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Sample records for nuclei clumpy torus

BayesCLUMPY: BAYESIAN INFERENCE WITH CLUMPY DUSTY TORUS MODELS

International Nuclear Information System (INIS)

Asensio Ramos, A.; Ramos Almeida, C.

2009-01-01

Our aim is to present a fast and general Bayesian inference framework based on the synergy between machine learning techniques and standard sampling methods and apply it to infer the physical properties of clumpy dusty torus using infrared photometric high spatial resolution observations of active galactic nuclei. We make use of the Metropolis-Hastings Markov Chain Monte Carlo algorithm for sampling the posterior distribution function. Such distribution results from combining all a priori knowledge about the parameters of the model and the information introduced by the observations. The main difficulty resides in the fact that the model used to explain the observations is computationally demanding and the sampling is very time consuming. For this reason, we apply a set of artificial neural networks that are used to approximate and interpolate a database of models. As a consequence, models not present in the original database can be computed ensuring continuity. We focus on the application of this solution scheme to the recently developed public database of clumpy dusty torus models. The machine learning scheme used in this paper allows us to generate any model from the database using only a factor of 10 -4 of the original size of the database and a factor of 10 -3 in computing time. The posterior distribution obtained for each model parameter allows us to investigate how the observations constrain the parameters and which ones remain partially or completely undetermined, providing statistically relevant confidence intervals. As an example, the application to the nuclear region of Centaurus A shows that the optical depth of the clouds, the total number of clouds, and the radial extent of the cloud distribution zone are well constrained using only six filters. The code is freely available from the authors.
NEAR-INFRARED REVERBERATION BY DUSTY CLUMPY TORI IN ACTIVE GALACTIC NUCLEI

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Kawaguchi, Toshihiro; Mori, Masao

2011-01-01

According to recent models, the accretion disk and black hole in active galactic nuclei (AGNs) are surrounded by a clumpy torus. We investigate the NIR flux variation of the torus in response to a UV flash for various geometries. Anisotropic illumination by the disk and the torus self-occultation contrast our study with earlier works. Both the waning effect of each clump and the torus self-occultation selectively reduce the emission from the region with a short delay. Therefore, the NIR delay depends on the viewing angle (where a more inclined angle leads to a longer delay), and the time response shows an asymmetric profile with negative skewness, opposing the results for optically thin tori. The range of the computed delay coincides with the observed one, suggesting that the viewing angle is primarily responsible for the scatter of the observed delay. We also propose that the red NIR-to-optical color of type 1.8/1.9 objects is caused not only by the dust extinction but also the intrinsically red color. Compared with the modest torus thickness, both a thick and a thin tori display weaker NIR emission. A selection bias is thus expected such that NIR-selected AGNs tend to possess moderately thick tori. A thicker torus shows a narrower and more heavily skewed time profile, while a thin torus produces a rapid response. A super-Eddington accretion rate leads to much weaker NIR emission due to the disk self-occultation and the disk truncation by self-gravity. A long delay is expected from an optically thin and/or a largely misaligned torus. Very weak NIR emission, such as in hot-dust-poor active nuclei, can arise from a geometrically thin torus, a super-Eddington accretion rate, or a slightly misaligned torus.
THE DIFFERENCES IN THE TORUS GEOMETRY BETWEEN HIDDEN AND NON-HIDDEN BROAD LINE ACTIVE GALACTIC NUCLEI

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Ichikawa, Kohei; Ueda, Yoshihiro [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Packham, Christopher; Lopez-Rodriguez, Enrique; Alsip, Crystal D. [Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 (United States); Almeida, Cristina Ramos; Ramos, Andrés Asensio; González-Martín, Omaira [Instituto de Astrofísica de Canarias, C/Vía Láctea, s/n, E-38205 La Laguna, Tenerife (Spain); Alonso-Herrero, Almudena [Instituto de Física de Cantabria, CSIC-Universidad de Cantabria, E-39005 Santander (Spain); Díaz-Santos, Tanio [Spitzer Science Center, California Institute of Technology, MS 220-6, Pasadena, CA 91125 (United States); Elitzur, Moshe [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055 (United States); Hönig, Sebastian F. [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Imanishi, Masatoshi [Subaru Telescope, 650 North A’ohoku Place, Hilo, HI 96720 (United States); Levenson, Nancy A. [Gemini Observatory, Southern Operations Center, c/o AURA, Casilla 603, La Serena (Chile); Mason, Rachel E. [Gemini Observatory, Northern Operations Center, 670 N. A’ohoku Place, Hilo, HI 96720 (United States); Perlman, Eric S., E-mail: ichikawa@kusastro.kyoto-u.ac.jp [Department of Physics and Space Sciences, 150 W. University Blvd., Florida Institute of Technology, Melbourne, FL 32901 (United States)

2015-04-20

We present results from the fitting of infrared (IR) spectral energy distributions of 21 active galactic nuclei (AGNs) with clumpy torus models. We compiled high spatial resolution (∼0.3–0.7 arcsec) mid-IR (MIR) N-band spectroscopy, Q-band imaging, and nuclear near- and MIR photometry from the literature. Combining these nuclear near- and MIR observations, far-IR photometry, and clumpy torus models enables us to put constraints on the torus properties and geometry. We divide the sample into three types according to the broad line region (BLR) properties: type-1s, type-2s with scattered or hidden broad line region (HBLR) previously observed, and type-2s without any published HBLR signature (NHBLR). Comparing the torus model parameters gives us the first quantitative torus geometrical view for each subgroup. We find that NHBLR AGNs have smaller torus opening angles and larger covering factors than HBLR AGNs. This suggests that the chance to observe scattered (polarized) flux from the BLR in NHBLR could be reduced by the dual effects of (a) less scattering medium due to the reduced scattering volume given the small torus opening angle and (b) the increased torus obscuration between the observer and the scattering region. These effects give a reasonable explanation for the lack of observed HBLR in some type-2 AGNs.
First X-ray Statistical Tests for Clumpy-Torus Models: Constraints from RXTEmonitoring of Seyfert AGN

Science.gov (United States)

Markowitz, Alex; Krumpe, Mirko; Nikutta, R.

2016-06-01

In two papers (Markowitz, Krumpe, & Nikutta 2014, and Nikutta et al., in prep.), we derive the first X-ray statistical constraints for clumpy-torus models in Seyfert AGN by quantifying multi-timescale variability in line of-sight X-ray absorbing gas as a function of optical classification.We systematically search for discrete absorption events in the vast archive of RXTE monitoring of 55 nearby type Is and Compton-thin type IIs. We are sensitive to discrete absorption events due to clouds of full-covering, neutral/mildly ionized gas transiting the line of sight. Our results apply to both dusty and non-dusty clumpy media, and probe model parameter space complementary to that for eclipses observed with XMM-Newton, Suzaku, and Chandra.We detect twelve eclipse events in eight Seyferts, roughly tripling the number previously published from this archive. Event durations span hours to years. Most of our detected clouds are Compton-thin, and most clouds' distances from the black hole are inferred to be commensurate with the outer portions of the BLR or the inner regions of infrared-emitting dusty tori.We present the density profiles of the highest-quality eclipse events; the column density profile for an eclipsing cloud in NGC 3783 is doubly spiked, possibly indicating a cloud that is being tidallysheared. We discuss implications for cloud distributions in the context of clumpy-torus models. We calculate eclipse probabilities for orientation-dependent Type I/II unification schemes.We present constraints on cloud sizes, stability, and radial distribution. We infer that clouds' small angular sizes as seen from the SMBH imply 107 clouds required across the BLR + torus. Cloud size is roughly proportional to distance from the black hole, hinting at the formation processes (e.g., disk fragmentation). All observed clouds are sub-critical with respect to tidal disruption; self-gravity alone cannot contain them. External forces, such as magnetic fields or ambient pressure, are
AN OCCULTATION EVENT IN CENTAURUS A AND THE CLUMPY TORUS MODEL

International Nuclear Information System (INIS)

Rivers, Elizabeth; Markowitz, Alex; Rothschild, Richard

2011-01-01

We have analyzed 16 months of sustained monitoring observations of Centaurus A from the Rossi X-Ray Timing Explorer to search for changes in the absorbing column in the line of sight to the central nucleus. We present time-resolved spectroscopy which indicates that a discrete clump of material transited the line of sight to the central illuminating source over the course of ∼170 days between 2010 August and 2011 February with a maximum increase in the column density of about 8.4 × 10 22 cm –2 . This is the best quality data of such an event that has ever been analyzed with the shape of the ingress and egress clearly seen. Modeling the clump of material as roughly spherical with a linearly decreasing density profile and assuming a distance from the central nucleus commensurate with the dusty torus, we found that the clump would have a diameter of (1.4-2.4) × 10 15 cm with a central number density of n H = (1.8-3.0) × 10 7 cm –3 . This is consistent with previous results for a similar (though possibly much longer) occultation event inferred in this source in 2003-2004 and supports models of the molecular torus as a clumpy medium.
AN OCCULTATION EVENT IN CENTAURUS A AND THE CLUMPY TORUS MODEL

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Rivers, Elizabeth; Markowitz, Alex; Rothschild, Richard, E-mail: erivers@ucsd.edu [Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0424 (United States)

2011-12-15

We have analyzed 16 months of sustained monitoring observations of Centaurus A from the Rossi X-Ray Timing Explorer to search for changes in the absorbing column in the line of sight to the central nucleus. We present time-resolved spectroscopy which indicates that a discrete clump of material transited the line of sight to the central illuminating source over the course of {approx}170 days between 2010 August and 2011 February with a maximum increase in the column density of about 8.4 Multiplication-Sign 10{sup 22} cm{sup -2}. This is the best quality data of such an event that has ever been analyzed with the shape of the ingress and egress clearly seen. Modeling the clump of material as roughly spherical with a linearly decreasing density profile and assuming a distance from the central nucleus commensurate with the dusty torus, we found that the clump would have a diameter of (1.4-2.4) Multiplication-Sign 10{sup 15} cm with a central number density of n{sub H} = (1.8-3.0) Multiplication-Sign 10{sup 7} cm{sup -3}. This is consistent with previous results for a similar (though possibly much longer) occultation event inferred in this source in 2003-2004 and supports models of the molecular torus as a clumpy medium.
AN X-RAY SPECTRAL MODEL OF REPROCESSING BY SMOOTH AND CLUMPY MOLECULAR TORI IN ACTIVE GALACTIC NUCLEI WITH THE MONACO FRAMEWORK

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Furui, Shun’ya; Fukazawa, Yasushi; Ohno, Masanori; Hayashi, Kazuma [Department of Physical Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Odaka, Hirokazu [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 2575 Sand Hill Rd, Menlo Park, CA 94025 (United States); Kawaguchi, Toshihiro, E-mail: fukazawa@hep01.hepl.hiroshima-u.ac.jp [Department of Liberal Arts and Sciences, Sapporo Medical University, S1W17, Chuo-ku, Sapporo 060-8556 (Japan)

2016-02-20

We construct an X-ray spectral model of reprocessing by a torus in an active galactic nucleus (AGN) with the Monte Carlo simulation framework MONACO. Two torus geometries of smooth and clumpy cases are considered and compared. In order to reproduce a Compton shoulder accurately, MONACO includes not only free electron scattering but also bound electron scattering. Raman and Rayleigh scattering are also treated, and scattering cross sections dependent on chemical states of hydrogen and helium are included. Doppler broadening by turbulence velocity can be implemented. Our model gives results consistent with other available models, such as MYTorus, except for differences due to different physical parameters and assumptions. We studied the dependence on torus parameters for a Compton shoulder, and found that a intensity ratio of a Compton shoulder to the line core mainly depends on column density, inclination angle, and metal abundance. For instance, an increase of metal abundance makes a Compton shoulder relatively weak. Also, the shape of a Compton shoulder depends on the column density. Furthermore, these dependences become different between smooth and clumpy cases. Then, we discuss the possibility of ASTRO-H/SXS spectroscopy of Compton shoulders in AGN reflection spectra.
Clumpy cold dark matter

Science.gov (United States)

Silk, Joseph; Stebbins, Albert

1993-01-01

A study is conducted of cold dark matter (CDM) models in which clumpiness will inhere, using cosmic strings and textures suited to galaxy formation. CDM clumps of 10 million solar mass/cu pc density are generated at about z(eq) redshift, with a sizable fraction surviving. Observable implications encompass dark matter cores in globular clusters and in galactic nuclei. Results from terrestrial dark matter detection experiments may be affected by clumpiness in the Galactic halo.
No more active galactic nuclei in clumpy disks than in smooth galaxies at z ∼ 2 in CANDELS/3D-HST

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Trump, Jonathan R.; Luo, Bin; Brandt, W. N. [Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States); Barro, Guillermo; Guo, Yicheng; Koo, David C.; Faber, S. M. [University of California Observatories/Lick Observatory and Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Juneau, Stéphanie [Irfu/Service d' Astrophysique, CEA-Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette Cedex (France); Weiner, Benjamin J. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Brammer, Gabriel B.; Ferguson, Henry C.; Grogin, Norman A.; Kartaltepe, Jeyhan; Koekemoer, Anton M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bell, Eric F. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Dekel, Avishai [Center for Astrophysics and Planetary Science, Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel); Hopkins, Philip F. [California Institute of Technology, MC 105-24, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Kocevski, Dale D. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States); McIntosh, Daniel H. [Department of Physics and Astronomy, University of Missouri-Kansas City, 5110 Rockhill Road, Kansas City, MO 64110 (United States); Momcheva, Ivelina [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); and others

2014-10-01

We use CANDELS imaging, 3D-HST spectroscopy, and Chandra X-ray data to investigate if active galactic nuclei (AGNs) are preferentially fueled by violent disk instabilities funneling gas into galaxy centers at 1.3 < z < 2.4. We select galaxies undergoing gravitational instabilities using the number of clumps and degree of patchiness as proxies. The CANDELS visual classification system is used to identify 44 clumpy disk galaxies, along with mass-matched comparison samples of smooth and intermediate morphology galaxies. We note that despite being mass-matched and having similar star formation rates, the smoother galaxies tend to be smaller disks with more prominent bulges compared to the clumpy galaxies. The lack of smooth extended disks is probably a general feature of the z ∼ 2 galaxy population, and means we cannot directly compare with the clumpy and smooth extended disks observed at lower redshift. We find that z ∼ 2 clumpy galaxies have slightly enhanced AGN fractions selected by integrated line ratios (in the mass-excitation method), but the spatially resolved line ratios indicate this is likely due to extended phenomena rather than nuclear AGNs. Meanwhile, the X-ray data show that clumpy, smooth, and intermediate galaxies have nearly indistinguishable AGN fractions derived from both individual detections and stacked non-detections. The data demonstrate that AGN fueling modes at z ∼ 1.85—whether violent disk instabilities or secular processes—are as efficient in smooth galaxies as they are in clumpy galaxies.
ON THE 10 μm SILICATE FEATURE IN ACTIVE GALACTIC NUCLEI

International Nuclear Information System (INIS)

Nikutta, Robert; Elitzur, Moshe; Lacy, Mark

2009-01-01

The 10 μm silicate feature observed with Spitzer in active galactic nuclei (AGNs) reveals some puzzling behavior. It (1) has been detected in emission in type 2 sources, (2) shows broad, flat-topped emission peaks shifted toward long wavelengths in several type 1 sources, and (3) is not seen in deep absorption in any source observed so far. We solve all three puzzles with our clumpy dust radiative transfer formalism. Addressing (1), we present the spectral energy distribution (SED) of SST1721+6012, the first type 2 quasar observed to show a clear 10 μm silicate feature in emission. Such emission arises in models of the AGN torus easily when its clumpy nature is taken into account. We constructed a large database of clumpy torus models and performed extensive fitting of the observed SED. We find that the cloud radial distribution varies as r -1.5 and the torus contains 2-4 clouds along radial equatorial rays, each with optical depth at visual ∼60-80. The source bolometric luminosity is ∼3 x 10 12 L sun . Our modeling suggests that ∼<35% of objects with tori sharing these characteristics and geometry would have their central engines obscured. This relatively low obscuration probability can explain the clear appearance of the 10 μm emission feature in SST1721+6012 together with its rarity among other QSO2. Investigating (2), we also fitted the SED of PG1211+143, one of the first type 1 QSOs with a 10 μm silicate feature detected in emission. Together with other similar sources, this QSO appears to display an unusually broadened feature whose peak is shifted toward longer wavelengths. Although this led to suggestions of non-standard dust chemistry in these sources, our analysis fits such SEDs with standard galactic dust; the apparent peak shifts arise from simple radiative transfer effects. Regarding (3), we find additionally that the distribution of silicate feature strengths among clumpy torus models closely resembles the observed distribution, and the
On the 10 μm Silicate Feature in Active Galactic Nuclei

Science.gov (United States)

Nikutta, Robert; Elitzur, Moshe; Lacy, Mark

2009-12-01

The 10 μm silicate feature observed with Spitzer in active galactic nuclei (AGNs) reveals some puzzling behavior. It (1) has been detected in emission in type 2 sources, (2) shows broad, flat-topped emission peaks shifted toward long wavelengths in several type 1 sources, and (3) is not seen in deep absorption in any source observed so far. We solve all three puzzles with our clumpy dust radiative transfer formalism. Addressing (1), we present the spectral energy distribution (SED) of SST1721+6012, the first type 2 quasar observed to show a clear 10 μm silicate feature in emission. Such emission arises in models of the AGN torus easily when its clumpy nature is taken into account. We constructed a large database of clumpy torus models and performed extensive fitting of the observed SED. We find that the cloud radial distribution varies as r -1.5 and the torus contains 2-4 clouds along radial equatorial rays, each with optical depth at visual ~60-80. The source bolometric luminosity is ~3 × 1012 Lsun. Our modeling suggests that lsim35% of objects with tori sharing these characteristics and geometry would have their central engines obscured. This relatively low obscuration probability can explain the clear appearance of the 10 μm emission feature in SST1721+6012 together with its rarity among other QSO2. Investigating (2), we also fitted the SED of PG1211+143, one of the first type 1 QSOs with a 10 μm silicate feature detected in emission. Together with other similar sources, this QSO appears to display an unusually broadened feature whose peak is shifted toward longer wavelengths. Although this led to suggestions of non-standard dust chemistry in these sources, our analysis fits such SEDs with standard galactic dust; the apparent peak shifts arise from simple radiative transfer effects. Regarding (3), we find additionally that the distribution of silicate feature strengths among clumpy torus models closely resembles the observed distribution, and the feature
Hypercat - Hypercube of Clumpy AGN Tori

Science.gov (United States)

Nikutta, Robert; Lopez-Rodriguez, Enrique; Ichikawa, Kohei; Levenson, Nancy; Packham, Christopher C.

2017-06-01

Dusty tori surrounding the central engines of Active Galactic Nuclei (AGN) are required by the Unification Paradigm, and are supported by many observations, e.g. variable nuclear absorber (sometimes Compton-thick) in X-rays, reverberation mapping in optical/UV, hot dust emission and SED shapes in NIR/MIR, molecular and cool-dust tori observed with ALMA in sub-mm.While models of AGN torus SEDs have been developed and utilized for a long time, the study of the resolved emission morphology (brightness maps) has so far been under-appreciated, presumably because resolved observations of the central parsec in AGN are only possible very recently. Currently, only NIR+MIR interferometry is capable of resolving the nuclear dust emission (but not of producing images, until MATISSE comes online). Furthermore, MIR interferometry has delivered also puzzling results, e.g. that in some resolved sources the light emanates preferentially from polar directions above the "torus" system, and not from the equatorial plane, where most of the dust is located.We are preparing the release of a panchromatic, fully interpolable hypercube of brightness maps and projected dust images for a large number of CLUMPY torus models (Nenkova+2008), that will help facilitate studies of resolved AGN emission and dust morphologies. Together with the cube we will release a comprehensive set of open-source tools (Python) that will enable researches to work efficiently with this large hypercube:* easy sub-cube selection + memory-mapping (mitigating the too-big-for-RAM problem)* multi-dim image interpolation (get an image at any wavelength & model parameter combination)* simulation of observations with telescopes (compute/provide + apply a PSF) and interferometers (get visibilities)* analyze images with respect to the power contained at all scales and orientations (via 2D steerable wavelets), addressing the seemingly puzzling results mentioned aboveA series of papers is in preparation, aiming at solving the
EW[OIII] as an Orientation Indicator for Quasars: Implications for the Torus

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Bisogni, Susanna [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Osservatorio Astrofisico di Arcetri, INAF, Florence (Italy); Marconi, Alessandro; Risaliti, Guido [Osservatorio Astrofisico di Arcetri, INAF, Florence (Italy); Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Florence (Italy); Lusso, Elisabeta, E-mail: susanna.bisogni@cfa.harvard.edu [Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham (United Kingdom)

2017-11-21

We present an analysis of the average spectral properties of 12,000 SDSS quasars as a function of accretion disc inclination, as measured from the equivalent width of the [OIII] 5007Å line. The use of this indicator on a large sample of quasars from the SDSS DR7 has proven the presence of orientation effects on the features of UV/optical spectra, confirming the presence of outflows in the NLR gas and that the geometry of the BLR is disc-like. Relying on the goodness of this indicator, we are now using it to investigate other bands/components of AGN. Specifically, the study of the UV/optical/IR SED of the same sample provides information on the obscuring “torus.” The SED shows a decrease of the IR fraction moving from face-on to edge-on sources, in agreement with models where the torus is co-axial with the accretion disc. Moreover, the fact we are able to observe the broad emission lines also in sources in an edge-on position, suggests that the torus is rather clumpy than smooth as in the Unified Model. The behavior of the SED as a function of EW[OIII] is in agreement with the predictions of the clumpy torus models as well.
Modeling the Infrared Reverberation Response of the Circumnuclear Dusty Torus in AGNs: The Effects of Cloud Orientation and Anisotropic Illumination

International Nuclear Information System (INIS)

Almeyda, Triana; Robinson, Andrew; Richmond, Michael; Vazquez, Billy; Nikutta, Robert

2017-01-01

The obscuring circumnuclear torus of dusty molecular gas is one of the major components of active galactic nuclei (AGN). The torus can be studied by analyzing the time response of its infrared (IR) dust emission to variations in the AGN continuum luminosity, a technique known as reverberation mapping. The IR response is the convolution of the AGN ultraviolet/optical light curve with a transfer function that contains information about the size, geometry, and structure of the torus. Here, we describe a new computer model that simulates the reverberation response of a clumpy torus. Given an input optical light curve, the code computes the emission of a 3D ensemble of dust clouds as a function of time at selected IR wavelengths, taking into account light travel delays. We present simulated dust emission responses at 3.6, 4.5, and 30 μ m that explore the effects of various geometrical and structural properties, dust cloud orientation, and anisotropy of the illuminating radiation field. We also briefly explore the effects of cloud shadowing (clouds are shielded from the AGN continuum source). Example synthetic light curves have also been generated, using the observed optical light curve of the Seyfert 1 galaxy NGC 6418 as input. The torus response is strongly wavelength-dependent, due to the gradient in cloud surface temperature within the torus, and because the cloud emission is strongly anisotropic at shorter wavelengths. Anisotropic illumination of the torus also significantly modifies the torus response, reducing the lag between the IR and optical variations.
Modeling the Infrared Reverberation Response of the Circumnuclear Dusty Torus in AGNs: The Effects of Cloud Orientation and Anisotropic Illumination

Energy Technology Data Exchange (ETDEWEB)

Almeyda, Triana; Robinson, Andrew; Richmond, Michael; Vazquez, Billy [School of Physics and Astronomy, Rochester Institute of Technology, Rochester, NY 14623 (United States); Nikutta, Robert, E-mail: tra3595@rit.edu [National Optical Astronomy Observatory, 950 N Cherry Ave, Tucson, AZ 85719 (United States)

2017-07-01

The obscuring circumnuclear torus of dusty molecular gas is one of the major components of active galactic nuclei (AGN). The torus can be studied by analyzing the time response of its infrared (IR) dust emission to variations in the AGN continuum luminosity, a technique known as reverberation mapping. The IR response is the convolution of the AGN ultraviolet/optical light curve with a transfer function that contains information about the size, geometry, and structure of the torus. Here, we describe a new computer model that simulates the reverberation response of a clumpy torus. Given an input optical light curve, the code computes the emission of a 3D ensemble of dust clouds as a function of time at selected IR wavelengths, taking into account light travel delays. We present simulated dust emission responses at 3.6, 4.5, and 30 μ m that explore the effects of various geometrical and structural properties, dust cloud orientation, and anisotropy of the illuminating radiation field. We also briefly explore the effects of cloud shadowing (clouds are shielded from the AGN continuum source). Example synthetic light curves have also been generated, using the observed optical light curve of the Seyfert 1 galaxy NGC 6418 as input. The torus response is strongly wavelength-dependent, due to the gradient in cloud surface temperature within the torus, and because the cloud emission is strongly anisotropic at shorter wavelengths. Anisotropic illumination of the torus also significantly modifies the torus response, reducing the lag between the IR and optical variations.
Cooling Timescale of Dust Tori in Dying Active Galactic Nuclei

Energy Technology Data Exchange (ETDEWEB)

Ichikawa, Kohei [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Tazaki, Ryo, E-mail: k.ichikawa@astro.columbia.edu [Astronomical Institute, Tohoku University, 6-3 Aramaki, Aoba-ku, Sendai 980-8578 (Japan)

2017-07-20

We estimate the dust torus cooling timescale once the active galactic nucleus (AGN) is quenched. In a clumpy torus system, once the incoming photons are suppressed, the cooling timescale of one clump from T {sub dust} = 1000 K to several 10 K is less than 10 years, indicating that the dust torus cooling time is mainly governed by the light crossing time of the torus from the central engine. After considering the light crossing time of the torus, the AGN torus emission at 12 μ m becomes over two orders of magnitude fainter within 100 years after the quenching. We also propose that those “dying” AGNs could be found using the AGN indicators with a different physical scale R such as 12 μ m band luminosity tracing AGN torus ( R ∼ 10 pc) and the optical [O iii] λ 5007 emission line tracing narrow line regions ( R = 10{sup 2–4} pc).
The origin of the mid-infrared nuclear polarization of active galactic nuclei

Science.gov (United States)

Lopez-Rodriguez, E.; Alonso-Herrero, A.; Diaz-Santos, T.; Gonzalez-Martin, O.; Ichikawa, K.; Levenson, N. A.; Martinez-Paredes, M.; Nikutta, R.; Packham, C.; Perlman, E.; Almeida, C. Ramos; Rodriguez-Espinosa, J. M.; Telesco, C. M.

2018-05-01

We combine new (NGC 1275, NGC 4151, and NGC 5506) and previously published (Cygnus A, Mrk 231, and NGC 1068) sub-arcsecond resolution mid-infrared (MIR; 8-13 μm) imaging- and spectro-polarimetric observations of six Seyfert galaxies using CanariCam on the 10.4-m Gran Telescopio CANARIAS. These observations reveal a diverse set of physical processes responsible for the nuclear polarization, and permit characterization of the origin of the MIR nuclear polarimetric signature of active galactic nuclei (AGN). For all radio quiet objects, we found that the nuclear polarization is low (sensitivity to detect such extended emission (i.e., NGC 1068 and NGC 4151). We suggest that the higher degree of polarization previously found in lower resolution data arises only on the larger-than-nuclear scales. Only the radio-loud Cygnus A exhibits significant nuclear polarization (˜11 per cent), attributable to synchrotron emission from the pc-scale jet close to the core. We present polarization models that suggest that the MIR nuclear polarization for highly obscured objects arises from a self-absorbed MIR polarized clumpy torus and/or dichroism from the host galaxy, while for unabsorbed cores, MIR polarization arises from dust scattering in the torus and/or surrounding nuclear dust.
New Spectral Model for Constraining Torus Covering Factors from Broadband X-Ray Spectra of Active Galactic Nuclei

Science.gov (United States)

Baloković, M.; Brightman, M.; Harrison, F. A.; Comastri, A.; Ricci, C.; Buchner, J.; Gandhi, P.; Farrah, D.; Stern, D.

2018-02-01

The basic unified model of active galactic nuclei (AGNs) invokes an anisotropic obscuring structure, usually referred to as a torus, to explain AGN obscuration as an angle-dependent effect. We present a new grid of X-ray spectral templates based on radiative transfer calculations in neutral gas in an approximately toroidal geometry, appropriate for CCD-resolution X-ray spectra (FWHM ≥ 130 eV). Fitting the templates to broadband X-ray spectra of AGNs provides constraints on two important geometrical parameters of the gas distribution around the supermassive black hole: the average column density and the covering factor. Compared to the currently available spectral templates, our model is more flexible, and capable of providing constraints on the main torus parameters in a wider range of AGNs. We demonstrate the application of this model using hard X-ray spectra from NuSTAR (3–79 keV) for four AGNs covering a variety of classifications: 3C 390.3, NGC 2110, IC 5063, and NGC 7582. This small set of examples was chosen to illustrate the range of possible torus configurations, from disk-like to sphere-like geometries with column densities below, as well as above, the Compton-thick threshold. This diversity of torus properties challenges the simple assumption of a standard geometrically and optically thick toroidal structure commonly invoked in the basic form of the unified model of AGNs. Finding broad consistency between our constraints and those from infrared modeling, we discuss how the approach from the X-ray band complements similar measurements of AGN structures at other wavelengths.
Suzaku View of the Swift/BAT Active Galactic Nuclei. V. Torus Structure of Two Luminous Radio-Loud Active Galactic Nuclei (3C 206 and PKS 0707-35)

Science.gov (United States)

Tazaki, Fumie; Ueda, Yoshihiro; Terashima, Yuichi; Mushotzky, Richard F.; Tombesi, Francesco

2013-01-01

We present the results from broadband X-ray spectral analysis of 3C 206 and PKS 0707-35 with Suzaku and Swift/BAT, two of the most luminous unobscured and obscured radio-loud active galactic nuclei (AGNs) with hard X-ray luminosities of 10(sup 45.5) erg per second and 10(sup 44.9) erg per second (14-195 keV), respectively. Based on the radio core luminosity, we estimate that the X-ray spectrum of 3C 206 contains a significant (60% in the 14-195 keV band) contribution from the jet, while it is negligible in PKS 0707-35.We can successfully model the spectra with the jet component (for 3C 206), the transmitted emission, and two reflection components from the torus and the accretion disk. The reflection strengths from the torus are found to be R(sub torus)(=Omega/2pi) = 0.29 +/- 0.18 and 0.41 +/- 0.18 for 3C 206 and PKS 0707-35, respectively, which are smaller than those in typical Seyfert galaxies. Utilizing the torus model by Ikeda et al., we quantify the relation between the half-opening angle of a torus (theta(sub oa)) and the equivalent width of an iron-K line. The observed equivalent width of 3C 206, less than 71 eV, constrains the column density in the equatorial plane to N(sup eq)(sub H) lesst han 10(sup 23) per square centimeter, or the half-opening angle to theta(sub oa) greater than 80 deg. if N(sup eq)(sub H) = 10(sup 24) per square centimeter is assumed. That of PKS 0707-35, 72 +/- 36 eV, is consistent with N(sup eq)(sub H) 10(sup 23) per square centimeter. Our results suggest that the tori in luminous radio-loud AGNs are only poorly developed. The trend is similar to that seen in radio-quiet AGNs, implying that the torus structure is not different between AGNs with jets and without jets.
First X-ray Statistical Tests for Clumpy Torii Models: Constraints from RXTE monitoring of Seyfert AGN

Science.gov (United States)

Markowitz, A.

2015-09-01

We summarize two papers providing the first X-ray-derived statistical constraints for both clumpy-torus model parameters and cloud ensemble properties. In Markowitz, Krumpe, & Nikutta (2014), we explored multi-timescale variability in line-of-sight X-ray absorbing gas as a function of optical classification. We examined 55 Seyferts monitored with the Rossi X-ray Timing Explorer, and found in 8 objects a total of 12 eclipses, with durations between hours and years. Most clouds are commensurate with the outer portions of the BLR, or the inner regions of infrared-emitting dusty tori. The detection of eclipses in type Is disfavors sharp-edged tori. We provide probabilities to observe a source undergoing an absorption event for both type Is and IIs, yielding constraints in [N_0, sigma, i] parameter space. In Nikutta et al., in prep., we infer that the small cloud angular sizes, as seen from the SMBH, imply the presence of >10^7 clouds in BLR+torus to explain observed covering factors. Cloud size is roughly proportional to distance from the SMBH, hinting at the formation processes (e.g. disk fragmentation). All observed clouds are sub-critical with respect to tidal disruption; self-gravity alone cannot contain them. External forces (e.g. magnetic fields, ambient pressure) are needed to contain them, or otherwise the clouds must be short-lived. Finally, we infer that the radial cloud density distribution behaves as 1/r^{0.7}, compatible with VLTI observations. Our results span both dusty and non-dusty clumpy media, and probe model parameter space complementary to that for short-term eclipses observed with XMM-Newton, Suzaku, and Chandra.

TORUS AND ACTIVE GALACTIC NUCLEUS PROPERTIES OF NEARBY SEYFERT GALAXIES: RESULTS FROM FITTING INFRARED SPECTRAL ENERGY DISTRIBUTIONS AND SPECTROSCOPY

International Nuclear Information System (INIS)

Alonso-Herrero, Almudena; Ramos Almeida, Cristina; Mason, Rachel; Asensio Ramos, Andres; Rodriguez Espinosa, Jose Miguel; Perez-Garcia, Ana M.; Roche, Patrick F.; Levenson, Nancy A.; Elitzur, Moshe; Packham, Christopher; Young, Stuart; Diaz-Santos, Tanio

2011-01-01

We used the CLUMPY torus models and a Bayesian approach to fit the infrared spectral energy distributions and ground-based high angular resolution mid-infrared spectroscopy of 13 nearby Seyfert galaxies. This allowed us to put tight constraints on torus model parameters such as the viewing angle i, the radial thickness of the torus Y, the angular size of the cloud distribution σ torus , and the average number of clouds along radial equatorial rays N 0 . We found that the viewing angle i is not the only parameter controlling the classification of a galaxy into type 1 or type 2. In principle, type 2s could be viewed at any viewing angle i as long as there is one cloud along the line of sight. A more relevant quantity for clumpy media is the probability for an active galactic nucleus (AGN) photon to escape unabsorbed. In our sample, type 1s have relatively high escape probabilities, P esc ∼ 12%-44%, while type 2s, as expected, tend to have very low escape probabilities. Our fits also confirmed that the tori of Seyfert galaxies are compact with torus model radii in the range 1-6 pc. The scaling of the models to the data also provided the AGN bolometric luminosities L bol (AGN), which were found to be in good agreement with estimates from the literature. When we combined our sample of Seyfert galaxies with a sample of PG quasars from the literature to span a range of L bol (AGN) ∼ 10 43 -10 47 erg s -1 , we found plausible evidence of the receding torus. That is, there is a tendency for the torus geometrical covering factor to be lower (f 2 ∼ 0.1-0.3) at high AGN luminosities than at low AGN luminosities (f 2 ∼ 0.9-1 at ∼10 43 -10 44 erg s -1 ). This is because at low AGN luminosities the tori appear to have wider angular sizes (larger σ torus ) and more clouds along radial equatorial rays. We cannot, however, rule out the possibility that this is due to contamination by extended dust structures not associated with the dusty torus at low AGN luminosities
Science of active galactic nuclei with the GTC and CanariCam

Science.gov (United States)

Levenson, Nancy A.; Packham, Christopher C.; Alonso-Herrero, Almudena; Aretxaga, Itziar; Colina, Luis; Díaz-Santos, Tanio; Elitzur, Moshe; Mason, Rachel E.; Perlman, Eric S.; Radomski, James T.; Roche, Patrick F.; Rodríguez Espinosa, José Miguel; Young, Stuart; Telesco, Charles M.

2008-07-01

CanariCam is the facility mid-infrared (MIR) instrument for the Gran Telescopio Canarias (GTC), a 10.4m telescope at the Observatorio del Roque de los Muchachos on La Palma. One of the science drivers for CanariCam is the study of active galactic nuclei (AGN). We will exploit the instrument's high sensitivity in imaging, spectroscopy, and polarimetry modes to answer fundamental questions of AGN and their host galaxies. Dust in the nucleus of an active galaxy reprocesses the intrinsic radiation of the central engine to emerge in the MIR. Current work demonstrates that the hot dust immediately associated with the AGN, which blocks direct views of the AGN from some lines of sight, is confined to small (parsec) scales. Thus, high spatial resolution is essential to probe the "torus" of unified AGN models separate from the host galaxy. CanariCam provides a 0.08" pixel scale for Nyquist sampling the diffraction-limited point spread function at 8μm, and narrow (0.2") spectroscopy slits (with R=120-1300). New observations with the GTC/CanariCam will provide key constraints on the physical conditions in the clumpy torus, and we will sensitively determine AGN obscuration as a function of nuclear activity. We will therefore address the fueling process and its relationship to the torus, the interaction with the host galaxy, and dust chemistry. These data will be essential preparation for the next generation of telescopes that will observe the distant universe directly to explore galaxy and black hole formation and evolution, and the GTC/CanariCam system uniquely provides multiple modes to probe AGN.
Torus theory

International Nuclear Information System (INIS)

Namsrai, Kh.

2001-11-01

Geometrical structure and physical characteristics of a torus are investigated in detail. Newtonian and electromagnetic potentials of the torus are defined at short and long distances. It is shown that torus potential at small distances has attractive oscillator behaviour. Motion of a particle in the torus potential is studied. The inertia tensor of the torus and its dynamics are obtained. Rotating torus whose tip is held fixed by two massless rigid threads and moves in a gravitational field is considered. (author)
TORUS Annual Continuation and Progress Report

Energy Technology Data Exchange (ETDEWEB)

Arbanas, Goran [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Elster, Charlotte [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Echer, Jutta [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nunes, Filomena [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Thompson, Ian [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2014-02-24

The TORUS collaboration derives its name from the research it focuses on, namely the Theory of Reactions for Unstable iSotopes. It is a Topical Collaboration in Nuclear Theory, and funded by the Nuclear Theory Division of the Office of Nuclear Physics in the Office of Science of the Department of Energy. The funding supports one postdoctoral researcher for the years 1 through 4. The collaboration brings together as Principal Investigators a large fraction of the nuclear reaction theorists currently active within the USA. The mission of the TORUS Topical Collaboration is to develop new methods that will advance nuclear reaction theory for unstable isotopes by using three-body techniques to improve directreaction calculations. This multi-institution collaborative effort is directly relevant to three areas of interest: the properties of nuclei far from stability; microscopic studies of nuclear input parameters for astrophysics, and microscopic nuclear reaction theory.
Accretion disks in active galactic nuclei

International Nuclear Information System (INIS)

Begelman, M.C.

1985-01-01

The innermost regions of the central engines in active galactic nuclei are examined, and it is shown how different modes of accretion with angular momentum may account for the diverse manifestations of activity in the nuclei of galaxies. These modes are subsequently compared with the observed properties of quasars, Type I Seyferts, and radio galaxies. It was found that the qualitative features of an accretion flow orbiting a massive black hole depend principally on the ratio of the actual accretion rate to the Eddington accretion rate. For a value of this ratio much less than one, the flow may become an ion torus supported by gas pressure; for a value much greater than one, the flow traps its radiative output and becomes an inefficient radiation torus. At intermediate values, the flow may settle into a thin accretion disk. 62 references
ORIGINAL ARTICLE Torus Palatinus and Torus Mandibularis in a ...

African Journals Online (AJOL)

Ogunbodede

; 28:105-111. 4. Seah, Y. H. Torus Palatinus and. Torus Mandibularis: a Review of the Literature. Aust. Dent. J. 1995;. 40:318-321. 5. Bernal, B. A.; Moreira, D. E.;. Rodriguez, P., I [Prevalence of. Torus Palatinus and Torus. Mandibularis in the ...
Jet-torus connection in radio galaxies. Relativistic hydrodynamics and synthetic emission

Science.gov (United States)

Fromm, C. M.; Perucho, M.; Porth, O.; Younsi, Z.; Ros, E.; Mizuno, Y.; Zensus, J. A.; Rezzolla, L.

2018-01-01

Context. High resolution very long baseline interferometry observations of active galactic nuclei have revealed asymmetric structures in the jets of radio galaxies. These asymmetric structures may be due to internal asymmetries in the jets or they may be induced by the different conditions in the surrounding ambient medium, including the obscuring torus, or a combination of the two. Aims: In this paper we investigate the influence of the ambient medium, including the obscuring torus, on the observed properties of jets from radio galaxies. Methods: We performed special-relativistic hydrodynamic (SRHD) simulations of over-pressured and pressure-matched jets using the special-relativistic hydrodynamics code Ratpenat, which is based on a second-order accurate finite-volume method and an approximate Riemann solver. Using a newly developed radiative transfer code to compute the electromagnetic radiation, we modelled several jets embedded in various ambient medium and torus configurations and subsequently computed the non-thermal emission produced by the jet and thermal absorption from the torus. To better compare the emission simulations with observations we produced synthetic radio maps, taking into account the properties of the observatory. Results: The detailed analysis of our simulations shows that the observed properties such as core shift could be used to distinguish between over-pressured and pressure matched jets. In addition to the properties of the jets, insights into the extent and density of the obscuring torus can be obtained from analyses of the single-dish spectrum and spectral index maps.
TORUS: Theory of Reactions for Unstable iSotopes.Topical Collaboration for Nuclear Theory Project. Period: June 1, 2010 - May 31, 2015

Energy Technology Data Exchange (ETDEWEB)

Arbanas, Goran [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Elster, Charlotte [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Escher, Jutta [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nunes, Filomena [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Thompson, Ian [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2015-08-28

The work of this collaboration during its existence is summarized. The mission of the TORUS Topical Collaboration was to develop new methods that advance nuclear reaction theory for unstable isotopes by using three-body techniques to improve direct reaction calculations. This multi-institution collaborative effort was and remains directly relevant to three areas of interest: the properties of nuclei far from stability, microscopic studies of nuclear input parameters for astrophysics, and microscopic nuclear reaction theory. The TORUS project focused on understanding the details of (d,p) reactions for neutron transfer to heavier nuclei. The bulk of the work fell into three areas: coupled channel theory, modeling (d,p) reactions with a Faddeev-AGS approach, and capture reactions.
Suzaku Observations of Heavily Obscured (Compton-thick) Active Galactic Nuclei Selected by the Swift/BAT Hard X-Ray Survey

Science.gov (United States)

Tanimoto, Atsushi; Ueda, Yoshihiro; Kawamuro, Taiki; Ricci, Claudio; Awaki, Hisamitsu; Terashima, Yuichi

2018-02-01

We present a uniform broadband X-ray (0.5–100.0 keV) spectral analysis of 12 Swift/Burst Alert Telescope selected Compton-thick ({log}{N}{{H}}/{{cm}}-2≥slant 24) active galactic nuclei (CTAGNs) observed with Suzaku. The Suzaku data of three objects are published here for the first time. We fit the Suzaku and Swift spectra with models utilizing an analytic reflection code and those utilizing the Monte-Carlo-based model from an AGN torus by Ikeda et al. The main results are as follows: (1) The estimated intrinsic luminosity of a CTAGN strongly depends on the model; applying Compton scattering to the transmitted component in an analytic model may largely overestimate the intrinsic luminosity at large column densities. (2) Unabsorbed reflection components are commonly observed, suggesting that the tori are clumpy. (3) Most of CTAGNs show small scattering fractions (<0.5%), implying a buried AGN nature. (4) Comparison with the results obtained for Compton-thin AGNs suggests that the properties of these CTAGNs can be understood as a smooth extension from Compton-thin AGNs with heavier obscuration; we find no evidence that the bulk of the population of hard-X-ray-selected CTAGNs are different from less obscured objects.
The NuSTAR View of Nearby Compton-thick Active Galactic Nuclei: The Cases of NGC 424, NGC 1320, and IC 2560

Energy Technology Data Exchange (ETDEWEB)

Baloković, M.; Comastri, A.; Harrison, F. A.; Alexander, D. M.; Ballantyne, D. R.; Bauer, F. E.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Craig, W. W.; Moro, A. Del; Gandhi, P.; Hailey, C. J.; Koss, M.; Lansbury, G. B.; Luo, B.; Madejski, G. M.; Marinucci, A.; Matt, G.; Markwardt, C. B.; Puccetti, S.; Reynolds, C. S.; Risaliti, G.; Rivers, E.; Stern, D.; Walton, D. J.; Zhang, W. W.

2014-09-30

We present X-ray spectral analyses for three Seyfert 2 active galactic nuclei, NGC 424, NGC 1320, and IC 2560, observed by NuSTAR in the 3-79 keV band. The high quality hard X-ray spectra allow detailed modeling of the Compton reflection component for the first time in these sources. Using quasi-simultaneous NuSTAR and Swift/XRT data, as well as archival XMM-Newton data, we find that all three nuclei are obscured by Compton-thick material with column densities in excess of ~ 5 x 10²⁴ cm-², and that their X-ray spectra above 3 keV are dominated by reflection of the intrinsic continuum on Compton-thick material. Due to the very high obscuration, absorbed intrinsic continuum components are not formally required by the data in any of the sources. We constrain the intrinsic photon indices and the column density of the reflecting medium through the shape of the reflection spectra. Using archival multi-wavelength data we recover the intrinsic X-ray luminosities consistent with the broadband spectral energy distributions. Our results are consistent with the reflecting medium being an edge-on clumpy torus with a relatively large global covering factor and overall reflection efficiency of the order of 1%. Given the unambiguous confirmation of the Compton-thick nature of the sources, we investigate whether similar sources are likely to be missed by commonly used selection criteria for Compton-thick AGN, and explore the possibility of finding their high-redshift counterparts.
GPU-BASED MONTE CARLO DUST RADIATIVE TRANSFER SCHEME APPLIED TO ACTIVE GALACTIC NUCLEI

International Nuclear Information System (INIS)

Heymann, Frank; Siebenmorgen, Ralf

2012-01-01

A three-dimensional parallel Monte Carlo (MC) dust radiative transfer code is presented. To overcome the huge computing-time requirements of MC treatments, the computational power of vectorized hardware is used, utilizing either multi-core computer power or graphics processing units. The approach is a self-consistent way to solve the radiative transfer equation in arbitrary dust configurations. The code calculates the equilibrium temperatures of two populations of large grains and stochastic heated polycyclic aromatic hydrocarbons. Anisotropic scattering is treated applying the Heney-Greenstein phase function. The spectral energy distribution (SED) of the object is derived at low spatial resolution by a photon counting procedure and at high spatial resolution by a vectorized ray tracer. The latter allows computation of high signal-to-noise images of the objects at any frequencies and arbitrary viewing angles. We test the robustness of our approach against other radiative transfer codes. The SED and dust temperatures of one- and two-dimensional benchmarks are reproduced at high precision. The parallelization capability of various MC algorithms is analyzed and included in our treatment. We utilize the Lucy algorithm for the optical thin case where the Poisson noise is high, the iteration-free Bjorkman and Wood method to reduce the calculation time, and the Fleck and Canfield diffusion approximation for extreme optical thick cells. The code is applied to model the appearance of active galactic nuclei (AGNs) at optical and infrared wavelengths. The AGN torus is clumpy and includes fluffy composite grains of various sizes made up of silicates and carbon. The dependence of the SED on the number of clumps in the torus and the viewing angle is studied. The appearance of the 10 μm silicate features in absorption or emission is discussed. The SED of the radio-loud quasar 3C 249.1 is fit by the AGN model and a cirrus component to account for the far-infrared emission.
U3 snoRNP associates with fibrillarin a component of the scleroderma clumpy nucleolar domain

DEFF Research Database (Denmark)

Herrera-Esparza, Rafael; Kruse, Lars; von Essen, Marina

2002-01-01

by ELISA was recognized by the clumpy scleroderma serum from the majority of patients. In situ hybridization assays showed that the fibrillarin tagged by the elicited antibodies was colocalized with U3 snoRNP in the nucleolus in a clumpy manner and coprecipitated the U3 snoRNP. In conclusion...
Collective effects in shock propagation through a clumpy medium

International Nuclear Information System (INIS)

Norman, M.L.; Dickel, J.R.; Livio, M.; Chu, Y.H.

1988-01-01

A numerical simulation of shock propagation in a clumpy medium with a weak magnetic field is presented which illustrates a number of dynamical processes of potential importance for explaining spectral line width and radio polarization measurements in supernova remnants
Testing the AGN Unification Model in the Infrared

International Nuclear Information System (INIS)

Ramos Almeida, C; Levenson, N A; Radomski, J T; Alonso-Herrero, A; Asensio Ramos, A; Rodríguez Espinosa, J M; Pérez García, A M; Packham, C; Mason, R; Díaz-Santos, T

2012-01-01

We present near-to-mid-infrared spectral energy distributions (SEDs) for 21 Seyfert galaxies, using subarcsecond resolution imaging data. Our aim is to compare the properties Seyfert 1 (Sy1) and Seyfert 2 (Sy2) tori using clumpy torus models and a Bayesian approach to fit the infrared (IR) nuclear SEDs. These dusty tori have physical sizes smaller than 6 pc radius, as derived from our fits. Active galactic nuclei (AGN) unification schemes account for a variety of observational differences in terms of viewing geometry. However, we find evidence that strong unification may not hold, and that the immediate dusty surroundings of Sy1 and Sy2 nuclei are intrinsically different. The Type 2 tori studied here are broader, have more clumps, and these clumps have lower optical depths than those of Type 1 tori. The larger the covering factor of the torus, the smaller the probability of having direct view of the AGN, and vice-versa. In our sample, Sy2 tori have larger covering factors (C T = 0.95±0.02) and smaller escape probabilities than those of Sy1 (C T = 0.5±0.1). Thus, on the basis of the results presented here, the classification of a Seyfert galaxy may depend more on the intrinsic properties of the torus rather than on its mere inclination, in contradiction with the simplest unification model.
Torus Breakdown in Noninvertible Maps

DEFF Research Database (Denmark)

Maistrenko, V.; Maistrenko, Yu.; Mosekilde, Erik

2003-01-01

We propose a criterion for the destruction of a two-dimensional torus through the formation of an infinite set of cusp points on the closed invariant curves defining the resonance torus. This mechanism is specific to noninvertible maps. The cusp points arise when the tangent to the torus at the p......We propose a criterion for the destruction of a two-dimensional torus through the formation of an infinite set of cusp points on the closed invariant curves defining the resonance torus. This mechanism is specific to noninvertible maps. The cusp points arise when the tangent to the torus...... at the point of intersection with the critical curve L-0 coincides with the eigendirection corresponding to vanishing eigenvalue for the noninvertible map. Further parameter changes lead typically to the generation of loops (self-intersections of the invariant manifolds) followed by the transformation...
Extinction and dust properties in a clumpy medium

OpenAIRE

Scicluna, P.; Siebenmorgen, R.

2015-01-01

(abridged) The dust content of the universe is primarily explored via its interaction with stellar photons, producing interstellar extinction. However, owing to the physical extension of the observing beam, observations may detect scattered photons, resulting in a change in the observed (or effective) extinction, depending on the spatial distribution of the dust and the resolution of the instrument. We investigate the influence of clumpy dust distributions on effective extinction toward embed...
The Bumpy Torus Experiment

International Nuclear Information System (INIS)

Cobble, James Allen

2016-01-01

This document summarizes the Bumpy Torus Experiment as a viable fusion reactor concept. Conclusions reached include the following: In 30 years, order-of-magnitude technological advances have occurred in multiple areas of plasma heating and confinement. The ORNL bumpy torus of the 1970s was technology limited. Now that ITER is technology limited, an alternate concept is needed. A device built on such a concept should be current free, CW, modular, have a gentle shutdown, and demonstrable stability. The bumpy torus meets or has the potential to meet all of these criteria. Earlier, stability was not possible due to power limits; it has not been fully tested. It is time to revisit the bumpy-torus concept with a modest new machine.
The Bumpy Torus Experiment

Energy Technology Data Exchange (ETDEWEB)

Cobble, James Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-06-09

This document summarizes the Bumpy Torus Experiment as a viable fusion reactor concept. Conclusions reached include the following: In 30 years, order-of-magnitude technological advances have occurred in multiple areas of plasma heating and confinement. The ORNL bumpy torus of the 1970s was technology limited. Now that ITER is technology limited, an alternate concept is needed. A device built on such a concept should be current free, CW, modular, have a gentle shutdown, and demonstrable stability. The bumpy torus meets or has the potential to meet all of these criteria. Earlier, stability was not possible due to power limits; it has not been fully tested. It is time to revisit the bumpy-torus concept with a modest new machine.
Self-consistent two-phase AGN torus models⋆. SED library for observers

Science.gov (United States)

Siebenmorgen, Ralf; Heymann, Frank; Efstathiou, Andreas

2015-11-01

We assume that dust near active galactic nuclei (AGNs) is distributed in a torus-like geometry, which can be described as a clumpy medium or a homogeneous disk, or as a combination of the two (i.e. a two-phase medium). The dust particles considered are fluffy and have higher submillimeter emissivities than grains in the diffuse interstellar medium. The dust-photon interaction is treated in a fully self-consistent three-dimensional radiative transfer code. We provide an AGN library of spectral energy distributions (SEDs). Its purpose is to quickly obtain estimates of the basic parameters of the AGNs, such as the intrinsic luminosity of the central source, the viewing angle, the inner radius, the volume filling factor and optical depth of the clouds, and the optical depth of the disk midplane, and to predict the flux at yet unobserved wavelengths. The procedure is simple and consists of finding an element in the library that matches the observations. We discuss the general properties of the models and in particular the 10 μm silicate band. The AGN library accounts well for the observed scatter of the feature strengths and wavelengths of the peak emission. AGN extinction curves are discussed and we find that there is no direct one-to-one link between the observed extinction and the wavelength dependence of the dust cross sections. We show that objects in the library cover the observed range of mid-infrared colors of known AGNs. The validity of the approach is demonstrated by matching the SEDs of a number of representative objects: Four Seyferts and two quasars for which we present new Herschel photometry, two radio galaxies, and one hyperluminous infrared galaxy. Strikingly, for the five luminous objects we find that pure AGN models fit the SED without needing to postulate starburst activity. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.The SED
Active galactic nuclei. From the central engine to the host galaxy

International Nuclear Information System (INIS)

Gilbert, Didier

2008-01-01

After some recalls on galaxies, on their classification, on the Universe expansion and on the Hubble law, this academic report addresses active galactic nuclei (AGN) by describing their anatomy (central black hole, accretion disk, jets and winds, Broad Line Region, Narrow Line Region, molecular torus and dusts, radio lobes). The author also presents the unified model. In the next part, he proposes an overview of active galaxies and active galactic nuclei by distinguishing galaxies with a strong stellar activity, radio-quiet and radio-loud active galactic nuclei. Examples are presented for each of these types. In the last part, the author draws perspectives for research in cosmology, and outlines questions which are still to be answered

CLUMPY AND EXTENDED STARBURSTS IN THE BRIGHTEST UNLENSED SUBMILLIMETER GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Iono, Daisuke; Hatsukade, Bunyo; Kawabe, Ryohei; Matsuda, Yuichi; Nakanishi, Kouichiro [National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Yun, Min S.; Wilson, Grant [University of Massachusetts, Department of Astronomy, 710 North Pleasant Street, Amherst, MA 01003 (United States); Aretxaga, Itziar; Hughes, David [Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Luis Enrique Erro 1, Sta. Ma. Tonantzintla, Puebla (Mexico); Ikarashi, Soh [Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700AV Groningen (Netherlands); Izumi, Takuma; Kohno, Kotaro; Tamura, Yoichi; Umehata, Hideki [Institute of Astronomy, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Lee, Minju; Saito, Toshiki [Department of Astronomy, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 133-0033 (Japan); Ueda, Junko [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Michiyama, Tomonari; Ando, Misaki, E-mail: d.iono@nao.ac.jp [SOKENDAI (The Graduate University for Advanced Studies), 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

2016-09-20

The central structure in three of the brightest unlensed z = 3–4 submillimeter galaxies is investigated through 0.″015–0.″05 (120–360 pc) 860 μ m continuum images obtained using the Atacama Large Millimeter/submillimeter Array (ALMA). The distribution in the central kiloparsec in AzTEC1 and AzTEC8 is extremely complex, and they are composed of multiple ∼200 pc clumps. AzTEC4 consists of two sources that are separated by ∼1.5 kpc, indicating a mid-stage merger. The peak star formation rate densities in the central clumps are ∼300–3000 M {sub ⊙} yr{sup −1} kpc{sup −2}, suggesting regions with extreme star formation near the Eddington limit. By comparing the flux obtained by ALMA and Submillimeter Array, we find that 68%–90% of the emission is extended (≳1 kpc) in AzTEC4 and 8. For AzTEC1, we identify at least 11 additional compact (∼200 pc) clumps in the extended 3–4 kpc region. Overall, the data presented here suggest that the luminosity surface densities observed at ≲150 pc scales are roughly similar to that observed in local ULIRGs, as in the eastern nucleus of Arp 220. Between 10% and 30% of the 860 μ m continuum is concentrated in clumpy structures in the central kiloparsec, while the remaining flux is distributed over ≳1 kpc regions, some of which could also be clumpy. These sources can be explained by a rapid inflow of gas such as a merger of gas-rich galaxies, surrounded by extended and clumpy starbursts. However, the cold mode accretion model is not ruled out.
Torus type thermonuclear device

International Nuclear Information System (INIS)

Imura, Yasuya.

1979-01-01

Purpose: To attain supporting effect against electromagnetic force and moderate the inner stress applied to toroidal coils due to thermal expansion by intervening a stress relaxation member between the outer circumferential side of a torus and a support device in toroidal coils. Constitution: Toroidal coils for confining a plasma within a torus vacuum container is supported on a support secured to upper and lower bases. A thermoplastic stress relaxation material of a low young's modulus is put between the outer circumferential side of the torus container and the torus outer circumferential side of the support in the toroidal coil. Thermoplastic resin is best suited to the stress relaxation substance, although tetrafluoro resin may be used as the stress relaxation substance while packing non-woven tetron fabric or non-woven glass fabric impregnated with varnish in a gap between the stress relaxation substance and the support or the toroidal coils. (Seki, T.)
Compact magnetic confinement fusion: Spherical torus and compact torus

Directory of Open Access Journals (Sweden)

Zhe Gao

2016-05-01

Full Text Available The spherical torus (ST and compact torus (CT are two kinds of alternative magnetic confinement fusion concepts with compact geometry. The ST is actually a sub-category of tokamak with a low aspect ratio; while the CT is a toroidal magnetic configuration with a simply-connected geometry including spheromak and field reversed pinch. The ST and CT have potential advantages for ultimate fusion reactor; while at present they can also provide unique fusion science and technology contributions for mainstream fusion research. However, some critical scientific and technology issues should be extensively investigated.
National Spherical Torus Experiment (NSTX) Torus Design, Fabrication and Assembly

International Nuclear Information System (INIS)

Neumeyer, C.; Barnes, G.; Chrzanowski, J.H.; Heitzenroeder, P.

1999-01-01

The National Spherical Torus Experiment (NSTX) is a low aspect ratio spherical torus (ST) located at Princeton Plasma Physics Laboratory (PPPL). Fabrication, assembly, and initial power tests were completed in February of 1999. The majority of the design and construction efforts were constructed on the Torus system components. The Torus system includes the centerstack assembly, external Poloidal and Toroidal coil systems, vacuum vessel, torus support structure and plasma facing components (PFC's). NSTX's low aspect ratio required that the centerstack be made with the smallest radius possible. This, and the need to bake NSTXs carbon-carbon composite plasma facing components at 350 degrees C, was major drivers in the design of NSTX. The Centerstack Assembly consists of the inner legs of the Toroidal Field (TF) windings, the Ohmic Heating (OH) solenoid and its associated tension cylinder, three inner Poloidal Field (PF) coils, thermal insulation, diagnostics and an Inconel casing which forms the inner wall of the vacuum vessel boundary. It took approximately nine months to complete the assembly of the Centerstack. The tight radial clearances and the extreme length of the major components added complexity to the assembly of the Centerstack components. The vacuum vessel was constructed of 304-stainless steel and required approximately seven months to complete and deliver to the Test Cell. Several of the issues associated with the construction of the vacuum vessel were control of dimensional stability following welding and controlling the permeability of the welds. A great deal of time and effort was devoted to defining the correct weld process and material selection to meet our design requirements. The PFCs will be baked out at 350 degrees C while the vessel is maintained at 150 degrees C. This required care in designing the supports so they can accommodate the high electromagnetic loads resulting from plasma disruptions and the resulting relative thermal expansions
Torus-doubling process via strange nonchaotic attractors

International Nuclear Information System (INIS)

Mitsui, Takahito; Uenohara, Seiji; Morie, Takashi; Horio, Yoshihiko; Aihara, Kazuyuki

2012-01-01

Torus-doubling bifurcations typically occur only a finite number of times. It has been assumed that torus-doubling bifurcations in quasiperiodically forced systems are interrupted by the appearance of strange nonchaotic attractors (SNAs). In the present Letter, we study a quasiperiodically forced noninvertible map and report the occurrence of a torus-doubling process via SNAs. The mechanism of this process is numerically clarified. Furthermore, this process is experimentally demonstrated in a switched-capacitor integrated circuit. -- Highlights: ► We report the occurrence of a torus-doubling process via strange nonchaotic attractors (SNAs). ► The process consists of the gradual fractalization of a torus and the Heagy–Hammel transition. ► The torus-doubling process via SNAs is also experimentally demonstrated in an electronic circuit.
THE NUCLEAR INFRARED EMISSION OF LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI

Energy Technology Data Exchange (ETDEWEB)

Mason, R. E. [Gemini Observatory, Northern Operations Center, 670 N. A' ohoku Place, Hilo, HI 96720 (United States); Lopez-Rodriguez, E.; Packham, C. [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, P.O. Box 112055, Gainesville, FL 32611 (United States); Alonso-Herrero, A. [Instituto de Fisica de Cantabria, CSIC-UC, Avenida de los Castros s/n, 39005 Santander (Spain); Levenson, N. A.; Radomski, J. [Gemini Observatory, Southern Operations Center, c/o AURA, Casilla 603, La Serena (Chile); Ramos Almeida, C. [Instituto de Astrofisica de Canarias, C/Via Lactea, s/n, E-38205, La Laguna, Tenerife (Spain); Colina, L. [Departamento de Astrofisica, Centro de Astrobiologia (CSIC/INTA), Instituto Nacional de Tecnica Aeroespacial, Crta de Torrejon a Ajalvir, km 4, 28850 Torrejon de Ardoz, Madrid (Spain); Elitzur, M. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States); Aretxaga, I. [Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Aptdo. Postal 51 y 216, 72000 Puebla (Mexico); Roche, P. F. [Astrophysics, Department of Physics, University of Oxford, DWB, Keble Road, Oxford OX1 3RH (United Kingdom); Oi, N. [Department of Astronomy, School of Science, Graduate University for Advanced Studies (SOKENDAI), Mitaka, Tokyo 181-8588 (Japan)

2012-07-15

We present high-resolution mid-infrared (MIR) imaging, nuclear spectral energy distributions (SEDs), and archival Spitzer spectra for 22 low-luminosity active galactic nuclei (LLAGNs; L{sub bol} {approx}< 10{sup 42} erg s{sup -1}). Infrared (IR) observations may advance our understanding of the accretion flows in LLAGNs, the fate of the obscuring torus at low accretion rates, and, perhaps, the star formation histories of these objects. However, while comprehensively studied in higher-luminosity Seyferts and quasars, the nuclear IR properties of LLAGNs have not yet been well determined. We separate the present LLAGN sample into three categories depending on their Eddington ratio and radio emission, finding different IR characteristics for each class. (1) At the low-luminosity, low-Eddington-ratio (log L{sub bol}/L{sub Edd} < -4.6) end of the sample, we identify 'host-dominated' galaxies with strong polycyclic aromatic hydrocarbon bands that may indicate active (circum-)nuclear star formation. (2) Some very radio-loud objects are also present at these low Eddington ratios. The IR emission in these nuclei is dominated by synchrotron radiation, and some are likely to be unobscured type 2 AGNs that genuinely lack a broad-line region. (3) At higher Eddington ratios, strong, compact nuclear sources are visible in the MIR images. The nuclear SEDs of these galaxies are diverse; some resemble typical Seyfert nuclei, while others lack a well-defined MIR 'dust bump'. Strong silicate emission is present in many of these objects. We speculate that this, together with high ratios of silicate strength to hydrogen column density, could suggest optically thin dust and low dust-to-gas ratios, in accordance with model predictions that LLAGNs do not host a Seyfert-like obscuring torus. We anticipate that detailed modeling of the new data and SEDs in terms of accretion disk, jet, radiatively inefficient accretion flow, and torus components will provide further
A Game of Hide and Seek: Expectations of Clumpy Resources Influence Hiding and Searching Patterns.

Directory of Open Access Journals (Sweden)

Andreas Wilke

Full Text Available Resources are often distributed in clumps or patches in space, unless an agent is trying to protect them from discovery and theft using a dispersed distribution. We uncover human expectations of such spatial resource patterns in collaborative and competitive settings via a sequential multi-person game in which participants hid resources for the next participant to seek. When collaborating, resources were mostly hidden in clumpy distributions, but when competing, resources were hidden in more dispersed (random or hyperdispersed patterns to increase the searching difficulty for the other player. More dispersed resource distributions came at the cost of higher overall hiding (as well as searching times, decreased payoffs, and an increased difficulty when the hider had to recall earlier hiding locations at the end of the experiment. Participants' search strategies were also affected by their underlying expectations, using a win-stay lose-shift strategy appropriate for clumpy resources when searching for collaboratively-hidden items, but moving equally far after finding or not finding an item in competitive settings, as appropriate for dispersed resources. Thus participants showed expectations for clumpy versus dispersed spatial resources that matched the distributions commonly found in collaborative versus competitive foraging settings.
Torus knots and mirror symmetry

CERN Document Server

Brini, Andrea; Marino, Marcos

2012-01-01

We propose a spectral curve describing torus knots and links in the B-model. In particular, the application of the topological recursion to this curve generates all their colored HOMFLY invariants. The curve is obtained by exploiting the full Sl(2, Z) symmetry of the spectral curve of the resolved conifold, and should be regarded as the mirror of the topological D-brane associated to torus knots in the large N Gopakumar-Vafa duality. Moreover, we derive the curve as the large N limit of the matrix model computing torus knot invariants.
Towards a physical model of dust tori in Active Galactic Nuclei. Radiative transfer calculations for a hydrostatic torus model

Science.gov (United States)

Schartmann, M.; Meisenheimer, K.; Camenzind, M.; Wolf, S.; Henning, Th.

2005-07-01

We explore physically self-consistent models of dusty molecular tori in Active Galactic Nuclei (AGN) with the goal of interpreting VLTI observations and fitting high resolution mid-IR spectral energy distributions (SEDs). The input dust distribution is analytically calculated by assuming hydrostatic equilibrium between pressure forces - due to the turbulent motion of the gas clouds - and gravitational and centrifugal forces as a result of the contribution of the nuclear stellar distribution and the central black hole. For a fully three-dimensional treatment of the radiative transfer problem through the tori we employ the Monte Carlo code MC3D. We find that in homogeneous dust distributions the observed mid-infrared emission is dominated by the inner funnel of the torus, even when observing along the equatorial plane. Therefore, the stratification of the distribution of dust grains - both in terms of size and composition - cannot be neglected. In the current study we only include the effect of different sublimation radii which significantly alters the SED in comparison to models that assume an average dust grain property with a common sublimation radius, and suppresses the silicate emission feature at 9.7~μm. In this way we are able to fit the mean SED of both type I and type II AGN very well. Our fit of special objects for which high angular resolution observations (≤0.3´´) are available indicates that the hottest dust in NGC 1068 reaches the sublimation temperature while the maximum dust temperature in the low-luminosity AGN Circinus falls short of 1000 K.
Drift resonance and stability of the Io plasma torus

Science.gov (United States)

Zhan, Jie; Hill, T. W.

2000-03-01

The observed local time asymmetry of the Io plasma torus is generally attributed to the presence of a persistent dawn-to-dusk electric field in the Jovian magnetosphere. The local time asymmetry is modulated at the System 3 rotation period of Jupiter's magnetic field, suggesting that the dawn-to-dusk electric field may be similarly modulated. We argue that such a System 3 modulation would have a profound disruptive effect on the observed torus structure if the torus were to corotate at exactly the System 3 rate: the torus would be a resonantly forced harmonic oscillator, and would disintegrate in a few rotation periods, contrary to observations. This destabilizing effect is independent of, and in addition to, the more familiar effect of the centrifugal interchange instability, which is also capable of disrupting the torus in a few rotation periods in the absence of other effects. We conclude that the observed (few percent) corotation lag of the torus is essential to preserving the observed long-lived torus structure by detuning the resonant frequency (the torus drift frequency) relative to the forcing frequency (System 3). A possible outcome of this confinement mechanism is a residual radial oscillation of the torus at the beat period (~10 days) between System 3 and the torus drift period.
Torus sector handling system

International Nuclear Information System (INIS)

Grisham, D.L.

1981-01-01

A remote handling system is proposed for moving a torus sector of the accelerator from under the cryostat to a point where it can be handled by a crane and for the reverse process for a new sector. Equipment recommendations are presented, as well as possible alignment schemes. Some general comments about future remote-handling methods and the present capabilities of existing systems will also be included. The specific task to be addressed is the removal and replacement of a 425 to 450 ton torus sector. This requires a horizontal movement of approx. 10 m from a normal operating position to a point where its further transport can be accomplished by more conventional means (crane or floor transporter). The same horizontal movement is required for reinstallation, but a positional tolerance of 2 cm is required to allow reasonable fit-up for the vacuum seal from the radial frames to the torus sector. Since the sectors are not only heavy but rather tall and narrow, the transport system must provide a safe, stable, and repeatable method fo sector movement. This limited study indicates that the LAMPF-based method of transporting torus sectors offers a proven method of moving heavy items. In addition, the present state of the art in remote equipment is adequate for FED maintenance
FORMATION OF MASSIVE GALAXIES AT HIGH REDSHIFT: COLD STREAMS, CLUMPY DISKS, AND COMPACT SPHEROIDS

International Nuclear Information System (INIS)

Dekel, Avishai; Sari, Re'em; Ceverino, Daniel

2009-01-01

We present a simple theoretical framework for massive galaxies at high redshift, where the main assembly and star formation occurred, and report on the first cosmological simulations that reveal clumpy disks consistent with our analysis. The evolution is governed by the interplay between smooth and clumpy cold streams, disk instability, and bulge formation. Intense, relatively smooth streams maintain an unstable dense gas-rich disk. Instability with high turbulence and giant clumps, each a few percent of the disk mass, is self-regulated by gravitational interactions within the disk. The clumps migrate into a bulge in ∼ sun yr -1 , and each clump converts into stars in ∼0.5 Gyr. While the clumps coalesce dissipatively to a compact bulge, the star-forming disk is extended because the incoming streams keep the outer disk dense and susceptible to instability and because of angular momentum transport. Passive spheroid-dominated galaxies form when the streams are more clumpy: the external clumps merge into a massive bulge and stir up disk turbulence that stabilize the disk and suppress in situ clump and star formation. We predict a bimodality in galaxy type by z ∼ 3, involving giant-clump star-forming disks and spheroid-dominated galaxies of suppressed star formation. After z ∼ 1, the disks tend to be stabilized by the dominant stellar disks and bulges. Most of the high-z massive disks are likely to end up as today's early-type galaxies.
A new equilibrium torus solution and GRMHD initial conditions

Science.gov (United States)

Penna, Robert F.; Kulkarni, Akshay; Narayan, Ramesh

2013-11-01

Context. General relativistic magnetohydrodynamic (GRMHD) simulations are providing influential models for black hole spin measurements, gamma ray bursts, and supermassive black hole feedback. Many of these simulations use the same initial condition: a rotating torus of fluid in hydrostatic equilibrium. A persistent concern is that simulation results sometimes depend on arbitrary features of the initial torus. For example, the Bernoulli parameter (which is related to outflows), appears to be controlled by the Bernoulli parameter of the initial torus. Aims: In this paper, we give a new equilibrium torus solution and describe two applications for the future. First, it can be used as a more physical initial condition for GRMHD simulations than earlier torus solutions. Second, it can be used in conjunction with earlier torus solutions to isolate the simulation results that depend on initial conditions. Methods: We assume axisymmetry, an ideal gas equation of state, constant entropy, and ignore self-gravity. We fix an angular momentum distribution and solve the relativistic Euler equations in the Kerr metric. Results: The Bernoulli parameter, rotation rate, and geometrical thickness of the torus can be adjusted independently. Our torus tends to be more bound and have a larger radial extent than earlier torus solutions. Conclusions: While this paper was in preparation, several GRMHD simulations appeared based on our equilibrium torus. We believe it will continue to provide a more realistic starting point for future simulations.
Bifurcation structure of successive torus doubling

International Nuclear Information System (INIS)

Sekikawa, Munehisa; Inaba, Naohiko; Yoshinaga, Tetsuya; Tsubouchi, Takashi

2006-01-01

The authors discuss the 'embryology' of successive torus doubling via the bifurcation theory, and assert that the coupled map of a logistic map and a circle map has a structure capable of generating infinite number of torus doublings
Fuzzy torus via q-Parafermion

International Nuclear Information System (INIS)

Aizawa, N; Chakrabarti, R

2007-01-01

We note that the recently introduced fuzzy torus can be regarded as a q-deformed parafermion. Based on this picture, classification of the Hermitian representations of the fuzzy torus is carried out. The result involves Fock-type representations and new finite-dimensional representations for q being a root of unity as well as already known finite-dimensional ones
Spherical Torus Center Stack Design

International Nuclear Information System (INIS)

C. Neumeyer; P. Heitzenroeder; C. Kessel; M. Ono; M. Peng; J. Schmidt; R. Woolley; I. Zatz

2002-01-01

The low aspect ratio spherical torus (ST) configuration requires that the center stack design be optimized within a limited available space, using materials within their established allowables. This paper presents center stack design methods developed by the National Spherical Torus Experiment (NSTX) Project Team during the initial design of NSTX, and more recently for studies of a possible next-step ST (NSST) device
Pro-torus actions on Poincaré duality spaces

Indian Academy of Sciences (India)

duality spaces, Borel's dimension formula and topological splitting principle to local weights, hold if 'torus' is replaced by 'pro-torus'. Keywords. Pro-torus; Poincaré duality space; local weight. 1. Introduction. In the theory of linear representations of compact connected Lie groups, the crucial first step is restriction to the ...
Nuclear performance calculations for the ELMO Bumpy Torus Reactor (EBTR) reference design

International Nuclear Information System (INIS)

Santoro, R.T.; Barnes, J.M.

1977-12-01

The nuclear performance of the ELMO Bumpy Torus Reactor reference design has been calculated using the one-dimensional discrete ordinates code ANISN and the latest available ENDF/B-IV transport cross-section data and nuclear response functions. The calculated results include estimates of the spatial and integral heating rate with emphasis on the recovery of fusion neutron energy in the blanket assembly and minimization of the energy deposition rates in the cryogenic magnet coil assemblies. The tritium breeding ratio in the natural lithium-laden blanket was calculated to be 1.29 tritium nuclei per incident neutron. The radiation damage in the reactor structural material and in the magnet assembly is also given
Cold, clumpy accretion onto an active supermassive black hole.

Science.gov (United States)

Tremblay, Grant R; Oonk, J B Raymond; Combes, Françoise; Salomé, Philippe; O'Dea, Christopher P; Baum, Stefi A; Voit, G Mark; Donahue, Megan; McNamara, Brian R; Davis, Timothy A; McDonald, Michael A; Edge, Alastair C; Clarke, Tracy E; Galván-Madrid, Roberto; Bremer, Malcolm N; Edwards, Louise O V; Fabian, Andrew C; Hamer, Stephen; Li, Yuan; Maury, Anaëlle; Russell, Helen R; Quillen, Alice C; Urry, C Megan; Sanders, Jeremy S; Wise, Michael W

2016-06-09

Supermassive black holes in galaxy centres can grow by the accretion of gas, liberating energy that might regulate star formation on galaxy-wide scales. The nature of the gaseous fuel reservoirs that power black hole growth is nevertheless largely unconstrained by observations, and is instead routinely simplified as a smooth, spherical inflow of very hot gas. Recent theory and simulations instead predict that accretion can be dominated by a stochastic, clumpy distribution of very cold molecular clouds--a departure from the 'hot mode' accretion model--although unambiguous observational support for this prediction remains elusive. Here we report observations that reveal a cold, clumpy accretion flow towards a supermassive black hole fuel reservoir in the nucleus of the Abell 2597 Brightest Cluster Galaxy (BCG), a nearby (redshift z = 0.0821) giant elliptical galaxy surrounded by a dense halo of hot plasma. Under the right conditions, thermal instabilities produce a rain of cold clouds that fall towards the galaxy's centre, sustaining star formation amid a kiloparsec-scale molecular nebula that is found at its core. The observations show that these cold clouds also fuel black hole accretion, revealing 'shadows' cast by the molecular clouds as they move inward at about 300 kilometres per second towards the active supermassive black hole, which serves as a bright backlight. Corroborating evidence from prior observations of warmer atomic gas at extremely high spatial resolution, along with simple arguments based on geometry and probability, indicate that these clouds are within the innermost hundred parsecs of the black hole, and falling closer towards it.
Imaging the Obscuring Torus in Nearby Active Galaxies

Science.gov (United States)

Wilson, Andrew S.; Storchi Bergmann, Thaisa; Morris, Simon

2000-02-01

We propose to study a sample of Seyfert galaxies with the aim of resolving spatially the torus of dense molecular gas and dust which is believed to surround the nuclei of these objects. The galaxies, selected to have strong molecular hydrogen emission and jet-like radio continuum sources, will be imaged in various molecular hydrogen lines and in [Fe II] or Br (gamma). The goals are to a) confirm the existence of such tori, b) determine whether the extended molecular gas is excited thermally or through fluorescence, and c) compare with the distribution of ionized gas, which may show an ionization cone structure from polar escape of ionizing photons. The availability of IR imaging capabilities with tip-tilt and narrow-band filters, which allow imaging in the H_2(lambda) 2.122(micron) line up to a recession velocity of 6,000 km s^-1, makes the Blanco 4m telescope very well suited to this project.

Cirugía de torus mandibular

Directory of Open Access Journals (Sweden)

Manuel Ramon Osorio Castillo

2014-06-01

Full Text Available ResumenLos huesos maxilares no son ajenos a las patologías que se pueden presentar en el sistema esquelético. Algunas de esas condiciones y patologías son singulares por sus características clínicas, su distribución y prevalencia. Los torus palatinos, los torus mandibulares (TM y las exostosis de los maxilares son un claro ejemplo de ellos. Hasta la presente existen ideas especulativas acerca de su etiopatogenia, de los factores asociados, de su incidencia y prevalencia, de su necesidad de tratamiento, lo que puede crear confusión entre los clínicos tanto en diagnóstico como en el manejo.El torus como tumor óseo benigno puede localizarse en el maxilar a nivel del paladar, o en la mandíbula a nivel de las tablas internas; o puede aparecer en cualquier parte del esqueleto. El TM es una exostosis o crecimiento óseo en la superficie lingual de la mandíbula. Este crecimiento ocurre generalmente cerca de la línea milohioidea, opuesto a los premolares, pero se puede extender del canino al primer molar. La mucosa que los recubre tiende a ser fina y no tolera por lo general las fuerzas de las prótesis que se colocan encima de ellos. La incidencia del torus de la mandíbula es baja en el 6% a 12.5% entre caucásicos y en los habitantes de la llanura africana. De manera contraria, algunos autores reportan una prevalencia mucho más elevada en la Costa Atlántica Colombiana.Se presenta el caso de un paciente con torus mandibulares bilaterales, con muchos años de crecimiento, hasta que por situaciones tanto fonéticas como de ulceraciones repetitivas decidió someterse al acto quirúrgico de forma bilateral. Se presentan algunas consideraciones para el manejo de esta. (Duazary 2008; 111-114AbstractThe jawbone is not a strange to the pathologies that can occur in the skeletal system. Some of these terms and conditions are unique for their clinical features, distribution and prevalence. The torus palate, jawbone torus (TM in spanish and
Tool path in torus tool CNC machining

Directory of Open Access Journals (Sweden)

XU Ying

2016-10-01

Full Text Available This paper is about tool path in torus tool CNC machining.The mathematical model of torus tool is established.The tool path planning algorithm is determined through calculation of the cutter location,boundary discretization,calculation of adjacent tool path and so on,according to the conversion formula,the cutter contact point will be converted to the cutter location point and then these points fit a toolpath.Lastly,the path planning algorithm is implemented by using Matlab programming.The cutter location points for torus tool are calculated by Matlab,and then fit these points to a toolpath.While using UG software,another tool path of free surface is simulated of the same data.It is drew compared the two tool paths that using torus tool is more efficient.
Methanol in the L1551 Circumbinary Torus

OpenAIRE

White, Glenn J.; Fridlund, C. W. M.; Bergman, P.; Beardsmore, A.; Liseau, Rene; Phillips, R. R.

2006-01-01

We report observations of gaseous methanol in an edge-on torus surrounding the young stellar object L1551 IRS5. The peaks in the torus are separated by ~ 10,000 AU from L1551 IRS5, and contain ~ 0.03 earth masses of cold methanol. We infer that the methanol abundance increases in the outer part of the torus, probably as a result of methanol evaporation from dust grain surfaces heated by the shock luminosity associated with the shocks associated with the jets of an externally located x-ray sou...
Topological T-duality for torus bundles with monodromy

Science.gov (United States)

Baraglia, David

2015-05-01

We give a simplified definition of topological T-duality that applies to arbitrary torus bundles. The new definition does not involve Chern classes or spectral sequences, only gerbes and morphisms between them. All the familiar topological conditions for T-duals are shown to follow. We determine necessary and sufficient conditions for existence of a T-dual in the case of affine torus bundles. This is general enough to include all principal torus bundles as well as torus bundles with arbitrary monodromy representations. We show that isomorphisms in twisted cohomology, twisted K-theory and of Courant algebroids persist in this general setting. We also give an example where twisted K-theory groups can be computed by iterating T-duality.
Testing AGN unification via inference from large catalogs

Science.gov (United States)

Nikutta, Robert; Ivezic, Zeljko; Elitzur, Moshe; Nenkova, Maia

2018-01-01

Source orientation and clumpiness of the central dust are the main factors in AGN classification. Type-1 QSOs are easy to observe and large samples are available (e.g. in SDSS), but obscured type-2 AGN are dimmer and redder as our line of sight is more obscured, making it difficult to obtain a complete sample. WISE has found up to a million QSOs. With only 4 bands and a relatively small aperture the analysis of individual sources is challenging, but the large sample allows inference of bulk properties at a very significant level.CLUMPY (www.clumpy.org) is arguably the most popular database of AGN torus SEDs. We model the ensemble properties of the entire WISE AGN content using regularized linear regression, with orientation-dependent CLUMPY color-color-magnitude (CCM) tracks as basis functions. We can reproduce the observed number counts per CCM bin with percent-level accuracy, and simultaneously infer the probability distributions of all torus parameters, redshifts, additional SED components, and identify type-1/2 AGN populations through their IR properties alone. We increase the statistical power of our AGN unification tests even further, by adding other datasets as axes in the regression problem. To this end, we make use of the NOAO Data Lab (datalab.noao.edu), which hosts several high-level large datasets and provides very powerful tools for handling large data, e.g. cross-matched catalogs, fast remote queries, etc.
LASL Compact Torus Program

International Nuclear Information System (INIS)

Linford, R.K.; Armstrong, W.T.; Bartsch, R.R.

1981-01-01

The Compact Torus (CT) concept includes any axisymmetric toroidal plasma configuration, which does not require the linking of any material through the hole in the torus. Thus, the magnet coils, vacuum vessel, etc., have a simple cylindrical or spherical geometry instead of the toroidal geometry required for Tokamaks and RFP's. This simplified geometry results in substantial engineering advantages in CT reactor embodiments while retaining the good confinement properties afforded by an axisymmetric toroidal plasma-field geometry. CT's can be classified into three major types by using the ion gyro radius rho/sub i/ and the magnitude of the maximum toroidal field B/sub tm/
Partially collisional model of the Titan hydrogen torus

International Nuclear Information System (INIS)

Hilton, D.A.

1987-01-01

A numerical model was developed for atomic hydrogen densities in the Titan hydrogen torus. The effects of occasional collisions were included in order to accurately simulate physical conditions inferred from the Voyager 1 and 2 Ultraviolet Spectrometer (UVS) results of Broadfoot et al. (1981) and Sandel et al. (1982). The model employed Lagrangian perturbation of orbital elements of hydrogen atoms launched from Titan and Monte Carlo simulation of collisions and loss mechanisms. The torus is found to be azimuthally symmetric with the density sharply peaked at Titan's orbit, and decreasing rapidly in the outward and perpendicular directions and more gradually inward from 17 to 5 R/sub s/. The energetic hydrogen atoms from Saturn's upper atmosphere, first predicted by Shemansky and Smith (1982), were also investigated. Collisions of these Saturnian atoms with the torus population do not contribute to the torus density, and will lead to a net loss of torus atoms if their launch speeds from Saturn extend above 40 km/sec. The Saturnian atoms produce a corona which was modeled using the theory of Chamberlain (1963)
Multicast Performance Analysis for High-Speed Torus Networks

National Research Council Canada - National Science Library

Oral, S; George, A

2002-01-01

... for unicast-based and path-based multicast communication on high-speed torus networks. Software-based multicast performance results of selected algorithms on a 16-node Scalable Coherent Interface (SCI) torus are given...
Geometrically Thick Obscuration by Radiation-driven Outflow from Magnetized Tori of Active Galactic Nuclei

Energy Technology Data Exchange (ETDEWEB)

Chan, Chi-Ho [Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Krolik, Julian H. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)

2017-07-01

Near-Eddington radiation from active galactic nuclei (AGNs) has significant dynamical influence on the surrounding dusty gas, plausibly furnishing AGNs with geometrically thick obscuration. We investigate this paradigm with radiative magnetohydrodynamics simulations. The simulations solve the magnetohydrodynamics equations simultaneously with the infrared (IR) and ultraviolet (UV) radiative transfer (RT) equations; no approximate closure is used for RT. We find that our torus, when given a suitable sub-Keplerian angular momentum profile, spontaneously evolves toward a state in which its opening angle, density distribution, and flow pattern change only slowly. This “steady” state lasts for as long as there is gas resupply toward the inner edge. The torus is best described as a midplane inflow and a high-latitude outflow. The outflow is launched from the torus inner edge by UV radiation and expands in solid angle as it ascends; IR radiation continues to drive the wide-angle outflow outside the central hole. The dusty outflow obscures the central source in soft X-rays, the IR, and the UV over three-quarters of solid angle, and each decade in column density covers roughly equal solid angle around the central source; these obscuration properties are similar to what observations imply.
Effect of robust torus on the dynamical transport

International Nuclear Information System (INIS)

Martins, C G L; Carvalho, R Egydio de; Caldas, I L; Roberto, M

2010-01-01

In the present work, we quantify the fraction of trajectories that reach a specific region of the phase space when we vary a control parameter using two symplectic maps: one non-twist and another one twist. The two maps were studied with and without a robust torus. We compare the obtained patterns and we identify the effect of the robust torus on the dynamical transport. We show that the effect of meandering-like barriers loses importance in blocking the radial transport when the robust torus is present.
Magnetic translation groups in an n-dimensional torus and their representations

International Nuclear Information System (INIS)

Tanimura, Shogo

2002-01-01

A charged particle in a uniform magnetic field in a two-dimensional torus has a discrete noncommutative translation symmetry instead of a continuous commutative translation symmetry. We study topology and symmetry of a particle in a magnetic field in a torus of arbitrary dimensions. The magnetic translation group (MTG) is defined as a group of translations that leave the gauge field invariant. We show that the MTG in an n-dimensional torus is isomorphic to a central extension of a cyclic group Z ν 1 x···xZ ν 2l xT m by U(1) with 2l+m=n. We construct and classify irreducible unitary representations of the MTG in a three-torus and apply the representation theory to three examples. We briefly describe a representation theory for a general n-torus. The MTG in an n-torus can be regarded as a generalization of the so-called noncommutative torus
X-RAY ABSORPTION, NUCLEAR INFRARED EMISSION, AND DUST COVERING FACTORS OF AGNs: TESTING UNIFICATION SCHEMES

Energy Technology Data Exchange (ETDEWEB)

Mateos, S.; Carrera, F. J.; Alonso-Herrero, A.; Hernán-Caballero, A.; Barcons, X. [Instituto de Física de Cantabria (CSIC-Universidad de Cantabria), E-39005, Santander (Spain); Ramos, A. Asensio; Almeida, C. Ramos [Instituto de Astrofísica de Canarias, E-38205, La Laguna, Tenerife (Spain); Watson, M. G.; Blain, A. [Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Caccianiga, A.; Ballo, L. [INAF-Osservatorio Astronomico di Brera, via Brera 28, I-20121 Milano (Italy); Braito, V., E-mail: mateos@ifca.unican.es [INAF-Osservatorio Astronomico di Brera, Via Bianchi 46, I-23807 Merate (Italy)

2016-03-10

We present the distributions of the geometrical covering factors of the dusty tori (f{sub 2}) of active galactic nuclei (AGNs) using an X-ray selected complete sample of 227 AGNs drawn from the Bright Ultra-hard XMM-Newton Survey. The AGNs have z from 0.05 to 1.7, 2–10 keV luminosities between 10{sup 42} and 10{sup 46} erg s{sup −1}, and Compton-thin X-ray absorption. Employing data from UKIDSS, 2MASS, and the Wide-field Infrared Survey Explorer in a previous work, we determined the rest-frame 1–20 μm continuum emission from the torus, which we model here with the clumpy torus models of Nenkova et al. Optically classified type 1 and type 2 AGNs are intrinsically different, with type 2 AGNs having, on average, tori with higher f{sub 2} than type 1 AGNs. Nevertheless, ∼20% of type 1 AGNs have tori with large covering factors, while ∼23%–28% of type 2 AGNs have tori with small covering factors. Low f{sub 2} are preferred at high AGN luminosities, as postulated by simple receding torus models, although for type 2 AGNs the effect is certainly small. f{sub 2} increases with the X-ray column density, which implies that dust extinction and X-ray absorption take place in material that share an overall geometry and most likely belong to the same structure, the putative torus. Based on our results, the viewing angle, AGN luminosity, and also f{sub 2} determine the optical appearance of an AGN and control the shape of the rest-frame ∼1–20 μm nuclear continuum emission. Thus, the torus geometrical covering factor is a key ingredient of unification schemes.
TORUS: Theory of Reactions for Unstable iSotopes - Year 1 Continuation and Progress Report

Energy Technology Data Exchange (ETDEWEB)

Arbanas, G; Elster, C; Escher, J; Mukhamedzhanov, A; Nunes, F; Thompson, I J

2011-02-24

The TORUS collaboration derives its name from the research it focuses on, namely the Theory of Reactions for Unstable iSotopes. It is a Topical Collaboration in Nuclear Theory, and funded by the Nuclear Theory Division of the Office of Nuclear Physics in the Office of Science of the Department of Energy. The funding started on June 1, 2010, it will have been running for nine months by the date of submission of this Annual Continuation and Progress Report on March 1, 2011. The extent of funding was reduced from the original application, and now supports one postdoctoral researcher for the years 1 through 3. The collaboration brings together as Principal Investigators a large fraction of the nuclear reaction theorists currently active within the USA. The mission of the TORUS Topical Collaboration is to develop new methods that will advance nuclear reaction theory for unstable isotopes by using three-body techniques to improve direct-reaction calculations, and, by using a new partial-fusion theory, to integrate descriptions of direct and compound-nucleus reactions. This multi-institution collaborative effort is directly relevant to three areas of interest: the properties of nuclei far from stability; microscopic studies of nuclear input parameters for astrophysics, and microscopic nuclear reaction theory.
Torus actions and their applications in topology and combinatorics

CERN Document Server

Buchstaber, Victor M

2002-01-01

The book presents the study of torus actions on topological spaces is presented as a bridge connecting combinatorial and convex geometry with commutative and homological algebra, algebraic geometry, and topology. This established link helps in understanding the geometry and topology of a space with torus action by studying the combinatorics of the space of orbits. Conversely, subtle properties of a combinatorial object can be realized by interpreting it as the orbit structure for a proper manifold or as a complex acted on by a torus. The latter can be a symplectic manifold with Hamiltonian torus action, a toric variety or manifold, a subspace arrangement complement, etc., while the combinatorial objects include simplicial and cubical complexes, polytopes, and arrangements. This approach also provides a natural topological interpretation in terms of torus actions of many constructions from commutative and homological algebra used in combinatorics. The exposition centers around the theory of moment-angle comple...
Torus bifurcations in multilevel converter systems

DEFF Research Database (Denmark)

Zhusubaliyev, Zhanybai T.; Mosekilde, Erik; Yanochkina, Olga O.

2011-01-01

embedded one into the other and with their basins of attraction delineated by intervening repelling tori. The paper illustrates the coexistence of three stable tori with different resonance behaviors and shows how reconstruction of these tori takes place across the borders of different dynamical regimes....... The paper also demonstrates how pairs of attracting and repelling tori emerge through border-collision torus-birth and border-collision torus-fold bifurcations. © 2011 World Scientific Publishing Company....
Induction effects of torus knots and unknots

Science.gov (United States)

Oberti, Chiara; Ricca, Renzo L.

2017-09-01

Geometric and topological aspects associated with induction effects of field lines in the shape of torus knots/unknots are examined and discussed in detail. Knots are assumed to lie on a mathematical torus of circular cross-section and are parametrized by standard equations. The induced field is computed by direct integration of the Biot-Savart law. Field line patterns of the induced field are obtained and several properties are examined for a large family of knots/unknots up to 51 crossings. The intensity of the induced field at the origin of the reference system (center of the torus) is found to depend linearly on the number of toroidal coils and reaches maximum values near the boundary of the mathematical torus. New analytical estimates and bounds on energy and helicity are established in terms of winding number and minimum crossing number. These results find useful applications in several contexts when the source field is either vorticity, electric current or magnetic field, from vortex dynamics to astrophysics and plasma physics, where highly braided magnetic fields and currents are present.
Dynamics and Formation of Obscuring Tori in AGNs

Energy Technology Data Exchange (ETDEWEB)

Bannikova, Elena Yu.; Sergeyev, Alexey V., E-mail: bannikova@astron.kharkov.ua [Institute of Radio Astronomy, National Academy of Science of Ukraine, Kharkiv (Ukraine); Institute of Astronomy, V. N. Karazin Kharkiv National University, Kharkiv (Ukraine)

2017-12-12

We considered the evolution of a self-gravitating clumpy torus in the gravitational field of the central mass of an active galactic nucleus (AGN) in the framework of the N-body problem. The initial conditions take into account winds with different opening angles. Results of our N-body simulations show that the clouds moving on orbits with a spread in inclinations and eccentricities form a toroidal region. The velocity of the clouds at the inner boundary of the torus is lower than in a disk model that can explain the observed rotation curves. We discuss the scenario of torus formation related with the beginning of the AGN stage.
TORUS: Theory of Reactions for Unstable iSotopes Annual Continuation and Progress Report Year-2: March 1, 2011 - February 29, 2012

Energy Technology Data Exchange (ETDEWEB)

Arbanas, G; Elster, C; Escher, J; Mukhamedzanov, A; Nunes, F; Thompson, I J

2012-02-24

The TORUS collaboration derives its name from the research it focuses on, namely the Theory of Reactions for Unstable iSotopes. It is a Topical Collaboration in Nuclear Theory, and funded by the Nuclear Theory Division of the Office of Nuclear Physics in the Office of Science of the Department of Energy. The funding supports one postdoctoral researcher for the years 1 through 3. The collaboration brings together as Principal Investigators a large fraction of the nuclear reaction theorists currently active within the USA. The mission of the TORUS Topical Collaboration is to develop new methods that will advance nuclear reaction theory for unstable isotopes by using three-body techniques to improve direct-reaction calculations, and, by using a new partial-fusion theory, to integrate descriptions of direct and compound-nucleus reactions. This multi-institution collaborative effort is directly relevant to three areas of interest: the properties of nuclei far from stability; microscopic studies of nuclear input parameters for astrophysics, and microscopic nuclear reaction theory.
Studying uniform thickness II: Transversely nonsimple iterated torus knots

DEFF Research Database (Denmark)

LaFountain, Douglas

2011-01-01

We prove that an iterated torus knot type in the standard contact 3-sphere fails the uniform thickness property (UTP) if and only if it is formed from repeated positive cablings, which is precisely when an iterated torus knot supports the standard contact structure. This is the first complete UTP...... classification for a large class of knots. We also show that all iterated torus knots that fail the UTP support cabling knot types that are transversely non-simple....
Spherical torus, compact fusion at low field

International Nuclear Information System (INIS)

Peng, Y.K.M.

1985-02-01

A spherical torus is obtained by retaining only the indispensable components on the inboard side of a tokamak plasma, such as a cooled, normal conductor that carries current to produce a toroidal magnetic field. The resulting device features an exceptionally small aspect ratio (ranging from below 2 to about 1.3), a naturally elongated D-shaped plasma cross section, and ramp-up of the plasma current primarily by noninductive means. As a result of the favorable dependence of the tokamak plasma behavior to decreasing aspect ratio, a spherical torus is projected to have small size, high beta, and modest field. Assuming Mirnov confinement scaling, an ignition spherical torus at a field of 2 T features a major radius of 1.5 m, a minor radius of 1.0 m, a plasma current of 14 MA, comparable toroidal and poloidal field coil currents, an average beta of 24%, and a fusion power of 50 MW. At 2 T, a Q = 1 spherical torus will have a major radius of 0.8 m, a minor radius of 0.5 m, and a fusion power of a few megawatts

Toroidal Superheavy Nuclei in Skyrme-Hartree-Fock Approach

International Nuclear Information System (INIS)

Staszczak, A.; Wong, Cheuk-Yin

2009-01-01

Within the self-consistent constraint Skyrme-Hartree-Fock+BCS model (SHF+BCS), we found equilibrium toroidal nuclear density distributions in the region of superheavy elements. For nuclei with a sufficient oblate deformation (Q 20 < -200 b), it becomes energetically favorable to change the genus of nuclear surface from 0 to 1, i.e., to switch the shape from a biconcave disc to a torus. The energy of the toroidal (genus=1) SHF+BCS solution relative to the compact (genus=0) ground state energy is strongly dependent both on the atomic number Z and the mass number A. We discuss the region of Z and A where the toroidal SHF+BCS total energy begins to be a global minimum
Quasiperiodicity and Torus Breakdown in a Power Electronic DC/DC Converter

DEFF Research Database (Denmark)

Zhusubaliyev, Zhanybai; Soukhoterin, Evgeniy; Mosekilde, Erik

2007-01-01

This paper discusses the mechanisms of torus formation and torus destruction in a dc/dc converter with relay control and hysteresis. We establish a chart of the dynamical modes in the input voltage versus load resistance parameter plane. This chart displays several different torus bifurcations...
Current drive experiments on the HIT-II spherical torus

International Nuclear Information System (INIS)

Jarboe, T.R.; Raman, R.; Nelson, B.A.; Holcomb, C.T.; McCollam, K.J.; Sieck, P.E.

1999-01-01

This paper describes the following new achievements from the Helicity Injected Torus (HIT) program: a) formation and sustainment of a toroidal magnetic equilibrium using coaxial helicity injection (CHI) in a conducting shell that has an L/R time much shorter than the pulse length; b) static formation of a spherical torus with plasma current over 180 kA using a transformer and feedback controlled equilibrium coils; and c) production of a current increase in a transformer produced spherical torus using CHI. (author)
Current drive experiments on the HIT-II spherical torus

International Nuclear Information System (INIS)

Jarboe, T.; Raman, R.; Nelson, B.; Holcomb, C.T.; McCollam, K.J.; Sieck, P.E.

2001-01-01

This paper describes the following new achievements from the Helicity Injected Torus (HIT) program: a) formation and sustainment of a toroidal magnetic equilibrium using coaxial helicity injection (CHI) in a conducting shell that has an L/R time much shorter than the pulse length; b) static formation of a spherical torus with plasma current over 180 kA using a transformer and feedback controlled equilibrium coils; and c) production of a current increase in a transformer produced spherical torus using CHI. (author)
FLIT: Flowing LIquid metal Torus

Science.gov (United States)

Kolemen, Egemen; Majeski, Richard; Maingi, Rajesh; Hvasta, Michael

2017-10-01

The design and construction of FLIT, Flowing LIquid Torus, at PPPL is presented. FLIT focuses on a liquid metal divertor system suitable for implementation and testing in present-day fusion systems, such as NSTX-U. It is designed as a proof-of-concept fast-flowing liquid metal divertor that can handle heat flux of 10 MW/m2 without an additional cooling system. The 72 cm wide by 107 cm tall torus system consisting of 12 rectangular coils that give 1 Tesla magnetic field in the center and it can operate for greater than 10 seconds at this field. Initially, 30 gallons Galinstan (Ga-In-Sn) will be recirculated using 6 jxB pumps and flow velocities of up to 10 m/s will be achieved on the fully annular divertor plate. FLIT is designed as a flexible machine that will allow experimental testing of various liquid metal injection techniques, study of flow instabilities, and their control in order to prove the feasibility of liquid metal divertor concept for fusion reactors. FLIT: Flowing LIquid metal Torus. This work is supported by the US DOE Contract No. DE-AC02-09CH11466.
Reactor assessments of advanced bumpy torus configurations

International Nuclear Information System (INIS)

Uckan, N.A.; Owen, L.W.; Spong, D.A.; Miller, R.L.; Ard, W.B.; Pipkins, J.F.; Schmitt, R.J.

1984-02-01

Recently, several innovative approaches were introduced for enhancing the performance of the basic ELMO Bumpy Torus (EBT) concept and for improving its reactor potential. These include planar racetrack and square geometries, Andreoletti coil systems, and bumpy torus-stellarator hybrids (which include twisted racetrack and helical axis stellarator - snakey torus). Preliminary evaluations of reactor implications of each approach have been carried out based on magnetics (vacuum) calculations, transport and scaling relationships, and stability properties deduced from provisional configurations that implement the approach but are not necessarily optimized. Further optimization is needed in all cases to evaluate the full potential of each approach. Results of these studies indicate favorable reactor projections with a significant reduction in reactor physical size as compared to conventional EBT reactor designs carried out in the past
Canopy clumpiness and radiation penetration in a young hedgerow apple orchard

International Nuclear Information System (INIS)

Cohen, S.; Mosoni, P.; Meron, M.

1995-01-01

Model inversion procedures for computing leaf area index (LAI) from radiation measurements depend on foliage organization in space. The objective of this study is to find the parameters quantifying the geometry of a 5-year-old hedgerow apple orchard and to test the assumptions in the radiation penetration model serving to derive LAI. Leaves within contour intervals of photosynthetic photon flux density (PPFD) were picked and their area determined. Calculated extinction coefficients for these intervals were positively correlated with LAI. Clumpiness factors (i.e. independent leaf area layer thicknesses for the negative; binomial model) δ, for these contour intervals, showed that the canopy is very clumpy on the outside (7 < δ < 15 for average-sized ‘normal’ trees, and 3 < δ < 7 for smaller than average ‘weak’ trees) and close to random on the inside (2 < δ < 4 for normal trees and 1 < δ < 3 for weak trees). Cluster analysis theory shows that leaves in the upper part of the tree were clustered around leafy shoots whereas lower in the canopy clustering around shoots weakened. A model of gap frequency in a stand of vertical columns of leaves was used to evaluate gap frequency in a tree composed of long leafy shoots. Assuming that the density of the vertical columns. is proportional to the cumulative LAI traversed by a ray predicts a light penetration profile similar to that measured in the apple trees. The results imply that measurement of LAI of the upper part of the canopy with inversion techniques may result in severe underestimations. Similarly, radiation penetration in this part of the canopy is underestimated by simple turbid medium models. (author)
On some Closed Magnetic Curves on a 3-torus

Energy Technology Data Exchange (ETDEWEB)

Munteanu, Marian Ioan, E-mail: marian.ioan.munteanu@gmail.com [Alexandru Ioan Cuza University of Iaşi, Faculty of Mathematics (Romania); Nistor, Ana Irina, E-mail: ana.irina.nistor@gmail.com [Gh. Asachi Technical University of Iaşi, Department of Mathematics and Informatics (Romania)

2017-06-15

We consider two magnetic fields on the 3-torus obtained from two different contact forms on the Euclidean 3-space and we study when their corresponding normal magnetic curves are closed. We obtain periodicity conditions analogues to those for the closed geodesics on the torus.
Torus type thermonuclear device

International Nuclear Information System (INIS)

Gomei, Yoshio.

1982-01-01

Purpose: To facilitate heat removal at limiters and enable helium discharge without using a diverter by the separate disposition of a main limiter receiving the heat from plasmas and an auxiliary limiter for helium discharge. Constitution: A main limiter for establishing and maintaining torus plasmas and an auxiliary limiter for helium discharge are disposed separately. The auxiliary limiter is disposed between the magnetic plane at the position where the plasmas in the confining region begin to contact the main limiter and the first blanket wall. Thus, a sufficient contact area with the plasmas can be taken for the main limiter disposed to the inside of the torus to thereby avoid excess heat concentration. Further, helium ions transported through a passage along the magnetic plane between the main limiter and the first blanket wall to the exhaust chamber are neutralized and thereafter discharged by the auxiliary limiter. (Moriyama, K.)
Principal noncommutative torus bundles

DEFF Research Database (Denmark)

Echterhoff, Siegfried; Nest, Ryszard; Oyono-Oyono, Herve

2008-01-01

of bivariant K-theory (denoted RKK-theory) due to Kasparov. Using earlier results of Echterhoff and Williams, we shall give a complete classification of principal non-commutative torus bundles up to equivariant Morita equivalence. We then study these bundles as topological fibrations (forgetting the group...
Linear pinch driven by a moving compact torus

International Nuclear Information System (INIS)

Hartman, C.W.; Hammer, J.H.; Eddleman, J.L.

1984-01-01

In principle, a Z-pinch of sufficiently large aspect ratio can provide arbitrarily high magnetic field intensity for the confinement of plasma. In practice, however, achievable field intensities and timescales are limited by parasitic inductances, pulse driver power, current, voltage, and voltage standoff of nearby insulating surfaces or surrounding gas. Further, instabilities may dominate to prevent high fields (kink mode) or enhance them (sausage mode) but in a nonuniform and uncontrollable way. In this paper we discuss an approach to producing a high-field-intensity pinch using a moving compact torus. The moving torus can serve as a very high power driver and may be used to compress a pre-established pinch field, switch on an accelerating pinch field, or may itself be reconfigured to form an intense pinch. In any case, the high energy, high energy density, and high velocity possible with an accelerated compact torus can provide extremely high power to overcome, by a number of orders of magnitude, the limitations to pinch formation described earlier. In this paper we will consider in detail pinches formed by reconfiguration of the compact torus
Fabrication of an alumina torus for thermonuclear fusion containment

International Nuclear Information System (INIS)

Hauth, W.E.; Blake, R.D.; Dickinson, J.M.; Rutz, H.L.; Stoddard, S.D.

1978-05-01

A 235-cm-diam torus has been fabricated for plasma containment during thermonuclear fusion experiments. This 30-cm-diam torus consists of sixty 99.5%-alumina segments, 80% of which are assembled by forming vacuum-tight ceramic-to-ceramic seals. Selection of sealing materials and techniques are discussed
Diagnosing the Kinematics of the Tori in Active Galactic Nuclei with the Velocity-resolved Reverberation Mapping of the Narrow Iron K α Line

Energy Technology Data Exchange (ETDEWEB)

Liu Yuan; Li Xiaobo, E-mail: liuyuan@ihep.ac.cn, E-mail: lixb@ihep.ac.cn [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918-3, Beijing 100049 (China)

2017-07-20

The properties of the dusty tori in active galactic nuclei (AGNs) have been investigated in detail, mainly focusing on the geometry and components; however, the kinematics of the torus are still not clear. The narrow iron K α line at 6.4 keV is thought to be produced by the X-ray reflection from the torus. Thus, the velocity-resolved reverberation mapping of it is able to constrain the kinematics of the torus. Such effort is limited by the spectral resolution of current charged coupled device (CCD) detectors and should be possible with the microcalorimeter on the next generation X-ray satellite. In this paper, we first construct the response functions of the torus under a uniform inflow, a Keplerian rotation, and a uniform outflow. Then the energy-dependent light curve of the narrow iron K α line is simulated according to the performance of the X-ray Integral Field Unit in Athena. Finally, the energy-dependent cross-correlation function is calculated to reveal the kinematic signal. According to our results, 100 observations with 5 ks exposure of each are sufficient to distinguish the above three velocity fields. Although the real geometry and velocity field of the torus could be more complex than we assumed, the present result proves the feasibility of the velocity-resolved reverberation mapping of the narrow iron K α line. The combination of the dynamics of the torus with those of the broad-line region and the host galaxy is instructive for the understanding of the feeding and feedback process of AGNs.
DUST IN ACTIVE GALACTIC NUCLEI: ANOMALOUS SILICATE TO OPTICAL EXTINCTION RATIOS?

Energy Technology Data Exchange (ETDEWEB)

Lyu, Jianwei; Hao, Lei [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Li, Aigen, E-mail: haol@shao.ac.cn [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States)

2014-09-01

Dust plays a central role in the unification theory of active galactic nuclei (AGNs). However, little is known about the nature (e.g., size, composition) of the dust that forms a torus around the AGN. In this Letter, we report a systematic exploration of the optical extinction (A{sub V} ) and the silicate absorption optical depth (Δτ{sub 9.7}) of 110 type 2 AGNs. We derive A{sub V} from the Balmer decrement based on the Sloan Digital Sky Survey data, and Δτ{sub 9.7} from the Spitzer/InfraRed Spectrograph data. We find that with a mean ratio of (A{sub V} /Δτ{sub 9.7}) ≲ 5.5, the optical-to-silicate extinction ratios of these AGNs are substantially lower than that of the Galactic diffuse interstellar medium (ISM) for which A{sub V} /Δτ{sub 9.7} ≈ 18.5. We argue that the anomalously low A{sub V} /Δτ{sub 9.7} ratio could be due to the predominance of larger grains in the AGN torus compared to that in the Galactic diffuse ISM.
Surgical management of palatine Torus - case series

Directory of Open Access Journals (Sweden)

Thaís Sumie Nozu Imada

Full Text Available INTRODUCTION: Torus palatinus is a specific name to identify exostoses developed in the hard palate along the median palatine suture. Despite of not being a pathological condition, its presence requires attention and knowledge regarding its management. Surgical removal of exostoses is indicated when the patient frequently traumatizes the area of palatine torus during mastication and speech or when it is necessary for the rehabilitation of the upper arcade with complete dentures. OBJECTIVE: The aim of this article is to present three cases of Torus palatinus and to discuss the management of them. CASE REPORT: In the first case, a 57-year-old Caucasian man sought oral rehabilitation of his edentulous maxilla but presented a hard nodules in the hard palate; in the second case, a 40-year-old Caucasian woman was referred for frequent trauma of palatal mucosa during mastication, aesthetic complaint, and discomfort caused by the trauma of her tongue in this area; and in the third case, a 45-year-old Caucasian woman presented with a lesion on the palate that caused difficulty swallowing. When the Torus palatinus was impairing the basic physiological functions of the patients, all cases were surgically treated, improving the patients' quality of life. FINAL CONSIDERATION: The dentist should be properly prepared to choose the best from among the existing surgical approaches for each individual lesion in order to improve the results and avoid possible complications.
Next Step Spherical Torus Design Studies

International Nuclear Information System (INIS)

Neumeyer, C.; Heitzenroeder, P.; Kessel, C.; Ono, M.; Peng, M.; Schmidt, J.; Woolley, R.; Zatz, I.

2002-01-01

Studies are underway to identify and characterize a design point for a Next Step Spherical Torus (NSST) experiment. This would be a ''Proof of Performance'' device which would follow and build upon the successes of the National Spherical Torus Experiment (NSTX) a ''Proof of Principle'' device which has operated at PPPL since 1999. With the Decontamination and Decommissioning (DandD) of the Tokamak Fusion Test Reactor (TFTR) nearly completed, the TFTR test cell and facility will soon be available for a device such as NSST. By utilizing the TFTR test cell, NSST can be constructed for a relatively low cost on a short time scale. In addition, while furthering spherical torus (ST) research, this device could achieve modest fusion power gain for short-pulse lengths, a significant step toward future large burning plasma devices now under discussion in the fusion community. The selected design point is Q=2 at HH=1.4, P subscript ''fusion''=60 MW, 5 second pulse, with R subscript ''0''=1.5 m, A=1.6, I subscript ''p''=10vMA, B subscript ''t''=2.6 T, CS flux=16 weber. Most of the research would be conducted in D-D, with a limited D-T campaign during the last years of the program
Various semiclassical limits of torus conformal blocks

Energy Technology Data Exchange (ETDEWEB)

Alkalaev, Konstantin [I.E. Tamm Department of Theoretical Physics, P.N. Lebedev Physical Institute,Leninsky ave. 53, Moscow, 119991 (Russian Federation); Department of General and Applied Physics, Moscow Institute of Physics and Technology,Institutskiy per. 7, Dolgoprudnyi, Moscow region, 141700 (Russian Federation); Geiko, Roman [Mathematics Department, National Research University Higher School of Economics,Usacheva str. 6, Moscow, 119048 (Russian Federation); Rappoport, Vladimir [I.E. Tamm Department of Theoretical Physics, P.N. Lebedev Physical Institute,Leninsky ave. 53, Moscow, 119991 (Russian Federation); Department of Quantum Physics, Institute for Information Transmission Problems,Bolshoy Karetny per. 19, Moscow, 127994 (Russian Federation)

2017-04-12

We study four types of one-point torus blocks arising in the large central charge regime. There are the global block, the light block, the heavy-light block, and the linearized classical block, according to different regimes of conformal dimensions. It is shown that the blocks are not independent being connected to each other by various links. We find that the global, light, and heavy-light blocks correspond to three different contractions of the Virasoro algebra. Also, we formulate the c-recursive representation of the one-point torus blocks which is relevant in the semiclassical approximation.
Design innovations of the next-step spherical torus experiment and spherical torus development path

International Nuclear Information System (INIS)

Ono, M.; Kessel, C.; Peng, M.

2003-01-01

The spherical torus (ST) fusion energy development path is complementary to the tokamak burning plasma experiment such as ITER as it focuses toward the compact Component Test Facility (CTF) and higher toroidal beta regimes to improve the design of DEMO and a Power Plant. To support the ST development path, one option of a Next Step Spherical Torus (NSST) device is examined. NSST is a 'performance extension' (PE) stage ST with a plasma current of 5 - 10 MA, R = 1.5, B T ≤ 2.7 T with flexible physics capability to 1) Provide a sufficient physics basis for the design of the CTF, 2) Explore advanced operating scenarios with high bootstrap current fraction/high performance regimes, which can then be utilized by CTF, DEMO, and Power Plants, 3) Contribute to the general plasma/fusion science of high β toroidal plasmas. The NSST facility is designed to utilize the TFTR site to minimize the cost and time required for the construction. (author)
The Columbia Non-neutral Torus

International Nuclear Information System (INIS)

Pedersen, Thomas Sunn

2009-01-01

Final report for the Columbia Non-neutral Torus. This details the results from the design, construction and initial operation of the Columbia Non-neutral Torus. During the duration of this grant, I designed, built, and operated the Columbia Nonneutral Torus, the world's lowest aspect ratio stellarator, and arguably, the world's simplest stellarator. This demonstrates the ease and robustness of the chosen stellarator design and allowed us to commence the investigation of the physics of non-neutral plasmas confined on magnetic surfaces. These plasmas are unique in many ways and had not previously been studied in a stellarator. Our first results showed that it is possible to confine and study a relatively cold pure electron plasma in a stellarator. We confirmed that the plasma is stable, and that the plasma is reasonably well confined in a stellarator configuration. These results were published in Physics of Plasmas (2006) and Physical Review Letters (2006). They enabled the existing program which is resolving the underlying transport processes in a classical stellarator with intense self-electric fields and enable the next phase of operation, electron-positron plasma physics. During the period of this grant, two students were trained in experimental plasma physics and both received their PhD degrees shortly after the grant terminated. One student is now employed in the financial services industry, the other is a postdoctoral associate at Los Alamos National Laboratory. The chief goals were to build and begin operation of the Columbia Non-neutral Torus. These goals were achieved in the third year of funding. The development of diagnostic methods and the confirmation of stable equilibria were also achieved during the grant period. In summary, the main scientific goals were all met. The main educational goals were also met, as the experiment became the training ground not only for the two aforementioned graduate students but also for a number of undergraduate students
On the energy crisis in the Io plasma torus

Science.gov (United States)

Smith, Robert A.; Bagenal, Fran; Cheng, Andrew F.; Strobel, Darrell

1988-01-01

Recent calculations of the energy balance of the Io plasma torus show that the observed UV and EUV radiation cannot be maintained solely via energy input by the ion pickup mechanism. Current theoretical models of the torus must be modified to include non-local energy input. It is argued that the required energy may be supplied by inward diffusion of energetic heavy ions with energies less than about 20 keV.

Long Term Monitoring of the Io Plasma Torus During the Galileo Encounter

Science.gov (United States)

Brown, Michael E.

2002-01-01

In the fall of 1999, the Galileo spacecraft made four passes into the Io plasma torus, obtaining the best in situ measurements ever of the particle and field environment in this densest region of the Jovian magnetosphere. Supporting observations from the ground are vital for understanding the global and temporal context of the in situ observations. We conducted a three-month-long Io plasma torus monitoring campaign centered on the time of the Galileo plasma torus passes to support this aspect of the Galileo mission. The almost-daily plasma density and temperature measurements obtained from our campaign allow the much more sparse but also much more detailed Galileo data to be used to address the issues of the structure of the Io plasma torus, the stability mechanism of the Jovian magnetosphere, the transport of material from the source region near Io, and the nature and source of persistent longitudinal variations. Combining the ground-based monitoring data with the detailed in situ data offers the only possibility for answering some of the most fundamental questions about the nature of the Io plasma torus.
Computation of Quantum Bound States on a Singly Punctured Two-Torus

International Nuclear Information System (INIS)

Kar-Tim Chan; Zainuddin Hishamuddin; Molladavoudi Saeid

2013-01-01

We study a quantum mechanical system on a singly punctured two-torus with bound states described by the Maass waveforms which are eigenfunctions of the hyperbolic Laplace—Beltrami operator. Since the discrete eigenvalues of the Maass cusp form are not known analytically, they are solved numerically using an adapted algorithm of Hejhal and Then to compute Maass cusp forms on the punctured two-torus. We report on the computational results of the lower lying eigenvalues for the punctured two-torus and find that they are doubly-degenerate. We also visualize the eigenstates of selected eigenvalues using GridMathematica
Maass Cusp Forms on Singly Punctured Two-Torus

International Nuclear Information System (INIS)

Siddig, Abubaker Ahmed Mohamed; Shah, Nurisya Mohd; Zainuddin, Hishamuddin

2009-01-01

Quantum mechanical systems on punctured surfaces modeled by hyperbolic spaces can play an interesting role in exploring quantum chaos and in studying behaviour of future quantum nano-devices. The case of singly-punctured two-torus, for example, has been well-studied in the literature particularly for its scattering states. However, the bound states on the punctured torus given by Maass cusp forms are lesser known. In this note, we report on the algorithm of numerically computing these functions and we present ten lower-lying eigenvalues for each odd and even Maass cusp forms.
Effect of torus wall flexibility on hydro-structural interaction in BWR containment system

International Nuclear Information System (INIS)

Lu, S.C.H.; McCauley, E.W.; Holman, G.S.

1979-01-01

The MARK I boiling water reactor (BWR) containment system is comprised of a light-bulb-shaped reactor compartment connected through vent pipes to a torus-shaped and partially water-filled pressure suppression chamber, or the wetwell. During either a normally occurring safety relief valve (SRV) discharge or a hypothetical loss-of-coolant accident (LOCA), air or steam is forced into the wetwell water pool for condensation and results in hydrodynamically induced loads on the torus shell. An analytical program is described which employs the finite element method to investigate the influence of torus wall flexibility on hydrodynamically induced pressure and the resultant force on the torus shell surface. The shell flexibility is characterized by the diameter-to-thickness ratio which is varied from the perfectly rigid case to the nominal plant condition. The general conclusion reached is that torus wall flexibility decreases both the maximum pressure seen by the shell wall and the total vertical load resulted from the hydrodynamically induced pressure
Submillimeter and far infrared line observations of M17 SW: A clumpy molecular cloud penetrated by UV radiation

Science.gov (United States)

Stutzki, J.; Stacey, G. J.; Genzel, R.; Harris, A. I.; Jaffe, d. T.; Lugten, J. B.

1987-01-01

Millimeter, submillimeter, and far infrared spectroscopic observations of the M17 SW star formation region are discussed. The results require the molecular cloud near the interface to be clumpy or filamentary. As a consequence, far ultraviolet radiation from the central OB stellar cluster can penetrate into the dense molecular cloud to a depth of several pc, thus creating bright and extended (CII) emission from the photodissociated surfaces of dense atomic and molecular clumps or sheets. The extended (CII) emission throughout the molecular cloud SW of the M17 complex has a level 20 times higher than expected from a single molecular cloud interface exposed to an ultraviolet radiation field typical of the solar neighborhood. This suggests that the molecular cloud as a whole is penetrated by ultraviolet radiation and has a clumpy or filamentary structure. The number of B stars expected to be embedded in the M17 molecular cloud probably can provide the UV radiation necessary for the extended (CII) emission. Alternatively, the UV radiation could be external, if the interstellar radiation in the vicinity of M17 is higher than in the solar neighborhood.
Exploring Torus Universes in Causal Dynamical Triangulations

DEFF Research Database (Denmark)

Budd, Timothy George; Loll, R.

2013-01-01

Motivated by the search for new observables in nonperturbative quantum gravity, we consider Causal Dynamical Triangulations (CDT) in 2+1 dimensions with the spatial topology of a torus. This system is of particular interest, because one can study not only the global scale factor, but also global...... shape variables in the presence of arbitrary quantum fluctuations of the geometry. Our initial investigation focusses on the dynamics of the scale factor and uncovers a qualitatively new behaviour, which leads us to investigate a novel type of boundary conditions for the path integral. Comparing large....... Apart from setting the stage for the analysis of shape dynamics on the torus, the new set-up highlights the role of nontrivial boundaries and topology....
A major modification of the Joint European Torus using teleoperational techniques

International Nuclear Information System (INIS)

Rolfe, A.

1998-04-01

The Joint European Torus (JET) project was set up under the auspices of EURATOM in the late 1970's in order to study the feasibility of controlled Nuclear Fusion. The experimental device comprises a toroidal shaped vacuum vessel in which high temperature plasma is created and controlled. The inside of the torus is now inaccessible to personnel for around one year due to slightly elevated radiation levels. The JET programme however requires the immediate replacement of a major system within the torus and this must therefore be achieved using only remote handling techniques. This paper describes the preparations for this first fully remote handling shutdown at JET. (author)
Infrared emission in Seyfert 2 galaxies - Reprocessed radiation from a dusty torus?

Science.gov (United States)

Storchi-Bergmann, Thaisa; Mulchaey, John S.; Wilson, Andrew S.

1992-01-01

New and existing data for a sample of nine Seyfert 2 galaxies with known 'ionization cones' are combined in order to test whether collimation results from shadowing of radiation from a small isotropic nuclear source by a thick dusty torus. The number of ionizing photons emitted by the compact nucleus is calculated from the emission-line ratios measured for gas within the cones. On the assumption that this compact nuclear source radiates isotropically, the optical-UV power incident on the torus, which is expected to be reradiated in the IR, is determined. It is found that the observed IRAS luminosities are consistent with the torus model in eight of the nine objects with sufficient data to perform the calculation. It is concluded that the data are generally consistent with collimation and reradiation by a dusty torus.
Equilibrium-torus bifurcation in nonsmooth systems

DEFF Research Database (Denmark)

Zhusubahyev, Z.T.; Mosekilde, Erik

2008-01-01

Considering a set of two coupled nonautonomous differential equations with discontinuous right-hand sides describing the behavior of a DC/DC power converter, we discuss a border-collision bifurcation that can lead to the birth of a two-dimensional invariant torus from a stable node equilibrium...... point. We obtain the chart of dynamic modes and show that there is a region of parameter space in which the system has a single stable node equilibrium point. Under variation of the parameters, this equilibrium may disappear as it collides with a discontinuity boundary between two smooth regions...... in the phase space. The disappearance of the equilibrium point is accompanied by the soft appearance of an unstable focus period-1 orbit surrounded by a resonant or ergodic torus. Detailed numerical calculations are supported by a theoretical investigation of the normal form map that represents the piecewise...
'Affine' algebras on the torus

International Nuclear Information System (INIS)

Zakkari, M.

1993-07-01

The analysis of the Kac-Moody ''like'' algebra L-circumflex 2 (G) on the torus is performed. It will be seen that the root systems construction leading to a Cartan matrix is not possible. Different twist of L-circumflex 2 λ (G) are discussed. Connections with known results are done. (author). 10 refs
Determining the Covering Factor of Compton-Thick Active Galactic Nuclei with NuSTAR

Science.gov (United States)

Brightman, M.; Balokovic, M.; Stern, D.; Arevalo, P.; Ballantyne, D. R.; Bauer, F. E.; Boggs, S. E.; Craig, W. W.; Christensen, F. E.; Zhang, W. W.

2015-01-01

The covering factor of Compton-thick (CT) obscuring material associated with the torus in active galactic nuclei (AGNs) is at present best understood through the fraction of sources exhibiting CT absorption along the line of sight (N(sub H) greater than 1.5 x 10(exp 24) cm(exp -2)) in the X-ray band, which reveals the average covering factor. Determining this CT fraction is difficult, however, due to the extreme obscuration. With its spectral coverage at hard X-rays (greater than 10 keV), Nuclear Spectroscopic Telescope Array (NuSTAR) is sensitive to the AGNs covering factor since Compton scattering of X-rays off optically thick material dominates at these energies. We present a spectral analysis of 10 AGNs observed with NuSTAR where the obscuring medium is optically thick to Compton scattering, so-called CT AGNs. We use the torus models of Brightman and Nandra that predict the X-ray spectrum from reprocessing in a torus and include the torus opening angle as a free parameter and aim to determine the covering factor of the CT gas in these sources individually. Across the sample we find mild to heavy CT columns, with N(sub H) measured from 10(exp 24) to 10(exp 26) cm(exp -2), and a wide range of covering factors, where individual measurements range from 0.2 to 0.9. We find that the covering factor, f(sub c), is a strongly decreasing function of the intrinsic 2-10 keV luminosity, L(sub X), where f(sub c) = (-0.41 +/- 0.13)log(sub 10)(L(sub X)/erg s(exp -1))+18.31 +/- 5.33, across more than two orders of magnitude in L(sub X) (10(exp 41.5) - 10(exp 44) erg s(exp -1)). The covering factors measured here agree well with the obscured fraction as a function of LX as determined by studies of local AGNs with L(sub X) greater than 10(exp 42.5) erg s(exp -1).
The geometric Schwinger model on the torus. Pt. 1

International Nuclear Information System (INIS)

Joos, H.

1990-01-01

The author analyzes the Euclidean version of the geometric Schwinger model on the torus. After the calculation of the zero mode wave functions associated with the different topological sectors, which can be expressed by θ functions defined on the two-dimensional torus, he determines the regularized effective action and discusses the propagator related to it. Finally he studies applications to the standard questions like the particle spectrum, the screening of the static potential, and the appearance of the anomaly. (HSI)
Magnetostatics of the uniformly polarized torus

DEFF Research Database (Denmark)

Beleggia, Marco; De Graef, Marc; Millev, Yonko

2009-01-01

We provide an exhaustive description of the magnetostatics of the uniformly polarized torus and its derivative self-intersecting (spindle) shapes. In the process, two complementary approaches have been implemented, position-space analysis of the Laplace equation with inhomogeneous boundary condit...
Success and failure of the plasma analogy for Laughlin states on a torus

Science.gov (United States)

Fremling, Mikael

2017-01-01

We investigate the nature of the plasma analogy for the Laughlin wave function on a torus describing the quantum Hall plateau at ν =\\frac{1}{q} . We first establish, as expected, that the plasma is screening if there are no short nontrivial paths around the torus. We also find that when one of the handles has a short circumference—i.e. the thin-torus limit—the plasma no longer screens. To quantify this we compute the normalization of the Laughlin state, both numerically and analytically. In the thin torus limit, the analytical form of the normalization simplify and we can reconstruct the normalization and analytically extend it back into the 2D regime. We find that there are geometry dependent corrections to the normalization, and this in turn implies that the plasma in the plasma analogy is not screening when in the thin torus limit. Despite the breaking of the plasma analogy in this limit, the analytical approximation is still a good description of the normalization for all tori, and also allows us to compute hall viscosity at intermediate thickness.
National Spherical Torus Experiment (NSTX)

International Nuclear Information System (INIS)

Masayuki Ono

2000-01-01

The main aim of National Spherical Torus Experiment (NSTX) is to establish the fusion physics principles of the innovative spherical torus (ST) concept. Physics outcome of the NSTX research program is relevant to near-term applications such as the Volume Neutron Source (VNS) and burning plasmas, and future applications such as the pilot and power plants. The NSTX device began plasma operations in February 1999 and the plasma current was successfully ramped up to the design value of 1 million amperes (MA) on December 14, 1999. The CHI (Coaxial Helicity Injection) and HHFW (High Harmonic Fast Wave) experiments have also started. Stable CHI discharges of up to 133 kA and 130-msec duration have been produced using 20 kA of injected current. Using eight antennas connected to two transmitters, up to 2 MW of HHFW power was successfully coupled to the plasma. The Neutral-beam Injection (NBI) heating system and associated NBI-based diagnostics such as the Charge-exchange Recombination Spectrometer (CHERS) will be operational in October 2000
Bumpy torus annulus startup

International Nuclear Information System (INIS)

Sperling, J.L.; Hamasaki, S.; Krall, N.A.

1982-01-01

In order that a stable bumpy torus plasma configuration can be attained, it is first necessary to irradiate the plasma with sufficient external power to cause annulus formation. To estimate the power required to initiate annuli, it is assumed that quasilinear electron-cyclotron heating by microwaves is the dominant electron heating mechanism. A scaling law for required microwave power is derived which shows that annulus formation is assisted by smaller cross-section areas, lower density, lower microwave frequency, and higher C-mode temperature. The scaling law is quantitatively evaluated for NBT, EBT-1, EBT-S, EBT-P, and EBT-R parameters. The resulting power estimates are consistent with the available microwave power in previous and present experiments. In larger projected bumpy tori, like EBT-P and EBT-R, it may be necessary to initiate annulus formation at densities which are lower than in the stable T-mode so that the necessary microwave power can be reduced to reasonably modest levels. It is suggested that instabilities as well as rf heating can aid the formation of bumpy torus electron annuli. Rf experiments on NBT and EBT-S would be beneficial in determining the capability of rf power to assist annulus startup
A time-dependent anisotropic plasma chemistry model of the Io plasma torus

Science.gov (United States)

Arridge, C. S.

2016-12-01

The physics of the Io plasma torus is typically modelled using one box neutral-plasma chemistry models, often referred to as neutral cloud theory models (e.g., Barbosa 1994; Delamere and Bagenal 2003). These models incorporate electron impact and photoionisation, charge exchange, molecular dissociation/recombination reactions, atomic radiatiative losses and Coulomb collisional heating. Isotropic Maxwellian distributions are usually assumed in the implementation of these models. Observationally a population of suprathermal electrons has been identified in the plasma torus and theoretically they have been shown to be important in reproducing the observed ionisation balance in the torus (e.g., Barbosa 1994). In this paper we describe an anisotropic plasma chemistry model for the Io torus that is inspired by ion cyclotron wave observations (Huddleston et al. 1994; Leisner et al. 2011), ion anisotropies due to pick up (Wilson et al. 2008), and theoretical ideas on the maintenance of the suprathermal electron population (Barbosa 1994). We present both steady state calculations and also time varying solutions (e.g., Delamere et al. 2004) where increases in the neutral source rate in the torus generates perturbations in ion anisotropies that subsequently decay over a timescale much longer than the duration of the initial perturbation. We also present a method for incorporating uncertainties in reaction rates into the model.
Nonlinear evolution of magnetic islands in a two fluid torus

International Nuclear Information System (INIS)

Sugiyama, L.E.; Park, W.

1996-01-01

A numerical model MH3D-T for the two fluid description of macroscopic evolution in a full three dimensional torus has been developed. Based on the perturbative drift ordering, generalized to arbitrary perturbation size, the model follows the full temperature evolution, including the thermal equilibration along the magnetic field. It contains the diamagnetic drifts, ion gyroviscous stress tensor, and the Hall term in Ohm's law. Electron inertia is neglected. The numerical model solves the same equations in a torus and in several simplified configurations. It has been benchmarked against the diamagnetic ω* i stabilization of the resistive m = 1, n = 1 reconnecting mode in a cylinder. The nonlinear evolution of resistive magnetic islands with m,n ≠ 1,1 in a cylinder is found to agree with previous analytic and reduced-torus results, which show that the diamagnetic rotation vanishes early in the island evolution and the saturated island size is determined by the same external driving factor Δ' as in MHD. The two fluid evolution in a full torus, however, differs from that in a cylinder and from the resistive MHD evolution. The poloidal rotation velocity undergoes a degree of poloidal momentum damping in the torus, even without neoclassical effects. The two fluid magnetic island grows faster, nonlinearly, than the resistive MHD island, and also couples different toroidal harmonics more effectively. Plasma compressibility and processes operating along the magnetic field play a much more important role than in MHD or in simple geometry. The two fluid model contains all the important neoclassical fluid effects except for the b circ ∇ circ Π parallelj viscous force terms. The addition of these terms is in progress
ITER - torus vacuum pumping system remote handling issues

International Nuclear Information System (INIS)

Stringer, J.

1992-11-01

This report describes further design issues concerning remote maintenance of torus vacuum pumping systems options for ITER. The key issues under investigation in this report are flask support systems for valve seal exchange operations for the compound cryopump scheme and remote maintenance of a proposed multiple turbomolecular pump (TMP) system, an alternative ITER torus exhaust pumping option. Previous studies have shown that the overhead support methods for seal exchange flask equipment could malfunction due to valve/flask misalignment. A floor-mounted support system is described in this report. This scheme provides a more rigid support system for seal exchange operations. An alternative torus pumping system, based on the use of multiple TMPs, is studied from a remote maintenance standpoint. In this concept, centre distance spacing for pump/valve assemblies is too restrictive for remote maintenance. Recommendations are made for adequate spacing of these assemblies based on commercially-available 0.8 m and 1.0 m diameter valves. Fewer pumps will fit in this arrangement, which implies a need for larger TMPs. Pumps of this size are not commercially available. Other concerns regarding the servicing and storage of remote handling equipment in cells are also identified. (9 figs.)
The CLAS12 Torus Detector Magnet at Jefferson Laboratory

Energy Technology Data Exchange (ETDEWEB)

Luongo, Cesar [Jefferson Lab; Ballard, Joshua [Jefferson Lab; Biallas, George [Jefferson Lab; Elouadrhiri, Latifa [Jefferson Lab; Fair, Ruben [Jefferson Lab; Ghoshal, Probir [Jefferson Lab; Kashy, Dave [Jefferson Lab; Legg, Robert [Jefferson Lab; Pastor, Orlando [Jefferson Lab; Rajput-Ghoshal, Renuka [Jefferson Lab; Rode, Claus [Jefferson Lab; Wiseman, Mark [Jefferson Lab; Young, Glenn [Jefferson Lab; Elementi, Luciano [Fermilab; Krave, Steven [Fermilab; Makarov, Alexander [Fermilab; Nobrega, Fred [Fermilab; Velev, George [Fermilab

2015-12-17

The CLAS12 Torus is a toroidal superconducting magnet, which is part of the detector for the 12-GeV accelerator upgrade at Jefferson Laboratory (JLab). The coils were wound/fabricated by Fermilab, with JLab responsible for all other parts of the project scope, including design, integration, cryostating the individual coils, installation, cryogenics, I&C, etc. This paper provides an overview of the CLAS12 Torus magnet features and serves as a status report of its installation in the experimental hall. Completion and commissioning of the magnet is expected in 2016.

A disrupted molecular torus around Eta Carinae as seen in 12CO with ALMA

Science.gov (United States)

Smith, Nathan; Ginsburg, Adam; Bally, John

2018-03-01

We present Atacama Large Millimeter Array (ALMA) observations of 12CO 2-1 emission from circumstellar material around the massive star Eta Carinae (η Car). These observations reveal new structural details about the cool equatorial torus located ˜4000 au from the star. The CO torus is not a complete azimuthal loop, but rather, is missing its near side, which appears to have been cleared away. The missing material matches the direction of apastron in the eccentric binary system, making it likely that η Car's companion played an important role in disrupting portions of the torus soon after ejection. Molecular gas seen in ALMA data aligns well with the cool dust around η Car previously observed in mid-infrared (IR) maps, whereas hot dust resides at the inner surface of the molecular torus. The CO also coincides with the spatial and velocity structure of near-IR H2 emission. Together, these suggest that the CO torus seen by ALMA is actually the pinched waist of the Homunculus polar lobes, which glows brightly because it is close to the star and warmer than the poles. The near side of the torus appears to be a blowout, associated with fragmented equatorial ejecta. We discuss implications for the origin of various features north-west of the star. CO emission from the main torus implies a total gas mass in the range of 0.2-1 M⊙ (possibly up to 5 M⊙ or more, although with questionable assumptions). Deeper observations are needed to constrain CO emission from the cool polar lobes.
Feasibility study for the Spherical Torus Experiment

International Nuclear Information System (INIS)

Lazarus, E.A.; Attenberger, S.E.; Baylor, L.R.

1985-10-01

The design of the Spherical Torus Experiment (STX) is discussed. The physics of the plasma are given in a magnetohydrodynamic model. The structural aspects and instrumentation of the device are described. 19 refs., 103 figs
The classical theory of the bumpy torus relativistic annulus

International Nuclear Information System (INIS)

Hamasaki, S.; Krall, N.A.; Sperling, J.L.

1983-01-01

The relativistic electron annulus is a critical component of the bumpy torus magnetic fusion concept. An analysis of the annulus is presented in which the ring steady state is determined by the explicit balance of quasi-linear heating and classical losses, i.e. collisions and synchrotron radiation. Both anisotropy and loss-cone effects are included in the formalism. It is demonstrated that a large number of electron cyclotron harmonics, not just the first and second, contribute in an appreciable way to annulus steady state and power balance. Without a loss cone, the analysis reproduces the relativistic passing electron population observed in bumpy tori on confined drift surfaces near the centre of the bumpy torus cross-section. Loss-cone effects permit an annulus population with large perpendicular pressure to exist. It is shown that the balance between quasi-linear heating and the classical losses cannot account for the experimental scaling of bumpy torus annulus temperature; therefore, processes not included in the classical ring power balance model must contribute in a non-trivial way to observed annulus properties. (author)
Torus as phase space: Weyl quantization, dequantization, and Wigner formalism

Energy Technology Data Exchange (ETDEWEB)

Ligabò, Marilena, E-mail: marilena.ligabo@uniba.it [Dipartimento di Matematica, Università di Bari, I-70125 Bari (Italy)

2016-08-15

The Weyl quantization of classical observables on the torus (as phase space) without regularity assumptions is explicitly computed. The equivalence class of symbols yielding the same Weyl operator is characterized. The Heisenberg equation for the dynamics of general quantum observables is written through the Moyal brackets on the torus and the support of the Wigner transform is characterized. Finally, a dequantization procedure is introduced that applies, for instance, to the Pauli matrices. As a result we obtain the corresponding classical symbols.
An alternative to the compact torus ICF driver

International Nuclear Information System (INIS)

Latter, A.L.; Martinelli, E.A.

1992-11-01

Plasma guns have been used in the Controlled Thermonuclear Reaction (CTR) Program to inject energetic deuterium-tritium plasma into a magnetic confinement machine, also for dense-plasma-focus devices to achieve fusion utilizing Z-pinches. In this report we propose another CTR application of a plasma gun: accelerating the plasma in a coaxial geometry to a speed in the neighborhood of a centimeter per shake with a total kinetic energy of about 20 MJ. The kinetic energy is efficiently converted to x-rays in a time of about a shake, and the x-ray pulse is used to implode an Inertial Confinement Fusion (ICF) capsule. As far as we know the plasma gun application we are proposing has not been explored before, but we observe that the LLNL Compact Torus Program hopes to accelerate a compact-torus-plasma to a comparable speed and energy and, in one of its applications, to generate x-rays for ICF purposes. In fact, the only difference between the LLNL Compact Torus Program and what we are proposing is that our plasma does not rely on imbedded magnetic fields and currents to minimize instabilities. We minimize instabilities by snowplowing the plasma to its required speed in a single shock. Which approach is better requires additional investigation
Smooth invariant densities for random switching on the torus

Science.gov (United States)

Bakhtin, Yuri; Hurth, Tobias; Lawley, Sean D.; Mattingly, Jonathan C.

2018-04-01

We consider a random dynamical system obtained by switching between the flows generated by two smooth vector fields on the 2d-torus, with the random switchings happening according to a Poisson process. Assuming that the driving vector fields are transversal to each other at all points of the torus and that each of them allows for a smooth invariant density and no periodic orbits, we prove that the switched system also has a smooth invariant density, for every switching rate. Our approach is based on an integration by parts formula inspired by techniques from Malliavin calculus.
Next-Step Spherical Torus Experiment and Spherical Torus Strategy in the Fusion Energy Development Path

International Nuclear Information System (INIS)

Ono, M.; Peng, M.; Kessel, C.; Neumeyer, C.; Schmidt, J.; Chrzanowski, J.; Darrow, D.; Grisham, L.; Heitzenroeder, P.; Jarboe, T.; Jun, C.; Kaye, S.; Menard, J.; Raman, R.; Stevenson, T.; Viola, M.; Wilson, J.; Woolley, R.; Zatz, I.

2003-01-01

A spherical torus (ST) fusion energy development path which is complementary to proposed tokamak burning plasma experiments such as ITER is described. The ST strategy focuses on a compact Component Test Facility (CTF) and higher performance advanced regimes leading to more attractive DEMO and Power Plant scale reactors. To provide the physics basis for the CTF an intermediate step needs to be taken which we refer to as the ''Next Step Spherical Torus'' (NSST) device and examine in some detail herein. NSST is a ''performance extension'' (PE) stage ST with the plasma current of 5-10 MA, R = 1.5 m, and Beta(sub)T less than or equal to 2.7 T with flexible physics capability. The mission of NSST is to: (1) provide a sufficient physics basis for the design of CTF, (2) explore advanced operating scenarios with high bootstrap current fraction/high performance regimes, which can then be utilized by CTF, DEMO, and Power Plants, and (3) contribute to the general plasma/fusion science of high beta toroidal plasmas. The NSST facility is designed to utilize the Tokamak Fusion Test Reactor (or similar) site to minimize the cost and time required for the design and construction
A New Cross-By-Pass-Torus Architecture Based on CBP-Mesh and Torus Interconnection for On-Chip Communication.

Directory of Open Access Journals (Sweden)

Usman Ali Gulzari

Full Text Available A Mesh topology is one of the most promising architecture due to its regular and simple structure for on-chip communication. Performance of mesh topology degraded greatly by increasing the network size due to small bisection width and large network diameter. In order to overcome this limitation, many researchers presented modified Mesh design by adding some extra links to improve its performance in terms of network latency and power consumption. The Cross-By-Pass-Mesh was presented by us as an improved version of Mesh topology by intelligent addition of extra links. This paper presents an efficient topology named Cross-By-Pass-Torus for further increase in the performance of the Cross-By-Pass-Mesh topology. The proposed design merges the best features of the Cross-By-Pass-Mesh and Torus, to reduce the network diameter, minimize the average number of hops between nodes, increase the bisection width and to enhance the overall performance of the network. In this paper, the architectural design of the topology is presented and analyzed against similar kind of 2D topologies in terms of average latency, throughput and power consumption. In order to certify the actual behavior of proposed topology, the synthetic traffic trace and five different real embedded application workloads are applied to the proposed as well as other competitor network topologies. The simulation results indicate that Cross-By-Pass-Torus is an efficient candidate among its predecessor's and competitor topologies due to its less average latency and increased throughput at a slight cost in network power and energy for on-chip communication.
An experimental determination of the hot electron ring geometry in a Bumpy Torus and its implications for Bumpy Torus stability

International Nuclear Information System (INIS)

Hillis, D.L.; Wilgen, J.B.; Bigelow, T.S.; Jaeger, E.F.; Swain, D.W.; Hankins, O.E.; Juhala, R.E.

1986-10-01

The hot electron rings of the ELMO Bumpy Torus (EBT) [Plasma Physics and Controlled Nuclear Fusion (IAEA, Vienna, 1975), Vol. II, p. 141] are formed by electron cyclotron resonance heating (ECRH) and have an electron temperature of 350 to 500 keV. The original intention of these hot electron rings was to provide a local minimum in the magnetic field and, thereby, stabilize the simple interchange and flute modes, which are inherent in a closed field line bumpy torus. To evaluate the electron energy density of the EBT rings and determine if enough stored energy is present to provide a local minimum in the magnetic field, a detailed understanding of the spatial distribution of the rings is imperative. The purpose of this report is to measure the ring thickness and investigate its implications for bumpy torus stability. The spatial location and radial profile of the hot electron ring are measured with a unique metal ball pellet injector, which injects small metallic balls into the EBT ring plasma. From these measurements the radial extent (or ring thickness) is about 5 to 7 cm full width at half maximum for typical EBT operation, which is much larger than previously expected. These measurements and recent modeling of the EBT plasma indicate that the hot electron ring's stored energy may not be sufficient to produce a local minimum in the magnetic field
MORSE-CGT Monte Carlo radiation transport code with the capability of the torus geometric treatment

International Nuclear Information System (INIS)

Deng Li

1990-01-01

The combinatorial geometry package CGT with the capability of the torus geometric treatment is introduced. It is get by developing the combinatorial geometry package CG. The CGT package can be transplanted to those codes which the CG package is being used and makes them also with the capability. The MORSE-CGT code can be used to solve the neutron, gamma-ray or coupled neutron-gamma-ray transport problems and time dependence for both shielding and criticality problems in torus system or system which is produced by arbitrary finite combining torus with torus or other bodies in CG package and it can also be used to design the blanket and compute shielding for TOKAMAK Fusion-Fission Hybrid Reactor
ELMO Bumpy Torus

International Nuclear Information System (INIS)

Berry, L.A.; Hedrick, C.L.; Uckan, N.A.

1979-03-01

The ELMO Bumpy Torus (EBT) program of experiment, theory, and reactor studies has been a remarkably successful one. In the five years since EBT-I began operating, work has progressed from a demonstration of macrostability to an increasingly detailed understanding of transport properties. Collisionless scaling (tau/sub E/ increases with temperature) has been observed, and the magnitude of the energy confinement time is consistent with neoclassical theory. Experiments on EBT-S (for scale) are now being conducted at the increased magnetic field levels and higher microwave power and frequency made possible by a 28-GHz gyrotron development program. A review of the program is given
Recent results from the National Spherical Torus Experiment

International Nuclear Information System (INIS)

Maingi, R; Bell, M G; Bell, R E; Bialek, J; Bourdelle, C; Bush, C E; Darrow, D S; Fredrickson, E D; Gates, D A; Gilmore, M; Gray, T; Jarboe, T R; Johnson, D W; Kaita, R; Kaye, S M; Kubota, S; Kugel, H W; LeBlanc, B P; Maqueda, R J; Mastrovito, D; Medley, S S; Menard, J E; Mueller, D; Nelson, B A; Ono, M; Paoletti, F; Park, H K; Paul, S F; Peebles, T; Peng, Y-K M; Phillips, C K; Raman, R; Rosenberg, A L; Roquemore, A L; Ryan, P M; Sabbagh, S A; Skinner, C H; Soukhanovskii, V A; Stutman, D; Swain, D W; Synakowski, E J; Taylor, G; Wilgen, J; Wilson, J R; Wurden, G A; Zweben, S J

2003-01-01

The National Spherical Torus Experiment (NSTX) is a low aspect-ratio fusion research facility whose research goal is to make a determination of the attractiveness of the spherical torus concept in the areas of high-β stability, confinement, current drive, and divertor physics. Remarkable progress was made in extending the operational regime of the device in FY 2002. In brief, β t of 34% and β N of 6.5 were achieved. H-mode became the main operational regime, and energy confinement exceeded conventional aspect-ratio tokamak scalings. Heating was demonstrated with the radiofrequency antenna, and signatures of current drive were observed. Current initiation with coaxial helicity injection produced discharges of 400 kA, and first measurements of divertor heat flux profiles in H-mode were made
Compact torus accelerator as a driver for ICF

International Nuclear Information System (INIS)

Tobin, M.T.; Meier, W.R.; Morse, E.C.

1986-01-01

The authors have carried out further investigations of the technical issues associated with using a compact torus (CT) accelerator as a driver for inertial confinement fusion (ICF). In a CT accelerator, a magnetically confined, torus-shaped plasma is compressed, accelerated, and focused by two concentric electrodes. After its initial formation, the torus shape is maintained for lifetimes exceeding 1 ms by inherent poloidal and toroidal currents. Hartman suggests acceleration and focusing of such a plasma ring will not cause dissolution within certain constraints. In this study, we evaluated a point design based on an available capacitor bank energy of 9.2 MJ. This accelerator, which was modeled by a zero-dimensional code, produces a xenon plasma ring with a 0.73-cm radius, a velocity of 4.14 x 10 9 cm/s, and a mass of 4.42 μg. The energy of the plasma ring as it leaves the accelerator is 3.8 MJ, or 41% of the capacitor bank energy. Our studies confirm the feasibility of producing a plasma ring with the characteristics required to induce fusion in an ICF target with a gain greater than 50. The low cost and high efficiency of the CT accelerator are particularly attractive. Uncertainties concerning propagation, accelerator lifetime, and power supply must be resolved to establish the viability of the accelerator as an ICF driver
SDN Data Center Performance Evaluation of Torus and Hypercube Interconnecting Schemes

DEFF Research Database (Denmark)

Andrus, Bogdan-Mihai; Vegas Olmos, Juan José; Mehmeri, Victor

2015-01-01

— By measuring throughput, delay, loss-rate and jitter, we present how SDN framework yields a 45% performance increase in highly interconnected topologies like torus and hypercube compared to current Layer2 switching technologies, applied to data center architectures......— By measuring throughput, delay, loss-rate and jitter, we present how SDN framework yields a 45% performance increase in highly interconnected topologies like torus and hypercube compared to current Layer2 switching technologies, applied to data center architectures...
Minimal Liouville gravity on the torus via the Douglas string equation

International Nuclear Information System (INIS)

Spodyneiko, Lev

2015-01-01

In this paper we assume that the partition function in minimal Liouville gravity (MLG) obeys the Douglas string equation. This conjecture makes it possible to compute the torus correlation numbers in (3,p) MLG. We perform this calculation using also the resonance relations between the coupling constants in the KdV frame and in the Liouville frame. We obtain explicit expressions for the torus partition function and for the one- and two-point correlation numbers. (paper)
Elmo Bumpy Torus Reactor

International Nuclear Information System (INIS)

McAlees, D.G.; Uckan, N.A.; Lidsky, L.M.

1976-01-01

In the Elmo Bumpy Torus Reactor (EBTR) study the feasibility of achieving a fusion power plant based on the EBT confinement concept was evaluated. If the present understanding of the physics can be extrapolated to reactor scale devices the reactor could operate at high beta, high power density, and at steady state. The high aspect ratio of the device eases the accessibility, structural design and remote maintenance problems which are common to low aspect ratio machines. A version of the EBTR reference design described here could be constructed with only minor extrapolations in available technology
Numerical simulation of torus breakdown to chaos in an atmospheric-pressure dielectric barrier discharge

International Nuclear Information System (INIS)

Zhang, J.; Wang, Y. H.; Wang, D. Z.

2013-01-01

Understanding the routes to chaos occurring in atmospheric-pressure dielectric barrier discharge systems by changing controlling parameters is very important to predict and control the dynamical behaviors. In this paper, a route of a quasiperiodic torus to chaos via the strange nonchaotic attractor is observed in an atmospheric-pressure dielectric barrier discharge driven by triangle-wave voltage. By increasing the driving frequency, the discharge system first bifurcates to a quasiperiodic torus from a stable single periodic state, and then torus and phase-locking periodic state appear and disappear alternately. In the meantime, the torus becomes increasingly wrinkling and stretching, and gradually approaches a fractal structure with the nonpositive largest Lyapunov exponent, i.e., a strange nonchaotic attractor. After that, the discharge system enters into chaotic state. If the driving frequency is further increased, another well known route of period-doubling bifurcation to chaos is also observed
Numerical simulation of torus breakdown to chaos in an atmospheric-pressure dielectric barrier discharge

Energy Technology Data Exchange (ETDEWEB)

Zhang, J.; Wang, Y. H.; Wang, D. Z. [Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

2013-08-15

Understanding the routes to chaos occurring in atmospheric-pressure dielectric barrier discharge systems by changing controlling parameters is very important to predict and control the dynamical behaviors. In this paper, a route of a quasiperiodic torus to chaos via the strange nonchaotic attractor is observed in an atmospheric-pressure dielectric barrier discharge driven by triangle-wave voltage. By increasing the driving frequency, the discharge system first bifurcates to a quasiperiodic torus from a stable single periodic state, and then torus and phase-locking periodic state appear and disappear alternately. In the meantime, the torus becomes increasingly wrinkling and stretching, and gradually approaches a fractal structure with the nonpositive largest Lyapunov exponent, i.e., a strange nonchaotic attractor. After that, the discharge system enters into chaotic state. If the driving frequency is further increased, another well known route of period-doubling bifurcation to chaos is also observed.
Wendelstein 7-X Torus Hall Layout and System Integration

International Nuclear Information System (INIS)

Hartmann, D.; Damiani, C.; Hartfuss, H.-J.; Krampitz, R.; Neuner, U.

2006-01-01

Wendelstein 7-X is an experimental fusion device presently under construction in Greifswald, Germany, to study the stellarator concept at reactor relevant parameters und steady-state conditions. The heart of the machine consists of the torus that houses the superconducting coils and the plasma vacuum vessel. It is located nearly in the center of a 30 m x 30 m x 20 m hall. A large number of components need to be placed in close proximity of the torus to provide the system with the required means, e.g. cryogenic gases, cooling water, electricity, and to integrate it with the peripheral diagnostic and heating components. The arrangement of these components has to be supported by suitable structures, and has to be optimized to allow for installation, maintenance, and repair. In addition, space has to be provided for escape routes and for sufficient distance between components that could negatively influence each other's performance, etc. The layout of the components has been done over many years using 3D CAD software. It was based on simple geometric models of the components and of the additionally required space. Presently the layout design is being detailed and updated by replacing the original coarse models with more refined estimates or - in some cases - with as-built models. All interface requirements are carefully taken into account. Detailed routing was specified for the cryo and cooling water supply lines whose design and installation is outsourced. Due to the limited space available and severely restricted access during experimental campaigns, the requirement to put auxiliary components like electronic racks into the torus hall is being queried. The paper summarizes the present state of the component layout in the torus hall, and how the peripheral supply, diagnostics, and heating systems are integrated into the machine. (author)
RefleX: X-ray absorption and reflection in active galactic nuclei for arbitrary geometries

Science.gov (United States)

Paltani, S.; Ricci, C.

2017-11-01

Reprocessed X-ray radiation carries important information about the structure and physical characteristics of the material surrounding the supermassive black hole (SMBH) in active galactic nuclei (AGN). We report here on a newly developed simulation platform, RefleX, which allows to reproduce absorption and reflection by quasi-arbitrary geometries. We show here the reliability of our approach by comparing the results of our simulations with existing spectral models such as pexrav, MYTorus and BNTorus. RefleX implements both Compton scattering on free electrons and Rayleigh scattering and Compton scattering on bound electrons. We show the effect of bound-electron corrections on a torus geometry simulated like in MYTorus. We release with this paper the RefleX executable, as well as RXTorus, a model that assumes absorption and reflection from a torus with a varying ratio of the minor to major axis of the torus. To allow major flexibility RXTorus is also distributed in three components: absorbed primary emission, scattered radiation and fluorescent lines. RXTorus is provided for different values of the abundance, and with (atomic configuration) or without (free-electron configuration) taking into account Rayleigh scattering and bound electrons. We apply the RXTorus model in both configurations on the XMM-Newton and NuSTAR spectrum of the Compton-thick AGN NGC 424 and find that the models are able to reproduce very well the observations, but that the assumption on the bound or free state of the electrons has significant consequences on the fit parameters. RefleX executable, user manual and example models are available at http://www.astro.unige.ch/reflex. A copy of the RefleX executable is also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/607/A31

Particle on a torus knot: Constrained dynamics and semi-classical quantization in a magnetic field

Energy Technology Data Exchange (ETDEWEB)

Das, Praloy, E-mail: praloydasdurgapur@gmail.com; Pramanik, Souvik, E-mail: souvick.in@gmail.com; Ghosh, Subir, E-mail: subirghosh20@gmail.com

2016-11-15

Kinematics and dynamics of a particle moving on a torus knot poses an interesting problem as a constrained system. In the first part of the paper we have derived the modified symplectic structure or Dirac brackets of the above model in Dirac’s Hamiltonian framework, both in toroidal and Cartesian coordinate systems. This algebra has been used to study the dynamics, in particular small fluctuations in motion around a specific torus. The spatial symmetries of the system have also been studied. In the second part of the paper we have considered the quantum theory of a charge moving in a torus knot in the presence of a uniform magnetic field along the axis of the torus in a semiclassical quantization framework. We exploit the Einstein–Brillouin–Keller (EBK) scheme of quantization that is appropriate for multidimensional systems. Embedding of the knot on a specific torus is inherently two dimensional that gives rise to two quantization conditions. This shows that although the system, after imposing the knot condition reduces to a one dimensional system, even then it has manifested non-planar features which shows up again in the study of fractional angular momentum. Finally we compare the results obtained from EBK (multi-dimensional) and Bohr–Sommerfeld (single dimensional) schemes. The energy levels and fractional spin depend on the torus knot parameters that specifies its non-planar features. Interestingly, we show that there can be non-planar corrections to the planar anyon-like fractional spin.
Dynamics of magnetic fields in Maxwell, Yang-Mills and Chern-Simons theories on the torus

International Nuclear Information System (INIS)

Burgess, M.; McLachlan, A.; Toms, D.J.

1992-01-01

The problem of uniform magnetic fields passing perpendicularly through a 2-torus, Abelian and Non-Abelian, is considered. Focus is on dynamical effects of non-integrable phases on the torus at non zero B and from magnetic fields themselves in the vacuum. The spectrum is computed and is shown to be always independent of the non-integrable phases on the torus. It is concluded that a Chern-Simons term will always be induced by radiative corrections to fermions on the torus when B ≠ 0. The special case of an electromagnetically uncharged anyon gas in noted and shown to be a system whose spectrum can depend on the non-integrable phases in the two torus directions, subject to a consistency requirement. In three and four dimensions, dynamical symmetry breaking of non-Abelian fields and associated condensate formation is possible by radiative corrections. The classification on non-Abelian magnetic fields in terms of ''flux integers'' is discussed, and a method for obtaining such integers for an arbitrary gauge algebra is presented. This provides a rigorous generalisation of Hooft's su (2) classification. 72 refs., 5 figs
Simulations of the Effects of Jupiter's Plasma Torus on Io's Pele Plume

Science.gov (United States)

McDoniel, William; Goldstein, David B.; Varghese, Philip L.; Trafton, Laurence M.

2014-11-01

Io’s plumes rise hundreds of kilometers above its surface and sublimation atmosphere, presenting large targets for incoming ions from Jupiter’s plasma torus. The direct simulation Monte Carlo method is used to model the gas plume at Pele and its interaction with the Jovian plasma torus. Chemical reactions resulting from ion impacts in a plume change its composition and energy from the impacts changes the plume’s structure (asymmetrically). The presence of non-condensible daughter species in a warmer plume canopy produces a more diffuse deposition ring on Io’s surface, compared to simulations without plasma. Energized molecules also escape from the plume, forming a diffuse cloud of fast particles above the plume’s canopy, which may function to resupply the plasma torus and which suggests a mechanism for lofting other species to very high altitudes.
ELMO Bumpy Torus fusion-reactor design study

International Nuclear Information System (INIS)

Bathke, C.G.; Krakowski, R.A.

1981-01-01

A complete power plant design of a 1200-MWe ELMO Bumpy Torus Reactor (EBTR) is described that emphasizes those features that are unique to the EBT confinement concept, with subsystems and balance-of-plant items that are generic to magnetic fusion being adopted from past, more extensive tokamak reactor designs
On the existence of star products on quotient spaces of linear Hamiltonian torus actions

DEFF Research Database (Denmark)

Herbig, Hans-Christian; Iyengar, Srikanth B.; Pflaum, Markus J.

2009-01-01

that the Koszul complex on the moment map of an effective linear Hamiltonian torus action is acyclic. We rephrase the nonpositivity condition of Arms and Gotay (Adv Math 79(1):43–103, 1990) for linear Hamiltonian torus actions. It follows that reduced spaces of such actions admit continuous star products....
Determination of the size of the dust torus in H0507+164 through optical and infrared monitoring

Science.gov (United States)

Mandal, Amit Kumar; Rakshit, Suvendu; Kurian, Kshama S.; Stalin, C. S.; Mathew, Blesson; Hoenig, Sebastian; Gandhi, Poshak; Sagar, Ram; Pandge, M. B.

2018-04-01

The time delay between flux variations in different wavelength bands can be used to probe the inner regions of active galactic nuclei (AGNs). Here, we present the first measurements of the time delay between optical and near-infrared (NIR) flux variations in H0507+164, a nearby Seyfert 1.5 galaxy at z = 0.018. The observations in the optical V-band and NIR J, H, and Ks bands carried over 35 epochs during the period 2016 October to 2017 April were used to estimate the inner radius of the dusty torus. From a careful reduction and analysis of the data using cross-correlation techniques, we found delayed responses of the J, H, and Ks light curves to the V-band light curve. In the rest frame of the source, the lags between optical and NIR bands are found to be 27.1^{+13.5}_{-12.0} d (V versus J), 30.4^{+13.9}_{-12.0} d (V versus H) and 34.6^{+12.1}_{-9.6} d (V versus Ks). The lags between the optical and different NIR bands are thus consistent with each other. The measured lags indicate that the inner edge of dust torus is located at a distance of 0.029 pc from the central ultraviolet/optical AGN continuum. This is larger than the radius of the broad line region of this object determined from spectroscopic monitoring observations thereby supporting the unification model of AGN. The location of H0507+164 in the τ-MV plane indicates that our results are in excellent agreement with the now known lag-luminosity scaling relationship for dust in AGN.
Torus palatinus | Naidoo | SA Journal of Radiology

African Journals Online (AJOL)

Kupffer and Bessel-Hagen coined the term torus palatinus in 1879 for a benign osseous protuberance arising from the midline of the hard palate. Tori are present in approximately 20% of the population and are occult until adulthood. Recent advances in modern radiology have led to improved evaluation and diagnosis of ...
Electron distribution functions in Io plasma torus

International Nuclear Information System (INIS)

Boev, A.G.

2003-01-01

Electron distribution functions measured by the Voyager 1 in different shares of the Io plasma torus are explained. It is proved that their suprathermal tails are formed by the electrical field induced by the 'Jupiter wind'. The Maxwellian parts of all these spectra characterize thermal equilibrium populations of electrons and the radiation of exited ions
A 12 coil superconducting bumpy torus magnet facility for plasma research

Science.gov (United States)

Roth, J. R.; Holmes, A. D.; Keller, T. A.; Krawczonek, W. M.

1972-01-01

A summary is presented of the performance of the two-coil superconducting pilot rig which preceded the NASA Lewis bumpy torus. This pilot rig was operated for 550 experimental runs over a period of 7 years. The NASA Lewis bumpy torus facility consists of 12 superconducting coils, each with a 19 cm in diameter and capable of producing magnetic field strengths of 3.0 teslas on their axes. The magnets are equally spaced around a major circumference 1.52 m in diameter, and are mounted with the major axis of the torus vertical in a single vacuum tank 2.59 m in diameter. The design value of maximum magnetic field on the magnetic axis (3.0 teslas) was reached and exceeded. A maximum magnetic field of 3.23 teslas was held for a period of 60 minutes, and the coils did not go to normal. When the coils were charged to a maximum magnetic field of 3.35 teslas, the coil system was driven normal without damage to the facility.
Legendrian and transverse cables of positive torus knots

DEFF Research Database (Denmark)

B. Etnyre, John; la Fountain, Douglas James; Tosun, Bulent

In this paper we classify Legendrian and transverse knots in the knot types obtained from positive torus knots by cabling. This classification allows us to demonstrate several new phenomena. Specifically, we show there are knot types that have non-destabilizable Legendrian representatives whose T...
Five-dimensional gauge theory and compactification on a torus

Science.gov (United States)

Haghighat, Babak; Vandoren, Stefan

2011-09-01

We study five-dimensional minimally supersymmetric gauge theory compactified on a torus down to three dimensions, and its embedding into string/M-theory using geometric engineering. The moduli space on the Coulomb branch is hyperkähler equipped with a metric with modular transformation properties. We determine the one-loop corrections to the metric and show that they can be interpreted as worldsheet and D1-brane instantons in type IIB string theory. Furthermore, we analyze instanton corrections coming from the solitonic BPS magnetic string wrapped over the torus. In particular, we show how to compute the path-integral for the zero-modes from the partition function of the M5 brane, or, using a 2d/4d correspondence, from the partition function of N=4 SYM theory on a Hirzebruch surface.
Influence of globalmagnetic perturbations on plasma behavior in Elmo Bumpy Torus

International Nuclear Information System (INIS)

Quon, B.H.; Dandl, R.A.; Colestock, P.L.; Bieniosek, F.M.; Ikegami, H.

1979-02-01

The sensitivity of plasma confinement to magnetic field error effects has been tested experimentally using externally introduced global field errors on the ELMO Bumpy Torus (EBT). Below a critical error field (deltaB/sub r//B)/sub cr/ of approx. = to 0.6-1 x 10 -3 the plasma was observed to be essentially free from convective cells, toroidal currents, and instabilities. This observed critical value is comparable to a neoclassical critical field error (deltaB/sub r//B)/sub cr/ approx. = rho/R, the ratio of the ion Larmor radius to the major radius of the torus
Spherical torus (ST) concept and its reactor implications

International Nuclear Information System (INIS)

Peng, Y.K.M.; Lazarus, E.A.; Miller, R.L.; Carreras, B.A.; Hogan, J.T.; Krakowski, R.A.; Seed, T.J.; Zubrin, R.M.; Schnurr, N.M.

1986-01-01

A brief description of the spherical torus design is given. The design concept includes resistive demountable toroidal field coils, poloidal divertor for impurity control, oscillating-field current maintenance, RF initiation and ramp-up of the plasma current, and flowing liquid-metal breeding blanket. 4 refs., 6 figs
CPRF/ZTH front-end torus design and fabrication status

International Nuclear Information System (INIS)

Ballard, E.O.; Baker, C.; Gomez, T.; Prince, P.P.; Smith, R.L.

1989-01-01

Design of the ZTH front-end torus has been completed for a new generation Reversed Field Pinch (RFP) machine to be assembled at Los Alamos National Laboratory during FY 92. The Confinement Physics Research Facility (CPRF) houses the ZTH front-end torus. The ZTH torus consists of an Inconel 625 vacuum vessel supported by an external electrically conducting 304L stainless steel shell. Interspace support rings support the vacuum vessel to the shell and also provide accurate radial support for the interspace electrical diagnostics. The shell also supports 48 toroidal field coils that are mounted to the shell's external surface. The shell consists of an explosion bonded stainless steel-copper composite with water-cooling tube assemblies attached to the outer surface. The 0.135-in. thick copper is on the inside surface of the shell, and provides an electrically conducting path with the required electrical time constant of 50 ms. The shell plate will be formed to the required toroidal configuration, after which the poloidal and toroidal flanges will be welded to the structure and machined. The Inconel vacuum vessel consists of bellows segments, armor support rings, and diagnostic stations welded together to form the complete vacuum vessel assembly. The necessity for accurate positioning of the vacuum vessel within the shell requires that the shell and vacuum vessel be fabricated with major diameter tolerances within 0.050-in. true position of the nominal diameters of 188.0-in. and 188.820-in., respectively. 7 figs
Organization of the torus longitudinalis in the rainbow trout (Oncorhynchus mykiss): an immunohistochemical study of the GABAergic system and a DiI tract-tracing study.

Science.gov (United States)

Folgueira, Mónica; Sueiro, Catalina; Rodríguez-Moldes, Isabel; Yáñez, Julián; Anadón, Ramón

2007-07-10

The torus longitudinalis (TL) is a tectum-associated structure of actinopterygian fishes. The organization of the TL of rainbow trout was studied with Nissl staining, Golgi methods, immunocytochemistry with antibodies to gamma-aminobutyric acid (GABA), glutamic acid decarboxylase (GAD), and the GABA(A) receptor subunits delta and beta2/beta 3, and with tract tracing methods. Two types of neuron were characterized: medium-sized GABAergic neurons and small GABA-negative granule cells. GABA(A) receptor subunit delta-like immunoreactivity delineated two different TL regions, ventrolateral and central. Small GABAergic cells were also observed in marginal and periventricular strata of the optic tectum. These results indicate the presence of local GABAergic inhibitory circuits in the TL system. For tract-tracing, a lipophilic dye (DiI) was applied to the TL and to presumed toropetal nuclei or toral targets. Toropetal neurons were observed in the optic tectum, in pretectal (central, intermediate, and paracommissural) nuclei, in the subvalvular nucleus, and associated with the pretectocerebellar tract. Torofugal fibers were numerous in the stratum marginale of the optic tectum. Toropetal pretectal nuclei also project to the cerebellum, and a few TL cells project to the cerebellar corpus. The pyramidal cells of the trout tectum were also studied by Golgi methods and local DiI labeling. The connections of trout TL revealed here were more similar to those recently reported in carp and holocentrids (Ito et al. [2003] J. Comp. Neurol. 457:202-211; Xue et al. [2003] J. Comp. Neurol. 462:194-212), than to those reported in earlier studies. However, important differences in organization of toropetal nuclei were noted between salmonids and these other teleosts. (c) 2007 Wiley-Liss, Inc.
PHOTOCHEMISTRY IN THE INNER LAYERS OF CLUMPY CIRCUMSTELLAR ENVELOPES: FORMATION OF WATER IN C-RICH OBJECTS AND OF C-BEARING MOLECULES IN O-RICH OBJECTS

International Nuclear Information System (INIS)

Agundez, Marcelino; Cernicharo, Jose; Guelin, Michel

2010-01-01

A mechanism based on the penetration of interstellar ultraviolet photons into the inner layers of clumpy circumstellar envelopes (CSEs) around asymptotic giant branch stars is proposed to explain the non-equilibrium chemistry observed in such objects. We show through a simple modeling approach that in CSEs with a certain degree of clumpiness or with moderately low mass loss rates (a few 10 -7 M sun yr -1 ) a photochemistry can take place in the warm and dense inner layers, inducing important changes in the chemical composition. In carbon-rich objects water vapor and ammonia would be formed with abundances of 10 -8 -10 -6 relative to H 2 , while in oxygen-rich envelopes ammonia and carbon-bearing molecules such as HCN and CS would form with abundances of 10 -9 -10 -7 relative to H 2 . The proposed mechanism would explain the recent observation of warm water vapor in the carbon-rich envelope IRC+10216 with the Herschel Space Observatory and predict that H 2 O should be detectable in other carbon-rich objects.
Design and implementation of fast charging circuit for repetitive compact torus injector

International Nuclear Information System (INIS)

Onchi, T.; McColl, D.; Dreval, M.; Wolfe, S.; Xiao, C.; Hirose, A.

2014-01-01

A novel circuit for compact torus (CT) injector operated at high repetition rates has been developed. The core technology adopted in the present work is to charge a large storage capacitor bank and quickly charge the CT capacitor bank through a stack of insulated-gate bipolar transistors (IGBTs). A system consisting of IGBTs and slow banks for the repetitive operation has been developed and installed for each discharge circuit of the University of Saskatchewan Compact Torus Injector (USCTI). A repetition rate up to 1.7 Hz and a burst of 8 CTs have been achieved
Injerto óseo en bloque usando como donante torus mandibular. Reporte de caso

Directory of Open Access Journals (Sweden)

Oswaldo Cantillo Pallares

2014-01-01

Full Text Available Actualmente los materiales empleados para regeneración a través de injertos óseos están basados en compuestos sintéticos con propiedades en ocasiones poco predecibles para los pacientes. Los torus son exostosis óseas de etiología desconocida y pueden ser utilizados como injertos óseos con resultados clínicos exitosos. Así, el objetivo de este reporte de caso es describir la técnica quirúrgica de injerto óseo en bloque utilizando como donante torus mandibulares. Los resultados clínicos a 8 semanas postoperatorias evidenciaron tejidos en cicatrización y pocas molestias referidas por el paciente. Los injertos óseos provenientes de torus mandibulares son técnicas quirúrgicas de mediana complejidad que pueden ser empleados y permiten la obtención de resultados clínicos similares a los de otros materiales.
On the runaway instability of self-gravitating torus around black holes

International Nuclear Information System (INIS)

Font, Jose A; Montero, Pedro J; Shibata, Masaru

2010-01-01

Black holes surrounded by self-gravitating tori are astrophysical systems which may naturally form following the core collapse of a massive star or the merger of two neutron stars. We present here results from fully general relativistic numerical simulations of such systems in order to assess the influence of the torus self-gravity on the onset of the so-called runaway instability. This instability, which might drive the rapid accretion of the disk on shorter timescales than those required to power a relativistic fireball, potentially challenges current models of gamma-ray bursts. Our simulations indicate that the self-gravity of the torus does not actually favour the onset of the instability.
Vertical injection of compact torus into the STOR-M tokamak

International Nuclear Information System (INIS)

Liu, D.; Singh, A.K.; Hirose, A.; Xiao, C.

2005-01-01

Vertical compact torus injection into the STOR-M tokamak has been conducted with the University of Saskatchewan Compact Torus Injector (USCTI). The injector stayed at the horizontal position and the CT was bent by 90 deg. using a curved conducting drift tube. The curved drift tube did not have significant effects on the CT velocity. Furthermore, the curved drift tube did not change the magnetic field topology. Preliminary vertical CT injection experiments have been carried out on the STOR-M tokamak. CT injection induced prompt increase in the electron density and in the soft x-ray radiation level. Further modifications of the 90 deg. are underway to improve the CT parameters and to further study the effects of CT injection on the tokamak plasma parameters. (author)

Numerical study of the Columbia high-beta device: Torus-II

Energy Technology Data Exchange (ETDEWEB)

Izzo, R.

1981-01-01

The ionization, heating and subsequent long-time-scale behavior of the helium plasma in the Columbia fusion device, Torus-II, is studied. The purpose of this work is to perform numerical simulations while maintaining a high level of interaction with experimentalists. The device is operated as a toroidal z-pinch to prepare the gas for heating. This ionization of helium is studied using a zero-dimensional, two-fluid code. It is essentially an energy balance calculation that follows the development of the various charge states of the helium and any impurities (primarily silicon and oxygen) that are present. The code is an atomic physics model of Torus-II. In addition to ionization, we include three-body and radiative recombination processes.
Numerical study of the Columbia high-beta device: Torus-II

International Nuclear Information System (INIS)

Izzo, R.

1981-01-01

The ionization, heating and subsequent long-time-scale behavior of the helium plasma in the Columbia fusion device, Torus-II, is studied. The purpose of this work is to perform numerical simulations while maintaining a high level of interaction with experimentalists. The device is operated as a toroidal z-pinch to prepare the gas for heating. This ionization of helium is studied using a zero-dimensional, two-fluid code. It is essentially an energy balance calculation that follows the development of the various charge states of the helium and any impurities (primarily silicon and oxygen) that are present. The code is an atomic physics model of Torus-II. In addition to ionization, we include three-body and radiative recombination processes
THE ROLE OF THE ACCRETION DISK, DUST, AND JETS IN THE IR EMISSION OF LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI

Energy Technology Data Exchange (ETDEWEB)

Mason, R. E. [Gemini Observatory, Northern Operations Center, 670 N. A' ohoku Place, Hilo, HI 96720 (United States); Ramos Almeida, C. [Instituto de Astrofísica de Canarias, C/Vía Láctea, s/n, E-38205 La Laguna, Tenerife (Spain); Levenson, N. A. [Gemini Observatory, Southern Operations Center, c/o AURA, Casilla 603, La Serena (Chile); Nemmen, R. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Alonso-Herrero, A., E-mail: rmason@gemini.edu [Instituto de Física de Cantabria, CSIC-UC, Avenida de los Castros s/n, E-39005 Santander (Spain)

2013-11-10

We use recent high-resolution infrared (IR; 1-20 μm) photometry to examine the origin of the IR emission in low-luminosity active galactic nuclei (LLAGN). The data are compared with published model fits that describe the spectral energy distribution (SED) of LLAGN in terms of an advection-dominated accretion flow, truncated thin accretion disk, and jet. The truncated disk in these models is usually not luminous enough to explain the observed IR emission, and in all cases its spectral shape is much narrower than the broad IR peaks in the data. Synchrotron radiation from the jet appears to be important in very radio-loud nuclei, but the detection of strong silicate emission features in many objects indicates that dust must also contribute. We investigate this point by fitting the IR SED of NGC 3998 using dusty torus and optically thin (τ{sub mid-IR} ∼ 1) dust shell models. While more detailed modeling is necessary, these initial results suggest that dust may account for the nuclear mid-IR emission of many LLAGN.
Summary of calculations of dynamic response characteristics and design stress of the 1/5 scale PSE torus

International Nuclear Information System (INIS)

Arthur, D.

1977-01-01

The Lawrence Livermore Laboratory is currently involved in a 1/5 scale testing program on the Mark I BWR pressure suppression system. A key element of the test setup is a pressure vessel that is a 90 0 sector of a torus. Proper performance of the 90 0 torus depends on its structural integrity and structural dynamic characteristics. It must sustain the internal pressurization of the planned tests, and its dynamic response to the transient test loads should be minimal. If the structural vibrations are too great, interpretation of important load cell and pressure transducer data will be difficult. The purpose of the report is to bring together under one cover calculations pertaining to the structural dynamic characteristics and structural integrity of 90 0 torus. The report is divided into the following sections: (1) system description in which the torus and associated hardware are briefly described; (2) structural dynamics in which calculations of natural frequency and dynamic response are presented; and (3) structural integrity in which stress calculations for design purposes are presented; and an appendix which contains an LLL internal report comparing the expected load cell response for a three and four-point supported torus
Pseudomagic nuclei

International Nuclear Information System (INIS)

Scharff-Goldhaber, G.

1979-01-01

It was shown previously that, below a critical angular momentum, yrast bands of nonmagic nuclei are well described by the two-parameter variable moment of inertia model. Some striking exceptions to this rule are found in nuclei which have the same mass number as doubly magic nuclei but possess either one (or two) proton pairs beyond a magic number and one (or two) neutron hole pairs, or vice versa. Yrast bands in these pseudomagic nuclei resemble those in magic nuclei. 17 references
Five-dimensional gauge theory and compactification on a torus

NARCIS (Netherlands)

Haghighat, B.; Vandoren, S.J.G.

2011-01-01

We study five-dimensional minimally supersymmetric gauge theory compactified on a torus down to three dimensions, and its embedding into string/M-theory using geometric engineering. The moduli space on the Coulomb branch is hyperkaehler equipped with a metric with modular transformation properties.
Short interval expansion of Rényi entropy on torus

Energy Technology Data Exchange (ETDEWEB)

Chen, Bin [Department of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University,5 Yiheyuan Rd, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter,5 Yiheyuan Rd, Beijing 100871 (China); Center for High Energy Physics, Peking University,5 Yiheyuan Rd, Beijing 100871 (China); Wu, Jun-Bao [Theoretical Physics Division, Institute of High Energy Physics, Chinese Academy of Sciences,19B Yuquan Rd, Beijing 100049 (China); Theoretical Physics Center for Science Facilities, Chinese Academy of Sciences,19B Yuquan Rd, Beijing 100049 (China); Center for High Energy Physics, Peking University,5 Yiheyuan Rd, Beijing 100871 (China); Zhang, Jia-ju [Theoretical Physics Division, Institute of High Energy Physics, Chinese Academy of Sciences,19B Yuquan Rd, Beijing 100049 (China); Theoretical Physics Center for Science Facilities, Chinese Academy of Sciences,19B Yuquan Rd, Beijing 100049 (China)

2016-08-23

We investigate the short interval expansion of the Rényi entropy for two-dimensional conformal field theory (CFT) on a torus. We require the length of the interval ℓ to be small with respect to the spatial and temporal sizes of the torus. The operator product expansion of the twist operators allows us to compute the short interval expansion of the Rényi entropy at any temperature. In particular, we pay special attention to the large c CFTs dual to the AdS{sub 3} gravity and its cousins. At both low and high temperature limits, we read the Rényi entropies to order ℓ{sup 6}, and find good agreements with holographic results. Moreover, the expansion allows us to read 1/c contribution, which is hard to get by expanding the thermal density matrix. We generalize the study to the case with the chemical potential as well.
The incredible shrinking torus

International Nuclear Information System (INIS)

Fischler, W.; Susskind, L.

1997-01-01

Using M(atrix) theory, the dualities of toroidally compactified M-theory can be formulated as properties of super Yang Mills theories in various dimensions. We consider the cases of compactification on 1-, 2-, 3-, 4- and 5-dimensional tori. The dualities required by string theory lead to conjectures of remarkable symmetries and relations between field theories as well as extremely unusual dynamical properties. By studying the theories in the limit of vanishingly small tori, a wealth of information is obtained about strongly coupled fixed points of super Yang-Mills theory in various dimensions. Perhaps the most striking behavior, as noted by Rozali in this context, is the emergence of an additional dimension of space in the case of a 4-torus. (orig.)
Modular differential equations for torus one-point functions

International Nuclear Information System (INIS)

Gaberdiel, Matthias R; Lang, Samuel

2009-01-01

It is shown that in a rational conformal field theory every torus one-point function of a given highest weight state satisfies a modular differential equation. We derive and solve these differential equations explicitly for some Virasoro minimal models. In general, however, the resulting amplitudes do not seem to be expressible in terms of standard transcendental functions
Atomic force microscopy of torus-bearing pit membranes

Science.gov (United States)

Roland R. Dute; Thomas Elder

2011-01-01

Atomic force microscopy was used to compare the structures of dried, torus-bearing pit membranes from four woody species, three angiosperms and one gymnosperm. Tori of Osmanthus armatus are bipartite consisting of a pustular zone overlying parallel sets of microfibrils that form a peripheral corona. Microfibrils of the corona form radial spokes as they traverse the...
Exploration of spherical torus physics in the NSTX device

Science.gov (United States)

Ono, M.; Kaye, S. M.; Peng, Y.-K. M.; Barnes, G.; Blanchard, W.; Carter, M. D.; Chrzanowski, J.; Dudek, L.; Ewig, R.; Gates, D.; Hatcher, R. E.; Jarboe, T.; Jardin, S. C.; Johnson, D.; Kaita, R.; Kalish, M.; Kessel, C. E.; Kugel, H. W.; Maingi, R.; Majeski, R.; Manickam, J.; McCormack, B.; Menard, J.; Mueller, D.; Nelson, B. A.; Nelson, B. E.; Neumeyer, C.; Oliaro, G.; Paoletti, F.; Parsells, R.; Perry, E.; Pomphrey, N.; Ramakrishnan, S.; Raman, R.; Rewoldt, G.; Robinson, J.; Roquemore, A. L.; Ryan, P.; Sabbagh, S.; Swain, D.; Synakowski, E. J.; Viola, M.; Williams, M.; Wilson, J. R.; NSTX Team

2000-03-01

The National Spherical Torus Experiment (NSTX) is being built at Princeton Plasma Physics Laboratory to test the fusion physics principles for the spherical torus concept at the MA level. The NSTX nominal plasma parameters are R0 = 85 cm, a = 67 cm, R/a >= 1.26, Bt = 3 kG, Ip = 1 MA, q95 = 14, elongation κ The plasma heating/current drive tools are high harmonic fast wave (6 MW, 5 s), neutral beam injection (5 MW, 80 keV, 5 s) and coaxial helicity injection. Theoretical calculations predict that NSTX should provide exciting possibilities for exploring a number of important new physics regimes, including very high plasma β, naturally high plasma elongation, high bootstrap current fraction, absolute magnetic well and high pressure driven sheared flow. In addition, the NSTX programme plans to explore fully non-inductive plasma startup as well as a dispersive scrape-off layer for heat and particle flux handling.
Status of National Spherical Torus Experiment (NSTX)*

Science.gov (United States)

Ono, Masayuki

2001-10-01

The main aim of National Spherical Torus Experiment (NSTX) is to establish the fusion physics principles of the innovative spherical torus (ST) concept. The NSTX experimental facility has been operating reliably and its capabilities steadily improving. Due to relatively efficient ohmic current drive and benign halo current behavior, the plasma current was increased to 1.4 MA, which is well above the design value of 1 MA. The plasmas at 1 MA are now routinely heated by NBI to the average toroidal beta value of 20 percent range at 3 kG with electrons and ions in the 1-2 keV range. Even with the “L-mode” edge, the energy confinement time can well exceed the so-called L-mode (and even H-mode) scaling values. As a part of ST tool development, High Harmonic Fast Wave (HHFW) heating has demonstrated efficient electron heating with the central electron temperatures reaching 3.7 keV. HHFW induced H-modes have been also observed. For CHI (Coaxial Helicity Injection) non-inductive start-up, CHI discharges of up to 300 kA of toroidal current and 300 msec duration have been produced from zero current using = 25 kA of injected current. The poster presentation will also include the near term NSTX facility upgrade plan.
Analysis of 2D Torus and Hub Topologies of 100Mb/s Ethernet for the Whitney Commodity Computing Testbed

Science.gov (United States)

Pedretti, Kevin T.; Fineberg, Samuel A.; Kutler, Paul (Technical Monitor)

1997-01-01

A variety of different network technologies and topologies are currently being evaluated as part of the Whitney Project. This paper reports on the implementation and performance of a Fast Ethernet network configured in a 4x4 2D torus topology in a testbed cluster of 'commodity' Pentium Pro PCs. Several benchmarks were used for performance evaluation: an MPI point to point message passing benchmark, an MPI collective communication benchmark, and the NAS Parallel Benchmarks version 2.2 (NPB2). Our results show that for point to point communication on an unloaded network, the hub and 1 hop routes on the torus have about the same bandwidth and latency. However, the bandwidth decreases and the latency increases on the torus for each additional route hop. Collective communication benchmarks show that the torus provides roughly four times more aggregate bandwidth and eight times faster MPI barrier synchronizations than a hub based network for 16 processor systems. Finally, the SOAPBOX benchmarks, which simulate real-world CFD applications, generally demonstrated substantially better performance on the torus than on the hub. In the few cases the hub was faster, the difference was negligible. In total, our experimental results lead to the conclusion that for Fast Ethernet networks, the torus topology has better performance and scales better than a hub based network.
Effects of torus wall flexibility on forces in the Mark I Boiling Water Reactor Pressure Suppression System. Part I

International Nuclear Information System (INIS)

Martin, R.W.; McCauley, E.W.

1977-09-01

The authors investigated the effects of torus wall flexibility in the pressure suppression system of a Mark I boiling water reactor (BWR) when the torus wall is subjected to hydrodynamic loadings. Using hypothetical models, they examined these flexibility effects under two hydrodynamic loading conditions: (1) a steam relief valve (SRV) discharge pulse, and (2) a loss-of-coolant accident (LOCA) chugging pulse. In the analyses of these events they used a recently developed two-dimensional finite element computer code. Taking the basic geometry and dimensions of the Monticello Mark I BWR nuclear power plant (in Monticello, Minnesota, U.S.A.), they assessed the effects of flexibility in the torus wall by changing values of the inside-diameter-to-wall-thickness ratio. Varying the torus wall thickness (t) with respect to the inside diameter (D) of the torus, they assigned values to the ratio D/t ranging from 0 (infinitely rigid) to 600 (highly flexible). In the case of a modeled steam relief valve (SRV) discharge pulse, they found the peak vertical reaction force on the torus was reduced from that of a rigid wall response by a factor of 3 for the most highly flexible, plant-simulated wall (D/t = 600). The reduction factor for a modeled loss-of-coolant accident (LOCA) chugging pulse was shown to be 1.5. The two-dimensional analyses employed overestimate these reduction factors but have provided, as intended, definition of the effect of torus boundary stiffness. In the work planned for FY79, improved modeling of the structure and of the source is expected to result in factors more directly applicable to actual pressure suppression systems
ELMO Bumpy Torus

International Nuclear Information System (INIS)

1978-01-01

The ELMO Bumpy Torus (EBT) program of experiment, theory, and reactor studies has been a remarkably successful one. In the five years since EBT-I began operating, work has progressed from demonstrating macrostability to an increasingly detailed understanding of transport properties. Collisionless scaling (tau/sub E/ increases with temperature) has been observed and the magnitude of the energy confinement time is consistent with neoclassical theory. Experiments on EBT-S are now being conducted at the increased magnetic field levels and higher microwave power and frequency made possible by a 28-GHz gyrotron development program. Initial results confirm our assumptions of neoclassical scaling. In conjunction with the experimental advances, EBT theory now has a well-developed transport theory which models the physics which we now think to be important: for example, it yields negative ambipolar electric fields which are consistent with those measured. Stability calculations continue to predict stable equilibrium with β/sub ring/ approx. β/sub core/ approx. 20 to 40%
Summary of US compact torus experiments

International Nuclear Information System (INIS)

Hartman, C.W.

1981-01-01

During the past several years a rapid increase has occurred in compact torus (CT) research in the United States, reflecting renewed interest in this simplified reactor consequences of this configuration. This paper reviews early approaches to CT formation and results and summarizes present experimental studies. Recent experiments have demonstrated a number of macroscopic aspects of the CT, including the conditions under which a macroscopically stable CT can be formed and maintained. Scaling experiments and more detailed studies of plasma transport in progress are discussed along with experiments under construction
A comprehensive model of ion diffusion and charge exchange in the cold Io torus

Science.gov (United States)

Barbosa, D. D.; Moreno, M. A.

1988-01-01

A comprehensive analytic model of radial diffusion in the cold Io torus is developed. The model involves a generalized molecular cloud theory of SO2 and its dissociation fragments SO, O2, S, and O, which are formed at a relatively large rate by solar UV photodissociation of SO2. The key component of the new theory is SO, which can react with S(+) through a near-resonant charge exchange process that is exothermic. This provides a mechanism for the rapid depletion of singly ionized sulfur in the cold torus and can account for the large decrease in the total flux tube content inward of Io's orbit. The model is used to demonstrate quantitatively the effects of radial diffusion in a charge exchange environment that acts as a combined source and sink for ions in various charge states. A detailed quantitative explanation for the O(2+) component of the cold torus is given, and insight is derived into the workings of the so-called plasma 'ribbon'.
EDDYMULT: a computing system for solving eddy current problems in a multi-torus system

International Nuclear Information System (INIS)

Nakamura, Yukiharu; Ozeki, Takahisa

1989-03-01

A new computing system EDDYMULT based on the finite element circuit method has been developed to solve actual eddy current problems in a multi-torus system, which consists of many torus-conductors and various kinds of axisymmetric poloidal field coils. The EDDYMULT computing system can deal three-dimensionally with the modal decomposition of eddy current in a multi-torus system, the transient phenomena of eddy current distributions and the resultant magnetic field. Therefore, users can apply the computing system to the solution of the eddy current problems in a tokamak fusion device, such as the design of poloidal field coil power supplies, the mechanical stress design of the intensive electromagnetic loading on device components and the control analysis of plasma position. The present report gives a detailed description of the EDDYMULT system as an user's manual: 1) theory, 2) structure of the code system, 3) input description, 4) problem restrictions, 5) description of the subroutines, etc. (author)
THE SUBARCSECOND MID-INFRARED VIEW OF LOCAL ACTIVE GALACTIC NUCLEI. III. POLAR DUST EMISSION

International Nuclear Information System (INIS)

Asmus, D.; Hönig, S. F.; Gandhi, P.

2016-01-01

Recent mid-infrared (MIR) interferometric observations have shown that in a few active galactic nuclei (AGNs) the bulk of the infrared emission originates from the polar region above the putative torus, where only a little dust should be present. Here, we investigate whether such strong polar dust emission is common in AGNs. Out of 149 Seyferts in the MIR atlas of local AGNs, 21 show extended MIR emission on single-dish images. In 18 objects, the extended MIR emission aligns with the position angle (PA) of the system axis, established by [O iii], radio, polarization, and maser-based PA measurements. The relative amount of resolved MIR emission is at least 40% and scales with the [O iv] fluxes, implying a strong connection between the extended continuum and [O iv] emitters. These results together with the radio-quiet nature of the Seyferts support the scenario that the bulk of MIR emission is emitted by dust in the polar region and not by the torus, which would demand a new paradigm for the infrared emission structure in AGNs. The current low detection rate of polar dust in the AGNs of the MIR atlas is explained by the lack of sufficient high-quality MIR data and the requirements on the orientation, strength of narrow-line region, and distance of the AGNs. The James Webb Space Telescope will enable much deeper nuclear MIR studies with comparable angular resolution, allowing us to resolve the polar emission and surroundings in most of the nearby AGNs.
Recursive representation of the torus 1-point conformal block

Science.gov (United States)

Hadasz, Leszek; Jaskólski, Zbigniew; Suchanek, Paulina

2010-01-01

The recursive relation for the 1-point conformal block on a torus is derived and used to prove the identities between conformal blocks recently conjectured by Poghossian in [1]. As an illustration of the efficiency of the recurrence method the modular invariance of the 1-point Liouville correlation function is numerically analyzed.

Global solvability for involutive systems on the torus

Directory of Open Access Journals (Sweden)

Cleber de Medeira

2013-11-01

Full Text Available In this article, we consider a class of involutive systems of n smooth vector fields on the torus of dimension n+1. We prove that the global solvability of this class is related to an algebraic condition involving Liouville forms and the connectedness of all sublevel and superlevel sets of the primitive of a certain 1-form associated with the system.
Arithmetic functions in torus and tree networks

Science.gov (United States)

Bhanot, Gyan; Blumrich, Matthias A.; Chen, Dong; Gara, Alan G.; Giampapa, Mark E.; Heidelberger, Philip; Steinmacher-Burow, Burkhard D.; Vranas, Pavlos M.

2007-12-25

Methods and systems for performing arithmetic functions. In accordance with a first aspect of the invention, methods and apparatus are provided, working in conjunction of software algorithms and hardware implementation of class network routing, to achieve a very significant reduction in the time required for global arithmetic operation on the torus. Therefore, it leads to greater scalability of applications running on large parallel machines. The invention involves three steps in improving the efficiency and accuracy of global operations: (1) Ensuring, when necessary, that all the nodes do the global operation on the data in the same order and so obtain a unique answer, independent of roundoff error; (2) Using the topology of the torus to minimize the number of hops and the bidirectional capabilities of the network to reduce the number of time steps in the data transfer operation to an absolute minimum; and (3) Using class function routing to reduce latency in the data transfer. With the method of this invention, every single element is injected into the network only once and it will be stored and forwarded without any further software overhead. In accordance with a second aspect of the invention, methods and systems are provided to efficiently implement global arithmetic operations on a network that supports the global combining operations. The latency of doing such global operations are greatly reduced by using these methods.
Spin-k/2-spin-k/2 SU(2) two-point functions on the torus

International Nuclear Information System (INIS)

Kirsch, Ingo; Kucharski, Piotr

2012-11-01

We discuss a class of two-point functions on the torus of primary operators in the SU(2) Wess-Zumino-Witten model at integer level k. In particular, we construct an explicit expression for the current blocks of the spin-(k)/(2)-spin-(k)/(2) torus two-point functions for all k. We first examine the factorization limits of the proposed current blocks and test their monodromy properties. We then prove that the current blocks solve the corresponding Knizhnik-Zamolodchikov-like differential equations using the method of Mathur, Mukhi and Sen.
Spin-k/2-spin-k/2 SU(2) two-point functions on the torus

Energy Technology Data Exchange (ETDEWEB)

Kirsch, Ingo [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Gruppe Theorie; Kucharski, Piotr [Warsaw Univ. (Poland). Inst. of Theoretical Physics

2012-11-15

We discuss a class of two-point functions on the torus of primary operators in the SU(2) Wess-Zumino-Witten model at integer level k. In particular, we construct an explicit expression for the current blocks of the spin-(k)/(2)-spin-(k)/(2) torus two-point functions for all k. We first examine the factorization limits of the proposed current blocks and test their monodromy properties. We then prove that the current blocks solve the corresponding Knizhnik-Zamolodchikov-like differential equations using the method of Mathur, Mukhi and Sen.
Recent Progress on Spherical Torus Research

Energy Technology Data Exchange (ETDEWEB)

Ono, Masayuki [PPPL; Kaita, Robert [PPPL

2014-01-01

The spherical torus or spherical tokamak (ST) is a member of the tokamak family with its aspect ratio (A = R0/a) reduced to A ~ 1.5, well below the normal tokamak operating range of A ≥ 2.5. As the aspect ratio is reduced, the ideal tokamak beta β (radio of plasma to magnetic pressure) stability limit increases rapidly, approximately as β ~ 1/A. The plasma current it can sustain for a given edge safety factor q-95 also increases rapidly. Because of the above, as well as the natural elongation κ, which makes its plasma shape appear spherical, the ST configuration can yield exceptionally high tokamak performance in a compact geometry. Due to its compactness and high performance, the ST configuration has various near term applications, including a compact fusion neutron source with low tritium consumption, in addition to its longer term goal of attractive fusion energy power source. Since the start of the two megaampere class ST facilities in 2000, National Spherical Torus Experiment (NSTX) in the US and Mega Ampere Spherical Tokamak (MAST) in UK, active ST research has been conducted worldwide. More than sixteen ST research facilities operating during this period have achieved remarkable advances in all of fusion science areas, involving fundamental fusion energy science as well as innovation. These results suggest exciting future prospects for ST research both near term and longer term. The present paper reviews the scientific progress made by the worldwide ST research community during this new mega-ampere-ST era.
Torus type thermonuclear device

International Nuclear Information System (INIS)

Kitazawa, Hakaru; Saito, Ryusei.

1981-01-01

Purpose: To obtain toroidal coil supports structures capable of coping with the changes in the elasticity distribution due to thermal expansion and performing elastic support function corresponding to the distribution of stresses exerted on the toroidal coils, by providing elastic function to the inner circumference side of the coil support structures. Constitution: Support structures for supporting toroidal coils from above and below are formed at the torus inner circumference side thereof with ribs in contact with a central block and having elasticity coefficient corresponding to the distribution of stresses exerted on the toroidal coils, and the stresses exerted on the toroidal coils are elastically supported on the ribs. Accordingly, if the stress distribution varies due to the thermal expansion or the like, adequate supporting function can be obtained well-corresponding to such changes, whereby effective plasma confinement can be attained. (Moriyama, K.)
The ELMO Bumpy Torus: present and future

International Nuclear Information System (INIS)

Uckan, N.A.

1978-01-01

The ELMO Bumpy Torus (EBT) experiment at ORNL was designed to circumvent the MHD stability problem encountered in standard bumpy tori by using the ''minimum-B'' properties of annular high-beta, hot-electron plasmas formed by microwave heating. The EBT combines the attractive features of both mirrors and tokamaks. The feasibility of this combined system has been demonstrated successfully in the EBT-I experiment and discussed at greater length elsewhere. The present status of the EBT research activities at ORNL is described briefly
The Schwinger Model on the torus

International Nuclear Information System (INIS)

Azakov, S.

1996-08-01

The classical and quantum aspects of the Schwinger model on the torus are considered. First we find explicitly all zero modes of the Dirac operator in the topological sectors with nontrivial Chern index and its spectrum. In the second part we determine the regularized effective action and discuss the propagators related to it. Finally we calculate the gauge invariant averages of the fermion bilinears and correlation functions of currents and densities. We show that in the infinite volume limit the well-known result for the chiral condensate can be obtained and the clustering property can be established. (author). 23 refs
The mechanism of total disintegration of heavy nuclei by fast hadrons and nuclei

International Nuclear Information System (INIS)

Strugalska-Gola, E.; Strugalski, Z.

1997-01-01

The mechanism of the total disintegration of atomic nuclei by fast hadrons and nuclei is considered. The passage of energetic hadrons through layers of intranuclear matter, accompanied by emission of fast nucleons with kinetic energies from about 20 up to about 500 MeV from definite local small regions in the nuclei around projectile courses in them, allows one to explain simply the occurrence of the total destruction of nuclei involved in the collisions. Light nuclei may be totally disintegrated by fast hadrons and nuclei; heavier nuclei may be totally disintegrated only in central collisions of nuclei with similar mass numbers
Comparative study of poloidal field systems for the torus II experiment

International Nuclear Information System (INIS)

Farvaque, L.; Ghazal, S.; Leloup, C.; Pariente, M.; CEA Centre d'Etudes Nucleaires de Fontenay-aux-Roses, 92

1976-11-01

Three types of transformer for the TORUS II experiment are compared: a saturated iron core transformer with an entire magnetic circuit, an air core transformer and a saturated iron core transformer restricted to the central limb [fr
Differences in neurogenesis differentiate between core and shell regions of auditory nuclei in the turtle (Pelodiscus sinensis): evolutionary implications.

Science.gov (United States)

Zeng, Shao-Ju; Xi, Chao; Zhang, Xin-Wen; Zuo, Ming-Xue

2007-01-01

There is a clear core-versus-shell distinction in cytoarchitecture, electrophysiological properties and neural connections in the mesencephalic and diencephalic auditory nuclei of amniotes. Determining whether the embryogenesis of auditory nuclei shows a similar organization is helpful for further understanding the constituent organization and evolution of auditory nuclei. Therefore in the present study, we injected [(3)H]-thymidine into turtle embryos (Pelodiscus sinensis) at various stages of development. Upon hatching, [(3)H]-thymidine labeling was examined in both the core and shell auditory regions in the midbrain, diencephalon and dorsal ventricular ridge. Met-enkephalin and substance P immunohistochemistry was used to distinguish the core and shell regions. In the mesencephalic auditory nucleus, the occurrence of heavily labeled neurons in the nucleus centralis of the torus semicircularis reached its peak at embryonic day 9, one day later than the surrounding shell. In the diencephalic auditory nucleus, the production of heavily labeled neurons in the central region of the reuniens (Re) was highest at embryonic day (E) 8, one day later than that in the shell region of reuniens. In the region of the dorsal ventricular ridge that received inputs from the central region of Re, the appearance of heavily labeled neurons also reached a peak one day later than that in the area receiving inputs from the shell region of reuniens. Thus, there is a core-versus-shell organization of neuronal generation in reptilian auditory areas. Copyright (c) 2007 S. Karger AG, Basel.
Riemann-Hilbert treatment of Liouville theory on the torus: the general case

International Nuclear Information System (INIS)

Menotti, Pietro

2011-01-01

We extend the previous treatment of Liouville theory on the torus to the general case in which the distribution of charges is not necessarily symmetric. This requires the concept of Fuchsian differential equation on Riemann surfaces. We show through a group theoretic argument that the Heun parameter and a weight constant are sufficient to satisfy all monodromy conditions. We then apply the technique of differential equations on a Riemann surface to the two-point function on the torus in which one source is arbitrary and the other small. As a byproduct, we give in terms of quadratures the exact Green function on the square and on the rhombus with opening angle 2π/6 in the background of the field generated by an arbitrary charge.
On the location of the Io plasma torus: Voyager 1 observations

Directory of Open Access Journals (Sweden)

M. Volwerk

2018-06-01

Full Text Available The Voyager 1 outbound ultraviolet observations of the Io plasma torus are used to determine the location of the ansae, to obtain a third viewing angle of this structure in the Jovian magnetosphere. At an angle of −114° with respect to the Sun–Jupiter line, or a Jovian local time of 04:30 LT, the Voyager 1 data deliver a distance of 5.74±0.10 RJ for the approaching and 5.83±0.15 RJ for the receding ansa. Various periodicities in the radial distance, brightness and width of the ansae are seen with respect to system III longitude and Io phase angle. The torus ribbon feature does not appear in all ansa scans.
10D massive type IIA supergravities as the uplift of parabolic M2-brane torus bundles

Energy Technology Data Exchange (ETDEWEB)

Garcia del Moral, Maria Pilar [Universidad de Antofagasta (Chile). Dept. de Fisica; Restuccia, Alvaro [Universidad de Antofagasta (Chile). Dept. de Fisica; Universidad Simon Bolivar, Caracas (Venezuela, Bolivarian Republic of). Dept. de Fisica

2016-04-15

We remark that the two 10D massive deformations of the N = 2 maximal type IIA supergravity (Romans and HLW supergravity) are associated to the low energy limit of the uplift to 10D of M2-brane torus bundles with parabolic monodromy linearly and non-linearly realized respectively. Romans supergravity corresponds to M2-brane compactified on a twice-punctured torus bundle. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Conceptual design of the Purdue compact torus/passive liner fusion reactor

International Nuclear Information System (INIS)

Terry, W.K.

1981-01-01

This proposal describes a program for the conceptual development of a novel fusion reactor design, the Purdue Compact Torus/Passive Liner Reactor. The key features of the concept are described and a comparison is made with a conventional tokamak
Physics results from the National Spherical Torus Experiment

International Nuclear Information System (INIS)

Kaye, S.; Bell, M.

2000-01-01

The mission of the National Spherical Torus Experiment (NSTX) is to extend the understanding of toroidal physics to low aspect ratio (R/a ∼ 1.25) in low collisionality regimes. NSTX is designed to operate with up to 6 MW of High Harmonic Fast Wave (HHFW) heating and current drive, 5 MW of Neutral Beam Injection (NBI), and Co-Axial Helicity Injection (CHI) for non-inductive startup. Initial experiments focused on establishing conditions that will allow NSTX to achieve its aims of simultaneous high-β t and high-bootstrap current fraction, and to develop methods for non-inductive operation, which will be necessary for Spherical Torus power plants. Ohmic discharges with plasma currents up to 1 MA, stored energies up to 55 kJ, β t ∼ 10%, and a range of shapes and configurations were produced. Density limits in deuterium and helium reached 80% and 120% of the Greenwald limit respectively. Significant electron heating was observed with up to 2.3 MW of HHFW. Up to 270 kA of toroidal current for up to 200 msec was produced noninductively using CHI. Initial NBI experiments were carried out with up to two beam sources (3.2 MW). Plasmas with stored energies of up to 140 kJ and β t =21% were produced
Probing the clumpy winds of giant stars with high mass X-ray binaries

Science.gov (United States)

Grinberg, Victoria; Hell, Natalie; Hirsch, Maria; Garcia, Javier; Huenemoerder, David; Leutenegger, Maurice A.; Nowak, Michael; Pottschmidt, Katja; Schulz, Norbert S.; Sundqvists, Jon O.; Townsend, Richard D.; Wilms, Joern

2016-04-01

Line-driven winds from early type stars are structured, with small, overdense clumps embedded in tenuous hot gas. High mass X-ray binaries (HMXBs), systems where a neutron star or a black hole accretes from the line-driven stellar wind of an O/B-type companion, are ideal for studying such winds: the wind drives the accretion onto the compact object and thus the X-ray production. The radiation from close to the compact object is quasi-pointlike and effectively X-rays the wind.We used RXTE and Chandra-HETG observations of two of the brightest HMXBs, Cyg X-1 and Vela X-1, to decipher their wind structure. In Cyg X-1, we show that the orbital variability of absorption can be only explained by a clumpy wind model and constrain the porosity of the wind as well as the onion-like structure of the clumps. In Vela X-1 we show, using the newest reference energies for low ionization Si-lines obtained with LLNL’s EBIT-I, that the ionized phase of the circumstellar medium and the cold clumps have different velocities.
Matrix factorizations and homological mirror symmetry on the torus

International Nuclear Information System (INIS)

Knapp, Johanna; Omer, Harun

2007-01-01

We consider matrix factorizations and homological mirror symmetry on the torus T 2 using a Landau-Ginzburg description. We identify the basic matrix factorizations of the Landau-Ginzburg superpotential and compute the full spectrum taking into account the explicit dependence on bulk and boundary moduli. We verify homological mirror symmetry by comparing three-point functions in the A-model and the B-model
Perturbative construction of self-dual configurations on the torus

International Nuclear Information System (INIS)

Garcia Perez, M.; Gonzalez-Arroyo, A.; Pena, C.

2000-01-01

We develop a perturbative expansion which allows the construction of non-abelian self-dual SU(2) Yang-Mills field configurations on the four-dimensional torus with topological charge 1/2. The expansion is performed around the constant field strength abelian solutions found by 't Hooft. Next to leading order calculations are compared with numerical results obtained with lattice gauge theory techniques. (author)
High energy density fusing using the Compact Torus

International Nuclear Information System (INIS)

Hartman, C.W.

1989-01-01

My remarks are concerned with employing the Compact Torus magnetic field configuration to produce fusion energy. In particular, I would like to consider high energy density regimes where the pressures generated extend well beyond the strength of materials. Under such conditions, where nearby walls are vaporized and pushed aside each shot, the technological constraints are very different from usual magnetic fusion and may admit opportunities for an improved fusion reactor design. 5 refs., 3 figs

Beta II compact torus experiment plasma equilibrium and power balance

International Nuclear Information System (INIS)

Turner, W.C.; Goldenbaum, G.C.; Granneman, E.H.A.; Prono, D.S.; Hartman, C.W.; Taska, J.

1982-01-01

In this paper we follow up some of our earlier work that showed the compact torus (CT) plasma equilibrium produced by a magnetized coaxial plasma gun is nearly force free and that impurity radiation plays a dominant role in determining the decay time of plasma currents in present generation experiments
Plasma diagnostics in compact torus of UNICAMP (Campinas state university)

International Nuclear Information System (INIS)

Ueda, M; Doi, Y.; Aramaki, E.A.; Porto, P.; Berni, L.; Machida, M.

1989-08-01

This paper which describes experiments carried out in the Compact Torus of UNICAMP (TC-1) is divided into 3 parts: 1) summary of TC-1 characteristics and its operation mode; 2) description of diagnostics in use and ones to be installed, 3) recent experimental results using optical and electromagnetical diagnostics. (author)
Exotic nuclei

International Nuclear Information System (INIS)

Villari, A.C.C.

1990-01-01

The actual tendencies to study exotic nuclei; applications of exotic nuclei beams in material study and medicine; recent results obtained by GANIL and Berkeley Laboratories of measurements of binding energy and radii of light nuclei; the future experiences to be carry out in several international laboratories and; proposal of studies in Brazil using Pelletron-USP accelerator and the LINAC superconductor accelerator, in construction in the same laboratory, are presented. (M.C.K.)
Method to prevent ejecta from damaging the Compact Torus Accelerator driver of an inertial fusion energy power plant

International Nuclear Information System (INIS)

Mattingly, S.E.K.; Moir, R.W.

1992-01-01

Concern has been expressed about the conceptual design of fusion reactors using a Compact Torus Accelerator (CTA). A CTA accelerates a plasma torus toward a fusion target. When the torus nears the target, it is compressed and focused down to a small volume, creating a very high energy density and initiating a fusion micro explosion. The focusing cone is destroyed with each shot due to the stress from the passage of the torus as well as from the force of the explosion (1 800 MJ of yield, ∼0.5 Ton TNT equivalent). The focusing cone could be made of solidified Li 2 BeF 4 ; the same material used in liquid state to protect the reaction chamber from the micro explosion and to transport heat away to a power plant. The problem with this design is that when the focusing cone is shattered, the resulting small pieces of solid and liquid debris (ejecta) might be carded along by the expanding vapor of the explosion and might enter the CTA itself, causing damage and shortening the life of the CTA. The proposed solution for this possible problem is to bend the focusing cone so that the ejecta no longer have a clear path to the CTA. Calculations show that the plasma torus may be sent through a radius of curvature of less than 0.5 m just after the focusing cone, without significantly disturbing the plasma
The torus parametrization of quasiperiodic LI-classes

CERN Document Server

Baake, M; Pleasants, P A B

2002-01-01

The torus parametrization of quasiperiodic local isomorphism classes is introduced and used to determine the number of elements in such a class with special symmetries or inflation properties. The method is explained in an illustrative fashion for some widely used tiling classes with golden mean rescaling, namely for the Fibonacci chain (1D), the triangle and Penrose patterns (2D) and for Kramer's and Danzer's icosahedral tilings (3D). We obtain a rather complete picture of the orbit structure within these classes, but discuss also various general results.
Tightness of the Ising-Kac Model on the Two-Dimensional Torus

Science.gov (United States)

Hairer, Martin; Iberti, Massimo

2018-05-01

We consider the sequence of Gibbs measures of Ising models with Kac interaction defined on a periodic two-dimensional discrete torus near criticality. Using the convergence of the Glauber dynamic proven by Mourrat and Weber (Commun Pure Appl Math 70:717-812, 2017) and a method by Tsatsoulis and Weber employed in (arXiv:1609.08447 2016), we show tightness for the sequence of Gibbs measures of the Ising-Kac model near criticality and characterise the law of the limit as the Φ ^4_2 measure on the torus. Our result is very similar to the one obtained by Cassandro et al. (J Stat Phys 78(3):1131-1138, 1995) on Z^2, but our strategy takes advantage of the dynamic, instead of correlation inequalities. In particular, our result covers the whole critical regime and does not require the large temperature/large mass/small coupling assumption present in earlier results.
Advanced tokamak reactors based on the spherical torus (ATR/ST). Preliminary design considerations

International Nuclear Information System (INIS)

Miller, R.L.; Krakowski, R.A.; Bathke, C.G.; Copenhaver, C.; Schnurr, N.M.; Engelhardt, A.G.; Seed, T.J.; Zubrin, R.M.

1986-06-01

Preliminary design results relating to an advanced magnetic fusion reactor concept based on the high-beta, low-aspect-ratio, spherical-torus tokamak are summarized. The concept includes resistive (demountable) toroidal-field coils, magnetic-divertor impurity control, oscillating-field current drive, and a flowing liquid-metal breeding blanket. Results of parametric tradeoff studies, plasma engineering modeling, fusion-power-core mechanical design, neutronics analyses, and blanket thermalhydraulics studies are described. The approach, models, and interim results described here provide a basis for a more detailed design. Key issues quantified for the spherical-torus reactor center on the need for an efficient drive for this high-current (approx.40 MA) device as well as the economic desirability to increase the net electrical power from the nominal 500-MWe(net) value adopted for the baseline system. Although a direct extension of present tokamak scaling, the stablity and transport of this high-beta (approx.0.3) plasma is a key unknown that is resoluble only by experiment. The spherical torus generally provides a route to improved tokamak reactors as measured by considerably simplified coil technology in a configuration that allows a realistic magnetic divertor design, both leading to increased mass power density and reduced cost
Shutdown dose rates at ITER equatorial ports considering radiation cross-talk from torus cryopump lower port

Energy Technology Data Exchange (ETDEWEB)

Juárez, Rafael, E-mail: rjuarez@ind.uned.es [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain); Pampin, Raul [F4E, Torres Diagonal Litoral B3, Josep Pla 2, Barcelona 08019 (Spain); Levesy, Bruno [ITER Organization, 13115 Route de Vinon sur Verdon, St Paul Lez Durance (France); Moro, Fabio [ENEA, Via Enrico Fermi 45, Frascati, Rome (Italy); Suarez, Alejandro [ITER Organization, 13115 Route de Vinon sur Verdon, St Paul Lez Durance (France); Sanz, Javier [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain)

2015-11-15

Shutdown dose rates for planned maintenance purposes is an active research field in ITER. In this work the radiation (neutron and gamma) cross-talk between ports in the most conservative case foreseen in ITER is investigated: the presence of a torus cryopump lower port, mostly empty for pumping efficiency reasons. There will be six of those ports: #4, #6, #10, #12, #16 and #18. The equatorial ports placed above them will receive a significant amount of additional radiation affecting the shutdown dose rates during in situ maintenance activities inside the cryostat, and particularly in the port interspace area. In this study a general situation to all the equatorial ports placed above torus cryopump lower ports is considered: a generic diagnostics equatorial port placed above the torus cryopump lower port (LP#4). In terms of shutdown dose rates at equatorial port interspace after 10{sup 6} s of cooling time, 405 μSv/h has been obtained, of which 160 μSv/h (40%) are exclusively due to radiation cross-talk from a torus cryopump lower port. Equatorial port activation due to only “local neutrons” contributes 166 μSv/h at port interspace, showing that radiation cross-talk from such a lower port is a phenomenon comparable in magnitude to the neutron leakage though the equatorial port plug.
MID- AND FAR-INFRARED PROPERTIES OF A COMPLETE SAMPLE OF LOCAL ACTIVE GALACTIC NUCLEI

International Nuclear Information System (INIS)

Ichikawa, Kohei; Ueda, Yoshihiro; Terashima, Yuichi; Oyabu, Shinki; Gandhi, Poshak; Nakagawa, Takao; Matsuta, Keiko

2012-01-01

We investigate the mid- (MIR) to far-infrared (FIR) properties of a nearly complete sample of local active galactic nuclei (AGNs) detected in the Swift/Burst Alert Telescope (BAT) all-sky hard X-ray (14-195 keV) survey, based on the cross correlation with the AKARI infrared survey catalogs complemented by those with Infrared Astronomical Satellite and Wide-field Infrared Survey Explorer. Out of 135 non-blazer AGNs in the Swift/BAT nine-month catalog, we obtain the MIR photometric data for 128 sources either in the 9, 12, 18, 22, and/or 25 μm band. We find good correlation between their hard X-ray and MIR luminosities over three orders of magnitude (42 λ (9, 18 μm) < 45), which is tighter than that with the FIR luminosities at 90 μm. This suggests that thermal emission from hot dusts irradiated by the AGN emission dominate the MIR fluxes. Both X-ray unabsorbed and absorbed AGNs follow the same correlation, implying isotropic infrared emission, as expected in clumpy dust tori rather than homogeneous ones. We find excess signals around 9 μm in the averaged infrared spectral energy distribution from heavy obscured 'new type' AGNs with small scattering fractions in the X-ray spectra. This could be attributed to the polycyclic aromatic hydrocarbon emission feature, suggesting that their host galaxies have strong starburst activities.
Recent results in the Los Alamos compact torus program

International Nuclear Information System (INIS)

Tuszewski, M.; Armstrong, W.T.; Barnes, C.W.

1983-01-01

A Compact Toroid is a toroidal magnetic-plasma-containment geometry in which no conductors or vacuum-chamber walls pass through the hole in the torus. Two types of compact toroids are studied experimentally and theoretically at Los Alamos: spheromaks that are oblate in shape and contain both toroidal and poloidal magnetic fields, and field-reversed configurations (FRC) that are very prolate and contain poloidal field only
Nuclei transmutation by collisions with fast hadrons and nuclei

International Nuclear Information System (INIS)

Strugalski, Z.; Strugalska-Gola, E.; Drzymala, A.

1998-01-01

Atomic nuclei change their mass- and charge-numbers if bombarded by fast hadrons and nuclei; the transmutation appears as a complicated process. It proceeds in a definite way - through a few stages or phases. Adequate identification of the nucleons and light nuclear fragments emitted and evaporated in a hadron-nucleus or nucleus-nucleus collisions and in the collision-induced intranuclear reactions allows one to estimate quantitatively the nuclei transmutations in the various stages (phases) of the process
The Coulomb gas representation of critical RSOS models on the sphere and the torus

International Nuclear Information System (INIS)

Foda, O.; Nienhuis, B.

1989-01-01

We derive the Coulomb gas formulation of the c<1 discrete unitary series, on the sphere and the torus, starting from the corresponding regime-III RSOS models on a square lattice with appropriate topology. We clarify the origin of the background charge, the screening charges, and the choice of operator representations in a correlation function. In the scaling limit, we obtain a bosonic action coupled to the background curvature in addition to topological terms that vanish on the Riemann sphere. Its Virasoro algebra has the central charge expected on the basis of comparing conformal dimensions. As an application, we derive general expressions for the correlation functions on the torus. (orig.)
The Coulomb gas representation of critical RSOS models on the sphere and the torus

Energy Technology Data Exchange (ETDEWEB)

Foda, O. (Rijksuniversiteit Utrecht (Netherlands). Inst. voor Theoretische Fysica); Nienhuis, B. (Rijksuniversiteit Leiden (Netherlands). Inst. Lorentz voor Theoretische Natuurkunde)

1989-10-02

We derive the Coulomb gas formulation of the c<1 discrete unitary series, on the sphere and the torus, starting from the corresponding regime-III RSOS models on a square lattice with appropriate topology. We clarify the origin of the background charge, the screening charges, and the choice of operator representations in a correlation function. In the scaling limit, we obtain a bosonic action coupled to the background curvature in addition to topological terms that vanish on the Riemann sphere. Its Virasoro algebra has the central charge expected on the basis of comparing conformal dimensions. As an application, we derive general expressions for the correlation functions on the torus. (orig.).
Pair correlations in nuclei

International Nuclear Information System (INIS)

Shimizu, Yoshifumi

2009-01-01

Except for the closed shell nuclei, almost all nuclei are in the superconducting state at their ground states. This well-known pair correlation in nuclei causes various interesting phenomena. It is especially to be noted that the pair correlation becomes weak in the excited states of nuclei with high angular momentum, which leads to the pair phase transition to the normal state in the high spin limit. On the other hand, the pair correlation becomes stronger in the nuclei with lower nucleon density than in those with normal density. In the region of neutron halo or skin state of unstable nuclei, this phenomenon is expected to be further enhanced to be observed compared to the ground state of stable nuclei. An overview of those interesting aspects caused via the pair correlation is presented here in the sections titled 'pair correlations in ground states', pair correlations in high spin states' and 'pair correlations in unstable nuclei' focusing on the high spin state. (S. Funahashi)
Compact torus compression of microwaves

International Nuclear Information System (INIS)

Hewett, D.W.; Langdon, A.B.

1985-01-01

The possibility that a compact torus (CT) might be accelerated to large velocities has been suggested by Hartman and Hammer. If this is feasible one application of these moving CTs might be to compress microwaves. The proposed mechanism is that a coaxial vacuum region in front of a CT is prefilled with a number of normal electromagnetic modes on which the CT impinges. A crucial assumption of this proposal is that the CT excludes the microwaves and therefore compresses them. Should the microwaves penetrate the CT, compression efficiency is diminished and significant CT heating results. MFE applications in the same parameters regime have found electromagnetic radiation capable of penetrating, heating, and driving currents. We report here a cursory investigation of rf penetration using a 1-D version of a direct implicit PIC code
Acceleration of a compact torus

International Nuclear Information System (INIS)

Hartmann, C.W.; Eddleman, J.L.; Hammer, J.H.; Kusse, B.

1987-01-01

The authors report the first results of a study of acceleration of spheromak-type compact toruses in the RACE experiment (plasma Ring ACceleration Experiment). The RACE apparatus consists of (1) a magnetized, coaxial plasma gun 50 cm long, 35 cm OD, 20 cm ID, (2) 600 cm long coaxial acceleration electrodes 50 cm OD, 20 cm ID, (3) a 250 kJ electrolytic capacitor bank to drive the gun solenoid for initial magnetization, (4) a 200 kJ gun bank, (5) a 260 kJ accelerator bank, and (6) magnetic probes and other diagnostics, and vacuum apparatus. To outer acceleration electrode is an extension, at larger OD, of the gun outer electrode, and the inner acceleration electrode is supported and fed by a coaxial insert in the gun center electrode as shown
Coulomb thermal properties and stability of the Io plasma torus

Science.gov (United States)

Barbosa, D. D.; Coroniti, F. V.; Eviatar, A.

1983-01-01

Coulomb collisional energy exchange rates are computed for a model of the Io plasma torus consisting of newly created pickup ions, a background of thermally degraded intermediary ions, and a population of cooler electrons. The electrons are collisionally heated by both the pickup ions and background ions and are cooled by electron impact excitation of plasma ions which radiate in the EUV. It is found that a relative concentration of S III pickup ions forbidden S III/electrons = 0.1 with a temperature of 340 eV can deliver energy to the electrons at a rate of 3 x 10 to the -13th erg/cu cm per sec, sufficient to power the EUV emissions in the Io torus. The model predicts a background ion temperature Ti of about 53 eV and an electron temperature Te of about 5.5 eV on the basis of steady-state energy balance relations at Coulomb rates. The model also predicts electron temperature fluctuations at the 30 percent level on a time scale of less than 11 hours, consistent with recent observations of this phenomenon.
X-ray production experiments on the RACE Compact Torus Accelerator

International Nuclear Information System (INIS)

Hammer, J.H.; Eddleman, J.L.; Hartman, C.W.; McLean, H.S.; Molvik, A.W.; Gee, M.

1989-12-01

The Purpose of the Compact Torus Accelerator (CTA) program at LLNL is to prove the principle of a unique accelerator concept based on magnetically confined compact torus (CT) plasma rings and to study applications. Successful achievement of these goals could lead to a high power-density driver for many applications including an intense x-ray source for nuclear weapons effects simulation and an inertial fusion driver. Fusion applications and a description of the CTA concept are included in a companion paper at this conference. This paper will describe the initial experiments on soft x-ray production conducted on the plasma Ring ACcelerator Experiment (RACE) and compare the results to modeling studies. The experiments on CT stagnation and soft x-ray production were conducted with unfocused rings as a first of CT dynamics and the physics of x-ray production. The x-ray fluences observed are consistent with expectations based on calculations employing a radiation-hydrodynamics code. We conclude with a diffusion of future x-ray production studies that can be conducted on RACE and a possible multi-megajoule upgrade
Engineering feasibility of tight aspect ratio Tokamak (spherical torus) reactors

International Nuclear Information System (INIS)

Peng, Y-K.M.; Hicks, J.B.

1990-01-01

Engineering solutions are identified and analyzed for key high-power-density components of tight aspect ratio tokamak reactors (spherical torus reactors). The potentially extreme divertor heat loads can be reduced to about 3 MW/m 2 in expanded divertors using coils inside the demountable toroidal field coils. Given the long and narrow divertor channels, gaseous divertor targets become possible, which eliminate sputtering and increase the divertor life. The unshielded centre conductor post (CCP) of the toroidal field coil can be made of a single dispersion strengthened copper conductor cooled by high-velocity pressurized water to maintain acceptable copper temperature and strength. Damage and activation of the CCP at a neutron fluence of 10 MW-a/m 2 are also tolerable. Annual replacement of the centre post, the divertor assemblies and the blanket can be accomplished with vertical access for all torus components, which are modularized to reduce size and weight. The technical requirements of these solutions are shown to be comparable with, if not less demanding than, those estimated for conventional tokamak reactors. (author)
From heavy nuclei to super-heavy nuclei

International Nuclear Information System (INIS)

Theisen, Ch.

2003-01-01

The existence of super-heavy nuclei has been predicted nearly fifty years ago. Due to the strong coulomb repulsion, the stabilisation of these nuclei is possible only through shell effects. The reasons for this fragile stability, as well as the theoretical predictions concerning the position of the island of stability are presented in the first part of this lecture. In the second part, experiments and experimental techniques which have been used to synthesize or search for super-heavy elements are described. Spectroscopic studies performed in very heavy elements are presented in the following section. We close this lecture with techniques that are currently being developed in order to reach the superheavy island and to study the structure of very-heavy nuclei. (author)

Torus II. Technical description of the design proposal

International Nuclear Information System (INIS)

Aymar, R.; Deck, C.; Deschamps, P.; Lafon, D.; Leloup, C.; Pariente, M.; Renaud, C.; Sledziewski, Z.; Torossian, A.

1976-06-01

A new Tokamak device, called TORUS II, is proposed to be built inside the EURATOM-CEA Association. This is a large machine: I=1.7MA; B=30kGs; R=1.8m; a=75cm, designed to be a successor to TFR and to follow the lines of research already initiated in the present TFR programme, i.e. on plasma heating, on impurities, on energy confinement and scaling laws, providing to JET a very efficient backing. This part of the report provides a technical description of the main components of the basic machine, according to the state of design reached in June 1976. Every subsystem whose assembly forms the basic machine is the subject of one section: vacuum vessel, toroidal field coils, poloidal field system, mechanical structures, monitoring, control and data acquisition, and power supplies. The first part in each section attempts to summarize the solution that was retained, pointing out the problems to be solved and the choice made. No contribution takes into account the problems of installation and buildings and the time schedule which is given is only concerned with the simplest solution. By way, contributions are given which show the state of development of the peripheral systems envisaged for TORUS II, mainly: additional heating, control of impurities and plasma diagnostics [fr
Studies of exotic nuclei

International Nuclear Information System (INIS)

Angelique, J.C.; Orr, N.A.

1997-01-01

The study of the nuclei far off stability valley is of much interest for testing the nuclear models established for the stable nuclei but also for astrophysics to understand the nucleosynthesis. Experiments aim to measure the mass and lifetime, to build the decay schemes and also to study the structure and the properties of these nuclei. The radioactive beam group focused its research on light neutron-rich nuclei having a halo neutron structure. Mass measurements in N ∼ Z nuclei namely in A ∼ 60-80 proton-rich nuclei, important for understanding the rp process, are mentioned, as well as in nuclei in the 100 Sn region. In the newly obtained 26 O and 28 O nuclei the lifetimes, the probabilities of emission of one for more neutrons were determined. The data analysis has permitted to determine also for the first time the lifetimes of 27,29 F and 30 Ne. Studies of nuclei in the 100 Sn region, near the proton drip line in the ground and isomeric states are now under way. The spectroscopy (energy levels, gamma emissions, etc.) of the neutron-rich nuclei produced by the 36 S fragmentation has been carried out in 31 Ne, 17 B and 29 F. Studies by Coulomb excitation of the 2 + excited states and associated probability B (E2) in O, Ne, Ni and Zn are now analysed
Mechanical design assessments of structural components and auxiliaries of the Joint European Torus

International Nuclear Information System (INIS)

Sonnerup, L.

1986-01-01

The general design of the Joint European Torus (JET) is briefly described. The loads on its major structural components, at normal operation, and in cases of plasma instability and/or disruption, are discussed. The way these components have been assessed and optimised in relation to their loads is presented. A short account of mechanical design problems of auxiliary equipment is given. Finally, the state of operation of JET and its implications for the mechanical design is summarized. The mechanically most important components of the JET device are the support structure of the toroidal magnet, the vacuum vessel, the coils of the magnets and the pedestals supporting the weight of the torus. These components all participate in resisting and transmitting the primary forces during operation. (orig.)
Two intervals Rényi entanglement entropy of compact free boson on torus

International Nuclear Information System (INIS)

Liu, Feihu; Liu, Xiao

2016-01-01

We compute the N=2 Rényi entanglement entropy of two intervals at equal time in a circle, for the theory of a 2D compact complex free scalar at finite temperature. This is carried out by performing functional integral on a genus 3 ramified cover of the torus, wherein the quantum part of the integral is captured by the four point function of twist fields on the worldsheet torus, and the classical piece is given by summing over winding modes of the genus 3 surface onto the target space torus. The final result is given in terms of a product of theta functions and certain multi-dimensional theta functions. We demonstrate the T-duality invariance of the result. We also study its low temperature limit. In the case in which the size of the intervals and of their separation are much smaller than the whole system, our result is in exact agreement with the known result for two intervals on an infinite system at zero temperature http://dx.doi.org/10.1088/1742-5468/2009/11/P11001. In the case in which the separation between the two intervals is much smaller than the interval length, the leading thermal corrections take the same universal form as proposed in http://dx.doi.org/10.1103/PhysRevLett.112.171603, http://dx.doi.org/10.1103/PhysRevD.91.105013 for Rényi entanglement entropy of a single interval.
Ultrasoft x-ray imaging system for the National Spherical Torus Experiment

Science.gov (United States)

Stutman, D.; Finkenthal, M.; Soukhanovskii, V.; May, M. J.; Moos, H. W.; Kaita, R.

1999-01-01

A spectrally resolved ultrasoft x-ray imaging system, consisting of arrays of high resolution (the National Spherical Torus Experiment. Initially, three poloidal arrays of diodes filtered for C 1s-np emission will be implemented for fast tomographic imaging of the colder start-up plasmas. Later on, mirrors tuned to the C Lyα emission will be added in order to enable the arrays to "see" the periphery through the hot core and to study magnetohydrodynamic activity and impurity transport in this region. We also discuss possible core diagnostics, based on tomographic imaging of the Lyα emission from the plume of recombined, low Z impurity ions left by neutral beams or fueling pellets. The arrays can also be used for radiated power measurements and to map the distribution of high Z impurities injected for transport studies. The performance of the proposed system is illustrated with results from test channels on the CDX-U spherical torus at Princeton Plasma Physics Laboratory.
Numerical study of spherical Torus MHD equilibrium configuration

International Nuclear Information System (INIS)

Cheng Faying; Dong Jiaqi; Wang Aike

2003-01-01

Tokamak equilibrium code SWEQU has been modified so that it can be used for the MHD equilibrium study of low aspect ratio device. Evolution of plasma configuration in start-up phase and double-null divertor configuration in steady-state phase has been simulated using the modified code. Results show that the new code can be used not only to obtain the equilibrium configuration of spherical Torus in steady-state phase, but also to simulate the evolution of plasma in the start-up phase
Piotron at SIN - a large superconducting double torus spectrometer

International Nuclear Information System (INIS)

Horvath, I.; Vecsey, G.; Zellweger, J.

1981-01-01

A test facility for radiation therapy with negative /pi/-mesons was constructed in Switzerland. The facility is a large double torus spectrometer similar to the Stanford design. For variation of stopping depth different momenta are selected by variation of the magnetic field. Superconducting ac magnets are necessary for tumor scanning and represent a major part of such a facility. Main design features and performance are reported. 10 refs
Development of concentric equipotential surfaces in bumpy torus plasma

International Nuclear Information System (INIS)

Takasugi, Keiichi; Iguchi, Harukazu; Fujiwara, Masami; Ikegami, Hideo

1983-01-01

Radial profiles of the plasma space potential are measured in Nagoya Bumpy Torus (NBT-1) by the use of a heavy ion beam probe. Asymmetric potential profiles owing to toroidal drift are observed in high pressure operation (C-mode). As the pressure is decreased, toroidal plasma is effectively heated (T-mode), poloidal precessional frequency overcomes the electron collision frequency and the equipotential surfaces becomes concentric inside the hot electron ring. (author)
Hopf bifurcation and chaos from torus breakdown in voltage-mode controlled DC drive systems

International Nuclear Information System (INIS)

Dai Dong; Ma Xikui; Zhang Bo; Tse, Chi K.

2009-01-01

Period-doubling bifurcation and its route to chaos have been thoroughly investigated in voltage-mode and current-mode controlled DC motor drives under simple proportional control. In this paper, the phenomena of Hopf bifurcation and chaos from torus breakdown in a voltage-mode controlled DC drive system is reported. It has been shown that Hopf bifurcation may occur when the DC drive system adopts a more practical proportional-integral control. The phenomena of period-adding and phase-locking are also observed after the Hopf bifurcation. Furthermore, it is shown that the stable torus can breakdown and chaos emerges afterwards. The work presented in this paper provides more complete information about the dynamical behaviors of DC drive systems.
The asymptotic hadron spectrum, anti-nuclei, hyper-nuclei and quark phase

International Nuclear Information System (INIS)

Glendenning, N.K.

1978-01-01

The only hope of determining the hadronic spectrum in the high mass region is through a study of matter produced in very high energy nuclear collisions. Along the way, exotic nuclei, i.e., anti-nuclei and hyper-nuclei may be produced in appreciable numbers, and the detection of a quark phase may be possible. (orig.) [de
Calibration of neutron detectors on the Joint European Torus.

Science.gov (United States)

Batistoni, Paola; Popovichev, S; Conroy, S; Lengar, I; Čufar, A; Abhangi, M; Snoj, L; Horton, L

2017-10-01

The present paper describes the findings of the calibration of the neutron yield monitors on the Joint European Torus (JET) performed in 2013 using a 252 Cf source deployed inside the torus by the remote handling system, with particular regard to the calibration of fission chambers which provide the time resolved neutron yield from JET plasmas. The experimental data obtained in toroidal, radial, and vertical scans are presented. These data are first analysed following an analytical approach adopted in the previous neutron calibrations at JET. In this way, a calibration function for the volumetric plasma source is derived which allows us to understand the importance of the different plasma regions and of different spatial profiles of neutron emissivity on fission chamber response. Neutronics analyses have also been performed to calculate the correction factors needed to derive the plasma calibration factors taking into account the different energy spectrum and angular emission distribution of the calibrating (point) 252 Cf source, the discrete positions compared to the plasma volumetric source, and the calibration circumstances. All correction factors are presented and discussed. We discuss also the lessons learnt which are the basis for the on-going 14 MeV neutron calibration at JET and for ITER.
Exposición espontánea de un torus palatino de la línea media

Directory of Open Access Journals (Sweden)

Gustavo Sinisterra

2013-03-01

Full Text Available Introducción. El torus, o rodete, palatino es una alteración ósea benigna que puede generar molestias en la fonación y en la deglución. Cuando su crecimiento o exposición persistente producen síntomas molestos, debe ser resecado quirúrgicamente. Presentación del caso. Se trata de una paciente de 82 años de edad, que consultó por una lesión ulcerativa de un año de evolución, que producía dolor, halitosis y molestia a la deglución. En el examen físico de la cavidad oral, se observó una prominencia de consistencia dura en la línea media, con perforación y ulceración de la mucosa palatina en su porción lateral posterior izquierda. Se consideraron los diagnósticos de torus palatino, osteoma, granuloma piógeno y neoplasia de tejidos blandos. Se decidió resecarla quirúrgicamente y hacer el estudio histopatológico. La evolución clínica fue satisfactoria, con resolución completa un mes después de la cirugía. En el estudio de histopatología se observó hiperostosis ósea con inflamación crónica de los tejidos blandos e hiperplasia simple de la mucosa, que corresponden a un torus palatino. Discusión. Se reporta un inusual caso de exposición espontánea de un torus palatino que ocupaba casi toda la bóveda palatina, se describe su resección quirúrgica y se informan los hallazgos de histopatología. En la revisión bibliográfica realizada, no se encontró un reporte previo de exposición espontánea de torus palatino. doi: http://dx.doi.org/10.7705/biomedica.v33i1.1480
Studies of accelerated compact toruses

International Nuclear Information System (INIS)

Hartman, C.W.; Eddleman, J.; Hammer, J.H.

1983-01-01

In an earlier publication we considered acceleration of plasma rings (Compact Torus). Several possible accelerator configurations were suggested and the possibility of focusing the accelerated rings was discussed. In this paper we consider one scheme, acceleration of a ring between coaxial electrodes by a B/sub theta/ field as in a coaxial rail-gun. If the electrodes are conical, a ring accelerated towards the apex of the cone undergoes self-similar compression (focusing) during acceleration. Because the allowable acceleration force, F/sub a/ = kappaU/sub m//R where (kappa - 2 , the accelerating distance for conical electrodes is considerably shortened over that required for coaxial electrodes. In either case, however, since the accelerating flux can expand as the ring moves, most of the accelerating field energy can be converted into kinetic energy of the ring leading to high efficiency
Level structures in Yb nuclei far from stable nuclei

International Nuclear Information System (INIS)

Hashizume, Akira

1982-01-01

Applying n-γ, γ-γ coincidence techniques, the excited levels in 158 Yb and in 157 Yb nuclei were studied. Stress is placed ona neutron detection technique to assign (HI,xn) reactions which produce the nuclei far from β stability line. (author)
Using a 2D Model of the Io Plasma Torus to Investigate the Effects of Density Variations on the Morphology and Intensity of the Io Footprint

Science.gov (United States)

Payan, A. P.; Rajendar, A.; Paty, C. S.; Bonfond, B.; Crary, F.

2012-12-01

Io is the primary source of plasma in the Jovian magnetosphere, continuously releasing approximately 1 ton/s of SO2 from volcanic eruptions. The interaction of Io with Jupiter's magnetosphere is strongly influenced by the density structure of the resulting plasma torus and the position of Io relative to the center of the torus [Bonfond et al. 2008]. This unusual interaction produces a complex auroral feature on Jupiter's ionosphere known as the Io footprint. Hubble Space Telescope (HST) observations of Jupiter's far-UV aurora during spring 2007 showed an increased number of isolated auroral blobs along with a continuous expansion of Jupiter's main auroral oval over a few months. These blobs were associated with several large injections of hot plasma between 9 and 27 Jovian radii. These events coincided with a large volcanic eruption of the Tvashtar Paterae on Io, as observed by the New Horizons spacecraft [Spencer et al., 2007]. This, in turn, may have resulted in a significant increase in the plasma torus density. Besides, on June 7th, 2007, the Io footprint momentarily became so faint that it disappeared under a diffuse patch of emission remaining from an injection blob [Bonfond et al., 2012]. The goal of the present study is to examine the relationship between the increased density of the plasma torus and the dimming of the Io footprint. We implement a 2D model of the Io plasma torus that treats the variable-density torus as being composed of discrete layers of uniform density. As the co-rotating plasma in the plasma torus impinges on Io, Alfvén waves are launched at a pushback angle obtained from Gurnett and Goertz [1981]. The waves propagate inside the plasma torus through reflection and refraction at density discontinuities where they lose some of their initial energy. Using the above model, we can track the Alfvén wave fronts in the plasma torus and determine the longitude at which they exit the torus along with the corresponding remaining energy. Since
Legendrian and transverse cables of positive torus knots

DEFF Research Database (Denmark)

Etnyre, John; LaFountain, Douglas; Tosun, Bülent

2012-01-01

Thurston-Bennequin invariant is arbitrarily far from maximal. We also exhibit Legendrian knots requiring arbitrarily many stabilizations before they become Legendrian isotopic. Similar new phenomena are observed for transverse knots. To achieve these results we define and study "partially thickenable" tori......In this paper we classify Legendrian and transverse knots in the knot types obtained from positive torus knots by cabling. This classification allows us to demonstrate several new phenomena. Specifically, we show there are knot types that have non-destabilizable Legendrian representatives whose...
Mechanical design assessments of structural components and auxiliaries of the Joint European Torus

International Nuclear Information System (INIS)

Sonnerup, L.

1985-01-01

The general design of the Joint European Torus (JET) is briefly described. The loads on its major structural components, at normal operation, and in cases of plasma instability and/or disruption, are discussed. The way these components have been assessed and optimised in relation to their loads is presented. A short account of mechanical design problems of auxiliary equipment is given. Finally, the state of operation of JET and its implications for the mechanical design at the time of the conference will be summarized. The mechanically most important components of the JET device are the support structure of the toroidal magnet, th vacuum vessel, the coils of the magnets and the pedestals supporting the weight of the torus. These components all participate in resisting and transmitting the primary forces during operation. (orig.)
MID-INFRARED SELECTION OF ACTIVE GALACTIC NUCLEI WITH THE WIDE-FIELD INFRARED SURVEY EXPLORER. II. PROPERTIES OF WISE-SELECTED ACTIVE GALACTIC NUCLEI IN THE NDWFS BOÖTES FIELD

International Nuclear Information System (INIS)

Assef, R. J.; Stern, D.; Eisenhardt, P. R. M.; Tsai, C.-W.; Kochanek, C. S.; Blain, A. W.; Brodwin, M.; Brown, M. J. I.; Donoso, E.; Jarrett, T. H.; Yan, L.; Jannuzi, B. T.; Stanford, S. A.; Wu, J.

2013-01-01

Stern et al. presented a study of Wide-field Infrared Survey Explorer (WISE) selection of active galactic nuclei (AGNs) in the 2 deg 2 COSMOS field, finding that a simple criterion W1-W2 ≥ 0.8 provides a highly reliable and complete AGN sample for W2 2 NOAO Deep Wide-Field Survey Boötes field which also has considerably deeper WISE observations than the COSMOS field, and find that this simple color cut significantly loses reliability at fainter fluxes. We define a modified selection criterion combining the W1–W2 color and the W2 magnitude to provide highly reliable or highly complete AGN samples for fainter WISE sources. In particular, we define a color-magnitude cut that finds 130 ± 4 deg –2 AGN candidates for W2 AGN ∼ 3 × 10 44 erg s –1 , 29% ± 7% of AGNs are observed as Type 1, while at ∼4 × 10 45 erg s –1 the fraction is 64% ± 13%. The distribution of obscuration values suggests that dust in the torus is present as both a diffuse medium and in optically thick clouds
Automatic path-planning for a multilink articulated boom within the torus of a fusion reactor

International Nuclear Information System (INIS)

Smidt, D.

1986-08-01

For in-torus maintenance of fusion machines a manipulator is conveyed to the working area by a multilink-transporter, also called 'articulated boom'. Systems of this type have in general four to five links and move in the midplane of the torus. They are kinematically redundant and have a very restricted working space. In this paper automatic methods for the collision free approach of any position of the final joint within the reach of the transporter are presented, including insertion and removal. By automatic teach-in with the CAD-simulation a table of safe configurations can be generated and supplemented by a fine-positioning algorithm. (orig.) [de
Braid group and anyons on an annulus and a torus

International Nuclear Information System (INIS)

Hatsugai, Y.; Kohmoto, M.; Wu Yongshi

1992-01-01

We present an examination of anyons on a cylinder (or annulus) starting from a braid group analysis. The rule for putting anyons on a lattice has to be modified when the periodic boundary condition is imposed on one direction. In contrast to the annulus, one extra restriction is needed for the cylinder geometry to recover its symmetry. The mean-field (MF) treatment is found to be good until level crossing occurs, and to be better if one starts from the hard-core boson rather than fermion. We also present a construction of anyons on a torus starting from a braid group analysis. The rules of Wen, Dagotto and Fradkin for putting anyons on a torus are reproduced and supplemented. The representation of the braid group is characterized by the anyon statistics θ and the magnetic fluxes Φ x and Φ y threading through the holes. It is shown that the anyon system has a smaller period in Φ x and Φ y than the natural period 1. We perform numerical calculations to investigate the spectral flow and find interesting features in understanding the Fractional Quantum Hall (FQH) effect. (orig.)

An FPGA-based torus communication network

Energy Technology Data Exchange (ETDEWEB)

Pivanti, Marcello; Schifano, Sebastiano Fabio [INFN, Ferrara (Italy); Ferrara Univ. (Italy); Simma, Hubert [DESY, Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC

2011-02-15

We describe the design and FPGA implementation of a 3D torus network (TNW) to provide nearest-neighbor communications between commodity multi-core processors. The aim of this project is to build up tightly interconnected and scalable parallel systems for scientific computing. The design includes the VHDL code to implement on latest FPGA devices a network processor, which can be accessed by the CPU through a PCIe interface and which controls the external PHYs of the physical links. Moreover, a Linux driver and a library implementing custom communication APIs are provided. The TNW has been successfully integrated in two recent parallel machine projects, QPACE and AuroraScience. We describe some details of the porting of the TNW for the AuroraScience system and report performance results. (orig.)
An FPGA-based torus communication network

International Nuclear Information System (INIS)

Pivanti, Marcello; Schifano, Sebastiano Fabio; Simma, Hubert

2011-02-01

We describe the design and FPGA implementation of a 3D torus network (TNW) to provide nearest-neighbor communications between commodity multi-core processors. The aim of this project is to build up tightly interconnected and scalable parallel systems for scientific computing. The design includes the VHDL code to implement on latest FPGA devices a network processor, which can be accessed by the CPU through a PCIe interface and which controls the external PHYs of the physical links. Moreover, a Linux driver and a library implementing custom communication APIs are provided. The TNW has been successfully integrated in two recent parallel machine projects, QPACE and AuroraScience. We describe some details of the porting of the TNW for the AuroraScience system and report performance results. (orig.)
Two dimensional critical models on a torus

International Nuclear Information System (INIS)

Saleur, H.; Di Francesco, P.

1987-01-01

After the general developments of conformal invariance in two dimensions, it was realized that the study of critical models in finite geometries, in addition to the practical information it could provide through finite size scaling, was also of great conceptual interest. The simplest example is the case of the torus, a genus 1 surface which is thus not conformally equivalent to the plane. This geometry appears quite frequently in lattice calculations for systems with periodic boundary conditions, and is also very natural from the point of view of string theory. We will discuss briefly in these notes the main results obtained so far in this simple case
Observational Constraints on a Pluto Torus of Circumsolar Neutral Gas

Science.gov (United States)

Hill, M. E.; Kollmann, P.; McNutt, R. L., Jr.; Smith, H. T.; Bagenal, F.; Brown, L. E.; Elliott, H. A.; Haggerty, D. K.; Horanyi, M.; Krimigis, S. M.; Kusterer, M. B.; Lisse, C. M.; McComas, D. J.; Piquette, M. R.; Sidrow, E. J.; Strobel, D. F.; Szalay, J.; Vandegriff, J. D.; Zirnstein, E.; Ennico Smith, K.; Olkin, C.; Weaver, H. A., Jr.; Young, L. A.; Stern, S. A.

2015-12-01

We present the concept of a neutral gas torus surrounding the Sun, aligned with Pluto's orbit, and place observational constraints based primarily on comparison of New Horizons (NH) measurements with a 3-D Monte Carlo model adapted from analogous satellite tori surrounding Saturn and Jupiter. Such a torus, or perhaps partial torus, should result from neutral N2 escaping from Pluto's exosphere. Unlike other more massive planets closer to the Sun, neutrals escape Pluto readily owing, e.g., to the high thermal speed relative to the escape velocity. Importantly, escaped neutrals have a long lifetime due to the great distance from the Sun, ~100 years for photoionization of N2 and ~180 years for photoionization of N, which results from disassociated N2. Despite the lengthy 248-year orbit, these long e-folding lifetimes may allow an enhanced neutral population to form an extended gas cloud that modifies the N2 spatial profile near Pluto. These neutrals are not directly observable by NH but once ionized N2+ or N+ are picked up by the solar wind, reaching ~50 keV, making these pickup ions (PUIs) detectable by NH's Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument. PEPSSI observations analyzed to date may constrain the N2 density; the remaining ~95% of the encounter data, scheduled for downlink in August along with similarly anticipated data from the Solar Wind Around Pluto (SWAP) experiment, should help determine the Pluto outgassing rates. Measurements from SWAP include the solar wind speed, a quantity that greatly enhances PUI studies by enabling us to directly account for the PUI distribution's sensitive dependence on plasma speed. Note that anomalous cosmic ray Si observed at Voyager is overabundant by a factor of ~3000 relative to interstellar composition. This might be related to "outer source" PUIs, but the fact that N2 and Si are indistinguishable in many instruments could mean that N2 is actually driving this apparent Si discrepancy.
Lagrange multiplier and Wess-Zumino variable as extra dimensions in the torus universe

Science.gov (United States)

Nejad, Salman Abarghouei; Dehghani, Mehdi; Monemzadeh, Majid

2018-01-01

We study the effect of the simplest geometry which is imposed via the topology of the universe by gauging non-relativistic particle model on torus and 3-torus with the help of symplectic formalism of constrained systems. Also, we obtain generators of gauge transformations for gauged models. Extracting corresponding Poisson structure of existed constraints, we show the effect of the shape of the universe on canonical structure of phase-spaces of models and suggest some phenomenology to prove the topology of the universe and probable non-commutative structure of the space. In addition, we show that the number of extra dimensions in the phase-spaces of gauged embedded models are exactly two. Moreover, in classical form, we talk over modification of Newton's second law in order to study the origin of the terms appeared in the gauged theory.
Characteristics and performance of a superconducting bumpy-torus magnet facility for plasma research

Science.gov (United States)

Roth, J. R.; Holmes, A. D.; Keller, T. A.; Krawczonek, W. M.

1973-01-01

The NASA Lewis bumpy-torus facility consists of 12 superconducting coils, each 19 cm i.d. and capable of 3.0 T on its axis. The coils are equally spaced around a toroidal array with a major diameter of 1.52 m; they are mounted with the major axis of the torus vertical in a single vacuum tank 2.6 m in diameter. Tests of the facility mapped out its magnetic, cryogenic, vacuum, mechanical, and electrical performance. The design value of the maximum magnetic field on the magnetic axis, 3.0 T, was reached and exceeded. A maximum magnetic field of 3.23 T was held for a period of 60 minutes. When the coils were charged to a maximum magnetic field of 3.35 T, the coil system went normal without apparent damage or degradation of performance.
K-bar-mesic nuclei

International Nuclear Information System (INIS)

Dote, Akinobu; Akaishi, Yoshinori; Yamazaki, Toshimitsu

2005-01-01

New nuclei 'K-bar-Mesic Nuclei' having the strangeness are described. At first it is shown that the strongly attractive nature of K-bar N interaction is reasoned inductively from consideration of the relation between Kaonic hydrogen atom and Λ (1405) which is an excited state of hyperon Λ. The K-bar N interactions are reviewed and summarized into three categories: 1. Phenomenological approach with density dependent K-bar N interaction (DD), relativistic mean field (RMF) approach, and hybrid of them (RMF+DD). 2. Boson exchange model. 3. Chiral SU(3) theory. The investigation of some light K-bar-nuclei by Akaishi and Yamazaki using phenomenological K-bar N interaction is explained in detail. Studies by antisymmetrized molecular dynamics (AMD) approach are also presented. From these theoretical researches, the following feature of K-bar-mesic nuclei are revealed: 1) Ground state is discrete and bound by 100 MeV or more. 2) Density is very high in side the K-bar-mesic nuclei. 3) Strange structures develop which are not seen in ordinary nuclei. Finally some recent experiments to explore K-bar-mesic nuclei are reviewed. (S. Funahashi)
Elmo Bumpy Torus proof of principle, Phase II: Title 1 report. Volume IX. Support structure

International Nuclear Information System (INIS)

Conlee, J.L.

1982-01-01

The EBT-P support structure provides structural support for the 36 mirror coil magnets, magnet protection system, the toroidal vessel, and much of the device ancillary equipment. The structure is comprised of a primary support and a superstructure. The primary support is a reinforced concrete ring located directly inboard of the torus and is supported by nine columns. The toroidal vessel and the mirror coil magnets are cantilevered from the ring with the centerline of the torus located eight feet above the floor. The superstructure is an aluminum truss structure that rests on the concrete ring. The superstructure provides support for the device ancillary equipment. Engineering drawings of the support structure are given
Direct torus venting analysis for Chinshan BWR-4 plant with MARK-I containment

Energy Technology Data Exchange (ETDEWEB)

Yuann, Yng-Ruey, E-mail: ryyuann@iner.gov.tw

2017-03-15

Highlights: • Study the effectiveness of Direct Torus Venting System (DTVS) during extended SBO of 24 h for Chinshan MARK-I plant. • Containment response is analyzed by GOTHIC based on boundary conditions from RETRAN calculation. • Analyses are performed with and without DTVS, respectively. • Suppression pool is sub-divided and thermal stratification is observed. - Abstract: The Chinshan plant, owned by Taiwan Power Company, has twin units of BWR-4 reactor and MARK-I containment. Both units have been operating at rated core thermal power of 1840 MWt. The existing Direct Torus Venting System (DTVS) is the main system used for venting the containment during the extended station blackout event. The purpose of this paper is to study the effects of the DTVS venting on the response of the containment pressure and temperature. The reactor is depressurized by manually opening the safety relief valves (SRVs) during the SBO, which causes the mass and energy to be discharged into and heat up the suppression pool. The RETRAN model is used to calculate the Nuclear Steam Supply System (NSSS) response and generate the SRV blowdown conditions, including SRV pressure, enthalpy, and mass flow rate. These conditions are then used as the time-dependent boundary conditions for the GOTHIC code to calculate the containment pressure and temperature response. The DTVS model is established in the GOTHIC model based on the venting size, venting piping loss, venting initiation time, and venting source. The lumped volume model, 1-D coarse-mesh model, and 3-D coarse-mesh model are considered in the torus volume. The calculation is first done without DTVS venting to establish a reference basis. Then a case with DTVS available is performed. Comparison of the two cases shows that the existing DTVS design is effective in mitigating the severity of the containment pressure and temperature transients. The results also show that the 1-D coarse-mesh model may not be appropriate since a
Space Propulsion via Spherical Torus Fusion Reactor

International Nuclear Information System (INIS)

Williams, Craig H.; Juhasz, Albert J.; Borowski, Stanley K.; Dudzinski, Leonard A.

2003-01-01

A conceptual vehicle design enabling fast outer solar system travel was produced predicated on a small aspect ratio spherical torus nuclear fusion reactor. Analysis revealed that the vehicle could deliver a 108 mt crew habitat payload to Saturn rendezvous in 204 days, with an initial mass in low Earth orbit of 1630 mt. Engineering conceptual design, analysis, and assessment were performed on all major systems including nuclear fusion reactor, magnetic nozzle, power conversion, fast wave plasma heating, fuel pellet injector, startup/re-start fission reactor and battery, and other systems. Detailed fusion reactor design included analysis of plasma characteristics, power balance and utilization, first wall, toroidal field coils, heat transfer, and neutron/X-ray radiation
Gamow-Teller decay of T = 1 nuclei to odd-odd N = Z nuclei

Energy Technology Data Exchange (ETDEWEB)

Lisetskiy, A F [National Superconducting Cyclotron Laboratory, MSU, East Lansing, MI 48824 (United States); Gelberg, A [Institute for Nuclear Physics, University of Cologne, 50937 Cologne (Germany); Institute of Physical and Chemical Reasearch (RIKEN), Wako, 351-0198 (Japan); Brentano, P von [Institute for Nuclear Physics, University of Cologne, 50937 Cologne (Germany)

2005-01-01

Transition strengths of Gamow-Teller decay of T{sub z} = {+-}1 nuclei to N = Z odd-odd nuclei have been calculated in a two-nucleon approximation for spherical and deformed nuclei. The results obtained for the latter are quite close to the values obtained by full-space shell-model calculations and to the experiment.
Bifurcation of synchronous oscillations into torus in a system of two reciprocally inhibitory silicon neurons: Experimental observation and modeling

International Nuclear Information System (INIS)

Bondarenko, Vladimir E.; Cymbalyuk, Gennady S.; Patel, Girish; DeWeerth, Stephen P.; Calabrese, Ronald L.

2004-01-01

Oscillatory activity in the central nervous system is associated with various functions, like motor control, memory formation, binding, and attention. Quasiperiodic oscillations are rarely discussed in the neurophysiological literature yet they may play a role in the nervous system both during normal function and disease. Here we use a physical system and a model to explore scenarios for how quasiperiodic oscillations might arise in neuronal networks. An oscillatory system of two mutually inhibitory neuronal units is a ubiquitous network module found in nervous systems and is called a half-center oscillator. Previously we created a half-center oscillator of two identical oscillatory silicon (analog Very Large Scale Integration) neurons and developed a mathematical model describing its dynamics. In the mathematical model, we have shown that an in-phase limit cycle becomes unstable through a subcritical torus bifurcation. However, the existence of this torus bifurcation in experimental silicon two-neuron system was not rigorously demonstrated or investigated. Here we demonstrate the torus predicted by the model for the silicon implementation of a half-center oscillator using complex time series analysis, including bifurcation diagrams, mapping techniques, correlation functions, amplitude spectra, and correlation dimensions, and we investigate how the properties of the quasiperiodic oscillations depend on the strengths of coupling between the silicon neurons. The potential advantages and disadvantages of quasiperiodic oscillations (torus) for biological neural systems and artificial neural networks are discussed
Experimental and simulation of split semi-torus key in PVC foam core to improve the debonding resistance of composite sandwich panel

Science.gov (United States)

Juliyana, M.; Santhana Krishnan, R.

2018-02-01

The sandwich composite panels consisting of facesheet and core material are used as a primary structural member for aerospace, civil and marine areas due to its high stiffness to weight ratio. But the debonding nature of facesheet from the foam core under shear loading conditions leads to failure of the composite structure. To inhibit the debonding, an innovative methodology of introducing semi-torus key is used in the present study. The polyvinyl chloride foam core(PVC) is grooved and filled with semi-torus shaped chopped strand prepregs which are sandwiched between alternate layers of woven roven(WR) and chopped strand mat(CSM) skins by vacuum infusion process. The sandwich panel manufactured with semi-torus keys is evaluated regarding experimental and numerical simulations under shear loading conditions. The present innovative concept delays the debonding between face-sheet and foam core with enhancement the shear load carrying capability as the initial stiffness is higher than the conventional model. Also, the shear behaviour of the proposed concept is in good agreement with experimental results. The split semi-torus keys sustain the shear failure resulting in resistance to debonding capability.
A program to develop advanced EBT [ELMO Bumpy Torus] concepts and international collaboration on the Bumpy Torus concept: Final report

International Nuclear Information System (INIS)

1987-01-01

This project was undertaken to develop innovative concepts for improving the performance of ELMO Bumpy Torus devices in those aspects of plasma confinement that are particularly relevant to an eventual EBT reactor concept. These include effective magnetic utilization using Andreoletti coils, enhanced confinement using positive ambipolar potentials, and attractive divertor concepts that are compatible with formation and maintenance of ELMO rings. Each of the three major objectives was achieved and, except for the divertor studies, documented for publication and presentation at major scientific meetings. This report provides a brief recapitulation of the major results achieved in the form of a collection of those publications, together with this Introduction
Indirect evidences for a gas/dust torus along the Phobos orbit

International Nuclear Information System (INIS)

Dubinin, E.M.; Lundin, R.; Pissarenko, N.F.; Barabash, S.V.; Zakharov, A.V.; Koskinen, H.; Schwingenshuh, K.; Yeroshenko, Ye.G.

1990-01-01

Observations from the PHOBOS-2 space-craft of plasma and magnetic field effects in the solar wind near Mars suggest that a neutral gas (dust?)torus/ring resides along the orbit of the Martian satellite Phobos. Magnetic cavities (strong decreases of the magnetic field strength) coincident with strong plasma density increases (up to a factor of ten) are observed during the first elliptic transition orbits when the spacecraft approached the Phobos orbits. The characteristic transverse dimension of the structures along the spacecraft orbit is in the range 100-1,000 km. Torus effects also have characteristics similar to the formation of a bow shock with increases of plasma density and ion temperature, and a characteristic deflection of the ion flow. This suggests a rather strong interaction between the solar wind plasma and plasma near Phobos orbit. The interaction appears quite similar to that of the solar wind with a comet. The outgassing of matter from Phobos (and Deimos) is also suggested by plasma observations in the wake/tail of the Martian satellites. Altogether, the authors observations imply that a neutral gas cloud - possibly also associated with a faint dust ring - exists along the Phobos orbit
Submillimeter and far-infrared line observations of M17 SW - A clumpy molecular cloud penetrated by ultraviolet radiation

Science.gov (United States)

Stutzki, J.; Genzel, R.; Harris, A. I.; Stacey, G. J.; Jaffe, D. T.

1988-01-01

Millimeter, submillimeter, and far-IR spectroscopic observations of the M17 SW star formation region are reported. Strong forbidden C II 158 micron and CO J = 7 - 6 line emission arises in an H II region/molecular cloud interface of several pc thickness. Weaker forbidden C II emission appears to be extended over 15 pc throughout the molecular cloud. CO J = 14 - 13 and forbidden O I 145 micron spectra indicate high temperatures and densities for both molecular and atomic gas in the interface. The results require the molecular cloud near the interface to be clumpy or filamentary. The extended forbidden C II emission throughout the molecular cloud has a level around 20 times higher than expected from a single molecular cloud interface exposed to an ultraviolet radiation field typical of the solar neighborhood. The high gas temperature of molecular material in the UV-illuminated interface region suggests that CO self-shielding and heating of CO by photoelectrons are important.
Dust inflated accretion disc as the origin of the broad line region in active galactic nuclei

Science.gov (United States)

Baskin, Alexei; Laor, Ari

2018-02-01

The broad line region (BLR) in active galactic nuclei (AGNs) is composed of dense gas (˜1011 cm-3) on sub-pc scale, which absorbs about 30 per cent of the ionizing continuum. The outer size of the BLR is likely set by dust sublimation, and its density by the incident radiation pressure compression (RPC). But, what is the origin of this gas, and what sets its covering factor (CF)? Czerny & Hryniewicz (2011) suggested that the BLR is a failed dusty wind from the outer accretion disc. We explore the expected dust properties, and the implied BLR structure. We find that graphite grains sublimate only at T ≃ 2000 K at the predicted density of ˜1011 cm-3, and therefore large graphite grains (≥0.3 μm) survive down to the observed size of the BLR, RBLR. The dust opacity in the accretion disc atmosphere is ˜50 times larger than previously assumed, and leads to an inflated torus-like structure, with a predicted peak height at RBLR. The illuminated surface of this torus-like structure is a natural place for the BLR. The BLR CF is mostly set by the gas metallicity, the radiative accretion efficiency, a dynamic configuration and ablation by the incident optical-UV continuum. This model predicts that the BLR should extend inwards of RBLR to the disc radius where the surface temperature is ≃2000 K, which occurs at Rin ≃ 0.18RBLR. The value of Rin can be tested by reverberation mapping of the higher ionization lines, predicted by RPC to peak well inside RBLR. The dust inflated disc scenario can also be tested based on the predicted response of RBLR and the CF to changes in the AGN luminosity and accretion rate.
Pairing correlations in nuclei

International Nuclear Information System (INIS)

Baba, C.V.K.

1988-01-01

There are many similarities between the properties of nucleons in nuclei and electrons in metals. In addition to the properties explainable in terms of independent particle motion, there are many important co-operative effects suggesting correlated motion. Pairing correlation which leads to superconductivity in metals and several important properties in nuclei , is an exmple of such correlations. An attempt has been made to review the effects of pairing correlations in nuclei. Recent indications of reduction in pairing correlations at high angular momenta is discussed. A comparision between pairing correlations in the cases of nuclei and electrons in metals is attempted. (author). 20 refs., 10 figs
CPRF/ZTH front-end torus design and fabrication status

International Nuclear Information System (INIS)

Ballard, E.O.; Baker, C.; Gomez, T.; Prince, P.P.; Smith, R.L.

1989-01-01

Design of the ZTH front-end torus has been completed for a new generation Reversed Field Pinch (RFP) machine to be assembled at Los Alamos National Laboratory during FY 92. The Confinement Physics Research Facility (CPRF) houses the ZTH front-end. The ZTH torus consists of an Inconel 625 vacuum vessel supported by an external electrically conducting 304L stainless steel shell. Interspace support rings support the vacuum vessel to the shell and also provide accurate radial support for the interspace electrical diagnostics. The shell also supports 48 toroidal field coils that are mounted to the shell's external surface. The shell consists of an explosion bonded stainless steel-copper composite with water-cooling tube assemblies attached to the outer surface. The 0.135-in. thick copper is on the inside surface of the shell, and provides an electrically conducting path with the required electrical time constant of 50 ms. The shell plate will be formed to the required toroidal configuration, after which the poloidal and toroidal flanges will be welded to the structure and machined. The Inconel vacuum vessel consists of bellows segments, armor support rings, and diagnostic stations welded together to form the complete vacuum vessel assembly. The necessity for accurate positioning of the vacuum vessel within the shell requires that the shell and vacuum vessel be fabricated with major diameter tolerances within 0.050-in. true position of the nominal diameters of 188.0-in. and 188.820-in., respectively. 7 figs
Edge fluctuations in the MST [Madison Symmetric Torus] reversed field pinch

International Nuclear Information System (INIS)

Almagri, A.; Assadi, S.; Beckstead, J.; Chartas, G.; Crocker, N.; Den Hartog, D.; Dexter, R.; Hokin, S.; Holly, D.; Nilles, E.; Prager, S.; Rempel, T.; Sarff, J.; Scime, E.; Shen, W.; Spragins, C.; Sprott, J.; Starr, G.; Stoneking, M.; Watts, C.

1990-10-01

Edge magnetic and electrostatic fluctuations are measured in the Madison Symmetric Torus (MST) reversed field pinch. At low frequency ( e > p e /p e where φ and p e are the fluctuating potential and pressure, respectively). From measurements of the fluctuating density, temperature, and potential we infer that the electrostatic fluctuation induced transport of particles and energy can be substantial. 13 refs., 11 figs

Final report on the LLNL compact torus acceleration project

International Nuclear Information System (INIS)

Eddleman, J.; Hammer, J.; Hartman, C.; McLean, H.; Molvik, A.

1995-01-01

In this report, we summarize recent work at LLNL on the compact torus (CT) acceleration project. The CT accelerator is a novel technique for projecting plasmas to high velocities and reaching high energy density states. The accelerator exploits magnetic confinement in the CT to stably transport plasma over large distances and to directed kinetic energies large in comparison with the CT internal and magnetic energy. Applications range from heating and fueling magnetic fusion devices, generation of intense pulses of x-rays or neutrons for weapons effects and high energy-density fusion concepts
Remote handling of JET in-torus components. A practical experience

International Nuclear Information System (INIS)

Mills, S.; Brade, R.; Edwards, P.

2000-01-01

This paper summarises the experiences gained from the extensive handling of JET components inside the torus. The problems involved with handling components not designed to be remotely handled and the methods used to overcome them are described and discussed with specific examples from recent JET remote operations. The method employed for remotely producing structural TIG welds is explained. The problems of dextrous manipulation in an inverted attitude are discussed and the methods of amelioration are described
Neoclassical transport associated with collisionless detrapping in a bumpy torus

International Nuclear Information System (INIS)

Hastings, D.E.

1983-10-01

In the two collisionality nonresonant regime in a bumpy torus the transitional particles can make a large contribution to neoclassical transport. This contribution can be moderated by the toroidally induced radial drift which causes transitional particles to detrap and retrap in the mirror sectors. This effect leads to diffusion coefficients which are linear in the collision frequency and scale with the inverse aspect ratio instead of the more usual square of the inverse aspect ratio. (author)
Sloshing of water in torus pressure-suppression pool of boiling water reactors under earthquake ground motions

International Nuclear Information System (INIS)

Aslam, M.; Godden, W.G.; Scalise, D.T.

1978-08-01

This report presents an analytical and experimental investigation into the sloshing of water in torus tanks under horizontal earthquake ground motions. This study was motivated because of the use of torus tanks for pressure-suppression pools in Boiling Water Reactors. Such a pressure-suppression pool would typically have 80 ft and 140 ft inside and outside diameters, a 30 ft diameter section, and a water depth of 15 ft. A general finite element analysis was developed for all axisymmetric tanks and a computer program was written to obtain time-history plots of sloshing displacements of water and dynamic pressures. Tests were carried out on a 1/60th scale model under sinusoidal as well as simulated earthquake ground motions. Tests and analytical results regarding natural frequencies, surface water displacements, and dynamic pressures were compared and a good agreement was found within the range of displacements studied. The computer program gave satisfactory results within a maximum range of sloshing displacements in the full-size prototype of 30 in. which is greater than the value obtained under the full intensity of the El Centro earthquake (N-S component 1940). The range of linear behavior was studied experimentally by subjecting the torus model to increasing intensities of the El Centro earthquake
Equilibrium and stability of high-beta plasma in Modified Bumpy Torus (MBT)

International Nuclear Information System (INIS)

Todoroki, J.; Shiina, S.; Saito, K.; Osanai, Y.; Nogi, Y.; Gesso, H.; Yagi, I.; Yokoyama, K.; Yoshimura, H.; Nihon Univ., Tokyo. Atomic Energy Research Inst.)

1977-01-01

The equilibrium and stability properties of the plasma in Modified Bumpy Torus, which is an asymmetric system with closed magnetic lines of force, is reported. For small beta value, the growth rate of m=1 mode instability in MBT can be smaller than that of Scyllac configuration. The results of 1/4 toroidal sector experiment are reported. (author)
Nuclei and quantum worlds

International Nuclear Information System (INIS)

Chomaz, Ph.

2000-01-01

This document gathers the slides and their commentaries that have been presented at the conference 'physics and fundamental questions' by P. Chomaz. The author reviews the different quantum aspects of nuclei: tunnel effect, symmetries, magic numbers, wave functions, size, shapes and deformations. The author shows that nuclei are quantum objects of great complexity, their structures are not yet well understood and the study of exotic nuclei will continue bringing valuable information
Divertor heat flux mitigation in the National Spherical Torus Experimenta)

Science.gov (United States)

Soukhanovskii, V. A.; Maingi, R.; Gates, D. A.; Menard, J. E.; Paul, S. F.; Raman, R.; Roquemore, A. L.; Bell, M. G.; Bell, R. E.; Boedo, J. A.; Bush, C. E.; Kaita, R.; Kugel, H. W.; Leblanc, B. P.; Mueller, D.; NSTX Team

2009-02-01

Steady-state handling of divertor heat flux is a critical issue for both ITER and spherical torus-based devices with compact high power density divertors. Significant reduction of heat flux to the divertor plate has been achieved simultaneously with favorable core and pedestal confinement and stability properties in a highly shaped lower single null configuration in the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 2000] using high magnetic flux expansion at the divertor strike point and the radiative divertor technique. A partial detachment of the outer strike point was achieved with divertor deuterium injection leading to peak flux reduction from 4-6MWm-2to0.5-2MWm-2 in small-ELM 0.8-1.0MA, 4-6MW neutral beam injection-heated H-mode discharges. A self-consistent picture of the outer strike point partial detachment was evident from divertor heat flux profiles and recombination, particle flux and neutral pressure measurements. Analytic scrape-off layer parallel transport models were used for interpretation of NSTX detachment experiments. The modeling showed that the observed peak heat flux reduction and detachment are possible with high radiated power and momentum loss fractions, achievable with divertor gas injection, and nearly impossible to achieve with main electron density, divertor neutral density or recombination increases alone.
CHANDRA X-RAY AND HUBBLE SPACE TELESCOPE IMAGING OF OPTICALLY SELECTED KILOPARSEC-SCALE BINARY ACTIVE GALACTIC NUCLEI. II. HOST GALAXY MORPHOLOGY AND AGN ACTIVITY

International Nuclear Information System (INIS)

Shangguan, Jinyi; Ho, Luis C.; Liu, Xin; Shen, Yue; Peng, Chien Y.; Greene, Jenny E.; Strauss, Michael A.

2016-01-01

Binary active galactic nuclei (AGNs) provide clues to how gas-rich mergers trigger and fuel AGNs and how supermassive black hole (SMBH) pairs evolve in a gas-rich environment. While significant effort has been invested in their identification, the detailed properties of binary AGNs and their host galaxies are still poorly constrained. In a companion paper, we examined the nature of ionizing sources in the double nuclei of four kiloparsec-scale binary AGNs with redshifts between 0.1 and 0.2. Here, we present their host galaxy morphology based on F336W ( U -band) and F105W ( Y -band) images taken by the Wide Field Camera 3 on board the Hubble Space Telescope . Our targets have double-peaked narrow emission lines and were confirmed to host binary AGNs with follow-up observations. We find that kiloparsec-scale binary AGNs occur in galaxy mergers with diverse morphological types. There are three major mergers with intermediate morphologies and a minor merger with a dominant disk component. We estimate the masses of the SMBHs from their host bulge stellar masses and obtain Eddington ratios for each AGN. Compared with a representative control sample drawn at the same redshift and stellar mass, the AGN luminosities and Eddington ratios of our binary AGNs are similar to those of single AGNs. The U − Y color maps indicate that clumpy star-forming regions could significantly affect the X-ray detection of binary AGNs, e.g., the hardness ratio. Considering the weak X-ray emission in AGNs triggered in merger systems, we suggest that samples of X-ray-selected AGNs may be biased against gas-rich mergers.
Special Lagrangian torus fibrations of complete intersection Calabi–Yau manifolds: A geometric conjecture

Energy Technology Data Exchange (ETDEWEB)

Morrison, David R., E-mail: drm@physics.ucsb.edu [Departments of Mathematics and Physics, U.C. Santa Barbara, Santa Barbara, CA 93106 (United States); Ronen Plesser, M. [Center for Geometry and Theoretical Physics, Duke University, Durham NC 27708 (United States)

2015-09-15

For complete intersection Calabi–Yau manifolds in toric varieties, Gross and Haase–Zharkov have given a conjectural combinatorial description of the special Lagrangian torus fibrations whose existence was predicted by Strominger, Yau and Zaslow. We present a geometric version of this construction, generalizing an earlier conjecture of the first author.
Superdeformed nuclei

International Nuclear Information System (INIS)

Janssens, R.V.F.; Khoo, T.L.

1991-01-01

Superdeformation was first proposed some twenty years ago to explain the fission isomers observed in some actinide nuclei. It was later realized that superdeformed shapes can occur at high angular momentum in lighter nuclei. The interest in the mechanisms responsible for these exotic shapes has increased enormously with the discovery of a superdeformed band of nineteen discrete lines in 152 Dy (8). At about the same time, evidence for highly deformed nuclei (axis ratio 3:2) was also reported near 132 Ce(9). Striking properties emerged from the first experiments, such as the essentially constant energy spacing between transitions (picket-fence spectra), the unexpectedly strong population of superdeformed bands at high spins, and the apparent lack of a link between the superdeformed states and the yrast levels. These findings were reviewed by Nolan and Twin. The present article follows upon their work and discusses the wealth of information that has since become available. This includes the discovery of a new island of superdeformation near A = 190, the detailed spectroscopy of ground and excited bands in the superdeformed well near A = 150 and A = 190, the surprising occurrence of superdeformed bands with identical transition energies in nuclei differing by one or two mass units, and the improved understanding of mechanisms responsible for the feeding into and the decay out of the superdeformed states
Structure of neutron-rich nuclei

International Nuclear Information System (INIS)

Nazarewicz, W.

2000-01-01

Complete text of publication follows. The uncharted regions of the (N,Z) plane contain information that can answer many questions of fundamental importance for science: How many protons and neutrons can be clustered together by the strong interaction to form a bound nucleus? What are the proton and neutron magic numbers of the exotic nuclei? What are the properties of very short-lived exotic nuclei with extreme neutron-to-proton ratios? What is the effective nucleon-nucleon interaction in a nucleus that has a very large neutron excess? Nuclear life far from stability is different from that around the stability line; the promised access to completely new combinations of proton and neutron numbers offers prospects for new structural phenomena. The main objective of this talk is to discuss some of the challenges and opportunities of research with exotic nuclei. The covered topics will include: Theoretical challenges; Skins and halos in heavy nuclei; Shape coexistence in exotic nuclei; Beta-decays of neutron-rich nuclei. (author)
Spectrin-like proteins in plant nuclei

NARCIS (Netherlands)

Ruijter, de N.C.A.; Ketelaar, T.; Blumenthal, S.S.D.; Emons, A.M.C.; Schel, J.H.N.

2000-01-01

We analysed the presence and localization of spectrin-like proteins in nuclei of various plant tissues, using several anti-erythrocyte spectrin antibodies on isolated pea nuclei and nuclei in cells. Western blots of extracted purified pea nuclei show a cross-reactive pair of bands at 220–240 kDa,
Energetic Nuclei, Superdensity and Biomedicine

Science.gov (United States)

Baldin, A. M.

1977-01-01

High-energy, relativistic nuclei were first observed in cosmic rays. Studing these nuclei has provided an opportunity for analyzing the composition of cosmic rays and for experimentally verifying principles governing the behavior of nuclear matter at high and super-high temperatures. Medical research using accelerated nuclei is suggested.…
Problem of ''deformed'' superheavy nuclei

International Nuclear Information System (INIS)

Sobiczewski, A.; Patyk, Z.; Muntian, I.

2000-08-01

Problem of experimental confirmation of deformed shapes of superheavy nuclei situated in the neighbourhood of 270 Hs is discussed. Measurement of the energy E 2+ of the lowest 2+ state in even-even species of these nuclei is considered as a method for this confirmation. The energy is calculated in the cranking approximation for heavy and superheavy nuclei. The branching ratio p 2+ /p 0+ between α decay of a nucleus to this lowest 2+ state and to the ground state 0+ of its daughter is also calculated for these nuclei. The results indicate that a measurement of the energy E 2+ for some superheavy nuclei by electron or α spectroscopy is a promising method for the confirmation of their deformed shapes. (orig.)
Fusion advanced studies Torus

International Nuclear Information System (INIS)

2007-01-01

The successful development of ITER and DEMO scenarios requires preparatory activities on devices that are smaller than ITER, sufficiently flexible and capable of investigating the peculiar physics of burning plasma conditions. The aim of the Fusion Advanced Studies Torus (FAST) proposal [2.1] (formerly FT3 [2.2]) is to show that the preparation of ITER scenarios and the development of new expertise for the DEMO design and RD can be effectively implemented on a new facility. FAST will a) operate with deuterium plasmas, thereby avoiding problems associated with tritium, and allow investigation of nonlinear dynamics (which are important for understanding alpha particle behaviour in burning plasmas) by using fast ions accelerated by heating and current drive systems; b) work in a dimensionless parameter range close to that of ITER; c) test technical innovative solutions, such as full-tungsten plasma-facing components and an advanced liquid metal divertor target for the first wall/divertor, directly relevant for ITER and DEMO; d) exploit advanced regimes with a much longer pulse duration than the current diffusion time; e) provide a test bed for ITER and DEMO diagnostics; f) provide an ideal framework for model and numerical code benchmarks, their verification and validation in ITER/ DEMO-relevant plasma conditions
Critical-point nuclei

International Nuclear Information System (INIS)

Clark, R.M.

2004-01-01

It has been suggested that a change of nuclear shape may be described in terms of a phase transition and that specific nuclei may lie close to the critical point of the transition. Analytical descriptions of such critical-point nuclei have been introduced recently and they are described briefly. The results of extensive searches for possible examples of critical-point behavior are presented. Alternative pictures, such as describing bands in the candidate nuclei using simple ΔK = 0 and ΔK = 2 rotational-coupling models, are discussed, and the limitations of the different approaches highlighted. A possible critical-point description of the transition from a vibrational to rotational pairing phase is suggested
The theory of pseudo-differential operators on the noncommutative n-torus

Science.gov (United States)

Tao, J.

2018-02-01

The methods of spectral geometry are useful for investigating the metric aspects of noncommutative geometry and in these contexts require extensive use of pseudo-differential operators. In a foundational paper, Connes showed that, by direct analogy with the theory of pseudo-differential operators on finite-dimensional real vector spaces, one may derive a similar pseudo-differential calculus on noncommutative n-tori, and with the development of this calculus came many results concerning the local differential geometry of noncommutative tori for n=2,4, as shown in the groundbreaking paper in which the Gauss-Bonnet theorem on the noncommutative two-torus is proved and later papers. Certain details of the proofs in the original derivation of the calculus were omitted, such as the evaluation of oscillatory integrals, so we make it the objective of this paper to fill in all the details. After reproving in more detail the formula for the symbol of the adjoint of a pseudo-differential operator and the formula for the symbol of a product of two pseudo-differential operators, we extend these results to finitely generated projective right modules over the noncommutative n-torus. Then we define the corresponding analog of Sobolev spaces and prove equivalents of the Sobolev and Rellich lemmas.
Cluster structures in light nuclei

International Nuclear Information System (INIS)

Horiuchi, H.

2000-01-01

Complete text of publication follows. Clustering in neutron-rich nuclei is discussed. To understand the novel features (1,2,3) of the clustering in neutron-rich nuclei, the basic features of the clustering in stable nuclei (4) are briefly reviewed. In neutron-rich nuclei, the requirement of the stability of clusters is questioned and the threshold rule is no more obeyed. Examples of clustering in Be and B isotopes (4,5) are discussed in some detail. Possible existence of novel type of clustering near neutron dripline is suggested (1). (author)
Inelastic collisions of neon-22 nuclei with nuclei in photoemulsion at 90 GeV/c momentum

International Nuclear Information System (INIS)

Vokalova, A.; Krasnov, S.A.; Tolstov, K.D.

1985-01-01

The experimental data obtained according to the analysis of 4303 inelastic interactions of the relativistic neon-22 nuclei with the nuclei in photoemulsion are presented. The multiplicities and angular distributions are shown as the functions of the disintegration degree of the colliding nuclei. It is shown that the same number of interacting nucleons of the projectile neon and carbon nuclei are connected with the different impact parameters with the target nucleus
Interactions of 10.6 GeV/n gold nuclei with light and heavy target nuclei in nuclear emulsion

International Nuclear Information System (INIS)

Cherry, M.L.; Denes-Jones, P.

1994-03-01

We have investigated the particle production and fragmentation of nuclei participating in the interactions of 10.6 GeV/n gold nuclei in nuclear emulsions. A new criteria has been developed to distinguish between the interactions of these gold nuclei with the light (H, C, N, O) and heavy (Ag, Br) target nuclei in the emulsion. This has allowed separate analyzes of the multiplicity and pseudo-rapidity distributions of the singly charged particles emitted in Au-(H, C, N, O) and Au-(Ag, Br) interactions, as well as of the models of breakup of the projectile and target nuclei. The pseudo-rapidity distributions show strong forward asymmetries, particularly for the interactions with the light nuclei. Heavy target nuclei produce a more severe breakup of the projectile gold nucleus than do the lighter targets. A negative correlation between the number of fragments emitted from the target nuclei and the degree of centrality of the collisions has been observed, which can be attributed to the total destruction of the relatively light target nuclei by these very heavy projectile nuclei. (author). 14 refs, 11 figs, 1 tab

Characterization and parametric dependencies of low wavenumber pedestal turbulence in the National Spherical Torus Experiment

Energy Technology Data Exchange (ETDEWEB)

Smith, D. R.; Fonck, R. J.; McKee, G. R.; Thompson, D. S. [Department of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Bell, R. E.; Diallo, A.; Guttenfelder, W.; Kaye, S. M.; LeBlanc, B. P.; Podesta, M. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2013-05-15

The spherical torus edge region is among the most challenging regimes for plasma turbulence simulations. Here, we measure the spatial and temporal properties of ion-scale turbulence in the steep gradient region of H-mode pedestals during edge localized mode-free, MHD quiescent periods in the National Spherical Torus Experiment. Poloidal correlation lengths are about 10 ρ{sub i}, and decorrelation times are about 5 a/c{sub s}. Next, we introduce a model aggregation technique to identify parametric dependencies among turbulence quantities and transport-relevant plasma parameters. The parametric dependencies show the most agreement with transport driven by trapped-electron mode, kinetic ballooning mode, and microtearing mode turbulence, and the least agreement with ion temperature gradient turbulence. In addition, the parametric dependencies are consistent with turbulence regulation by flow shear and the empirical relationship between wider pedestals and larger turbulent structures.
Quarks in Few Body Nuclei

Directory of Open Access Journals (Sweden)

Holt Roy J.

2016-01-01

Full Text Available Electron scattering at very high Bjorken x from hadrons provides an excellent test of models, has an important role in high energy physics, and from nuclei, provides a window into short range correlations. Light nuclei have a key role because of the relatively well-known nuclear structure. The development of a novel tritium target for Jefferson Lab has led to renewed interest in the mass three system. For example, deep inelastic scattering experiments in the light nuclei provide a powerful means to determine the neutron structure function. The isospin dependence of electron scattering from mass-3 nuclei provide information on short range correlations in nuclei. The program using the new tritium target will be presented along with a summary of other experiments aimed at revealing the large-x structure of the nucleon.
Confinement of Neutral Beam Ions in the National Spherical Torus Experiment

International Nuclear Information System (INIS)

Darrow, D.S.; Medley, S.S.; Roquemore, A.L.; Rosenberg, A.

2001-01-01

The loss of neutral-beam ions to the wall has been measured in the National Spherical Torus Experiment (NSTX) by means of thermocouples, an infrared (IR) camera, and a Faraday cup probe. The losses tend to exhibit the expected dependences on plasma current, tangency radius of the injector, and plasma outer gap. However, the thermocouples and the Faraday cups indicate substantially different levels of loss and this difference has yet to be understood
Hierarchical Cantor set in the large scale structure with torus geometry

Energy Technology Data Exchange (ETDEWEB)

Murdzek, R. [Physics Department, ' Al. I. Cuza' University, Blvd. Carol I, Nr. 11, Iassy 700506 (Romania)], E-mail: rmurdzek@yahoo.com

2008-12-15

The formation of large scale structures is considered within a model with string on toroidal space-time. Firstly, the space-time geometry is presented. In this geometry, the Universe is represented by a string describing a torus surface. Thereafter, the large scale structure of the Universe is derived from the string oscillations. The results are in agreement with the cellular structure of the large scale distribution and with the theory of a Cantorian space-time.
Complete destruction of heavy nuclei by hadrons and nuclei

International Nuclear Information System (INIS)

Tolstov, K.D.

1980-01-01

The total disintegration is considered of Ag and Pb nuclei and 4 He, 12 C nuclei With a momentum of 4.5 GeV/c per nucleon. It is shown that nucleons are mainly emitted, and there is no residual nUcleus the mass of which is comparable to that of the primary nucleus. The probability of total nucleus disintegration is considered as a function of projectile energy and the mass. The multiplicity, energy and emission angle of particles are considerred as well. It is shown that the density of nuclear matter in the overlap zone of colliding nuclei exceeds the usual one by a factor of approximately 4. A comparison is made with interaction models. A conclusion is drawn of the collective interaction mechanism (perhaps, of the shock wave type) of particle ejection from the target nucleus at the first stage of interaction and of explosive decay of the residual nucleus at the next one
Lagrangian torus fibration of quintic Calabi-Yau hypersurfaces II: Technical results on gradient flow construction

OpenAIRE

Ruan, Wei-Dong

2004-01-01

This paper is the sequel to my recent paper [10]. It will provide technical details of our gradient flow construction and related problems, which are essential for our construction of Lagrangian torus fibrations in [10] and subsequent papers [11, 13, 14].
High-spin excitations of atomic nuclei

International Nuclear Information System (INIS)

Xu Furong; National Laboratory of Heavy Ion Physics, Lanzhou; Chinese Academy of Sciences, Beijing

2004-01-01

The authors used the cranking shell model to investigate the high-spin motions and structures of atomic nuclei. The authors focus the collective rotations of the A∼50, 80 and 110 nuclei. The A∼50 calculations show complicated g spectroscopy, which can have significant vibration effects. The A≅80 N≅Z nuclei show rich shape coexistence with prolate and oblate rotational bands. The A≅110 nuclei near the r-process path can have well-deformed oblate shapes that become yrast and more stable with increasing rotational frequency. As another important investigation, the authors used the configuration-constrained adiabatic method to calculate the multi-quasiparticle high-K states in the A∼130, 180 and superheavy regions. The calculations show significant shape polarizations due to quasi-particle excitations for soft nuclei, which should be considered in the investigations of high-K states. The authors predicted some important high-K isomers, e.g., the 8 - isomers in the unstable nuclei of 140 Dy and 188 Pb, which have been confirmed in experiments. In superheavy nuclei, our calculations show systematic existence of high-K states. The high-K excitations can increase the productions of synthesis and the survival probabilities of superheavy nuclei. (authors)
The shape of nuclei

International Nuclear Information System (INIS)

Mackintosh, R.S.

1977-01-01

For the class of nuclei which are 'strongly deformed' it is possible to introduce the idea of an empirically measurable static nuclear shape. The limitations of this concept as applied to nuclei (fundamentally quantum-mechanical objects) are discussed. These are basically the limitations of the rotational model which must be introduced in order to define and measure nuclear shape. A unified discussion of the ways in which the shape has been parametrized is given with emphasis on the fact that different parametrizations correspond to different nuclear structures. Accounts of the various theoretical procedures for calculating nuclear shapes and of the interaction between nuclear shapes and nuclear spectroscopy are given. A coherent account of a large subset of nuclei (strongly deformed nuclei) can be given by means of a model in which the concept of nuclear shape plays a central role. (author)
Structure of Warm Nuclei

International Nuclear Information System (INIS)

Aaberg, S.; Uhrenholt, H.

2009-01-01

We study the structure of nuclei in the energy region between the ground state and the neutron separation energy, here called warm nuclei. The onset of chaos in the nucleus as excitation energy is increased is briefly reviewed. Chaos implies fluctuations of energies and wave functions qualitatively the same for all chaotic nuclei. On the other hand, large structure effects are seen, e.g. in the level-density function at same excitation energies. A microscopic model for the level density is reviewed and we discuss effects on structure of the total level-density function, parity enhancement, and the spin distribution function. Comparisons to data are performed at the neutron separation energy for all observed nuclei, and structure of the level-density function for a few measured cases. The role of structure effects in the level-density function for fission dynamics is exemplified.
Dynamic polarisation of nuclei

International Nuclear Information System (INIS)

Borghini, M.; Abragam, A.

1961-01-01

In magnetic fields of about 13000 gauss, at a temperature of 1.5 deg. K, in samples of about 2 mm 3 , we have obtained by the 'solid effect' (application of a magnetic field at an appropriate frequency around 35000 MHz), nuclear polarizations /I of a few percent: 19 per cent for hydrogen nuclei in single crystals of La 2 Mg 3 (NO 3 ) 12 , 24H 2 O; 5 per cent for hydrogen nuclei in polystyrene; 6 per cent for fluorine nuclei in single crystals of LiF. (author) [fr
The Geometry of the Semiclassical Wave Front Set for Schrödinger Eigenfunctions on the Torus

Energy Technology Data Exchange (ETDEWEB)

Cardin, Franco, E-mail: cardin@math.unipd.it; Zanelli, Lorenzo, E-mail: lzanelli@math.unipd.it [University of Padova, Department of Mathematics “Tullio Levi Civita” (Italy)

2017-06-15

This paper deals with the phase space analysis for a family of Schrödinger eigenfunctions ψ{sub ℏ} on the flat torus #Mathematical Double-Struck Capital T#{sup n} = (ℝ/2πℤ){sup n} by the semiclassical Wave Front Set. We study those ψ{sub ℏ} such that WF{sub ℏ}(ψ{sub ℏ}) is contained in the graph of the gradient of some viscosity solutions of the Hamilton-Jacobi equation. It turns out that the semiclassical Wave Front Set of such Schrödinger eigenfunctions is stable under viscous perturbations of Mean Field Game kind. These results provide a further viewpoint, and in a wider setting, of the link between the smooth invariant tori of Liouville integrable Hamiltonian systems and the semiclassical localization of Schrödinger eigenfunctions on the torus.
Control System Development Plan for the National Spherical Torus Experiment

International Nuclear Information System (INIS)

Neumeyer, C.; Mueller, D.; Gates, D.A.; Ferron, J.R.

1999-01-01

The National Spherical Torus Experiment (NSTX) has as one of its primary goals the demonstration of the attractiveness of the spherical torus concept as a fusion power plant. Central to this goal is the achievement of high plasma β ( = 2 micro 0 /B 2 a measure of the efficiency of a magnetic plasma confinement system). It has been demonstrated both theoretically and experimentally that the maximum achievable β is a strong function of both local and global plasma parameters. It is therefore important to optimize control of the plasma. To this end a phased development plan for digital plasma control on NSTX is presented. The relative level of sophistication of the control system software and hardware will be increased according to the demands of the experimental program in a three phase plan. During Day 0 (first plasma), a simple coil current control algorithm will initiate plasma operations. During the second phase (Day 1) of plasma operations the control system will continue to use the preprogrammed algorithm to initiate plasma breakdown but will then change over to a rudimentary plasma control scheme based on linear combinations of measured plasma fields and fluxes. The third phase of NSTX plasma control system development will utilize the rtEFIT code, first used on DIII-D, to determine, in real-time, the full plasma equilibrium by inverting the Grad-Shafranov equation. The details of the development plan, including a description of the proposed hardware will be presented
Diffraction scattering and disintegration of 3He nuclei by atomic nuclei

International Nuclear Information System (INIS)

Koval'chuk, V.I.

2006-01-01

Within diffraction model framework a method of cross sections calculation for scattering and disintegration of weakly-bounded two-clustered nuclei by nuclei when both of its clusters are changed has been proposed. The experimental elastic scattering cross sections of 3 He by 40 Ca, 90 Zr and coincidence spectra of disintegration products from 28 Si( 3 He,dp) have been described
Neutron rich nuclei

International Nuclear Information System (INIS)

Foucher, R.

1979-01-01

If some β - emitters are particularly interesting to study in light, medium, and heavy nuclei, another (and also) difficult problem is to know systematically the properties of these neutron rich nuclei far from the stability line. A review of some of their characteristics is presented. How far is it possible to be objective in the interpretation of data is questioned and implications are discussed
Proposal of a torus pumping and fuel recycling system for ITER

International Nuclear Information System (INIS)

Perinic, D.; Mack, A.; Perinic, G.; Murdoch, D.

1995-01-01

A universal torus pumping and fuel recycling system is proposed for all operation modes of ITER. It comprises primary cryopumps and secondary fuel separating cryopumps located inside the cryostat and a common mechanical forepump station located outside the cryostat. In this paper two different primary cryopump options are compared. The results of Monte Carlo calculations of pumping probabilities for helium show a significant difference leading to a distinct preference for the concept of a co-pumping cryopump. (orig.)
Baryon resonances in nuclei

International Nuclear Information System (INIS)

Arenhoevel, H.

1977-01-01

The field of baryon resonances in nuclei is reviewed. Theoretical developments and experimental evidence as well are discussed. Special emphasis is laid on electromagnetic processes for the two nucleon system. Some aspects of real isobars in nuclei are touched upon. (orig.) [de
Isolation of Nuclei and Nucleoli.

Science.gov (United States)

Pendle, Alison F; Shaw, Peter J

2017-01-01

Here we describe methods for producing nuclei from Arabidopsis suspension cultures or root tips of Arabidopsis, wheat, or pea. These methods could be adapted for other species and cell types. The resulting nuclei can be further purified for use in biochemical or proteomic studies, or can be used for microscopy. We also describe how the nuclei can be used to obtain a preparation of nucleoli.
Controlled thermonuclear fusion in TOKAMAK type reactors, the European example: Joint European Torus (JET)

International Nuclear Information System (INIS)

Paris, P.J.; Yassen, F.; Assis, A.S. de; Raposo, C.

1988-07-01

The development of controlled thermonuclear reaction in TOKAMAK type reactors, and the main projects in the world are presented. The main characteristics of the JET (Joint European Torus) program, the perspectives for energy production, and the international cooperation for viable use of the TOKAMAK are analysed. (M.C.K.) [pt
Nucleons in nuclei, however

International Nuclear Information System (INIS)

Grange, P.; Mathiot, J.F.; Roy-Stephan, M.; Frascaria, R.; Gales, S.

1990-01-01

The topics presented at the 1989 Joliot-Curie Lectures are reported. Two main subjects were retained: a simplified description of the N-body motion of particles in the quasi-particle configuration; study of the dynamics of nuclear components which are not described by nucleons in their ground state. The following themes were presented: quasiparticles and the Green functions, relativistic aspects of the quasiparticle concept, the dimensions of nucleons in the nuclei and the EMC effect, quarks and gluons in the nuclei, the delta in the nuclei, the strangeness, quasiparticles far from the Fermi sea, diffusion of electrons, stellar evolution and nucleosynthesis [fr
Reflection asymmetric shapes in nuclei

International Nuclear Information System (INIS)

Ahmad, I.; Carpenter, M.P.; Emling, H.

1989-01-01

Experimental data show that there is no even-even nucleus with a reflection asymmetric shape in its ground state. Maximum octupole- octupole correlations occur in nuclei in the mass 224 (N∼134, Z∼88) region. Parity doublets, which are the characteristic signature of octupole deformation, have been observed in several odd mass Ra, Ac and Pa nuclei. Intertwined negative and positive parity levels have been observed in several even-even Ra and Th nuclei above spin ∼8ℎ. In both cases, the opposite parity states are connected by fast El transitions. In some medium-mass nuclei intertwined negative and positive parity levels have also been observed above spin ∼7ℎ. The nuclei which exhibit octupole deformation in this mass region are 144 Ba, 146 Ba and 146 Ce; 142 Ba, 148 Ce, 150 Ce and 142 Xe do not show these characteristics. No case of parity doublet has been observed in the mass 144 region. 32 refs., 16 figs., 1 tab

Turbomolecular pump vacuum system for the Princeton Large Torus

International Nuclear Information System (INIS)

Dylla, H.F.

1977-10-01

A turbomolecular pump vacuum system has been designed and installed on the Princeton Large Torus (PLT). Four vertical shaft, oil-bearing, 1500 l/s turbomolecular pumps have been interfaced to the 6400 liter PLT Vacuum vessel to provide a net pumping speed of 3000 l/s for H 2 . The particular requirements and problems of tokamak vacuum systems are enumerated. A vacuum control system is described which protects the vacuum vessel from contamination, and protects the turbomolecular pumps from damage under a variety of possible failure modes. The performance of the vacuum system is presented in terms of pumping speed measurements and residual gas behavior
Monte Carlo neutral density calculations for ELMO Bumpy Torus

International Nuclear Information System (INIS)

Davis, W.A.; Colchin, R.J.

1986-11-01

The steady-state nature of the ELMO Bumpy Torus (EBT) plasma implies that the neutral density at any point inside the plasma volume will determine the local particle confinement time. This paper describes a Monte Carlo calculation of three-dimensional atomic and molecular neutral density profiles in EBT. The calculation has been done using various models for neutral source points, for launching schemes, for plasma profiles, and for plasma densities and temperatures. Calculated results are compared with experimental observations - principally spectroscopic measurements - both for guidance in normalization and for overall consistency checks. Implications of the predicted neutral profiles for the fast-ion-decay measurement of neutral densities are also addressed
Quasi-single helicity spectra in the Madison Symmetric Torus

International Nuclear Information System (INIS)

Marrelli, L.; Martin, P.; Spizzo, G.; Franz, P.; Chapman, B.E.; Craig, D.; Sarff, J.S.; Biewer, T.M.; Prager, S.C.; Reardon, J.C.

2002-01-01

Evidence of a self-organized collapse towards a narrow spectrum of magnetic instabilities in the Madison Symmetric Torus [R. N. Dexter, D. W. Kerst, T. W. Lovell, S. C. Prager, and J. C. Sprott, Fusion Technol. 19, 131 (1991)] reversed field pinch device is presented. In this collapsed state, dubbed quasi-single helicity (QSH), the spectrum of magnetic modes condenses spontaneously to one dominant mode more completely than ever before observed. The amplitudes of all but the largest of the m=1 modes decrease in QSH states. New results about thermal features of QSH spectra and the identification of global control parameters for their onset are also discussed
Precision measurement of the mass difference between light nuclei and anti-nuclei

CERN Document Server

Adam, Jaroslav; Aggarwal, Madan Mohan; Aglieri Rinella, Gianluca; Agnello, Michelangelo; Agrawal, Neelima; Ahammed, Zubayer; Ahmed, Ijaz; Ahn, Sang Un; Aimo, Ilaria; Aiola, Salvatore; Ajaz, Muhammad; Akindinov, Alexander; Alam, Sk Noor; Aleksandrov, Dmitry; Alessandro, Bruno; Alexandre, Didier; Alfaro Molina, Jose Ruben; Alici, Andrea; Alkin, Anton; Alme, Johan; Alt, Torsten; Altinpinar, Sedat; Altsybeev, Igor; Alves Garcia Prado, Caio; Andrei, Cristian; Andronic, Anton; Anguelov, Venelin; Anielski, Jonas; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshaeuser, Harald; Arcelli, Silvia; Armesto Perez, Nestor; Arnaldi, Roberta; Aronsson, Tomas; Arsene, Ionut Cristian; Arslandok, Mesut; Augustinus, Andre; Averbeck, Ralf Peter; Azmi, Mohd Danish; Bach, Matthias Jakob; Badala, Angela; Baek, Yong Wook; Bagnasco, Stefano; Bailhache, Raphaelle Marie; Bala, Renu; Baldisseri, Alberto; Ball, Markus; Baltasar Dos Santos Pedrosa, Fernando; Baral, Rama Chandra; 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Spyropoulou-Stassinaki, Martha; Srivastava, Brijesh Kumar; Stachel, Johanna; Stan, Ionel; Stefanek, Grzegorz; Steinpreis, Matthew Donald; Stenlund, Evert Anders; Steyn, Gideon Francois; Stiller, Johannes Hendrik; Stocco, Diego; Strmen, Peter; Alarcon Do Passo Suaide, Alexandre; Sugitate, Toru; Suire, Christophe Pierre; Suleymanov, Mais Kazim Oglu; Sultanov, Rishat; Sumbera, Michal; Symons, Timothy; Szabo, Alexander; Szanto De Toledo, Alejandro; Szarka, Imrich; Szczepankiewicz, Adam; Szymanski, Maciej Pawel; Takahashi, Jun; Tanaka, Naoto; Tangaro, Marco-Antonio; Tapia Takaki, Daniel Jesus; Tarantola Peloni, Attilio; Tariq, Mohammad; Tarzila, Madalina-Gabriela; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terasaki, Kohei; Terrevoli, Cristina; Teyssier, Boris; Thaeder, Jochen Mathias; Thomas, Deepa; Tieulent, Raphael Noel; Timmins, Anthony Robert; Toia, Alberica; Trogolo, Stefano; Trubnikov, Victor; Trzaska, Wladyslaw Henryk; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ullaland, Kjetil; Uras, Antonio; Usai, Gianluca; Utrobicic, Antonija; Vajzer, Michal; Vala, Martin; Valencia Palomo, Lizardo; Vallero, Sara; Van Der Maarel, Jasper; Van Hoorne, Jacobus Willem; Van Leeuwen, Marco; Vanat, Tomas; Vande Vyvre, Pierre; Varga, Dezso; Diozcora Vargas Trevino, Aurora; Vargyas, Marton; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vauthier, Astrid; Vechernin, Vladimir; Veen, Annelies Marianne; Veldhoen, Misha; Velure, Arild; Venaruzzo, Massimo; Vercellin, Ermanno; Vergara Limon, Sergio; Vernet, Renaud; Verweij, Marta; Vickovic, Linda; Viesti, Giuseppe; Viinikainen, Jussi Samuli; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Vinogradov, Alexander; Vinogradov, Leonid; Vinogradov, Yury; Virgili, Tiziano; Vislavicius, Vytautas; Viyogi, Yogendra; Vodopyanov, Alexander; Volkl, Martin Andreas; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; Von Haller, Barthelemy; Vorobyev, Ivan; Vranic, Danilo; Vrlakova, Janka; Vulpescu, Bogdan; Vyushin, Alexey; Wagner, Boris; Wagner, Jan; Wang, Hongkai; Wang, Mengliang; Wang, Yifei; Watanabe, Daisuke; Weber, Michael; Weber, Steffen Georg; Wessels, Johannes Peter; Westerhoff, Uwe; Wiechula, Jens; Wikne, Jon; Wilde, Martin Rudolf; Wilk, Grzegorz Andrzej; Wilkinson, Jeremy John; Williams, Crispin; Windelband, Bernd Stefan; Winn, Michael Andreas; Yaldo, Chris G; Yamaguchi, Yorito; Yang, Hongyan; Yang, Ping; Yano, Satoshi; Yasnopolskiy, Stanislav; Yin, Zhongbao; Yokoyama, Hiroki; Yoo, In-Kwon; Yurchenko, Volodymyr; Yushmanov, Igor; Zaborowska, Anna; Zaccolo, Valentina; Zaman, Ali; Zampolli, Chiara; Correia Zanoli, Henrique Jose; Zaporozhets, Sergey; Zarochentsev, Andrey; Zavada, Petr; Zavyalov, Nikolay; Zbroszczyk, Hanna Paulina; Zgura, Sorin Ion; Zhalov, Mikhail; Zhang, Haitao; Zhang, Xiaoming; Zhang, Yonghong; Zhao, Chengxin; Zhigareva, Natalia; Zhou, Daicui; Zhou, You; Zhou, Zhuo; Zhu, Hongsheng; Zhu, Jianhui; Zhu, Xiangrong; Zichichi, Antonino; Zimmermann, Alice; Zimmermann, Markus Bernhard; Zinovjev, Gennady; Zyzak, Maksym

2015-08-17

The measurement of the mass differences for systems bound by the strong force has reached a very high precision with protons and anti-protons. The extension of such measurement from (anti-)baryons to (anti-)nuclei allows one to probe any difference in the interactions between nucleons and anti-nucleons encoded in the (anti-)nuclei masses. This force is a remnant of the underlying strong interaction among quarks and gluons and can be described by effective theories, but cannot yet be directly derived from quantum chromodynamics. Here we report a measurement of the difference between the ratios of the mass and charge of deuterons (d) and anti-deuterons ($\\bar{d}$), and $^{3}{\\rm He}$ and $^3\\overline{\\rm He}$ nuclei carried out with the ALICE (A Large Ion Collider Experiment) detector in Pb-Pb collisions at a centre-of-mass energy per nucleon pair of 2.76 TeV. Our direct measurement of the mass-over-charge differences confirm CPT invariance to an unprecedented precision in the sector of light nuclei. This funda...
Electron energy confinement in ELMO Bumpy Torus (EBT)

International Nuclear Information System (INIS)

Hiroe, S.; Haste, G.R.; Dandl, R.A.

1979-06-01

Using a calibrated, solid-state, soft x-ray detector, the electron temperature and density have been measured over a wide range of operating conditions of ELMO Bumpy Torus (EBT). The empirical relations of the temperature or the density to the microwave power and the ambient pressure have been determined. The toroidally stored energy has been observed to increase as the stored energy of the hot electron annulus increases. The energy confinement time has been obtained for various plasma parameters and has been found to agree with the neoclassical theory. The advantages of EBT collisionless scaling for fusion plasma confinement have been noted, i.e., n/sub e/tau/sub E/ increases as T/sub e/ 1 5 in the collisionless regime
Polynomial invariants for torus knots and topological strings

International Nuclear Information System (INIS)

Labastida, J.M.F.

2001-01-01

We make a precision test of a recently proposed conjecture relating Chern-Simons gauge theory to topological string theory on the resolution of the conifold. First, we develop a systematic procedure to extract string amplitudes from vacuum expectation values (vevs) of Wilson loops in Chern-Simons gauge theory, and then we evaluate these vevs in arbitrary irreducible representations of SU(N) for torus knots. We find complete agreement with the predictions derived from the target space interpretation of the string amplitudes. We also show that the structure of the free energy of topological open string theory gives further constraints on the Chern-Simons vevs. Our work provides strong evidence towards an interpretation of knot polynomial invariants as generating functions associated to enumerative problems. (orig.)
Barriers in the energy of deformed nuclei

Directory of Open Access Journals (Sweden)

V. Yu. Denisov

2014-06-01

Full Text Available Interaction energy between two nuclei considering to their deformations is studied. Coulomb and nuclear in-teraction energies, as well as the deformation energies of both nuclei, are taken into account at evaluation of the interaction energy. It is shown that the barrier related to the interaction energy of two nuclei depends on the de-formations and the height of the minimal barrier is evaluated. It is obtained that the heavier nucleus-nucleus sys-tems have large deformation values at the lowest barrier. The difference between the barrier between spherical nuclei and the lowest barrier between deformed nuclei increases with the mass and the charge of the interacting nuclei.
Finite element circuit theory of the numerical code EDDYMULT for solving eddy current problems in a multi-torus system

International Nuclear Information System (INIS)

Nakamura, Yukiharu; Ozeki, Takahisa

1986-07-01

The finite element circuit theory is extended to the general eddy current problem in a multi-torus system, which consists of various torus conductors and axisymmetric coil systems. The numerical procedures are devised to avoid practical restrictions of computer storage and computing time, that is, the reduction technique of eddy current eigen modes to save storage and the introduction of shape function into the double area integral of mode coupling to save time. The numerical code EDDYMULT based on the theory is developed to use in designing tokamak device from the viewpoints of the evaluation of electromagnetic loading on the device components and the control analysis of tokamak equilibrium. (author)
Thickness mapping of submerged portions of a BWR torus using an ROV

International Nuclear Information System (INIS)

Somers, T.; Bagley, J.G.

1992-01-01

A methodology has been developed for establishing an ultrasonic baseline of the submerged portions of a boiling water reactor torus shell. A remotely operated vehicle (ROV) is equipped to deliver an array of ultrasonic thickness transducers to within a fixed stand-off from the shell. The position of the transducers at each ultrasound reading is measured and recorded using a precision acoustic navigation system. The resulting thickness contour map makes it possible to visualize the condition of the torus shell and provides quantitative documentation of shell thickness at a large number of known locations. The navigation system can be reinstalled in the future so that by comparing future thickness readings acquired at the same location, it is possible to create a map of the rate of change in shell thickness. An ultrasonic thickness survey was conducted recently using a preliminary version of such a system. The experience gained in performing this survey has been incorporated in the design of a full-scale prototype system, which is currently under development. This system will include such features as automatic control of the ROV based on the acoustic navigation data, generation of three-dimensional thickness maps, and remote control of the data acquisition process from outside the radiation area
Calculations of Neutral Beam Ion Confinement for the National Spherical Torus Experiment

International Nuclear Information System (INIS)

Redi, M.H.; Darrow, D.S.; Egedal, J.; Kaye, S.M.; White, R.B.

2002-01-01

The spherical torus (ST) concept underlies several contemporary plasma physics experiments, in which relatively low magnetic fields, high plasma edge q, and low aspect ratio combine for potentially compact, high beta and high performance fusion reactors. An important issue for the ST is the calculation of energetic ion confinement, as large Larmor radius makes conventional guiding center codes of limited usefulness and efficient plasma heating by RF and neutral beam ion technology requires minimal fast ion losses. The National Spherical Torus Experiment (NSTX) is a medium-sized, low aspect ratio ST, with R=0.85 m, a=0.67 m, R/a=1.26, Ip*1.4 MA, Bt*0.6 T, 5 MW of neutral beam heating and 6 MW of RF heating. 80 keV neutral beam ions at tangency radii of 0.5, 0.6 and 0.7 m are routinely used to achieve plasma betas above 30%. Transport analyses for experiments on NSTX often exhibit a puzzling ion power balance. It will be necessary to have reliable beam ion calculations to distinguish among the source and loss channels, and to explore the possibilities for new physics phenomena, such as the recently proposed compressional Alfven eigenmode ion heating
Structure of Light Neutron-rich Nuclei

International Nuclear Information System (INIS)

Dlouhy, Zdenek

2007-01-01

In this contribution we searched for irregularities in various separation energies in the frame of mass measurement of neutron-rich nuclei at GANIL. On this basis we can summarize that the new doubly magic nuclei are 8 He, 22 O and 24 O. They are characterized by extra stability and, except 24 O, they cannot accept and bind additional neutrons. However, if we add to these nuclei a proton we obtain 9 Li and 25 F which are the core for two-neutron halo nucleus 11 Li and enables that fluorine can bound even 6 more neutrons, respectively. In that aspect the doubly magic nuclei in the neutron-rich region can form the basis either for neutron halo or very neutron-rich nuclei. (Author)
Cosmology and unstable nuclei

International Nuclear Information System (INIS)

Schramm, D.N.

1995-01-01

Primordial nucleosynthesis has established itself as one of the three pillars of Big Bang cosmology. Many of the Big Bang Nucleosynthesis reactions involve unstable nuclei. Hence there is a tight relationship hetween the subject of this conference and cosmology. The prime role of unstable nuclei in cosmology is related to lithium synthesis and the lack of cosmological synthesis of Be and B. These nuclei will thus be focused upon. Nucleosynthesis involves comparing calculated abundances with observed abundances. In general, abundance determinations are dominated by systematic rather than statistical errors, and work on bounding systematics is crucial. The quark-hadron inspired inhomogeneous calculations now unanimously agree that only relatively small variations in Ω b are possible vis-a-vis the homogeneous model; hence the robustness of Ω b ∼0.05 is now apparent. (These calculations depend critically on unstable nuclei.) The above argues that the bulk of the baryons in the universe are not producing visible light. A comparison with the ROSAT cluster data is also shown to be consistent with the standard BBN model. Ω b ∼1 seems to be definitely excluded, so if Ω TOTAL =1, as some recent observations may hint, then non-baryonic dark matter is required. The implications of the recently reported halo microlensing events are discussed. In summary, it is argued that the physics of unstable nuclei affects the fundamental dark matter argument. ((orig.))
Vibrational-rotational model of odd-odd nuclei

International Nuclear Information System (INIS)

Afanas'ev, A.V.; Guseva, T.V.; Tamberg, Yu.Ya.

1988-01-01

The rotational vibrational (RV) model of odd nuclei is generalized to odd-odd nuclei. The hamiltonian, wave functions and matrix elements of the RV-model of odd-odd nuclei are obtained. The expressions obtained for matrix elements of the RV-model of odd-odd nuclei can be used to study the role of vibrational additions in low-lying two-particle states of odd-odd deformed nuclei. Such calculations permit to study more correctly the residual neutron-proton interaction of valent nucleons with respect to collectivization effects
Nuclei with exotic constituents

International Nuclear Information System (INIS)

Yamazaki, Toshimitsu.

1990-08-01

We discuss various interesting features in the behavior of exotic constituents of nuclei such as hyperons and mesons, in particular, with emphases on the aspect of exotic halos which are formed in general by short-range repulsion and long-range attraction. Specifically, Λ and Σ hypernuclei and pionic nuclei are discussed. (author)
The colours of Hubble Sc galaxy nuclei

International Nuclear Information System (INIS)

Iskudaryan, S.G.

1975-01-01

The colorimetric data on the nuclei of the Sc galaxies are given. Comparison of the following parameters: color of a nucleus, integral color of a galaxy, Byurakan class, and spectral type of normal spirals gives the possibility to conclude: (1) The colors of the nuclei of the Sc galaxies have a high dispersion in its values. In all Byurakan classes the galaxies with intensely red and blue nuclei occur; (2) Some Sc galaxies exhibit a discrepancy between the spectral and morphological types. The results of colorimetry of nuclei indicate that almost all such Sc galaxies have intensely red nuclei which, naturally, provide for these late spectral types. It can be assumed that the intensely red color of the nuclei of such Sc galaxies is a result of a new type of activity of these nuclei; and (3) some Sc galaxies show the characteristics of the Markarian objects
A Direct Approach to the Villarceau Circles of a Torus.

Science.gov (United States)

1984-03-01

8217 following theorem . , Theorem 1. On F and F’ we select points P and P’, respectively, such that (4) 8 "LAOP, * =LAO’P’, (0 ( 8, * < 2), bi X,$ x ~-2- i4...6) by replacing c by -c. Proof of Theorem 1. In the cartesian, axes O’xyz of Fig. I we have .1, 1)P: x c + aoo 0, y- a sin0, z 0 -3- We now rotate...Bottema, Cirkels op een torus, Pythagoras , 19 (1979) 2 7. 2. Z. A. Nelzak, Invitation to Geometry, John Wiley & Sons, New York, 1983. 3. Y. Villarceau
On the geometry of certain irreducible non-torus plane sextics

DEFF Research Database (Denmark)

Eyral, Christophe; Oka, Mutsuo

2009-01-01

An irreducible non-torus plane sextic with simple singularities is said to be special if its fundamental group factors to a dihedral group. There exist (exactly) ten configurations of simple singularities that are realizable by such curves. Among them, six are realizable by non-special sextics...... as well. We conjecture that for each of these six configurations there always exists a non-special curve whose fundamental group is abelian, and we prove this conjecture for three configurations (another one has already been treated in one of our previous papers). As a corollary, we obtain new explicit...
Nuclei in high forms

International Nuclear Information System (INIS)

Szymanski, Z.; Berger, J.F.; Heenen, P.H.; Heyde, K.; Haas, B.; Janssens, R.; Paya, D.; Gogny, D.; Huber, G.; Bjoernholm, S.; Brack, M.

1991-01-01

The purpose of 1991 Joliot-Curie Summer School is to review the most advances in the understanding of the nuclei physics after the considerable progress in gamma spectroscopy. It covers the following topics: Highly and super-deformed nuclei, nuclear structures, mean-field approach and beyond, fission isomers, nuclear excitations with long lifetime and metal clusters
Exotic nuclei: another aspect of nuclear structure

International Nuclear Information System (INIS)

Dobaczewski, J.; Blumenfeld, Y.; Flocard, H.; Garcia Borge, M.J.; Nowacki, F.; Rombouts, S.; Theisen, Ch.; Marques, F.M.; Lacroix, D.; Dessagne, P.; Gaeggeler, H.

2002-01-01

This document gathers the lectures made at the Joliot Curie international summer school in 2002 whose theme that year was exotic nuclei. There were 11 contributions whose titles are: 1) interactions, symmetry breaking and effective fields from quarks to nuclei; 2) status and perspectives for the study of exotic nuclei: experimental aspects; 3) the pairing interaction and the N = Z nuclei; 4) borders of stability region and exotic decays; 5) shell structure of nuclei: from stability to decay; 6) variational approach of system with a few nucleons; 7) from heavy to super-heavy nuclei; 8) halos, molecules and multi-neutrons; 9) macroscopic approaches for fusion reactions; 10) beta decay: a tool for spectroscopy; 11) the gas phase chemistry of super-heavy elements
Exotic nuclei and radioactive beams

International Nuclear Information System (INIS)

Chomaz, P.

1996-01-01

The Nuclei called exotic are all the nuclei that it is necessary to recreate in laboratory to study them. Their life time is too short -in relation to earth age- for it remains enough on earth. The researchers are going to have at their s disposal at GANIL (Caen) with the S.P.I.R.A.L. project, exotic nuclei beams and will study new kinds of nuclear reactions to better understand the atom nucleus. (N.C.). 2 refs., 9 figs

Isotope shifts in unstable nuclei

International Nuclear Information System (INIS)

Rebel, H.

1980-05-01

Current experimental investigations of isotope shifts in atomic spectra of unstable nuclei and the resulting information about size and shape of nuclei far off stability are discussed with reference to some representative examples. (orig.)
Dynamic polarization of radioactive nuclei

International Nuclear Information System (INIS)

Kiselev, Yu.F.; Lyuboshits, V.L.; )

2001-01-01

Radioactive nuclei, embedded into a frozen polarized proton target, atr proposed to polarize by means of some dynamic polarization methods. Angular distributions of γ-quanta emitted ny 22 Na(3 + ) in the cascade β-γ-radiation are calculated. It is shown that this distribution does not depend on the spin temperature sing at the Boltzmann distribution of populations among the Zeeman magnetic substates, whereas the tensor polarization of quadrupole nuclei, placed in the electric field of the crystal, causes the considerable sing dependence. The new method promises wide opportunities for the magnetic structure investigations as well as for the study of spin-spin interaction dynamics of rare nuclei in dielectrics. Physical-technical advantages and disadvantages of the given method are discussed for the polarization of heavy nuclei in the on-line implantation mode [ru
Latitudinal oscillations of plasma within the Io torus

Science.gov (United States)

Cummings, W. D.; Dessler, A. J.; Hill, T. W.

1980-01-01

The equilibrium latitude and the period of oscillations about this equilibrium latitude are calculated for a plasma in a centrifugally dominated tilted dipole magnetic field representing Jupiter's inner magnetosphere. It is found that for a hot plasma the equilibrium latitude in the magnetic equator, for a cold plasma it is the centrifugal equator, and for a warm plasma it is somewhere in between. An illustrative model is adopted in which atoms are sputtered from the Jupiter-facing hemisphere of Io and escape Io's gravity to be subsequently ionized some distance from Io. Finally, it is shown that ionization generally does not occur at the equilibrium altitude, and that the resulting latitudinal oscillations provide an explanation for the irregularities in electron concentration within the torus, as reported by the radioastronomy experiment aboard Voyager I.
Eta mesons in nuclei

International Nuclear Information System (INIS)

Liu, L.C.

1987-01-01

The possibility of producing eta-mesic nuclei by the use of pions is discussed. If these nuclei are observed experimentally, then the binding energies of the eta in this new nuclear matter can be used to extract accurately the eta-N-N* coupling constant in a nucleus. The framework for these calculations is the coupled channel isobar model
The European Communities (Privileges of the Joint European Torus) Order 1978 (S.I. no. 1033)

International Nuclear Information System (INIS)

1978-01-01

This Order confers privileges on the Joint European Torus, as required by Decision 78/472/Euratom of 30 May 1978 of the Council of the European Communities and by the Exchange of Letters of 3 May 1978 between the Government of the United Kingdom and the European Atomic Energy Community [fr
Multifragmentation of hot nuclei

International Nuclear Information System (INIS)

Tamain, B.

1990-10-01

It is difficult to deposit a large amount (∼ 1 Gev) of excitation energy into a nucleus. And if one wants to deposit large excitation energy values, the best way consists of shooting a given target nucleus with several nucleons, which can be achieved by using intermediate energy (10-100 MeV/nucleon) heavy ions. Such very excited objects were named hot nuclei. The study of hot nuclei has been undertaken only for 7 years because intermediate energy heavy ion facilities were not available before. The game is then to determine the decay properties of such nuclei, their limits of existence. Their study is connected with general properties of nuclear matter: namely its equation of state. Of special interest, is the onset of a new decay mechanism: multifragmentation, which is the non-sequential disassembly of a hot nucleus into several light nuclei (often called intermediate-mass fragments or IMF) or particles. This paper, shows how this mechanism can reflect fundamental properties of nuclear matter, but also how its experimental signature is difficult to establish. Multifragmentation has also been studied by using very energetic projectiles (protons and heavy ions) in the relativistic or ultra-relativistic region. The multifragmentation question of hot nuclei is far from being solved. One knows that IMF production increases when the excitation energy brought into a system is strongly increased, but very little is known about the mechanisms involved and a clear onset for multifragmentation is not established
Initial Results from the Lost Alpha Diagnostics on Joint European Torus

Energy Technology Data Exchange (ETDEWEB)

Darrow, Doug; Cecil, Ed; Ellis, Bob; Fullard, Keith; Hill, Ken; Horton, Alan; Kiptily, Vasily; Pedrick, Les; Reich, Matthias

2007-07-25

Two devices have been installed in the Joint European Torus (JET) vacuum vessel near the plasma boundary to investigate the loss of energetic ions and fusion products in general and alpha particles in particular during the upcoming JET experiments. These devices are (i) a set of multichannel thin foil Faraday collectors, and (ii) a well collimated scintillator which is optically connected to a charge-coupled device. Initial results, including the radial energy and poloidal dependence of lost ions from hydrogen and deuterium plasmas during the 2005–06 JET restart campaign, will be presented.
Initial Results from the Lost Alpha Diagnostics on Joint European Torus

International Nuclear Information System (INIS)

Darrow, Doug; Baeumel, Stefan; Cecil, Ed; Ellis, Bob; Fullard, Keith; Hill, Ken; Horton, Alan; Kiptily, Vasily; Pedrick, Les; Reich, Matthias; Werner, Andreas

2007-01-01

Two devices have been installed in the Joint European Torus (JET) vacuum vessel near the plasma boundary to investigate the loss of energetic ions and fusion products in general and alpha particles in particular during the upcoming JET experiments. These devices are (i) a set of multichannel thin foil Faraday collectors, and (ii) a well collimated scintillator which is optically connected to a charge-coupled device. Initial results, including the radial energy and poloidal dependence of lost ions from hydrogen and deuterium plasmas during the 2005-06 JET restart campaign, will be presented.
nuclei

Directory of Open Access Journals (Sweden)

Minkov N.

2016-01-01

Full Text Available We study the effects of quadrupole-octupole deformations on the energy and magnetic properties of high-K isomeric states in even-even heavy and superheavy nuclei. The neutron two-quasiparticle (2qp isomeric energies and magnetic dipole moments are calculated within a deformed shell model with the Bardeen-Cooper- Schrieffer (BCS pairing interaction over a wide range of quadrupole and octupole deformations. We found that in most cases the magnetic moments exhibit a pronounced sensitivity to the octupole deformation, while the 2qp energies indicate regions of nuclei in which the presence of high-K isomeric states may be associated with the presence of octupole softness or even with octupole deformation. In the present work we also examine the influence of the BCS pairing strength on the energy of the blocked isomer configuration. We show that the formation of 2qp energy minima in the space of quadrupole-octupole and eventually higher multipolarity deformations is a subtle effect depending on nuclear pairing correlations.
Are there multiquark bags in nuclei

International Nuclear Information System (INIS)

Kondratyuk, L.A.; Scmatkov, M.Zh.

1983-01-01

Arguments are presented favouring the idea that multiquark bags do eXist in nuclei. Such hypothesis makes possible to reveal the relationship among three different scopes of phenomena: deep inelastic scattering of leptons by nUclei, large q 2 (where q 2 is a square of momentum transfer) behaviour of the form factors of light nuclei and yield of cumulative proton.s
Electron scattering for exotic nuclei

International Nuclear Information System (INIS)

Suda, T.

2013-01-01

An electron scattering facility is under construction in RIKEN RI Beam Factory, Japan, which is dedicated to the structure studies of short-lived nuclei. This is the world's first and currently only facility of its type. The construction is nearly completed, and the first electron scattering experiment off short-lived nuclei will be carried out in the beginning of next year. The charge density distributions of short-lived nuclei will be precisely determined by elastic electron scattering for the first time. Physics pursued at this facility including future perspectives are explained
The decay of hot nuclei

International Nuclear Information System (INIS)

Moretto, L.G.; Wozniak, G.J.

1988-11-01

The formation of hot compound nuclei in intermediate-energy heavy ion reactions is discussed. The statistical decay of such compound nuclei is responsible for the abundant emission of complex fragments and high energy gamma rays. 43 refs., 23 figs
Thermodynamics of pairing phase transition in nuclei

International Nuclear Information System (INIS)

Karim, Afaque; Ahmad, Shakeb

2014-01-01

The pairing gaps, pairing energy, heat capacity and entropy are calculated within BCS (Bardeen- Cooper-Schrieffer) based quasi particle approach, including thermal fluctuations on pairing field within pairing model for all nuclei (light, medium, heavy and super heavy nuclei). Quasi particles approach in BCS theory was introduced and reformulated to study various properties. For thermodynamic behavior of nuclei at finite temperatures, the anomalous averages of creation and annihilation operators are introduced. It is solved self consistently at finite temperatures to obtain BCS Hamiltonian. After doing unitary transformation, we obtained the Hamiltonian in the diagonal form. Thus, one gets temperature dependence gap parameter and pairing energy for nuclei. Moreover, the energy at finite temperatures is the sum of the condensation energy and the thermal energy of fermionic quasi particles. With the help of BCS Hamiltonian, specific heat, entropy and free energy are calculated for different nuclei. In this paper the gap parameter occupation number and pairing energy as a function of temperature which is important for all the light, medium, heavy and super heavy nuclei is calculated. Moreover, the various thermo dynamical quantities like specific heat, entropy and free energy is also obtained for different nuclei. Thus, the thermodynamics of pairing phase transition in nuclei is studied
On the distribution of quarks in nuclei

International Nuclear Information System (INIS)

Baldin, A.M.; Panebrattsev, V.S.; Stavinskij, V.S.

1984-01-01

On the basis of the data on cumulative proton, deuteron and nuclear fragment production in hadr on-nucleon reactions and deep inelastic muon-nucleon scattering quark distributions in light, intemediate and heavy nuclei have been investigated. Conditions of limiting fragmentation of hadrons and nuclei in the studied processes have been investigated to obtain quark-parton structure functions (Gs 2 ) of the studied hadrons or nuclei. Invariant differential cross sections of π + , π - , K + meson production on aluminium, deuterium and lead nuclei and their dependence on scale variable at the transverse momentum value Psub(T) approximately 0 have been obtained. Properties of structure functions G 2 and behaviour of different nuclei differential cross sections of limiting fragmentation have been investigated. It is concluded that considered regularities testify to the presence of multiquark states in nuclei, different by its structure from nUcleons
Collisions with nuclei

International Nuclear Information System (INIS)

Gulamov, K.G.

1987-01-01

It is well known that interactions of high energy particles with nuclei, owing to possible intranuclear rescatterings, may provide information about the space-time behaviour of the production process. Therefore the main goals of these investigations are related with the attempts to study the space-time process of hadronization of coloured quarks and gluons produced at the initial stage of an interaction to white final state particles and to clarify the influence of composite quark-gluon structure of both the projectile and target on features of the production mechanisms. Since in both the initial and final states of these reactions the authors have strongly interacting multiparticle systems, it is of importance to study the collective properties of these systems. The questions to the point are: what is the degree of collectivization of particles newly produced in collisions with nuclei and what is the influence of the collective nature of a nucleus itself on the production mechanisms, in particular, what are the manifestations of possible multinucleon (multiquark) configurations in nuclei? It is obvious that the reductability of, say, hadron-nucleus (hA) interaction to hadron-nucleon (hN) collisions is directly related to the above problems. Due to time limitations the author discusses here only a few aspects of low p/sub t/ hA interactions which in his opinion are of importance for better understanding of general regularities of collisions with nuclei and for further investigations of the above problems
Spectroscopy of heavy fissionable nuclei

Indian Academy of Sciences (India)

2015-08-05

Aug 5, 2015 ... Nuclei in the actinide chain and beyond are prone to fission owing to ... mass nuclei are typically more difficult, because the intensity is .... j15/2 neutron alignments in a region where shell stablization effects are crucial.
The Ionization Fraction in the Obscuring ``Torus'' of an Active Galactic Nucleus

Science.gov (United States)

Wilson, A. S.; Roy, A. L.; Ulvestad, J. S.; Colbert, E. J. M.; Weaver, K. A.; Braatz, J. A.; Henkel, C.; Matsuoka, M.; Xue, S.; Iyomoto, N.; Okada, K.

1998-10-01

The LINER galaxy NGC 2639 contains a water vapor megamaser, suggesting the presence of a nuclear accretion disk or torus viewed close to edge-on. This galaxy is thus a good candidate for revealing absorption by the torus of any compact nuclear continuum emission. In this paper, we report VLBA radio maps at three frequencies and an ASCA X-ray spectrum obtained to search for free-free and photoelectric absorptions, respectively. The radio observations reveal a compact (~1.3 × 10-5, which is comparable to the theoretical upper limit derived by Neufeld, Maloney, and Conger for X-ray heated molecular gas. The two values may be reconciled if the molecular gas is very dense: nH2>~109 cm-3. The measured ionization fraction is also consistent with the idea that both absorptions occur in a hot (~6000 K), weakly ionized (ionization fraction a few times 10-2) atomic region that may coexist with the warm molecular gas. If this is the case, the absorbing gas is ~1 pc from the nucleus. We rule out the possibility that both absorptions occur in a fully ionized gas near 104 K. If our line of sight passes through more than one phase, the atomic gas probably dominates the free-free absorption, while the molecular gas may dominate the photoelectric absorption.
From heavy nuclei to super-heavy nuclei; Des noyaux lourds aux super-lourds

Energy Technology Data Exchange (ETDEWEB)

Theisen, Ch

2003-01-01

The existence of super-heavy nuclei has been predicted nearly fifty years ago. Due to the strong coulomb repulsion, the stabilisation of these nuclei is possible only through shell effects. The reasons for this fragile stability, as well as the theoretical predictions concerning the position of the island of stability are presented in the first part of this lecture. In the second part, experiments and experimental techniques which have been used to synthesize or search for super-heavy elements are described. Spectroscopic studies performed in very heavy elements are presented in the following section. We close this lecture with techniques that are currently being developed in order to reach the superheavy island and to study the structure of very-heavy nuclei. (author)
Colliding nuclei

International Nuclear Information System (INIS)

Balian, Roger; Remaud, Bernard; Suraud, E.; Durand, Dominique; Tamain, Bernard; Gobbi, A.; Cugnon, J.; Drapier, Olivier; Govaerts, Jan; Prieels, Rene

1995-09-01

This 14. international school Joliot-Curie of nuclear physic deals with nuclei in collision at high energy. Nine lectures are included in the proceedings of this summer school: 1 - From statistical mechanics outside equilibrium to transport equations (Balian, R.); 2 - Modeling of heavy ions reactions (Remaud, B.); 3 - Kinetic equations in heavy ions physics (Suraud, E.); 4 - Colliding nuclei near the Fermi energy (Durand, D.; Tamain, B.); 5 - From the Fermi to the relativistic energy domain: which observable? For which physics? (Gobbi, A.); 6 - Collisions at relativistic and ultra relativistic energies, Theoretical aspects (Cugnon, J.); 7 - Quark-gluon plasma: experimental signatures (Drapier, O.); 8 - Electroweak interaction: a window on physics beyond the standard model (Govaerts, J.); 9 - Symmetry tests in β nuclear process: polarization techniques (Prieels, R.)
Symmetry and Phase Transitions in Nuclei

International Nuclear Information System (INIS)

Iachello, F.

2009-01-01

Phase transitions in nuclei have received considerable attention in recent years, especially after the discovery that, contrary to expectations, systems at the critical point of a phase transition display a simple structure. In this talk, quantum phase transitions (QPT), i.e. phase transitions that occur as a function of a coupling constant that appears in the quantum Hamiltonian, H, describing the system, will be reviewed and experimental evidence for their occurrence in nuclei will be presented. The phase transitions discussed in the talk will be shape phase transitions. Different shapes have different symmetries, classified by the dynamic symmetries of the Interacting Boson Model, U(5), SU(3) and SO(6). Very recently, the concept of Quantum Phase Transitions has been extended to Excited State Quantum Phase Transitions (ESQPT). This extension will be discussed and some evidence for incipient ESQPT in nuclei will be presented. Systems at the critical point of a phase transition are called 'critical systems'. Approximate analytic formulas for energy spectra and other properties of 'critical nuclei', in particular for nuclei at the critical point of the second order U(5)-SO(6) transition, called E(5), and along the line of first order U(5)-SU(3) transitions, called X(5), will be presented. Experimental evidence for 'critical nuclei' will be also shown. Finally, the microscopic derivation of shape phase transitions in nuclei within the framework of density functional methods will be briefly discussed.(author)

Multilayer mirror and foil filter AXUV diode arrays on CDX-U spherical torus

International Nuclear Information System (INIS)

Soukhanovskii, V. A.; Stutman, D.; Iovea, M.; Finkenthal, M.; Moos, H. W.; Munsat, T.; Jones, B.; Hoffman, D.; Kaita, R.; Majeski, R.

2001-01-01

Recent upgrades to CDX-U spherical torus diagnostics include two 10-channel AXUV diode arrays. The multilayer mirror (MLM) array measures the λ150 O VI brightness profile in the poloidal plane using the Mo/B 4 C synthetic multilayer structures as dispersive elements. The foil filter array has a tangential view and is equipped with interchangeable clear aperture, beryllium and titanium filters. This allows measurements of radiated power, O VI or C V radial distributions, respectively. The O VI and C V emissivity and the radiated power profiles are highly peaked. A Neoclassical impurity accumulation mechanism is considered as an explanation. For radiated power measurements in the T e ≤100 eV plasmas, photon energy dependent corrections must be used in order to account for nonlinear AXUV sensitivity in the range E phot ≤20 eV. The arrays are also used for characterization of resistive MHD phenomena, such as the low m modes, saw-tooth oscillations and internal reconnection events. Based on the successful operation of the diagnostics, a new ultra soft x-ray multilayer mirror diode AXUV diode array monitoring the 34 Aa emissivity distribution of C VI will be built and installed on the National Spherical Torus Experiment
Exploration of high harmonic fast wave heating on the National Spherical Torus Experiment

International Nuclear Information System (INIS)

Wilson, J.R.; Bell, R.E.; Bernabei, S.; Bitter, M.; Gates, D.; Hosea, J.; Le Blanc, B.; Medley, S.; Menard, J.; Mueller, D.; Ono, M.; Phillips, C.K.; Rosenberg, A.; Bonoli, P.; Mau, T.K.; Pinsker, R.I.; Raman, R.; Ryan, P.; Swain, D.; Wilgen, J.

2003-01-01

High harmonic fast wave (HHFW) heating has been proposed as a particularly attractive means for plasma heating and current drive in the high beta plasmas that are achievable in spherical torus (ST) devices. The National Spherical Torus Experiment (NSTX) [M. Ono, S. M. Kaye, S. Neumeyer et al., in Proceedings of the 18th IEEE/NPSS Symposium on Fusion Engineering, Albuquerque, 1999 (IEEE, Piscataway, NJ, 1999), p. 53] is such a device. An rf heating system has been installed on the NSTX to explore the physics of HHFW heating, current drive via rf waves and for use as a tool to demonstrate the attractiveness of the ST concept as a fusion device. To date, experiments have demonstrated many of the theoretical predictions for HHFW. In particular, strong wave absorption on electrons over a wide range of plasma parameters and wave parallel phase velocities, wave acceleration of energetic ions, and indications of current drive for directed wave spectra have been observed. In addition HHFW heating has been used to explore the energy transport properties of NSTX plasmas, to create H-mode discharges with a large fraction of bootstrap current and to control the plasma current profile during the early stages of the discharge
Exploration of High Harmonic Fast Wave Heating on the National Spherical Torus Experiment

International Nuclear Information System (INIS)

Wilson, J.R.; Bell, R.E.; Bernabei, S.; Bitter, M.; Bonoli, P.; Gates, D.; Hosea, J.; LeBlanc, B.; Mau, T.K.; Medley, S.; Menard, J.; Mueller, D.; Ono, M.; Phillips, C.K.; Pinsker, R.I.; Raman, R.; Rosenberg, A.; Ryan, P.; Sabbagh, S.; Stutman, D.; Swain, D.; Takase, Y.; Wilgen, J.

2003-01-01

High Harmonic Fast Wave (HHFW) heating has been proposed as a particularly attractive means for plasma heating and current drive in the high-beta plasmas that are achievable in spherical torus (ST) devices. The National Spherical Torus Experiment (NSTX) [Ono, M., Kaye, S.M., Neumeyer, S., et al., Proceedings, 18th IEEE/NPSS Symposium on Fusion Engineering, Albuquerque, 1999, (IEEE, Piscataway, NJ (1999), p. 53.)] is such a device. An radio-frequency (rf) heating system has been installed on NSTX to explore the physics of HHFW heating, current drive via rf waves and for use as a tool to demonstrate the attractiveness of the ST concept as a fusion device. To date, experiments have demonstrated many of the theoretical predictions for HHFW. In particular, strong wave absorption on electrons over a wide range of plasma parameters and wave parallel phase velocities, wave acceleration of energetic ions, and indications of current drive for directed wave spectra have been observed. In addition HHFW heating has been used to explore the energy transport properties of NSTX plasmas, to create H-mode (high-confinement mode) discharges with a large fraction of bootstrap current and to control the plasma current profile during the early stages of the discharge
Deformation and shape coexistence in medium mass nuclei

International Nuclear Information System (INIS)

Meyer, R.A.

1985-01-01

Emerging evidence for deformed structures in medium mass nuclei is reviewed. Included in this review are both nuclei that are ground state symmetric rotors and vibrational nuclei where there are deformed structures at excited energies (shape coexistence). For the first time, Nilsson configurations in odd-odd nuclei within the region of deformation are identified. Shape coexistence in nuclei that abut the medium mass region of deformation is also examined. Recent establishment of a four-particle, four-hole intruder band in the double subshell closure nucleus 96 Zr 56 is presented and its relation to the nuclear vibron model is discussed. Special attention is given to the N=59 nuclei where new data have led to the reanalysis of 97 Sr and 99 Zr and the presence of the [404 9/2] hole intruder state as isomers in these nuclei. The low energy levels of the N=59 nuclei from Z=38 to 50 are compared with recent quadrupole-phonon model calculations that can describe their transition from near-rotational to single closed shell nuclei. The odd-odd N=59 nuclei are discussed in the context of coexisting shape isomers based on the (p[303 5/2]n[404 9/2])2 - configuration. Ongoing in-beam (t,p conversion-electron) multiparameter measurements that have led to the determination of monopole matrix elements for even-even 42 Mo nuclei are presented, and these are compared with initial estimates using IBA-2 calculations that allow mixing of normal and cross subshell excitations. Lastly, evidence for the neutron-proton 3 S 1 force's influence on the level structure of these nuclei is discussed within the context of recent quadrupole-phonon model calculations. (Auth.)
Strength of Coriolis Coupling in actinide nuclei

International Nuclear Information System (INIS)

Peker, L.K.; Rasmussen, J.O.; Hamilton, J.H.

1982-01-01

Coriolis Coupling V/sub cor/ plays an important role in deformed nuclei. V/sub cor/ is proportional to h 2 /J[j (j + 1) -Ω (Ω + 1)]/sup 1/2/ and therefore is particularly significant in the nuclei with large j and low Ω Nilsson levels close to Fermi surface: n(i/sub 13/2/) in A = 150 to 170 rare-earth nuclei and p(i/sub 13/2/) and n(j/sub 15/2/) in A greater than or equal to 224 actinide nuclei. Because of larger j (n(j/sub 15/2/) versus n(i/sub 13/2/)) and smaller deformations (β approx. = 0.22 versus β 0.28) it was reasonable to expect that in actinide nuclei Coriolis effects are stronger than in the rare earth nuclei. Recently it was realized that the strength of observed Coriolis effects depends not only on the genuine Coriolis Coupling but also on the interplay between Coriolis ad pairing forces which leads to an interference between the wave functions of two mixing rotational bands. As a consequence the effective interaction V/sub eff/ of both bands is an oscillating function of the degree of shell filling (or chemical potential lambda F). It was shown that in the rare earth nuclei this interference strongly influenced conclusions about the trends in the Coriolis coupling strength and explained many of the observed band-mixing features (the sharpness of back banding curves, details of the blocking effect etc.). From theoretical analysis it was concluded that in the majority of actinide nuclei the effective interaction V/sub eff/ is strong, and therefore the Coriolis band-mixing have to be very strong. In this paper we would like to demonstrate that contrary to these predictions experimental data suggest that Coriolis band mixing in studied actinide nuclei is relatively weak and possibly significantly weaker than in rare earth nuclei
Monopole transitions in hot nuclei

Energy Technology Data Exchange (ETDEWEB)

Sujkowski, Z. [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)

1994-12-31

Monopole transitions can be a signature of shape changing in a hot, pulsating nucleus (the low energy E0 mode) and/or a measure of the compressibility of finite nuclei (GMR, the breathing mode). Experimental information pertaining to GMR is reviewed. Recipes for deducing the incompressibility modules for infinite nuclear matter from data on GMR are discussed. Astrophysical implications are outlined. The first attempts at locating the GMR strength in moderately hot nuclei are described. Prospects for improving the experimental techniques to make an observation of this strength in selected nuclei unambiguous are discussed. (author). 46 refs, 8 figs.
Monopole transitions in hot nuclei

International Nuclear Information System (INIS)

Sujkowski, Z.

1994-01-01

Monopole transitions can be a signature of shape changing in a hot, pulsating nucleus (the low energy E0 mode) and/or a measure of the compressibility of finite nuclei (GMR, the breathing mode). Experimental information pertaining to GMR is reviewed. Recipes for deducing the incompressibility modules for infinite nuclear matter from data on GMR are discussed. Astrophysical implications are outlined. The first attempts at locating the GMR strength in moderately hot nuclei are described. Prospects for improving the experimental techniques to make an observation of this strength in selected nuclei unambiguous are discussed. (author). 46 refs, 8 figs
Cavitation inception from bubble nuclei

DEFF Research Database (Denmark)

Mørch, Knud Aage

2015-01-01

, and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid....... The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure-time history of the water. A recent model...
Descent of line bundles to GIT quotients of flag varieties by maximal torus

OpenAIRE

Kumar, Shrawan

2007-01-01

Let L be a homogeneous ample line bundle on any flag variety G/P and let T be a maximal torus of G. We prove a general necessary and sufficient condition for L to descend as a line bundle on the GIT quotient of G/P by T. We use this result to explicitly determine exactly which L descend to the GIT quotient for any simple complex algebraic group G and any parabolic subgroup P.
Measurement of The Magnetic Field in a Spherical Torus Plasma via Electron Bernstein Wave Emission Harmonic Overlap

International Nuclear Information System (INIS)

Jones, B.; Taylor, G.; Efthimion, P.C.; Munsat, T.

2004-01-01

Measurement of the magnetic field in a spherical torus by observation of harmonic overlap frequencies in the electron Bernstein wave (EBW) spectrum has been previously suggested [V.F. Shevchenko, Plasma Phys. Reports 26 (2000) 1000]. EBW mode conversion to X-mode radiation has been studied in the Current Drive Experiment-Upgrade spherical torus, [T. Jones, Ph.D. thesis, Princeton University, 1995] with emission measured at blackbody levels [B. Jones et al., Phys. Rev. Lett. 90 (2003) article no. 165001]. Sharp transitions in the thermally emitted EBW spectrum have been observed for the first two harmonic overlaps. These transition frequencies are determined by the magnetic field and electron density at the mode conversion layer in accordance with hot-plasma wave theory. Prospects of extending this measurement to higher harmonics, necessary in order to determine the magnetic field profile, and high beta equilibria are discussed for this proposed magnetic field diagnostic
Electron-microscope study of cloud and fog nuclei

Energy Technology Data Exchange (ETDEWEB)

Ogiwara, S; Okita, T

1952-01-01

Droplets of clouds on a mountain and of fog in an urban area were captured and the form, nature and size of their nuclei were studied by means of an electron-microscope and by a chamber of constant humidity. These nuclei have similar form and nature to the hygroscopic particles in haze and to the artificially produced combustion particles. No sea-salt nuclei were found in our observations, therefore, sea-spray appears to be an insignificant source of condensation nuclei. It was found that both the cloud and the fog nuclei originated in combustion products which were the mixture of hygroscopic and non-hygroscopic substances, and that the greater part of the nuclei did not contain pure sulfuric acid.
Quarks in nuclei

International Nuclear Information System (INIS)

Rho, M.; CEA Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette

1983-01-01

Some features of quark degrees of freedom in nuclei are discussed in the light of recent developments in QCD. The principal aim of this talk is to propose, and give a tentative support to, the motion that one can study through nuclear matter different facets of the vacuum structure implied by quantum chromodynamics (QCD). This will be done using the recent (exciting) results obtained in particle physics, in particular lattice gauge calculations. Relevance of this aspect of problem to quark degrees of freedom as well as meson degrees of freedom in nuclei will be discussed. (orig.)
The dynamics of the nuclei-nuclei interactions at very high energies

International Nuclear Information System (INIS)

Blaizot, J.P.

1988-01-01

The lectures on the dynamics of nuclei-nuclei interactions at very high energies, presented in the Summer School on Nuclear Physics and Particle Physics (1988), are shown. The equation of state of the hadronic matter is analyzed, by means of simple models, and some orders of magnitude can be asserted. The main characteristics of the high energy hadronic interactions are recalled. The basis of the dynamics of the relativistic fluids are given. Applications of this dynamics in the description of the space-time evolution of a plasma, generated by heavy ions collision, are carried out [fr
Differential equations for correlators on the torus: Two-point correlation function of isospin-1 primary fields in the k=3 SU(2) WZW theory

International Nuclear Information System (INIS)

Durganandini, P.

1990-01-01

We systematize the procedure developed by Mathur, Mukhi and Sen to derive differential equations for correlators in rational conformal field theories on the torus in those cases when it is necessary to study not only leading-order behaviour but also the nonleading behaviour of the solutions in the asymptotic limit Imτ→∞, Imz→∞. As an illustration, we derive the differential equation for the two-point correlator of the isospin-1 primary fields in the k=3 SU(2) WZW model on the torus. (orig.)
Electric monopole transitions from low energy excitations in nuclei

CERN Document Server

Wood, J L; De Coster, C; Heyde, Kris L G

1999-01-01

Electric monopole (E0) properties are studied across the entire nuclear mass surface. Besides an introductory discussion of various model results (shell model, geometric vibrational and rotational models, algebraic models), we point out that many of the largest E0 transition strengths, $\\rho^2$(E0), are associated with shape mixing. We discuss in detail the manifestation of E0 transitions and present extensive data for~: single-closed shell nuclei, vibrational nuclei, well-deformed nuclei, nuclei that exhibit sudden ground-state changes, and nuclei that exhibit shape coexistence and intruder states. We also give attention to light nuclei, odd-A nuclei, and illustrate a suggested relation between $\\rho^2$(E0) and isotopic shifts.
Symmetry energy, unstable nuclei and neutron star crusts

Energy Technology Data Exchange (ETDEWEB)

Iida, Kei [Kochi University, Department of Natural Science, Kochi (Japan); RIKEN Nishina Center, Saitama (Japan); Oyamatsu, Kazuhiro [RIKEN Nishina Center, Saitama (Japan); Aichi Shukutoku University, Department of Human Informatics, Aichi (Japan)

2014-02-15

The phenomenological approach to inhomogeneous nuclear matter is useful to describe fundamental properties of atomic nuclei and neutron star crusts in terms of the equation of state of uniform nuclear matter. We review a series of researches that we have developed by following this approach. We start with more than 200 equations of state that are consistent with empirical masses and charge radii of stable nuclei and then apply them to describe matter radii and masses of unstable nuclei, proton elastic scattering and total reaction cross sections off unstable nuclei, and nuclei in neutron star crusts including nuclear pasta. We finally discuss the possibility of constraining the density dependence of the symmetry energy from experiments on unstable nuclei and even observations of quasi-periodic oscillations in giant flares of soft gamma-ray repeaters. (orig.)
BLACK HOLE-NEUTRON STAR MERGERS AND SHORT GAMMA-RAY BURSTS: A RELATIVISTIC TOY MODEL TO ESTIMATE THE MASS OF THE TORUS

International Nuclear Information System (INIS)

Pannarale, Francesco; Tonita, Aaryn; Rezzolla, Luciano

2011-01-01

The merger of a binary system composed of a black hole (BH) and a neutron star (NS) may leave behind a torus of hot, dense matter orbiting around the BH. While numerical-relativity simulations are necessary to simulate this process accurately, they are also computationally expensive and unable at present to cover the large space of possible parameters, which include the relative mass ratio, the stellar compactness, and the BH spin. To mitigate this and provide a first reasonable coverage of the space of parameters, we have developed a method for estimating the mass of the remnant torus from BH-NS mergers. The toy model makes use of an improved relativistic affine model to describe the tidal deformations of an extended tri-axial ellipsoid orbiting around a Kerr BH and measures the mass of the remnant torus by considering which of the fluid particles composing the star are on bound orbits at the time of the tidal disruption. We tune the toy model by using the results of fully general-relativistic simulations obtaining relative precisions of a few percent and use it to investigate the space of parameters extensively. In this way, we find that the torus mass is largest for systems with highly spinning BHs, small stellar compactnesses, and large mass ratios. As an example, tori as massive as M b,tor ≅ 1.33 M sun can be produced for a very extended star with compactness C ≅ 0.1 inspiralling around a BH with dimensionless spin parameter a = 0.85 and mass ratio q ≅ 0.3. However, for a more astrophysically reasonable mass ratio q ≅ 0.14 and a canonical value of the stellar compactness C ≅ 0.145, the toy model sets a considerably smaller upper limit of M b,tor ∼ sun .
Cluster structure in Cf nuclei

International Nuclear Information System (INIS)

Singh, Shailesh K.; Biswal, S.K.; Bhuyan, M.; Patra, S.K.; Gupta, R.K.

2014-01-01

Due to the availability of advance experimental facilities, it is possible to probe the nuclei upto their nucleon level very precisely and analyzed the internal structure which will help us to resolve some mysterious problem of the decay of nuclei. Recently, the relativistic nuclear collision, confirmed the α cluster type structure in the 12 C which is the mile stone for the cluster structure in nuclei. The clustering phenomena in light and intermediate elements in nuclear chart is very interesting. There is a lot of work done by our group in the clustering behaviour of the nuclei. In this paper, the various prospectus of clustering in the isotopes of Cf nucleus including fission state is discussed. Here, 242 Cf isotope for the analysis, which is experimentally known is taken. The relativistic mean field model with well established NL3 parameter set is taken. For getting the exact ground state configuration of the isotopes, the calculation for minimizing the potential energy surface is performed by constraint method. The clustering structure of other Cf isotopes is discussed
Experimental device for in-torus handling - EDITH intermediate report

International Nuclear Information System (INIS)

Suppan, A.; Krieg, R.; Krumm, H.G.; Kuehnapfel, U.; Leinemann, K.; Reim, J.; Woll, J.

1993-10-01

The Experimental Device for In-Torus Handling (EDITH) is based on articulated boom system (ABS), consisting of a support structure, the articulated boom transporter (ABT), the end-effector positioning unit (EEPU) and different end-effectors (EE's). It is the prototype of an in-vessel handling system for NET/ITER. In combination with a Full Scale Mock-up, EDITH is required to demonstrate that maintenance of plasma facing components can be carried out with the anticipated reliability and in time. A further aim of EDITH is to allow testing of the articulated boom components and subassemblies. The testbed EDITH and the Full Scale Mock-up are described. In addition, the performance and results of the commissioning and the qualification are summarized and an outlook is given for future tasks. (orig./HP) [de
Reliability and availability assessments for the next European Torus

International Nuclear Information System (INIS)

Bunde, R.

1988-01-01

To achieve its targets in reasonable time, the Next European Torus (NET) must be operated with considerable reliability and availability (R and A). Therefore, failure modes, effects, and criticality analysis (FMECA) of the overall plant and of its major components is already being performed as the design evolves. The present status of the R and A work is described in four steps: First, the R and A targets envisaged for the NET operation are discussed. Then an FMECA covering the overall plant is described, and a more detailed FMECA of major components is presented concerning the toroidal field coil systeml plasma heating systems; protection, instrumentation, and control systems; first wall and blanket, as well as the cooling system. Finally, the R and A results are compared with the targets, and measures for improvements are given

Abelian projection on the torus for general gauge groups

International Nuclear Information System (INIS)

Ford, C.; Tok, T.; Wipf, A.

1999-01-01

We consider Yang-Mills theories with general gauge groups G and twists of the four-torus. We find consistent boundary conditions for gauge fields in all instanton sectors. An extended abelian projection with respect to the Polyakov loop operator is presented, where A 0 is independent of time and in the Cartan subalgebra. Fundamental domains for the gauge fixed A 0 are constructed for arbitrary gauge groups. In the sectors with non-vanishing instanton number such gauge fixings are necessarily singular. The singularities can be restricted to Dirac strings joining magnetically charged defects. The magnetic charges of these monopoles take their values in the co-root lattice of the gauge group. We relate the magnetic charges of the defects and the windings of suitable Higgs fields about these defects to the instanton number
Critical and shape-unstable nuclei

CERN Document Server

Cailliau, M; Husson, J P; Letessier, J; Mang, H J

1973-01-01

The authors' experimental work on the decay of neutron deficient mercury osmium nuclei, some other studies at ISOLDE (CERN) and their first theoretical analysis show that the nuclei around /sup 186/Pt (Z=78, N=108) are at the limit of spherical, oblate, prolate nuclei, have (the even one) their first 0/sup +/ excited states at very low energy; quasi- rotational bands are associated to these states. The energy of this O/sup +/ state in /sup 186-/Pt deviate from the Kumar value: angular shape instability is not enough to explain this result. The authors look at radial shape and pairing fluctuations. The position of the 4p-4n state must also be known. (0 refs).
Protonic decay of oriented nuclei

International Nuclear Information System (INIS)

Kadmensky, S.G.

2002-01-01

On the basis of the multiparticle theory of protonic decay, the angular distributions of protons emitted by oriented spherical and deformed nuclei in the laboratory frame and in the internal coordinate frame of deformed parent nuclei are constructed with allowance for symmetry with respect to time inversion. It is shown that, because of the deep-subbarrier character of protonic decay, the adiabatic approximation is not applicable to describing the angular distributions of protons emitted by oriented deformed nuclei and that the angular distribution of protons in the laboratory frame does not coincide with that in the internal coordinate frame. It is demonstrated that these angular distributions coincide only if the adiabatic and the semiclassical approximation are simultaneously valid
The Nature of the Torus in the Heavily Obscured AGN Markarian 3: an X-Ray Study

Science.gov (United States)

Guainazzi, M.; Risaliti, G.; Awaki, H.; Arevalo, P.; Bauer, F. E.; Bianchi, S.; Boggs, S.E; Brandt, W. N.; Brightman, M.; Christensen, F. E.;

2016-01-01

In this paper, we report the results of an X-ray monitoring campaign on the heavily obscured Seyfert galaxy, Markarian 3, carried out between the fall of 2014 and the spring of 2015 with NuSTAR, Suzaku and XMMNewton. The hard X-ray spectrum of Markarian 3 is variable on all the time-scales probed by our campaign, down to a few days. The observed continuum variability is due to an intrinsically variable primary continuum seen in transmission through a large, but still Compton-thin column density (N(sub H) approx. 0.8-1.1 x 10(exp 24)/sq cm). If arranged in a spherical-toroidal geometry, the Compton scattering matter has an opening angle approx. 66deg, and is seen at a grazing angle through its upper rim (inclination angle approx. 70deg). We report a possible occultation event during the 2014 campaign. If the torus is constituted by a system of clouds sharing the same column density, this event allows us to constrain their number (17 +/- 5) and individual column density, [approx. (4.9 +/- 1.5) x 10(exp 22)/ sq cm]. The comparison of IR and X-ray spectroscopic results with state-of-the art torus models suggests that at least two-thirds of the X-ray obscuring gas volume might be located within the dust sublimation radius. We report also the discovery of an ionized absorber, characterized by variable resonant absorption lines due to He- and H-like iron. This discovery lends support to the idea that moderate column density absorbers could be due to clouds evaporated at the outer surface of the torus, possibly accelerated by the radiation pressure due to the central AGN emission leaking through the patchy absorber.

Coulomb energy differences in mirror nuclei

International Nuclear Information System (INIS)

Lenzi, Silvia M

2006-01-01

By comparing the excitation energies of analogue states in mirror nuclei, several nuclear structure properties can be studied as a function of the angular momentum up to high spin states. They can be described in the shell model framework by including electromagnetic and nuclear isospin-non-conserving interactions. Calculations for the mirror energy differences in nuclei of the f 7/2 shell are described and compared with recent experimental data. These studies are extended to mirror nuclei in the upper sd and fp shells
Is there chirality in atomic nuclei?

International Nuclear Information System (INIS)

Meng Jie

2009-01-01

Static chiral symmetries are common in nature, for example, the macroscopic spirals of snail shells, the microscopic handedness of certain molecules, and human hands. The concept of chirality in atomic nuclei was first proposed in 1997, and since then many efforts have been made to understand chiral symmetry and its spontaneous breaking in atomic nuclei. Recent theoretical and experimental progress in the verification of chirality in atomic nuclei will be reviewed, together with a discussion of the problems that await to be solved in the future. (authors)
ADHM construction of instantons on the torus

International Nuclear Information System (INIS)

Ford, C.; Pawlowski, J.M.; Tok, T.; Wipf, A.

2001-01-01

We apply the ADHM instanton construction to SU(2) gauge theory on T n xR 4-n for n=1,2,3,4. To do this we regard instantons on T n xR 4-n as periodic (modulo gauge transformations) instantons on R 4 . Since the R 4 topological charge of such instantons is infinite the ADHM algebra takes place on an infinite dimensional linear space. The ADHM matrix M is related to a Weyl operator (with a self-dual background) on the dual torus T-tilde n . We construct the Weyl operator corresponding to the one-instantons on T n xR 4-n . In order to derive the self-dual potential on T n xR 4-n it is necessary to solve a specific Weyl equation. This is a variant of the Nahm transformation. In the case n=2 (i.e., T 2 xR 2 ) we essentially have an Aharonov-Bohm problem on T-tilde 2 . In the one-instanton sector we find that the scale parameter, λ, is bounded above, λ 2 V-tilde 2
Study of the experimental data of multifragmentation of gold and krypton nuclei on interactions with photoemulsion nuclei at high energies

International Nuclear Information System (INIS)

Saleh, Z.A.; Abdel-Hafez, A.

2002-01-01

Results from EMU-01/12 collaboration for the experimental data on multifragmentation of gold residual nuclei created in the interactions with photoemulsion nuclei at the energy of 10.7 GeV/nucleon are presented together with the experimental data on multifragmentation of krypton created on the interactions with photoemulsion nuclei at energy of 0.9 GeV/nucleon. The data are analyzed in the frame of the statistical model of multifragmentation. It is obvious that there are two regimes for nuclear multifragmentation: the former is when less than one-half of nucleons of projectile nucleus are knocked out, the later is when more than one-half of nucleons are knocked out. Residual nuclei with masses close to each other created at different reactions are fragmented practically simultaneously when more than one-half of nucleons of original nuclei are knocked out. These results give an indication that projectiles other than Gold and Krypton may give the same characterization on interaction with emulsion nuclei at high energies
Spectroscopy of very heavy nuclei with a view to study super-heavy nuclei

International Nuclear Information System (INIS)

Khalfallah, F.

2007-08-01

Within the recent years, the spectroscopic study of single particle orbitals of very heavy elements (VHE) has become possible with the development of increasingly efficient experimental setups. This allows us, through nuclear deformation, to access with these deformed nuclei to orbitals situated around the Fermi level in the spherical superheavy elements (SHE) and learn more about the nuclear structure of these nuclei. The aim of this work is the spectroscopic studies of heavy and very heavy elements. Because of the experimental difficulties associated with the fusion reactions in the VHE region, a detailed optimization studies is essential. Simulation of energy loss and angular straggling of these nuclei due to the interaction in the target and to neutron's evaporation was carried out and allowed us to optimize the angular acceptance of the separators according to the target thickness. An extensive survey and exploration in the VHE region was also conducted on the basis of cross section's systematics in the literature and simulations carried out using the statistical code Hivap. In this framework, the possible extension of the range of validity of a set of Hivap parameters was investigated. This work has enabled us to prepare a list of experiments of interest for the production of very heavy nuclei. In this thesis, our work was concentrated on the spectroscopy of the nuclei No 256 et Rf 256 for which two experimental proposals were accepted. The octupole deformations predicted in the actinides region is studied in another part of this thesis, a part witch is dedicated to the gamma spectroscopy of Pa 223 . The data from a new experiment carried out using the Jurogam-Ritu-Great setup are analysed and compared to previous results. They confirm the octupole deformed shape in this nucleus. (author)
Hot nuclei and fragmentation

International Nuclear Information System (INIS)

Guerreau, D.

1993-01-01

A review is made of the present status concerning the production of nuclei above 5 MeV temperature. Considerable progress has been made recently on the understanding of the formation and the fate of such hot nuclei. It appears that the nucleus seems more stable against temperature than predicted by static calculations. However, the occurrence of multifragment production at high excitation energies is now well established. The various experimental features of the fragmentation process are discussed. (author) 59 refs., 12 figs
Major new sources of biological ice nuclei

Science.gov (United States)

Moffett, B. F.; Hill, T.; Henderson-Begg, S. K.

2009-12-01

Almost all research on biological ice nucleation has focussed on a limited number of bacteria. Here we characterise several major new sources of biogenic ice nuclei. These include mosses, hornworts, liverworts and cyanobacteria. Ice nucleation in the eukaryotic bryophytes appears to be ubiquitous. The temperature at which these organisms nucleate is that at which the difference in vapour pressure over ice and water is at or close to its maximum. At these temperatures (-8 to -18 degrees C) ice will grow at the expense of supercooled water. These organisms are dependent for their water on occult precipitation - fog, dew and cloudwater which by its nature is not collected in conventional rain gauges. Therefore we suggest that these organism produce ice nuclei as a water harvesting mechanism. Since the same mechanism would also drive the Bergeron-Findeisen process, and as moss is known to become airborne, these nuclei may have a role in the initiation of precipitation. The properties of these ice nuclei are very different from the well characterised bacterial nuclei. We will also present DNA sequence data showing that, although related, the proteins responsible are only very distantly related to the classical bacterial ice nuclei.
Heavy ion beam study of potential formation in bumpy torus plasma

International Nuclear Information System (INIS)

Takasugi, Keiichi.

1985-01-01

A heavy ion beam probe is constructed for the study of plasma confinement in Nagoya Bumpy Torus (NBT-1/1M). The measurement of the local plasma potential as well as the electron density profile is possible with good spatial (1 -- 2 cm) and temporal (-- 1 msec) resolutions. The feedback controlled detection technique and the time resolved fast detection technique are coupled to use, which enables us to measure local potential reliably even in the pulsed experiments. The process of the devlopment of concentric equipotential surface is observed. The cold and collisional plasma in bumpy torus is not in the equilibrium (C-mode), and the vertically polarized potential profile is produced by the toroidal drift. With the growth of warm collisionless electron component, the polarization is poloidally short-circuited, and the concentric equipotential surface is developed. The concentric negative potential well and its positive rim are observed in the standard operation. The position of the potential boundary (rim) moves with the second harmonic ECRH zone at the midplane of each mirror section, where the hot electron ring exists. The rim potential is formed by the direct loss of warm electrons. It is confirmed that the core electron heating is essential for the negative potential formation. The potential depth is much larger than the ion temperature Tsub(i), and cannot be explained by the existing neoclassical theory. A stable positive potential is observed near T-M transition. The positive potential is also observed in the ion heated plasma. Relating to the growth of the high energy component, the potential formation due to direct loss process is discussed. (author)
Structure and clusters of light unstable nuclei

International Nuclear Information System (INIS)

En'yo, Yoshiko

2010-01-01

As it is known, cluster structures are often observed in light nuclei. In the recent evolution of unstable nuclear research (on nuclei having unbalanced number of neutron and proton) further new types of clusters are coming to be revealed. In this report, structures of light unstable nuclei and some of the theoretical models to describe them are reviewed. The following topics are picked up. 1. Cluster structure and theoretical models, 2. Cluster structure of unstable nuclei (low excited state). 3. Cluster structure of neutron excess beryllium isotopes. 4. Cluster gas like state in C isotope. 5. Dineutron structure of He isotopes. Numbers of strange nuclear structures of light nuclei are illustrated. Antisymmetrized molecular dynamics (AMD) is the recently developed theoretical framework which has been successfully used in heavy ion reactions and nuclear structure studies. Successful application of AMD to the isotopes of Be, B and C are illustrated. (S. Funahashi)
Perturbative many-body approaches to finite nuclei

International Nuclear Information System (INIS)

Hjort-Jensen, M.; Engeland, T.; Holt, A.; Osnes, E.

1992-06-01

In this work the authors discuss various approaches to the effective interaction appropriate for finite nuclei. The methods reviewed are the folded-diagram method of Kuo and co-workers and the summation of the folded diagrams as advocated by Lee and Suzuki. Examples of applications to sd-shell nuclei from previous works are discussed together with hitherto unpublished results for nuclei in pf-shell. Since the method of Lee and Suzuki is found to yield the best converged results, this method is applied to calculate the effective interaction for nuclei in the pf-shell. For the calculation of the effective interaction, three recent versions of the Bonn meson-exchange potential model have been used. These versions are fitted to the same set of data and differ only in the strength of the tensor force. The importance of the latter for finite nuclei is discussed. 67 refs., 17 figs., 7 tabs
A new spin-oriented nuclei facility: POLAREX

Directory of Open Access Journals (Sweden)

Etilé A.

2014-03-01

Full Text Available Using the On-Line Nuclear Orientation method, POLAREX (POLARization of EXotic nuclei is a new facility allowing to study the anisotropic decay of spin-oriented nuclei. Based on the combination of on-line implantation of radioactive nuclei with Low Temperature Nuclear Orientation technique and Nuclear Magnetic Resonance, POLAREX allows to measure nuclear electromagnetic moments and ground-state spins, in the aim to get information about the wave function composition of the nuclear state. Polarized nuclei can also be used to study fundamental interactions involving nuclear β-decay asymmetries. The POLAREX infrastructure will be installed at Accélérateur Linéaire auprés du Tandem d’Orsay in order to study neutron-rich nuclei, some of which have not been studied yet. Will be presented here, all the possibilities of this new facility and a non exhaustive scientific program.
Formation and decay of hot nuclei

International Nuclear Information System (INIS)

Tamain, B.

1992-09-01

The mechanisms involved in hot nuclei formation and decay and their eventual connexion with fundamental properties of nuclear matter are discussed, i.e. its equation of state is considered. After a brief review of the reactions in which hot nuclei can be formed, the variables which are used to describe them, the corresponding theoretical descriptions and their limits when extreme states are reached are discussed. Experimental evidences for hot nuclei formation are presented, with the corresponding decay properties used as signatures. (R.P.) 64 refs.; 25 figs.; 2 tabs
Elusive active galactic nuclei

Science.gov (United States)

Maiolino, R.; Comastri, A.; Gilli, R.; Nagar, N. M.; Bianchi, S.; Böker, T.; Colbert, E.; Krabbe, A.; Marconi, A.; Matt, G.; Salvati, M.

2003-10-01

A fraction of active galactic nuclei do not show the classical Seyfert-type signatures in their optical spectra, i.e. they are optically `elusive'. X-ray observations are an optimal tool to identify this class of objects. We combine new Chandra observations with archival X-ray data in order to obtain a first estimate of the fraction of elusive active galactic nuclei (AGN) in local galaxies and to constrain their nature. Our results suggest that elusive AGN have a local density comparable to or even higher than optically classified Seyfert nuclei. Most elusive AGN are heavily absorbed in the X-rays, with gas column densities exceeding 1024 cm-2, suggesting that their peculiar nature is associated with obscuration. It is likely that in elusive AGN the nuclear UV source is completely embedded and the ionizing photons cannot escape, which prevents the formation of a classical narrow-line region. Elusive AGN may contribute significantly to the 30-keV bump of the X-ray background.
Nuclei quadrupole coupling constants in diatomic molecule

International Nuclear Information System (INIS)

Ivanov, A.I.; Rebane, T.K.

1993-01-01

An approximate relationship between the constants of quadrupole interaction of nuclei in a two-atom molecule is found. It enabled to establish proportionality of oscillatory-rotation corrections to these constants for both nuclei in the molecule. Similar results were obtained for the factors of electrical dipole-quadrupole screening of nuclei. Applicability of these relationships is proven by the example of lithium deuteride molecule. 4 refs., 1 tab
Nuclei at the limits of particle stability

International Nuclear Information System (INIS)

Mueller, A.C.

1993-01-01

The properties and synthesis of nuclei at the limits of particle stability are reviewed. Nuclear reactions were induced and studied by means of the 'exotic' nuclear beams, i.e. beams of radioactive drip-line nuclei. The beams are mostly generated in heavy-ion projectile fragmentation. The cases of both neutron-rich and proton-rich nuclei are discussed. (K.A.) 270 refs.; 13 figs.; 1 tab
DUST IN THE POLAR REGION AS A MAJOR CONTRIBUTOR TO THE INFRARED EMISSION OF ACTIVE GALACTIC NUCLEI

Energy Technology Data Exchange (ETDEWEB)

Hoenig, S. F.; Antonucci, R. [Department of Physics, University of California in Santa Barbara, Broida Hall, Santa Barbara, CA 93109 (United States); Kishimoto, M.; Tristram, K. R. W.; Asmus, D.; Weigelt, G. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Prieto, M. A. [Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife (Spain); Gandhi, P. [Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Burtscher, L. [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrae, D-85748 Garching (Germany); Duschl, W. J., E-mail: shoenig@physics.ucsb.edu [Institut fuer Theoretische Physik und Astrophysik, Christian-Albrechts-Universitaet zu Kiel, Leibnizstr. 15, D-24098, Kiel (Germany)

2013-07-10

Dust around active galactic nuclei (AGNs) is distributed over a wide range of spatial scales and can be observed in the infrared (IR). It is generally assumed that the distribution on parsec scales forms a geometrically and optically thick entity in the equatorial plane around the accretion disk and broad-line region-dubbed {sup d}ust torus{sup -}that emits the bulk of the subarcsecond-scale IR emission and gives rise to orientation-dependent obscuration. However, recent IR interferometry studies with unprecedented position angle (P.A.) and baseline coverage on these small scales in two obscured (type 2) AGNs have revealed that the majority of the mid-IR emission in these objects is elongated in the polar direction. These observations are difficult to reconcile with the standard interpretation that most of the parsec-scale mid-IR emission in AGNs originate from the torus and challenges the justification of using simple torus models to model the broadband IR emission. Here, we report detailed interferometry observations of the unobscured (type 1) AGN in NGC 3783 that allow us to constrain the size, elongation, and direction of the mid-IR emission with high accuracy. The mid-IR emission is characterized by a strong elongation toward position angle P.A. -52 Degree-Sign , closely aligned with the polar axis (P.A. -45 Degree-Sign ). We determine half-light radii along the major and minor axes at 12.5 {mu}m of (20.0 {+-} 3.0) mas Multiplication-Sign (6.7 {+-} 1.0) mas or (4.23 {+-} 0.63) pc Multiplication-Sign (1.42 {+-} 0.21) pc, which corresponds to intrinsically scaled sizes of (69.4 {+-} 10.8) r{sub in} Multiplication-Sign (23.3 {+-} 3.5) r{sub in} for the inner dust radius of r{sub in} = 0.061 pc as inferred from near-IR reverberation mapping. This implies an axis ratio of 3:1, with about 60%-90% of the 8-13 {mu}m emission associated with the polar-elongated component. It is quite likely that the hot-dust emission as recently resolved by near-IR interferometry is

Automated Segmentation of Nuclei in Breast Cancer Histopathology Images.

Science.gov (United States)

Paramanandam, Maqlin; O'Byrne, Michael; Ghosh, Bidisha; Mammen, Joy John; Manipadam, Marie Therese; Thamburaj, Robinson; Pakrashi, Vikram

2016-01-01

The process of Nuclei detection in high-grade breast cancer images is quite challenging in the case of image processing techniques due to certain heterogeneous characteristics of cancer nuclei such as enlarged and irregularly shaped nuclei, highly coarse chromatin marginalized to the nuclei periphery and visible nucleoli. Recent reviews state that existing techniques show appreciable segmentation accuracy on breast histopathology images whose nuclei are dispersed and regular in texture and shape; however, typical cancer nuclei are often clustered and have irregular texture and shape properties. This paper proposes a novel segmentation algorithm for detecting individual nuclei from Hematoxylin and Eosin (H&E) stained breast histopathology images. This detection framework estimates a nuclei saliency map using tensor voting followed by boundary extraction of the nuclei on the saliency map using a Loopy Back Propagation (LBP) algorithm on a Markov Random Field (MRF). The method was tested on both whole-slide images and frames of breast cancer histopathology images. Experimental results demonstrate high segmentation performance with efficient precision, recall and dice-coefficient rates, upon testing high-grade breast cancer images containing several thousand nuclei. In addition to the optimal performance on the highly complex images presented in this paper, this method also gave appreciable results in comparison with two recently published methods-Wienert et al. (2012) and Veta et al. (2013), which were tested using their own datasets.
Automated Segmentation of Nuclei in Breast Cancer Histopathology Images.

Directory of Open Access Journals (Sweden)

Maqlin Paramanandam

Full Text Available The process of Nuclei detection in high-grade breast cancer images is quite challenging in the case of image processing techniques due to certain heterogeneous characteristics of cancer nuclei such as enlarged and irregularly shaped nuclei, highly coarse chromatin marginalized to the nuclei periphery and visible nucleoli. Recent reviews state that existing techniques show appreciable segmentation accuracy on breast histopathology images whose nuclei are dispersed and regular in texture and shape; however, typical cancer nuclei are often clustered and have irregular texture and shape properties. This paper proposes a novel segmentation algorithm for detecting individual nuclei from Hematoxylin and Eosin (H&E stained breast histopathology images. This detection framework estimates a nuclei saliency map using tensor voting followed by boundary extraction of the nuclei on the saliency map using a Loopy Back Propagation (LBP algorithm on a Markov Random Field (MRF. The method was tested on both whole-slide images and frames of breast cancer histopathology images. Experimental results demonstrate high segmentation performance with efficient precision, recall and dice-coefficient rates, upon testing high-grade breast cancer images containing several thousand nuclei. In addition to the optimal performance on the highly complex images presented in this paper, this method also gave appreciable results in comparison with two recently published methods-Wienert et al. (2012 and Veta et al. (2013, which were tested using their own datasets.
α decay chains in 271-294115 superheavy nuclei

International Nuclear Information System (INIS)

Santhosh, K. P.; Priyanka, B.; Joseph, Jayesh George; Sahadevan, Sabina

2011-01-01

α decay of 271-294 115 superheavy nuclei is studied using the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The predicted α half-lives of 287 115 and 288 115 nuclei and their decay products are in good agreement with experimental values. Comparison of α and spontaneous fission half-lives predicts four-α chains and three-α chains, respectively, from 287 115 and 288 115 nuclei and are in agreement with experimental observation. Our study predicts two-α chains from 273,274,289 115, three-α chains from 275 115, and four-α chains consistently from 284,285,286 115 nuclei. These observations will be useful for further experimental investigation in this region.
Organization of the auditory brainstem in a lizard, Gekko gecko. I. Auditory nerve, cochlear nuclei, and superior olivary nuclei.

Science.gov (United States)

Tang, Yezhong; Christensen-Dalsgaard, Jakob; Carr, Catherine E

2012-06-01

We used tract tracing to reveal the connections of the auditory brainstem in the Tokay gecko (Gekko gecko). The auditory nerve has two divisions, a rostroventrally directed projection of mid- to high best-frequency fibers to the nucleus angularis (NA) and a more dorsal and caudal projection of low to middle best-frequency fibers that bifurcate to project to both the NA and the nucleus magnocellularis (NM). The projection to NM formed large somatic terminals and bouton terminals. NM projected bilaterally to the second-order nucleus laminaris (NL), such that the ipsilateral projection innervated the dorsal NL neuropil, whereas the contralateral projection crossed the midline and innervated the ventral dendrites of NL neurons. Neurons in NL were generally bitufted, with dorsoventrally oriented dendrites. NL projected to the contralateral torus semicircularis and to the contralateral ventral superior olive (SOv). NA projected to ipsilateral dorsal superior olive (SOd), sent a major projection to the contralateral SOv, and projected to torus semicircularis. The SOd projected to the contralateral SOv, which projected back to the ipsilateral NM, NL, and NA. These results suggest homologous patterns of auditory connections in lizards and archosaurs but also different processing of low- and high-frequency information in the brainstem. Copyright © 2011 Wiley Periodicals, Inc.
Physics Basis for a Spherical Torus Power Plant

International Nuclear Information System (INIS)

Kessel, C.E.; Menard, J.; Jardin, S.C.; Mau, T.K.

1999-01-01

The spherical torus, or low-aspect-ratio tokamak, is considered as the basis for a fusion power plant. A special class of wall-stabilized high-beta high-bootstrap fraction low-aspect-ratio tokamak equilibrium are analyzed with respect to MHD stability, bootstrap current and external current drive, poloidal field system requirements, power and particle exhaust and plasma operating regime. Overall systems optimization leads to a choice of aspect ratio A = 1:6, plasma elongation kappa = 3:4, and triangularity delta = 0:64. The design value for the plasma toroidal beta is 50%, corresponding to beta N = 7:4, which is 10% below the ideal stability limit. The bootstrap fraction of 99% greatly alleviates the current drive requirements, which are met by tangential neutral beam injection. The design is such that 45% of the thermal power is radiated in the plasma by Bremsstrahlung and trace Krypton, with Neon in the scrapeoff layer radiating the remainder
I/O routing in a multidimensional torus network

Science.gov (United States)

Chen, Dong; Eisley, Noel A.; Heidelberger, Philip

2018-04-24

A method, system and computer program product are disclosed for routing data packet in a computing system comprising a multidimensional torus compute node network including a multitude of compute nodes, and an I/O node network including a plurality of I/O nodes. In one embodiment, the method comprises assigning to each of the data packets a destination address identifying one of the compute nodes; providing each of the data packets with a toio value; routing the data packets through the compute node network to the destination addresses of the data packets; and when each of the data packets reaches the destination address assigned to said each data packet, routing said each data packet to one of the I/O nodes if the toio value of said each data packet is a specified value. In one embodiment, each of the data packets is also provided with an ioreturn value used to route the data packets through the compute node network.
A Widespread, Clumpy Starburst in the Isolated Ongoing Dwarf Galaxy Merger dm1647+21

Energy Technology Data Exchange (ETDEWEB)

Privon, G. C. [Instituto de Astrofśica, Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22 (Chile); Stierwalt, S.; Johnson, K. E.; Kallivayalil, N.; Liss, S. [Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904 (United States); Patton, D. R. [Department of Physics and Astronomy, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2 (Canada); Besla, G. [Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Pearson, S.; Putman, M., E-mail: gprivon@astro.puc.cl [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Collaboration: TiNy Titans

2017-09-01

Interactions between pairs of isolated dwarf galaxies provide a critical window into low-mass hierarchical, gas-dominated galaxy assembly and the build-up of stellar mass in low-metallicity systems. We present the first Very Large Telescope/Multi Unit Spectroscopic Explorer (VLT/MUSE) optical integral field unit (IFU) observations of the interacting dwarf pair dm1647+21 selected from the TiNy Titans survey. The H α emission is widespread and corresponds to a total unobscured star formation rate (SFR) of 0.44 M {sub ⊙} yr{sup −1}, which is 2.7 times higher than the SFR inferred from Sloan Digital Sky Survey (SDSS) data. The implied specific SFR (sSFR) for the system is elevated by more than an order of magnitude above non-interacting dwarfs in the same mass range. This increase is dominated by the lower-mass galaxy, which has a sSFR enhancement of >50. Examining the spatially resolved maps of classic optical line diagnostics, we find that the interstellar medium (ISM) excitation can be fully explained by star formation. The velocity field of the ionized gas is not consistent with simple rotation. Dynamical simulations indicate that the irregular velocity field and the stellar structure is consistent with the identification of this system as an ongoing interaction between two dwarf galaxies. The widespread, clumpy enhancements in the star formation in this system point to important differences in the effect of mergers on dwarf galaxies, compared to massive galaxies; rather than the funneling of gas to the nucleus and giving rise to a nuclear starburst, starbursts in low-mass galaxy mergers may be triggered by large-scale ISM compression, and thus may be more distributed.
Nuclear Computational Low Energy Initiative (NUCLEI)

Energy Technology Data Exchange (ETDEWEB)

Reddy, Sanjay K. [University of Washington

2017-08-14

This is the final report for University of Washington for the NUCLEI SciDAC-3. The NUCLEI -project, as defined by the scope of work, will develop, implement and run codes for large-scale computations of many topics in low-energy nuclear physics. Physics to be studied include the properties of nuclei and nuclear decays, nuclear structure and reactions, and the properties of nuclear matter. The computational techniques to be used include Quantum Monte Carlo, Configuration Interaction, Coupled Cluster, and Density Functional methods. The research program will emphasize areas of high interest to current and possible future DOE nuclear physics facilities, including ATLAS and FRIB (nuclear structure and reactions, and nuclear astrophysics), TJNAF (neutron distributions in nuclei, few body systems, and electroweak processes), NIF (thermonuclear reactions), MAJORANA and FNPB (neutrino-less double-beta decay and physics beyond the Standard Model), and LANSCE (fission studies).
Laser method of free atom nuclei orientation

International Nuclear Information System (INIS)

Barabanov, A.L.

1987-01-01

Orientation process of free atom (atoms in beams) nuclei, scattering quanta of circularly polarized laser radiation is considered. A method for the evaluation of nuclei orientation parameters is developed. It is shown that in the process of pumping between the ground and first excited atomic states with electron shell spins J 1 and J 2 , so that J 2 = J 1 + 1, a complete orientation of nuclei can be attained
Possible existence of backbending in actinide nuclei

International Nuclear Information System (INIS)

Dudek, J.; Nazarewicz, W.; Szymanski, Z.

1982-01-01

The possibilities for the backbending effect to occur in actinide nuclei are studied using the pairing-self-consistent independent quasiparticle method. The Hamiltonian used is that of the deformed Woods-Saxon potential plus monopole pairing term. The results of the calculations explain why there is no backbending in most actinide nuclei and simultaneously suggest that in some light neutron deficient nuclei around Th and 22 Ra a backbending effect may occur
Numerical model for radial transport in the ELMO Bumpy Torus

International Nuclear Information System (INIS)

Jaeger, E.F.; Hedrick, C.L.

1977-11-01

Neutral and charged particle densities and temperatures are calculated as functions of radius for the toroidal plasma in the ELMO Bumpy Torus (EBT) experiment. Energy dependent ionization and charge-exchange rates, ambipolar diffusion, and self-consistent radial electric field profiles are included. Variation in magnetic field due to finite plasma pressure, effects of energetic electron rings, and transport due to drift waves and magnetic field errors are neglected. Diffusion is assumed to be neoclassical with enhanced losses at low collisionalities. The model reproduces many of the observed features of EBT operation in the quiescent toroidal (T) mode. The self-consistently calculated electric field is everywhere positive (not as in experiments) unless enhanced electron collisionality is included. Solutions for advanced EBT's are obtained and confinement parameters predicted
Quadratic rational rotations of the torus and dual lattice maps

CERN Document Server

Kouptsov, K L; Vivaldi, F

2002-01-01

We develop a general formalism for computed-assisted proofs concerning the orbit structure of certain non ergodic piecewise affine maps of the torus, whose eigenvalues are roots of unity. For a specific class of maps, we prove that if the trace is a quadratic irrational (the simplest nontrivial case, comprising 8 maps), then the periodic orbits are organized into finitely many renormalizable families, with exponentially increasing period, plus a finite number of exceptional families. The proof is based on exact computations with algebraic numbers, where units play the role of scaling parameters. Exploiting a duality existing between these maps and lattice maps representing rounded-off planar rotations, we establish the global periodicity of the latter systems, for a set of orbits of full density.
Collisions between complex atomic nuclei

International Nuclear Information System (INIS)

Vaagen, J. S.

1977-08-01

The use of heavy ion accelerators in the study of nuclear structure and states is reviewed. The reactions discussed are the quasielastic reactions in which small amounts of energy and few particles are exchanged between the colliding nuclei. The development of heavy ion accelerators is also discussed, as well as detection equipment. Exotic phenomena, principally the possible existence of superheavy nuclei, are also treated. (JIW)
Transient waveform acquisition system for the ELMO Bumpy Torus

International Nuclear Information System (INIS)

Young, K.G.; Burris, R.D.; Hillis, D.H.; Overbey, D.R.

1984-10-01

The transient waveform system described in this report is designed to acquire analog waveforms from the ELMO Bumpy Torus (EBT) diagnostic experiments. Pressure, density, synchrotron radiation, etc., are acquired and digitized with a Kinetic Systems TR812 transient recorder and associated modules located in a CAMAC crate. The system can simultaneously acquire, display, and transmit sets of data consisting of identification parameters and up to 1024 data points for 1 to 64 input signals (frequency range = 0.01 pulse/s to 100 kHz) of data every one or more minutes; thus, it can run continuously without operator intervention. The data are taken on a VAX 11/780 and transmitted to a data base on a DECSystem-10. To aid the programmer in making future modifications to the system, detailed documentation using the Yourdon structural methods has been given
Bound states of Θ+ in nuclei

International Nuclear Information System (INIS)

Oset, E.; Cabrera, D.; Li, Q.B.; Magas, V.K.; Vicente Vacas, M.J.

2005-01-01

We study the binding energy and the width of the Θ + in nuclei, associated to the KN and KπN components. The first one leads to negligible contributions while the second one leads to a sizeable attraction, enough to bind the Θ + in nuclei. Pauli blocking and binding effects on the KN decay reduce considerably the Θ + decay width in nuclei and medium effects associated to the KπN component also lead to a very small width, as a consequence of which one finds separation between the bound levels considerably larger than the width of the states
Chaos in nuclei: Theory and experiment

Science.gov (United States)

Muñoz, L.; Molina, R. A.; Gómez, J. M. G.

2018-05-01

During the last three decades the quest for chaos in nuclei has been quite intensive, both with theoretical calculations using nuclear models and with detailed analyses of experimental data. In this paper we outline the concept and characteristics of quantum chaos in two different approaches, the random matrix theory fluctuations and the time series fluctuations. Then we discuss the theoretical and experimental evidence of chaos in nuclei. Theoretical calculations, especially shell-model calculations, have shown a strongly chaotic behavior of bound states in regions of high level density. The analysis of experimental data has shown a strongly chaotic behavior of nuclear resonances just above the one-nucleon emission threshold. For bound states, combining experimental data of a large number of nuclei, a tendency towards chaotic motion is observed in spherical nuclei, while deformed nuclei exhibit a more regular behavior associated to the collective motion. On the other hand, it had never been possible to observe chaos in the experimental bound energy levels of any single nucleus. However, the complete experimental spectrum of the first 151 states up to excitation energies of 6.20 MeV in the 208Pb nucleus have been recently identified and the analysis of its spectral fluctuations clearly shows the existence of chaotic motion.
Particles and nuclei, letters

International Nuclear Information System (INIS)

2001-01-01

The present collection of letters from JINR, Dubna, contains seven separate records on physics from extra dimensions, new physics in the new millennium with GENIUS: double beta decay, dark matter, solar neutrinos, the (μ - , e + ) conversion in nuclei mediated by light Majorana neutrinos, exotic muon-to-positron conversion in nuclei: partial transition sum evaluation by using shell model, solar neutrino problem accounting for self consistent magnetohydrodynamics solution for solar magnetic fields, first neutrino observations from the Sudbury neutrino observatory and status report on BOREXINO and results of the muon-background measurements at CERN
Particles and nuclei, letters

International Nuclear Information System (INIS)

2002-01-01

The present collection of letters from JINR, Dubna, contains seven separate records on kinematic separation and mass analysis of heavy recoiling nuclei, dynamical effects prior to heavy ion fusion, VACTIV-DELPHI graphical dialog based program for the analysis of gamma-ray spectra, irradiation of nuclear emulsions in relativistic beams of 6 He and 3 H nuclei, optical and structural investigations of PLZT x/65/35 (x = 4, 8 %) ferroelectric ceramics irradiated by a high-current pulsed electron beam, the oscillating charge and first evidence for neutrinoless double beta decay
Weak interactions with nuclei

International Nuclear Information System (INIS)

Walecka, J.D.

1983-01-01

Nuclei provide systems where the strong, electomagnetic, and weak interactions are all present. The current picture of the strong interactions is based on quarks and quantum chromodynamics (QCD). The symmetry structure of this theory is SU(3)/sub C/ x SU(2)/sub W/ x U(1)/sub W/. The electroweak interactions in nuclei can be used to probe this structure. Semileptonic weak interactions are considered. The processes under consideration include beta decay, neutrino scattering and weak neutral-current interactions. The starting point in the analysis is the effective Lagrangian of the Standard Model
Reentrainment of radioactive nuclei from filters

International Nuclear Information System (INIS)

Dincklage, R.-D. von

1982-01-01

The possible relevance of atomic phenomena for the reentrainment of radioactive nuclei is discussed. The considerations are based on the coulombic fragmentation mechanism. Nuclei of potential interest in reprocessing technology are identified. Future experiments have been shown to be of definite need in this field. (author)

On the occurrence of nuclei in mature sieve elements.

Science.gov (United States)

Event, R F; Davis, J D; Tucker, C M; Alfieri, F J

1970-12-01

The secondary phloem of 3 species of the Taxodiaceae and 13 species of woody dicotyledons was examined for the occurrence of nuclei in mature sieve elements. Nuclei were found in all mature sieve cells of Metasequoia glyptostroboides, Sequoia sempervirens and Taxodium distichum, and in some mature sieve-tube members in 12 of the 13 species of woody dicotyledons. Except for nuclei of sieve cells undergoing cessation of function, the nuclei in mature sieve cells of M. glyptostroboides, S. sempervirens and T. distichum were normal in appearance. The occurrence and morphology of nuclei in mature sieve-tube members of the woody dicotyledons were quite variable. Only 3 species, Robinia pseudoacacia, Ulmus americana and Vitis riparia, contained some mature sieve elements with apparently normal nuclei.
Nuclear-physical investigations with oriented nuclei and polarized neutrons

International Nuclear Information System (INIS)

Alfimenkov, V.P.; Pikel'ner, L.B.; Sharapov, Eh.I.

1980-01-01

Several experiments with oriented nuclei and polarized neutrons are considered, as well as some methods of polarization of neutrons and nuclei. Experiments on the study of spin dependence of neutron cross sections for fissionable and nonfissionable nuclei interaction of polarized neutrons with polarized nuclei as well as measurement of magnetic momenta of compound-states of rare-earth nuclei. Described are some investigations with thermal neutrons: study on spin dependence of neutron scattering length with nuclei and gamma radiation of neutron radiation capture. Difficulties of production of high-intensive polarized neutron beams and construction of oriented targets are noted. Neutron polarization by transmission of them through a polarized proton target is the most universal method (out of existing methods) in the energy range under consideration [ru
Suppression of tilting instability of a compact torus by energetic particle beams

International Nuclear Information System (INIS)

Nomura, Yasuyuki.

1984-11-01

It is shown that the tilting instability of a compact torus can be suppressed by toroidally circulating energetic particle beams. The stabilizing mechanism is based on the properties of the forced oscillation in the motion of beam particles in a plasma ring. The required beam current for the stabilization is estimated to be sufficiently small compared to the plasma current in the case that the angular velocity of beam particles is close to the betatron frequency. This stabilizing method is applied to a field reversed configuration. Effects of the plasma surface current and beam divergences are also examined. (author)
Plasmafysica - een nieuwe positiebepaling

NARCIS (Netherlands)

Schram, D.C.; Kuperus, M.; Sluijter, F.W.

1982-01-01

Reviews recent developments in plasma physics, with special reference to the prospect of fusion of light atomic nuclei. A table summarises properties of low-temperature plasmas. The Joint European Torus, MHD generators, INTOR and special applications in atomic physics and astrophysics are discussed
DNA Measurement of Overlapping Cell Nuclei in Thick Tissue Sections

Directory of Open Access Journals (Sweden)

Liang Ji

1997-01-01

Full Text Available The paper describes an improved image analysis procedure for measuring the DNA content of cell nuclei in thick sections of liver tissue by absorption densitometry. Whereas previous methods only permitted the analysis of isolated nuclei, the new technique enables both isolated and overlapping nuclei to be measured. A 3D segmentation procedure determines whether each object is an isolated nucleus or a pair of overlapping nuclei; in the latter case the combined optical density is redistributed to the individual nuclei. A selection procedure ensures that only complete nuclei are measured.
Single Particle Entropy in Heated Nuclei

International Nuclear Information System (INIS)

Guttormsen, M.; Chankova, R.; Hjorth-Jensen, M.; Rekstad, J.; Siem, S.; Sunde, A. C.; Syed, N. U. H.; Agvaanluvsan, U.; Schiller, A.; Voinov, A.

2006-01-01

The thermal motion of single particles represents the largest contribution to level density (or entropy) in atomic nuclei. The concept of single particle entropy is presented and shown to be an approximate extensive (additive) quantity for mid-shell nuclei. A few applications of single particle entropy are demonstrated
Relativistic exotic nuclei as projectile beams. New perspectives of studies on the properties of nuclei

International Nuclear Information System (INIS)

Geissel, H.

1997-03-01

Examinations of the production cross-sections and the kinematics permitted refinement of model concepts of the peripheral reactions in exotic nuclei at energies from 100 to 1000 A MeV. Due to the strong selectivity and resolution achieved it was possible to discover a large number of novel isotopes at the fragment separator FRS, despite the relatively low projectile beam intensities of the SIS. The two twice magic nuclei found, Ni 78 and Sn 100, are particularly interesting, as they could not be measured so far with other experimental systems. Fission of relativistic uranium ions proved to be a particularly successful process yielding many medium-heavy, neutron-rich nuclei. Insight into the structure of light neutron halos could be improved. The superlarge spatial dimensions of the nuclear halos is discussed. (orig./CB) [de
Understanding Nuclei in the upper sd - shell

OpenAIRE

Sarkar, M. Saha; Bisoi, Abhijit; Ray, Sudatta; Kshetri, Ritesh; Sarkar, S.

2013-01-01

Nuclei in the upper-$sd$ shell usually exhibit characteristics of spherical single particle excitations. In the recent years, employment of sophisticated techniques of gamma spectroscopy has led to observation of high spin states of several nuclei near A$\\simeq$ 40. In a few of them multiparticle, multihole rotational states coexist with states of single particle nature. We have studied a few nuclei in this mass region experimentally, using various campaigns of the Indian National Gamma Array...
Shell-model Monte Carlo studies of nuclei

International Nuclear Information System (INIS)

Dean, D.J.

1997-01-01

The pair content and structure of nuclei near N = Z are described in the frwnework of shell-model Monte Carlo (SMMC) calculations. Results include the enhancement of J=0 T=1 proton-neutron pairing at N=Z nuclei, and the maxked difference of thermal properties between even-even and odd-odd N=Z nuclei. Additionally, a study of the rotational properties of the T=1 (ground state), and T=0 band mixing seen in 74 Rb is presented
Advancing the Theory of Nuclear Reactions with Rare Isotopes. From the Laboratory to the Cosmos

Energy Technology Data Exchange (ETDEWEB)

Nunes, Filomena [Michigan State Univ., East Lansing, MI (United States)

2015-06-01

The mission of the Topical Collaboration on the Theory of Reactions for Unstable iSotopes (TORUS) was to develop new methods to advance nuclear reaction theory for unstable isotopes—particularly the (d,p) reaction in which a deuteron, composed of a proton and a neutron, transfers its neutron to an unstable nucleus. After benchmarking the state-of-the-art theories, the TORUS collaboration found that there were no exact methods to study (d,p) reactions involving heavy targets; the difficulty arising from the long-range nature of the well known, yet subtle, Coulomb force. To overcome this challenge, the TORUS collaboration developed a new theory where the complexity of treating the long-range Coulomb interaction is shifted to the calculation of so-called form-factors. An efficient implementation for the computation of these form factors was a major achievement of the TORUS collaboration. All the new machinery developed are essential ingredients to analyse (d,p) reactions involving heavy nuclei relevant for astrophysics, energy production, and stockpile stewardship.
Particle-rotation coupling in atomic nuclei

International Nuclear Information System (INIS)

Almberger, J.

1980-01-01

Recently an increased interest in the rotational nuclei has been spurred by the new experimental high-spin activities and by the possibilities for lower spins to interpret an impressive amount of experimental data by some comparatively simple model calculations. The author discusses the particle modes of excitation for rotational nuclei in the pairing regime where some puzzles in the theoretical description remain to be resolved. A model comparison is made between the particle-rotor and cranking models which have different definitions of the collective rotation. The cranking model is found to imply a smaller value of the quasiparticle spin alignment than the particle-rotor model. Rotational spectra for both even and odd nuclei are investigated with the use of the many-BCS-quasiparticles plus rotor model. This model gives an accurate description of the ground and S-bands in many even-even rare-earth nuclei. However, the discrepancies for odd-A nuclei between theory and experiments point to the importance of additional physical components. Therefore the rotationally induced quadrupole pair field is considered. This field has an effect on the low spin states in odd-A nuclei, but is not sufficient to account for the experimental data. Another topic considered is the interaction matrix element in crossings for given spin between quasiparticle rotational bands. The matrix elements are found to oscillate as a function of the number of particles, thereby influencing the sharpness of the backbending. Finally the low-spin continuation of the S-band is studied and it is shown that such states can be populated selectively by means of one-particle pickup reactions involving high angular momentum transfer. (Auth.)
Flavanol binding of nuclei from tree species.

Science.gov (United States)

Feucht, W; Treutter, D; Polster, J

2004-01-01

Light microscopy was used to examine the nuclei of five tree species with respect to the presence of flavanols. Flavanols develop a blue colouration in the presence of a special p-dimethylaminocinnamaldehyde (DMACA) reagent that enables those nuclei loaded with flavanols to be recognized. Staining of the nuclei was most pronounced in both Tsuga canadensis and Taxus baccata, variable in Metasequoia glyptostroboides, faint in Coffea arabica and minimal in Prunus avium. HPLC analysis showed that the five species contained substantial amounts of different flavanols such as catechin, epicatechin and proanthocyanidins. Quantitatively, total flavanols were quite different among the species. The nuclei themselves, as studied in Tsuga seed wings, were found to contain mainly catechin, much lower amounts of epicatechin and traces of proanthocyanidins. Blue-coloured nuclei located centrally in small cells were often found to maximally occupy up to 90% of a cell's radius, and the surrounding small rim of cytoplasm was visibly free of flavanols. A survey of 34 gymnosperm and angiosperm species indicated that the first group has much higher nuclear binding capacities for flavanols than the second group.
CO LINE EMISSION FROM COMPACT NUCLEAR STARBURST DISKS AROUND ACTIVE GALACTIC NUCLEI

Energy Technology Data Exchange (ETDEWEB)

Armour, J. N.; Ballantyne, D. R., E-mail: jarmour3@gatech.edu [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332-0430 (United States)

2012-06-20

There is substantial evidence for a connection between star formation in the nuclear region of a galaxy and growth of the central supermassive black hole. Furthermore, starburst activity in the region around an active galactic nucleus (AGN) may provide the obscuration required by the unified model of AGNs. Molecular line emission is one of the best observational avenues to detect and characterize dense, star-forming gas in galactic nuclei over a range of redshift. This paper presents predictions for the carbon monoxide (CO) line features from models of nuclear starburst disks around AGNs. These small-scale ({approx}< 100 pc), dense and hot starbursts have CO luminosities similar to scaled-down ultra-luminous infrared galaxies and quasar host galaxies. Nuclear starburst disks that exhibit a pc-scale starburst and could potentially act as the obscuring torus show more efficient CO excitation and higher brightness temperature ratios than those without such a compact starburst. In addition, the compact starburst models predict strong absorption when J{sub Upper} {approx}> 10, a unique observational signature of these objects. These findings allow for the possibility that CO spectral line energy distributions (SLEDs) could be used to determine if starburst disks are responsible for the obscuration in z {approx}< 1 AGNs. Directly isolating the nuclear CO line emission of such compact regions around AGNs from galactic-scale emission will require high-resolution imaging or selecting AGN host galaxies with weak galactic-scale star formation. Stacking individual CO SLEDs will also be useful in detecting the predicted high-J features.
Neutron rich nuclei around 132Sn

International Nuclear Information System (INIS)

Bhattacharya, Sarmishtha

2016-01-01

The neutron rich nuclei with few particles or holes in 132 Sn have various experimental and theoretical interest to understand the evolution of nuclear structure around the doubly magic shell closure Z=50 and N=82. Some of the exotic neutron rich nuclei in this mass region are situated near waiting points in the r-process path and are of special astrophysical interest. Neutron rich nuclei near 132 Sn have been studied using fission fragment spectroscopy. The lifetime of low lying isomeric states have been precisely measured and the beta decay from the ground and isomeric states have been characterized using gamma-ray spectroscopy
Topological Invariants and Ground-State Wave functions of Topological Insulators on a Torus

Directory of Open Access Journals (Sweden)

Zhong Wang

2014-01-01

Full Text Available We define topological invariants in terms of the ground-state wave functions on a torus. This approach leads to precisely defined formulas for the Hall conductance in four dimensions and the topological magnetoelectric θ term in three dimensions, and their generalizations in higher dimensions. They are valid in the presence of arbitrary many-body interactions and disorder. These topological invariants systematically generalize the two-dimensional Niu-Thouless-Wu formula and will be useful in numerical calculations of disordered topological insulators and strongly correlated topological insulators, especially fractional topological insulators.
Nuclei in a neutron star

International Nuclear Information System (INIS)

Oyamatsu, K.; Yamada, M.

1994-01-01

We report on the recent progress in understanding the matter in the crust of a neutron star. For nuclides in the outer crust, recently measured masses of neutron-rich nuclei enable us to determine more accurately the stable nuclide as a function of the matter density. In the inner crust, the compressible liquid-drop model predicts successive change of the nuclear shape, from sphere to cylinder, slab, cylindrical hole and spherical hole at densities just before the transition to uniform matter. In order to go beyond the liquiddrop model, we performed the Thomas-Fermi calculation paying special attention to the surface diffuseness, and have recently calculated the shell energies of the non-spherical nuclei. We have found from these studies that all these non-spherical nuclei exist stably in the above order even if we include the surface diffuseness and shell energies. (author)
Systematics of light nuclei in a relativistic model

International Nuclear Information System (INIS)

Price, C.E.

1988-01-01

The results of relativistic mean field calculations for non-spherical nuclei are presented and discussed. The need for non-linear scalar meson self-couplings in order to describe the properties of s-d shell nuclei is emphasized along with the importance of self-consistency in calculations of magnetic moments of odd-mass nuclei. 16 refs., 3 figs., 2 tabs
Stability and production of superheavy nuclei

International Nuclear Information System (INIS)

Moeller, P.; Los Alamos National Lab., NM; Nix, J.R.

1997-01-01

Beyond uranium heavy elements rapidly become increasingly unstable with respect to spontaneous fission as the proton number Z increases, because of the disruptive effect of the long-range Coulomb force. However, in the region just beyond Z = 100 magic proton and neutron numbers and the associated shell structure enhances nuclear stability sufficient to allow observation of additional nuclei. Some thirty years ago it was speculated that an island of spherical, relatively stable superheavy nuclei would exist near the next doubly magic proton-neutron combination beyond 208 Pb, that is, at proton number Z 114 and neutron number N = 184. Theory and experiment now show that there also exists a rock of stability in the vicinity of Z = 110 and N = 162 between the actinide region, which previously was the end of the peninsula of known elements, and the predicted island of spherical superheavy nuclei slightly southwest of the magic numbers Z = 114 and N = 184. The authors review here the stability properties of the heavy region of nuclei. Just as the decay properties of nuclei in the heavy region depend strongly on shell structure, this structure also dramatically affects the fusion entrance channel. The six most recently discovered new elements were all formed in cold-fusion reactions. They discuss here the effect of the doubly magic structure of the target in cold-fusion reactions on the fusion barrier and on dissipation
Observation of instability-induced current redistribution in a spherical-torus plasma.

Science.gov (United States)

Menard, J E; Bell, R E; Gates, D A; Kaye, S M; LeBlanc, B P; Levinton, F M; Medley, S S; Sabbagh, S A; Stutman, D; Tritz, K; Yuh, H

2006-09-01

A motional Stark effect diagnostic has been utilized to reconstruct the parallel current density profile in a spherical-torus plasma for the first time. The measured current profile compares favorably with neoclassical theory when no large-scale magnetohydrodynamic instabilities are present in the plasma. However, a current profile anomaly is observed during saturated interchange-type instability activity. This apparent anomaly can be explained by redistribution of neutral beam injection current drive and represents the first observation of interchange-type instabilities causing such redistribution. The associated current profile modifications contribute to sustaining the central safety factor above unity for over five resistive diffusion times, and similar processes may contribute to improved operational scenarios proposed for ITER.
Unified Ideal Stability Limits for Advanced Tokamak and Spherical Torus Plasmas

International Nuclear Information System (INIS)

Menard, J.E.; Bell, M.G.; Bell, R.E.; Gates, D.A.; Kaye, S.M.; LeBlanc, B.P.; Sabbagh, S.A.; Fredrickson, E.D.; Jardin, S.C.; Maingi, R.; Manickam, J.; Mueller, D.; Ono, M.; Paoletti, F.; Peng, Y.-K.M.; Soukhanovskii, V.; Stutman, D.; Synakowski, E.J.

2003-01-01

Ideal magnetohydrodynamic stability limits of shaped tokamak plasmas with high bootstrap fraction are systematically determined as a function of plasma aspect ratio. For plasmas with and without wall stabilization of external kink modes, the computed limits are well described by distinct and nearly invariant values of a normalized beta parameter utilizing the total magnetic field energy density inside the plasma. Stability limit data from the low aspect ratio National Spherical Torus Experiment is compared to these theoretical limits and indicates that ideal nonrotating plasma no-wall beta limits have been exceeded in regimes with sufficiently high cylindrical safety factor. These results could impact the choice of aspect ratio in future fusion power plants

Conceptual design of tritium production fusion reactor based on spherical torus

International Nuclear Information System (INIS)

He Kaihui; Huang Jinhua

2003-01-01

Conceptual design of an advanced tritium production fusion reactor based on spherical torus, which is intermediate application of fusion energy, was presented in this paper. Differing from the traditional tokamak tritium production reactor design, advanced plasma physics performance and compact structural characteristics of ST were used to minimize tritium leakage and maximize tritium breeding ratio with arrangement of tritium production blankets within vacuum vessel as possible in order to produce 1 kg excess tritium except need of self-sufficient plasma core with 40% or more corresponding plant availability. Based on 2D neutronics calculation, preliminary conceptual design of ST-TPR was presented, providing the backgrounds and reference for next detailed conceptual design
Collective models of transition nuclei Pt. 2

International Nuclear Information System (INIS)

Dombradi, Zs.

1982-01-01

The models describing the even-odd and odd-odd transition nuclei (nuclei of moderate ground state deformation) are reviewed. The nuclear core is described by models of even-even nuclei, and the interaction of a single particle and the core is added. Different models of particle-core coupling (phenomenological models, collective models, nuclear field theory, interacting boson-fermion model, vibration nucleon cluster model) and their results are discussed. New developments like dynamical supersymmetry and new research trends are summarized. (D.Gy.)
Particles and nuclei in PANIC

Energy Technology Data Exchange (ETDEWEB)

Anon.

1987-07-15

PANIC is the triennal International Conference on Particles and Nuclei, and judging from the latest PANIC, held in Kyoto from 20-24 April there is no need for panic yet. Faced with two pictures – one of nuclei described in nucleon and meson terms, and another of nucleons containing quarks and gluons – physicists are intrigued to know what new insights from the quark level can tell us about nuclear physics, or vice versa.
Particles and nuclei in PANIC

International Nuclear Information System (INIS)

Anon.

1987-01-01

PANIC is the triennal International Conference on Particles and Nuclei, and judging from the latest PANIC, held in Kyoto from 20-24 April there is no need for panic yet. Faced with two pictures – one of nuclei described in nucleon and meson terms, and another of nucleons containing quarks and gluons – physicists are intrigued to know what new insights from the quark level can tell us about nuclear physics, or vice versa
Understanding nuclei in the upper sd - shell

Energy Technology Data Exchange (ETDEWEB)

Sarkar, M. Saha; Bisoi, Abhijit; Ray, Sudatta [Nuclear Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064 (India); Kshetri, Ritesh [Nuclear Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064, India and Sidho-Kanho-Birsha University, Purulia - 723101 (India); Sarkar, S. [Indian Institute of Engineering Science and Technology, Shibpur, Howrah - 711103 (India)

2014-08-14

Nuclei in the upper-sd shell usually exhibit characteristics of spherical single particle excitations. In the recent years, employment of sophisticated techniques of gamma spectroscopy has led to observation of high spin states of several nuclei near A ≃ 40. In a few of them multiparticle, multihole rotational states coexist with states of single particle nature. We have studied a few nuclei in this mass region experimentally, using various campaigns of the Indian National Gamma Array setup. We have compared and combined our empirical observations with the large-scale shell model results to interpret the structure of these nuclei. Indication of population of states of large deformation has been found in our data. This gives us an opportunity to investigate the interplay of single particle and collective degrees of freedom in this mass region.
Energy and helicity of magnetic torus knots and braids

Science.gov (United States)

Oberti, Chiara; Ricca, Renzo L.

2018-02-01

By considering steady magnetic fields in the shape of torus knots and unknots in ideal magnetohydrodynamics, we compute some fundamental geometric and physical properties to provide estimates for magnetic energy and helicity. By making use of an appropriate parametrization, we show that knots with dominant toroidal coils that are a good model for solar coronal loops have negligible total torsion contribution to magnetic helicity while writhing number provides a good proxy. Hence, by the algebraic definition of writhe based on crossing numbers, we show that the estimated values of writhe based on image analysis provide reliable information for the exact values of helicity. We also show that magnetic energy is linearly related to helicity, and the effect of the confinement of magnetic field can be expressed in terms of geometric information. These results can find useful application in solar and plasma physics, where braided structures are often present.
Quarks in nuclei

International Nuclear Information System (INIS)

Roberts, R.G.

1984-11-01

The paper concerns the behaviour of quarks in nuclei. Confinement size changes and dynamical rescaling; A dependence; low-x region; gluons and confinement size; and nucleons in a nucleus; are all discussed. (U.K.)
Multi-Point Thomson Scattering Diagnostic for the Helicity Injected Torus

Science.gov (United States)

Liptac, J. E.; Smith, R. J.; Hoffman, C. S.; Jarboe, T. R.; Nelson, B. A.; Leblanc, B. P.; Phillips, P.

1999-11-01

The multi-point Thomson scattering system on the Helicity Injected Torus--II can determine electron temperature and density at 11 radial positions at a single time during the plasma discharge. The system includes components on loan from both PPPL and from the University of Texas. The collection optics and Littrow spectrometer from Princeton, and the 1 GW laser and multi-anode microchannel plate detector from Texas have been integrated into a compact structure, creating a mobile and reliable diagnostic. The mobility of the system allows alignment to occur in a room adjacent to the experiment, greatly reducing the disturbance to normal machine operation. The four main parts of the Thomson scattering system, namely, the laser, the beam line, the collection optics, and the mobile structure are presented and discussed.
Microscopic Cluster Theory for Exotic Nuclei

International Nuclear Information System (INIS)

Tomaselli, M; Kuehl, T; Ursescu, D; Fritzsche, S

2006-01-01

For a better understanding of the dynamics of complex exotic nuclei it is of crucial importance to develop a practical microscopic theory easy to be applied to a wide range of masses. In this paper we propose to calculate the structure of neutron-rich nuclei within a dynamic model based on the EoM theory
Mean-field models and exotic nuclei

Energy Technology Data Exchange (ETDEWEB)

Bender, M; Buervenich, T; Maruhn, J A; Greiner, W [Inst. fuer Theoretische Physik, Univ. Frankfurt (Germany); Rutz, K [Inst. fuer Theoretische Physik, Univ. Frankfurt (Germany); [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Reinhard, P G [Inst. fuer Theoretische Physik, Univ. Erlangen (Germany)

1998-06-01

We discuss two widely used nuclear mean-field models, the relativistic mean-field model and the (nonrelativistic) Skyrme-Hartree-Fock model, and their capability to describe exotic nuclei. Test cases are superheavy nuclei and neutron-rich Sn isotopes. New information in this regime helps to fix hitherto loosely determined aspects of the models. (orig.)
Mean-field models and exotic nuclei

International Nuclear Information System (INIS)

Bender, M.; Buervenich, T.; Maruhn, J.A.; Greiner, W.; Rutz, K.; Reinhard, P.G.

1998-01-01

We discuss two widely used nuclear mean-field models, the relativistic mean-field model and the (nonrelativistic) Skyrme-Hartree-Fock model, and their capability to describe exotic nuclei. Test cases are superheavy nuclei and neutron-rich Sn isotopes. New information in this regime helps to fix hitherto loosely determined aspects of the models. (orig.)
Structure functions of nucleons and nuclei

Energy Technology Data Exchange (ETDEWEB)

Bentz, Wolfgang; Ito, Takuya [Department of Physics, Tokai University, Kanagawa (Japan); Cloet, Ian [Department of Physics, University of Washington, Seattle (United States); Thomas, Anthony [Jefferson Lab., Newport News, VA (United States); Yazaki, Koichi [RIKEN, Wako-shi, Saitama (Japan)

2009-07-01

We use an effective chiral quark theory to calculate the quark distributions and structure functions of nucleons and nuclei. The description of the single nucleon is based on the Faddeev framework, and nuclear systems are described in the mean field approximation. Particular amphasis is put on the prediction of the polarized EMC effect in nuclei, and on applications to deep inelastic neutrino-nucleus scattering. Concerning the polarized EMC effect, we discuss the quenching of the quark spin sum in nuclei and its implications for the spin dependent nuclear structure functions, and present results for several nuclei where an experimental observation is feasible. Concerning the case of deep inelastic neutrino-nucleus scattering, we estimate the effect of medium modifications of the quark distribution functions on the measured cross sections, and discuss an interesting resolution of the so called NuTeV anomaly. Finally, we discuss extensions of our model to describe fragmentation functions for semi-inclusive processes. The connection between our effective quark model description and the jet model of Field and Feynman is discussed.
Interactions of 82Pb208 nuclei with energy 158 GeV per nucleon with photoemulsion nuclei

International Nuclear Information System (INIS)

Adamovich, M.I.; Andreeva, N.P.; Bubnov, V.I.; Gajtinov, A.Sh.; Kanygina, Eh.K.; Musaeva, A.K.; Sejtimbetov, A.M.; Skorobagatova, V.I.; Filippova, L.N.; Chasnikov, I.Ya.

1999-01-01

In this report there are experimental data on 82 Pb 208 nuclei (158 GeV) interaction with photoemulsion nuclei. The said data are compared to the similar ones for 79 Au 197 nuclei with less energy (10,7 A GeV). Stack of nuclear emulsion was irradiated with the beam of nuclei 82 Pb 208 at SPS of CERN. Events search was done along the primary nucleus trace. Pb nucleus average path length happened to be λ=(3,8±0,1) cm, this virtually coincides with the one calculated by Brandt and Peters formula (3,9 cm). Secondary particles were identified into s (storm), g (knock-on protons) and b- particles (target nucleus fragments), as well as into nucleus-bullet fragments with different charges (Z=1,2,≥3). This allowed obtaining event distribution by multiplicity of these particles (n s , n g , n b ) and fragments (n z=1,2,≥3 ), calculation of average values by multiplicity (see table), finding correlation of characteristics. >From the table it's clear that when the energy increases s > increases 2,5 times where as g > insignificantly decreases and b > doesn't change
Atmospheric particles acting as ice forming nuclei in different size ranges and cloud condensation nuclei measurements

International Nuclear Information System (INIS)

Santachiara, G.; Di Matteo, L.; Belosi, F.; Prodi, F.

2009-01-01

Measurements of ice nuclei (I N) in different size classes of aerosol P M1, P M2.5, PM10, and total suspended particles (Tsp) were performed at a rural site (S.Pietro Capofiume, in the Po Valley, Italy). Simultaneous measurements of particle number concentrations were also made with a condensation nucleus counter (CN C-TSI), along with particle concentration in different size classes starting from diameter d > 0.3 μm (Optical Spectrometer Grimm, Mod.1.108). No correlation is observed between I N and the particle number concentration measured with the condensation nuclei counter, and there is only a weak correlation with the particle concentration measured using the optical counter, thus confirming the contribution of the accumulation and coarse aerosol fraction. A positive correlation is observed between supersaturation with respect to ice and water values and ice nuclei number concentration, and an exponential dependence of I N on temperature is found. In addition, cloud concentration nuclei (C CN) were measured. The present measurements reveal a diurnal trend, with lower values at about midday and higher ones during the night, a similar trend between C CN and the relative humidity, and opposite to the mixing layer height.
Thomson scattering on ELMO Bumpy Torus

International Nuclear Information System (INIS)

Cobble, J.A.

1985-04-01

Below 10 12 cm -3 density, a Thomson scattering experiment is an exacting task. Aside from the low signal level, the core plasma in this instance is bathed in high-energy x rays, surrounded by a glowing molecular surface plasma, and heated steady state by microwaves. This means that the noise level from radiation is high and the environment is extremely harsh-so harsh that much effort is required to overcome system damage. In spite of this, the ELMO Bumpy Torus (EBT) system has proven itself capable of providing reliable n/sub e/ and T/sub e/ measurements at densities as low as 2 x 10 11 cm -3 . Radial scans across 20 cm of the plasma diameter have been obtained on a routine basis, and the resulting information has been a great help in understanding confinement in the EBT plasma. The bulk electron properties are revealed as flat profiles of n/sub e/ and T/sub e/, with density ranging from 0.5 to 2.0 x 10 12 cm -3 and temperature decreasing from 100 to 20 eV as pressure in the discharge is increased at constant power. Evidence is presented for a suprathermal tail, which amounts to about 10% of the electron distribution at low pressures. The validity of this conclusion is supported by two independent sensitivity calibrations
Proton multiplicity distributions in high-energy hadron-nuclei collisions

International Nuclear Information System (INIS)

Strugalski, Z.

1979-01-01

The fast proton emission process is analyzed in high-energy hadron-nuclei collisions. The formula describing the proton multiplicity distributions is derived. It describes well enough the proton multiplicity distribution of pion-nuclei and proton-nuclei collisions at 200 and 400 GeV
Quantum phase transitions in atomic nuclei

International Nuclear Information System (INIS)

Zamfir, N.V.

2005-01-01

Studies of quantum phase transitions in mesoscopic systems and applications to atomic nuclei are presented. Analysis in terms of the Interacting Boson Model shows that the main features persist even for moderate number of particles. Experimental evidence in rare-earth nuclei is discussed. New order and control parameters for systems with the same number of particles are proposed. (author)
Study of nuclear level densities for exotic nuclei

International Nuclear Information System (INIS)

Nasrabadi, M. N.; Sepiani, M.

2012-01-01

Nuclear level density is one of the properties of nuclei with widespread applications in astrophysics and nuclear medicine. Since there has been little experimental and theoretical research on the study of nuclei which are far from stability line, studying nuclear level density for these nuclei is of crucial importance. Also, as nuclear level density is an important input for nuclear research codes, hence studying the methods for calculation of this parameter is essential. Besides introducing various methods and models for calculating nuclear level density for practical applications, we used exact spectra distribution (SPDM) for determining nuclear level density of two neutron and proton enriched exotic nuclei with the same mass number.
Two-particle spatial correlations in superfluid nuclei

International Nuclear Information System (INIS)

Pillet, N.; Berger, J.-F.; Sandulescu, N.; Schuck, P.

2010-01-01

We discuss the effect of pairing on two-neutron space correlations in deformed nuclei. The spatial correlations are described by the pairing tensor in coordinate space calculated in the HFB approach. Calculations are done using the D1S Gogny force. We show that the pairing tensor has a rather small extension in the relative coordinate, a feature observed earlier in spherical nuclei. It is pointed out that in deformed nuclei the coherence length corresponding to the pairing tensor has a pattern similar to what we have found previously in spherical nuclei; that is, it is maximal in the interior of the nucleus and then it decreases rather rapidly in the surface region, where it reaches a minimal value of about 2 fm. This minimal value of the coherence length in the surface is essentially determined by the finite size properties of single-particle states in the vicinity of the chemical potential and has little to do with enhanced pairing correlations in the nuclear surface. It is shown that in nuclei the coherence length is not a good indicator of the intensity of pairing correlations. This feature is contrasted with the situation in infinite matter.
Electron scattering and reactions from exotic nuclei

International Nuclear Information System (INIS)

Karataglidis, S.

2017-01-01

The SCRIT and FAIR/ELISe experiments are the first to attempt to measure directly electron scattering form factors from nuclei far from stability. This will give direct information for the (one-body) charge densities of those systems, about which there is little information available. The SCRIT experiment will be taking data for medium-mass exotic nuclei, while the electron-ion collider at ELISe, when constructed, will be able to measure form factors for a wide range of exotic nuclei, as available from the radioactive ion beams produced by the FAIR experiment. Other facilities are now being proposed, which will also consider electron scattering from exotic nuclei at higher energies, to study short-range correlations in exclusive reactions. This review will consider all available information concerning the current status (largely theoretical) of electron scattering from exotic nuclei and, where possible, complement such information with equivalent information concerning the neutron densities of those exotic systems, as obtained from intermediate energy proton scattering. The issue of long- and short-range correlations will be discussed, and whether extending such studies to the exotic sector will elicit new information. (orig.)

Electron scattering and reactions from exotic nuclei

Energy Technology Data Exchange (ETDEWEB)

Karataglidis, S. [University of Johannesburg, Department of Physics, Auckland Park (South Africa); University of Melbourne, School of Physics, Victoria (Australia)

2017-04-15

The SCRIT and FAIR/ELISe experiments are the first to attempt to measure directly electron scattering form factors from nuclei far from stability. This will give direct information for the (one-body) charge densities of those systems, about which there is little information available. The SCRIT experiment will be taking data for medium-mass exotic nuclei, while the electron-ion collider at ELISe, when constructed, will be able to measure form factors for a wide range of exotic nuclei, as available from the radioactive ion beams produced by the FAIR experiment. Other facilities are now being proposed, which will also consider electron scattering from exotic nuclei at higher energies, to study short-range correlations in exclusive reactions. This review will consider all available information concerning the current status (largely theoretical) of electron scattering from exotic nuclei and, where possible, complement such information with equivalent information concerning the neutron densities of those exotic systems, as obtained from intermediate energy proton scattering. The issue of long- and short-range correlations will be discussed, and whether extending such studies to the exotic sector will elicit new information. (orig.)
Fundamental Physics with Electroweak Probes of Nuclei

Science.gov (United States)

Pastore, Saori

2018-02-01

The past decade has witnessed tremendous progress in the theoretical and computational tools that produce our understanding of nuclei. A number of microscopic calculations of nuclear electroweak structure and reactions have successfully explained the available experimental data, yielding a complex picture of the way nuclei interact with electroweak probes. This achievement is of great interest from the pure nuclear-physics point of view. But it is of much broader interest too, because the level of accuracy and confidence reached by these calculations opens up the concrete possibility of using nuclei to address open questions in other sub-fields of physics, such as, understanding the fundamental properties of neutrinos, or the particle nature of dark matter. In this talk, I will review recent progress in microscopic calculations of electroweak properties of light nuclei, including electromagnetic moments, form factors and transitions in between lowlying nuclear states along with preliminary studies for single- and double-beta decay rates. I will illustrate the key dynamical features required to explain the available experimental data, and, if time permits, present a novel framework to calculate neutrino-nucleus cross sections for A > 12 nuclei.
Bubble nuclei in relativistic mean field theory

International Nuclear Information System (INIS)

Shukla, A.; Aberg, S.; Patra, S.K.

2011-01-01

Bubble nuclei are characterized by a depletion of their central density, i.e. the formation of the proton or neutron void and subsequently forming proton or neutron bubble nuclei. Possibility of the formation of bubble nuclei has been explored through different nuclear models and in different mass regions. Advancements in experimental nuclear physics has led our experimental access to many new shapes and structures, which were inaccessible hitherto. In the present paper, the possibility of observing nuclear bubble in oxygen isotopes, particularly for 22 O has been studied
Hot nuclei: high temperatures, high angular momenta

International Nuclear Information System (INIS)

Guerreau, D.

1991-01-01

A review is made of the present status concerning the production of hot nuclei above 5 MeV temperature, concentrating mainly on the possible experimental evidences for the attainment of a critical temperature, on the existence of dynamical limitations to the energy deposition and on the experimental signatures for the formation of hot spinning nuclei. The data strongly suggest a nuclear disassembly in collisions involving very heavy ions at moderate incident velocities. Furthermore, hot nuclei seem to be quite stable against rotation on a short time scale. (author) 26 refs.; 12 figs
Structures of exotic nuclei

International Nuclear Information System (INIS)

Hamilton, J.H.

1987-01-01

Discoveries of many different types of nuclear shape coexistence are being found at both low and high excitation energies throughout the periodic table, as documented in recent reviews. Many new types of shape coexistence have been observed at low excitation energies, for examples bands on more than four different overlapping and coexisting shapes are observed in 185 Au, and competing triaxial and prolate shapes in 71 Se and 176 Pt. Discrete states in super-deformed bands with deformations β 2 ∼ 0.4-0.6, coexisting with other shapes, have been seen to high spin up to 60ℎ in 152 Dy, 132 Ce and 135 Nd. Super-deformed nuclei with N and Z both around 38 and around Z = 38, N ≥ 60. These data led to the discovery of new shell gaps and magic numbers of 38 for N and Z and 60 for N but now for deformed shapes. Marked differences in structure are observed at spins of 6 to 20 in nuclei in this region, which differ by only two protons; for example, 68 Ge and 70 Se. The differences are thought to be related to the competing shell gaps in these nuclei
Spectroscopic study of turbulent heating in the high beta tokamak - Torus II

International Nuclear Information System (INIS)

Georgiou, G.E.

1979-01-01

Visible spectroscopy, involving line profile and line intensity measurements, was used to study the turbulent heating of the rectangular cross-section high-beta tokamak Torus II. The spectroscopy was done in the visible wave-length region using a six channel polychrometer having 0.2 A resolution, which is capable of radial scans of the plasma. The plasma, obtained by ionizing helium, is heated by poloidal skin currents, induced by a rapid (tau/sub R/ approx. = 1.7 μsec) change of the toroidal magnetic field either parallel or anti-parallel to the initial toroidal bias magnetic field, which converts a cold toroidal Z-pinch plasma into a hot tokamak plasma
Gravitational waves from the Papaloizou-Pringle instability in black-hole-torus systems.

Science.gov (United States)

Kiuchi, Kenta; Shibata, Masaru; Montero, Pedro J; Font, José A

2011-06-24

Black hole (BH)-torus systems are promising candidates for the central engine of γ-ray bursts (GRBs), and also possible outcomes of the collapse of supermassive stars to supermassive black holes (SMBHs). By three-dimensional general relativistic numerical simulations, we show that an m = 1 nonaxisymmetric instability grows for a wide range of self-gravitating tori orbiting BHs. The resulting nonaxisymmetric structure persists for a time scale much longer than the dynamical one, becoming a strong emitter of large amplitude, quasiperiodic gravitational waves. Our results indicate that both, the central engine of GRBs and newly formed SMBHs, can be strong gravitational wave sources observable by forthcoming ground-based and spacecraft detectors.
Transitional nuclei near shell closures

Energy Technology Data Exchange (ETDEWEB)

Mukherjee, G. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064 (India); Pai, H. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064, India and Present Address: Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstrasse 9, 64289 Darmstadt (Germany)

2014-08-14

High spin states in Bismuth and Thallium nuclei near the Z = 82 shell closure and Cesium nuclei near the N = 82 shell closure in A = 190 and A = 130 regions, respectively, have been experimentally investigated using heavy-ion fusion evaporation reaction and by detecting the gamma rays using the Indian National Gamma Array (INGA). Interesting shape properties in these transitional nuclei have been observed. The results were compared with the neighboring nuclei in these two regions. The total Routhian surface (TRS) calculations have been performed for a better understanding of the observed properties. In mass region A = 190, a change in shape from spherical to deformed has been observd around neutron number N = 112 for the Bi (Z = 83) isotopes with proton number above the magic gap Z = 82, whereas, the shape of Tl (Z = 81) isotopes with proton number below the magic gap Z = 82 remains stable as a function of neutron number. An important transition from aplanar to planar configuration of angular momentum vectors leading to the occurance of nuclar chirality and magnetic rotation, respectively, has been proposed for the unique parity πh{sub 11/2}⊗νh{sub 11/2} configuration in Cs isotopes in the mass region A ∼ 130 around neutron number N = 79. These results are in commensurate with the TRS calculations.
Neutral beam power measurements inside the ASDEX torus

International Nuclear Information System (INIS)

Zengliang, Y.; Staebler, A.; Vollmer, O.

1982-11-01

Neutral beam power measurements inside the ASDEX torus are done with a retractable calorimeter which is only radiation cooled. The calorimeter plate made from Molybdenum is subdivided into nine segments whose increase in energy content due to a shot yields the absorbed beam power. Different models for the backward extrapolation of the measured temperature curves are examined for a series of low energy shots with the result that pure radiation cooling is a valid assumption. Furthermore, a temperature correction to the measured power is derived from these experiments. The evaluation of the shots onto this calorimeter is done by a computer program. The application of this program to a few full power shots shows that a neutral power up to 3.2 MW has been injected into the ASDEX vessel by the two injectors with an overall efficiency of up to 40%. Reionization losses due to the ASDEX stray field are less than 10%; they do not show any dependence upon the pulse length for shots up to 200 ms. (orig.)
Pions scatter by nuclei

International Nuclear Information System (INIS)

Huefner, J.

1975-01-01

Are pions a good tool to study nuclei. If the emphasis of this question rests on ''tool'', the answer must be ''not yet.'' The reason: one does not even understand how a pion interacts with a nucleus. This is part of the many-body problem for strongly interacting particles and its study is a basic problem in physics. One must investigate questions like: Can one understand pion-nucleus interactions from pion-nucleon physics. How does a Δ-resonance look in nuclei. Once one has solved those basic problems, there will be spinoffs in medical, technical and nuclear areas. Then pions can be used as a tool to study nuclear properties
Rotational motion in nuclei

International Nuclear Information System (INIS)

Bohr, A.

1976-01-01

Nuclear structure theories are reviewed concerned with nuclei rotational motion. The development of the deformed nucleus model facilitated a discovery of rotational spectra of nuclei. Comprehensive verification of the rotational scheme and a successful classification of corresponding spectra stimulated investigations of the rotational movement dynamics. Values of nuclear moments of inertia proved to fall between two marginal values corresponding to rotation of a solid and hydrodynamic pattern of an unrotating flow, respectively. The discovery of governing role of the deformation and a degree of a symmetry violence for determining rotational degrees of freedon is pointed out to pave the way for generalization of the rotational spectra
Quasars, Seyfert galaxies and active galactic nuclei

International Nuclear Information System (INIS)

Osterbrock, D.E.

1987-01-01

This chapter is devoted to the spectroscopic methods for analyzing the observed plasma in the nuclei of quasars, Seyfert galazies, and active galactic nuclei. Both the narrow-line region and the broad-line region are discussed. Physical models are presented
Role of neutrons in the fusion of nuclei

International Nuclear Information System (INIS)

Zagrebaev, V. I.; Samarin, V. V.

2007-01-01

The problem of a quantum-mechanical description of a near-barrier fusion of heavy nuclei under conditions of a strong coupling of their relative motion to neutron degrees of freedom is studied. New mutually complementing efficient models employing the multidimensional time-dependent Schroedinger equation and methods for numerically solving the problems in question within these models are proposed. This makes it possible to study the evolution of wave functions for outer neutrons and to calculate nucleon transfer probabilities and occupation numbers for quasimolecular states over the entire energy range, including that of deep-subbarrier energies. It is shown that the valence-neutron wave functions extend over the volumes of both colliding nuclei before their surfaces come into contact and even before these nuclei overcome the Coulomb barrier (collectivization of outer nucleons). This gives rise to a substantial neutron-transfer effect on the fusion of nuclei and, in particular, to a sizable increase in the probability of subbarrier fusion for specific combinations of nuclei
Superheavy nuclei in the relativistic mean-field theory

International Nuclear Information System (INIS)

Lalazissis, G.A.; Ring, P.; Gambhir, Y.K.

1996-01-01

We have carried out a study of superheavy nuclei in the framework of the relativistic mean-field theory. Relativistic Hartree-Bogoliubov (RHB) calculations have been performed for nuclei with large proton and neutron numbers. A finite-range pairing force of Gogny type has been used in the RHB calculations. The ground-state properties of very heavy nuclei with atomic numbers Z=100-114 and neutron numbers N=154-190 have been obtained. The results show that in addition to N=184 the neutron numbers N=160 and N=166 exhibit an extra stability as compared to their neighbors. For the case of protons the atomic number Z=106 is shown to demonstrate a closed-shell behavior in the region of well deformed nuclei about N=160. The proton number Z=114 also indicates a shell closure. Indications for a doubly magic character at Z=106 and N=160 are observed. Implications of shell closures on a possible synthesis of superheavy nuclei are discussed. (orig.)
Electro-magnetic properties of heavy nuclei

International Nuclear Information System (INIS)

Otsuka, Takaharu

1989-01-01

Two topics of electro-magnetic properties of heavy nuclei are discussed. The first topic is the M1 excitation from well-deformed heavy nuclei, and the other is the sudden increase of the isotope shift as a function of N in going away from the closed shell. These problems are considered in terms of the particle-number projected (Nilsson-) BCS calculation. (author)
Quantum-Mechanical Particle Confined to Surfaces of Revolution - Truncated Cone and Elliptic Torus Case Studies

DEFF Research Database (Denmark)

Gravesen, Jens; Willatzen, Morten; Voon, L.C. Lew Yan

2005-01-01

The theory of a quantum-mechanical particle confined to a surface of revolution is described using differential geometry methods including the derivation of a general set of three ordinary differential equations in curved coordinates. The problem is shown to be completely separable with the present...... hard-wall boundary conditions. Two case studies of recent experimental interest. the nanocone and torus-shaped nanoring structures. are analyzed in terms of eigenstates, energies. and symmetry characteristics based on the theory presented....
Tests of the salt-nuclei hypothesis of rain formation

Energy Technology Data Exchange (ETDEWEB)

Woodcock, A H; Blanchard, D C

1955-01-01

Atmospheric chlorides in sea-salt nuclei and the chlorides dissolved in shower rainwaters were recently measured in Hawaii. A comparison of these measurements reveals the remarkable fact that the weight of chloride present in a certain number of nuclei in a cubic meter of clear air tends to be equal to the weight of chloride dissolved in an equal number of raindrops in a cubic meter of rainy air. This result is explained as an indication that the raindrops grow on the salt nuclei in some manner which prevents a marked change in the distribution of these nuclei during the drop-growth process. The data presented add new evidence in further support of the salt-nuclei raindrop hypothesis previously proposed by the first author.
Superheavy nuclei: a relativistic mean field outlook

International Nuclear Information System (INIS)

Afanasjev, A.V.

2006-01-01

The analysis of quasi-particle spectra in the heaviest A∼250 nuclei with spectroscopic data provides an additional constraint for the choice of effective interaction for the description of superheavy nuclei. It strongly suggests that only the parametrizations which predict Z = 120 and N = 172 as shell closures are reliable for superheavy nuclei within the relativistic mean field theory. The influence of the central depression in the density distribution of spherical superheavy nuclei on the shell structure is studied. A large central depression produces large shell gaps at Z = 120 and N = 172. The shell gaps at Z = 126 and N = 184 are favoured by a flat density distribution in the central part of the nucleus. It is shown that approximate particle number projection (PNP) by means of the Lipkin-Nogami (LN) method removes pairing collapse seen at these gaps in the calculations without PNP
Acceleration of compact torus plasma rings in a coaxial rail-gun

International Nuclear Information System (INIS)

Hartman, C.W.; Hammer, J.H.; Eddleman, J.

1986-01-01

They discuss here theoretical studies of magnetic acceleration of Compact Torus plasma rings in a coaxial, rail-gun accelerator. The rings are formed using a magnetized coaxial plasma gun and are accelerated by injection of B/sub Theta/ flux from an accelerator bank. After acceleration, the rings enter a focusing cone where the ring is decelerated and reduced in radius. As the ring radius decreases, the ring magnetic energy increases until it equals the entering kinetic energy and the ring stagnates. Scaling laws and numerical calculations of acceleration using a O-D numerical code are presented. 2-D, MHD simulations are shown which demonstrate ring formation, acceleration, and focusing. Finally, 3-D calculations are discussed which determine the ideal MHD stability of the accelerated ring
Acceleration of compact torus plasma rings in a coaxial rail-gun

International Nuclear Information System (INIS)

Hartman, C.W.; Hammer, J.H.; Eddleman, J.

1985-01-01

We discuss here theoretical studies of magnetic acceleration of Compact Torus plasma rings in a coaxial, rail-gun accelerator. The rings are formed using a magnetized coaxial plasma gun and are accelerated by injection of B/sub theta/ flux from an accelerator bank. After acceleration, the rings enter a focusing cone where the ring is decelerated and reduced in radius. As the ring radius decreases, the ring magnetic energy increases until it equals the entering kinetic energy and the ring stagnates. Scaling laws and numerical calculations of acceleration using a O-D numerical code are presented. 2-D, MHD simulations are shown which demonstrate ring formation, acceleration, and focusing. Finally, 3-D calculations are discussed which determine the ideal MHD stability of the accelerated ring

Design of the fuel processing loop for the Next European Torus

International Nuclear Information System (INIS)

Kalyanam, K.M.; Sood, S.K.; Kveton, O.K.; Busigin, A.; Adamek, F.; Murdoch, D.K.; Leger, D.; Dinner, P.J.; Iseli, M.

1992-01-01

This paper presents a summary of the results of a detailed design study performed for the Fuel Processing Loop of the Next European Torus (NET). The design is based on the concept of adsorption of impurities on molecular sieve at liquid nitrogen temperature, followed by catalytic oxidation of the regenerated impurities to water, and subsequent reduction of the water by electrolysis. The design study has shown that the process can be engineered using, mostly, available components, and can be designed to be safe. Special design features to make the process passively safe are described. The results of a preliminary safety analysis are summarized. Tritium inventories in the various sections of the process loops are shown. A cost estimate for the overall process system is also presented
Applications of high energy neutralized ion beams to a compact torus

International Nuclear Information System (INIS)

Rostoker, N.; Katzenstein, J.

1986-01-01

Pulsed ion beams can be produced with ion diodes and Marx generators. The technology exists to produce high energy beams efficiently. A neutralized ion beam has an equal number of co-moving electrons. The resultant beam is electrically neutral, has no net current and can be transported across a magnetic field if the current density is sufficiently large. Preliminary experimental results have been obtained on injecting a neutralized proton beam into a small tokamak. To illuminate the physical processes involved in injection and trapping an experiment has been designed for TEXT. Possible applications to a compact torus include plasma heating, current maintenance and non-equilibrium reactors that do not require ignition. Each application is discussed and comparisons are made with other methods. (author)
National Spherical Torus Experiment Real Time Plasma Control Data Acquisition Hardware

International Nuclear Information System (INIS)

R.J. Marsala; J. Schneider

2002-01-01

The National Spherical Torus Experiment (NSTX) is currently providing researchers data on low aspect-ratio toroidal plasmas. NSTX's Plasma Control System adjusts the firing angles of thyristor rectifier power supplies, in real time, to control plasma position, shape and density. A Data Acquisition system comprised of off-the-shelf and custom hardware provides the magnetic diagnostics data required in calculating firing angles. This VERSAmodule Eurocard (VME) bus-based system utilizes Front Panel Data Port (FPDP) for high-speed data transfer. Data coming from physically different locations is referenced to several different ground potentials necessitating the need for a custom FPDP multiplexer. This paper discusses the data acquisition system configuration, the in-house designed 4-to-1 FPDP Input Multiplexing Module (FIMM), and future expansion plans
Space potential profiles in ELMO Bumpy Torus (EBT) experiment

International Nuclear Information System (INIS)

Bieniosek, F.M.; Connor, K.A.

1983-01-01

Spatially resolved measurements of the electric space potential in the ELMO Bumpy Torus (EBT) have been made by a heavy ion beam probe. The EBT-I device is characterized by positive potentials in the surface plasma the order of 100 V and by a nearly symmetric potential well in the core plasma of up to 300 V with respect to the surface potential. The EBT-S device has a similar potential structure with well depth and peak potential similar to or greater than that of EBT-I. Peak potential and well depth increase as the edge gas pressure is lowered and as the microwave power is increased. The potential structure is strongly linked to the specific heating geometry. The ambipolar electric field is large enough generally to dominate the core electron neoclassical diffusion. The potential profile is approximately parabolic in the core, which is shown to be a natural consequence of the spatially uniform plasma source function
Imaging of Nuclear Fragmentation in Nuclear Track Emulsion Relativistic Nuclei

International Nuclear Information System (INIS)

Zarubina, I.G. JINR

2011-01-01

The method of nuclear track emulsion provides a uniquely complete observation of multiple fragment systems produced in dissociation of relativistic nuclei. The most valuable events of coherent dissociation of nuclei in narrow jets of light and the lightest nuclei with a net charge as in the initial nucleus, occurring without the production of fragments of the target nuclei and mesons (the so-called w hite s tars), comprise a few percent among the observed interactions. The data on this phenomenon are fragmented, and the interpretation is not offered. The dissociation degree of light O, Ne, Mg and Si, and as well as heavy Au, Pb and U nuclei may reach a complete destruction to light and the lightest nuclei and nucleons, resulting in cluster systems of an unprecedented complexity. Studies with relativistic neutron-deficient nuclei have special advantages due to more complete observations. An extensive collection of macro videos of such interactions in nuclear track emulsion gathered by the Becquerel collaboration is presented
Amygdala nuclei critical for emotional learning exhibit unique gene expression patterns.

Science.gov (United States)

Partin, Alexander C; Hosek, Matthew P; Luong, Jonathan A; Lella, Srihari K; Sharma, Sachein A R; Ploski, Jonathan E

2013-09-01

The amygdala is a heterogeneous, medial temporal lobe structure that has been implicated in the formation, expression and extinction of emotional memories. This structure is composed of numerous nuclei that vary in cytoarchitectonics and neural connections. In particular the lateral nucleus of the amygdala (LA), central nucleus of the amygdala (CeA), and the basal (B) nucleus contribute an essential role to emotional learning. However, to date it is still unclear to what extent these nuclei differ at the molecular level. Therefore we have performed whole genome gene expression analysis on these nuclei to gain a better understanding of the molecular differences and similarities among these nuclei. Specifically the LA, CeA and B nuclei were laser microdissected from the rat brain, and total RNA was isolated from these nuclei and subjected to RNA amplification. Amplified RNA was analyzed by whole genome microarray analysis which revealed that 129 genes are differentially expressed among these nuclei. Notably gene expression patterns differed between the CeA nucleus and the LA and B nuclei. However gene expression differences were not considerably different between the LA and B nuclei. Secondary confirmation of numerous genes was performed by in situ hybridization to validate the microarray findings, which also revealed that for many genes, expression differences among these nuclei were consistent with the embryological origins of these nuclei. Knowing the stable gene expression differences among these nuclei will provide novel avenues of investigation into how these nuclei contribute to emotional arousal and emotional learning, and potentially offer new genetic targets to manipulate emotional learning and memory. Copyright © 2013 Elsevier Inc. All rights reserved.
Growth and Interaction of Colloid Nuclei

Science.gov (United States)

Lam, Michael-Angelo; Khusid, Boris; Meyer, William; Kondic, Lou

2017-11-01

We study evolution of colloid systems under zero-gravity conditions. In particular, we focus on the regime where there is a coexistence between a liquid and a solid state. Under zero gravity, the dominating process in the bulk of the fluid phase and the solid phase is diffusion. At the moving solid/liquid interface, osmotic pressure is balanced by surface tension, as well as balancing fluxes (conservation of mass) with the kinematics of nuclei growth (Wilson-Frenkel law). Due to the highly nonlinear boundary condition at the moving boundary, care has to be taken when performing numerical simulations. In this work, we present a nonlinear model for colloid nuclei growth. Numerical simulations using a finite volume method are compared with asymptotic analysis of the governing equation and experimental results for nuclei growth. Novel component in our numerical simulations is the inclusion of nonlinear (collective) diffusion terms that depend on the chemical potentials of the colloid in the solid and fluid phase. The results include growth and dissolution of a single colloidal nucleus, as well as evolution of multiple interacting nuclei. Supported by NASA Grant No. NNX16AQ79G.
Determining the number of clusters for nuclei segmentation in breast cancer image

Science.gov (United States)

Fatichah, Chastine; Navastara, Dini Adni; Suciati, Nanik; Nuraini, Lubna

2017-02-01

Clustering is commonly technique for image segmentation, however determining an appropriate number of clusters is still challenging. Due to nuclei variation of size and shape in breast cancer image, an automatic determining number of clusters for segmenting the nuclei breast cancer is proposed. The phase of nuclei segmentation in breast cancer image are nuclei detection, touched nuclei detection, and touched nuclei separation. We use the Gram-Schmidt for nuclei cell detection, the geometry feature for touched nuclei detection, and combining of watershed and spatial k-Means clustering for separating the touched nuclei in breast cancer image. The spatial k-Means clustering is employed for separating the touched nuclei, however automatically determine the number of clusters is difficult due to the variation of size and shape of single cell breast cancer. To overcome this problem, first we apply watershed algorithm to separate the touched nuclei and then we calculate the distance among centroids in order to solve the over-segmentation. We merge two centroids that have the distance below threshold. And the new of number centroid as input to segment the nuclei cell using spatial k- Means algorithm. Experiment show that, the proposed scheme can improve the accuracy of nuclei cell counting.
Exotic Nuclei Arena in JHP

International Nuclear Information System (INIS)

Nomura, T.

1991-12-01

The Exotic Nuclei Arena planned in Japanese Hadron Project aims to accelerate various unstable nuclei produced in 1-GeV proton-induced reactions up to 6.5 MeV/u by means of heavy-ion linacs. The present status of research and development for the Earena is briefly reported. The construction of the prototype facility to accelerate unstable beams up to 0.8 MeV/u is planned in 1992-94, in which the existing cyclotron in INS is used as the primary accelerator. (author)
Spinodal decomposition of atomic nuclei

Energy Technology Data Exchange (ETDEWEB)

Chomaz, P. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Colonna, M.; Guarnera, A. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France)]|[LNS, Catania (Italy)

1996-12-31

Multifragmentation of atomic nuclei is discussed. It is shown that this description of the dynamics of first order phase transitions in infinite and finite system is now partially achieved. An important conclusion is that in some specific cases well-defined collective motions were initiating the self-organisation of the unstable matter in fragments. In the case of finite systems the possible signals kept from this early fragmentation stage can inform on the possible occurrence of a liquid-gas phase transition in nuclei. (K.A.). 21 refs.
Spinodal decomposition of atomic nuclei

International Nuclear Information System (INIS)

Chomaz, P.; Colonna, M.; Guarnera, A.

1996-01-01

Multifragmentation of atomic nuclei is discussed. It is shown that this description of the dynamics of first order phase transitions in infinite and finite system is now partially achieved. An important conclusion is that in some specific cases well-defined collective motions were initiating the self-organisation of the unstable matter in fragments. In the case of finite systems the possible signals kept from this early fragmentation stage can inform on the possible occurrence of a liquid-gas phase transition in nuclei. (K.A.)
Structure of neutron-rich nuclei

International Nuclear Information System (INIS)

Nazarewicz, W.; Oak Ridge National Lab., TN; Warsaw Univ.

1997-11-01

One of the frontiers of today's nuclear science is the ''journey to the limits'': of atomic charge and nuclear mass, of neutron-to-proton ratio, and of angular momentum. The new data on exotic nuclei are expected to bring qualitatively new information about the fundamental properties of the nucleonic many-body system, the nature of the nuclear interaction, and nucleonic correlations at various energy-distance scales. In this talk, current developments in nuclear structure of neutron-rich nuclei are discussed from a theoretical perspective
Relativistic mean field theory for unstable nuclei

International Nuclear Information System (INIS)

Toki, Hiroshi

2000-01-01

We discuss the properties of unstable nuclei in the framework of the relativistic mean field (RMF) theory. We take the RMF theory as a phenomenological theory with several parameters, whose form is constrained by the successful microscopic theory (RBHF), and whose values are extracted from the experimental values of unstable nuclei. We find the outcome with the newly obtained parameter sets (TM1 and TMA) is promising in comparison with various experimental data. We calculate systematically the ground state properties of even-even nuclei up to the drip lines; about 2000 nuclei. We find that the neutron magic shells (N=82, 128) at the standard magic numbers stay at the same numbers even far from the stability line and hence provide the feature of the r-process nuclei. However, many proton magic numbers disappear at the neutron numbers far away from the magic numbers due to the deformations. We discuss how to describe giant resonances for the case of the non-linear coupling terms for the sigma and omega mesons in the relativistic RPA. We mention also the importance of the relativistic effect on the spin observables as the Gamow-Teller strength and the longitudinal and transverse spin responses. (author)
The circular loxodromic lines of the torus – Brunelleschi's constructive principle?

Directory of Open Access Journals (Sweden)

Nevena Radojevic

2015-07-01

Full Text Available The umbrella vault of Pazzi Chapel in Santa Croce church in Florence has been the subject of many, 3d survey based researches, but it’s shape has never been described in satisfactory manner. The descriptions given so far, verified through three-dimensional models, despite whether drew near to geometry, did not give any explanation of building process, that as we know, often guides design choises and principles. In the current research, attempts are made to formulate new hypotheses on the logic and form-finding processes that could have determined the choosen shape of the sail. The existing technical literature and treatises on masonry do not give any information about the building processes in the sources, which is a core issue for explaining the peculiar shape of vaults. The analyses are done by correlating detailed surveys and geometric analyses of the vault, comprising the curves, surfaces and the possible masonry texture with the hypothesized form. The form of the inner sail is obtained by a three-dimensional transformation of a toric surface, with respect to the fixed point (dome’s oculus and constant lenght (torus radius, like the Nicomedes concoid in 2d. The vault is made by the inner sail (the concoid surface and the outer sail that is not visible in this moment (the hypothesized toric surface. In this research, and especially in the verification steps, we could recognize as very useful certain measures that, at first, seemed to have no meaning. The inner sail of the umbrella vault of the Pazzi Chapel is built on the basis of a regular dodecagon, with sides of about 4.90 Florentine braccia, while the diameter of the circumscribed circle is about 8.67 braccia, the measures that could seem a bit unusual for Brunelleschian architecture practice. Even the width of the ribs has a not expected measure of 0.38 braccia.When, on the other hand, we go on to describe the genesis of this sail (the inner sail, which is given by a three
Nuclei far off the stability line

International Nuclear Information System (INIS)

Fenyes, T.

1978-01-01

Theoretical and experimental aspects of the formation of some ''exotic'' nuclei far off the stability line were reviewed in addition to the relevant results of research in this field. Results in beta- and gamma-ray spectroscopy, heavy-ion-spectroscopy, achievements in the fields of measuring the atomic mass, the moment, and the radius of the nuclei as well as some astronomical aspects were described. (Z.P.)
Progress Towards High Performance, Steady-state Spherical Torus

International Nuclear Information System (INIS)

Ono, M.; Bell, M.G.; Bell, R.E.; Bigelow, T.; Bitter, M.; Blanchard, W.; Boedo, J.; Bourdelle, C.; Bush, C.; Choe, W.; Chrzanowski, J.; Darrow, D.S.; Diem, S.J.; Doerner, R.; Efthimion, P.C.; Ferron, J.R.; Fonck, R.J.; Fredrickson, E.D.; Garstka, G.D.; Gates, D.A.; Gray, T.; Grisham, L.R.; Heidbrink, W.; Hill, K.W.; Hoffman, D.; Jarboe, T.R.; Johnson, D.W.; Kaita, R.; Kaye, S.M.; Kessel, C.; Kim, J.H.; Kissick, M.W.; Kubota, S.; Kugel, H.W.; LeBlanc, B.P.; Lee, K.; Lee, S.G.; Lewicki, B.T.; Luckhardt, S.; Maingi, R.; Majeski, R.; Manickam, J.; Maqueda, R.; Mau, T.K.; Mazzucato, E.; Medley, S.S.; Menard, J.; Mueller, D.; Nelson, B.A.; Neumeyer, C.; Nishino, N.; Ostrander, C.N.; Pacella, D.; Paoletti, F.; Park, H.K.; Park, W.; Paul, S.F.; Peng, Y.-K. M.; Phillips, C.K.; Pinsker, R.; Probert, P.H.; Ramakrishnan, S.; Raman, R.; Redi, M.; Roquemore, A.L.; Rosenberg, A.; Ryan, P.M.; Sabbagh, S.A.; Schaffer, M.; Schooff, R.J.; Seraydarian, R.; Skinner, C.H.; Sontag, A.C.; Soukhanovskii, V.; Spaleta, J.; Stevenson, T.; Stutman, D.; Swain, D.W.; Synakowski, E.; Takase, Y.; Tang, X.; Taylor, G.; Timberlake, J.; Tritz, K.L.; Unterberg, E.A.; Von Halle, A.; Wilgen, J.; Williams, M.; Wilson, J.R.; Xu, X.; Zweben, S.J.; Akers, R.; Barry, R.E.; Beiersdorfer, P.; Bialek, J.M.; Blagojevic, B.; Bonoli, P.T.; Carter, M.D.; Davis, W.; Deng, B.; Dudek, L.; Egedal, J.; Ellis, R.; Finkenthal, M.; Foley, J.; Fredd, E.; Glasser, A.; Gibney, T.; Gilmore, M.; Goldston, R.J.; Hatcher, R.E.; Hawryluk, R.J.; Houlberg, W.; Harvey, R.; Jardin, S.C.; Hosea, J.C.; Ji, H.; Kalish, M.; Lowrance, J.; Lao, L.L.; Levinton, F.M.; Luhmann, N.C.; Marsala, R.; Mastravito, D.; Menon, M.M.; Mitarai, O.; Nagata, M.; Oliaro, G.; Parsells, R.; Peebles, T.; Peneflor, B.; Piglowski, D.; Porter, G.D.; Ram, A.K.; Rensink, M.; Rewoldt, G.; Roney, P.; Shaing, K.; Shiraiwa, S.; Sichta, P.; Stotler, D.; Stratton, B.C.; Vero, R.; Wampler, W.R.; Wurden, G.A.

2003-01-01

Research on the Spherical Torus (or Spherical Tokamak) is being pursued to explore the scientific benefits of modifying the field line structure from that in more moderate aspect-ratio devices, such as the conventional tokamak. The Spherical Tours (ST) experiments are being conducted in various U.S. research facilities including the MA-class National Spherical Torus Experiment (NSTX) at Princeton, and three medium-size ST research facilities: Pegasus at University of Wisconsin, HIT-II at University of Washington, and CDX-U at Princeton. In the context of the fusion energy development path being formulated in the U.S., an ST-based Component Test Facility (CTF) and, ultimately a Demo device, are being discussed. For these, it is essential to develop high-performance, steady-state operational scenarios. The relevant scientific issues are energy confinement, MHD stability at high beta (B), noninductive sustainment, ohmic-solenoid-free start-up, and power and particle handling. In the confinement area, the NSTX experiments have shown that the confinement can be up to 50% better than the ITER-98-pby2 H-mode scaling, consistent with the requirements for an ST-based CTF and Demo. In NSTX, CTF-relevant average toroidal beta values bT of up to 35% with the near unity central betaT have been obtained. NSTX will be exploring advanced regimes where bT up to 40% can be sustained through active stabilization of resistive wall modes. To date, the most successful technique for noninductive sustainment in NSTX is the high beta-poloidal regime, where discharges with a high noninductive fraction (∼60% bootstrap current + neutral-beam-injected current drive) were sustained over the resistive skin time. Research on radio-frequency-based heating and current drive utilizing HHFW (High Harmonic Fast Wave) and EBW (Electron Bernstein Wave) is also pursued on NSTX, Pegasus, and CDX-U. For noninductive start-up, the Coaxial Helicity Injection (CHI), developed in HIT/HIT-II, has been adopted
Disintegration of comet nuclei

International Nuclear Information System (INIS)

Ksanfomality, Leonid V

2012-01-01

The breaking up of comets into separate pieces, each with its own tail, was seen many times by astronomers of the past. The phenomenon was in sharp contrast to the idea of the eternal and unchangeable celestial firmament and was commonly believed to be an omen of impending disaster, especially for comets with tails stretching across half the sky. It is only now that we have efficient enough space exploration tools to see comet nuclei and even - in the particular case of small comet Hartley-2 in 2010 - to watch their disintegration stage. There are also other suspected candidates for disintegration in the vast family of comet nuclei and other Solar System bodies. (physics of our days)
Disintegration of comet nuclei

Science.gov (United States)

Ksanfomality, Leonid V.

2012-02-01

The breaking up of comets into separate pieces, each with its own tail, was seen many times by astronomers of the past. The phenomenon was in sharp contrast to the idea of the eternal and unchangeable celestial firmament and was commonly believed to be an omen of impending disaster, especially for comets with tails stretching across half the sky. It is only now that we have efficient enough space exploration tools to see comet nuclei and even - in the particular case of small comet Hartley-2 in 2010 - to watch their disintegration stage. There are also other suspected candidates for disintegration in the vast family of comet nuclei and other Solar System bodies.
Effects of a vertical magnetic field on particle confinement in a magnetized plasma torus.

Science.gov (United States)

Müller, S H; Fasoli, A; Labit, B; McGrath, M; Podestà, M; Poli, F M

2004-10-15

The particle confinement in a magnetized plasma torus with superimposed vertical magnetic field is modeled and measured experimentally. The formation of an equilibrium characterized by a parallel plasma current canceling out the grad B and curvature drifts is described using a two-fluid model. Characteristic response frequencies and relaxation rates are calculated. The predictions for the particle confinement time as a function of the vertical magnetic field are verified in a systematic experimental study on the TORPEX device, including the existence of an optimal vertical field and the anticorrelation between confinement time and density.
Deuterium implantation in first wall candidate materials by exposure in the Princeton large torus

Energy Technology Data Exchange (ETDEWEB)

Chang, J.; Tobin, A. (Grumman Aerospace Corp., Bethpage, NY (USA). Research and Development Center); Manos, D. (Princeton Univ., NJ (USA). Plasma Physics Lab.)

Titanium alloys are of interest as a first wall material in fusion reactors because of their excellent thermophysical and thermomechanical properties. A major concern with their application to the first wall is associated with the known affinity of titanium for hydrogen and the related consequences for fuel recycling, tritium inventory, and hydrogen embrittlement. Little information exists on trapping and release of hydrogen isotopes implanted at energies below 500 eV. This work was undertaken to measure hydrogen isotope trapping and release at the first wall of the Princeton Large Torus Tokamak (PLT).

Electronuclear sum rules for the lightest nuclei

International Nuclear Information System (INIS)

Efros, V.D.

1992-01-01

It is shown that the model-independent longitudinal electronuclear sum rules for nuclei with A = 3 and A = 4 have an accuracy on the order of a percent in the traditional single-nucleon approximation with free nucleons for the nuclear charge-density operator. This makes it possible to test this approximation by using these sum rules. The longitudinal sum rules for A = 3 and A = 4 are calculated using the wave functions of these nuclei corresponding to a large set of realistic NN interactions. The values of the model-independent sum rules lie in the range of values calculated by this method. Model-independent expressions are obtained for the transverse sum rules for nuclei with A = 3 and A = 4. These sum rules are calculated using a large set of realistic wave functions of these nuclei. The contribution of the convection current and the changes in the results for different versions of realistic NN forces are given. 29 refs., 4 tabs
Multifractal-based nuclei segmentation in fish images.

Science.gov (United States)

Reljin, Nikola; Slavkovic-Ilic, Marijeta; Tapia, Coya; Cihoric, Nikola; Stankovic, Srdjan

2017-09-01

The method for nuclei segmentation in fluorescence in-situ hybridization (FISH) images, based on the inverse multifractal analysis (IMFA) is proposed. From the blue channel of the FISH image in RGB format, the matrix of Holder exponents, with one-by-one correspondence with the image pixels, is determined first. The following semi-automatic procedure is proposed: initial nuclei segmentation is performed automatically from the matrix of Holder exponents by applying predefined hard thresholding; then the user evaluates the result and is able to refine the segmentation by changing the threshold, if necessary. After successful nuclei segmentation, the HER2 (human epidermal growth factor receptor 2) scoring can be determined in usual way: by counting red and green dots within segmented nuclei, and finding their ratio. The IMFA segmentation method is tested over 100 clinical cases, evaluated by skilled pathologist. Testing results show that the new method has advantages compared to already reported methods.
Contact nuclei formation in aqueous dextrose solutions

Science.gov (United States)

Cerreta, Michael K.; Berglund, Kris A.

1990-06-01

A laser Raman microprobe was used in situ to observe the growth of alpha dextrose monohydrate on alpha anhydrous dextrose crystals. The Raman spectra indicate growth of the monohydrate below 28.1°C, but the presence of only the anhydrous form above 40.5°C. Contact nucleation experiments with parent anhydrous crystals yielded only monohydrate nuclei below 28.1°C, while contacts in solutions between 34.5 and 41.0°C produced both crystalline forms, and contacts in solutions above 43.5°C produced only anhydrous nuclei. The inability of the monohydrate to grow on anhydrous crystals in the same solution that forms the two crystalline phases with a single contact precludes a simple attrition mechanism of nuclei formation. For the same reason, the hypothetical mechanism involving parent crystal stabilization of pre-crystalline clusters, allowing the clusters to grow into nuclei, is also contradicted. A third, mechanism, which may be a combination of the two, is believed to apply.
Spectroscopic Studies of Exotic Nuclei at ISOLDE

CERN Multimedia

2002-01-01

Experiment IS50 is designed to: a) Investigate the full range of the @b strength function of heavy (A~$>$~48)~K nuclei b)~Study the decay of isomeric states in n-deficient bromine nuclei (A~=~72 and 70). The heavy K isotopes appeared to have complex decay schemes, including feeding by the @b-decay of levels having open neutron channels (Beta decay energy Q(@b) exceeds neutron binding energy S^n); in addition, a large fraction of the delayed transitions populate excited levels in the daughter nuclei. The allowed @b-decay selects states in the daughter nucleus with wave functions having a large overlap with the initial state. Hence, the @b strength functions, deduced from these deca reveal simple structures correlated to the particle-hole excitation energies in the Ca nuclei. These results are valuable for the application of the shell-model calculations far from stability. The delayed neutron spectra are measured with a large area curved scintillator in coincidence either with high resolution Ge(Li) detectors, ...
Isospin invariant boson models for fp-shell nuclei

International Nuclear Information System (INIS)

Van Isacker, P.

1994-01-01

Isospin invariant boson models, IBM-3 and IBM-4, applicable in nuclei with neutrons and protons in the same valence shell, are reviewed. Some basic results related to these models are discussed: the mapping onto the shell model, the relation to Wigner's supermultiplet scheme, the boson-number and isospin dependence of parameters, etc. These results are examined for simple single-j shell situations (e.g. f 7/2 ) and their extension to the f p shell is investigated. Other extensions discussed here concern the treatment of odd-mass nuclei and the classification of particle-hole excitations in light nuclei. The possibility of a pseudo-SU(4) supermultiplet scheme in f p -shell nuclei is discussed. (author) 4 figs., 3 tabs., 23 refs
Hirzebruch genera of manifolds with torus action

International Nuclear Information System (INIS)

Panov, T E

2001-01-01

A quasitoric manifold is a smooth 2n-manifold M 2n with an action of the compact torus T n such that the action is locally isomorphic to the standard action of T n on C n and the orbit space is diffeomorphic, as a manifold with corners, to a simple polytope P n . The name refers to the fact that topological and combinatorial properties of quasitoric manifolds are similar to those of non-singular algebraic toric varieties (or toric manifolds). Unlike toric varieties, quasitoric manifolds may fail to be complex. However, they always admit a stably (or weakly almost) complex structure, and their cobordism classes generate the complex cobordism ring. Buchstaber and Ray have recently shown that the stably complex structure on a quasitoric manifold is determined in purely combinatorial terms, namely, by an orientation of the polytope and a function from the set of codimension-one faces of the polytope to primitive vectors of the integer lattice. We calculate the χ y -genus of a quasitoric manifold with a fixed stably complex structure in terms of the corresponding combinatorial data. In particular, this gives explicit formulae for the classical Todd genus and the signature. We also compare our results with well-known facts in the theory of toric varieties
Finite element analysis of an inflatable torus considering air mass structural element

Science.gov (United States)

Gajbhiye, S. C.; Upadhyay, S. H.; Harsha, S. P.

2014-01-01

Inflatable structures, also known as gossamer structures, are at high boom in the current space technology due to their low mass and compact size comparing to the traditional spacecraft designing. Internal pressure becomes the major source of strength and rigidity, essentially stiffen the structure. However, inflatable space based membrane structure are at high risk to the vibration disturbance due to their low structural stiffness and material damping. Hence, the vibration modes of the structure should be known to a high degree of accuracy in order to provide better control authority. In the past, most of the studies conducted on the vibration analysis of gossamer structures used inaccurate or approximate theories in modeling the internal pressure. The toroidal shaped structure is one of the important key element in space application, helps to support the reflector in space application. This paper discusses the finite-element analysis of an inflated torus. The eigen-frequencies are obtained via three-dimensional small-strain elasticity theory, based on extremum energy principle. The two finite-element model (model-1 and model-2) have cases have been generated using a commercial finite-element package. The structure model-1 with shell element and model-2 with the combination of the mass of enclosed fluid (air) added to the shell elements have been taken for the study. The model-1 is computed with present analytical approach to understand the convergence rate and the accuracy. The convergence study is made available for the symmetric modes and anti-symmetric modes about the centroidal-axis plane, meeting the eigen-frequencies of an inflatable torus with the circular cross section. The structural model-2 is introduced with air mass element and analyzed its eigen-frequency with different aspect ratio and mode shape response using in-plane and out-plane loading condition are studied.
Simplest bifurcation diagrams for monotone families of vector fields on a torus

Science.gov (United States)

Baesens, C.; MacKay, R. S.

2018-06-01

In part 1, we prove that the bifurcation diagram for a monotone two-parameter family of vector fields on a torus has to be at least as complicated as the conjectured simplest one proposed in Baesens et al (1991 Physica D 49 387–475). To achieve this, we define ‘simplest’ by sequentially minimising the numbers of equilibria, Bogdanov–Takens points, closed curves of centre and of neutral saddle, intersections of curves of centre and neutral saddle, Reeb components, other invariant annuli, arcs of rotational homoclinic bifurcation of horizontal homotopy type, necklace points, contractible periodic orbits, points of neutral horizontal homoclinic bifurcation and half-plane fan points. We obtain two types of simplest case, including that initially proposed. In part 2, we analyse the bifurcation diagram for an explicit monotone family of vector fields on a torus and prove that it has at most two equilibria, precisely four Bogdanov–Takens points, no closed curves of centre nor closed curves of neutral saddle, at most two Reeb components, precisely four arcs of rotational homoclinic connection of ‘horizontal’ homotopy type, eight horizontal saddle-node loop points, two necklace points, four points of neutral horizontal homoclinic connection, and two half-plane fan points, and there is no simultaneous existence of centre and neutral saddle, nor contractible homoclinic connection to a neutral saddle. Furthermore, we prove that all saddle-nodes, Bogdanov–Takens points, non-neutral and neutral horizontal homoclinic bifurcations are non-degenerate and the Hopf condition is satisfied for all centres. We also find it has four points of degenerate Hopf bifurcation. It thus provides an example of a family satisfying all the assumptions of part 1 except the one of at most one contractible periodic orbit.
Nuclei, hadrons, and elementary particles

International Nuclear Information System (INIS)

Bopp, F.W.

1989-01-01

This book is a short introduction to the physics of the nuclei, hadrons, and elementary particles for students of physics. Important facts and model imaginations on the structure, the decay, and the scattering of nuclei, the 'zoology' of the hadrons and basic facts of hadronic scattering processes, a short introduction to quantum electrodynamics and quantum chromodynamics and the most important processes of lepton and parton physics, as well as the current-current approach of weak interactions and the Glashow-Weinberg-Salam theory are presented. (orig.) With 153 figs., 10 tabs [de
Are there superheavy atomic nuclei

International Nuclear Information System (INIS)

Herrmann, G.

1982-04-01

The author presents a populary introduction to the formation of nuclei with special regards to superheavy nuclei. After a general description of the methods of physics the atomic hypothesis is considered. Thereafter the structure of the nucleus is discussed, and the different isotopes are considered. Then radioactivity is described as an element transmutation. Thereafter the thermonuclear reactions in the sun are considered. Then the synthesis of elements using heavy ion reactions is described. In this connection the transuranium elements and the superheavy elements are considered. (orig./HSI) [de
NEW EQUATIONS OF STATE BASED ON THE LIQUID DROP MODEL OF HEAVY NUCLEI AND QUANTUM APPROACH TO LIGHT NUCLEI FOR CORE-COLLAPSE SUPERNOVA SIMULATIONS

International Nuclear Information System (INIS)

Furusawa, Shun; Yamada, Shoichi; Sumiyoshi, Kohsuke; Suzuki, Hideyuki

2013-01-01

We construct new equations of state for baryons at subnuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to ∼1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell effects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum-theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes
New Equations of State Based on the Liquid Drop Model of Heavy Nuclei and Quantum Approach to Light Nuclei for Core-collapse Supernova Simulations

Science.gov (United States)

Furusawa, Shun; Sumiyoshi, Kohsuke; Yamada, Shoichi; Suzuki, Hideyuki

2013-08-01

We construct new equations of state for baryons at subnuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to ~1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell effects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum-theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes.
NEW EQUATIONS OF STATE BASED ON THE LIQUID DROP MODEL OF HEAVY NUCLEI AND QUANTUM APPROACH TO LIGHT NUCLEI FOR CORE-COLLAPSE SUPERNOVA SIMULATIONS

Energy Technology Data Exchange (ETDEWEB)

Furusawa, Shun; Yamada, Shoichi [Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Sumiyoshi, Kohsuke [Numazu College of Technology, Ooka 3600, Numazu, Shizuoka 410-8501 (Japan); Suzuki, Hideyuki, E-mail: furusawa@heap.phys.waseda.ac.jp [Faculty of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510 (Japan)

2013-08-01

We construct new equations of state for baryons at subnuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to {approx}1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell effects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum-theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes.
Measurements of Prompt and MHD-Induced Fast Ion Loss from National Spherical Torus Experiment Plasmas

Energy Technology Data Exchange (ETDEWEB)

D.S. Darrow; S.S. Medley; A.L. Roquemore; W.W. Heidbrink; A. Alekseyev; F.E. Cecil; J. Egedal; V.Ya. Goloborod' ko; N.N. Gorelenkov; M. Isobe; S. Kaye; M. Miah; F. Paoletti; M.H. Redi; S.N. Reznik; A. Rosenberg; R. White; D. Wyatt; V.A. Yavorskij

2002-10-15

A range of effects may make fast ion confinement in spherical tokamaks worse than in conventional aspect ratio tokamaks. Data from neutron detectors, a neutral particle analyzer, and a fast ion loss diagnostic on the National Spherical Torus Experiment (NSTX) indicate that neutral beam ion confinement is consistent with classical expectations in quiescent plasmas, within the {approx}25% errors of measurement. However, fast ion confinement in NSTX is frequently affected by magnetohydrodynamic (MHD) activity, and the effect of MHD can be quite strong.
Probing the density tail of radioactive nuclei with antiprotons

CERN Document Server

Obertelli, Alexandre; Uesaka, Tomohiro; Corsi, Anna; Pollacco, Emmanuel; Flavigny, Freddy

2017-01-01

We propose an experiment to determine the proton and neutron content of the radial density tail in short-lived nuclei. The objectives are to (i) to evidence new proton and neutron halos, (ii) to understand the development of neutron skins in medium-mass nuclei, (iii) to provide a new observable that characterises the density tail of short-lived nuclei.
The Role of Broken Cooper Pairs in Warm Nuclei

International Nuclear Information System (INIS)

Guttormsen, M.; Chankova, R.; Larsen, A.C.; Rekstad, J.; Siem, S.; Syed, N.U.H.; Agvaanluvsan, U.; Schiller, A.; Voinov, A.

2007-01-01

In order to understand warm nuclei and describe the underlying microscopic structure, entropy is measured for several even-even and odd-mass nuclei. Mid-shell nuclei show significant odd-even entropy differences interpreted as the single-particle entropy introduced by the valence nucleon. A method to extract critical temperatures for the pair breaking process is demonstrated. (author)
Nucleus fingerprinting for the unique identification of Feulgen-stained nuclei

Science.gov (United States)

Friedrich, David; Brozio, Matthias; Bell, André; Biesterfeld, Stefan; Böcking, Alfred; Aach, Til

2012-03-01

DNA Image Cytometry is a method for non-invasive cancer diagnosis which measures the DNA content of Feulgen-stained nuclei. DNA content is measured using a microscope system equipped with a digital camera as a densitometer and estimating the DNA content from the absorption of light when passing through the nuclei. However, a DNA Image Cytometry measurement is only valid if each nucleus is only measured once. To assist the user in preventing multiple measurements of the same nucleus, we have developed a unique digital identifier for the characterization of Feulgen-stained nuclei, the so called Nucleus Fingerprint. Only nuclei with a new fingerprint can be added to the measurement. This fingerprint is based on basic nucleus features, the contour of the nucleus and the spatial relationship to nuclei in the vicinity. Based on this characterization, a classifier for testing two nuclei for identity is presented. In a pairwise comparison of ~40000 pairs of mutually different nuclei, 99.5% were classified as different. In another 450 tests, the fingerprints of the same nucleus recorded a second time were in all cases judged identical. We therefore conclude that our Nucleus Fingerprint approach robustly prevents the repeated measurement of nuclei in DNA Image Cytometry.
Hyperdeformed nuclei and the residual pseudo-SU(3) symmetry

International Nuclear Information System (INIS)

Dudek, J.; Werner, T.

1988-01-01

The author discusses superdeformed and hypothetical hyperdeformed nuclei. Quadrupole deformations characteristic of these types of nuclei are defined. Symmetry features are also discussed. The characteristic cycle dependence of shell structures as functions of the deformation gives rise to chains of the deformed shell closures. Such a chain structure applies to moderately-, super- and hyper-deformed nuclei as well. The resulting total energy calculations give a systematic variation of super- and hyperdeformations with, e.g., increasing N at fixed Z, thus predicting the way nuclei deviate from the simple a:b = 2:1 and a:b = 3:1 symmetries
High energy particle interactions with nuclei

International Nuclear Information System (INIS)

Czyz, W.

1978-01-01

The recent interest in multiparticle production processes on nuclei was triggered by re-discovering their 'enigmatic simplicity' which has been known to cosmic ray physicists for over 20 years: the mean multiplicity and angular distributions of relativistic secondaries produced on nuclei do not differ markedly from what emerges from p-p collisions. The author considers how such reactions may provide a way of obtaining details of hadron structure. (Auth.)
Proton radioactivity from proton-rich nuclei

International Nuclear Information System (INIS)

Guzman, F.; Goncalves, M.; Tavares, O.A.P.; Duarte, S.B.; Garcia, F.; Rodriguez, O.

1999-03-01

Half-lives for proton emission from proton-rich nuclei have been calculated by using the effective liquid drop model of heavy-particle decay of nuclei. It is shown that this model is able to offer results or spontaneous proton-emission half-life-values in excellent agreement with the existing experimental data. Predictions of half-life-values for other possible proton-emission cases are present for null orbital angular momentum. (author)

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