fermi n. 40, 00044 Frascati (Italy); Garcia, M.J. [GRRI, Departament de Fisica, Universitat Autónoma de Barcelona, E-08193 Bellaterra (Spain); Gentile, A [INFN—LNF (Frascati National Laboratories), Via E. Fermi n. 40, 00044 Frascati (Italy); Liu, Z.Z. [National Physical Laboratory, Hampton Road, TW11 0LW Teddington, Middlesex (United Kingdom); San-Pedro, M. de [GRRI, Departament de Fisica, Universitat Autónoma de Barcelona, E-08193 Bellaterra (Spain)
2014-11-01
Americium–beryllium neutron sources are certainly the most widely used in neutron dosimetry laboratories, basically due to their long half-life and their energy distribution, which covers the energy domain of interest for many applications in ambient and personal dosimetry. Nevertheless, the spectrum of this source depends on the materials and dimension of the capsule and on the amount and physical–chemical properties of the active material, thus affecting relevant quantities such as the spectrum-averaged fluence-to-dose equivalent conversion coefficient. A EURAMET (European Association of National Metrology Institutes) project (n. 1104) was initiated to experimentally investigate how the neutron spectrum changes for different source sizes and encapsulations with a view to providing improved data for a planned revision of the ISO 8529 Standard Series. The experimental campaign was carried out in the low scatter facility at NPL. Here three different Bonner sphere spectrometers, BSSs, were exposed to the neutron fields produced by three different neutron sources formats: one X3 capsule (1 Ci) and two X14 capsules (10 Ci and 15 Ci). The specific advantage of the BSS is the large sensitivity to low-energy neutrons (E<0.1 MeV) which is the component expected to be most affected by the capsule-to-capsule variations and the component which is least well known. This paper summarises the results of the campaign with emphasis on (1) estimating the low-energy component of the Am–Be neutron spectrum, according to the encapsulation type; (2) evaluating the coherence between the Bonner spheres data and the previous studies performed with high-resolution spectrometers but limited in energy to E>0.1 MeV; (3) understanding whether the ISO-recommended Am–Be spectrum needs to be amended, and for which source formats.
International Nuclear Information System (INIS)
This research thesis first describes the problematic of the effects of natural radiation on micro- and nano-electronic components, and the atmospheric-radiative stress of atmospheric neutrons from cosmic origin: issue of 'Single event upsets', present knowledge of the atmospheric radiative environment induced by cosmic rays. The author then presents the neutron-based detection and spectrometry by using the Bonner sphere technique: principle of moderating spheres, definition and mathematical formulation of neutron spectrometry using Bonner spheres, active sensors of thermal neutrons, response of a system to conventional Bonner spheres, extension to the range of high energies. Then, he reports the development of a Bonner sphere system extended to the high-energy range for the spectrometry of atmospheric neutrons: definition of a conventional system, Monte Carlo calculation of response functions, development of the response matrix, representation and semi-empirical verification of fluence response, uncertainty analysis, extension to high energies, and measurement tests of the spectrometer. He reports the use of a Monte Carlo simulation to characterize the spectrometer response in the high-energy range
International Nuclear Information System (INIS)
The neutron response functions for a Bonner Sphere Spectrometer (BSS) with 3He proportional counter were calculated employing the MCNP and LAHET Monte Carlo codes for the neutron energy range from 10 MeV to 1 GeV. The MCNP calculations were extended up to 100 MeV using the neutron cross-sections from the transport data libraries LA-100 of LANL. The effect of the different physics models implemented in the LAHET code on the response of the Bonner spectrometer are documented and the possible reasons are discussed. The MCNP and LAHET results are also compared with calculations using the Monte Carlo high energy transport code HADRON. Verification experiments were conducted at the CERN high energy calibration facility which gave some insight to the question how appropriate the physical models are which are used for the calculation of the BSS responses. (author)
International Nuclear Information System (INIS)
The European Commission has funded within its 6th Framework Programme a three-year project (2005-2007) called CONRAD, COordinated Network for RAdiation Dosimetry. A major task of the CONRAD Work Package 'complex mixed radiation fields at workplaces' was to organise a benchmark exercise in a workplace field at a high-energy particle accelerator where neutrons are the dominant radiation component. The CONRAD benchmark exercise took place at the Gesellschaft fuer Schwerionenforschung mbH (GSI) in Darmstadt, Germany in July 2006. In this paper, the results of the spectrometry using four extended -range Bonner sphere spectrometers of four different institutes are reported. Outside Cave A the neutron spectra were measured with three spectrometers at six selected positions and ambient dose equivalent values were derived for use in the intercomparison with other area monitors and dosemeters. At a common position all three spectrometers were used to allow a direct comparison of their results which acts as an internal quality assurance. The comparison of the neutron spectra measured by the different groups shows very good agreement. A detailed analysis presents some differences between the shapes of the spectra and possible sources of these differences are discussed. However, the ability of Bonner sphere spectrometers to provide reliable integral quantities like fluence and ambient dose equivalent is well demonstrated in this exercise. The fluence and dose results derived by the three groups agree very well within the given uncertainties, not only with respect to the total energy region present in this environment but also for selected energy regions which contribute in certain strength to the total values. In addition to the positions outside Cave A one spectrometer was used to measure the neutron spectrum at one position in the entry maze of Cave A. In this case a comparison was possible to earlier measurements.
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...
International Nuclear Information System (INIS)
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 were obtained, indicating that the Neural Network can be considered an interesting alternative among the neutron spectrum unfolding methodologies. (author)
Study of reproducibility of measurements with the spectrometer of Bonner multispheres
Energy Technology Data Exchange (ETDEWEB)
Azevedo, G.A.; Pereira, W.W.; Patrao, K.C.S.; Fonseca, E.S., E-mail: geisadeazevedo@gmail.com, E-mail: walsan@ird.gov.br, E-mail: karla@ird.gov.br, E-mail: evaldo@ird.gov.br [Instituto de Radionprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)
2013-07-01
This work aims to study the metrological behavior of the Bonner Multisphere Spectrometer (BMS) of the LN / LNMRI / IRD - Laboratorio Metrologia de Neutrons / Laboratorio Nacional de Metrologia e Radiacao Ionizante / Instituto de Radioprotecao e Dosimetria, for measurements in repeatability and reproducibility conditions. Initially, a simulation was done by applying the Monte Carlo method, using the MCNP code and respecting the ISO 8529-1 (2001), using the sources of Californium ({sup 252} Cf), Americium-Beryllium ({sup 241} AmBe) and californium in heavy water (Cf + D{sub 2}O), all located at a distance of 100 cm from the neutron detector ({sup 6}Li (Eu) - crystal scintillator). In this program, the counting of neutrons that are captured by the detector was made. The source is located in the center of a sphere of radius 300 cm. Analyzes the impact of these neutrons in a point of the sphere wall, which in this case acted as a neutron detector and from there, it is estimated the number of neutrons that collide in the whole sphere. The purpose is to obtain the neutron count for different energy bands in a solid field of neutrons, since they have a spectrum ranging from a low to a high energy that can also vary within a particular environment. Wishes to obtain new fields with different sources and moderators materials to be used as new reference fields. Measurements are being conducted for these fields, with the aim of analyzing the variability conditions of the measurement (repeatability and reproducibility) in LEN - Laboratorio de Espectrometria de Neutrons of the LN/LMNRI/IRD. Thus, the spectrometer will be used to improve both the knowledge of the spectrum as the standard of neutrons of the lab, proving that a spectrometry is essential for correct measurement.
Comparison between standard unfolding and Bayesian methods in Bonner spheres neutron spectrometry
Energy Technology Data Exchange (ETDEWEB)
Medkour Ishak-Boushaki, G., 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); Allab, M. [Laboratoire SNIRM-Faculte de Physique, Universite des Sciences et de la Technologie Houari Boumediene, BP 32 El-Alia BabEzzouar, Algiers (Algeria)
2012-10-11
This paper compares the use of both standard unfolding and Bayesian methods to analyze data extracted from neutron spectrometric measurements with a view to deriving some integral quantities characterizing a neutron field. We consider, as an example, the determination of the total neutron fluence and dose in the vicinity of an Am-Be source from Bonner spheres measurements. It is shown that the Bayesian analysis provides a rigorous estimation of these quantities and their correlated uncertainties and overcomes difficulties encountered in the standard unfolding methods.
Comparison between standard unfolding and Bayesian methods in Bonner spheres neutron spectrometry
International Nuclear Information System (INIS)
This paper compares the use of both standard unfolding and Bayesian methods to analyze data extracted from neutron spectrometric measurements with a view to deriving some integral quantities characterizing a neutron field. We consider, as an example, the determination of the total neutron fluence and dose in the vicinity of an Am–Be source from Bonner spheres measurements. It is shown that the Bayesian analysis provides a rigorous estimation of these quantities and their correlated uncertainties and overcomes difficulties encountered in the standard unfolding methods.
Wiegel, B; Bedogni, R; Caresana, M; Esposito, A; Fehrenbacher, G; Ferrarini, M; Hohmann, E; Hranitzky, C; Kasper, A; Khurana, S; Mares, V; Reginatto, M; Rollet, S; Rühm, W; Schardt, D; Silari, M; Simmer, G; Weitzenegger, E
2009-01-01
The European Commission has funded within its 6th Framework Programme a three-year project (2005–2007) called CONRAD, COordinated Network for RAdiation Dosimetry. A major task of the CONRAD Work Package “complex mixed radiation fields at workplaces” was to organise a benchmark exercise in a workplace field at a high-energy particle accelerator where neutrons are the dominant radiation component. The CONRAD benchmark exercise took place at the Gesellschaft für Schwerionenforschung mbH (GSI) in Darmstadt, Germany in July 2006. In this paper, the results of the spectrometry using four extended -range Bonner sphere spectrometers of four different institutes are reported. Outside Cave A the neutron spectra were measured with three spectrometers at six selected positions and ambient dose equivalent values were derived for use in the intercomparison with other area monitors and dosemeters. At a common position all three spectrometers were used to allow a direct comparison of their results which acts as an int...
International Nuclear Information System (INIS)
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)
International Nuclear Information System (INIS)
A realistic geometry model of a Bonner sphere system with a spherical 3He-filled proportional counter and 12 polyethylene moderating spheres with diameters ranging from 7,62 cm (3'') to 45,72 cm (18'') is introduced. The MCNP Monte Carlo computer code is used to calculate the responses of this Bonner sphere system to monoenergetic neutrons in the energy range between 1 meV to 20 MeV. The relative uncertainties of the responses due to the Monte Carlo calculations are less than 1% for spheres up to 30,48 cm (12'') in diameter and less than 2% for the 15'' and 18'' spheres. Resonances in the carbon cross section are seen as significant structures in the response functions. Additional calculations were made to study the influence of the 3He number density and the polyethylene mass density on the response as well as the angular dependence of the Bonner sphere system. The calculated responses can be adjusted to a large set of calibration measurements with only a single fit factor common to all sphere diameters and energies. (orig.)
Scintillation forward spectrometer of the SPHERE setup
International Nuclear Information System (INIS)
The construction of the forward spectrometer for the 4π SPHERE setup to study multiple production of particles in nucleus-nucleus interactions is described. The measured parameters of the spectrometer detectors are presented. 7 refs.; 14 figs.; 1 tab
Spectral analysis of some fission neutron sources with the SOHO code from BONNER sphere data
International Nuclear Information System (INIS)
For several tests fission neutron sources particularly 252Cf bare and D2O moderated, we present some spectral analysis results obtained with the new iterative code SOHO from BONNER spheres data. The approximative solutions are obtained upon discretization of the Fredholm Equation of the first kind whose Resolution Function is experimentally known and mathematically defined by the Log-Normal Hypothesis given in our previous reports CEA-N--2241 (1981) and CEA-R--5181 (1982). The iterative procedure solve systems of non-exact homogeneous linear equations QX = e (by optimum liquidation of the residuals esub(i) with positivity constraint and absolute convergence, leading to an appropriate physical solution with a relative error in our tests typically of the order of a fraction of one percent for the INPUT - OUTPUT Data. For the applications to Health Physics the SOHO Code has been programmed for use with a HP-41 CV calculator
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. PMID:26508275
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. PMID:26133664
Comparison of measurements with active and passive Bonner sphere spectrometers
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...
International Nuclear Information System (INIS)
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. - Highlights: • Boric acid solution is useful to improve the energy resolution of Bonner sphere. • Uncertainty of the device configuration is critical for neutron spectrometry. • It is important to reduce and evaluate the uncertainty
International Nuclear Information System (INIS)
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 252Cf, 241AmBe and 239PuBe neutron sources measured with a Bonner spheres system
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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.
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...
Iterative code for the reconstruction of the neutrons spectrum using the Bonner spheres
International Nuclear Information System (INIS)
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)
Neutron measurements in the Vandellos II nuclear power plant with a Bonner sphere system
International Nuclear Information System (INIS)
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 Vandellos 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. (authors)
International Nuclear Information System (INIS)
The AECL Bonner Sphere Spectrometer (BSS) was taken to National Physical Laboratory (NPL) for calibration in mono-energetic neutron fields and bare 252Cf neutron fields. The mono-energetic radiations were performed using ISO-8529 prescribed neutron energies: 0.071, 0.144, 0.565, 1.2, 5 and 17 MeV. A central SP9 proportional counter was also evaluated at the NPL thermal neutron calibration facility in order to assess an effective pressure of 3He inside the counter, i.e. number density of 3He atoms. Based on these measurements and methods outlined by Thomas and Soochak, a new BSS response matrix was generated. The response matrix is then verified by unfolding spectra corresponding to various neutron fields. Those are NPL bare 252Cf source, National Institute of Standards and Technology bare and heavy water moderated 252Cf source and 241AmBe calibration source located at National Research Council. A good agreement was observed with expected neutron fluence rates, as well as derived dosimetric quantities, such as International Commission on Radiological Protection-74 ambient dose equivalent. The AECL BSS response matrix was created based on methods proposed by Wiegel et al., Thomas and Thomas and Soochak. The response matrix was further corrected for the mono-energetic neutron measurements taken and NPL. In order to experimentally verify the response matrix, four neutron measurements were taken at three laboratories: NPL, NIST and NRC. Good agreement with expected values both for integrated neutron fluence and derived dosimetric quantities was observed in all four cases. (authors)
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...
Quantification of neutron field at the neutron therapy room of KCCH using a Bonner sphere
International Nuclear Information System (INIS)
In order to quantify the neutron fields at the neutron therapy room of KCCH the Bonner Sphere spectrometry system (BS) was used for the measurement of neutron spectra produced from two kinds of Be targets (1.0 and 10.5 mm bombarded by protons of 35 and 45 MeV. It was found that additional neutrons produced from the beam line tube and the beam stopper, which are made of Aluminum, were included considerably as a part of neutron spectrum in the neutron field made from the thin (1.0 mm) Be target. Neutrons from the thick (10.5 mm) Be were hardened by a iron filter of 2.6 cm and collimated by the gantry, and the beam size was fitted 26 x 16 cm2) to cover the cross sectional area of a BS used in this measurement. Six kinds of neutron spectra were measured and the dosimetric quantities such as the fluence averaged energy (Eave.), the spectrum weighted dose conversion coefficient (h*) and the dose equivalent rate (H) per nano ampere were determined. These were ranged as follows, Eave. was from 4.3 to 15.1 MeV, and h* was from 326 to 447 pSv.cm2, and H was from 0.17 to 5.66 mSv.h-1.nA-1. The MXDFC31 code was used to unfold the measured data of BS and the MCNPX code (Ver. 2.4) implemented to calculate the default spectra which are necessary for unfolding as a prior information
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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)
International Nuclear Information System (INIS)
A conventional Bonner Sphere (BS) set consisting of six polyethylene spheres was modified to enhance its response to a high-energy neutron by putting a lead shell inside a polyethylene moderator. The response matrix of an extended BS was calculated using the MCNPX code and calibrated using a 252Cf neutron source. In order to survey the unknown photon and neutron mixed field, a spherical tissue equivalent proportional counter (TEPC) was constructed and assembled as a portable measurement system. The extended BS and the self-constructed TEPC were employed to determine the dosimetric quantities of the neutron field produced from the thick lead target bombarded by the 2.5 GeV electron beam of Pohang Accelerator Laboratory (PAL) and the neutron calibration field of Korea Atomic Energy Research Inst. (KAERI). (authors)
International Nuclear Information System (INIS)
A photon insensitive passive neutron spectrometer consisting of a single moderating polyethylene sphere with Dysprosium activation foils arranged along three perpendicular axes was designed by CIEMAT and INFN. The device is called Dy-SSS (Dy foil-based Single Sphere Spectrometer). It shows nearly isotropic response in terms of neutron fluence up to 20 MeV. The first prototype, previously calibrated with 14 MeV neutrons, has been recently tested in workplaces having different energy and directional distributions. These are a 2.5 MeV nearly mono-chromatic and mono-directional beam available at the ENEA Frascati Neutron Generator (FNG) and the photo-neutron field produced in a 15 MV Varian CLINAC DHX medical accelerator, located in the Ospedale S. Chiara (Pisa). Both neutron spectra are known through measurements with a Bonner Sphere Spectrometer. In both cases the experimental response of the Dy-SSS agrees with the reference data. Moreover, it is demonstrated that the spectrometric capability of the new device are independent from the directional distribution of the neutron field. This opens the way to a new generation of moderation-based neutron instruments, presenting all advantages of the Bonner sphere spectrometer without the disadvantage of the repeated exposures. This concept is being developed within the NESCOFI@BTF project of INFN (Commissione Scientifica Nazionale 5).
Bedogni, R.; Gómez-Ros, J. M.; Esposito, A.; Gentile, A.; Chiti, M.; Palacios-Pérez, L.; Angelone, M.; Tana, L.
2012-08-01
A photon insensitive passive neutron spectrometer consisting of a single moderating polyethylene sphere with Dysprosium activation foils arranged along three perpendicular axes was designed by CIEMAT and INFN. The device is called Dy-SSS (Dy foil-based Single Sphere Spectrometer). It shows nearly isotropic response in terms of neutron fluence up to 20 MeV. The first prototype, previously calibrated with 14 MeV neutrons, has been recently tested in workplaces having different energy and directional distributions. These are a 2.5 MeV nearly mono-chromatic and mono-directional beam available at the ENEA Frascati Neutron Generator (FNG) and the photo-neutron field produced in a 15 MV Varian CLINAC DHX medical accelerator, located in the Ospedale S. Chiara (Pisa). Both neutron spectra are known through measurements with a Bonner Sphere Spectrometer. In both cases the experimental response of the Dy-SSS agrees with the reference data. Moreover, it is demonstrated that the spectrometric capability of the new device are independent from the directional distribution of the neutron field. This opens the way to a new generation of moderation-based neutron instruments, presenting all advantages of the Bonner sphere spectrometer without the disadvantage of the repeated exposures. This concept is being developed within the NESCOFI@BTF project of INFN (Commissione Scientifica Nazionale 5).
Bedogni, Roberto; Pelliccioni, Maurizio; Esposito, Adolfo
2010-03-01
Due to the increased interest of the scientific community in the applications of synchrotron light, there is an increasing demand of high-energy electron facilities, testified by the construction of several new facilities worldwide. The radiation protection around such facilities requires accurate experimental methods to determine the dose due to prompt radiation fields. Neutron fields, in particular, are the most complex to measure, because they extend in energy from thermal (10 -8 MeV) up to hundreds MeV and because the responses of dosemeters and survey meters usually have large energy dependence. The Bonner Spheres Spectrometer (BSS) is in practice the only instrument able to respond over the whole energy range of interest, and for this reason it is frequently used to derive neutron spectra and dosimetric quantities in accelerator workplaces. Nevertheless, complex unfolding algorithms are needed to derive the neutron spectra from the experimental BSS data. This paper presents a parametric model specially developed for the unfolding of the experimental data measured with BSS around high-energy electron accelerators. The work consists of the following stages: (1) Generation with the FLUKA code, of a set of neutron spectra representing the radiation environment around accelerators with different electron energies; (2) formulation of a parametric model able to describe these spectra, with particular attention to the high-energy component (>10 MeV), which may be responsible for a large part of the dose in workplaces; and (3) implementation of this model in an existing unfolding code.
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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)
International Nuclear Information System (INIS)
Purpose: Secondary neutrons are an unavoidable consequence of proton therapy. While the neutron dose is low compared to the primary proton dose, its presence and contribution to the patient dose is nonetheless important. The most detailed information on neutrons includes an evaluation of the neutron spectrum. However, the vast majority of the literature that has reported secondary neutron spectra in proton therapy is based on computational methods rather than measurements. This is largely due to the inherent limitations in the majority of neutron detectors, which are either not suitable for spectral measurements or have limited response at energies greater than 20 MeV. Therefore, the primary objective of the present study was to measure a secondary neutron spectrum from a proton therapy beam using a spectrometer that is sensitive to neutron energies over the entire neutron energy spectrum. Methods: The authors measured the secondary neutron spectrum from a 250-MeV passively scattered proton beam in air at a distance of 100 cm laterally from isocenter using an extended-range Bonner sphere (ERBS) measurement system. Ambient dose equivalent H*(10) was calculated using measured fluence and fluence-to-ambient dose equivalent conversion coefficients. Results: The neutron fluence spectrum had a high-energy direct neutron peak, an evaporation peak, a thermal peak, and an intermediate energy continuum between the thermal and evaporation peaks. The H*(10) was dominated by the neutrons in the evaporation peak because of both their high abundance and the large quality conversion coefficients in that energy interval. The H*(10) 100 cm laterally from isocenter was 1.6 mSv per proton Gy (to isocenter). Approximately 35% of the dose equivalent was from neutrons with energies ≥20 MeV. Conclusions: The authors measured a neutron spectrum for external neutrons generated by a 250-MeV proton beam using an ERBS measurement system that was sensitive to neutrons over the entire
International Nuclear Information System (INIS)
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)
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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)
International Nuclear Information System (INIS)
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
International Nuclear Information System (INIS)
High-resolution neutron energy spectra, covering the entire energy range of interest, for two standard radionuclide neutron sources (241Am-B and 241Am-F) have been derived from Bonner sphere measurements by using high-resolution a priori data in the unfolding process. In each case, two a priori spectra were used, one from a two-stage calculation and also one from a combination of the calculated spectrum with a high-resolution measured spectrum. The unfolded spectra are compared with those published elsewhere and show significant differences from the ISO- and IAEA-recommended spectra for 241Am-B and 241Am-F, respectively. Values for the fluence-average energy and fluence-to-dose-equivalent conversion coefficients are presented for the new spectra, and the implications of the new spectra for the emission rates of the sources when measured by the manganese bath technique are also determined. A combination of calculations and measurements has been performed to determine the spectral fluence from two reference neutron sources over the entire energy range of interest. For the Am-B source, this approach has supported the spectra of Marsh et al. and Zimbal and reduced confidence in the ISO 8529 spectrum. However, in terms of derived quantities, there is a good agreement between all the available spectra. In contrast, the new Am-F spectrum presented here is significantly different from those already published. The fluence to dose conversion coefficients derived from the new spectrum are 9 % lower than the currently accepted values, and the emission rates of Am-F sources measured by the manganese bath technique may need to be increased by up to 0.5 %. (authors)
Simulation and calibration of the response function of multi-sphere neutron spectrometer
International Nuclear Information System (INIS)
In order to realize the on-line real-time measurement of neutron spectrum of ITER fusion, this paper presents a multi-sphere spectrometer system which consists of eight thermal neutron detectors, namely SP9 3He proportional counter, embedded in eight different diameter polyethylene spheres. The response function of eight polyethylene spheres of multi-sphere neutron spectrometer was calculated after the simulation of the neutron transport processes in multi-sphere spectrometer by adopting software Geant4. The peak of the response function is in the low energy region for smaller diameter polyethylene sphere. As the polyethylene sphere diameter increased, the peak of the response function moves to the high energy region. The experimental calibration adopts 241Am-Be neutron source. The relative error between normalized data of experiment 4π solid angle counts and normalized data of simulated detection efficiency of 4 in to 8 in polyethylene sphere is from 1.152% to 12.222%. The experimental results verify the response function of the simulation. All these results provide a theoretical and experimental basis for solving the on-line real-time neutron spectrum of ITER fusion. (authors)
Predicted performance of neutron spectrometers using scintillating fibers
International Nuclear Information System (INIS)
A variety of needs exists for knowing the energy spectral content of a neutron flux. Among these needs are arms-control and national-security applications, which arise because different neutron sources produce different neutron energy spectra. This work is primarily directed at these applications. The concept described herein is a spectrometer in the same sense as a Bonner sphere. The instrument response reflects a statistical average of the energy spectrum. The Bonner sphere is an early rendition of this class. In this, a neutron detector is placed at the center of a moderating (and absorbing) sphere (of varying thickness and composition). Spectral unfolding is required, and the resolution and efficiency are, typically, poor, although the potential bandwidth is very large. A recent variation on the Bonner-sphere approach uses 3He gas proportional counters with resistive wires to locate the position of the event (Toyokawa et al 1996). The spectrometer concept investigated here has the potential for better resolution and much improved neutron efficiency compared to Bonner spheres and similar devices. These improvements are possible because of the development of neutron-sensitive, scintillating-glass fibers. These fibers can be precisely located in space, which allows a corresponding precision in energy resolution. Also, they can be fabricated into arrays that intercept a large fraction of incident thermal neutrons, providing the improvement in neutron economy
Development of a portable neutron spectrometer
International Nuclear Information System (INIS)
A new portable neutron spectrometer has been developed for the evaluation of neutron background and the exposure dose in case of accident at the surrounding areas of power plants or accelerator facilities. This spectrometer consists of one Bonner sphere, a Position Sensitive 3He Proportional Counter (PSPC), an electronic circuit for pulse processing and a PC for spectrum unfolding and displaying. The total weight is 25.7 including boxes and cables. This spectrometer is small and light enough for high portability and available for obtaining accurate neutron spectra in the energy range between thermal and 15 MeV neutron. The Bonner sphere is minimized so as to evaluate a spectrum with reasonable accuracy and decided 23 cm in diameter of polyethylene. The PSPC was divided into 6 regions and one of the regions was outside of Bonner sphere to have higher sensitivity for thermal neutrons in the spectrum. The response functions for each regions were calculated using Monte Carlo Method. It was found that the unfolded spectrum data reasonably agreed with the slowing down neutron spectrum from 252Cf fission and would contribute to the exposure neutron dose estimation in case of accident. In this paper, the general specification and capability of this portable neutron spectrometer is described. (author)
International Nuclear Information System (INIS)
Bonner sphere measurements are presented for flights at altitudes of up to 12 km and geomagnetic latitudes between 26 deg.N and 86 deg.N and compared with results obtained by several survey meters. As an example of the natural neutron background near sea level, results from a recent longterm measurement campaign performed at the PTB site using an extended spectrometer are presented. The dependence of neutron fluence and ambient dose equivalent on the atmospheric pressure is demonstrated
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Guerrero Araque, J. E.; Mendez Villafane, R.
2013-07-01
This work intends to heavily describe simulation steps used in code MCNPX for calculation for Neutron response of a BSS with passive or active detector. Has it been calculated with MCNPX the matrix response of a system of Bonner spheres, with passive or active detector, which described in detail the steps to be followed by the code are part of the solution. (Author)
Neutron dosimetry in mixed fields with monoblock neutron spectrometer
International Nuclear Information System (INIS)
Full text: The multi-sphere method of neutron spectrometry or namely Bonner spheres neutron spectrometry is currently playing an increasing role in the mixed radiation field measurements. The growing popularity of this methodology is caused by its relative availability, simplicity of measurement in a wide energy range, high sensitivity and satisfactory gamma-ray suppression. These qualities allow the usage of multi-sphere neutron spectrometers for adequate characterization of neutron field, particularly reliable measurements of neutron dose rate. However, the main difficulties in the application of this kind of neutron detector are the perturbation of the neutron field, caused by the detector itself, and the complex procedure required for unfolding the neutron spectrum. Furthermore, it is necessary to perform a relatively high number of measurements, one for each spherical moderator (as a rule, 5-7 pieces). This in turn may require a dedicated source monitoring system, otherwise significant errors may occur. These requirements hamper the application of the multi-sphere spectrometry method to pulsed neutron sources, for example. Other difficulties occur in the characterization of reactor neutron beams, in case the beam diameter is smaller than those of the spherical moderators. In this situation it is necessary to carry out a beam scanning and integrate the acquired data. To improve the methodology of neutron field parameter measurement the Monoblock Neutron Spectrometer (MNS) has been developed recently. The basic idea of the novel detector is to determine the neutron energy spectrum by unfolding a set of count rates from thermal neutron detectors located at different depths in the common polyethylene moderator. The unfolding algorithms for neutron spectrum and neutron dose rates have been specifically improved for operation with MNS. The testing results with well-know neutron reference fields and reactor neutron beam are presented. The application of MNS for
Thomas N Bonner (1923-2003), medical historian.
Bickel, Marcel H
2016-05-01
Thomas Bonner made a long academic career, teaching medical history and higher education at several American universities and presiding over three of these. He engaged in politics for 2 years. As a historian of medicine, he published important books on topics including Midwestern medicine, medical education in the United States and in European countries, the entry of women into medicine in the 19th century and on the educator Abraham Flexner. His works were based on exhaustive research, penetrating analysis, language skills and the ability to explain complex information in understandable terms. Bonner lived a passionate life of commitment and devotion to various worthwhile causes. PMID:24986396
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.
Applicability of a Bonner Shere technique for pulsed neutron in 120 GeV proton facility
Energy Technology Data Exchange (ETDEWEB)
Sanami, T.; Hagiwara, M.; Iwase, H.; /KEK, Tsukuba; Iwamoto, Y.; Sakamoto, Y.; Nakashima, H.; /JAEA, Ibaraki; Arakawa, H.; Shigyo, N.; /Kyushu U.; Leveling, A.F.; Boehnlein, D.J.; Vaziri, K.; /Fermilab
2008-02-01
The data on neutron spectra and intensity behind shielding are important for radiation safety design of high-energy accelerators since neutrons are capable of penetrating thick shielding and activating materials. Corresponding particle transport codes--that involve physics models of neutron and other particle production, transportation, and interaction--have been developed and used world-wide [1-8]. The results of these codes have been ensured through plenty of comparisons with experimental results taken in simple geometries. For neutron generation and transport, several related experiments have been performed to measure neutron spectra, attenuation length and reaction rates behind shielding walls of various thicknesses and materials in energy range up to several hundred of MeV [9-11]. The data have been used to benchmark--and modify if needed--the simulation modes and parameters in the codes, as well as the reference data for radiation safety design. To obtain such kind of data above several hundred of MeV, Japan-Fermi National Accelerator Laboratory (FNAL) collaboration for shielding experiments has been started in 2007, based on suggestion from the specialist meeting of shielding, Shielding Aspects of Target, Irradiation Facilities (SATIF), because of very limited data available in high-energy region (see, for example, [12]). As a part of this shielding experiment, a set of Bonner sphere (BS) was tested at the antiproton production target facility (pbar target station) at FNAL to obtain neutron spectra induced by a 120-GeV proton beam in concrete and iron shielding. Generally, utilization of an active detector around high-energy accelerators requires an improvement on its readout to overcome burst of secondary radiation since the accelerator delivers an intense beam to a target in a short period after relatively long acceleration period. In this paper, we employ BS for a spectrum measurement of neutrons that penetrate the shielding wall of the pbar target
A real time scintillating fiber Time of Flight spectrometer for LINAC photoproduced neutrons
Maspero, M.; Berra, A.; Conti, V.; Giannini, G.; Ostinelli, A.; Prest, M.; Vallazza, E.
2015-03-01
The use of high-energy (> 8 MeV) LINear ACcelerators (LINACs) for medical cancer treatments causes the photoproduction of secondary neutrons, whose unwanted dose to the patient has to be calculated. The characterization of the neutron spectra is necessary to allow the dosimetric evaluation of the neutron beam contamination. The neutron spectrum in a hospital environment is usually measured with integrating detectors such as bubble dosimeters, Thermo Luminescent Dosimeters (TLDs) or Bonner Spheres, which integrate the information over a time interval and an energy one. This paper presents the development of a neutron spectrometer based on the Time of Flight (ToF) technique in order to perform a real time characterization of the neutron contamination. The detector measures the neutron spectrum exploiting the fact that the LINAC beams are pulsed and arranged in bunches with a rate of 100-300 Hz depending on the beam type and energy. The detector consists of boron loaded scintillating fibers readout by a MultiAnode PhotoMultiplier Tube (MAPMT). A detailed description of the detector and the acquisition system together with the results in terms of ToF spectra and number of neutrons with a Varian Clinac iX are presented.
Calibration and intercomparison of neutron moderation spectrometers
International Nuclear Information System (INIS)
Results have been reported of comparative measurements of neutron fields from bare PuBe and Cf sources using multisphere (Bonner) spectrometers. The experiments were carried out by the Institute of Biophysics and Nuclear Medicine at Charles University in Prague and the National Board for Atomic Safety and Radiation Protection in Berlin. Both sides agreed upon uniform measuring conditions and calibration factors thus rendering possible the comparability of the dosimetric parameters which have been determined and verified, respectively, to an accuracy of ± 10%. 20 refs., 10 tabs., 2 figs. (author)
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......, 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....... 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...
A new method of researching fermion tunneling from the Vaidya-Bonner de Sitter black hole
Institute of Scientific and Technical Information of China (English)
Lin Kai; Yang Shu-Zheng
2009-01-01
Using the general tortoise coordinate transformation, we research the fermion tunneling of the Vaidya-Bonner de Sitter black hole via a semi-classical method and finally obtain the right surface gravity, Hawking temperature and tunneling rate near the event horizon and cosmical horizon.
A new method of researching fermion tunneling from the Vaidya–Bonner de Sitter black hole
International Nuclear Information System (INIS)
Using the general tortoise coordinate transformation, we research the fermion tunneling of the Vaidya–Bonner de Sitter black hole via a semi-classical method and finally obtain the right surface gravity, Hawking temperature and tunneling rate near the event horizon and cosmical horizon
Development of the nSpect portable neutron spectrometer
International Nuclear Information System (INIS)
Portable instruments are particularly useful when a neutron spectrum is required for an area with limited space and accessibility. Portable instruments also offer a practical, cost-effective means by which areas that require infrequent surveying can be examined. This paper discusses the design and development of nSpect, a new, truly portable, neutron spectrometer. The nSpect spectrometer is a direct replacement for existing transportable neutron spectrometers, designed to perform equivalently or better. However, the use of bespoke electronic circuits and a more compact and lightweight design have reduced the typical mass of these instruments to approximately 15 kg. This weight falls within manual handling guidelines and makes nSpect truly portable. The nSpect spectrometer is fully-contained within two units, a sensor probe and a remote operator console. This allows the operator to be up to 40 m from the field while being much easier to carry than, for example, the significant bulk of a Bonner sphere set or less portable spectrometers. nSpect employs a variety of detectors which define six overlapping energy ranges to give nSpect an overall energy range from the thermal region (0.025 eV) to 10 MeV. Two BF3 proportional counters are used to assess the neutron flux at thermal and epi-thermal energies. A heavy metal sleeve has been used around one of the BF3 detectors in order to shield it from the thermal component of the flux. Hydrogen-filled proportional counters, with filling pressures of 1, 3 and 10 atm., have been used for the 50 keV - 1.4 MeV energy range. These spherical proportional counters, named SP10, have been adapted from the Centronic Ltd. SP9-type detector specifically for this project. A new approach to the energy calibration of spherical proportional counters has been developed and applied to the nSpect SP10 detectors. A small liquid scintillator cell, filled with EJ-301, is used for the 1 - 10 MeV energy range. High-speed digital electronics have
Measuring neutron spectra in radiotherapy using the nested neutron spectrometer
Energy Technology Data Exchange (ETDEWEB)
Maglieri, Robert, E-mail: robert.maglieri@mail.mcgill.ca; Evans, Michael; Seuntjens, Jan; Kildea, John [Medical Physics Unit, McGill University, Montreal, Quebec H4A 3J1 (Canada); Licea, Angel [Canadian Nuclear Safety Commission, Ottawa, Ontario K1P 5S9 (Canada)
2015-11-15
Purpose: Out-of-field neutron doses resulting from photonuclear interactions in the head of a linear accelerator pose an iatrogenic risk to patients and an occupational risk to personnel during radiotherapy. To quantify neutron production, in-room measurements have traditionally been carried out using Bonner sphere systems (BSS) with activation foils and TLDs. In this work, a recently developed active detector, the nested neutron spectrometer (NNS), was tested in radiotherapy bunkers. Methods: The NNS is designed for easy handling and is more practical than the traditional BSS. Operated in current-mode, the problem of pulse pileup due to high dose-rates is overcome by measuring current, similar to an ionization chamber. In a bunker housing a Varian Clinac 21EX, the performance of the NNS was evaluated in terms of reproducibility, linearity, and dose-rate effects. Using a custom maximum-likelihood expectation–maximization algorithm, measured neutron spectra at various locations inside the bunker were then compared to Monte Carlo simulations of an identical setup. In terms of dose, neutron ambient dose equivalents were calculated from the measured spectra and compared to bubble detector neutron dose equivalent measurements. Results: The NNS-measured spectra for neutrons at various locations in a treatment room were found to be consistent with expectations for both relative shape and absolute magnitude. Neutron fluence-rate decreased with distance from the source and the shape of the spectrum changed from a dominant fast neutron peak near the Linac head to a dominant thermal neutron peak in the moderating conditions of the maze. Monte Carlo data and NNS-measured spectra agreed within 30% at all locations except in the maze where the deviation was a maximum of 40%. Neutron ambient dose equivalents calculated from the authors’ measured spectra were consistent (one standard deviation) with bubble detector measurements in the treatment room. Conclusions: The NNS may
International Nuclear Information System (INIS)
Chopper spectrometers are devices which measure the dynamics of condensed systems expressed in terms of the scattering function. The scattering function depends on the energy and momentum transfers which are related to the initial and final neutron wave vectors. The resolution of the instrument is limited by the time-of-flight measurements on the scattered beam but the wide range of accessible energy and momentum transfers make chopper spectrometers popular. Several examples of experiments using chopper spectrometers are presented
Hawking radiation of the Vaidya-Bonner-de Sitter black hole
Energy Technology Data Exchange (ETDEWEB)
Chen Deyou; Yang Shuzheng [Institute of Theoretical Physics, China West Normal University, Nanchong, Sichuan 637002 (China)
2007-08-15
Considering the unfixed background space-time and the self-gravitational interaction, we view the Hawking radiation of the Vaidya-Bonner- de Sitter black hole by the Hamilton-Jacobi method and the radial geodesic method. The result shows the tunneling rate is related not only to the change of Bekenstein-Hawking entropy but also to the integral of the black hole mass and charge, which does not satisfy the unitary theory and is not in accordance with the known result.
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.).
Institute of Scientific and Technical Information of China (English)
杨波
2007-01-01
采用新的Tortoise坐标变换,将Vaidya-Bonner-de Sitter黑洞中的Klein-Gordon方程,在黑洞视界面附近化成典型的波动方程,得到在视界面附近Hawking辐射温度,导出了Hawking热辐射谱.
Institute of Scientific and Technical Information of China (English)
邓娟; 蒋青权; 冯中文; 李国平
2012-01-01
采用一种新的广义乌龟坐标变换对Vaidya-Bonner-de Sitter黑洞的熵进行研究,同时对其在旧乌龟坐标变换下的情况也做了对比分析.其结果表明两种情况下熵的形式相近,但是,新的广义乌龟坐标的结果对Vaidya-Bonner-de Sitter黑洞的熵做了相应的修正,新的乌龟坐标变换显得更加合理.%The principal focus of this paper is to study the entropy of Vaidya-Bonner-de Sitter black hole under a new general tortoise coordinate transformation, and then, to make the contrast and analysis of it with the old tortoise coordinates. It is found that the entropies obtained from both the new and old tortoise coordinate transformations are close to each other. The new general tortoise coordinate transformation makes the corresponding modification for the entropy of Vaidya-Bonner-de Sitter black hole and appears to be more reasonable.
Institute of Scientific and Technical Information of China (English)
孙鸣超
2005-01-01
在Tortoise坐标系中,利用brick-wall模型研究了电磁场对Vaidya-Bonner-de Sitter黑洞熵的量子修正. 当黑洞事件视界不随超前时间变化时,结果与Reissner-Nordstrm-de Sitter黑洞的量子熵完全相同.
Chaney, A.; Lu, Lei; Stern, A.
2015-09-01
We show that fuzzy spheres are solutions of Lorentzian Ishibashi-Kawai-Kitazawa-Tsuchiya-type matrix models. The solutions serve as toy models of closed noncommutative cosmologies where big bang/crunch singularities appear only after taking the commutative limit. The commutative limit of these solutions corresponds to a sphere embedded in Minkowski space. This "sphere" has several novel features. The induced metric does not agree with the standard metric on the sphere, and, moreover, it does not have a fixed signature. The curvature computed from the induced metric is not constant, has singularities at fixed latitudes (not corresponding to the poles) and is negative. Perturbations are made about the solutions, and are shown to yield a scalar field theory on the sphere in the commutative limit. The scalar field can become tachyonic for a range of the parameters of the theory.
Song, F.; Toksoz, M. N.
2012-12-01
Over the last decade, hydraulic fracturing has become one important key enabling technique in the development of unconventional oil and gas reservoirs. Microseismic monitoring has proved to be an effective diagnostic tool to image complex fracturing and to understand fracture growth. The initial uptake of this geophysical technology has been focused on fast and accurate microearthquake locations. In addition to locations, microearthquake source mechanisms, represented by the complete moment tensors, reveal important information on geomechanical understanding of hydrofrac growth and have profound implications on fracturing design. The retrieval of complete moment tensors has been hindered by several factors including limited geophone azimuthal coverage, relatively poor data quality (due to small event magnitudes and high borehole noise) and velocity model uncertainty. In this paper, the complete microseismic moment tensors have been inverted using full waveforms. We use the waveforms to obtain an accurate velocity structure. The unconstrained inversion using two-well data and constrained inversion with one-well data have been conducted on Barnett shale and Bonner sand, respectively. Different fracture growth patterns are seen in these two datasets. The source mechanisms show mixed failure modes in the complex fracture network from the Barnett shale. In the Bonner sands, a planar fracture grows mostly by shear failure at tip characterized by a double couple mechanism. The results may be explained by different reservoir conditions, including the geomechanical properties of the formations. Correctly inverted microearthquake source mechanisms help better understand both the hydraulic fracturing and the underlying reservoir, and aid the development of sophisticated horizontal well completions.
Waechter, David A.; Wolf, Michael A.; Umbarger, C. John
1985-01-01
A hand-holdable, battery-operated, microprocessor-based spectrometer gun includes a low-power matrix display and sufficient memory to permit both real-time observation and extended analysis of detected radiation pulses. Universality of the incorporated signal processing circuitry permits operation with various detectors having differing pulse detection and sensitivity parameters.
International Nuclear Information System (INIS)
A hand-holdable, battery-operated, microprocessor-based spectrometer gun includes a low-power matrix display and sufficient memory to permit both real-time observation and extended analysis of detected radiation pulses. Universality of the incorporated signal processing circuitry permits operation with various detectors having differing pulse detection and sensitivity parameters
International Nuclear Information System (INIS)
The expedition carried out in March, 2008 to Lake Baikal became an important stage in the development of the SPHERE experiment. During the expedition the SPHERE-2 installation was hoisted, for the first time, on a tethered balloon, APA, to a height of 700 m over the lake surface covered with ice and snow. A series of test measurements were made. Preliminary results of the data processing are presented. The next plan of the SPHERE experiment is to begin a set of statistics for constructing the CR spectrum in the energy range 1016-1018 eV.
Institute of Scientific and Technical Information of China (English)
孙鸣超
2003-01-01
在Tortoise坐标系中,利用Brick-Wall模型研究中微子场和标量场对Vaidya-Bonner-de Sitter黑洞熵的量子修正.当黑洞事件视界不随超前时间变化时,结果与Reissner-Nordstrom-de Sitter黑洞的量子熵完全相同.
Klotsa, Daphne; Hill, Richard J A; Bowley, Roger M; Swift, Michael R
2015-01-01
We describe experiments and simulations demonstrating the propulsion of a neutrally-buoyant swimmer that consists of a pair of spheres attached by a spring, placed in a vibrating fluid. The vibration of the fluid induces relative motion of the spheres which, for sufficiently large amplitudes, can lead to motion of the center of mass of the two spheres. We find that the swimming speed obtained from both experiment and simulation agree and collapse onto a single curve if plotted as a function of the streaming Reynolds number, suggesting that the propulsion is related to streaming flows. There appears to be a critical onset value of the streaming Reynolds number for swimming to occur. The mechanism for swimming is traced to a jet of fluid generated by the relative motion of the spheres.
International Nuclear Information System (INIS)
The recent advances in Moessbauer spectrometers, their parameters and electronic circuits are reviewed. The transfer functions of two mathematical models of electromechanical transducers (with discrete and continuously distributed parameters) are given. The problems of drive and pick-up parts optimisation are discussed. The electronic circuits for reference triangle wave generators with reduced nonlinearity are described. The influence of the positive and negative corrections of the Moessbauer spectrometer feedback loop on the error-signal is discussed. A flow chart for adaptive minimization of the error-signal is presented. In addition a special drive system using piezoelements with an appropriate digital sinusoidal generator is also included. A flow chart of the system for data acquisition is shown. (author)
International Nuclear Information System (INIS)
The recent advances in Moessbauer spectrometers, their parameters and electronic circuits are reviewed. The transfer functions of two mathematical models of electromechanical transducers (with discrete and continuously distributed parameters) are given. The problem of optimization of the drive and pick-up parts is discussed. The electronic circuits for reference triangle wave generators with reduced nonlinearity are described. A Moessbauer spectrometer with both positive and negative corrections in the feedback loop is described. The influence of these corrections on the error-signal is discussed. A flow chart for adaptive minimization of the error-signal is presented. In addition a special drive system using piezo elements with an appropriate digital sinusoidal generator is also included. A flow chart of the system using PC for data accumulation is shown. (author)
International Nuclear Information System (INIS)
Measurements made using electron spectrometers can lead to the determination of all the parameters that fully characterize the photoionization process. The measurements fall into three categories: the angular independent flux of the photoelectrons which leads to the partial cross section, the angular distribution of the photoelectrons, and the spin of the photoelectrons. The majority of this paper is concerned with electron energy analyzers which can be used to measure both the partial cross section and the angular distribution
In-Field Absolute Calibration of Ground and Airborne VIS-NIR-SWIR Hyperspectral Point Spectrometers
Directory of Open Access Journals (Sweden)
Offer Rozenstein
2014-01-01
Full Text Available Spectrometer calibration and measurements of spectral radiance are often required when performing ground, aerial, and space measurements. While calibrating a spectrometer in the field using an integrating sphere is practically unachievable, calibration against a quartz halogen (QH lamp is a quite easy and feasible option. We describe a calibration protocol whereby a professional QH lamp, operating with a stabilized current source, is first calibrated in the laboratory against a US National Institute of Standards and Technology (NIST traceable integrating sphere and, then, used for the field calibration of a spectrometer before a ground or airborne campaign. Another advantage of the lamp over the integrating sphere is its ability to create a continuous calibration curve at the spectrometer resolution, while the integrating sphere is calibrated only for a few discrete wavelengths. A calibrated lamp could also be used for a secondary continuous calibration of an un-calibrated integrating sphere.
Neutron spectrometry and dosimetry in the environment and at workplaces
International Nuclear Information System (INIS)
Results obtained in diverse environments (including workplaces) using both spectrometric and dosimetric instrumentation were compared. The following topics are included: PTB Bonner sphere spectrometers; natural cosmic ray-induced neutron background; neutron fields at the Dukovany nuclear power plant (Czech Republic); neutron fields at the isochronous cyclotron of the German Cancer Research center in Heidelberg; and accuracy of the integral results obtained with Bonner spheres. (P.A.)
Synthesis of corrected multi-wavelength spectrometers for atmospheric trace gases
Institute of Scientific and Technical Information of China (English)
Hikmat H.Asadov; Islam M.Mirzabalayev; Davud Z.Aliyev; Javid A.Agayev; Sima R.Azimova; Nabi A.Nabiyev; Sevinj N.Abdullayeva
2009-01-01
The method for synthesis of corrected three-wavelengths spectrometers for trace gas components of atmo sphere on the basis of development of mathematical model has been suggested.The classification table for possible structures of corrected spectrometers is considered.The synthesis allows to reveal some new variants for development of three-wavelength spectrometers for trace gas components of atmosphere.For experimental checkup of achieved theoretical results,a laboratory pattern of three-wavelength spectrometer is developed and tested.
Scattering by a nihility sphere
Lakhtakia, A
2006-01-01
On interrogation by a plane wave, the back-scattering efficiency of a nihility sphere is identically zero, and its extinction and forward-scattering efficiencies are higher than those of a perfectly conducting sphere.
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.
Algebraic properties of Bier spheres
Directory of Open Access Journals (Sweden)
Inga Heudtlass
2012-05-01
Full Text Available We give a classification of flag Bier spheres, as well as descriptions of the first and second Betti numbers of general Bier spheres. Additionally, we compute the Betti numbers for a specific class of Bier spheres, constructed from skeletons of a full simplex.
Entanglement entropy for odd spheres
Dowker, J S
2010-01-01
It is shown, non--rigorously, that the effective action on a Z_q factored odd spheres (lune) has a vanishing derivative at q=1. This leaves the effective action on the ordinary odd d-sphere as (minus) the value of the entanglement entropy associated with a (d-2)-sphere. Some numbers are given.
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.
Peternell, Martin; Sendra, Juana
2011-01-01
The conchoid of a surface $F$ with respect to given fixed point $O$ is roughly speaking the surface obtained by increasing the radius function with respect to $O$ by a constant. This paper studies {\\it conchoid surfaces of spheres} and shows that these surfaces admit rational parameterizations. Explicit parameterizations of these surfaces are constructed using the relations to pencils of quadrics in $\\R^3$ and $\\R^4$. Moreover we point to remarkable geometric properties of these surfaces and their construction.
Godsil, C. D.; Zaks, J.
2012-01-01
Let $G$ be the graph with the points of the unit sphere in $\\mathbb{R}^3$ as its vertices, by defining two unit vectors to be adjacent if they are orthogonal as vectors. We present a proof, based on work of Hales and Straus chromatic number of this graph is four. We also prove that the subgraph of G induced by the unit vectors with rational coordinates is 3-colourable.
Berenstein, David; Lashof-Regas, Robin
2015-01-01
We construct various exact analytical solutions of the $SO(3)$ BMN matrix model that correspond to rotating fuzzy spheres and rotating fuzzy tori.These are also solutions of Yang Mills theory compactified on a sphere times time and they are also translationally invariant solutions of the $\\mathcal{N} = 1^*$ field theory with a non-trivial charge density. The solutions we construct have a $\\mathbb{Z}_N$ symmetry, where $N$ is the rank of the matrices. After an appropriate ansatz, we reduce the problem to solving a set of polynomial equations in $2N$ real variables. These equations have a discrete set of solutions for each value of the angular momentum. We study the phase structure of the solutions for various values of $N$. Also the continuum limit where $N\\to \\infty$, where the problem reduces to finding periodic solutions of a set of coupled differential equations. We also study the topology change transition from the sphere to the torus.
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
Falling-sphere radioactive viscometry
International Nuclear Information System (INIS)
In this work the falling sphere viscometric method was studies experimentally using a sphere tagged with 198Au radiosotopo, the objective being the demosntration of the advantages of this technique in relation to the traditional method. The utilisation of the falling radioactive sphere permits the point-point monitoring of sphere position as a function of count rate. The fall tube wall and end effects were determined by this technique. Tests were performed with spheres of different diameters in four tubes. The application of this technique demosntrated the wall and end effects in sphere speed. The case of sphere fall in the steady slow regime allowed the determination of the terminal velocity, showing the increase of botton end effect as the sphere approaches the tube base. In the case the transient slow regime, the sphere was initially in a state of respose near the top surface. The data obtained show the influence of the free surface and wall on the sphere acceleration. These experimental data were applied to the Basset equation on order to verify the behaviour of the terms in this equation. (author)
Development of Miniature Spectrometers
Institute of Scientific and Technical Information of China (English)
ZHANG Zhi-guo
2007-01-01
Spectrometer is an essential and necessary optical element used for measuring the chemical components and content of the matter.The development of miniature spectrometers can be traced back to 1980s.The development state and different manufacturing methods of micro-spectrometers are presented.Finally,we analyze the miniaturization trend of spectrometers.Some groundwork for the scientific research is offered by introducing micro-spectrometers development.
Plaquettes, Spheres, and Entanglement
Grimmett, Geoffrey R
2010-01-01
The high-density plaquette percolation model in d dimensions contains a surface that is homeomorphic to the (d-1)-sphere and encloses the origin. This is proved by a path-counting argument in a dual model. When d=3, this permits an improved lower bound on the critical point p_e of entanglement percolation, namely p_e >= \\mu^-2 where \\mu is the connective constant for self-avoiding walks on Z^3. Furthermore, when the edge density p is below this bound, the radius of the entanglement cluster containing the origin has an exponentially decaying tail.
Generalized Sphere Packing Bound
Fazeli, Arman; Vardy, Alexander; Yaakobi, Eitan
2014-01-01
Kulkarni and Kiyavash recently introduced a new method to establish upper bounds on the size of deletion-correcting codes. This method is based upon tools from hypergraph theory. The deletion channel is represented by a hypergraph whose edges are the deletion balls (or spheres), so that a deletion-correcting code becomes a matching in this hypergraph. Consequently, a bound on the size of such a code can be obtained from bounds on the matching number of a hypergraph. Classical results in hyper...
Dowker, J S
2012-01-01
I give some scalar field theory calculations on a d-dimensional lune of arbitrary angle, evaluating, numerically, the effective action which is expressed as a simple quadrature, for conformal coupling. Using this, the entanglement and Renyi entropies are computed. Massive fields are also considered and a renormalisation to make the (one-loop) effective action vanish for infinite mass is suggested and used, not entirely successfully. However a universal coefficient is derived from the large mass expansion. For the round sphere, I show how to convert the quadrature form of the conformal Laplacian determinant into the more usual sum of Riemann zeta functions (and log2).
Regular Totally Separable Sphere Packings
Reid, Samuel
2015-01-01
The topic of totally separable sphere packings is surveyed with a focus on regular constructions, uniform tilings, and contact number problems. An enumeration of all regular totally separable sphere packings in $\\mathbb{R}^2$, $\\mathbb{R}^3$, and $\\mathbb{R}^4$ which are based on convex uniform tessellations, honeycombs, and tetracombs, respectively, is presented, as well as a construction of a family of regular totally separable sphere packings in $\\mathbb{R}^d$ that is not based on a convex...
Properties of lithium orthosilicate spheres
International Nuclear Information System (INIS)
Lithium ceramic spheres have been proposed as a tritium breeding material for a fusion reactor blanket. Spheres fabricated by Schott, Mainz show a glass-like structure in light and scanning electron microscopy. A crystalline structure, however, was detected by X-ray diffraction. Part of the spheres were annealed at 10000C for 2 h to heal microcracks and to relieve internal stress. After annealing a grain structure was found by microscopy with grains of 10-30 μm grain size. When stored in air the spheres took up moisture. After some days the water content yielded 2-3 mol%. A thermo-mechanical test was conducted with the spheres by cycling between 60 and 6000C in a stainless steel capsule which simulated the pressure load during thermal cycling of the fusion reactor blanket. Examination of the spheres after 10 cycles showed that 11% of as-fabricated spheres were broken. The amount of broken spheres which had been annealed was only 2%. It is assumed that healing of microcracks and relieve of internal stress improves the behavior of the spheres. (orig.)
Panoramic stereo sphere vision
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.
Sphere Recognition: Heuristics and Examples
Joswig, Michael; Lutz, Frank H.; Tsuruga, Mimi
2014-01-01
Heuristic techniques for recognizing PL spheres using the topological software polymake are presented. These methods have been successful very often despite sphere recognition being known to be hard (for dimensions $d \\ge 3$) or even undecidable (for $d \\ge 5$). A deeper look into the simplicial complexes for which the heuristics failed uncovered a trove of examples having interesting topological and combinatorial properties.
Isentropic Spheres in General Relativity
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".
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......), and subjectivity (agency). This changed the public sphere into an assemblage consisting of both human and non-human actors interactingin a highly dynamic, networked environment. This paper proposes a framework for considering this new materiality in the field of the public sphere: the assemblage and complexity...
Simple manipulator for rotating spheres
International Nuclear Information System (INIS)
We describe a simple device for rapidly rotating a small sphere to any orientation for inspection of the surface. The ball is held between two small, flat surfaces and rolls as the surfaces are moved differentially parallel to one another
Data compression on the sphere
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...
Dyson Spheres around White Dwarfs
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.
Experimental verification of the JRR-4 BNCT facility. Pt. 1
International Nuclear Information System (INIS)
The report is structured as follows: (1) Introduction (JAERI facility; Modes, parameters); (2) Experimental methods (Activation foils: activity measurements, spectrum adjustment; Bonner spheres spectrometer; Al-P glass TLD; Semiconductor detector; Si diode for fast neutron kerma determination); (3) Experimental set-up (Free beam measurements: neutron spectrum measurement, photon dose and fast neutron kerma measurement, beam profile measurement, BSS measurement; Phantom measurements: neutron dose depth measurement, photon dose and fast neutron kerma depth profiles, on-line thermal neutron measurement in water phantom, on-line thermal neutron measurement in cylindrical water phantom); 4. Si-Li detector dead time and effectiveness; and (5) The Bonner sphere spectrometer responses. (P.A.)
Economics and the Public Sphere
Reinert, Erik S.
2012-01-01
This paper identifies four different periods (1848, 1890s - partly also 1930s - and neoliberalism today) where the same tendencies recur: a Rise of Academic Monoculture (of esoteric knowledge), Refeudalization (tendencies towards a plutocracy), Crisis and Renewal. These sequences and their recurrence define the changing relationship between economics and the public sphere, and it is only through activities in the public sphere that any renewal will take place.
Isentropic Spheres in General Relativity
Humi, Mayer; Roumas, John
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 she...
McEwen, J D; Lasenby, A N
2006-01-01
We derive optimal filters on the sphere in the context of detecting compact objects embedded in a stochastic background process. The matched filter and the scale adaptive filter are derived on the sphere in the most general setting, allowing for directional template profiles and filters. The performance and relative merits of the two optimal filters are discussed. The application of optimal filter theory on the sphere to the detection of compact objects is demonstrated on simulated mock data. A naive detection strategy is adopted, with an initial aim of illustrating the application of the new optimal filters derived on the sphere. Nevertheless, this simple object detection strategy is demonstrated to perform well, even a low signal-to-noise ratio. Code written to compute optimal filters on the sphere (S2FIL), to perform fast directional filtering on the sphere (FastCSWT) and to construct the simulated mock data (COMB) are all made publicly available. (Accompanying code will be made publicly available on publi...
IRAS-based whole-sky upper limit on Dyson Spheres
Energy Technology Data Exchange (ETDEWEB)
Carrigan, Richard A., Jr.; /Fermilab
2008-09-01
A Dyson Sphere is a hypothetical construct of a star purposely cloaked by a thick swarm of broken-up planetary material to better utilize all of the stellar energy. A clean Dyson Sphere identification would give a significant signature for intelligence at work. A search for Dyson Spheres has been carried out using the 250,000 source database of the IRAS infrared satellite which covered 96% of the sky. The search has used the Calgary data collection of the IRAS Low Resolution Spectrometer (LRS) to look for fits to blackbody spectra. Searches have been conducted for both pure (fully cloaked) and partial Dyson Spheres in the blackbody temperature region 100 {le} T {le} 600 K. Other stellar signatures that resemble a Dyson Sphere are reviewed. When these signatures are used to eliminate sources that mimic Dyson Spheres very few candidates remain and even these are ambiguous. Upper limits are presented for both pure and partial Dyson Spheres. The sensitivity of the LRS was enough to find solar-sized Dyson Spheres out to 300 pc, a reach that encompasses a million solar-type stars.
Non-equilibrium Casimir forces: Spheres and sphere-plate
Krüger, Matthias; Bimonte, Giuseppe; Kardar, Mehran
2011-01-01
We discuss non-equilibrium extensions of the Casimir force (due to electromagnetic fluctuations), where the objects as well as the environment are held at different temperatures. While the formalism we develop is quite general, we focus on a sphere in front of a plate, as well as two spheres, when the radius is small compared to separation and thermal wavelengths. In this limit the forces can be expressed analytically in terms of the lowest order multipoles, and corroborated with results obtained by diluting parallel plates of vanishing thickness. Non-equilibrium forces are generally stronger than their equilibrium counterpart, and may oscillate with separation (at a scale set by material resonances). For both geometries we obtain stable points of zero net force, while two spheres may have equal forces in magnitude and direction resulting in a self-propelling state.
Unveiling small sphere's scattering behavior
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.
Troubleshooting vSphere storage
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
International Nuclear Information System (INIS)
The SAGE spectrometer has been constructed for in-beam nuclear structure studies. SAGE combines a Ge-detector array and an electron spectrometer for detection of γ-rays and internal conversion electrons, respectively, and allows simultaneous observation of both electrons and γ-rays emitted from excited nuclei. SAGE is set up in the Accelerator Laboratory of the University of Jyvaeskylae and works in conjunction with the RITU gas-filled recoil separator and the GREAT focal-plane spectrometer allowing the use of the recoil-decay tagging method. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Pakarinen, J.; Papadakis, P. [University of Liverpool, Department of Physics, Oliver Lodge Laboratory, Liverpool (United Kingdom); University of Jyvaeskylae, Department of Physics, Jyvaeskylae (Finland); Sorri, J.; Greenlees, P.T.; Jones, P.; Julin, R.; Konki, J.; Rahkila, P.; Sandzelius, M. [University of Jyvaeskylae, Department of Physics, Jyvaeskylae (Finland); Herzberg, R.D.; Butler, P.A.; Cox, D.M.; Cresswell, J.R.; Mistry, A.; Page, R.D.; Parr, E.; Sampson, J.; Seddon, D.A.; Thornhill, J.; Wells, D. [University of Liverpool, Department of Physics, Oliver Lodge Laboratory, Liverpool (United Kingdom); Coleman-Smith, P.J.; Lazarus, I.H.; Letts, S.C.; Pucknell, V.F.E.; Simpson, J. [STFC Daresbury Laboratory, Warrington (United Kingdom)
2014-03-15
The SAGE spectrometer has been constructed for in-beam nuclear structure studies. SAGE combines a Ge-detector array and an electron spectrometer for detection of γ-rays and internal conversion electrons, respectively, and allows simultaneous observation of both electrons and γ-rays emitted from excited nuclei. SAGE is set up in the Accelerator Laboratory of the University of Jyvaeskylae and works in conjunction with the RITU gas-filled recoil separator and the GREAT focal-plane spectrometer allowing the use of the recoil-decay tagging method. (orig.)
Laflamme-Sanders, Alexandra; Zhu, Mu
2008-11-01
LAGO is an efficient kernel algorithm designed specifically for the rare target detection problem. However, unlike other kernel algorithms, LAGO cannot be easily used with many domain-specific kernels. We solve this problem by first providing a unified framework for LAGO and clarifying its basic principle, and then applying that principle on the unit sphere instead of in the Euclidean space. PMID:18775643
Boulatov, D. V.
1993-01-01
We give the formula for a simple Wilson loop on a sphere which is valid for an arbitrary QCD$_2$ saddle-point $\\rho(x)$: \\mbox{$W(A_1,A_2)=\\oint \\frac{dx}{2\\pi i} \\exp(\\int dy \\frac{\\rho(y)}{y-x}+A_2x)$}. The strong-coupling-phase solution is investigated.
Schleimer, Saul
2004-01-01
We prove that the three-sphere recognition problem lies in the complexity class NP. Our work relies on Thompson's original proof that the problem is decidable [Math. Res. Let., 1994], Casson's version of her algorithm, and recent results of Agol, Hass, and Thurston [ArXiv, 2002].
Kinetic theory of hard spheres
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
Energy Technology Data Exchange (ETDEWEB)
Anon.
2009-11-15
In the ''Bonner Bogen'' construction project, the focus was on resources-saving technology and maximum user comfort, resulting in an integrated planning and implementation process. According to the investor, BonnVisio, the technical infrastructure and energy center of the building - based on groundwater geothermal energy with aquifer storage - is unique in Germany and Europe in terms of size, mode of operation, and efficiency. (orig.)
Digital positron annihilation spectrometer
International Nuclear Information System (INIS)
With the high speed development of digital signal process, the technique of the digitization and processing of signals was applied in the domain of a broad class of nuclear technique. The development of digital positron lifetime spectrometer (DPLS) is more promising than the conventional positron lifetime spectrometer equipped with nuclear instrument modules. And digital lifetime spectrometer has many advantages, such as low noise, long term stability, flexible online or offline digital processing, simple setup, low expense, easy to setting, and more physical information. Digital constant fraction discrimination is for timing. And a new method of optimizing energy windows setting for digital positron lifetime spectrometer is also developed employing the simulated annealing for the convenient use. The time resolution is 220ps and the count rate is 200cps. (authors)
Evaluation of response matrix of a multisphere neutron spectrometer with water moderator
Indian Academy of Sciences (India)
Rahim Khabaz; Hashem Miri Hakimabad
2011-10-01
Neutron energy responses of water sphere spectrometers (WSS) to 30 MeV have been calculated by means of Monte Carlo calculations, using the computer code MCNP4C with ENDF/B-VI.0 neutron cross-section. The calculations have been performed for 3He detector (typical SP9) placed inside 2, 3, 5, 8, 12 and 18-inch diameter moderating spheres composed of water in aluminum shell. These simulations included a detailed description of the geometry of the system. The newly calculated responses have been compared to polyethylene sphere responses.
Eddy currents in a conducting sphere
Bergman, John; Hestenes, David
1986-01-01
This report analyzes the eddy current induced in a solid conducting sphere by a sinusoidal current in a circular loop. Analytical expressions for the eddy currents are derived as a power series in the vectorial displacement of the center of the sphere from the axis of the loop. These are used for first order calculations of the power dissipated in the sphere and the force and torque exerted on the sphere by the electromagnetic field of the loop.
Minimality of Symplectic Fiber Sums along Spheres
Dorfmeister, Josef G
2010-01-01
In this note we complete the discussion of minimality of symplectic fiber sums. We find, that for fiber sums along spheres the minimality of the sum is determined by the cases discussed by M. Usher and one additional case: If the sum is the result of the rational blow-down of a symplectic -4-sphere in X, then it is non-minimal if X contains a certain configuration of exceptional spheres in relation to this -4-sphere.
Coating a Sphere With Evaporated Metal
Strayer, D. M.; Jackson, H. W.; Gatewood, J. R.
1986-01-01
In vacuum coating apparatus, metal evaporated onto sphere from small source located some distance away. Sphere held in path of metal vapor while rotated about axis that rocks back and forth. One tilting motion particularly easy to produce is sinusoidal rocking with frequency much lower than rotational frequency. Apparatus developed for coating single-crystal sapphire spheres with niobium.
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......, the allocation of (or selection into) learning places, teaching–learning practices, teachers’ treatment of students, and student evaluations of grade distribution. We discuss the literature on the beliefs by students and teachers about the just distribution of educational goods in these five domains......, and on the practices used in the actual allocation of these goods. In line with normative ‘spheres of justice’ arguments in social theory, we conclude that the ideals of social justice within schools vary strongly according to the particular resource to be distributed. Moreover, these ideals often do...
Sknepnek, Rastko; Henkes, Silke
2015-02-01
We show that coupling to curvature nontrivially affects collective motion in active systems, leading to motion patterns not observed in flat space. Using numerical simulations, we study a model of self-propelled particles with polar alignment and soft repulsion confined to move on the surface of a sphere. We observe a variety of motion patterns with the main hallmarks being polar vortex and circulating band states arising due to the incompatibility between spherical topology and uniform motion—a consequence of the "hairy ball" theorem. We provide a detailed analysis of density, velocity, pressure, and stress profiles in the circulating band state. In addition, we present analytical results for a simplified model of collective motion on the sphere showing that frustration due to curvature leads to stable elastic distortions storing energy in the band.
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.
Hard sphere packings within cylinders.
Fu, Lin; Steinhardt, William; Zhao, Hao; Socolar, Joshua E S; Charbonneau, Patrick
2016-02-23
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. PMID:26843132
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
Bedogni, R.; Buonomo, B.; Esposito, A.; Mazzitelli, G.; Foggetta, L.; Gomez Ros. J.M.; 10.1016/j.nima.2011.08.032
2011-01-01
science and studies of "single event effects". The intensity of the neutron beam obtainable with 510MeV electrons and its fluence energy distribution at a point of reference in the irradiation room were predicted by Monte Carlo simulations and experimentally determined with a Bonner Sphere Spectrometer (BSS). Due to the large photon contri...
Fusion breeder sphere - PAC blanket design
International Nuclear Information System (INIS)
There is a considerable world-wide effort directed toward the production of materials for fusion reactors. Many ceramic fabrication groups are working on making lithium ceramics in a variety of forms, to be incorporated into the tritium breeding blanket which will surround the fusion reactor. Current blanket designs include ceramic in either monolithic or packed sphere bed (sphere-pac) forms. The major thrust at AECL is the production of lithium aluminate spheres to be incorporated in a sphere-pac bed. Contemporary studies on breeder blanket design offer little insight into the requirements on the sizes of the spheres. This study examined the parameters which determine the properties of pressure drop and coolant requirements. It was determined that an optimised sphere-pac bed would be composed of two diameters of spheres: 75 weight % at 3 mm and 25 weight % at 0.3 mm
Generating perfect fluid spheres in general relativity
International Nuclear Information System (INIS)
Ever since Karl Schwarzschild's 1916 discovery of the spacetime geometry describing the interior of a particular idealized general relativistic star--a static spherically symmetric blob of fluid with position-independent density--the general relativity community has continued to devote considerable time and energy to understanding the general-relativistic static perfect fluid sphere. Over the last 90 years a tangle of specific perfect fluid spheres has been discovered, with most of these specific examples seemingly independent from each other. To bring some order to this collection, in this article we develop several new transformation theorems that map perfect fluid spheres into perfect fluid spheres. These transformation theorems sometimes lead to unexpected connections between previously known perfect fluid spheres, sometimes lead to new previously unknown perfect fluid spheres, and in general can be used to develop a systematic way of classifying the set of all perfect fluid spheres
International Nuclear Information System (INIS)
A magnetron mass-spectrometer characterized by increased sensitivity at low power is described. The mass-spectrometer contains ion source cylindrical analyzer located on its axis, ion collector and magnetic system. For decreasing consumed power the ion source is fixed at the end of the analyzer and it represents two coaXial cylinders located between plane electrodes, in one of which a ring slot takes place and the other one is connected with positive terminal of discharge voltage source. The magnetic system represents ring-form magnets fixed by similar poles to each other and separated by washers of magnetic-soft material, the washers being placed in the plane of the ion source. The analyzed ions in the described mass-spectrometer are obtained mainly at the expense of resonance recharge that increases accuracy of measurements due to decrease of fragment peak intensity
Teare, S. W.
2003-05-01
Many observatories and instrument builders are retrofitting visible and near-infrared spectrometers into their existing imaging cameras. Camera designs that reimage the focal plane and have the optical filters located in a pseudo collimated beam are ideal candidates for the addition of a spectrometer. One device commonly used as the dispersing element for such spectrometers is a grism. The traditional grism is constructed from a prism that has had a diffraction grating applied on one surface. The objective of such a design is to use the prism wedge angle to select the desired "in-line" or "zero-deviation" wavelength that passes through on axis. The grating on the surface of the prism provides much of the dispersion for the spectrometer. A grism can also be used in a "constant-dispersion" design which provides an almost linear spatial scale across the spectrum. In this paper we provide an overview of the development of a grism spectrometer for use in a near infrared camera and demonstrate that a compact grism spectrometer can be developed on a very modest budget that can be afforded at almost any facility. The grism design was prototyped using visible light and then a final device was constructed which provides partial coverage in the near infrared I, J, H and K astronomical bands using the appropriate band pass filter for order sorting. The near infrared grism presented here provides a spectral resolution of about 650 and velocity resolution of about 450 km/s. The design of this grism relied on a computer code called Xspect, developed by the author, to determine the various critical parameters of the grism. This work was supported by a small equipment grant from NASA and administered by the AAS.
Ackerstaff, K.
1998-01-01
The HERMES experiment is collecting data on inclusive and semi-inclusive deep inelastic scattering of polarised positrons from polarised targets of H, D, and He. These data give information on the spin structure of the nucleon. This paper describes the forward angle spectrometer built for this purpose. The spectrometer includes numerous tracking chambers (micro-strip gas chambers, drift and proportional chambers) in front of and behind a 1.3 T.m magnetic field, as well as an extensive set of ...
Cyclotrons as mass spectrometers
Energy Technology Data Exchange (ETDEWEB)
Clark, D.J.
1984-04-01
The principles and design choices for cyclotrons as mass spectrometers are described. They are illustrated by examples of cyclotrons developed by various groups for this purpose. The use of present high energy cyclotrons for mass spectrometry is also described. 28 references, 12 figures.
1972-01-01
The Omega spectrometer which came into action during the year. An array of optical spark chambers can be seen withdrawn from the magnet aperture. In the 'igloo' above the magnet is located the Plumbicon camera system which collects information from the spark chambers.
DEFF Research Database (Denmark)
Chakrabarti, Maumita; Jakobsen, Michael Linde; Hanson, Steen Grüner
2015-01-01
A novel spectrometer concept is analyzed and experimentally verified. The method relies on probing the speckle displacement due to a change in the incident wavelength. A rough surface is illuminated at an oblique angle, and the peak position of the covariance between the speckle patterns observed...
Cyclotrons as mass spectrometers
International Nuclear Information System (INIS)
The principles and design choices for cyclotrons as mass spectrometers are described. They are illustrated by examples of cyclotrons developed by various groups for this purpose. The use of present high energy cyclotrons for mass spectrometry is also described. 28 references, 12 figures
Spherical electrostatic electron spectrometer
Energy Technology Data Exchange (ETDEWEB)
Yang, T.S.; Kolk, B.; Kachnowski, T.; Trooster, J.; Benczer-Koller, N. (Rutgers - the State Univ., New Brunswick, NJ (USA). Dept. of Physics)
1982-06-15
A high transmission, low energy spherical electrostatic electron spectrometer particularly suited to the geometry required for Moessbauer-conversion electron spectroscopy was built. A transmission of 13% at an energy resolution of 2% was obtained with an 0.5 cm diameter source of 13.6 keV electrons. Applications to the study of hyperfine interactions of surfaces and interfaces are discussed.
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
Duan, Zhipeng; He, Boshu; Duan, Yuanyuan
2015-07-01
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.
In Situ Mass Spectrometer Project
National Aeronautics and Space Administration — The In Situ Mass Spectrometer projects focuses on a specific subsystem to leverage advanced research for laser-based in situ mass spectrometer development...
Second-sphere complexes in analytical chemistry
International Nuclear Information System (INIS)
Literary data on the application in the modern analytical chemistry of outer-sphere complexes, forming from coordination-saturated inner-sphere complexes and ligands, cation particles or organic solvent molecules in the second sphere are summarised. It is shown, that the outer-sphere complexes peculiarities, involving in their relatively low stability and activation energy for the processes in the second sphere, together with their variety allows one to effectively use these complexes for separation, extraction and, especially, determination of inorganic and organic substances. Outer-sphere complexes are used to determine some transition metals, lanthanides, berillium, boron and some other elements. The improvement of sensitivity, selectivity and expressiveness of analytical determination, achieved here, is discussed
Sphere-Pac Evaluation for Transmutation
Energy Technology Data Exchange (ETDEWEB)
Icenhour, A.S.
2005-05-19
The U.S. Department of Energy Advanced Fuel Cycle Initiative (AFCI) is sponsoring a project at Oak Ridge National Laboratory with the objective of conducting the research and development necessary to evaluate the use of sphere-pac transmutation fuel. Sphere-pac fuels were studied extensively in the 1960s and 1970s. More recently, this fuel form is being studied internationally as a potential plutonium-burning fuel. For transmutation fuel, sphere-pac fuels have potential advantages over traditional pellet-type fuels. This report provides a review of development efforts related to the preparation of sphere-pac fuels and their irradiation tests. Based on the results of these tests, comparisons with pellet-type fuels are summarized, the advantages and disadvantages of using sphere-pac fuels are highlighted, and sphere-pac options for the AFCI are recommended. The Oak Ridge National Laboratory development activities are also outlined.
Synthesis and characterization of hydrocarbon sphere
International Nuclear Information System (INIS)
With glucose as starting material, hydrocarbon sphere which was rich in oxygen containing functional groups was synthesized by hydrothermal carbonization process, and characterized by SEM and FTIR techniques. The results show that the size and dispersion of carbon spheres depend on many factors, including the concentration of glucose, the reaction temperature and the adulterated organic monomer. The obtained hydrocarbon spheres contain rich functional groups which can greatly improve the hydrophilicity and chemical reactivity. (authors)
Counter public spheres and global modernity
Fenton, Natalie; Downey, John
2015-01-01
This article explores the concept of counter public spheres and their relationship to the dominant public sphere. We argue that counter public spheres are increasingly relevant due to particular social and political configurations that mark out a distinct stage of modernity. We suggest that this stage is characterised in particular by the intensification of globalisation, the rise of neo-liberalism and a decline of trust and social democracy resulting in instability in the dominant public sph...
Counter public spheres and global modernity:
Downey, John; Fenton, Natalie
2003-01-01
This article explores the concept of counter public spheres and their relationship to the dominant public sphere. We argue that counter public spheres are increasingly relevant due to particular social and political configurations that mark out a distinct stage of modernity. We suggest that this stage is characterised in particular by the intensification of globalisation, the rise of neo-liberalism and a decline of trust and social democracy resulting in instability in the dominant public sph...
The fuzzy sphere *-product and spin networks
International Nuclear Information System (INIS)
We analyze the expansion of the fuzzy sphere noncommutative product in powers of the noncommutativity parameter. To analyze this expansion we develop a graphical technique that uses spin networks. This technique is potentially interesting in its own right as introducing spin networks of Penrose into noncommutative geometry. Our analysis leads to a clarification of the link between the fuzzy sphere noncommutative product and the usual deformation quantization of the sphere in terms of the *-product
Simulation of the SAGE spectrometer
Cox, D. M.; Konki, J.; Greenlees, P. T.; Hauschild, K.; Herzberg, R.-D.; Pakarinen, J.; Papadakis, P.; Rahkila, P.; Sandzelius, M.; Sorri, J.
2015-06-01
The SAGE spectrometer combines a Ge-detector array with a Si detector to allow simultaneous detection of γ-rays and electrons. A comprehensive GEANT4 simulation package of the SAGE spectrometer has been developed with the ability to simulate the expected datasets based on user input files. The measured performance of the spectrometer is compared to the results obtained from the simulations.
Method for producing small hollow spheres
International Nuclear Information System (INIS)
A method is described for producing small hollow spheres of glass, metal or plastic, wherein the sphere material is mixed with or contains as part of the composition a blowing agent which decomposes at high temperature (T >approx. 6000C). As the temperature is quickly raised, the blowing agent decomposes and the resulting gas expands from within, thus forming a hollow sphere of controllable thickness. The thus produced hollow spheres (20 to 103μm) have a variety of application, and are particularly useful in the fabrication of targets for laser implosion such as neutron sources, laser fusion physics studies, and laser initiated fusion power plants
Hollow Spheres in Composite Materials and Metallic Hollow Sphere Composites (MHSC)
Baumeister, Erika; Molitor, Martin
The newly developed metallic hollow spheres are used in combination with a polymeric matrix for producing metallic hollow-sphere-composites (MSHC), which have been developed for mechanical engineering applications in the “InnoZellMet” project.
International Nuclear Information System (INIS)
The history and major accomplishments of the Effective Mass Spectrometer (EMS) are described. In the eight years since the EMS turned on, 21 experiments have been completed by groups from nine institutions in 32 months of operation. Over 400 million triggers have been recorded on magnetic tape, resulting in 29 journal publications to date. A list of experimental proposals for the EMS and a sampling of results are presented. 12 figures, 4 tables
Spherical electrostatic electron spectrometer
Yang, T.-S.; Kolk, B.; Kachnowski, T.; Trooster, J.; Benczer-Koller, N.
1982-06-01
A high transmission, low energy spherical electrostatic electron spectrometer particularly suited to the geometry required for Mössbauer-conversion electron spectroscopy was built. A transmission of 13% at an energy resolution of 2% was obtained with an 0.5 cm diameter source of 13.6 keV electrons. Applications to the study of hyperfine interactions of surfaces and interfaces are discussed.
ALICE photon spectrometer crystals
Maximilien Brice
2006-01-01
Members of the mechanical assembly team insert the last few crystals into the first module of ALICE's photon spectrometer. These crystals are made from lead-tungstate, a crystal as clear as glass but with nearly four times the density. When a high-energy particle passes through one of these crystals it will scintillate, emitting a flash of light allowing the energy of photons, electrons and positrons to be measured.
Magnetic spectrometer control system
International Nuclear Information System (INIS)
The design and implementation of a new computerized control system for the several devices of the magnetic spectrometer at TANDAR Laboratory is described. This system, as a main difference from the preexisting one, is compatible with almost any operating systems of wide spread use available in PC. This allows on-line measurement and control of all signals from any terminal of a computer network. (author)
The periodically oscillating plasma sphere
International Nuclear Information System (INIS)
A new method of operating an inertial electrostatic confinement (IEC) device is proposed, and its performance is evaluated. The scheme involved an oscillating thermal cloud of ions immersed in a bath of electrons that form a harmonic oscillator potential. The scheme is called the periodically oscillating plasma sphere, and it appears to solve many of the problems that may limit other IEC systems to low gain. A set of self-similar solutions to the ion fluid equations is presented, and plasma performance is evaluated. Results indicate that performance enhancement of gridded IEC systems such as the Los Alamos intense neutron source device is possible as well as high-performance operation for low-loss systems such as the Penning trap experiment. Finally, a conceptual idea for a massively modular Penning trap reactor is also presented
Mass spectrometers: instrumentation
Cooks, R. G.; Hoke, S. H., II; Morand, K. L.; Lammert, S. A.
1992-09-01
Developments in mass spectrometry instrumentation over the past three years are reviewed. The subject is characterized by an enormous diversity of designs, a high degree of competition between different laboratories working with either different or similar techniques and by extremely rapid progress in improving analytical performance. Instruments can be grouped into genealogical charts based on their physical and conceptual interrelationships. This is illustrated using mass analyzers of different types. The time course of development of particular instrumental concepts is illustrated in terms of the s-curves typical of cell growth. Examples are given of instruments which are at the exponential, linear and mature growth stages. The prime examples used are respectively: (i) hybrid instruments designed to study reactive collisions of ions with surfaces: (ii) the Paul ion trap; and (iii) the triple quadrupole mass spectrometer. In the area of ion/surface collisions, reactive collisions such as hydrogen radical abstraction from the surface by the impinging ion are studied. They are shown to depend upon the chemical nature of the surface through the use of experiments which utilize self-assembled monolayers as surfaces. The internal energy deposited during surface-induced dissociation upon collision with different surfaces in a BEEQ instrument is also discussed. Attention is also given to a second area of emerging instrumentation, namely technology which allows mass spectrometers to be used for on-line monitoring of fluid streams. A summary of recent improvements in the performance of the rapidly developing quadrupole ion trap instrument illustrates this stage of instrument development. Improvements in resolution and mass range and their application to the characterization of biomolecules are described. The interaction of theory with experiment is illustrated through the role of simulations of ion motion in the ion trap. It is emphasized that mature instruments play a
Habitable sphere and fine structure constant
Kozlovskii, Miroslaw P; Kozlowski, Miroslaw; Marciak-Kozlowska, Janina
2005-01-01
Future space missions, TPF and Darwin will focus on searches of signatures of life on extrasolar planets. In this paper we look for model independ definition of the habitable zone. It will be shown that the radius of the habitable sphere depends only on the constants of the Nature. Key words: Habitable sphere, fine structure constant.
Electric dipoles on the Bloch sphere
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.
Electric dipoles on the Bloch sphere
Vutha, Amar C.
2015-03-01
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 and molecular physics.
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 high...... temperatures. A phase diagram analogous to that of sterically stabilized colloids is proposed....
Marketing approach to management of service sphere
Остафійчук, Ярослав Васильович
2015-01-01
Approaches to management service sphere at different hierarchical levels with the use of marketing methodology have been considered. Functions of regional marketing in service sphere and its structure, possibilities of integration into marketing of components from other administrative conceptshave been analyzed.
International Nuclear Information System (INIS)
Conventional triple-axis neutron spectroscopy was developed by Brockhouse over thirty years ago' and remains today a versatile and powerful tool for probing the dynamics of condensed matter. The original design of the triple axis spectrometer is technically simple and probes momentum and energy space on a point-by-point basis. This ability to systematically probe the scattering function in a way which only requires a few angles to be moved under computer control and where the observed data in general can be analysed using a pencil and graph paper or a simple fitting routine, has been essential for the success of the method. These constraints were quite reasonable at the time the technique was developed. Advances in computer based data acquisition, neutron beam optics, and position sensitive area detectors have been gradually implemented on many triple axis spectrometer spectrometers, but the full potential of this has not been fully exploited yet. Further improvement in terms of efficiency (beyond point by point inspection) and increased sensitivity (use of focusing optics whenever the problem allows it) could easily be up to a factor of 10-20 over present instruments for many problems at a cost which is negligible compared to that of increasing the flux of the source. The real cost will be in complexity - finding the optimal set-up for a given scan and interpreting the data as the they are taken. On-line transformation of the data for an appropriate display in Q, ω space and analysis tools will be equally important for this task, and the success of these new ideas will crucially depend on how well we solve these problems. (author)
Mossbauer spectrometer radiation detector
Singh, J. J. (Inventor)
1973-01-01
A Mossbauer spectrometer with high efficiencies in both transmission and backscattering techniques is described. The device contains a sodium iodide crystal for detecting radiation caused by the Mossbauer effect, and two photomultipliers to collect the radiation detected by the crystal. When used in the transmission technique, the sample or scatterer is placed between the incident radiation source and the detector. When used in a backscattering technique, the detector is placed between the incident radiation source and the sample of scatterer such that the incident radiation will pass through a hole in the crystal and strike the sample. Diagrams of the instrument are provided.
Broadband multimode fiber spectrometer
Liew, Seng Fatt; Choma, Michael A; Tagare, Hemant D; Cao, Hui
2016-01-01
A general-purpose all-fiber spectrometer is demonstrated to overcome the trade-off between spectral resolution and bandwidth. By integrating a wavelength division multiplexer with five multimode optical fibers, we have achieved 100 nm bandwidth with 0.03 nm resolution at wavelength 1500 nm. An efficient algorithm is developed to reconstruct the spectrum from the speckle pattern produced by interference of guided modes in the multimode fibers. Such algorithm enables a rapid, accurate reconstruction of both sparse and dense spectra in the presence of noise.
Improvements to mass spectrometers
International Nuclear Information System (INIS)
This invention concerns mass spectrometers and, specifically, an ion beam analyser that facilitates the use of these spectrometers. Its object is to provide an improved apparatus for determining the desorption characteristics by field effect of a sample. It also aims to provide an improved system for carrying out sample analyses by using field effect desorption. Under the invention, facilities are added to the analyser to put out of action a part at least of the separation facilities so that the ion beam coming from the source of ions is not deflected. Detection means are located along the non deflected ion beam to detect the ions of the sample when they effectively appear and finally, actuating facilities are coupled to the out-of-action system so that the mass separation facilities may be brought back into action. This enables the operator to vary the parameters, such as the position of the source (emitter), the temperature and the electric field intensity until ions are released by the unknown sample
Simulation of the SAGE spectrometer
International Nuclear Information System (INIS)
The SAGE spectrometer combines a Ge-detector array with a Si detector to allow simultaneous detection of γ-rays and electrons. A comprehensive GEANT4 simulation package of the SAGE spectrometer has been developed with the ability to simulate the expected datasets based on user input files. The measured performance of the spectrometer is compared to the results obtained from the simulations. (orig.)
Simulation of the SAGE spectrometer
Energy Technology Data Exchange (ETDEWEB)
Cox, D.M.; Herzberg, R.D. [University of Liverpool, Department of Physics, Oliver Lodge Laboratory, Liverpool (United Kingdom); Konki, J.; Greenlees, P.T.; Pakarinen, J.; Papadakis, P.; Rahkila, P.; Sandzelius, M.; Sorri, J. [University of Jyvaeskylae, Department of Physics, Jyvaeskylae (Finland); Hauschild, K. [Universite Paris-Sud, CSNSM-IN2P3-CNRS, Orsay (France)
2015-06-15
The SAGE spectrometer combines a Ge-detector array with a Si detector to allow simultaneous detection of γ-rays and electrons. A comprehensive GEANT4 simulation package of the SAGE spectrometer has been developed with the ability to simulate the expected datasets based on user input files. The measured performance of the spectrometer is compared to the results obtained from the simulations. (orig.)
Cheng, Hongbo
2013-01-01
The Casimir energies for plate-sphere system and sphere-sphere system under PFA in the presence of one extra compactified universal dimension are analyzed. We find that the Casimir energy between a plate and a sphere in the case of sphere-based PFA is divergent. The Casimir energy of plate-sphere system in the case of plate-based PFA is finite and keeps negative. The extra-dimension corrections to the Casimir energy will be more manifest if the sphere is larger or farther away from the plate. It is shown that the negative Casimir energy for two spheres is also associated with the sizes of spheres and extra space. The larger spheres and the longer distance between them make the influence from the additional dimension stronger.
Cheng, Hongbo
2015-08-01
The Casimir energies for plate-sphere system and sphere-sphere systems under PFA in the presence of one extra compactified universal dimension are analyzed. We find that the Casimir energy between a plate and a sphere in the case of sphere-based PFA is divergent. The Casimir energy of plate-sphere system in the case of plate-based PFA is finite and keeps negative. The extra-dimension corrections to the Casimir energy will be more manifest if the sphere is larger or farther away from the plate. It is shown that the negative Casimir energy for two spheres is also associated with the sizes of spheres and extra space. The larger spheres and the longer distance between them make the influence from the additional dimension stronger.
Laser spectrometer of ion mobility
International Nuclear Information System (INIS)
The process of ion packet broadening in longitudinal laser spectrometer of ion mobility is studied. The contributions of diffusion, Coulomb and other broadening mechanisms are compared. The resolution of the developed spectrometer is measured (R ∼ 45) in atmospheres of both purified air and pure nitrogen. The dependence of the spectrometer resolution on the drift voltage is studied. The recorded spectra of some explosives with an extremely low pressure of saturated vapors indicate a high sensitivity of this spectrometer (no worse than 10-14 g/cm3)
Superelastic carbon spheres under high pressure
Li, Meifen; Guo, Junjie; Xu, Bingshe
2013-03-01
We report a superelastic deformation behavior of carbon spheres by the in situ Raman spectroscopy in a high-pressure diamond anvil cell. The carbon spheres produced by arc discharging in toluene have a mean diameter of 200 nm and an onion-like multilayer graphitic structure. We find that the elastic coefficients, during both the compression and decompression processes, remain a constant up to 10 GPa, indicating a superior high-pressure structural stability. Such superelastic behavior is related to the isotropic and concentric configuration of carbon spheres and provides additional insight into improving the microscopic mechanical properties of small-scale particles.
Two-sphere low Reynold's propeller
Najafi, Ali; Zargar, Rojman
2010-01-01
A three-dimensional model of a low-Reynold's swimmer is introduced and analyzed in this paper. This model consists of two large and small spheres connected by two perpendicular thin rods. The geometry of this system is motivated by the microorganisms that use a single tail to swim, the large sphere represents the head of microorganism and the small sphere resembles its tail. Each rod changes its length and orientation in a non-reciprocal manner that effectively propel the system. Translationa...
Neutron spectrum unfolding using neural networks
International Nuclear Information System (INIS)
An artificial neural network has been designed to obtain the neutron spectra from the Bonner spheres spectrometer's count rates. The neural network was trained using a large set of neutron spectra compiled by the International Atomic Energy Agency. These include spectra from iso- topic neutron sources, reference and operational neutron spectra obtained from accelerators and nuclear reactors. The spectra were transformed from lethargy to energy distribution and were re-binned to 31 energy groups using the MCNP 4C code. Re-binned spectra and UTA4 matrix were used to calculate the expected count rates in Bonner spheres spectrometer. These count rates were used as input and correspondent spectrum was used as output during neural network training. The network has 7 input nodes, 56 neurons as hidden layer and 31 neurons in the output layer. After training the network was tested with the Bonner spheres count rates produced by twelve neutron spectra. The network allows unfolding the neutron spectrum from count rates measured with Bonner spheres. Good results are obtained when testing count rates belong to neutron spectra used during training, acceptable results are obtained for count rates obtained from actual neutron fields; however the network fails when count rates belong to monoenergetic neutron sources. (Author)
Optical fiber smartphone spectrometer.
Hossain, Md Arafat; Canning, John; Cook, Kevin; Jamalipour, Abbas
2016-05-15
An optical fiber-based smartphone spectrometer incorporating an endoscopic fiber bundle is demonstrated. The endoscope allows transmission of the smartphone camera LED light to a sample, removing complications from varying background illumination. The reflected spectra collected from a surface or interface is dispersed onto the camera CMOS using a reflecting diffraction grating. A spectral resolution as low as δλ∼2.0 nm over a bandwidth of Δλ∼250 nm is obtained using a slit width, ωslit=0.7 mm. The instrument has vast potential in a number of industrial applications including agricultural produce analysis. Spectral analysis of apples shows straightforward measurement of the pigments anthocyanins, carotenoid, and chlorophyll, all of which decrease with increasing storage time. PMID:27176971
BNL multiparticle spectrometer software
International Nuclear Information System (INIS)
This paper discusses some solutions to problems common to the design, management and maintenance of a large high energy physics spectrometer software system. The experience of dealing with a large, complex program and the necessity of having the program controlled by various people at different levels of computer experience has led us to design a program control structure of mnemonic and self-explanatory nature. The use of this control language in both on-line and off-line operation of the program will be discussed. The solution of structuring a large program for modularity so that substantial changes to the program can be made easily for a wide variety of high energy physics experiments is discussed. Specialized tools for this type of large program management are also discussed
Thermoluminescence emission spectrometer.
Prescott, J R; Fox, P J; Akber, R A; Jensen, H E
1988-08-15
A sensitive thermoluminescence (TL) emission spectrometer based on Fourier transform spectroscopy is described. It employs a modified scanning Twyman-Green interferometer with photomultiplier detection in a photon-counting mode. The etendue is 180pi mm(2), and it covers the 350-600-nm wavelength range. The output can be displayed either as a 3-D isometric plot of intensity vs temperature and wavelength, as a contour diagram, or as a conventional TL glow curve of intensity vs temperature. It is sufficiently sensitive to record thermoluminescence spectra of dosimeter phosphors and minerals for thermoluminescence dating at levels corresponding to those found during actual use as radiation monitors or in dating. Examples of actual spectra are given. PMID:20539405
Directional spin wavelets on the sphere
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...
Acoustic levitation of a large solid sphere
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.
Entanglement entropy across a deformed sphere
Mezei, Márk
2014-01-01
I study the entanglement entropy (EE) across a deformed sphere in conformal field theories (CFTs). I show that the sphere (locally) minimizes the universal term in EE among all shapes. In arXiv:1407.7249 it was derived that the sphere is a local extremum, by showing that the contribution linear in the deformation parameter is absent. In this paper I demonstrate that the quadratic contribution is positive and is controlled by the coefficient of the stress tensor two point function, $C_T$. Such a minimization result contextualizes the fruitful relation between the EE of a sphere and the number of degrees of freedom in field theory. I work with CFTs with gravitational duals, where all higher curvature couplings are turned on. These couplings parametrize conformal structures in stress tensor $n$-point functions, hence I show the result for infinitely many CFT examples.
Exceptional cosmetic surgeries on homology spheres
Ravelomanana, Huygens C.
2016-01-01
We investigate the cosmetic surgery conjecture for hyperbolic knots in integer homology spheres, focusing on exceptional surgeries. We give some restrictions on the slopes of exceptional truly cosmetic surgeries according to the type of surgery.
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....
Elastic spheres can walk on water
Belden, Jesse; Hurd, Randy C.; Jandron, Michael A.; Bower, Allan F.; Truscott, Tadd T.
2016-02-01
Incited by public fascination and engineering application, water-skipping of rigid stones and spheres has received considerable study. While these objects can be coaxed to ricochet, elastic spheres demonstrate superior water-skipping ability, but little is known about the effect of large material compliance on water impact physics. Here we show that upon water impact, very compliant spheres naturally assume a disk-like geometry and dynamic orientation that are favourable for water-skipping. Experiments and numerical modelling reveal that the initial spherical shape evolves as elastic waves propagate through the material. We find that the skipping dynamics are governed by the wave propagation speed and by the ratio of material shear modulus to hydrodynamic pressure. With these insights, we explain why softer spheres skip more easily than stiffer ones. Our results advance understanding of fluid-elastic body interaction during water impact, which could benefit inflatable craft modelling and, more playfully, design of elastic aquatic toys.
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.
A sphere moving down the surface of a static sphere and a simple phase diagram
Jayanth, V; Biswas, Anindya Kumar
2008-01-01
A small sphere placed on the top of a big static frictionless sphere, slips until it leaves the surface at an angle $\\theta_{l}=\\cos^{-1}{2/3}$. On the other extreme, if the surface of the big sphere has coefficient of static friction, $\\mu_s\\to\\infty$, the small sphere starts rolling and continues to do so until it leaves the surface at an angle $\\theta_{l} =\\cos^{-1}{10/17}$. In the case where, $0\\leq\\mu_s<\\infty$, we get a simple phase diagram. The three phases are pure rolling, rolling with slipping and detached state. One phase line separates pure rolling from rolling with slipping. This diagram is obtained when stopping angles for pure rolling are plotted against static friction coefficients $\\mu_s$. Study in this article is restricted to the case when the mobile sphere starts at the top of the static sphere with infinitesimal kinetic energy.
Please comply: the water entry of soft spheres
Belden, Jesse; Hurd, Randy; Fanning, Tate; Jandron, Michael; Rekos, John; Bower, Allan; Truscott, Tadd
2015-11-01
The typical phenomena associated with sphere water impact are significantly altered when the sphere material is highly compliant rather than rigid. We describe the water impact physics of homogenous and hollow elastic spheres. The homogeneous spheres undergo large oscillatory deformations throughout entry that carve nested disturbances into the normally smooth air cavity, altering cavity shape and pinch off. Using an analytical model, we relate the maximum sphere deformation to the material properties and impact velocity. This characteristic deformation is used to reconcile the differences between cavities formed by compliant and rigid spheres. In addition to the nested disturbances seen with the homogeneous spheres, we observe azimuthal irregularities on the cavity during water entry of hollow elastic spheres. Based on experiments and finite-element modeling, we suggest that these disturbances are initiated by vibration mode shapes excited in the hollow spheres upon impact. For all sphere types, we compare the forces throughout water entry to the rigid sphere case.
Hollow sphere ceramic particles for abradable coatings
International Nuclear Information System (INIS)
A hollow sphere ceramic flame spray powder is disclosed. The desired constituents are first formed into agglomerated particles in a spray drier. Then the agglomerated particles are introduced into a plasma flame which is adjusted so that the particles collected are substantially hollow. The hollow sphere ceramic particles are suitable for flame spraying a porous and abradable coating. The hollow particles may be selected from the group consisting of zirconium oxide and magnesium zirconate
vSphere high performance cookbook
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.
Liouville Quantum Gravity on the Riemann Sphere
David, François; Kupiainen, Antti; Rhodes, Rémi; Vargas, Vincent
2016-03-01
In this paper, we rigorously construct Liouville Quantum Field Theory on the Riemann sphere introduced in the 1981 seminal work by Polyakov. We establish some of its fundamental properties like conformal covariance under PSL{_2({C})}-action, Seiberg bounds, KPZ scaling laws, KPZ formula and the Weyl anomaly formula. We also make precise conjectures about the relationship of the theory to scaling limits of random planar maps conformally embedded onto the sphere.
Surface polaritons on left-handed spheres
Ancey, Stéphane; Décanini, Yves; Folacci, Antoine; Gabrielli, Paul
2007-01-01
We consider the interaction of an electromagnetic field with a left-handed sphere, i.e., with a sphere fabricated from a left-handed material, in the framework of complex angular momentum techniques. We emphasize more particularly, from a semiclassical point of view, the resonant aspects of the problem linked to the existence of surface polaritons. We prove that the long-lived resonant modes can be classified into distinct families, each family being generated by one surface polariton propaga...
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.
vSphere virtual machine management
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.
Volume bounds of conic 2-spheres
Fang, Hao; Lai, Mijia
2016-01-01
We obtain sharp volume bound for a conic 2-sphere in terms of its Gaussian curvature bound. We also give the geometric models realizing the extremal volume. In particular, when the curvature is bounded in absolute value by $1$, we compute the minimal volume of a conic sphere in the sense of Gromov. In order to apply the level set analysis and iso-perimetric inequality as in our previous works, we develop some new analytical tools to treat regions with vanishing curvature.
Anisotropic fluid spheres in general relativity
International Nuclear Information System (INIS)
A procedure is developed to find static solutions for anisotropic fluid spheres from known static solutions for perfect fluid spheres. The method is used to obtain four exact analytical solutions of Einstein's equations for spherically symmetric self-gravitating distribution of anisotropic matter. The solutions are matched to the Schwarzschild exterior metric. The physical features of one of the solutions are briefly discussed. Many previously known perfect fluid solutions are derived as particular cases. (author)
A novel sampling theorem on the sphere
McEwen, J D
2011-01-01
We develop a novel sampling theorem on the sphere and corresponding fast algorithms by associating the sphere with the torus through a periodic extension. The fundamental property of any sampling theorem is the number of samples required to represent a band-limited signal. To represent exactly a signal on the sphere band-limited at L, all sampling theorems on the sphere require O(L^2) samples. However, our sampling theorem requires less than half the number of samples of other equiangular sampling theorems on the sphere and an asymptotically identical, but smaller, number of samples than the Gauss-Legendre sampling theorem. The complexity of our algorithms scale as O(L^3), however, the continual use of fast Fourier transforms reduces the constant prefactor associated with the asymptotic scaling considerably, resulting in algorithms that are fast. Furthermore, we do not require any precomputation and our algorithms apply to both scalar and spin functions on the sphere without any change in computational comple...
Innovation embedded in entrepreneurs’ networks in private and public spheres
DEFF Research Database (Denmark)
Schøtt, Thomas; Cheraghi, Maryam; Rezaei, Shahamak; Vang, Jan
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...... societies, China and Denmark. Global Entrepreneurship Monitor has surveyed entrepreneurs in China, Denmark and elsewhere. Analyses reconfirm the global tendencies and show that, China in contrast to Denmark, public sphere networking is sparser, but private sphere networking is denser. Innovation 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....
Collinear swimmer propelling a cargo sphere at low Reynolds number
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.
Terminal energy distribution of blast waves from bursting spheres
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.
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.
The Separate Spheres Model of Gendered Inequality.
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. PMID:26800454
VEGAS: VErsatile GBT Astronomical Spectrometer
Bussa, Srikanth; VEGAS Development Team
2012-01-01
The National Science Foundation Advanced Technologies and Instrumentation (NSF-ATI) program is funding a new spectrometer backend for the Green Bank Telescope (GBT). This spectrometer is being built by the CICADA collaboration - collaboration between the National Radio Astronomy Observatory (NRAO) and the Center for Astronomy Signal Processing and Electronics Research (CASPER) at the University of California Berkeley.The backend is named as VErsatile GBT Astronomical Spectrometer (VEGAS) and will replace the capabilities of the existing spectrometers. This backend supports data processing from focal plane array systems. The spectrometer will be capable of processing up to 1.25 GHz bandwidth from 8 dual polarized beams or a bandwidth up to 10 GHz from a dual polarized beam.The spectrometer will be using 8-bit analog to digital converters (ADC), which gives a better dynamic range than existing GBT spectrometers. There will be 8 tunable digital sub-bands within the 1.25 GHz bandwidth, which will enhance the capability of simultaneous observation of multiple spectral transitions. The maximum spectral dump rate to disk will be about 0.5 msec. The vastly enhanced backend capabilities will support several science projects with the GBT. The projects include mapping temperature and density structure of molecular clouds; searches for organic molecules in the interstellar medium; determination of the fundamental constants of our evolving Universe; red-shifted spectral features from galaxies across cosmic time and survey for pulsars in the extreme gravitational environment of the Galactic Center.
Spectrometers and Polyphase Filterbanks in Radio Astronomy
Price, Danny C
2016-01-01
This review gives an introduction to spectrometers and discusses their use within radio astronomy. While a variety of technologies are introduced, particular emphasis is given to digital systems. Three different types of digital spectrometers are discussed: autocorrelation spectrometers, Fourier transform spectrometers, and polyphase filterbank spectrometers. Given their growing ubiquity and significant advantages, polyphase filterbanks are detailed at length. The relative advantages and disadvantages of different spectrometer technologies are compared and contrasted, and implementation considerations are presented.
International Nuclear Information System (INIS)
The OPERA experiment will study νμ to ντ oscillations through τ appearance on the 732km long CERN to Gran Sasso baseline. The magnet yokes of the two muon spectrometers are instrumented with 48 planes of high resistivity bakelite Resistive Plate Chambers (RPC) operated in streamer mode. Each plane covers about 70m2. A general introduction to the system installation and commissioning will be given. Four RPC planes were instrumented and the first tests were performed confirming a good behavior of the installed RPCs in terms of intrinsic noise and operating currents. The measured noise maps agree with those obtained in the extensive quality test performed at surface. Counting rates are below 20Hz/m2. Single and multiple cosmic muon tracks were also reconstructed. The estimated efficiency is close to the geometrical limit and the very first measurements of the absolute and differential muon flux are in agreement with the expectations. Finally, a description of the readout electronics and of the slow control system is given
Energy Technology Data Exchange (ETDEWEB)
Garfagnini, A. [Padova University and INFN, Padova (Italy)]. E-mail: alberto.garfagnini@pd.infn.it; Bergnoli, A. [Padova University and INFN, Padova (Italy); Brugnera, R. [Padova University and INFN, Padova (Italy); Carrara, E. [Padova University and INFN, Padova (Italy); Ciesielski, R. [Padova University and INFN, Padova (Italy); Dal Corso, F. [Padova University and INFN, Padova (Italy); Dusini, S. [Padova University and INFN, Padova (Italy); Fanin, C. [Padova University and INFN, Padova (Italy); Longhin, A. [Padova University and INFN, Padova (Italy); Stanco, L. [Padova University and INFN, Padova (Italy); Cazes, A. [INFN Laboratori Nazionali di Frascati, Frascati (Italy); Cecchetti, A. [INFN Laboratori Nazionali di Frascati, Frascati (Italy); Di Troia, C. [INFN Laboratori Nazionali di Frascati, Frascati (Italy); Dulach, B. [INFN Laboratori Nazionali di Frascati, Frascati (Italy); Felici, G. [INFN Laboratori Nazionali di Frascati, Frascati (Italy); Mengucci, A. [INFN Laboratori Nazionali di Frascati, Frascati (Italy); Orecchini, D. [INFN Laboratori Nazionali di Frascati, Frascati (Italy); Paoloni, A. [INFN Laboratori Nazionali di Frascati, Frascati (Italy); Spinetti, M. [INFN Laboratori Nazionali di Frascati, Frascati (Italy); Terranova, F. [INFN Laboratori Nazionali di Frascati, Frascati (Italy); Ventura, M. [INFN Laboratori Nazionali di Frascati, Frascati (Italy); Votano, L. [INFN Laboratori Nazionali di Frascati, Frascati (Italy); Candela, A. [INFN Laboratori Nazionali del Gran Sasso, Assergi (Italy); D' Incecco, M. [INFN Laboratori Nazionali del Gran Sasso, Assergi (Italy); Gustavino, C. [INFN Laboratori Nazionali del Gran Sasso, Assergi (Italy); Lindozzi, M. [INFN Laboratori Nazionali del Gran Sasso, Assergi (Italy)
2007-03-01
The OPERA experiment will study {nu}{sub {mu}} to {nu}{sub {tau}} oscillations through {tau} appearance on the 732km long CERN to Gran Sasso baseline. The magnet yokes of the two muon spectrometers are instrumented with 48 planes of high resistivity bakelite Resistive Plate Chambers (RPC) operated in streamer mode. Each plane covers about 70m{sup 2}. A general introduction to the system installation and commissioning will be given. Four RPC planes were instrumented and the first tests were performed confirming a good behavior of the installed RPCs in terms of intrinsic noise and operating currents. The measured noise maps agree with those obtained in the extensive quality test performed at surface. Counting rates are below 20Hz/m{sup 2}. Single and multiple cosmic muon tracks were also reconstructed. The estimated efficiency is close to the geometrical limit and the very first measurements of the absolute and differential muon flux are in agreement with the expectations. Finally, a description of the readout electronics and of the slow control system is given.
Aerosol mobility size spectrometer
Wang, Jian; Kulkarni, Pramod
2007-11-20
A device for measuring aerosol size distribution within a sample containing aerosol particles. The device generally includes a spectrometer housing defining an interior chamber and a camera for recording aerosol size streams exiting the chamber. The housing includes an inlet for introducing a flow medium into the chamber in a flow direction, an aerosol injection port adjacent the inlet for introducing a charged aerosol sample into the chamber, a separation section for applying an electric field to the aerosol sample across the flow direction and an outlet opposite the inlet. In the separation section, the aerosol sample becomes entrained in the flow medium and the aerosol particles within the aerosol sample are separated by size into a plurality of aerosol flow streams under the influence of the electric field. The camera is disposed adjacent the housing outlet for optically detecting a relative position of at least one aerosol flow stream exiting the outlet and for optically detecting the number of aerosol particles within the at least one aerosol flow stream.
Experimental verification of a new neutron spectrometer for environmental dosimetry and area
International Nuclear Information System (INIS)
In this communication, we present experimental results with a new neutron spectrometer, developed jointly by the Radiation Dosimetry Unit of CIEMAT Unita di Fisica and INFN-LNF Sanitary (Italy), consisting of a polyethylene moderating sphere detectors thermal neutrons (paired thermoluminescent dosimeters and activation foils) located in different positions. The device configuration and distribution of dosimeters are designed to elicit a response in a nearly isotropic up to 20 MeV energy range. (Author)
Adaptive Computed Tomography Imaging Spectrometer Project
National Aeronautics and Space Administration — The present proposal describes the development of an adaptive Computed Tomography Imaging Spectrometer (CTIS), or "Snapshot" spectrometer which can...
Novel Micro Fourier Transform Spectrometers
Institute of Scientific and Technical Information of China (English)
KONG Yan-mei; LIANG Jing-qiu; LIANG Zhong-zhu; WANG-Bo; ZHANG Jun
2008-01-01
The miniaturization of spectrometer opens a new application area with real-time and on-site measurements. The Fourier transform spectrometer(FTS) is much attractive considering its particular advantages among the approaches. This paper reviews the current status of micro FTS in worldwide and describes its developments; In addition, analyzed are the key problems in designing and fabricating FTS to be settled during the miniaturization. Finally, a novel model of micro FTS with no moving parts is proposed and analyzed, which may provide new concepts for the design of spectrometers.
Robotics Programming Competition Spheres, Russian Part
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.
The thermal conductivity of beds of spheres
Energy Technology Data Exchange (ETDEWEB)
McElroy, D.L.; Weaver, F.J.; Shapiro, M.; Longest, A.W.; Yarbrough, D.W.
1987-01-01
The thermal conductivities (k) of beds of solid and hollow microspheres were measured using two radial heat flow techniques. One technique provided k-data at 300 K for beds with the void spaces between particles filled with argon, nitrogen, or helium from 5 kPa to 30 MPa. The other technique provided k-data with air at atmospheric pressure from 300 to 1000 K. The 300 K technique was used to study bed systems with high k-values that can be varied by changing the gas type and gas pressure. Such systems can be used to control the operating temperature of an irradiation capsule. The systems studied included beds of 500 ..mu..m dia solid Al/sub 2/O/sub 3/, the same Al/sub 2/O/sub 3/ spheres mixed with spheres of silica--alumina or with SiC shards, carbon spheres, and nickel spheres. Both techniques were used to determine the k-value of beds of hollow spheres with solid shells of Al/sub 2/O/sub 3/, Al/sub 2/O/sub 3//center dot/7 w/o Cr/sub 2/O/sub 3/, and partially stabilized ZrO/sub 2/. The hollow microspheres had diameters from 2100 to 3500 ..mu..m and wall thicknesses from 80 to 160 ..mu..m. 12 refs., 7 figs., 4 tabs.
Automated transportable mass spectrometer
International Nuclear Information System (INIS)
The need has been identified for a Mass Spectrometer (MS) which can be conveniently transported among several facilities for rapid verification of the isotopic composition of Special Nuclear Material. This requirement for a light weight, transportable MS for U and Pu mass analysis was met by deleting the gas chromatograph (GC) portions of a Hewlett-Packard (H-P) Model 5992 Quadrupole GCMS and substituting a vacuum lock sample entry system. A programmable power supply and vacuum gauge were added and circuitry modifications were made to enable use of the supplied software. The single rhenium filament plug-in source is loaded with either a nominal microliter of sample solution and evaporated, or with a prepared resin bead. Using a resin bead in a specially dimpled filament, copious sensitivity is obtained with 30 nanogram uranium samples. After sample insertion the analysis is completely controlled by an H-P Model 9825 calculator. Source vacuum of 2 x 10-7 torr or better is regained within 2 minutes after sample insertion, and total time for a complete analysis is about 7 minutes. Accuracy is better than 1% for isotope ratios less than 20 and better than 2% for ratios of 100. Ions are accelerated at about 1.8 volts into the mass filter which has pole pieces of hyperbolic cross section. Collection is by a Galileo Channeltron multiplier into a log preamp. During a normal run, 1.4 x 106 data point are observed and averaged. Weight of the instrument excluding the calculator is 88 Kg which allows relatively easy transportation over short distances by two persons. The instrument can be carried into a facility and be ready to analyze samples in less than 3 hours
High energy electron crystal spectrometer
International Nuclear Information System (INIS)
A spectrometer has been developed to measure relativistic electrons produced in different types of plasmas, such as tokamak plasmas and laser produced plasmas. The spectrometer consists of nine Y2SiO5:Ce crystals, which are shielded by stainless steel filters. The absolute calibration of the spectrometer was performed at the superconducting electron linear accelerator Electron Linac for beams with high Brilliance and low Emittance. The spectrometer can provide information about energy distribution of electrons and their numbers for the energy range between 4 and 30 MeV. The spectrum is analyzed by means of the Monte Carlo three-dimensional GEANT4 code. An energy resolution of about 10% is achieved.
Semiconductor spectrometer for radiation protection
International Nuclear Information System (INIS)
The radiation fields on aircraft board and for other radiation protection application are complexes they contain the particles with energies up to few hundreds MeV. Obviously, one distinguishes the components with low resp. high linear energy transfer (LET). Recently, we have acquired a new measuring instrument, MDU-LIULIN, an energy deposition spectrometer base on a Si-detector. The spectrometer was originally developed and largely tested onboard of cosmic vehicles, its sensitive element is a Si-diode. The spectrometer has been calibrated in photon, neutron and high-energy radiation reference fields (CERN). The energy deposited in the detector by a particle is analysed by a 256-channel spectrum analyser, it permits to distinguish the contribution of different types of radiation to integral dosimetry quantities. The spectrometer has been, since April 2000 used for some radiation protection applications, mostly on aircraft board. Results obtained are presented, discussed and analysed. Materials and methods. (authors)
An antimatter spectrometer in space
International Nuclear Information System (INIS)
We discuss a simple magnetic spectrometer to be installed on a satellite or space station. The purpose of this spectrometer is to search for primordial antimatter to the level of antimatter/matter ∼10-9, improving the existing limits obtained with balloon flights by a factor of 104 to 105. The design of the spectrometer is based on an iron-free, Nd-Fe-B permanent magnet, scintillation counters, drift tubes, and silicon or time projection chambers. Different design options are discussed. Typically, the spectrometer has a weight of about 2 tons and an acceptance of about 1.0 m2 sr. The availability of the new Nd-Fe-B material makes it possible for the first time to put a magnet into space economically and reliably. ((orig.))
Java meshing tool for sphere arrangements
International Nuclear Information System (INIS)
A tool for meshing sphere arrangements was programmed in order to perform finite element calculations. Sphere arrangements are investigated in frame of the feasibility study of the sphere-pac nuclear fuel. One major concern of this study is the thermal conductivity of the arrangement. Further concerns are the mechanical behavior and sintering of the fuel. The thermal conductivity of the fuel was addressed with the computer code SPACON based on a unit cell approach and a radial heat flow experiment. However, a further approach using the finite element method is desirable, in order to better understanding the thermal flow through the package and to cross check with SPACON data and with experimental data. Also the mechanical behavior of the fuel could be addressed using the finite element technique. (author)
Two-sphere low Reynold's propeller
Najafi, Ali
2010-01-01
A three-dimensional model of a low-Reynold's swimmer is introduced and analyzed in this paper. This model consists of two large and small spheres connected by two perpendicular thin rods. The geometry of this system is motivated by the microorganisms that use a single tail to swim, the large sphere represents the head of microorganism and the small sphere resembles its tail. Each rod changes its length and orientation in a non-reciprocal manner that effectively propel the system. Translational and rotational velocities of the swimmer are studied for different values of parameters. Our findings show that by changing the parameters we can adjust both the velocity and the direction of motion of the swimmer.
Polarimetric spectrometer for Italian Radiotelescopes .
Russo, A.
A new spectrometer has been designed and tested at the Radioastronomy Laboratory of Arcetri Astrophysical Observatory. It provides a resolution of 4096 spectral points over a bandwidth selectable between 0.5 and 125 MHz. It can analyze up to 8 independent signals with full polarimetric capabilities. This spectrometer can be used as back-end for a 7 channels double polarization radio receiver,working in the frequency range 18-26 GHz, implemented in the same laboratory.
Scalar Solitons on the Fuzzy Sphere
Austing, P; Thorlacius, L; Austing, Peter; Jonsson, Thordur; Thorlacius, Larus
2002-01-01
We study scalar solitons on the fuzzy sphere at arbitrary radius and noncommutativity. We prove that no solitons exist if the radius is below a certain value. Solitons do exist for radii above a critical value which depends on the noncommutativity parameter. We construct a family of soliton solutions which are stable and which converge to solitons on the Moyal plane in an appropriate limit. These solutions are rotationally symmetric about an axis and have no allowed deformations. Solitons that describe multiple lumps on the fuzzy sphere can also be constructed but they are not stable.
Path integral representations on the complex sphere
International Nuclear Information System (INIS)
In this paper we discuss the path integral representations for the coordinate systems on the complex sphere S3C. 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.)
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.
Scattering by two spheres: Theory and experiment
DEFF Research Database (Denmark)
Bjørnø, Irina; Jensen, Leif Bjørnø
1998-01-01
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 the......Extensive studies of scattering of acoustical signals by targets of different regular shapes have formed a useful background for attempts to develop procedures for remote monitoring of suspended materials in marine environments as, for instance, measurements of characteristic parameters of...
Bridging conflicting innovation spheres of tourism innovation
DEFF Research Database (Denmark)
Fuglsang, Lars; Sørensen, Flemming; Nordli, Anne Jørgensen
2016-01-01
competition which may inhibit networked and open innovation. Tourist destinations are examples of such localized systems. In this paper we present two extreme cases of tourist destinations in which collaborative innovation processes were established in spite of fierce disagreements between actors. We argue...... that in tourist destinations actors belong to conflicting innovation spheres but can be brought together in innovation processes when a diplomat enable compromises and when innovation spheres change from personalized to more generalized forms of activity during interaction. The findings are relevant...
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.
Steel Spheres and Skydiver--Terminal Velocity
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.
Transnational public spheres : A spatial perspective
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
Pious Entertainment: Hizbullah's Islamic Cultural Sphere
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
Einstein Metrics on Rational Homology Spheres
Boyer, Charles P.; Galicki, Krzysztof
2003-01-01
We prove the existence of Sasakian-Einstein metrics on infinitely many rational homology spheres in all odd dimensions greater than 3. In dimension 5 we obain somewhat sharper results. There are examples where the number of effective parameters in the Einstein metric grows exponentially with dimension.
Casimir stress on lossy magnetodielectric spheres
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.
String Field Theory and the Fuzzy Sphere
Ita, Harald; Oz, Yaron
2001-01-01
We use boundary string field theory to study open string tachyon condensation on a three-sphere closed string background. We consider the closed string background described by $SU(2)_k$ WZW model in the limit of large $k$. We compute the exact tachyon potential and analyse the decay modes.
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.
On configuration spaces of hard spheres
Baryshnikov, Yuliy; Kahle, Matthew
2011-01-01
We study configuration spaces of hard spheres in a bounded region. We develop a general Morse-theoretic framework, and show that mechanically balanced configurations play the role of critical points. As an application, we find the precise threshold radius for a configuration space to be homotopy equivalent to the configuration space of points.
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.
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.
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...... contexts such as search-and-rescue missions and medical or biological studies....
Second virial coefficients of dipolar hard spheres
Philipse, A.P.; Kuipers, B.W.M.
2010-01-01
An asymptotic formula is reported for the second virial coefficient B2 of a dipolar hard-sphere (DHS) fluid, in zero external field, for strongly coupled dipolar interactions. This simple formula, together with the one for the weak-coupling B2, provides an accurate prediction of the second virial co
Ligand sphere conversions in terminal carbide complexes
DEFF Research Database (Denmark)
Morsing, Thorbjørn Juul; Reinholdt, Anders; Sauer, Stephan P. A.; Bendix, Jesper
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...
DNS of Swirling Flow Past a Sphere
Higgins, Keith; Ooi, Andrew; Chong, Min; Balachandar, S.
2001-11-01
Experimental investigations into the swirling flow past a sphere have revealed a range of surprising and complex flow phenomena. These results have advanced our understanding in applications such as particle entrainment and the combustion of fuel droplets. Renewed interest in this problem has been kindled by recent experimental observations. (Mattner et al. 2001, submitted for review to J. Fluid Mech.) This has motivated the development of a fully spectral direct numerical simulation of the three-dimensional time-dependent swirling flow past a sphere. The effect of swirl on the various transitions in the wake structure behind a sphere is unknown. The main objective of our study is to identify transitions that occur with increasing Reynolds number and swirl strength. Firstly, we show the effect of swirl strength on the axisymmetric sphere wake and drag. Then, using a three-dimensional simulation, we examine the effect of swirl on the time histories of the lift, drag and velocities. We hope to show some visualisations of the topology of the 3D wake flow using the invariants of the velocity gradient tensor.
Metal-Matrix/Hollow-Ceramic-Sphere Composites
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.
Turbulent drag reduction using fluid spheres
Gillissen, J.J.J.
2013-01-01
Using direct numerical simulations of turbulent Couette flow, we predict drag reduction in suspensions of neutrally buoyant fluid spheres, of diameter larger than the Kolmogorov length scale. The velocity fluctuations are enhanced in the streamwise direction, and reduced in the cross-stream directio
Full sphere hydrodynamic and dynamo benchmarks
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.
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.
VMware vSphere PowerCLI Reference Automating vSphere Administration
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
International Nuclear Information System (INIS)
Using carbonyl iron as template, hollow nickel spheres were prepared by electroless plating on carbonyl iron and template corrosion method. The samples were characterized by X-ray diffraction (XRD), X-ray fluorescence spectrometer (XRF), transmission electron microscope (TEM), scanning electron microscope (SEM), vibrating sample magnetometer (VSM) and vector network analyzer. Results showed that the shell thickness can be controlled by adjusting the loadage of carbonyl iron templates. The hollow nickel spheres exhibited good magnetic properties with a saturation magnetization of 48.56 emu/g and enhanced coercivity (as high as 260 Oe). The real (ε′) and imaginary (ε″) parts of complex permittivity of hollow nickel spheres first increased and then decreased as the shell thickness increased, and the sample with the thinnest shell showed the lowest complex permittivity. For the complex permeability, the resonance peak shifted to the lower frequency and then moved to higher frequency, as the shell thickness increased. The microwave absorption performances could be tuned by changing the shell thickness. In this study, the minimum reflection loss (RL) value of −27.2 dB was obtained at 13.4 GHz with a matching thickness of 1.4 mm and the effective absorption band (RL <−5 dB) from 11.8 to 18 GHz, covering the whole Ku-band (12.4−18 GHz).
Cavity formation by the impact of Leidenfrost spheres
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.
Global Calibration of Multiple Cameras Based on Sphere Targets
Junhua Sun; Huabin He; Debing Zeng
2016-01-01
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 sphe...
Portable smartphone optical fibre spectrometer
Hossain, Md. Arafat; Canning, John; Cook, Kevin; Jamalipour, Abbas
2015-09-01
A low cost, optical fibre based spectrometer has been developed on a smartphone platform for field-portable spectral analysis. Light of visible wavelength is collected using a multimode optical fibre and diffracted by a low cost nanoimprinted diffraction grating. A measurement range over 300 nm span (λ = 400 to 700 nm) is obtained using the smartphone CMOS chip. The spectral resolution is Δλ ~ 0.42 nm/screen pixel. A customized Android application processed the spectra on the same platform and shares with other devices. The results compare well with commercially available spectrometer.
The Bruny Island Radio Spectrometer
Erickson, W. C.
1997-11-01
A radio spectrometer has been built on Bruny Island, south of Hobart, for the study of solar bursts in the rarely observed frequency range from 3 to 20 MHz. This spectrometer is an adaptive device that employs digital techniques to avoid most of the strong terrestrial interference prevalent in this frequency range. The residual interference that cannot be avoided is excised during off-line processing. As a result, successful observations are made down to the minimum frequency that can propagate through the ionosphere to the antenna. This minimum frequency depends upon the zenith distance of the Sun and it is usually between 4 and 8 MHz.
Laboratory Calibration of a Field Imaging Spectrometer System
Directory of Open Access Journals (Sweden)
Qingxi Tong
2011-02-01
Full Text Available A new Field Imaging Spectrometer System (FISS based on a cooling area CCD was developed. This paper describes the imaging principle, structural design, and main parameters of the FISS sensor. The FISS was spectrally calibrated with a double grating monochromator to determine the center wavelength and FWHM of each band. Calibration results showed that the spectral range of the FISS system is 437–902 nm, the number of channels is 344 and the spectral resolution of each channel is better than 5 nm. An integrating sphere was used to achieve absolute radiometric calibration of the FISS with less than 5% calibration error for each band. There are 215 channels with signal to noise ratios (SNRs greater than 500 (62.5% of the bands. The results demonstrated that the FISS has achieved high performance that assures the feasibility of its practical use in various fields.
Complex data processing: fast wavelet analysis on the sphere
Wiaux, Y; Vielva, P
2007-01-01
In the general context of complex data processing, this paper reviews a recent practical approach to the continuous wavelet formalism on the sphere. This formalism notably yields a correspondence principle which relates wavelets on the plane and on the sphere. Two fast algorithms are also presented for the analysis of signals on the sphere with steerable wavelets.
21 CFR 886.3320 - Eye sphere implant.
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...
International Nuclear Information System (INIS)
With the Bonner spheres spectrometer neutron spectrum is obtained through an unfolding procedure. Monte Carlo methods, Regularization, Parametrization, Least-squares, and Maximum Entropy are some of the techniques utilized for unfolding. In the last decade methods based on Artificial Intelligence Technology have been used. Approaches based on Genetic Algorithms and Artificial Neural Networks (Ann) have been developed in order to overcome the drawbacks of previous techniques. Nevertheless the advantages of Ann still it has some drawbacks mainly in the design process of the network, vg the optimum selection of the architectural and learning Ann parameters. In recent years the use of hybrid technologies, combining Ann and genetic algorithms, has been utilized to. In this work, several Ann topologies were trained and tested using Ann and Genetically Evolved Artificial Neural Networks in the aim to unfold neutron spectra using the count rates of a Bonner sphere spectrometer. Here, a comparative study of both procedures has been carried out. (Author)
Theory of tectonics in the sphere
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.
Packing circles and spheres on surfaces
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.
Second-Generation Curvelets on the Sphere
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.
Packing circles and spheres on surfaces
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.
Neutron monitoring using moderating sphere detectors
International Nuclear Information System (INIS)
Three moderating sphere-detector systems are examined as a neutron area monitoring instruments. The thermal neutron detectors used are the (bare-Cd covered) Li6 (Eu) crystal scintillating detector, the U235-mica track detector and the partially Cd-covered R.M. film. The response of the 12 s sphere-detector systems to Pu-Be neutrons are found to be 0.22 counts/neutrons for the Li6I-system. 8x10-4 tracks per neutron for the track-detector system and 10 mR equivalent γ-ray exposure per 2x10-neutrons per cm- for the Cd-covered R.M. film system
Event Driven Langevin simulations of Hard Spheres
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.
Wavelets, ridgelets and curvelets on the sphere
Starck, J L; Abrial, P; Nguyen, M; Starck, Jean-Luc; Moudden, Yassir; Abrial, Pierrick; Nguyen, Mai
2005-01-01
We present in this paper new multiscale transforms on the sphere, namely the isotropic undecimated wavelet transform, the pyramidal wavelet transform, the ridgelet transform and the curvelet transform. All of these transforms can be inverted i.e. we can exactly reconstruct the original data from its coefficients in either representation. Several applications are described. We show how these transforms can be used in denoising and especially in a Combined Filtering Method, which uses both the wavelet and the curvelet transforms, thus benefiting from the advantages of both transforms. An application to component separation from multichannel data mapped to the sphere is also described in which we take advantage of moving to a wavelet representation.
Bidirectional reflection effects in practical integrating spheres.
Mahan, J R; Walker, J A; Stancil, M M
2015-10-20
Integrating spheres play a central role in radiometric instrument calibration, surface optical property measurement, and radiant source characterization. Our work involves a simulation, based on the Monte Carlo ray-trace (MCRT) of bidirectional reflections within a practical integrating sphere pierced with two viewing ports. We used data from the literature to create an empirical model for the bidirectional reflection distribution function (BRF) of Spectralon suitable for use in the MCRT environment. The ratio of power escaping through the two openings is shown to vary linearly with wall absorptivity for both diffuse and bidirectional reflections. The sensitivity of this ratio to absorptivity is shown to be less when reflections are weakly bidirectional. PMID:26560384
Ceramica sphere production by a gel casting
International Nuclear Information System (INIS)
The technology of (Th,U)O2 microspheres production by gel casting and subsequente thermal treatment has been transferred from NUKEM GmbH assisted by Kraftwerk Union A.G., both West Germany, to NUCLEBRAS, where it was jointly adapted to produce microspheres suitable for pressing. As a result, there are now available various possibilities to produce ceramic spheres with different characteristics that can be used in different applications. Examples of these characteristics are the range of gel sphere diameters (200 to 5000 μmm) and the value of the specific surface (about 50m2/g for calcined (Th, U)O2 and potentially higher than m2/g for other ceramic materials) (Author)
Statistical inference for disordered sphere packings
Directory of Open Access Journals (Sweden)
Jeffrey Picka
2012-01-01
Full Text Available This paper gives an overview of statistical inference for disordered sphere packing processes. These processes are used extensively in physics and engineering in order to represent the internal structure of composite materials, packed bed reactors, and powders at rest, and are used as initial arrangements of grains in the study of avalanches and other problems involving powders in motion. Packing processes are spatial processes which are neither stationary nor ergodic. Classical spatial statistical models and procedures cannot be applied to these processes, but alternative models and procedures can be developed based on ideas from statistical physics.Most of the development of models and statistics for sphere packings has been undertaken by scientists and engineers. This review summarizes their results from an inferential perspective.
Quantum Isometry groups of the Podles Spheres
Bhowmick, Jyotishman; Goswami, Debashish
2008-01-01
For $\\mu \\in (0,1), c> 0,$ we identify the quantum group $SO_\\mu(3)$ as the universal object in the category of compact quantum groups acting by `orientation and volume preserving isometries' in the sense of \\cite{goswami2} on the natural spectral triple on the Podles sphere $S^2_{\\mu, c}$ constructed by Dabrowski, D'Andrea, Landi and Wagner in \\cite{{Dabrowski_et_al}}.
Poincar\\'e Sphere and Decoherence Problems
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.
Semiclassical collapse of a sphere of dust
Roberto CasadioDepartment of Physics University of Bologna and Istituto Nazionale di Fisica Nucleare, Sezione di Bologna; Giovanni Venturi(Department of Physics, University of Bologna, and Istituto Nazionale di Fisica Nucleare, Sezione di Bologna, Italy)
2015-01-01
The semiclassical collapse of a homogeneous sphere of dust is studied. After identifying the independent dynamical variables, the system is canonically quantised and coupled equations describing matter (dust) and gravitation are obtained. The conditions for the validity of the adiabatic (Born--Oppenheimer) and semiclassical approximations are derived. Further on neglecting back--reaction effects, it is shown that in the vicinity of the horizon and inside the dust the Wightman function for a c...
From Noncommutative Sphere to Nonrelativistic Spin
Deriglazov, Alexei A.(Dept. de Matematica, ICE, Universidade Federal de Juiz de Fora, MG, Brazil)
2009-01-01
Reparametrization invariant dynamics on a sphere, being parameterized by angular momentum coordinates, represents an example of noncommutative theory. It can be quantized according to Berezin-Marinov prescription, replacing the coordinates by Pauli matrices. Following the scheme, we present two semiclassical models for description of spin without use of Grassman variables. The first model implies Pauli equation upon the canonical quantization. The second model produces nonrelativistic limit o...
From Noncommutative Sphere to Nonrelativistic Spin
Deriglazov, Alexei A.
2010-02-01
Reparametrization invariant dynamics on a sphere, being parameterized by angular momentum coordinates, represents an example of noncommutative theory. It can be quantized according to Berezin-Marinov prescription, replacing the coordinates by Pauli matrices. Following the scheme, we present two semiclassical models for description of spin without use of Grassman variables. The first model implies Pauli equation upon the canonical quantization. The second model produces nonrelativistic limit of the Dirac equation implying correct value for the electron spin magnetic moment.
From Noncommutative Sphere to Nonrelativistic Spin
Directory of Open Access Journals (Sweden)
Alexei A. Deriglazov
2010-02-01
Full Text Available Reparametrization invariant dynamics on a sphere, being parameterized by angular momentum coordinates, represents an example of noncommutative theory. It can be quantized according to Berezin-Marinov prescription, replacing the coordinates by Pauli matrices. Following the scheme, we present two semiclassical models for description of spin without use of Grassman variables. The first model implies Pauli equation upon the canonical quantization. The second model produces nonrelativistic limit of the Dirac equation implying correct value for the electron spin magnetic moment.
On the revolution of heavenly spheres
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.
Soft-sphere model for liquid metals
International Nuclear Information System (INIS)
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
The sea - landfill or sphere of life
International Nuclear Information System (INIS)
The Environmental Information Agency held its third seminar for journalists, entitled 'The sea - landfill or sphere of life' in Hamburg on July 18, 1989. Some 40 journalists - radio journalists and journalists from the staff of dailies and the technical press - took the opportunity to listen for a day to short lectures on selected subjects and submit their questions concerning sea pollution to scientists of diverse disciplines. (orig.)
Spheres of diversities: from concept to policy
Zapata Barrero, Ricard; Ewijk, Anne R. van
2011-01-01
This book is concerned with the diversity debate in the context of Europe. It is about diversity both as a concept and as a policy. Indeed, the epicentre of the analysis is the link between the spheres of diversity-concepts and diversity-policies. The book explores how the concept of diversity orientates policies and management, and also how public/private management facilitates new policy orientations. As such, the book enhances conceptual thinking on diversity, but also fa...
Supersymmetric theories on squashed five-sphere
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.
Turbulator Diameter and Drag on a Sphere
Directory of Open Access Journals (Sweden)
Nicholas Robson
2009-01-01
Full Text Available A sphere with turbulators of varying diameter was pulled through water with constant force. The relationship between the diameter of the turbulators and the ball’s total coefficient of drag was determined. The maximum drag reduction was found with turbulators of 0.002 m. The drag reduction was less for turbulators of sizes 0.004 m and 0.005 m.
The Separate Spheres Model of Gendered Inequality
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 psychologic...
Event Driven Langevin simulations of Hard Spheres
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 int...
JAERI Tandem neutron TOF spectrometer
International Nuclear Information System (INIS)
The layout of the neutron TOF spectrometer at JAERI Tandem Accelerator for the scattering measurement in 10-40 MeV and the data acquisition/process system are described. The result of the 28Si(n,n) and (n,n') at En=13 MeV is shown and the great improvement of the counting efficiency is obtained. (author)
Mirrors for pion spectrometer DIRAC
Czech Academy of Sciences Publication Activity Database
Pech, Miroslav; Schovánek, Petr; Hrabovský, Miroslav; Řídký, Jan; Mandát, Dušan; Nožka, Libor; Palatka, Miroslav
1. Olomouc : Univerzita Palackého v Olomouci, 2006 - (Křepelka, J.), s. 109-110 ISBN 80-244-1544-5 R&D Projects: GA MŠk(CZ) 1M06002 Institutional research plan: CEZ:AV0Z10100522 Keywords : mirrors * pion spectrometer DIRAC Subject RIV: BH - Optics, Masers, Lasers
The GRAD gamma ray spectrometer
Energy Technology Data Exchange (ETDEWEB)
Rester, A.C.; Piercey, R.B.; Eichhorn, G.; Coldwell, R.L.; McKisson, J.M.; Ely, D.W.; Mann, H.M.; Jenkins, D.A.
1986-02-01
A gamma-ray spectrometer for an upcoming space shuttle mission is described. Consisting of a 150 cm/sup 3/ n-type germanium detector set inside active shielding of bismuth germanate and plastic scintillator, the instrument will be used in studies of the Orbiter background and the galactic center.
The GRAD gamma ray spectrometer
International Nuclear Information System (INIS)
A gamma-ray spectrometer for an upcoming space shuttle mission is described. Consisting of a 150 cm3 n-type germanium detector set inside active shielding of bismuth germanate and plastic scintillator, the instrument will be used in studies of the Orbiter background and the galactic center
G-Fresnel smartphone spectrometer.
Zhang, Chenji; Cheng, Gong; Edwards, Perry; Zhou, Ming-Da; Zheng, Siyang; Liu, Zhiwen
2016-01-21
We report a smartphone spectrometer with nanometer resolution working in the visible range. A G-Fresnel device with the dual functionality of focusing and dispersion is used to enable miniaturization. Proof of principle application to Bradford assay of protein concentration is also demonstrated. PMID:26645747
The smallsat TIR spectrometer MIBS
Leijtens, J.A.P.; Court, A.J.; Lucas, J.W.
2005-01-01
In frame of the ESA Earthcare MSI study, TNO Science and Industry has developed a compact spectrometer which is optimized for operation in the 7 to 14 μm wavelength region. By optimizing the throughput of the system, and using the advantages of modern manufacturing technologies to the largest extend
Sticky red spheres can be used to capture western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), but whether they capture more flies than yellow spheres and panels is poorly known. The objective of this study was to compare fly captures on red spheres versus yellow traps so...
Agglomeration techniques for the production of spheres for packed beds
International Nuclear Information System (INIS)
One attractive fusion-breeder-blanket design features a lithium bearing ceramic in the form of spheres packed into a random array. The spheres have diameters of 3 mm and 0.3 mm. This report surveys techniques used to produce ceramic spheres on an industrial scale. The methods examined include tumbling and mixing granulation, extrusion, briquetting and pelletizing. It is concluded that the required quantities of 0.3 mm diameter spheres can be produced by the tumbling agglomeration of a feed powder. The 3 mm diameter spheres will be made using a process of extrusion, chopping and rolling
Neutronic fields produced by a lineal accelerator for radiotherapy
International Nuclear Information System (INIS)
Measurements and Monte Carlo calculations has been utilized to determine the dosimetric features as well as the neutron spectra of photoneutrons produced around an 18 MV linear accelerator for radiotherapy. Measurements were carried out with bare and Cd covered thermoluminescent dosimeters, TLD600 and TLD700, as well as inside a paraffine moderator. TLD pairs were also utilized as thermal neutrons inside a Bonner sphere spectrometer (au)
Neutron spectra and dosimetric assessment around a neutron Howitzer container
Barros, Silvia; Gallego Díaz, Eduardo F.; Lorente Fillol, Alfredo; Gonçalves, Isabel F.; Vaz, Pedro; Vega-Carrillo, Héctor René; Zankl, María
2014-01-01
The neutron Howitzer container at the Neutron Measurements Laboratory of the Nuclear Engineering Department of the Polytechnic University of Madrid (UPM), is equipped with a 241Am-Be neutron source of 74 GBq in its center. The container allows the source to be in either the irradiation or the storage position. To measure the neutron fluence rate spectra around the Howitzer container, measurements were performed using a Bonner spheres spectrometer and the spectra were unfolded using the NSDann...
Artificial Neural Networks in Spectrometry and Neutron Dosimetry
International Nuclear Information System (INIS)
The ANN technology has been applied to unfold the neutron spectra of three neutron sources and to estimate their dosimetric features. To compare these results, neutron spectra were also unfolded with the BUNKIUT code. Both unfolding procedures were carried out using the count rates of a Bonner sphere spectrometer. The spectra unfolded with ANN result similar to those unfolded with the BUNKIUT code. The H*(10) values obtained with ANN agrees well with H*(10) values calculated with the BUNKIUT code.
Confined disordered strictly jammed binary sphere packings
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
Hopf Maps, Lowest Landau Level, and Fuzzy Spheres
Directory of Open Access Journals (Sweden)
Kazuki Hasebe
2010-09-01
Full Text Available This paper is a review of monopoles, lowest Landau level, fuzzy spheres, and their mutual relations. The Hopf maps of division algebras provide a prototype relation between monopoles and fuzzy spheres. Generalization of complex numbers to Clifford algebra is exactly analogous to generalization of fuzzy two-spheres to higher dimensional fuzzy spheres. Higher dimensional fuzzy spheres have an interesting hierarchical structure made of ''compounds'' of lower dimensional spheres. We give a physical interpretation for such particular structure of fuzzy spheres by utilizing Landau models in generic even dimensions. With Grassmann algebra, we also introduce a graded version of the Hopf map, and discuss its relation to fuzzy supersphere in context of supersymmetric Landau model.
Sample rotating turntable kit for infrared spectrometers
Eckels, Joel Del; Klunder, Gregory L.
2008-03-04
An infrared spectrometer sample rotating turntable kit has a rotatable sample cup containing the sample. The infrared spectrometer has an infrared spectrometer probe for analyzing the sample and the rotatable sample cup is adapted to receive the infrared spectrometer probe. A reflectance standard is located in the rotatable sample cup. A sleeve is positioned proximate the sample cup and adapted to receive the probe. A rotator rotates the rotatable sample cup. A battery is connected to the rotator.
International Nuclear Information System (INIS)
This paper presents a method to reconstruct the absolute shape of a sphere—i.e. a topography of radii—using the sphere interferometer of PTB in combination with a stitching approach. The method allows for the reconstruction of absolute radii instead of the relative shape deviations which result from conventional sphericity measurements. The sphere interferometer was developed for the volume determination of spherical material measures—in particular the spheres of the Avogadro project—by precise diameter measurements with an uncertainty of 1 nm or less. In the scope of the present work a procedure has been implemented that extends the applicability of the interferometer to fields where not the volume or diameter but the direction-dependent radii are of interest. The results of the reconstruction were compared quantitatively to the independent results of sphericity measurements from CSIRO
Lessons learned with the SAGE spectrometer
International Nuclear Information System (INIS)
The SAGE spectrometer combines a high-efficiency γ-ray detection system with an electron spectrometer. Some of the design features have been known to be problematic and surprises have come up during the early implementation of the spectrometer. Tests related to bismuth germanate Compton-suppression shields, electron detection efficiency and an improved cooling system are discussed in the paper. (paper)
Electron spectrometer for gas-phase spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Bozek, J.D.; Schlachter, A.S. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)
1997-04-01
An electron spectrometer for high-resolution spectroscopy of gaseous samples using synchrotron radiation has been designed and constructed. The spectrometer consists of a gas cell, cylindrical electrostatic lens, spherical-sector electron energy analyzer, position-sensitive detector and associated power supplies, electronics and vacuum pumps. Details of the spectrometer design are presented together with some representative spectra.
New schemes of static mass spectrometers
Energy Technology Data Exchange (ETDEWEB)
Baisanov, O.A. [Military Institute of Air Defense Forces, Aktobe (Kazakhstan); Doskeyev, G.A. [Aktobe State University named after K. Zhubanov, Aktobe (Kazakhstan); Spivak-Lavrov, I.F., E-mail: baisanov@mail.ru [Aktobe State University named after K. Zhubanov, Aktobe (Kazakhstan)
2011-07-21
Different possibilities to increase the 'quality', or Q-quantity, of static mass spectrometers by expanding the ion beam before it enters the magnetic field are analyzed. The design of mass spectrometers using a cone-shaped achromatic prism is discussed. Different variants of achromatic mass spectrometers using electrostatic prisms and sector magnetic fields are also considered.
Advanced Mass Spectrometers for Hydrogen Isotope Analyses
Energy Technology Data Exchange (ETDEWEB)
Chastagner, P.
2001-08-01
This report is a summary of the results of a joint Savannah River Laboratory (SRL) - Savannah River Plant (SRP) ''Hydrogen Isotope Mass Spectrometer Evaluation Program''. The program was undertaken to evaluate two prototype hydrogen isotope mass spectrometers and obtain sufficient data to permit SRP personnel to specify the mass spectrometers to replace obsolete instruments.
New schemes of static mass spectrometers
International Nuclear Information System (INIS)
Different possibilities to increase the 'quality', or Q-quantity, of static mass spectrometers by expanding the ion beam before it enters the magnetic field are analyzed. The design of mass spectrometers using a cone-shaped achromatic prism is discussed. Different variants of achromatic mass spectrometers using electrostatic prisms and sector magnetic fields are also considered.
Temporal dispersion of a spectrometer.
Visco, A; Drake, R P; Froula, D H; Glenzer, S H; Pollock, B B
2008-10-01
The temporal dispersion of an optical spectrometer has been characterized for a variety of conditions related to optical diagnostics to be fielded at the National Ignition Facility (e.g., full-aperture backscatter station, Thomson scattering). Significant time smear is introduced into these systems by the path length difference through the spectrometer. The temporal resolution is shown to depend only on the order of the grating, wavelength, and the number of grooves illuminated. To enhance the temporal resolution, the spectral gratings can be masked limiting the number of grooves illuminated. Experiments have been conducted to verify these calculations. The size and shape of masks are investigated and correlated with the exact shape of the temporal instrument function, which is required when interpreting temporally resolved data. The experiments used a 300 fs laser pulse and a picosecond optical streak camera to determine the temporal dispersion. This was done for multiple spectral orders, gratings, and optical masks. PMID:19044687
Temporal Dispersion of a Spectrometer
International Nuclear Information System (INIS)
The temporal dispersion of an optical spectrometer has been characterized for a variety of conditions related to optical diagnostics to be fielded at the National Ignition Facility (e.g., Full-Aperture Backscatter Station, Thomson Scattering). Significant time smear is introduced into these systems by the path length difference through the spectrometer. The temporal resolution can be calculated to depend only on the order of the grating, wavelength, and the number of grooves illuminated. To enhance the temporal dispersion, the spectral gratings can be masked limiting the number of grooves illuminated. Experiments have been conducted to verify these calculations. The size and shape of masks are investigated and correlated to the exact shape of the temporal instrument function, which is required when interpreting temporally resolved data. The experiments used a 300fs laser pulse and a picosecond optical streak camera to determine the temporal dispersion. This was done for multiple spectral orders, gratings, and optical masks
Airborne gamma ray spectrometer surveying
International Nuclear Information System (INIS)
The International Atomic Energy Agency (IAEA) in its role as collector and disseminator of information on nuclear techniques has long had an interest in gamma ray spectrometer methods and has published a number of Technical Reports on various aspects of the subject. At an Advisory Group Meeting held in Vienna in November 1986 to review appropriate activities the IAEA could take following the Chernobyl accident, it was recommended that preparation begin on a new Technical Report on airborne gamma ray spectrometer surveying, taking into account the use of the technique for environmental monitoring as well as for nuclear emergency response requirements. Shortly thereafter the IAEA became the lead organization in the Radioelement Geochemical Mapping section of the International Geological Correlation Programme/United Nations Educational, Scientific and Cultural Organization (UNESCO) Project on International Geochemical Mapping. These two factors led to the preparation of the present Technical Report. 18 figs, 4 tabs
Redding, Brandon; Bromberg, Yaron; Sarma, Raktim; Cao, Hui
2016-01-01
We designed an on-chip spectrometer based on an evanescently-coupled multimode spiral waveguide. Interference between the modes in the waveguide forms a wavelength-dependent speckle pattern which can be used as a fingerprint to identify the input wavelength after calibration. Evanescent coupling between neighboring arms of the spiral enhances the temporal spread of light propagating through the spiral, leading to a dramatic increase in the spectral resolution. Experimentally, we demonstrated that a 250 {\\mu}m radius spiral spectrometer provides a resolution of 0.01 nm at a wavelength of 1520 nm. Spectra containing 40 independent spectral channels can be recovered simultaneously and the operation bandwidth can be increased further when measuring sparse spectra.
Velocity selector for SANS spectrometer
International Nuclear Information System (INIS)
Mechanical velocity selector, designed firstly at the beginning of the neutron age (the end of 40-th - 50-th, see and references herein) are nowadays of wide use at SANS spectrometers on steady state neutron sources. The present report is devoted to the description of the construction and parameters of the selector, designed for SANS spectrometer at the 1 MW research reactor (URGN, Draria, Algeria). The design of selector provides high transmission (more then 90%) and wavelength resolution of Δλ,/λ ∼ 14%, allowing the neutron wavelength to be selected between 4 A and 10 A. The rotor of selector is an aluminium cylinder rotating in a vacuum jacket around the horizontal axis. The rotor slits of helical shape are formed by absorbing plates with thickness 0.5 mm and made of Gd (10%)-Al alloy. (author)
Development of cold neutron spectrometers
International Nuclear Information System (INIS)
□ Cold Neutron Triple Axsis Spectrometer (Cold-TAS) Development Ο Fabrication and Installation of the Major Cold-TAS Components Ο Performance Test of the Cold-TAS □ Cold Neutron Time-of-Flight Spectrometer(DC-TOF) Development Ο Fabrication of the Major DC-TOF Components Ο Development DC-TOF Data Reduction Software □ Expected Contribution The two world-class inelastic neutron scattering instruments measure atomic or molecular scale dynamics of meV energy range. This unprecedented measurement capability in the country will enable domestic and international scientists to observe new phenomena in their materials research to obtain world class results. Especially those who work in the fields of magnetic properties of superconductors and multiferroics, molecular dynamics, etc. will get more benefit from these two instruments
A Double Slow Neutron Spectrometer
International Nuclear Information System (INIS)
The neutron spectrometer described in the paper is intended for measurements of the angular and energy distribution of monochromatic slow neutrons, inelasticaily scattered by liquid and solid bodies. Experiments of this type permit detailed information to be obtained concerning the dynamics of the atoms in various aggregate states of a substance. The spectromeeter is based on the time-of-flight method. The pulse source of neutrons is the IBR (1) reactor. A mechanical interrupter, rotating synchronously with the disc of the IBR and having a prescribed phase shift, serves as the monochromator. A special phasing system ensures a phasee stability better than 0.5o. The neutrons scattered by the sample are recorded by a scintillation detector set at a given angle to the neutron beam. The resolving power of the spectrometer is - 15 μs/m. The paper gives a detailed description of the construction of the spectroscope and its characteristics. (author)
International Nuclear Information System (INIS)
LBL safety policy (Pub 300 Appendix E) states that every research operation with a Class A risk potential (DOE 5484.1) should identify potentially hazardous procedures associated with the operation and develop methods for accomplishing the operation safely without personnel injury or property damage. The rules and practices that management deems to be minimally necessary for the safe operations of the Heavy Ion Spectrometer System (HISS) in the Bevatron Experimental Hall (51B) are set forth in this Operation Safety Procedures
Medium energy charged particle spectrometer
International Nuclear Information System (INIS)
The charged particle spectrometer E8 on HELIOS A and B will be described in some detail. It covers proton energies from 80 keV to 6 MeV, electrons from 20 keV to 2 MeV, and positrons from 150 to 550 keV. Its flight performance will be discussed. From examples of measurements the capability of the instrument will be demonstrated. (orig.)
Very large solid angle spectrometers
International Nuclear Information System (INIS)
The basic conditions of coincidence experiments are discussed and some of the properties of specific detectors covering up to 90% of 4π steradian and presenting a very large momentum bite are shown. It will appear that such detectors, compared to classical iron dipole spectrometers, present larger acceptances, but a smaller resolving power and a rather low background rejection. The choice of which of these two solutions is to be used depends on the conditions of the specific experiments
Fermions, Skyrmions and the 3-sphere
Energy Technology Data Exchange (ETDEWEB)
Goatham, Stephen W; Krusch, Steffen [School of Mathematics, Statistics and Actuarial Science, University of Kent, Canterbury CT2 7NF (United Kingdom)], E-mail: swg3@kent.ac.uk, E-mail: S.Krusch@kent.ac.uk
2010-01-22
This paper investigates a background charge one Skyrme field chirally coupled to light fermions on the 3-sphere. The Dirac equation for the system commutes with a generalized angular momentum or grand spin. It can be solved explicitly for a Skyrme configuration given by the hedgehog form. The energy spectrum and degeneracies are derived for all values of the grand spin. Solutions for non-zero grand spin are each characterized by a set of four polynomials. The paper also discusses the energy of the Dirac sea using zeta-function regularization.
Fermions, Skyrmions and the 3-Sphere
Goatham, Stephen W
2009-01-01
This paper investigates a background charge one Skyrme field chirally coupled to light fermions on the 3-sphere. The Dirac equation for the system commutes with a generalised angular momentum or grand spin. It can be solved explicitly for a Skyrme configuration given by the hedgehog form. The energy spectrum and degeneracies are derived for all values of the grand spin. Solutions for non-zero grand spin are each characterised by a set of four polynomials. The paper also discusses the energy of the Dirac sea using zeta function regularization.
Embeddability in the 3-sphere is decidable
Matoušek, Jiří; Sedgwick, Eric; Tancer, Martin; Wagner, Uli
2014-01-01
We show that the following algorithmic problem is decidable: given a $2$-dimensional simplicial complex, can it be embedded (topologically, or equivalently, piecewise linearly) in $\\mathbf{R}^3$? By a known reduction, it suffices to decide the embeddability of a given triangulated 3-manifold $X$ into the 3-sphere $S^3$. The main step, which allows us to simplify $X$ and recurse, is in proving that if $X$ can be embedded in $S^3$, then there is also an embedding in which $X$ has a short meridi...
Conformally flat anisotropic spheres in general relativity
Herrera, L; Ospina, J F; Fuenmayor, E
2001-01-01
The condition for the vanishing of the Weyl tensor is integrated in the spherically symmetric case. Then, the resulting expression is used to find new, conformally flat, interior solutions to Einstein equations for locally anisotropic fluids. The slow evolution of these models is contrasted with the evolution of models with similar energy density or radial pressure distribution but non-vanishing Weyl tensor, thereby bringing out the different role played by the Weyl tensor, the local anisotropy of pressure and the inhomogeneity of the energy density in the collapse of relativistic spheres.
Sphere impact and penetration into wet sand
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.
The rheology of adhesive hard sphere dispersions
Woutersen, A. T. J. M.; de Kruif, C. G.
1991-04-01
The influence of an attractive interparticle potential on the rheology of a sterically stabilized silica dispersion was investigated. Using a marginal solvent, there was an effective attraction between the particles which depended on the temperature. Three experiments in which different properties of the dispersion were probed showed that a square well model can be used to describe the temperature dependence of the pair potential. The turbidity of a dilute dispersion was measured as a function of the volume fraction and the temperature. Using dynamic light scattering techniques, the effect of the strength of the interparticle attraction on the diffusion coefficient was investigated. Furthermore, the steady shear viscosity was measured as a function of the volume fraction and the temperature. A microscopic theory for the low shear viscosity of a semidilute dispersion of adhesive hard spheres was successfully used to determine the interaction parameters. Viscosity measurement on dense suspensions showed that while the system is still in the one-phase state, temporal aggregates are formed by the interparticle forces which are disrupted by both shear and Brownian motion of the particles. The shear thinning behavior of a concentrated dispersion of adhesive hard spheres scales in a dimensionless shear stress. This group is the ratio of the forces, arising from the shear and the interparticle potential.
Characterizing HR3549B using SPHERE
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...
The quantum Talbot effect on a sphere
Energy Technology Data Exchange (ETDEWEB)
Hannay, J H; Lockwood, Amy [H H Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom)
2008-10-03
Any quantum (Schroedinger) wavefunction on a sphere is necessarily periodic in time. The corresponding statement down one dimension, for a circular line instead, is the quantum version of the 'Talbot effect' for a diffraction grating in paraxial optics (which is fully analogous to quantum mechanics). In the circle case the 'revival' of any initial wavefunction at the period, or 'Talbot time', is accompanied by a kind of partial revival at any rational fraction of the period, increasing in complexity for less simple fractions. In particular, any piecewise constant initial wavefunction is again piecewise constant at such times. By contrast, in the sphere case, the simplest piecewise constant wave, constant on hemispheres is shown not to retain its piecewise constancy at rational fractions of the period, but instead, rather strikingly, to develop infinities at calculable locations. The calculation requires the uniform asymptotic form of the Legendre polynomials together with the Poisson sum formula leading to Gauss sums.
Torsional oscillations of a sphere in a Stokes flow
Box, F; Mullin, T
2014-01-01
The results of an experimental investigation of a sphere performing torsional oscillations in a Stokes flow are presented. A novel experimental set up was developed which enabled the motion of the sphere to be remotely controlled through application of an oscillatory magnetic field. The response of the sphere to the applied field was characterised in terms of the viscous, magnetic and gravitational torques acting on the sphere. A mathematical model of the system was developed and good agreement was found between experimental and theoretical results. The flow resulting from the motion of the sphere was measured and the fluid velocity was found to have an inverse square dependence on radial distance from the sphere. Agreement between measurements and the analytical solution for the fluid velocity indicates that the flow may be considered Stokesian.
Analysis of rainbow scattering by a chiral sphere.
Shang, Qing-Chao; Wu, Zhen-Sen; Qu, Tan; Li, Zheng-Jun; Bai, Lu; Gong, Lei
2013-09-23
Based on the scattering theory of a chiral sphere, rainbow phenomenon of a chiral sphere is numerically analyzed in this paper. For chiral spheres illuminated by a linearly polarized wave, there are three first-order rainbows, with whose rainbow angles varying with the chirality parameter. The spectrum of each rainbow structure is presented and the ripple frequencies are found associated with the size and refractive indices of the chiral sphere. Only two rainbow structures remain when the chiral sphere is illuminated by a circularly polarized plane wave. Finally, the rainbows of chiral spheres with slight chirality parameters are found appearing alternately in E-plane and H-plane with the variation of the chirality. PMID:24104080
Negotiating Islam in Emerging Public Spheres in Contemporary Tajikistan
Nozimova, Shahnoza; Epkenhans, Tim
2013-01-01
Over the past decade, the Internet has emerged as a new public sphere in the Central Asian republic of Tajikistan in particular for negotiating ‘Islam’ – religious belief, practice and morality. Whilst the authoritarian regime severely restricts the ‘traditional’ public spheres, the Internet has proven to be more resilient and elusive to government control. Blocked web pages move to other domains, and, in particular, labour migration has ‘denationalized’ public spheres. Additionally, the Inte...
Random close packing fractions of lognormal distributions of hard spheres
Farr, Robert S.
2013-01-01
We apply a recent one-dimensional algorithm for predicting random close packing fractions of polydisperse hard spheres [Farr and Groot, J. Chem. Phys. 133, 244104 (2009)] to the case of lognormal distributions of sphere sizes and mixtures of such populations. We show that the results compare well to two much slower algorithms for directly simulating spheres in three dimensions, and show that the algorithm is fast enough to tackle inverse problems in particle packing: designing size distributi...
Optimized recentered confidence spheres for the multivariate normal mean
Abeysekera, Waruni; Kabaila, Paul
2014-01-01
Casella and Hwang, 1983, JASA, introduced a broad class of recentered confidence spheres for the mean theta of a multivariate normal distribution with covariance matrix sigma^2 I, for sigma^2 known. Both the center and radius functions of these confidence spheres are flexible functions of the data. For the particular case of confidence spheres centered on the positive-part James-Stein estimator and with radius determined by empirical Bayes considerations, they show numerically that these conf...
Hollow sphere, a flexible multimode Gravitational Wave antenna
Lobo, J. Alberto
2001-01-01
Hollow spheres have the same theoretical capabilities as the usual solid ones, since they share identical symmetries. The hollow sphere is however more flexible, as thickness is an additional parameter one can vary to approach given specifications. I will briefly discuss the more relevant properties of the hollow sphere as a GW detector (frequencies, cross sections), and suggest some scenarios where it can generate significant astrophysical information.
Oil capture from a water surface by a falling sphere
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.
On $k$-stellated and $k$-stacked spheres
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...
CER-MET SPHERE-PAC fuel potential
International Nuclear Information System (INIS)
During operation of the fuel rods in an LWR core the low thermal conductivity of oxide fuel causes high temperatures in the fuel column. This imposes restrictions on the permissible power increases of the fuel rods during in-reactor operation. In a joint KEMA-ECN-GKN programme the applicability of a 3-fraction mixture of large MOX spheres with medium and small natural UO2 spheres in an 88 percent smear density sphere-pac columns of LWR fuel rods has been shown. A 3-fraction CER-MET sphere-pac fuel column of large UO2 or MOX spheres with medium and small spheres of a metal alloy, has a much higher thermal conductivity than pure oxide fuel. Sooner or later uranium becomes scarcer and plutonium from reprocessing plants has to be used in LWR fuel. Then, for CER-MET sphere-pac fuel only 1 fraction has to be fabricated from the plutonium of the reprocessing plants. Moreover, thanks to the low operation temperatures in the CER-MET sphere-pac fuel column the restrictions on power increases become less stringent and the stored heat in the core is lower than in pure oxide cores. The major material aspects of this new CER-MET sphere-pac fuel are presented here. (author). 19 refs.; 7 tabs
Synthesis and Characterization of Oil-Chitosan Composite Spheres
Huang, Keng-Shiang; Wang, Chih-Yu; Yang, Chih-Hui; Grumezescu, Alexandru; Lin, Yung-Sheng; Kung, Chao-Pin; Lin, I-Yin; Chang, Yi-Ching; Weng, Wei-Jie; Wang, Wei-Ting
2013-01-01
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 (ir...
Method and apparatus for producing small hollow spheres
International Nuclear Information System (INIS)
A method and apparatus are described for producing small hollow spheres of glass, metal or plastic, wherein the sphere material is mixed with or contains as part of the composition a blowing agent which decomposes at high temperature (T greater than or equal to 6000C). As the temperature is quickly raised, the blowing agent decomposes and the resulting gas expands from within, thus forming a hollow sphere of controllable thickness. The thus produced hollow spheres (20 to 103 μm) have a variety of application, and are particularly useful in the fabrication of targets for laser implosion such as neutron sources, laser fusion physics studies, and laser initiated fusion power plants
Human postprandial gastric emptying of 1-3-millimeter spheres
International Nuclear Information System (INIS)
Microspheres of pancreatin should empty from the stomachs of patients with pancreatic insufficiency as fast as food. The present study was undertaken in 26 healthy subjects to identify the size of spheres that would empty from the stomach with food and to determine whether different meals alter this size. Spheres of predefined sizes were labeled with /sup 113m/In or /sup 99m/Tc. Using a gamma-camera, we studied the concurrent gastric emptying of spheres labeled with /sup 113m/In and of chicken liver labeled with /sup 99m/Tc in 100-g, 154-kcal or 420-g, 919-kcal meals, or the concurrent emptying of 1-mm vs. larger spheres. One-millimeter spheres emptied consistently (p less than 0.01, paired t-test) faster than 2.4- or 3.2-mm spheres when ingested together with either the 420- or 100-g meals. Thus, in the 1-3-mm range of diameters, sphere size was a more important determinant of sphere emptying than meal size. Statistical analyses indicated that spheres 1.4 +/- 0.3 mm in diameter with a density of 1 empty at the same rate as /sup 99m/Tc-liver. Our data indicate some commercially marketed microspheres of pancreatin will empty too slowly to be effective in digestion of food
IBM WebSphere Application Server 80 Administration Guide
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.
The Pickup Ion Composition Spectrometer
Gilbert, Jason A.; Zurbuchen, Thomas H.; Battel, Steven
2016-06-01
Observations of newly ionized atoms that are picked up by the magnetic field in the expanding solar wind contain crucial information about the gas or dust compositions of their origins. The pickup ions (PUIs) are collected by plasma mass spectrometers and analyzed for their density, composition, and velocity distribution. In addition to measurements of PUIs from planetary sources, in situ measurements of interstellar gas have been made possible by spectrometers capable of differentiating between heavy ions of solar and interstellar origin. While important research has been done on these often singly charged ions, the instruments that have detected many of them were designed for the energy range and ionic charge states of the solar wind and energized particle populations, and not for pickup ions. An instrument optimized for the complete energy and time-of-flight characterization of pickup ions will unlock a wealth of data on these hitherto unobserved or unresolved PUI species. The Pickup Ion Composition Spectrometer (PICSpec) is one such instrument and can enable the next generation of pickup ion and isotopic mass composition measurements. By combining a large-gap time-of-flight-energy sensor with a -100 kV high-voltage power supply for ion acceleration, PUIs will not only be above the detection threshold of traditional solid-state energy detectors but also be resolved sufficiently in time of flight that isotopic composition can be determined. This technology will lead to a new generation of space composition instruments, optimized for measurements of both heliospheric and planetary pickup ions.
The VERDI fission fragment spectrometer
Frégeau M.O.; Bryś T.; Gamboni Th.; Geerts W.; Oberstedt S.; Oberstedt A.; Borcea R.
2013-01-01
The VERDI time-of-flight spectrometer is dedicated to measurements of fission product yields and of prompt neutron emission data. Pre-neutron fission-fragment masses will be determined by the double time-of-flight (TOF) technique. For this purpose an excellent time resolution is required. The time of flight of the fragments will be measured by electrostatic mirrors located near the target and the time signal coming from silicon detectors located at 50 cm on both sides of the target. This conf...
High-Resolution Imaging Spectrometer
Dozier, Jeff; Goetz, Alexander F. H.
1990-01-01
Earth resources observed in greater detail. High-Resolution Imaging Spectrometer, undergoing development for use in NASA's Earth Observing System, measures reflectance of Earth's surface in visible and near-infrared wavelengths. From an orbit around Earth, instrument scans surface of Earth in 200 wavelength bands simultaneously. Produces images enabling identification of minerals in rocks and soils, important algal pigments in oceans and inland waters, changes in spectra associated with biochemistry of plant canopies, compositions of atmospheric aerosols, sizes of grains in snow, and contamination of snow by impurities that absorb visible light.
The Alpha Magnetic Spectrometer (AMS)
Alcaraz, J; Ambrosi, G; Anderhub, H; Ao, L; Arefev, A; Azzarello, P; Babucci, E; Baldini, L; Basile, M; Barancourt, D; Barão, F; Barbier, G; Barreira, G; Battiston, R; Becker, R; Becker, U; Bellagamba, L; Bene, P; Berdugo, J; Berges, P; Bertucci, B; Biland, A; Bizzaglia, S; Blasko, S; Bölla, G; Boschini, M; Bourquin, Maurice; Brocco, L; Bruni, G; Buénerd, M; Burger, J D; Burger, W J; Cai, X D; Camps, C; Cannarsa, P; Capell, M; Casadei, D; Casaus, J; Castellini, G; Cecchi, C; Chang, Y H; Chen, H F; Chen, H S; Chen, Z G; Chernoplekov, N A; Tzi Hong Chiueh; Chuang, Y L; Cindolo, F; Commichau, V; Contin, A; Crespo, P; Cristinziani, M; Cunha, J P D; Dai, T S; Deus, J D; Dinu, N; Djambazov, L; Dantone, I; Dong, Z R; Emonet, P; Engelberg, J; Eppling, F J; Eronen, T; Esposito, G; Extermann, P; Favier, Jean; Fiandrini, E; Fisher, P H; Flügge, G; Fouque, N; Galaktionov, Yu; Gervasi, M; Giusti, P; Grandi, D; Grimm, O; Gu, W Q; Hangarter, K; Hasan, A; Hermel, V; Hofer, H; Huang, M A; Hungerford, W; Ionica, M; Ionica, R; Jongmanns, M; Karlamaa, K; Karpinski, W; Kenney, G; Kenny, J; Kim, W; Klimentov, A; Kossakowski, R; Koutsenko, V F; Kraeber, M; Laborie, G; Laitinen, T; Lamanna, G; Laurenti, G; Lebedev, A; Lee, S C; Levi, G; Levchenko, P M; Liu, C L; Liu, H T; Lopes, I; Lu, G; Lü, Y S; Lübelsmeyer, K; Luckey, D; Lustermann, W; Maña, C; Margotti, A; Mayet, F; McNeil, R R; Meillon, B; Menichelli, M; Mihul, A; Mourao, A; Mujunen, A; Palmonari, F; Papi, A; Park, I H; Pauluzzi, M; Pauss, Felicitas; Perrin, E; Pesci, A; Pevsner, A; Pimenta, M; Plyaskin, V; Pozhidaev, V; Postolache, V; Produit, N; Rancoita, P G; Rapin, D; Raupach, F; Ren, D; Ren, Z; Ribordy, M; Richeux, J P; Riihonen, E; Ritakari, J; Röser, U; Roissin, C; Sagdeev, R; Sartorelli, G; Schwering, G; Scolieri, G; Seo, E S; Shoutko, V; Shoumilov, E; Siedling, R; Son, D; Song, T; Steuer, M; Sun, G S; Suter, H; Tang, X W; Ting, Samuel C C; Ting, S M; Tornikoski, M; Torsti, J; Ulbricht, J; Urpo, S; Usoskin, I; Valtonen, E; Vandenhirtz, J; Velcea, F; Velikhov, E P; Verlaat, B; Vetlitskii, I; Vezzu, F; Vialle, J P; Viertel, Gert M; Vitè, Davide F; Gunten, H V; Wallraff, W; Wang, B C; Wang, J Z; Wang, Y H; Wiik, K; Williams, C; Wu, S X; Xia, P C; Yan, J L; Yan, L G; Yang, C G; Yang, M; Ye, S W; Yeh, P; Xu, Z Z; Zhang, H Y; Zhang, Z P; Zhao, D X; Zhu, G Y; Zhu, W Z; Zhuang, H L; Zichichi, A; Zimmermann, B
2002-01-01
The Alpha Magnetic Spectrometer (AMS) is a large acceptance (0.65 sr m sup 2) detector designed to operate in the International Space Station (ISS) for three years. The purposes of the experiment are to search for cosmic antimatter and dark matter and to study the composition and energy spectrum of the primary cosmic rays. A 'scaled-down' version has been flown on the Space Shuttle Discovery for 10 days in June 1998. The complete AMS is programmed for installation on the ISS in October 2003 for an operational period of 3 yr. This contribution reports on the experimental configuration that will be installed on the ISS.
The Alpha Magnetic Spectrometer (AMS)
International Nuclear Information System (INIS)
The Alpha Magnetic Spectrometer (AMS) is a large acceptance (0.65 sr m2) detector designed to operate in the International Space Station (ISS) for three years. The purposes of the experiment are to search for cosmic antimatter and dark matter and to study the composition and energy spectrum of the primary cosmic rays. A 'scaled-down' version has been flown on the Space Shuttle Discovery for 10 days in June 1998. The complete AMS is programmed for installation on the ISS in October 2003 for an operational period of 3 yr. This contribution reports on the experimental configuration that will be installed on the ISS
The Alpha Magnetic Spectrometer (AMS)
Energy Technology Data Exchange (ETDEWEB)
Alcaraz, J.; Alpat, B.; Ambrosi, G.; Anderhub, H.; Ao, L.; Arefiev, A.; Azzarello, P.; Babucci, E.; Baldini, L.; Basile, M.; Barancourt, D.; Barao, F.; Barbier, G.; Barreira, G.; Battiston, R.; Becker, R.; Becker, U.; Bellagamba, L.; Bene, P.; Berdugo, J.; Berges, P.; Bertucci, B.; Biland, A.; Bizzaglia, S.; Blasko, S.; Boella, G.; Boschini, M.; Bourquin, M.; Brocco, L.; Bruni, G.; Buenerd, M.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Camps, C.; Cannarsa, P.; Capell, M.; Casadei, D.; Casaus, J.; Castellini, G.; Cecchi, C.; Chang, Y.H.; Chen, H.F.; Chen, H.S.; Chen, Z.G.; Chernoplekov, N.A.; Chiueh, T.H.; Chuang, Y.L.; Cindolo, F.; Commichau, V.; Contin, A. E-mail: contin@bo.infn.it; Crespo, P.; Cristinziani, M.; Cunha, J.P. da; Dai, T.S.; Deus, J.D.; Dinu, N.; Djambazov, L.; DAntone, I.; Dong, Z.R.; Emonet, P.; Engelberg, J.; Eppling, F.J.; Eronen, T.; Esposito, G.; Extermann, P.; Favier, J.; Fiandrini, E.; Fisher, P.H.; Fluegge, G.; Fouque, N.; Galaktionov, Yu.; Gervasi, M.; Giusti, P.; Grandi, D.; Grimm, O.; Gu, W.Q.; Hangarter, K.; Hasan, A.; Hermel, V.; Hofer, H.; Huang, M.A.; Hungerford, W.; Ionica, M.; Ionica, R.; Jongmanns, M.; Karlamaa, K.; Karpinski, W.; Kenney, G.; Kenny, J.; Kim, W.; Klimentov, A.; Kossakowski, R.; Koutsenko, V.; Kraeber, M.; Laborie, G.; Laitinen, T.; Lamanna, G.; Laurenti, G.; Lebedev, A.; Lee, S.C.; Levi, G.; Levtchenko, P.; Liu, C.L.; Liu, H.T.; Lopes, I.; Lu, G.; Lu, Y.S.; Luebelsmeyer, K.; Luckey, D.; Lustermann, W.; Mana, C.; Margotti, A.; Mayet, F.; McNeil, R.R.; Meillon, B.; Menichelli, M.; Mihul, A.; Mourao, A.; Mujunen, A.; Palmonari, F.; Papi, A.; Park, I.H.; Pauluzzi, M.; Pauss, F.; Perrin, E.; Pesci, A.; Pevsner, A.; Pimenta, M.; Plyaskin, V.; Pojidaev, V.; Postolache, V.; Produit, N.; Rancoita, P.G.; Rapin, D.; Raupach, F.; Ren, D.; Ren, Z.; Ribordy, M.; Richeux, J.P.; Riihonen, E.; Ritakari, J.; Roeser, U.; Roissin, C.; Sagdeev, R.; Sartorelli, G.; Schultz von Dratzig, A.; Schwering, G.; Scolieri, G.; Seo, E.S.; Shoutko, V.
2002-02-01
The Alpha Magnetic Spectrometer (AMS) is a large acceptance (0.65 sr m{sup 2}) detector designed to operate in the International Space Station (ISS) for three years. The purposes of the experiment are to search for cosmic antimatter and dark matter and to study the composition and energy spectrum of the primary cosmic rays. A 'scaled-down' version has been flown on the Space Shuttle Discovery for 10 days in June 1998. The complete AMS is programmed for installation on the ISS in October 2003 for an operational period of 3 yr. This contribution reports on the experimental configuration that will be installed on the ISS.
Energy Technology Data Exchange (ETDEWEB)
Patrinoiu, Greta; Calderón-Moreno, Jose Maria; Culita, Daniela C. [Illie Murgulescu Institute of Physical Chemistry, Romanian Academy, Splaiul Independentei 202, 060021 Bucharest (Romania); Birjega, Ruxandra [National Institute for Lasers, Plasma and Radiation Physics, P.O. Box Mg—27, Magurele, Bucharest (Romania); Ene, Ramona [Ilie Murgulescu Institute of Physical Chemistry, Romanian Academy, Splaiul Independentei 202, 060021 Bucharest (Romania); Carp, Oana, E-mail: ocarp@icf.ro [Ilie Murgulescu Institute of Physical Chemistry, Romanian Academy, Splaiul Independentei 202, 060021 Bucharest (Romania)
2013-06-15
A green template route for the synthesis of mesoscale solid ZnO spheres was ascertained. The protocol involves a double coating of the carbonaceous spheres with successive layers of zinc-containing species by alternating a non-ultrasound and ultrasound-assisted deposition, followed by calcination treatments. The composites were characterized by FTIR spectroscopy, thermal analysis, scanning electron microscopy while the obtained ZnO spheres by X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopy, N{sub 2} adsorption–desorption isotherms and photoluminescence investigations. A growth mechanism of the solid spheres is advanced based on these results. While the spheres' diameters and the mean size values of ZnO are independent on deposition order, the surface area and the external porosity are fairly dependent. The photoluminescence measurements showed interesting emission features, with emission bands in the violet to orange region. The spheres present high photocatalytical activity towards the degradation of phenol under UV irradiation, the main reaction being its mineralization. - Graphical abstract: A novel and eco-friendly methodology for the synthesis of mesoscale solid ZnO spheres was developed. The protocol involves a double coating of the starch-derived carbonaceous spheres with successive layers of zinc-containing species by alternating a non-ultrasound and ultrasound-assisted deposition, followed by calcination treatments. - Highlights: • ZnO solid spheres are obtained via a template route using carbonaceous spheres. • Two-step coatings of interchangeable order are used as deposition procedure. • The coating procedure influences the porosity and surface area. • ZnO spheres exhibited interesting visible photoluminescence properties. • Solid spheres showed photocatalytical activity in degradation of phenol.
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, 11, 12, 13, 14, 15, and 20 beads is carried out. The phase behavior of partially flexible fluids with a total length of 8, 10, 14, and 15 beads and with different lengths for the linear part is als...
Institute of Scientific and Technical Information of China (English)
兰明建; 程发银
2009-01-01
将Parikh-Wilczek的半经典隧穿方法推广到动态Vaidya-Bonner黑洞.注意到Hawking辐射是黑洞事件视界附近由于真空涨落而引发的一种量子隧穿,在考虑辐射粒子自引力作用的情况下,计算了粒子的隧穿率及其相应的出射修正谱,结果满足量子理论的幺正性定理.%We extend Parikh and Wilczek's work to the Vaidya-Bonner black hole. We regard Hawking radiation as a tunneling process across the event horizon and calculate the tunneling probability when self-gravi-tation is taken into account. We also obtain the corresponding emission spectrum correction, the result is consist-ent with an underlying unitary theory.
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...
Modelling Priorities of Financial Provision of the Social Sphere
Directory of Open Access Journals (Sweden)
Mamonova Hanna V.
2014-01-01
Full Text Available The article studies the modern state of the social sphere and conducts modelling of priorities of financial provision of the social sphere at the state level. Social sphere should be considered as the basis of development of the national economy. The goal of this article is the study of the modern state and modelling priorities of financial provision of the social sphere at the state level. The subject of the study is modelling priority directions of financial provision of components of the social sphere. Taking into account fast changes in the social sphere of the country and regular increase of social standards, the article identifies a necessity of changing priorities of the social policy, first of all, problems of financing the social sphere and formation of priority directions on improvement of this system. The article shows that the main problems of financial provision of the social sphere are: insufficient volumes of budget funds for financing the social sphere, financing practically all items of social expenditures in a smaller volume than it is required for the existing social support of the population and absence of mechanisms of ensuring quality of social services. The article offers to use the hierarchy analysis method for identifying immediate and priority directions of financing components of the social sphere. On the basis of the built directed communication graph the article presents a binary matrix of dependence of components of the social sphere and builds a hierarchy model of these components. As a result it is seen that the highest level of hierarchy is taken by science, then healthcare and social sphere are at the same level, then education, sports and at the lowest level are culture and art. The obtained results could be used when improving financing of the social sphere. In order to ensure efficiency of functioning of the social sphere it is necessary to improve the system of financing of its components on the basis of use
Polyethylene-reflected plutonium metal sphere : subcritical neutron and gamma measurements.
Energy Technology Data Exchange (ETDEWEB)
Mattingly, John K.
2009-11-01
Numerous benchmark measurements have been performed to enable developers of neutron transport models and codes to evaluate the accuracy of their calculations. In particular, for criticality safety applications, the International Criticality Safety Benchmark Experiment Program (ICSBEP) annually publishes a handbook of critical and subcritical benchmarks. Relatively fewer benchmark measurements have been performed to validate photon transport models and codes, and unlike the ICSBEP, there is no program dedicated to the evaluation and publication of photon benchmarks. Even fewer coupled neutron-photon benchmarks have been performed. This report documents a coupled neutron-photon benchmark for plutonium metal reflected by polyethylene. A 4.5-kg sphere of ?-phase, weapons-grade plutonium metal was measured in six reflected configurations: (1) Bare; (2) Reflected by 0.5 inch of high density polyethylene (HDPE); (3) Reflected by 1.0 inch of HDPE; (4) Reflected by 1.5 inches of HDPE; (5) Reflected by 3.0 inches of HDPE; and (6) Reflected by 6.0 inches of HDPE. Neutron and photon emissions from the plutonium sphere were measured using three instruments: (1) A gross neutron counter; (2) A neutron multiplicity counter; and (3) A high-resolution gamma spectrometer. This report documents the experimental conditions and results in detail sufficient to permit developers of radiation transport models and codes to construct models of the experiments and to compare their calculations to the measurements. All of the data acquired during this series of experiments are available upon request.
Unit quaternions and the Bloch sphere
International Nuclear Information System (INIS)
The spinor representation of spin-1/2 states can equally well be mapped to a single unit quaternion, yielding a new perspective despite the equivalent mathematics. This paper first demonstrates a useable map that allows Bloch-sphere rotations to be represented as quaternionic multiplications, simplifying the form of the dynamical equations. Left-multiplications generally correspond to non-unitary transformations, providing a simpler (essentially classical) analysis of time-reversal. But the quaternion viewpoint also reveals a surprisingly large broken symmetry, as well as a potential way to restore it, via a natural expansion of the state space that has parallels to second order fermions. This expansion to ‘second order qubits’ would imply either a larger gauge freedom or a natural space of hidden variables. (paper)
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.
Particle tracks fitted on the Riemann sphere
Strandlie, A; Frühwirth, R; Lillekjendlie, B
2000-01-01
We present a novel method of fitting trajectories of charged particles in high-energy physics particle detectors. The method fits a circular arc to two-dimensional measurements by mapping the measurements onto the Riemann sphere and fitting a plane to the transformed coordinates of the measurements. In this way, the non- linear task of circle fitting, which in general requires the application of some iterative procedure, is turned into a linear problem which can be solved in a fast, direct and non-iterative manner. We illustrate the usefulness of our approach by stating results from two simulation experiments of tracks from the ATLAS Inner Detector Transition Radiation Tracker (TRT). The first experiment shows that with a significantly lower execution time, the accuracy of the estimated track parameters is virtually as good as the accuracy obtained by applying an optimal, non-linear least- squares procedure. The second experiment focuses on track parameter estimation in the presence of ambiguous measurements....
Algorithmic construction of static perfect fluid spheres
International Nuclear Information System (INIS)
Perfect fluid spheres, either Newtonian or relativistic, are the first step in developing realistic stellar models (or models for fluid planets). Despite the importance of these models, explicit and fully general solutions of the perfect fluid constraint in general relativity have only very recently been developed. In this paper we present a variant of Lake's algorithm wherein (1) we recast the algorithm in terms of variables with a clear physical meaning--the average density and the locally measured acceleration due to gravity, (2) we present explicit and fully general formulas for the mass profile and pressure profile, and (3) we present an explicit closed-form expression for the central pressure. Furthermore we can then use the formalism to easily understand the pattern of interrelationships among many of the previously known exact solutions, and generate several new exact solutions
Perfect fluid spheres in general relativity
International Nuclear Information System (INIS)
Spherically symmetric perfect fluid distributions in general relativity have been investigated under the assumptions of (i) uniform expansion or contraction and (ii) the validity of an equation of state of the form p=p(rho) with nonuniform density. An exact solution which is equivalent to a solution found earlier by Wyman is obtained and it is shown that the solution is unique. The boundary conditions at the interface of fluid distribution and the exterior vacuum are discussed and as a consequence the following theorem is established: Uniform expansion or contraction of a perfect fluid sphere obeying an equation of state with nonuniform density is not admitted by the field equations. It is further shown that the Wyman metric is not suitable on physical grounds to represent a cosmological solution. (author)
Unit quaternions and the Bloch sphere
Wharton, K. B.; Koch, D.
2015-06-01
The spinor representation of spin-1/2 states can equally well be mapped to a single unit quaternion, yielding a new perspective despite the equivalent mathematics. This paper first demonstrates a useable map that allows Bloch-sphere rotations to be represented as quaternionic multiplications, simplifying the form of the dynamical equations. Left-multiplications generally correspond to non-unitary transformations, providing a simpler (essentially classical) analysis of time-reversal. But the quaternion viewpoint also reveals a surprisingly large broken symmetry, as well as a potential way to restore it, via a natural expansion of the state space that has parallels to second order fermions. This expansion to ‘second order qubits’ would imply either a larger gauge freedom or a natural space of hidden variables.
Photonic bandgap fiber bundle spectrometer
Hang, Qu; Syed, Imran; Guo, Ning; Skorobogatiy, Maksim
2010-01-01
We experimentally demonstrate an all-fiber spectrometer consisting of a photonic bandgap fiber bundle and a black and white CCD camera. Photonic crystal fibers used in this work are the large solid core all-plastic Bragg fibers designed for operation in the visible spectral range and featuring bandgaps of 60nm - 180nm-wide. 100 Bragg fibers were chosen to have complimentary and partially overlapping bandgaps covering a 400nm-840nm spectral range. The fiber bundle used in our work is equivalent in its function to a set of 100 optical filters densely packed in the area of ~1cm2. Black and white CCD camera is then used to capture spectrally "binned" image of the incoming light at the output facet of a fiber bundle. To reconstruct the test spectrum from a single CCD image we developed an algorithm based on pseudo-inversion of the spectrometer transmission matrix. We then study resolution limit of this spectroscopic system by testing its performance using spectrally narrow test peaks (FWHM 5nm-25nm) centered at va...
Characteristics of the GALLEX spectrometer
International Nuclear Information System (INIS)
A description is given of the spectrometer used for the detection of 71Ge in the Solar Neutrino experiment GALLEX being performed in the Gran Sasso Underground Laboratory. The spectrometer consists of miniaturized proportional counters and a shield with a large well-type NaI pair (Tl) detector (active side) and an inner pure copper shield (passive side). Very careful material selection for the proportional counter- and shield-construction and radon suppression resulted in total background rates (>0.5 keV) between 0.4 and 1 count per day for many proportional counters. With energy and rise time cuts, the average rates for the relevant L- and K-peak of the 71Ge spectrum are 0.1 cpd and 0.03 cpd, respectively, and thus, are far below the signal predicted by the Standard Solar Model. Eight counter positions within the NaI pair detector have the option to detect also 69Ge and 68Ga (positron emitteres) in the coincidence mode, though with slightly higher background for the 71Ge decay mode. An analysis of the different background components cannot fully account for the measured background of the proportional counters so that presumably a part of it is due to contamination during the assembling process. Here is a potential for further background reduction. After introduction, the basic concept of the experiment and the present status as of December 1991 are briefly outlined. (orig.)
Digital Spectrometers for Interplanetary Science Missions
Jarnot, Robert F.; Padmanabhan, Sharmila; Raffanti, Richard; Richards, Brian; Stek, Paul; Werthimer, Dan; Nikolic, Borivoje
2010-01-01
A fully digital polyphase spectrometer recently developed by the University of California Berkeley Wireless Research Center in conjunction with the Jet Propulsion Laboratory provides a low mass, power, and cost implementation of a spectrum channelizer for submillimeter spectrometers for future missions to the Inner and Outer Solar System. The digital polyphase filter bank spectrometer (PFB) offers broad bandwidth with high spectral resolution, minimal channel-to-channel overlap, and high out-of-band rejection.
Social Justice and Education in the Public and Private Spheres
Power, Sally; Taylor, Chris
2013-01-01
This paper explores the complex relationship between social justice and education in the public and private spheres. The politics of education is often presented as a battle between left and right, the state and the market. In this representation, the public and the private spheres are neatly aligned on either side of the line of battle, and…
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.
Administrative Methods of State Management in the Sphere of Customs
Мартюшевская, Елена Николаевна
2015-01-01
The article dedicates administrative methods of public administration in sphere of customs matters. The author pays attention on the definition of non-tariff measures with regard to non-tariff methods, also how to improve in existing science of classification of administrative methods of public administration in sphere of customs matters.
Computational Analysis of Wake Field Flow between Multiple Identical Spheres
Brand, Wesley; Greenslit, Morton; Klassen, Zach; Hastings, Jay; Matson, William
2014-11-01
It is well understood both that objects moving through a fluid perturb the motion of nearby objects in the same fluid and that some configurations of objects moving through a fluid have little inter-object perturbation, such as a flock of birds flying in a V-formation. However, there is presently no known method for predicting what configurations of objects will be stable while moving through a fluid. Previous work has failed to find such stable configurations because of the computational complexity of finding individual solutions. In this research, the motions of two spheres in water were simulated and combinations of those simulations were used to extrapolate the motions of multiple spheres and to find configurations where the lateral forces on each sphere were negligible and the vertical forces on each sphere were equivalent. Two and three sphere arrangements were simulated in COMSOL Multiphysics and Mathematica was used both to demonstrate that combinations of two sphere cases are identical to three sphere cases and to identify stable configurations of three or more spheres. This new approach is expected to simplify optimization of aerodynamic configurations and applications such as naval and aerospace architecture and racecar driving. Advisor.
Thermodynamic signature of the dynamic glass transition in hard spheres
Hermes, M; Dijkstra, M.
2010-01-01
We use extensive event-driven molecular dynamics simulations to study the thermodynamic, structural and dynamic properties of hard-sphere glasses. We determine the equation of state of the metastable fluid branch for hard spheres with a size polydispersity of 10%. Our results show a clear jump in th
Radioactive spheres without inactive wall for lesion simulation in PET
Energy Technology Data Exchange (ETDEWEB)
Bazanez-Borgert, M.; Bundschuh, R.A.; Herz, M.; Martinez, M.J.; Schwaiger, M.; Ziegler, S.I. [Klinik und Poliklinik fuer Nuklearmedizin, Klinikum rechts der Isar der Technischen Univ. Muenchen (Germany)
2008-07-01
With the growing importance of PET and PET/CT in diagnosis, staging, therapy monitoring and radiotherapy planning, appropriate tools to simulate lesions in phantoms are important. Normally hollow spheres, made of plastic or glass, which can be filled with radioactive solutions, are used. As these spheres have an inactive wall they do not reflect the real situation in the patient and lead to quantification errors in the presence of background activity. We propose spheres made of radioactive wax, which are easy to produce, give a high flexibility to the user and a more accurate quantification. These wax spheres were evaluated for their applicability in PET phantoms and it was found that the activity is not diffusing into the surrounding water in relevant quantities, that they show a sufficient homogeneity, and that their attenuation properties are equivalent to water for photons of PET energies. Recovery coefficients for the wax spheres were measured and compared with those obtained for fillable plastic spheres for diameters of 28, 16, 10, and 6 mm in the presence of background activity. Recovery coefficients of the wax spheres were found to be up to 21% higher than for the fillable spheres. (orig.)
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.
Regions of attraction between like-charged conducting spheres
Lekner, John
2016-06-01
Two positively charged conducting spheres have been shown to attract at close enough range, unless they have a charge ratio that would result from contact. We give analytical results for the charge ratio at which the cross-over between electrostatic attraction and repulsion occurs, as a function of the sphere separation.
Maximum absorption by homogeneous magneto-dielectric sphere
DEFF Research Database (Denmark)
Palvig, Michael Forum; Breinbjerg, Olav; Willatzen, Morten
2014-01-01
n order to obtain a benchmark for electromagnetic energy harvesting, we investigate the maximum absorption efficiency by a magneto-dielectric homogeneous sphere illuminated by a plane wave, and we arrive at several novel results. For electrically small spheres we show that the optimal relative......–Mie theory combined with the optical theorem....
Meteor ablation spheres from deep-sea sediments
Blanchard, M. B.; Brownlee, D. E.; Bunch, T. E.; Hodge, P. W.; Kyte, F. T.
1978-01-01
Spheres from mid-Pacific abyssal clays (0 to 500,000 yrs old), formed from particles that completely melted and subsequently recrystallized as they separated from their meteoroid bodies, or containing relict grains of parent meteoroids that did not experience any melting were analyzed. The spheres were readily divided into three groups using their dominant mineralogy. The Fe-rich spheres were produced during ablation of Fe and metal-rich silicate meteoroids. The glassy spheres are considerably more Fe-rich than the silicate spheres. They consist of magnetite and an Fe glass which is relatively low in Si. Bulk compositions and relict grains are useful for determining the parent meteoroid types for the silicate spheres. Bulk analyses of recrystallized spheres show that nonvolatile elemental abundances are similar to chondrite abundances. Analysis of relict grains identified high temperature minerals associated with a fine-grained, low temperature, volatile-rich matrix. The obvious candidates for parent meteoroids of this type of silicate sphere is a carbonaceous chondrite.
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....
Mesoscale assembly of NiO nanosheets into spheres
International Nuclear Information System (INIS)
NiO solid/hollow spheres with diameters about 100 nm have been successfully synthesized through thermal decomposition of nickel acetate in ethylene glycol at 200 deg. C. These spheres are composed of nanosheets about 3-5 nm thick. Introducing poly(vinyl pyrrolidone) (PVP) surfactant to reaction system can effectively control the products' morphology. By adjusting the quantity of PVP, we accomplish surface areas-tunable NiO assembled spheres from ∼70 to ∼200 m2 g-1. Electrochemical tests show that NiO hollow spheres deliver a large discharge capacity of 823 mA h g-1. Furthermore, these hollow spheres also display a slow capacity-fading rate. A series of contrastive experiments demonstrate that the surface area of NiO assembled spheres has a noticeable influence on their discharge capacity. - Graphical abstract: The mesoscale assembly of NiO nanosheets into spheres have been achieved by a solvothermal method. N2 adsorption/desorption isotherms show the SBET of NiO is tunable. NiO spheres show large discharge capacity and slow capacity-fading rate.
Free motion on the Poisson plane and sphere
Zakrzewski, S.
1996-01-01
Poisson plane and sphere --- homogeneous spaces of Poisson groups E(2) and SU(2) (resp.) --- have phase spaces (corresponding symplectic groupoids), in which a free Hamiltonian is naturally defined. We solve the equations of motion and point out some unexpected features: free motion on the plane is bounded (periodic) and free trajectories on the sphere are all circles except the big ones.
Actions of SL(n,Z) on homology spheres
Parwani, Kamlesh
2005-01-01
Any continuous action of SL(n,Z), where n > 2, on a r-dimensional mod 2 homology sphere factors through a finite group action if r < n - 1. In particular, any continuous action of SL(n+2,Z) on the n-dimensional sphere factors through a finite group action.
Seeded Synthesis of Monodisperse Core-Shell and Hollow Carbon Spheres.
Gil-Herrera, Luz Karime; Blanco, Álvaro; Juárez, Beatriz H; López, Cefe
2016-08-01
Monodisperse carbon spheres between 500 and 900 nm are hydrothermally synthesized from glucose on polystyrene seeds. Control over temperature, time, glucose concentration, and seed size yields hybrid spheres without aggregation and no additional spheres population. Pyrolysis transforms the hybrid into hollow carbon spheres preserving monodispersity. This approach provides a basis for functional carbon spheres applicable in photonics and energy storage. PMID:27337299
Neutron spectrometry using artificial neural networks
International Nuclear Information System (INIS)
An artificial neural network has been designed to obtain neutron spectra from Bonner spheres spectrometer count rates. The neural network was trained using 129 neutron spectra. These include spectra from isotopic neutron sources; reference and operational spectra from accelerators and nuclear reactors, spectra based on mathematical functions as well as few energy groups and monoenergetic spectra. The spectra were transformed from lethargy to energy distribution and were re-binned to 31 energy groups using the MCNP 4C code. The re-binned spectra and the UTA4 response matrix were used to calculate the expected count rates in Bonner spheres spectrometer. These count rates were used as input and their respective spectra were used as output during the neural network training. After training, the network was tested with the Bonner spheres count rates produced by folding a set of neutron spectra with the response matrix. This set contains data used during network training as well as data not used. Training and testing was carried out using the Matlab(R) program. To verify the network unfolding performance, the original and unfolded spectra were compared using the root mean square error. The use of artificial neural networks to unfold neutron spectra in neutron spectrometry is an alternative procedure that overcomes the drawbacks associated with this ill-conditioned problem
Neutron spectrometry with artificial neural networks
International Nuclear Information System (INIS)
An artificial neural network has been designed to obtain the neutron spectra from the Bonner spheres spectrometer's count rates. The neural network was trained using 129 neutron spectra. These include isotopic neutron sources; reference and operational spectra from accelerators and nuclear reactors, spectra from mathematical functions as well as few energy groups and monoenergetic spectra. The spectra were transformed from lethargy to energy distribution and were re-bin ned to 31 energy groups using the MCNP 4C code. Re-binned spectra and UTA4 response matrix were used to calculate the expected count rates in Bonner spheres spectrometer. These count rates were used as input and the respective spectrum was used as output during neural network training. After training the network was tested with the Bonner spheres count rates produced by a set of neutron spectra. This set contains data used during network training as well as data not used. Training and testing was carried out in the Mat lab program. To verify the network unfolding performance the original and unfolded spectra were compared using the χ2-test and the total fluence ratios. The use of Artificial Neural Networks to unfold neutron spectra in neutron spectrometry is an alternative procedure that overcomes the drawbacks associated in this ill-conditioned problem. (Author)
Oyarzún, Bernardo; van Westen, Thijs; Vlugt, Thijs J. H.
2013-05-01
The 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, 11, 12, 13, 14, 15, and 20 beads is carried out. The phase behavior of partially flexible fluids with a total length of 8, 10, 14, and 15 beads and with different lengths for the linear part is also determined. A precise description of the reduced pressure and of the packing fraction change at the isotropic-nematic coexistence was achieved by performing long simulation runs. For linear fluids, a maximum in the isotropic to nematic packing fraction change is observed for a chain length of 15 beads. The infinite dilution solubility of hard spheres in linear and partially flexible hard-sphere chain fluids is calculated by the Widom test-particle insertion method. To identify the effect of chain connectivity and molecular anisotropy on free volume, solubility is expressed relative to that of hard spheres in a hard sphere fluid at same packing fraction as relative Henry's law constants. A linear relationship between relative Henry's law constants and packing fraction is observed for all linear fluids. Furthermore, this linearity is independent of liquid crystal ordering and seems to be independent of chain length for linear chains of 10 beads and longer. The same linear relationship was observed for the solubility of hard spheres in nematic forming partially flexible fluids for packing fractions up to a value slightly higher than the nematic packing fraction at the isotropic-nematic coexistence. At higher packing fractions, the small flexibility of these fluids seems to improve solubility in comparison with the linear fluids.
Sampling theorems and compressive sensing on the sphere
McEwen, J D; Thiran, J -Ph; Vandergheynst, P; Van De Ville, D; Wiaux, Y
2011-01-01
We discuss a novel sampling theorem on the sphere developed by McEwen & Wiaux recently through an association between the sphere and the torus. To represent a band-limited signal exactly, this new sampling theorem requires less than half the number of samples of other equiangular sampling theorems on the sphere, such as the canonical Driscoll & Healy sampling theorem. A reduction in the number of samples required to represent a band-limited signal on the sphere has important implications for compressive sensing, both in terms of the dimensionality and sparsity of signals. We illustrate the impact of this property with an inpainting problem on the sphere, where we show superior reconstruction performance when adopting the new sampling theorem.
Quantum states of two particles on concentric spheres
Ezra, Gregory S.; Berry, R. Stephen
1983-10-01
The model of two particles on a sphere is extended to two particles on concentric spheres (POCS). The quantum states are found for two electrons, one on a sphere of radius 10 a.u. (simulating the shell n=3 in He) and the other, on spheres of 10, 15, 25, 50, and 100 a.u. The eigenvalues and densities ρ(θ12) exhibit a transition from collective, moleculelike behavior to independent-particle-like behavior with Russell-Saunders coupling. The parallel problem of two particles with electron masses interacting via a repulsive Gaussian potential is also treated and a similar transition from collective to independent-particle behavior found. The principal difference between the two cases is only the region of radius of the larger sphere where the transition occurs.
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.
An integrating sphere to measure CD from difficult samples
Castiglioni; Albertini
2000-05-01
Integrating spheres are widely used with UV-Vis and occasionally with infrared spectrophotometers to measure different types of samples, either in transmission mode (scattered transmission accessories) or in total/diffuse reflectance mode. We built a prototype sphere of the demountable type, which fits easily the sample compartment of a commercial CD spectropolarimeter, requiring neither any alignment nor the use of a dedicated photomultiplier. Samples can be inserted either at the sphere entrance (for scattered transmission mode) or in the center of the sphere (for total reflectance experiments). Selected experimental data are presented to evaluate sphere efficiency, its wavelength range and results with a single sample in different forms. Copyright 2000 Wiley-Liss, Inc. PMID:10790200
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.
SPHERE: a scalable multicast framework in overlay networks
Institute of Scientific and Technical Information of China (English)
无
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.
Fabrication of beryllium spheres and its validation tests
International Nuclear Information System (INIS)
A sphere-pack blanket concept using small size spheres of beryllium is one of the promising design concept of the ITER blanket, because the sphere-pack can accommodate the size deformation due to neutron irradiation damage, helium swelling and cyclic temperature changes. Preliminary R and D for an industrial fabrication technology of beryllium spheres (1.0 ± 0.3 mm in diameter) has been started as part of feasibility study of Japanese blanket concept of layered sphere-pack configuration. The following tests were performed in the several demo-fabrications; feasibility of size distribution control, material characterization such as macroscopic and microscopic structure analysis, impurity analysis, and attainable packing density, mechanical integrity under various thermal cycling conditions. (author)
Buchillier, T; Aroua, A; Bochud, F O
2007-01-01
Spectrometric and dosimetric measurements were made around a cask containing spent fuel and a cask containing high-level radioactive waste at the Swiss intermediate waste and spent fuel storage facility. A Bonner sphere spectrometer, an LB 6411 neutron monitor and an Automess Szintomat 6134A were used to characterise the n-gamma fields at several locations around the two casks. The results of these measurements show that the neutron fluence spectra around the cask containing radioactive waste are harder and higher in intensity than those measured in the vicinity of the spent fuel cask. The ambient dose equivalents measured with the LB 6411 neutron monitor are in good agreement with those obtained using the Bonner spheres, except for locations with soft neutron spectra where the monitor overestimates the neutron ambient dose equivalent by almost 50%. PMID:17494980
A computer controlled Moessbauer spectrometer
International Nuclear Information System (INIS)
This paper describes a computer controlled data acquisition system for Moessbauer spectroscopy. In addition to reporting the fundamental ideas behind, and the construction of the system, this paper intends to serve as a manual for the user. The main unit is the 'Mark-VII' multiscaler/function generator, constructed as a double width NIM-unit. For the control of this unit we use an Apple IIe++ microcomputer equipped with a specially designed interface 'Kart-7'. The information supplied here should, however, be sufficient to interface other suitable microcomputers to the Mark-VII unit. The Kart-7 interface is described in this paper together with some details concerning its programming. The system is controlled by a program called 'HIN-5', which is also described in some detail. The manual section gives the details of how to start up and operate the spectrometer. (author)
Multimode optical fiber based spectrometers
Redding, Brandon; Cao, Hui
2013-01-01
A standard multimode optical fiber can be used as a general purpose spectrometer after calibrating the wavelength dependent speckle patterns produced by interference between the guided modes of the fiber. A transmission matrix was used to store the calibration data and a robust algorithm was developed to reconstruct an arbitrary input spectrum in the presence of experimental noise. We demonstrate that a 20 meter long fiber can resolve two laser lines separated by only 8 pm. At the other extreme, we show that a 2 centimeter long fiber can measure a broadband continuous spectrum generated from a supercontinuum source. We investigate the effect of the fiber geometry on the spectral resolution and bandwidth, and also discuss the additional limitation on the bandwidth imposed by speckle contrast reduction when measuring dense spectra. Finally, we demonstrate a method to reduce the spectrum reconstruction error and increase the bandwidth by separately imaging the speckle patterns of orthogonal polarizations. The mu...
Neutron measurement by transportable spectrometer
International Nuclear Information System (INIS)
Two levels of neutron spectrometry are in regular use at nuclear power plants: some techniques used in the laboratory produce detailed spectra but require specialist operators, while simple instruments used by non-specialists to measure the neutron dose-rate to operators provide little spectral information. The standard portable instruments are therefore of no use when anomalous readings are obtained which require further investigation. AEA Technology at Winfrith has developed a Transportable Neutron Spectrometer (TNS) which is designed to produce reasonable spectra in routine use by staff with no specialist skill in spectroscopy, and high-quality spectra in the hands of skilled staff. The TNS provides a level of information intermediate between those currently available, and is also designed to solve the problem of imperfect dose response which is common in portable dosimeters. The TNS system consists of a power supply, a probe and a signal processing and data acquisition unit. (author)
A colloidal quantum dot spectrometer
Bao, Jie; Bawendi, Moungi G.
2015-07-01
Spectroscopy is carried out in almost every field of science, whenever light interacts with matter. Although sophisticated instruments with impressive performance characteristics are available, much effort continues to be invested in the development of miniaturized, cheap and easy-to-use systems. Current microspectrometer designs mostly use interference filters and interferometric optics that limit their photon efficiency, resolution and spectral range. Here we show that many of these limitations can be overcome by replacing interferometric optics with a two-dimensional absorptive filter array composed of colloidal quantum dots. Instead of measuring different bands of a spectrum individually after introducing temporal or spatial separations with gratings or interference-based narrowband filters, a colloidal quantum dot spectrometer measures a light spectrum based on the wavelength multiplexing principle: multiple spectral bands are encoded and detected simultaneously with one filter and one detector, respectively, with the array format allowing the process to be efficiently repeated many times using different filters with different encoding so that sufficient information is obtained to enable computational reconstruction of the target spectrum. We illustrate the performance of such a quantum dot microspectrometer, made from 195 different types of quantum dots with absorption features that cover a spectral range of 300 nanometres, by measuring shifts in spectral peak positions as small as one nanometre. Given this performance, demonstrable avenues for further improvement, the ease with which quantum dots can be processed and integrated, and their numerous finely tuneable bandgaps that cover a broad spectral range, we expect that quantum dot microspectrometers will be useful in applications where minimizing size, weight, cost and complexity of the spectrometer are critical.
Recovering functions defined on the unit sphere by integration on a special family of sub-spheres
Salman, Yehonatan
2016-05-01
The aim of this article is to derive a reconstruction formula for the recovery of C1 functions, defined on the unit sphere {{{S}}}^{n - 1} , given their integrals on a special family of n - 2 dimensional sub-spheres. For a fixed point overline{a} strictly inside {{{S}}}^{n - 1} , each sub-sphere in this special family is obtained by intersection of {{{S}}}^{n - 1} with a hyperplane passing through overline{a} . The case overline{a} = 0 results in an inversion formula for the special case of integration on great spheres (i.e., Funk transform). The limiting case where pin {{{S}}}^{n - 1} and overline{a}→ p results in an inversion formula for the special case of integration on spheres passing through a common point in {{{S}}}^{n - 1}.
Objective Crystal Spectrometer on the SRG satellite
DEFF Research Database (Denmark)
Christensen, Finn Erland; Westergaard, Niels Jørgen Stenfeldt; Rasmussen, I.; Rasmussen, Ib Lundgaard; Schnopper, Herbert W.; Wiebicke, Hans-Joachim; Halm, Ingolf; Geppert, U.R.; Borozdin, K.N.
1994-01-01
The flight version of the Objective Crystal Spectrometer (OXS) on the SPECTRUM-X- GAMMA satellite is presented. The spectrometer is a panel that is placed in front of one of the SODART telescopes. It is composed of an array of the three Bragg crystals, LiF(220), Si(111) and RAP(001) for high...
High resolution magnetic spectrometer SHARAQ in RIBF
International Nuclear Information System (INIS)
For a new spectroscopy of nuclei using intense RI beams at RIBF, we started the SHARAQ project where a high-resolution SHARAQ spectrometer is being constructed together with a high-resolution secondary beam line. Physics motivation and the specification of the spectrometer are presented
Spin Spectrometer at the ALS and APS
Tobin, James G; Lawrence Livermore National Laboratory; University of Missouri-Rolla; Boyd Technologies
2008-01-01
A spin-resolving photoelectron spectrometer, the "Spin Spectrometer," has been designed and built. It has been utilized at both the Advanced Light Source in Berkeley, CA, and the Advanced Photon Source in Argonne, IL. Technical details and an example of experimental results are presented here.
A compact lightweight aerosol spectrometer probe (CLASP)
Hill, M.K.; Brooks, B.J.; Norris, S.J.; Smith, M.H.; Brooks, I.M.; Leeuw, G. de
2008-01-01
The Compact Lightweight Aerosol Spectrometer Probe (CLASP) is an optical particle spectrometer capable of measuring size-resolved particle concentrations in 16 user-defined size bins spanning diameters in the range 0.24 < D < 18.5 μm at a rate of 10 Hz. The combination of its compact nature and ligh
Laboratory EXAFS Spectrometer, Principles and Applications
Koningsberger, D.C.; Kampers, F.W.H.; Duivenvoorden, F.B.M.; Zon, J.B.A.D. van; Brinkgreve, P.; Viegers, M.P.A.
1985-01-01
In order to be independent of poor availability of synchrotron beamtime a laboratory EXAFS spectrometer has been developed. The X-ray source is a rotating anode generator (max. voltage 60 kV, max. current 300 mA). Monochromatisation and focusing is done with a linear spectrometer, based upon the Row
Introductory lecture on triple-axis spectrometer
International Nuclear Information System (INIS)
Triple-axis spectrometer is a multi-purpose instrument for powder neutron diffraction, single crystal neutron diffraction, powder inelastic neutron scattering, single crystal inelastic neutron scattering, and neutron polarization analysis. In this lecture how to use the triple-axis spectrometer is explained for the beginners. (author)
Artificial neural networks technology for neutron spectrometry and dosimetry
International Nuclear Information System (INIS)
Artificial Neural Network Technology has been applied to unfold neutron spectra and to calculate 13 dosimetric quantities using seven count rates from a Bonner Sphere Spectrometer with a 6LiI(Eu). Two different networks, one for spectrometry and another for dosimetry, were designed. To train and test both networks, 177 neutron spectra from the IAEA compilation were utilised. Spectra were re-binned into 31 energy groups, and the dosimetric quantities were calculated using the MCNP code and the fluence-to-dose conversion coefficients from ICRP 74. Neutron spectra and UTA4 response matrix were used to calculate the expected count rates in the Bonner spectrometer. Spectra and H*(10) of 239PuBe and 241AmBe were experimentally obtained and compared with those determined with the artificial neural networks. (authors)
Detector and spectrometer development for QED tests
International Nuclear Information System (INIS)
Full text: The curved crystal spectrometer will be implemented, calibrated and analyzed for further work to be carried out upon it at NIST in Washington for accurate precision tests of QED in highly charged ions. At the moment using the fluorescent source we are able to resolve characteristic x-ray lines for inner shell transitions Ka1, Ka2, and Kβ1,3 for differing elements. The curved crystal spectrometer has a Germanium crystal operating along the principle of Bragg's law. Using this spectrometer a second stage will be combining the backgammon detector with the curved crystal spectrometer and therefore experimental and theoretical work on curved crystal dynamical diffraction for the state of the art spectrometer will also be achieved
Integrated marketing communications in educational sphere
Baranova, A. S.; Баранова, А. С.
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....
Measurement of Neutron Transmission Through Iron Spheres
International Nuclear Information System (INIS)
We have measured the transmission of neutrons through iron spheres with several different neutron sources. The D(d,n) reaction and the 15N(n,p) reaction were found to be the best candidates for nearly monoenergetic sources at energies below 11 MeV. We have used a quasi monoenergetic source with 3.0-, 5.0-, and 7.0-MeV deuterons incident on a deuteron gas cell and 5.1-MeV protons incident on a 15N gas cell. The Ohio University Beam Swinger Facility was used in these measurements. This allowed a single fixed detector in a well-shielded time-of-flight (TOF) tunnel to be used for measurements at all angles. This allows a great reduction in the background from room scattered neutrons. The detector, either NE-213 or lithium glass, was calibrated relative to the neutron spectrum from the B(d,n) or the Al(d,n) source reaction. These spectra have been measured relative to the primary neutron standard, 235U(n, f). The transmitted neutrons have been measured for all source reactions at several angles. The data will be reported as the number of neutrons versus time-of-flight since multiple scattering does not allow the energy to be determined accurately by time-of-flight. We have also measured the source reaction at several angles to enhance the modeling of the source spectrum
Electrophoretic mobility of electrostatically interacting colloidal spheres
International Nuclear Information System (INIS)
We have measured the electrophoretic mobility μ = vE/E (where E is the electric field strength and vE the electrophoretic velocity) of highly charged colloidal spheres in deionized aqueous suspension at particle number densities n between 0.15 and 150 μm-3. Under these conditions the system exhibits fluid or crystalline order. We used laser Doppler velocimetry to determine the electrophoretic velocities vE as spatially averaged particle velocities from both integral and spatially resolved measurements. With this approach we were for the first time able to extend measurements far into the crystalline region of the phase diagram. We found μ to be constant at low n while at large n we observe an approximately logarithmic decrease in n. However, the descent of μ is not affected by the phase transition. This indicates that this transport coefficient rather depends on the local structure of the ionic clouds surrounding the particles than on the long range order of the suspension
Bubble entrapment during sphere impact onto quiescent liquid surfaces
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.
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.
Extrinsic Calibration of Camera Networks Using a Sphere
Directory of Open Access Journals (Sweden)
Junzhi Guan
2015-08-01
Full Text Available In this paper, we propose a novel extrinsic calibration method for camera networks using a sphere as the calibration object. First of all, we propose an easy and accurate method to estimate the 3D positions of the sphere center w.r.t. the local camera coordinate system. Then, we propose to use orthogonal procrustes analysis to pairwise estimate the initial camera relative extrinsic parameters based on the aforementioned estimation of 3D positions. Finally, an optimization routine is applied to jointly refine the extrinsic parameters for all cameras. Compared to existing sphere-based 3D position estimators which need to trace and analyse the outline of the sphere projection in the image, the proposed method requires only very simple image processing: estimating the area and the center of mass of the sphere projection. Our results demonstrate that we can get a more accurate estimate of the extrinsic parameters compared to other sphere-based methods. While existing state-of-the-art calibration methods use point like features and epipolar geometry, the proposed method uses the sphere-based 3D position estimate. This results in simpler computations and a more flexible and accurate calibration method. Experimental results show that the proposed approach is accurate, robust, flexible and easy to use.
Forming MOFs into spheres by use of molecular gastronomy methods.
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. PMID:24964774
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.
Synthesis and characterization of oil-chitosan composite spheres.
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
2013-01-01
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. PMID:23681059
Compression cracking of plastic spheres: a high speed photography study
International Nuclear Information System (INIS)
Failure of brittle spheres under compressive loading, both quasi static and dynamic, is a technologically important problem. However, so far, neither the stress state in a loaded nor the failure process in understood clearly. In fact, because the process of the failure of a loaded sphere is very rapid, it has not been possible to follow it when making static observations. We have, therefore, carried out a high-speed photographic study using framing rates of up to 200,000 frames per second to follow the sequence of events when polished 12.7 mm diameter spheres of acrylic resin are fragmented using a low-velocity impact apparatus. The latter consist of a 5.7 kg hammer, which is allowed to drop on to the test sphere from a height of 1.3 m and the entire event of impact and ensuing fracture is photographed with a rotating mirror camera (C-4). Form numerous impact experiments it has been found that as the impact load increases gradually, plastic flow and flattering of the sphere occurs at the contact region. The size of the flattened region continuous to grow with increasing impact load and when this region becomes sufficiently large, usually one or two cracks initiate at the periphery of the contact rather than in the bulk of the sphere. The surface cracks then grow into the bulk of the sphere at velocities in the range of 600-800 m s/sup -1/. It is interesting to note these crack velocities are the maximum observed velocities in this material, but these are only approx. 0.8 of the Rayleigh wave velocity, which is the theoretically predicted maximum crack velocity in brittle materials. It is argued that in order to cause the catastrophic failure of a solid sphere, it is necessary to cause plasticity in it which then leads to the generation of tensile hoop stresses at the circle of contact between the sphere and platen. (author)
International Nuclear Information System (INIS)
Highlights: • This paper is to study the heat transfer coefficient on spheres in a 3-D array. • Transient liquid crystal technique is used to measure temperature distributions. • A 3-D transient CFD model with different turbulence models is also developed. • v2‾-f Turbulence model is shown to be more suitable for simulating pebble arrangement. • Beneficial effect of Rein on heat transfer for pebbles is shown in test and model. - Abstract: With advantage of higher heat transfer area per unit mass, a pebble bed is usually adopted as an essential component for design of energy production systems and thermal energy storage (TES) systems. The majority of this paper investigates the sphere blockage ratio (β) on the thermal–hydraulic characteristics of a pebble with 14 spheres using a three-dimensional (3-D) computational fluid dynamics (CFD) model with the v2‾-f turbulence model. In a previous work, this model has been validated against measured distributions of the heat transfer coefficient on the selected spheres. The measured data are obtained using the transient liquid–crystal technique. According to the simulation results, the thermal–hydraulic characteristics in the sphere array can be captured reasonably with the present CFD model, including flow stagnation, flow separation, vortex formation and anisotropic characteristics of the heat transfer on the sphere surface. Comparisons of the simulation results for the sphere arrays with different blockage ratios show that the flow and turbulent intensity distributions are similar in most regions of a sphere array, except the portions between the pebbles. The heat transfer coefficient for the upstream spheres increases slightly as the blockage ratio decreases. However, a lower heat transfer coefficient is predicted for the downstream sphere if β is less than 0.75. In addition, the heat transfer coefficient around the front of a downstream sphere would not be influenced by the upstream spheres until
Miniature Ion-Mobility Spectrometer
Hartley, Frank T.
2006-01-01
The figure depicts a proposed miniature ion-mobility spectrometer that would be fabricated by micromachining. Unlike prior ion-mobility spectrometers, the proposed instrument would not be based on a time-of-flight principle and, consequently, would not have some of the disadvantageous characteristics of prior time-of-flight ion-mobility spectrometers. For example, one of these characteristics is the need for a bulky carrier-gas-feeding subsystem that includes a shutter gate to provide short pulses of gas in order to generate short pulses of ions. For another example, there is need for a complex device to generate pulses of ions from the pulses of gas and the device is capable of ionizing only a fraction of the incoming gas molecules; these characteristics preclude miniaturization. In contrast, the proposed instrument would not require a carrier-gas-feeding subsystem and would include a simple, highly compact device that would ionize all the molecules passing through it. The ionization device in the proposed instrument would be a 0.1-micron-thick dielectric membrane with metal electrodes on both sides. Small conical holes would be micromachined through the membrane and electrodes. An electric potential of the order of a volt applied between the membrane electrodes would give rise to an electric field of the order of several megavolts per meter in the submicron gap between the electrodes. An electric field of this magnitude would be sufficient to ionize all the molecules that enter the holes. Ionization (but not avalanche arcing) would occur because the distance between the ionizing electrodes would be less than the mean free path of gas molecules at the operating pressure of instrument. An accelerating grid would be located inside the instrument, downstream from the ionizing membrane. The electric potential applied to this grid would be negative relative to the potential on the inside electrode of the ionizing membrane and would be of a magnitude sufficient to
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
Dense packing of spheres around rods in supramolecular aggregates
International Nuclear Information System (INIS)
We consider a system of identically-sized spheres that coat a rod in a dense monolayer. We derive relationships that show how the number of spheres needed to cover a unit length of rod depends on the sphere and rod radii. The analysis could provide a stimulating exercise for students who have been introduced to the conventional examples of dense packing that are taught in many introductory physical science courses. The new class of liquid crystalline system which prompted this analysis may have applications in displays that can maintain stable liquid crystalline order over a broad range of temperatures. (author)
Simulations of a supersymmetry inspired model on a fuzzy sphere
International Nuclear Information System (INIS)
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.)
Simulations of a supersymmetry inspired model on a fuzzy sphere
Bietenholz, Wolfgang
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 variant of this model on a fuzzy sphere. The prospect to restore exact supersymmetry in certain limits is under investigation.
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.)
Echoes of the glass transition in athermal soft spheres
Morse, Peter; Corwin, Eric
The glass transition and the athermal jamming transition are both transitions from one disordered state to another marked by a sudden increase in rigidity. Before the onset of rigidity, thermal hard spheres and athermal soft spheres both share the same configuration space. Is there a signature of the glass transition in the topology of the allowed configuration space, and is this same signature present for athermal spheres? I will answer these questions by introducing the concept of local rigidity, and in doing so, I will demonstrate the existence of a pre-jamming phase transition precisely at the glass transition density.
VMware vSphere 4 Administration Instant Reference
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
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...
Superposition of nonlinear coherent states on a sphere
Directory of Open Access Journals (Sweden)
T Hosseinzadeh
2013-09-01
Full Text Available In this paper, by using the nonlinear coherent states on a sphere, we introduce superposition of the aforementioned coherent states. Then, we consider quantum optical properties of these new superposed states and compare these properties with the corresponding properties of the nonlinear coherent states on the sphere. Specifically, we investigate their characteristics function, photon-number distribution, Mandel parameter, quadrature squeezing, anti-bunching effect and Wigner function, and obtain the curvature effect on the properties of the superposed states. Finally, by using the trapped atom system, we introduce a theoretical scheme to generate superposition of the coherent states on the sphere.
High pressure gas spheres for neutron and photon experiments
Rupp, G.; Petrich, D.; Käppeler, F.; Kaltenbaek, J.; Leugers, B.; Reifarth, R.
2009-09-01
High pressure gas spheres have been designed and successfully used in several nuclear physics experiments on noble gases. The pros and cons of this solution are the simple design and the high reliability versus the fact that the density is limited to 40-60% of liquid or solid gas samples. Originally produced for neutron capture studies at keV energies, the comparably small mass of the gas spheres were an important advantage, which turned out to be of relevance for other applications as well. The construction, performance, and operation of the spheres are described and examples for their use are presented.
Uniqueness of photon spheres via positive mass rigidity
Cederbaum, Carla
2015-01-01
In a recent paper the first author established the uniqueness of photon spheres, suitably defined, in static vacuum asymptotically flat spacetimes by adapting Israel's proof of static black hole uniqueness. In this note we establish uniqueness of photon spheres by adapting the argument of Bunting and Masood-ul-Alam, which then allows certain assumptions to be relaxed. In particular, multiple photon spheres are allowed a priori. As a consequence of our result, we can rule out the existence of static configurations involving multiple "very compact" bodies and black holes.
Planetary method to measure the neutrons spectrum in lineal accelerators of medical use
International Nuclear Information System (INIS)
A novel procedure to measure the neutrons spectrum originated in a lineal accelerator of medical use has been developed. The method uses a passive spectrometer of Bonner spheres. The main advantage of the method is that only requires of a single shot of the accelerator. When this is used around a lineal accelerator is necessary to operate it under the same conditions so many times like the spheres that contain the spectrometer, activity that consumes enough time. The developed procedure consists on situating all the spheres of the spectrometer at the same time and to realize the reading making a single shot. With this method the photo neutrons spectrum produced by a lineal accelerator Varian ix of 15 MV to 100 cm of the isocenter was determined, with the spectrum is determined the total flow and the ambient dose equivalent. (Author)
Energy Technology Data Exchange (ETDEWEB)
Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Benites R, J. L., E-mail: fermineutron@yahoo.com [Centro Estatal de Cancerologia de Nayarit, Servicio de Seguridad Radiologica, Calzada de la Cruz 118 Sur, 63000 Tepic, Nayarit (Mexico)
2014-08-15
A novel procedure to measure the neutrons spectrum originated in a lineal accelerator of medical use has been developed. The method uses a passive spectrometer of Bonner spheres. The main advantage of the method is that only requires of a single shot of the accelerator. When this is used around a lineal accelerator is necessary to operate it under the same conditions so many times like the spheres that contain the spectrometer, activity that consumes enough time. The developed procedure consists on situating all the spheres of the spectrometer at the same time and to realize the reading making a single shot. With this method the photo neutrons spectrum produced by a lineal accelerator Varian ix of 15 MV to 100 cm of the isocenter was determined, with the spectrum is determined the total flow and the ambient dose equivalent. (Author)
Handheld spectrometers: the state of the art
Crocombe, Richard A.
2013-05-01
"Small" spectrometers fall into three broad classes: small versions of laboratory instruments, providing data, subsequently processed on a PC; dedicated analyzers, providing actionable information to an individual operator; and process analyzers, providing quantitative or semi-quantitative information to a process controller. The emphasis of this paper is on handheld dedicated analyzers. Many spectrometers have historically been large, possible fragile, expensive and complicated to use. The challenge over the last dozen years, as instruments have moved into the field, has been to make spectrometers smaller, affordable, rugged, easy-to-use, but most of all capable of delivering actionable results. Actionable results can dramatically improve the efficiency of a testing process and transform the way business is done. There are several keys to this handheld spectrometer revolution. Consumer electronics has given us powerful mobile platforms, compact batteries, clearly visible displays, new user interfaces, etc., while telecomm has revolutionized miniature optics, sources and detectors. While these technologies enable miniature spectrometers themselves, actionable information has demanded the development of rugged algorithms for material confirmation, unknown identification, mixture analysis and detection of suspicious materials in unknown matrices. These algorithms are far more sophisticated than the `correlation' or `dot-product' methods commonly used in benchtop instruments. Finally, continuing consumer electronics advances now enable many more technologies to be incorporated into handheld spectrometers, including Bluetooth, wireless, WiFi, GPS, cameras and bar code readers, and the continued size shrinkage of spectrometer `engines' leads to the prospect of dual technology or `hyphenated' handheld instruments.
International Nuclear Information System (INIS)
A programme of developing techniques for the construction and use of spark chambers in high-energy physics experiments has been undertaken. Several methods of construction have been tested and found satisfactory. One method is to cement aluminium plates to frames made from glass or Plexiglas strips. Another is to place the aluminium plates in grooves machined in Plexiglas, forming a ''shelf'' design. A chamber made of rows of wires was successfully operated with a He-alcohol mixture. These chambers can either be filled with gas and sealed, or gas can be passed through them continuously. Chambers have been constructed with plates of various thicknesses ranging from 0.032 in downwards. The operation of the chambers with various spacings between the plates was also investigated. The performance of these chambers, when filled with several different gases (Ne, He, A) and with gas-alcohol mixtures, has been investigated. Several methods of applying high-voltage pulses to the chambers have been attempted. The results of these investigations are presented. Spark chambers placed in a magnetic field can be used in principle to determine the momentum of charged particles and if lead converter-plates are incorporated with them, the resulting system should serve as a gamma-ray spectrometer of high resolution and high efficiency. A magnet with an 18-in useful diameter and a 13000-G field is being fitted with spark chambers, whose performance will be tested with cosmic rays and with an accelerator beam. Results from such tests are presented. (author)
Airborne fourier infrared spectrometer system
International Nuclear Information System (INIS)
A commercial Fourier Transform Infrared (FTIR) spectrometer has been interfaced to a 35 cm aperture telescope and a digital data processing and display system and flown in a downward-viewing configuration on a Queen Air aircraft. Real-time spectral analysis and display software were developed to provide the means to direct aircraft flight operations based on atmospheric and/or surface features identified on 1 to 8 cm-1 resolution infrared spectra. Data are presented from ground-based tests consisting of simultaneous horizontal path measurements by the FTIR system and an infrared differential absorption lidar (DIAL) observing gas volumes generated in an open-ended chamber. Airborne FUR data are presented on the tracking of a surface-released puff of SF6 gas to a downwind distance of 45 km in a time period of 1.5 hours. The experiment demonstrated the real time tracking of a gas tracer cloud to provide atmospheric transport and diffusion information and for directing airborne in-situ sensors for optimum cloud sampling. 5 refs., 5 figs
A semiconductor beta ray spectrometer
International Nuclear Information System (INIS)
Measurement of energy spectra of beta particles emitted from nuclei in beta-decay processes provides information concerning the mass difference of these nuclei between initial and final state. Moreover, experimental beta spectra yield information on the feeding of the levels in the daughter nucleus. Such data are valuable in the construction and checking of the level schemes. This thesis describes the design, construction, testing and usage of a detector for the accurate measurement of the mentioned spectra. In ch. 2 the design and construction of the beta spectrometer, which uses a hyper-pure germanium crystal for energy determination, is described. A simple wire chamber is used to discriminate beta particles from gamma radiation. Disadvantages arise from the large amounts of scattered beta particles deforming the continua. A method is described to minimize the scattering. In ch. 3 some theoretical aspects of data analysis are described and the results of Monte-Carlo simulations of the summation of annihilation radiation are compared with experiments. Ch. 4 comprises the results of the measurements of the beta decay energies of 103-108In. 87 refs.; 34 figs.; 7 tabs
Tidally Driven Dynamos in a Rotating Sphere
Cébron, D.; Hollerbach, R.
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 & 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.
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.
Energy Technology Data Exchange (ETDEWEB)
Gomez-Ros, J. M.; Romero, A.; Begogini, R.; Esposito, A.; Moraleda, M.; Lagares, J. I.; Sansaloni, F.; Arce, P.; Llop, J.
2011-07-01
In this communication, we present experimental results with a new neutron spectrometer, developed jointly by the Radiation Dosimetry Unit of CIEMAT Unita di Fisica and INFN-LNF Sanitary (Italy), consisting of a polyethylene moderating sphere detectors thermal neutrons (paired thermoluminescent dosimeters and activation foils) located in different positions. The device configuration and distribution of dosimeters are designed to elicit a response in a nearly isotropic up to 20 MeV energy range. (Author)
International Nuclear Information System (INIS)
The results of observations carried out with two scintillation spectrometers of ''Kosmos-914'' satellite used for searches for bursts of galactic hard X-rays are described. The comparison of the results obtained with ''Kosmos-428'' and ''Kosmos-856'' satellites is given. The results of observation of the Whale constellation and the celestial sphere area near the centre of Galaxy are given, where, according to the data of ''Kosmos-428'' satellite the presence of X-ray sources was experted
Calculation of bosonic matter fields on an N-sphere
International Nuclear Information System (INIS)
We solve the spectral problem and the Klein-Gordon equation for a massive and massless field theory on n-sphere, using a theory of hypergeometric equations developed by A. Nikiforov and V. Uvarov. (author)
Collapse of radiating fluid spheres and cosmic censorship
International Nuclear Information System (INIS)
The radiating-fluid-sphere model studied by Lake and Hellaby is reanalyzed to show that flat spacetime is a valid C1 extension to their model and thus it does not force a violation of strong cosmic censorship
Scattering from a multilayered chiral sphere using an iterative method
Shang, Qing-Chao; Wu, Zhen-Sen; Qu, Tan; Li, Zheng-Jun; Bai, Lu
2016-04-01
An iterative method for electromagnetic scattering from a multilayered chiral sphere is presented based on Lorenz-Mie regime. Electromagnetic fields in each region are expanded in terms of spherical vector wave functions. To calculate the scattering coefficients of the fields in outer space, an iterative form is constructed according to the coefficients equations obtained by the boundary condition on each layer. The iterative relations are expressed in forms of ratios and logarithmic derivatives of Riccati-Bessel functions, which can be calculated conveniently by their recurrence relations. The theory and codes are verified by comparing the scattered fields with those of a multilayered isotropic achiral sphere, and those of a single layered chiral sphere. Scattered fields of multilayered chiral spheres are presented and discussed, including a large sized case and a Gaussian beam incidence case.
[The power of religion in the public sphere] / Alar Kilp
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
Gender and Diversity in the European Public Spheres
DEFF Research Database (Denmark)
Siim, Birte
The increasing institutionalization of rights in EU has inspired a debate about the gap between the EU polity and citizens' abilities to influence multilevel governance and politics. The objective of the paper is to discuss diversity in the European public spheres from a gender perspective. It...... first gives an overview of different feminist approaches to diversity and intersectionality. It explores the arguments for and against creating a democratic European Public Sphere and discusses the tensions between universal principles of equality at the one hand and concerns for inequalities and...... state and to link feminist proposals for gender justice with frames for a multilayered trans-national citizenship. The paper aims to contribute to debates about theoretical approaches and models to study gender and diversity in the public sphere in general and in particular The European Public Sphere...
Transport properties of highly asymmetric hard-sphere mixtures.
Bannerman, Marcus N; Lue, Leo
2009-04-28
The static and dynamic properties of binary mixtures of hard spheres with a diameter ratio of sigma(B)/sigma(A)=0.1 and a mass ratio of m(B)/m(A)=0.001 are investigated using event driven molecular dynamics. The contact values of the pair correlation functions are found to compare favorably with recently proposed theoretical expressions. The transport coefficients of the mixture, determined from simulation, are compared to the predictions of the revised Enskog theory using both a third-order Sonine expansion and direct simulation Monte Carlo. Overall, the Enskog theory provides a fairly good description of the simulation data, with the exception of systems at the smallest mole fraction of larger spheres (x(A)=0.01) examined. A "fines effect" was observed at higher packing fractions, where adding smaller spheres to a system of large spheres decreases the viscosity of the mixture; this effect is not captured by the Enskog theory. PMID:19405594
Mechanism of drag reduction by dimples on a sphere
Choi, Jin; Jeon, Woo-Pyung; Choi, Haecheon
2006-04-01
In this Letter we present a detailed mechanism of drag reduction by dimples on a sphere such as golf-ball dimples by measuring the streamwise velocity above the dimpled surface. Dimples cause local flow separation and trigger the shear layer instability along the separating shear layer, resulting in the generation of large turbulence intensity. With this increased turbulence, the flow reattaches to the sphere surface with a high momentum near the wall and overcomes a strong adverse pressure gradient formed in the rear sphere surface. As a result, dimples delay the main separation and reduce drag significantly. The present study suggests that generation of a separation bubble, i.e., a closed-loop streamline consisting of separation and reattachment, on a body surface is an important flow-control strategy for drag reduction on a bluff body such as the sphere and cylinder.
Chemical flowsheet conditions for preparing urania spheres by internal gelation
International Nuclear Information System (INIS)
Small, ceramic urania spheres can be prepared for use as nuclear fuel by internal chemical gelation of uranyl nitrate solution droplets. Acid-deficient uranyl nitrate solutions up to 3.4 M in uranium with NO3-U mole ratios of 1.5 to 1.7 are prepared by dissolution of U3O8 or UO3. Decomposition of hexamethylenetetramine dissolved in the uranyl nitrate solution releases ammonia to precipitate hydrated UO/sub 3/. Previously established flowsheet conditions have been improved and modified at ORNL and have been applied to prepare dense UO2 spheres with average diameters of 1200, 300, and 30 μm. The 1200- and 300-μm UO2 spheres were prepared by gelation in trichloroethylene at 50 to 650C; 2-ethyl-1-hexanol was used as the gelation medium to prepare 30-μm UO2 spheres. 8 refs
Electromagnetic scattering by a partially charged multilayered sphere
International Nuclear Information System (INIS)
A new calculation procedure for the attenuation coefficients of electromagnetic wave by a partially charged multilayered sphere is proposed. The procedure is based on the utilization of a prescription which relates the expansion coefficients of the electromagnetic fields in the n-layered zone to those for the core zone through an iterative process, and then directly applies the coated-sphere model to calculate the expansion coefficients of the scattering field, and the extinction cross section. This method can be used to calculate the scattering properties of any multilayer charged sphere. - Highlights: • The scattering of electromagnetic (EM) wave by a charged multilayered sphere is discussed. • A new calculation procedure for the attenuation coefficient is proposed. • A semi-analytical expression for the attenuation coefficient is shown
Jets generated by a sphere moving vertically in stratified fluids
Hanazaki, Hideshi; Okino, Shinya; Nakamura, Shota; Akiyama, Shinsaku
2013-11-01
Unsteady development of buoyant jets generated by a sphere moving vertically at constant speeds in stratified fluids is investigated. Initially, the sphere simply drags light upper fluids or isopycnal surfaces as it goes down, as long as the molecular diffusion of density is negligible. In the succeeding period, molecular diffusion of density in the boundary layer on the sphere surface becomes increasingly significant, especially in the lower hemisphere. Then, the density is no longer conserved and a vertical jet starts from the rear/upper stagnation point of the sphere, since the fluid particle of altered but small density tends to go back to its original height. Strength and radius of those jets depend significantly on stratification (Froude number), as well as the Reynolds number and the Schmidt number. These mechanisms are investigated by numerical simulations and measurements by laser induced fluorescence (LIF).
A Reaction Sphere for High Performance Attitude Control Project
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...
Prototype sphere-on-sphere silica particles for the separation of large biomolecules.
Fekete, Szabolcs; Rodriguez-Aller, Marta; Cusumano, Alessandra; Hayes, Richard; Zhang, Haifei; Edge, Tony; Veuthey, Jean-Luc; Guillarme, Davy
2016-01-29
The goal of this study was to evaluate the possibilities offered by a prototype HPLC column packed with ∼2.5μm narrow size distribution sphere-on-sphere (SOS) silica particles bonded with C4 alkyl chains, for the analytical characterization of large biomolecules. The kinetic performance of this material was evaluated in both isocratic and gradient modes using various model analytes. The data were compared to those obtained on other widepore state-of-the-art fully core-shell and fully porous materials commonly employed to separate proteins moreover to a reference 5μm wide pore material that is still often used in QC labs. In isocratic mode, minimum reduced plate height values of hmin=2.6, 3.3 and 3.3 were observed on butylparaben, decapeptide and glucagon, respectively. In gradient elution mode, the SOS column performs very high efficiency when working with fast gradients. This prototype column was also comparable (and sometimes superior) to other widepore stationary phases, whatever the gradient time and flow rate, when analyzing the largest model protein, namely BSA. These benefits may be attributed to the SOS particle morphology, minimizing the intra-particle mass transfer resistance. Finally, the SOS column was also applied for the analytical characterization of commercial monoclonal antibody (mAb) and antibody-drug conjugate (ADC) samples. With these classes of proteins, the performance of SOS column was similar to the best widepore stationary phases available on the market. PMID:26755414
The high sensitivity double beta spectrometer TGV
Briancon, Ch.; Brudanin, V. B.; Egorov, V. G.; Janout, Z.; Koníček, J.; Kovalík, A.; Kovalenko, V. E.; Kubašta, J.; Pospíšil, S.; Revenko, A. V.; Rukhadze, N. I.; Salamatin, A. V.; Sandukovsky, V. G.; Štekl, I.; Timkin, V. V.; Tsupko-Sitnikov, V. V.; Vorobel, V.; Vylov, Ts.
1996-02-01
A high sensitivity double beta spectrometer TGV (Telescope Germanium Vertical) has been developed. It is based on 16 HPGe detectors of volume 1200 × 6 mm 3 each in the same cryostat. The TGV spectrometer was proposed for the study of ultrarare nuclear processes (e.g. 2νββ, 0νββ, 2νEC/EC). Details of the TGV spectrometer construction are described, the principles of background suppression, the results of Monte Carlo simulations and the results of test background measurements (in Dubna and Modane underground laboratory) are provided.
The high sensitivity double beta spectrometer TGV
International Nuclear Information System (INIS)
A high sensitivity double beta spectrometer TGV (Telescope Germanium Vertical) has been developed. It is based on 16 HPGe detectors of volume 1200 x 6 mm3 each in the same cryostat. The TGV spectrometer was proposed for the study of ultrarare nuclear processes (e.g. 2νββ, 0νββ, 2νEC/EC). Details of the TGV spectrometer construction are described, the principles of background suppression, the results of Monte Carlo simulations and the results of test background measurements (in Dubna and Modane underground laboratory) are provided. (orig.)
Mini-Orange Spectrometer at CIAE
Zheng, Yun; Li, Guang-Sheng; Li, Cong-Bo; He, Chuang-Ye; Chen, Qi-Ming; Zhong, Jian; Zhou, Wen-Kui; Deng, Li-Tao; Zhu, Bao-Ji
2016-01-01
A Mini-Orange spectrometer used for in-beam measurements of internal conversion electrons, which consists of a Si(Li) detector and different sets of SmO$_5$ permanent magnets for filtering and transporting the conversion electrons to the Si(Li) detector, has been developed at China Institute of Atomic Energy. The working principle and configuration of the Mini-Orange spectrometer are described. The performance of the setup is illustrated by measured singles conversion electron spectra using the Mini-Orange spectrometer.
Mini-orange spectrometer at CIAE
Zheng, Yun; Wu, Xiao-Guang; Li, Guang-Sheng; Li, Cong-Bo; He, Chuang-Ye; Chen, Qi-Ming; Zhong, Jian; Zhou, Wen-Kui; Deng, Li-Tao; Zhu, Bao-Ji
2016-08-01
A mini-orange spectrometer used for in-beam measurements of internal conversion electrons, consisting of a Si(Li) detector and different sets of SmO5 permanent magnets for filtering and transporting the conversion electrons to the Si(Li) detector, has been developed at the China Institute of Atomic Energy. The working principles and configuration of the mini-orange spectrometer are described. The performance of the setup is illustrated by measured singles conversion electron spectra using the mini-orange spectrometer. Supported by National Natural Science Foundation of China (11305269, 11375267, 11475072, 11405274, 11205068, 11175259)
Complex Response Function of Magnetic Resonance Spectrometers
Annino, G; Fittipaldi, M; Martinelli, M
2002-01-01
A vectorial analysis of magnetic resonance spectrometers, based on traveling wave resonators and including the reference arm and the automatic control of frequency, has been developed. The proposed modelization, valid also for stationary wave resonators, gives the response function of the spectrometer for any working condition, including scalar detectors with arbitrary responsivity law and arbitrary excitation frequency. The purely dispersive and purely absorptive linear responses are discussed in detail for different scalar detectors. The developed approach allows to optimize the performances of the spectrometer and to obtain the intrinsic lineshape of the sample in a very broad range of working conditions. More complex setups can be modelized following the proposed scheme.
Computer-controlled neutron spectrometer SV 22
International Nuclear Information System (INIS)
The neutron spectrometer SV22 is a combined time of flight and back scattering spectrometer. It is located at the tangential beam tube TAN2 of the research reactor FRJ2 DIDO at Kernforschungsanlage Juelich (West-Germany). Both versions are described in their hardware layout. The neutron optical characteristics of the already functioning time of flight spectrometer are summarized. Selected experiments show some possible fields for further research with this instrument. Experimental data for the backscattering version is not yet available. The features of the operating system RSX11M are explained. Examples show the use of indirect command files in control of the experiment. (orig.)
PAC Spectrometer for Condensed Matter Study
Kochetov, O I; Tsvyashchenko, A V; Akselrod, Z Z; Antuhov, V A; Busa, J; Velichkov, A I; Korolev, N A; Milanov, M V; Novgorodov, A F; Ostrovskii, I V; Pavlov, V N; Skrivanek, J; Timkin, V V; Filossofov, D V; Fomicheva, L N; Shirani, E N; Stekl, I; Brudanin, V B
2002-01-01
A four-detector perturbed angular \\gamma\\gamma-correlations (PAC) spectrometer for condensed matter study is described. The timing resolution (full-width at half-maximum) is 200 ps for ^{60}Co if BaF_2 scintillators coupled to photomultiplier XP2020Q are used. The spectrometer is equipped with a press; a specially-designed pressure vessel permits one to perform PAC-studies of samples under pressure up to 60 GPa in the on-line mode. In contrast to the common case (usage of single-channel analyzers) the software-controlled energy selection makes the spectrometer easy to use, to control and to adjust.
An affine sphere equation associated to Einstein toric surfaces
Mabuchi, Toshiki
2007-01-01
As seen in the works of Calabi, Cheng-Yau and Loftin, affine sphere equations have a close relationship with Kaehler-Einstein metrics. The main purpose of this note is to show that an equation analogous to those of hyperbolic affine spheres arises naturally from Kaehler-Einstein metrics on Einstein toric surfaces. The case for the remaining toric surfaces with Kaehler-Ricci solitons will also be discussed.
Strictly and non-strictly positive definite functions on spheres
Gneiting, Tilmann
2011-01-01
Isotropic positive definite functions on spheres play important roles in spatial statistics, where they occur as the correlation functions of homogeneous random fields and star-shaped random particles. In approximation theory, strictly positive definite functions serve as radial basis functions for interpolating scattered data on spherical domains. We review characterizations of positive definite functions on spheres in terms of Gegenbauer expansions and apply them to dimension walks, where m...
Extrinsic Calibration of Camera Networks Using a Sphere
Junzhi Guan; Francis Deboeverie; Maarten Slembrouck; Dirk Van Haerenborgh; Dimitri van Cauwelaert; Peter Veelaert; Wilfried Philips
2015-01-01
In this paper, we propose a novel extrinsic calibration method for camera networks using a sphere as the calibration object. First of all, we propose an easy and accurate method to estimate the 3D positions of the sphere center w.r.t. the local camera coordinate system. Then, we propose to use orthogonal procrustes analysis to pairwise estimate the initial camera relative extrinsic parameters based on the aforementioned estimation of 3D positions. Finally, an optimization routine is applied t...
Public Sphere in Totalitarian Period. The Romanian Case
Luminiţa ROŞCA
2010-01-01
This paper proposes an analysis pattern of the existence forms of the public sphere in the totalitarian pe riod from Romania. The analysis took into consideration essential reference in shaping the notion of public sphere: public communication and mass communication, public authority and the public exercise of reason. The scope of the research is to offer scientific significance to an array of testimonies from that period, regarding the situation of the individual and the society in the late ...
Experimental Investigation of Mechanical Properties of Metallic Hollow Sphere Structures
Friedl, O.; Motz, C.; Peterlik, H.; Puchegger, S.; Reger, N.; Pippan, R.
2008-02-01
Metallic foam was fabricated from 316L stainless steel spheres, where the bonding of the spheres was achieved by a sintering process. The mechanical behavior of a low-density material (0.3 g/cm3) with 2- and 4-mm sphere diameter and a high-density material (0.6 g/cm3) with 4-mm sphere diameter was investigated in compression and tension. The cell wall material of this hollow sphere structure (HSS) had different morphologies: dense and porous sintered walls were investigated. The cell wall morphology affects the Young’s modulus (stiffness) and the ductility of the HSS material. Defects, such as the cell wall porosity, lower the ductility of the material. Besides the quasi-static measurements, the HSS material was tested with a resonance frequency method (dynamic measurement), to obtain detailed information on the stiffness at different temperatures up to 700 °C. In-situ compression and tension tests were carried out to understand the deformation mechanisms on the scale of the single hollow spheres. The failure mechanisms in the vicinity of the sintering neck of the spheres was investigated. A doubling of the density leads to an increase of the plateau stress and the ultimate tensile stress of the material, whereas the ductility (strain to fracture) depended mainly on the cell wall morphology. Due to the mainly tensile loading of the cell walls in the vicinity of the sinter neck, the ultimate tensile strength doubled for the high-density HSS, in good agreement with theoretical considerations. In compression, the gain in the plateau stress was not as distinctive compared with the theoretical considerations assuming a bending dominated deformation. The influence of structural parameters, such as cell wall morphology, cell wall thickness, and sphere diameter, on the mechanical behavior is discussed.
Spheres of isolation: adaptation of isolation levels to transactional workflow
Guabtni, Adnene; Charoy, François; Godart, Claude
2005-01-01
In Workflow Management Systems (WFMSs), transaction isolation is managed most of the time by the underlying database system using ANSI SQL strategies. These strategies do not take sufficiently into account process aspects. Our work consists in studying with more depth the relation between isolation strategy and process dimension as well as the real isolation needs in workflow environments. To carry out these needs, we define `spheres of isolation' inspired from `spheres of control' proposed b...
Hard Sphere Dynamics for Normal and Granular Fluids
Dufty, James W.; Baskaran, Aparna
2005-01-01
A fluid of N smooth, hard spheres is considered as a model for normal (elastic collisions) and granular (inelastic collisions) fluids. The potential energy is discontinuous for hard spheres so the pairwise forces are singular and the usual forms of Newtonian and Hamiltonian mechanics do not apply. Nevertheless, particle trajectories in the N particle phase space are well defined and the generators for these trajectories can be identified. The first part of this presentation is a review of the...
Hydrodynamic limit Of a binary mixture Of rigid spheres
CHOE, HI JUN; Zhou, Shulin
2015-01-01
In this paper, we study the hydrodynamic limit of a binary mixture of rigid spheres. When Knudsen numbers of two different species are equal and go to zero, we show formally that the hydrodynamic variables satisfy the compressible Euler and Navier-Stokes equations. Like single species gas, we develop Enskog-Chapman theory up to the second order. It turns out that the macro velocities corresponding to the different spheres are equal and the ratio of the temperatures is the...
The Jerry Springer Show as an Emotional Public Sphere
Lunt, P.; Stenner, P.
2005-01-01
The public sphere debate in social theory has been a topic of considerable interest amongst scholars analysing the talk show genre. Habermas (1989) attached great importance to the potential of rational critical discussion to create consensus and thereby legitimation in democratic society. He was concerned that the media gave a false impression of engagement in a public sphere while managing rights of access and speech in a manner that was inimical to open public discussion. In contrast, cult...
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.
Generalized non-associative structures on the 7-sphere
da Rocha, Roldao; Traesel, M. A.
2011-01-01
In this paper we provide a more general class of non-associative products using the exterior and Clifford bundles on the 7-sphere. Some additional properties encompass previous formalisms in the Clifford algebra context, and wider classes of non-associative structures on the 7-sphere are investigated, evinced by the directional non-associative products and the mixed composition of generalized non-associative products between Clifford algebra multivectors. These non-associative products are fu...
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.
Formal Variability of Terms in the Sphere of Network Technologies
Roman Viktorovich Deniko; Olga Grigoryevna Shchitova
2015-01-01
The article addresses the problem of formal variability of terms in the sphere of network terminology in the Russian language. The research is based on data from the Internet communication in the sphere of network technologies. Such formal variability types as graphical, phonemic, word building and complex (graphic and phonetic, morphologic and accentual) are discussed in this article. The authors reveal the reasons for graphic variability of foreign origin terms making up the international t...
Chemical flowsheet conditions for preparing urania spheres by internal gelation
International Nuclear Information System (INIS)
Small, ceramic urania spheres can be prepared for use as nuclear fuel by internal chemical gelation of uranyl nitrate solution droplets. Decomposition of hexamethylenetetramine (HMTA) dissolved in the uranyl nitrate solution releases ammonia to precipitate hydrated UO3. Previously established flowsheet conditions have been improved and modified at ORNL and have been applied to prepare dense UO2 spheres with average diameters of 1200, 300, and 30 μm
Relaxation of Thick-Walled Cylinders and Spheres
DEFF Research Database (Denmark)
Saabye Ottosen, N.
1982-01-01
Using the nonlinear creep law proposed by Soderberg, (1936) closed-form solutions are derived for the relaxation of incompressible thick-walled spheres and cylinders in plane strain. These solutions involve series expressions which, however, converge very quickly. By simply ignoring these series...... expressions, extremely simple approximate solutions are obtained. Despite their simplicity these approximations possess an accuracy that is superior to approximations currently in use. Finally, several physical aspects related to the relaxation of cylinders and spheres are discussed...
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.
Global Calibration of Multiple Cameras Based on Sphere Targets.
Sun, Junhua; He, Huabin; Zeng, Debing
2016-01-01
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. PMID:26761007
Ellipsoids beat Spheres: Experiments with Candies, Colloids and Crystals
Chaikin, Paul
2006-04-01
How many gumballs fit in the glass sphere of a gumball machine? Scientists have been puzzling over problems like this since the Ancient Greeks. Yet it was only recently proven that the standard way of stacking oranges at a grocery store--with one orange on top of each set of three below--is the densist packing for spheres, with a packing fraction φ˜ 0.74. Random (amorphous) packings of spheres have a lower density, with φ ˜0.64. The density of crystalline and random packings of atoms is intimately related to the melting transition in matter. We have studied the crystal-liquid transition in spherical colloidal systems on earth and in microgravity. The simplest objects to study after spheres are squashed spheres -- ellipsoids. Surprisingly we find that ellipsoids can randomly pack more densely than spheres, up to φ˜0.68 - 0.71 for a shape close to that of M&M's^ Candies, and even approach φ˜0.75 for general ellipsoids. The higher density relates directly to the higher number of neighbors needed to prevent the more asymetric ellipsoid from rotating. We have also found the ellipsoids can be packed in a crystalline array to a density, φ˜.7707 which exceeds the highest previous packing. Our findings provide insights into granular materials, rigidity, crystals and glasses, and they may lead to higher quality ceramic materials.
Multiple scattering of a spherical acoustic wave from fluid spheres
Wu, J. H.; Liu, A. Q.; Chen, H. L.; Chen, T. N.
2006-02-01
The multiple scattering of a spherical acoustic wave from an arbitrary number of fluid spheres is investigated theoretically. The tool to attack the multiple scattering problem is a kind of addition formulas for the spherical wave functions, which are presented in the paper, based on the bicentric expansion form of Green function in the spherical coordinates. For an arbitrary configuration of N fluid spheres, the kind of addition formulas permits the field expansions (all referred to the center of each sphere). With these the sound fields scattered by each sphere can be described by a set of N equations. The interactions between any two fluid spheres are taken into account in these equations exactly and their coefficients are coupled through double sums in the spherical wave functions. By truncating the infinite series in the equations depending on certain calculation accuracy and solving the coefficients matrix by using the Gauss-Seidel iteration method, we can obtain the scattered sound field by the configuration of the fluid spheres. Finally, the scattering calculations by using the kind of addition formulas are carried out.
Global Calibration of Multiple Cameras Based on Sphere Targets
Sun, Junhua; He, Huabin; Zeng, Debing
2016-01-01
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. PMID:26761007
Squeeze flow of a Carreau fluid during sphere impact
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.
The VERDI fission fragment spectrometer
International Nuclear Information System (INIS)
The VERDI time-of-flight spectrometer is dedicated to measurements of fission product yields and of prompt neutron emission data. Pre-neutron fission-fragment masses will be determined by the double time-of-flight (TOF) technique. For this purpose an excellent time resolution is required. The time of flight of the fragments will be measured by electrostatic mirrors located near the target and the time signal coming from silicon detectors located at 50 cm on both sides of the target. This configuration, where the stop detector will provide us simultaneously with the kinetic energy of the fragment and timing information, significantly limits energy straggling in comparison to legacy experimental setup where a thin foil was usually used as a stop detector. In order to improve timing resolution, neutron transmutation doped silicon will be used. The high resistivity homogeneity of this material should significantly improve resolution in comparison to standard silicon detectors. Post-neutron fission fragment masses are obtained form the time-of-flight and the energy signal in the silicon detector. As an intermediary step a diamond detector will also be used as start detector located very close to the target. Previous tests have shown that poly-crystalline chemical vapour deposition (pCVD) diamonds provides a coincidence time resolution of 150 ps not allowing complete separation between very low-energy fission fragments, alpha particles and noise. New results from using artificial single-crystal diamonds (sCVD) show similar time resolution as from pCVD diamonds but also sufficiently good energy resolution. (authors)
The VERDI fission fragment spectrometer
Directory of Open Access Journals (Sweden)
Frégeau M.O.
2013-12-01
Full Text Available The VERDI time-of-flight spectrometer is dedicated to measurements of fission product yields and of prompt neutron emission data. Pre-neutron fission-fragment masses will be determined by the double time-of-flight (TOF technique. For this purpose an excellent time resolution is required. The time of flight of the fragments will be measured by electrostatic mirrors located near the target and the time signal coming from silicon detectors located at 50 cm on both sides of the target. This configuration, where the stop detector will provide us simultaneously with the kinetic energy of the fragment and timing information, significantly limits energy straggling in comparison to legacy experimental setup where a thin foil was usually used as a stop detector. In order to improve timing resolution, neutron transmutation doped silicon will be used. The high resistivity homogeneity of this material should significantly improve resolution in comparison to standard silicon detectors. Post-neutron fission fragment masses are obtained form the time-of-flight and the energy signal in the silicon detector. As an intermediary step a diamond detector will also be used as start detector located very close to the target. Previous tests have shown that poly-crystalline chemical vapour deposition (pCVD diamonds provides a coincidence time resolution of 150 ps not allowing complete separation between very low-energy fission fragments, alpha particles and noise. New results from using artificial single-crystal diamonds (sCVD show similar time resolution as from pCVD diamonds but also sufficiently good energy resolution.
Multidetector calibration for mass spectrometers
International Nuclear Information System (INIS)
The International Atomic Energy Agency's Safeguards Analytical Laboratory has performed calibration experiments to measure the different efficiencies among multi-Faraday detectors for a Finnigan-MAT 261 mass spectrometer. Two types of calibration experiments were performed: (1) peak-shift experiments and (2) peak-jump experiments. For peak-shift experiments, the ion intensities were measured for all isotopes of an element in different Faraday detectors. Repeated measurements were made by shifting the isotopes to various Faraday detectors. Two different peak-shifting schemes were used to measure plutonium (UK Pu5/92138) samples. For peak-jump experiments, ion intensities were measured in a reference Faraday detector for a single isotope and compared with those measured in the other Faraday detectors. Repeated measurements were made by switching back-and-forth between the reference Faraday detector and a selected Faraday detector. This switching procedure is repeated for all Faraday detectors. Peak-jump experiments were performed with replicate measurements of 239Pu, 187Re, and 238U. Detector efficiency factors were estimated for both peak-jump and peak-shift experiments using a flexible calibration model to statistically analyze both types of multidetector calibration experiments. Calculated detector efficiency factors were shown to depend on both the material analyzed and the experimental conditions. A single detector efficiency factor is not recommended for each detector that would be used to correct routine sample analyses. An alternative three-run peak-shift sample analysis should be considered. A statistical analysis of the data from this peak-shift experiment can adjust the isotopic ratio estimates for detector differences due to each sample analysis
Oliva, E.; Origlia, L.; Baffa, C.; Biliotti, C.; Bruno, P.; D'Amato, F.; Del Vecchio, C.; Falcini, G.; Gennari, S.; Ghinassi, F.; Giani, E.; Gonzalez, M.; Leone, F.; Lolli, M.; Lodi, M.; Maiolino, R.; Mannucci, F.; Marcucci, G.; Mochi, I.; Montegriffo, P.; Rossetti, E.; Scuderi, S.; Sozzi, M.
2006-06-01
GIANO is an infrared (0.9-2.5 μm cross-dispersed echelle spectrometer designed to achieve high resolution, high throughput, wide band coverage and very high stability for accurate radial velocity measurements. It also includes polarimetric capabilities and a low resolution mode with RS ~ 400 and complete 0.75-2.5 μm coverage. This makes it a very versatile, common user instrument which will be permanently mounted and available on the Nasmyth-B foci of the Telescopio Nazionale Galileo (TNG) located at Roque de Los Muchachos Observatory (ORM), La Palma, Spain. The project is fast-track and relies on well known, relatively standard technologies. It has been recognized as one of the top priority instrumental projects of INAF (the Italian National Institute of Astronomy) and received its first financing for the phase-A study in October 2003. Integration in the laboratory is planned to start before the end of 2006, commissioning at the telescope is foreseen within 2007 and scientific operations in 2008. One of the most important scientific goals is the search for rocky planets with habitable conditions around low-mass stars. If completed on time, GIANO will be the first and only IR instrument operating worldwide providing the combination of efficiency, spectral resolution, wavelength coverage and stability necessary for this type of research. With its unique combination of high and low resolution modes, GIANO will also be a very flexible common-user instrument ideal e.g. for quantitative spectroscopy of brown dwarfs, stars and stellar clusters as well as for the determination of the spectral energy distribution of faint/red objects such as high redshift galaxies. The expected limiting magnitudes are such that GIANO will be able to deliver good quality HR spectra of any 2MASS object and LR spectra of any object detected in the UKIDSS large area survey.
Portable Remote Imaging Spectrometer (PRISM) Project
National Aeronautics and Space Administration — Develop an UV-NIR (350nm to 1050 nm) portable remote imaging spectrometer (PRISM) for flight on a variety of airborne platforms with high SNR and response...
Calibration of a photomultiplier array spectrometer
Bailey, Steven A.; Wright, C. Wayne; Piazza, Charles R.
1989-01-01
A systematic approach to the calibration of a photomultiplier array spectrometer is presented. Through this approach, incident light radiance derivation is made by recognizing and tracing gain characteristics for each photomultiplier tube.
Remote UV Fluorescence Lifetime Spectrometer Project
National Aeronautics and Space Administration — The goal of this project is to develop, demonstrate, and deliver to NASA an innovative, portable, and power efficient Remote UV Fluorescence Lifetime Spectrometer...
Low Power Mass Spectrometer employing TOF Project
National Aeronautics and Space Administration — A low power Mass Spectrometer employing multiple time of flight circuits for parallel processing is possible with a new innovation in design of the Time of flight...
View of the Axial Field Spectrometer
1980-01-01
The Axial Field Spectrometer, with the vertical uranium/scintillator calorimeter and the central drift chamber retracted for service. One coil of the Open Axial Field Magnet is just visible to the right.
Low Power FPGA Based Spectrometer Project
National Aeronautics and Space Administration — We propose to design a general purpose reconfigurable wide bandwidth spectrometer for use in NASA's passive microwave missions, deep space network and radio...