Development of a neutron-polarizing device based on a quadrupole magnet and its application to a focusing SANS instrument

International Nuclear Information System (INIS)

Oku, Takayuki

2009-01-01

We have investigated suitable magnetic field distribution to polarize neutrons based only on the electromagnetic interaction between a neutron magnetic moment and magnetic field, and found out a quadrupole field was the most suitable among simple multipole fields. Then we constructed a quadrupole magnet with a Halbach magnetic circuit as the neutron polarizing device. A cold neutron polarizing experiment of the quadrupole magnet was performed at the beamline C3-1-2-1 (NOP) of JRR-3 at JAEA. By passing through the aperture of the quadrupole magnet, positive and negative polarity neutrons are accelerated in opposite directions and spatially separated. Therefore, we extracted the one-spin component and analyzed its polarization degree. As a result very high neutron polarization degree P=0.9993±0.0025 was obtained. Then the quadrupole magnet was installed into the polarized neutron focusing geometry SANS instrument SANS-J-II of JRR-3. The instrument performance was enhanced by about 10 times compared with the case with the magnetic supermirror as the neutron polarizing device. The details are shown and discussed. (author)

Laced permanent magnet quadrupole drift tube magnets

International Nuclear Information System (INIS)

Feinberg, B.; Behrsing, G.U.; Halbach, K.; Marks, J.S.; Morrison, M.E.; Nelson, D.H.

1988-10-01

A laced permanent magnet quadrupole drift tube magnet has been constructed for a proof-of-principle test. The magnet is a conventional tape-wound quadrupole electromagnet, using iron pole- pieces, with the addition of permanent magnet material (neodymium iron) between the poles to reduce the effects of saturation. The iron is preloaded with magnetic flux generated by the permanent magnet material, resulting in an asymmetrical saturation curve. Since the polarity of the quadrupole magnets in a drift tube linac is not reversed we can take advantage of this asymmetrical saturation to provide greater focusing strength. The magnet configuration has been optimized and the vanadium permendur poles needed in a conventional quadrupole have been replaced with iron poles. The use of permanent magnet material has allowed us to increase the focusing strength of the magnet by about 20% over that of a conventional tape-wound quadrupole. Comparisons will be made between this magnet and the conventional tape-wound quadrupole. 3 refs., 5 figs

Design studies of an electrostatic quadrupole channel for transport of a high-brightness H- beam and comparison with gas focusing

International Nuclear Information System (INIS)

Chang, C.R.; Horowitz, E.; Reiser, M.

1989-01-01

Transport of low-energy, high-brightness H - beams from the ion source to the radio-frequency quadrupole (RFQ) accelerator requires the solution of several physics and engineering problems to avoid particle losses and emittance growth. The authors developed a conceptual design of an electrostatic quadrupole channel for transport of a 120 keV, 120 mA, H - beam into a 425 MHz RFQ with low emittance growth and high transmission efficiency. This design satisfies several constraints imposed by voltage breakdown and beam optics considerations. The system will consist entirely of electrostatic lenses which prevent plasma build-up and eliminate possible emittance growth from plasma fluctuations. Pertinent design features a worst case non-linear analysis for the electrostatic quadrupole channel, and first results of a particle simulation code used to study beam loss and emittance growth are reported. As an alternative to the electrostatic quadrupole concept, gas focusing is being investigated for transporting low-energy H - beams. Recent results from the numerical simulations of such a gas focussing channel are presented

Optimization of Superconducting Focusing Quadrupoles for the HighCurrent Experiment

Energy Technology Data Exchange (ETDEWEB)

Sabbi, GianLuca; Gourlay, Steve; Gung, Chen-yu; Hafalia, Ray; Lietzke, Alan; Martovetski, Nicolai; Mattafirri, Sara; Meinke, Rainer; Minervini, Joseph; Schultz, Joel; Seidl, Peter

2005-09-16

The Heavy Ion Fusion (HIF) program is progressing through a series of physics and technology demonstrations leading to an inertial fusion power plant. The High Current Experiment (HCX) at Lawrence Berkeley National Laboratory is exploring the physics of intense beams with high line-charge density. Superconducting focusing quadrupoles have been developed for the HCX magnetic transport studies. A baseline design was selected following several pre-series models. Optimization of the baseline design led to the development of a first prototype that achieved a conductor-limited gradient of 132 T/m in a 70 mm bore, without training, with measured field errors at the 0.1% level. Based on these results, the magnet geometry and fabrication procedures were adjusted to improve the field quality. These modifications were implemented in a second prototype. In this paper, the optimized design is presented and comparisons between the design harmonics and magnetic measurements performed on the new prototype are discussed.

High gradient superconducting quadrupoles

International Nuclear Information System (INIS)

Lundy, R.A.; Brown, B.C.; Carson, J.A.; Fisk, H.E.; Hanft, R.H.; Mantsch, P.M.; McInturff, A.D.; Remsbottom, R.H.

1987-07-01

Prototype superconducting quadrupoles with a 5 cm aperture and gradient of 16 kG/cm have been built and tested as candidate magnets for the final focus at SLC. The magnets are made from NbTi Tevatron style cable with 10 inner and 14 outer turns per quadrant. Quench performance and multipole data are presented. Design and data for a low current, high gradient quadrupole, similar in cross section but wound with a cable consisting of five insulated conductors are also discussed

Adjustable, short focal length permanent-magnet quadrupole based electron beam final focus system

Directory of Open Access Journals (Sweden)

J. K. Lim

2005-07-01

Full Text Available Advanced high-brightness beam applications such as inverse-Compton scattering (ICS depend on achieving of ultrasmall spot sizes in high current beams. Modern injectors and compressors enable the production of high-brightness beams having needed short bunch lengths and small emittances. Along with these beam properties comes the need to produce tighter foci, using stronger, shorter focal length optics. An approach to creating such strong focusing systems using high-field, small-bore permanent-magnet quadrupoles (PMQs is reported here. A final-focus system employing three PMQs, each composed of 16 neodymium iron boride sectors in a Halbach geometry has been installed in the PLEIADES ICS experiment. The field gradient in these PMQs is 560   T/m, the highest ever reported in a magnetic optics system. As the magnets are of a fixed field strength, the focusing system is tuned by adjusting the position of the three magnets along the beam line axis, in analogy to familiar camera optics. This paper discusses the details of the focusing system, simulation, design, fabrication, and experimental procedure in creating ultrasmall beams at PLEIADES.

Design of an electrostatic magnetic quadrupole accelerator

International Nuclear Information System (INIS)

Mizuno, M.; Ohara, Y.

1993-01-01

A new type of electrostatic acceleration system, electrostatic magnetic quadrupole (ESMQ) acceleration system, is proposed for efficient acceleration of negative ion beams. In this system, permanent magnets are buried in the acceleration electrodes so as to produce a quadrupole magnetic field in the electrode aperture region. Envelope simulation indicates that the quadrupole field can deflect electrons stripped from the negative ions. Beam envelope simulations for deuterium ions and electrons have been carried out using the beam envelope code TRACE. Electrons are largely divergent and most appear likely to hit downstream electrodes. Furthermore, maximum beam divergence of the deuterium ions is reduced to the focusing effect of the quadrupole magnetic field

Catalyst Initiation in the Oscillatory Carbonylation Reaction

Directory of Open Access Journals (Sweden)

Katarina Novakovic

2011-01-01

Full Text Available Palladium(II iodide is used as a catalyst in the phenylacetylene oxidative carbonylation reaction that has demonstrated oscillatory behaviour in both pH and heat of reaction. In an attempt to extract the reaction network responsible for the oscillatory nature of this reaction, the system was divided into smaller parts and they were studied. This paper focuses on understanding the reaction network responsible for the initial reactions of palladium(II iodide within this oscillatory reaction. The species researched include methanol, palladium(II iodide, potassium iodide, and carbon monoxide. Several chemical reactions were considered and applied in a modelling study. The study revealed the significant role played by traces of water contained in the standard HPLC grade methanol used.

Paul trap experiment to simulate intense nonneutral beam propagation through a periodic focusing field configuration

CERN Document Server

Davidson, R C; Majeski, R; Qin, H; Shvets, G

2001-01-01

This paper describes the design concept for a compact Paul trap experimental configuration that fully simulates the collective processes and nonlinear transverse dynamics of an intense charged particle beam that propagates over large distances through a periodic quadrupole magnetic field. To summarize, a long nonneutral plasma column (L>=r sub p) is confined axially by applied DC voltages V[circ]=const. on end cylinders at z=+-L, and transverse confinement is provided by segmented cylindrical electrodes (at radius r sub w) with applied oscillatory voltages +-V sub 0 (t) over 90 deg. segments. Because the transverse focusing force is similar in waveform to that produced by a discrete set of periodic quadrupole magnets in a frame moving with the beam, the Paul trap configuration offers the possibility of simulating intense beam propagation in a compact experimental facility. The nominal operating parameters in the experimental design are: barium ions (A=137); plasma column length 2L=2 m; wall radius r sub w =10...

Study on boiling heat transfer of subcooled flow under oscillatory flow condition

International Nuclear Information System (INIS)

Ohtake, Hiroyasu; Yamazaki, Satoshi; Koizumi, Yasuo

2004-01-01

The Onset of Nucleate Boiling, the point of Net Vapor Generation and Critical Heat Flux on subcooled flow boiling under oscillatory flow, focusing on liquid velocity, amplitude and frequency of oscillatory flow were investigated experimentally and analytically. Experiments were conducted using a copper thin-film and subcooled water in a range of the liquid velocity from 0.27 to 4.07 m/s at 0.10MPa. The liquid subcooling was 20K. Frequency of oscillatory flow was 2 and 4 Hz, respectively; amplitude of oscillatory flow was 25 and 50% in a ratio of main flow rate, respectively. Temperatures at Onset of Nuclear Boiling and Critical Heat Flux obtained in the experiments decreased with the oscillatory flow. The decrease of liquid velocity by oscillatory flow caused the ONB and the CHF to decrease. On the other hand, heat flux at Net Vapor Generation decreased with oscillatory flow; the increase of liquid velocity by oscillatory flow caused the NVG to decrease. (author)

A nonlinear oscillatory problem

International Nuclear Information System (INIS)

Zhou Qingqing.

1991-10-01

We have studied the nonlinear oscillatory problem of orthotropic cylindrical shell, we have analyzed the character of the oscillatory system. The stable condition of the oscillatory system has been given. (author). 6 refs

Stability considerations of permanent magnet quadrupoles for CESR phase-III upgrade

Directory of Open Access Journals (Sweden)

W. Lou

1998-06-01

Full Text Available The Cornell electron storage ring (CESR phase-III upgrade plan includes very strong permanent magnet quadrupoles in front of the cryostat for the superconducting quadrupoles and physically as close as possible to the interaction point. Together with the superconducting quadrupoles, they provide tighter vertical focusing at the interaction point. The quadrupoles are built with neodymium iron boron (NdFeB material and operate inside the 15 kG solenoid field. Requirements on the field quality and stability of these quadrupoles are discussed and test results are presented.

Waferscale Electrostatic Quadrupole Array for Multiple Ion Beam Manipulation

OpenAIRE

Vinayakumar, K. B.; Persaud, A.; Seidl, P. A.; Ji, Q.; Waldron, W. L.; Schenkel, T.; Ardanuc, S.; Lal, A.

2018-01-01

We report on the first through-wafer silicon-based Electrostatic Quadrupole Array (ESQA) to focus high energy ion beams. This device is a key enabler for a wafer based accelerator architecture that lends itself to orders-of-magnitude reduction in cost, volume and weight of charged particle accelerators. ESQs are a key building block in developing compact Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) [1]. In a MEQALAC electrostatic forces are used to focus ions, and elec...

MEQALAC: (multiple electrostatic quadrupole linac): a new approach to low beta rf acceleration

International Nuclear Information System (INIS)

Mobley, R.M.; Brodowski, J.J.; Gammel, G.M.; Keane, J.T.; Maschka, A.W.; Sanders, R.T.

1980-01-01

MEQALAC is an acronym for a multiple-beam electrostatic-quadrupole array linear accelerator. The principle of operation is very simple. It makes use of the fact that electrostatic quadrupoles focus more effectively at low velocities than conventional magnetic quadrupoles. Moreover, the pole-tip field of an electrostatic quadrupole is limited by field emission of electrons, and is not a function of the size of the quadrupole. Conventional magnetic quadrupoles, on the other hand, require increasingly high current densities if one attempts to scale to smaller size

Quadrupole singlet focusing for achromatic parallel-to-parallel devices

International Nuclear Information System (INIS)

Brown, K.L.

1983-01-01

A first order achromatic magnetic deflection system for use in conjunction with a charged particle accelerator is realized from a stepped gap magnet wherein charged particles propagating through the system are subject to at least two adjacent homogeneous magnetic fields in adjacent regions in traversing one-half of a symmetric trajectory through the system. A quadrupole singlet element Q of adjustable focal length disposed substantially at the entrance plane of such a symmetric system makes possible the coincidence of the waists of the beam in both the vertical (transverse) and (radial) bending planes. (author)

All systems go for LHC quadrupoles

CERN Multimedia

2003-01-01

The series fabrication of the Main Quadrupole cold masses for the LHC has begun with the delivery of the first unit on February 12th. The superconducting dipole magnets required to bend the proton beams around the LHC are often in the news. Less famous, perhaps, but equally important are the 360 main quadrupole (MQ) magnets, which will perform the principal focusing around the 27 km ring. CERN and CEA-Saclay began collaborating on the development and prototyping of these magnets in 1989. This resulted in five highly successful quadrupole units - also known as short straight sections - one of which was integrated for testing in String 1, and two others of the final design in String 2. Once the tests had confirmed the validity of the design and realization, the fabrication of the 360 cold masses had to be transferred to industry. After highly competitive tendering, the German firm ACCEL Instruments was entrusted both with the construction of the quadrupole magnets themselves, and with their assembly into the co...

Performance of solenoids versus quadrupoles in focusing and energy selection of laser accelerated protons

Science.gov (United States)

Hofmann, Ingo

2013-04-01

Using laser accelerated protons or ions for various applications—for example in particle therapy or short-pulse radiographic diagnostics—requires an effective method of focusing and energy selection. We derive an analytical scaling for the performance of a solenoid compared with a doublet/triplet as function of the energy, which is confirmed by TRACEWIN simulations. Generally speaking, the two approaches are equivalent in focusing capability, if parameters are such that the solenoid length approximately equals its diameter. The scaling also shows that this is usually not the case above a few MeV; consequently, a solenoid needs to be pulsed or superconducting, whereas the quadrupoles can remain conventional. It is also important that the transmission of the triplet is found only 25% lower than that of the equivalent solenoid. Both systems are equally suitable for energy selection based on their chromatic effect as is shown using an initial distribution following the RPA simulation model by Yan et al. [Phys. Rev. Lett. 103, 135001 (2009PRLTAO0031-900710.1103/PhysRevLett.103.135001].

Performance of solenoids versus quadrupoles in focusing and energy selection of laser accelerated protons

Directory of Open Access Journals (Sweden)

Ingo Hofmann

2013-04-01

Full Text Available Using laser accelerated protons or ions for various applications—for example in particle therapy or short-pulse radiographic diagnostics—requires an effective method of focusing and energy selection. We derive an analytical scaling for the performance of a solenoid compared with a doublet/triplet as function of the energy, which is confirmed by TRACEWIN simulations. Generally speaking, the two approaches are equivalent in focusing capability, if parameters are such that the solenoid length approximately equals its diameter. The scaling also shows that this is usually not the case above a few MeV; consequently, a solenoid needs to be pulsed or superconducting, whereas the quadrupoles can remain conventional. It is also important that the transmission of the triplet is found only 25% lower than that of the equivalent solenoid. Both systems are equally suitable for energy selection based on their chromatic effect as is shown using an initial distribution following the RPA simulation model by Yan et al. [Phys. Rev. Lett. 103, 135001 (2009PRLTAO0031-900710.1103/PhysRevLett.103.135001].

Model of an LHC superconducting quadrupole magnet

CERN Multimedia

Laurent Guiraud

2000-01-01

Model of a superconducting quadrupole magnet for the LHC project. These magnets are used to focus the beam by squeezing it into a smaller cross-section, a similar effect to a lens focusing light. However, each magnet only focuses the beam in one direction so alternating magnet arrangements are required to produce a fully focused beam.

Variable Permanent Magnet Quadrupole

International Nuclear Information System (INIS)

Mihara, T.; Iwashita, Y.; Kyoto U.; Kumada, M.; NIRS, Chiba; Spencer, C.M.; SLAC

2007-01-01

A permanent magnet quadrupole (PMQ) is one of the candidates for the final focus lens in a linear collider. An over 120 T/m strong variable permanent magnet quadrupole is achieved by the introduction of saturated iron and a 'double ring structure'. A fabricated PMQ achieved 24 T integrated gradient with 20 mm bore diameter, 100 mm magnet diameter and 20 cm pole length. The strength of the PMQ is adjustable in 1.4 T steps, due to its 'double ring structure': the PMQ is split into two nested rings; the outer ring is sliced along the beam line into four parts and is rotated to change the strength. This paper describes the variable PMQ from fabrication to recent adjustments

ISABELLE insertion quadrupoles

International Nuclear Information System (INIS)

Kaugerts, J.; Polk, I.; Sampson, W.; Dahl, P.F.

1979-01-01

Beam focussing and control at the beam intersection regions of ISABELLE is accomplished by a number of superconducting insertion quadrupoles. These magnets differ from the standard ISABELLE quadrupoles in various ways. In particular, the requirements of limited space near the intersections and aperture for beam extraction impose constraints on their configuration. To achieve optimum beam focussing and provide tuning flexibility calls for stronger quadrupole trim windings than those in the standard quadrupoles. The magnetic and mechanical design of the insertion quadrupoles and their associated correction and steering windings to accomplish the above tasks is presented

SUPERCONDUCTING QUADRUPOLE ARRAYS FOR MULTIPLE BEAM TRANSPORT

International Nuclear Information System (INIS)

Rainer Meinke Carl Goodzeit Penny Ball Roger Bangerter

2003-01-01

The goal of this research was to develop concepts for affordable, fully functional arrays of superconducting quadrupoles for multi-beam transport and focusing in heavy ion fusion (HIF)accelerators. Previous studies by the Virtual National Laboratory (VNL) collaboration have shown that the multi-beam transport system (consisting of alternating gradient quadrupole magnets, a beam vacuum system, and the beam monitor and control system) will likely be one of the most expensive and critical parts of such an accelerator. This statement is true for near-term fusion research accelerators as well as accelerators for the ultimate goal of power production via inertial fusion. For this reason, research on superconducting quadrupole arrays is both timely and important for the inertial fusion energy (IFE) research program. This research will also benefit near-term heavy ion fusion facilities such as the Integrated Research Experiment (IRE)and/or the Integrated Beam Experiment (IBX). We considered a 2-prong approach that addresses the needs of both the nearer and longer term requirements of the inertial fusion program. First, we studied the flat coil quadrupole design that was developed by LLNL; this magnet is 150 mm long with a 50 mm aperture and thus is suitable for near term experiments that require magnets of a small length to aperture ratio. Secondly, we studied the novel double-helix quadrupole (DHQ) design in a small (3 x 3) array configuration; this design can provide an important step to the longer term solution of loW--cost, easy to manufacture array constructions. Our Phase I studies were performed using the AMPERES magnetostatic analysis software. Consideration of these results led to plans for future magnet RandD construction projects. The first objective of Phase I was to develop the concept of a superconducting focusing array that meets the specific requirements of a heavy ion fusion accelerator. Detailed parameter studies for such quadrupole arrays were performed

SUPERCONDUCTING QUADRUPOLE ARRAYS FOR MULTIPLE BEAM TRANSPORT

Energy Technology Data Exchange (ETDEWEB)

Rainer Meinke

2003-10-01

The goal of this research was to develop concepts for affordable, fully functional arrays of superconducting quadrupoles for multi-beam transport and focusing in heavy ion fusion (HIF)accelerators. Previous studies by the Virtual National Laboratory (VNL) collaboration have shown that the multi-beam transport system (consisting of alternating gradient quadrupole magnets, a beam vacuum system, and the beam monitor and control system) will likely be one of the most expensive and critical parts of such an accelerator. This statement is true for near-term fusion research accelerators as well as accelerators for the ultimate goal of power production via inertial fusion. For this reason, research on superconducting quadrupole arrays is both timely and important for the inertial fusion energy (IFE) research program. This research will also benefit near-term heavy ion fusion facilities such as the Integrated Research Experiment (IRE)and/or the Integrated Beam Experiment (IBX). We considered a 2-prong approach that addresses the needs of both the nearer and longer term requirements of the inertial fusion program. First, we studied the flat coil quadrupole design that was developed by LLNL; this magnet is 150 mm long with a 50 mm aperture and thus is suitable for near term experiments that require magnets of a small length to aperture ratio. Secondly, we studied the novel double-helix quadrupole (DHQ) design in a small (3 x 3) array configuration; this design can provide an important step to the longer term solution of low-cost, easy to manufacture array constructions. Our Phase I studies were performed using the AMPERES magnetostatic analysis software. Consideration of these results led to plans for future magnet R&D construction projects. The first objective of Phase I was to develop the concept of a superconducting focusing array that meets the specific requirements of a heavy ion fusion accelerator. Detailed parameter studies for such quadrupole arrays were performed

Computation of a quadrupole magnet for the APS storage ring

Energy Technology Data Exchange (ETDEWEB)

Turner, L.R.; Kim, S.H.; Thompson, K.M.

1990-01-01

The storage ring of the Advanced Photon Source will include 400 quadrupole magnets for focusing the beam. A prototype quadrupole has been designed, constructed, and measured. This paper describes the two- and three-dimensional (2-D and 3-D) field computations performed for this design. 2 refs., 6 figs., 1 tab.

Permanent quadrupole magnets

International Nuclear Information System (INIS)

Bush, E.D. Jr.

1976-01-01

A family of quadrupole magnets using a soft iron return yoke and circular cross-section permanent magnet poles were fabricated to investigate the feasibility for use in ion or electron beam focusing applications in accelerators and transport lines. Magnetic field measurements yielded promising results. In fixed-field applications, permanent magnets with sufficient gradients would be a low cost substitute for conventional electromagnets, eliminating the need for power supplies, associated wiring, and cooling. (author)

Design of the LINAC4 Transfer Line Quadrupole Electromagnets

CERN Document Server

Vanherpe, L

2013-01-01

Beam focusing in the various segments of the Linac4 Transfer Line is provided by quadrupole electromagnets. In total seventeen pulsed, air-cooled quadrupole electromagnets are required. They are made of laminated electrical steel yokes and coils wound from solid copper wire. All magnets have an aperture radius of 50 mm and are required to provide an integrated field gradient of 1.8 T over a magnetic length of 300 mm. This design report summarizes the main magnetic, electrical and mechanical design parameters of the Linac4 Transfer Line Quadrupole Magnets. The effect of the vacuum chamber on the magnetic field quality and the field delay is studied.

Status report on active stabilisation of a linear collider final focus quadrupole mock-up

International Nuclear Information System (INIS)

Lottin, J.; Brunetti, L.; Formosa, F.; Adloff, C.; Bastian, Y.; Bolzon, B.; Cadoux, F.; Geffroy, N.; Girard, C.; Jeremie, A.; Karyotakis, Y.; Peltier, F.

2006-01-01

The measurements done with the sensors available in our laboratories used for ground motion analysis are presented. The first sensors studied are seismic sensors measuring ground velocity, other sensors are accelerometers available for measuring ground acceleration. The first step has been to characterize the sensors, the second step has been to model and simulate the acceleration in order to identify Eigen frequencies and to display mode shapes. The third step has been to assess the performances of a new algorithm for disturbance rejection. In order to facilitate the analysis, a reduced-size mock-up has been used. The goal was to eliminate or at least to reduce as much as possible the main frequencies of the disturbance. A new mock-up is currently being developed that will have a geometry closer to a final focus quadrupole. Measurements will be done to validate the whole system in view of active stabilization for a future linear collider

Status report on active stabilisation of a linear collider final focus quadrupole mock-up

Energy Technology Data Exchange (ETDEWEB)

Lottin, J.; Brunetti, L.; Formosa, F. [Universite de Savoie, ESIA, 74 - Annecy (France); Adloff, C.; Bastian, Y.; Bolzon, B.; Cadoux, F.; Geffroy, N.; Girard, C.; Jeremie, A.; Karyotakis, Y.; Peltier, F. [LAPP-IN2P3-CNRS, 74 - Annecy-le-Vieux (France)

2006-07-01

The measurements done with the sensors available in our laboratories used for ground motion analysis are presented. The first sensors studied are seismic sensors measuring ground velocity, other sensors are accelerometers available for measuring ground acceleration. The first step has been to characterize the sensors, the second step has been to model and simulate the acceleration in order to identify Eigen frequencies and to display mode shapes. The third step has been to assess the performances of a new algorithm for disturbance rejection. In order to facilitate the analysis, a reduced-size mock-up has been used. The goal was to eliminate or at least to reduce as much as possible the main frequencies of the disturbance. A new mock-up is currently being developed that will have a geometry closer to a final focus quadrupole. Measurements will be done to validate the whole system in view of active stabilization for a future linear collider.

Quadrupole magnets for IR-FEL at RRCAT

International Nuclear Information System (INIS)

Ruwali, Kailash; Singh, Kushraj; Mishra, Anil Kumar; Biswas, Bhaskar

2013-01-01

The IR-FEL project at RRCAT needs quadrupole magnets for focusing 15 to 35 MeV electron beam through a dog-leg type beam line. This bend needs tighter relative tolerances on the central quadrupole triplet . The magnetic design, fabrication and magnetic characterization of five quadrupole magnets were carried out. The poles are detachable and wider than the coils. This significantly improves the good field region of the magnet. The magnet cross-section was optimized using 2D POISON code and entry-exit tapers were optimized using 3D code TOSCA.. The aperture radius of the magnet is 30 mm and the total core length is 180 mm. The integrated gradient of magnet is 0.51 T. The magnetic measurements were carried out using Danfysik make rotating coil bench model 690. Integrated gradient and multipoles present in the magnet aperture were measured at various excitation levels. The details of magnetic development and the magnetic measurements are discussed in this paper. (author)

Eight piece quadrupole magnet, method for aligning quadrupole magent pole tips

Science.gov (United States)

Jaski, Mark S.; Liu, Jie; Donnelly, Aric T.; Downey, Joshua S.; Nudell, Jeremy J.; Jain, Animesh

2018-01-30

The invention provides an alternative to the standard 2-piece or 4-piece quadrupole. For example, an 8-piece and a 10-piece quadrupole are provided whereby the tips of each pole may be adjustable. Also provided is a method for producing a quadrupole using standard machining techniques but which results in a final tolerance accuracy of the resulting construct which is better than that obtained using standard machining techniques.

Development of LHC-IR model quadrupoles in the US

CERN Document Server

Sabbi, G

2007-01-01

Insertion quadrupoles with large aperture and high gradient are required to achieve the luminosity upgrade goal of 1035 cm-2 s-1 at the Large Hadron Collider (LHC). In 2004, the US Department of Energy established the LHC Accelerator Research Program (LARP) to develop a technology base for the upgrade. The focus of the magnet program, which is a collaboration of three US laboratories, BNL, FNAL and LBNL, is on development of high gradient quadrupoles using Nb$_{3}$Sn in order to operate at high field and with sufficient temperature margin. Other program components address issues regarding magnet design, radiation-hard materials, long magnet scale-up, quench protection, fabrication techniques and conductor and cable R&D. This paper reports on the development od model quadrupoles and outlines the long-term goals of the program.

Superconducting magnetic quadrupole

Energy Technology Data Exchange (ETDEWEB)

Kim, J.W.; Shepard, K.W.; Nolen, J.A.

1995-08-01

A design was developed for a 350 T/m, 2.6-cm clear aperture superconducting quadrupole focussing element for use in a very low q/m superconducting linac as discussed below. The quadrupole incorporates holmium pole tips, and a rectangular-section winding using standard commercially-available Nb-Ti wire. The magnet was modeled numerically using both 2D and 3D codes, as a basis for numerical ray tracing using the quadrupole as a linac element. Components for a prototype singlet are being procured during FY 1995.

Nuclear quadrupole-quadrupole interaction in the inelastic scattering of aligned deuterons from deformed nuclei

International Nuclear Information System (INIS)

Clement, H.; Frick, R.; Graw, G.; Schiemenz, P.; Seichert, N.

1983-01-01

The 2 1 + -excitation of deformed nuclei by tensor polarized deuterons provides an alignment of both nuclei and thus a means to study specifically the quadrupole-quadrupole interaction between both nuclei. The tensor analyzing power Asub(xz)(theta) has been measured for the elastic and inelastic scattering on 24 Mg and 28 Si. The coupled channel analysis including a deformed tensor potential reveals a clear signature of the quadrupole-quadrupole part of the nuclear projectile-target interaction. (orig.)

Preliminary proposal of a Nb3Sn quadrupole model for the low β insertions of the LHC

International Nuclear Information System (INIS)

Ambrosio, G.; Ametrano, F.; Bellomo, G.; Broggi, F.; Rossi, L.; Volpini, G.

1995-09-01

In recent years Nb 3 Sn based conductors have shown wide applicability for superconducting magnets in many research areas like high field solenoids for laboratory experiment, for NMR spectroscopy and high field magnets for fusion. Nb 3 Sn technology is progressing fast, increasing both technical reliability and availability. The Nb 3 Sn technology, which has a higher critical field than NbTi, seems attractive for IR (Insertion Region) quadrupoles of large colliders . In this paper it is proposed the construction of a superconducting quadrupole wound with Nb 3 Sn cable for a second generation IR inner triplet low β quadrupoles, for the Large Hadron Collider at CERN. The low β quadrupoles, control the beam focusing at collision points, therefore a gain in term of focus strength and/or coil aperture can increase significantly machine performance. Two are the main steps for the whole project: 1) design and construction of a 1 metre long quadrupole to demonstrate the actual feasibility, which is the subject of this proposal; 2) study for integration of the quadrupole in the machine and final design of 5 m long quadrupoles finalized to the LHC

The first LHC insertion quadrupole

CERN Multimedia

2004-01-01

An important milestone was reached in December 2003 at the CERN Magnet Assembly Facility. The team from the Accelerator Technology - Magnet and Electrical Systems group, AT-MEL, completed the first special superconducting quadrupole for the LHC insertions which house the experiments and major collider systems. The magnet is 8 metres long and contains two matching quadrupole magnets and an orbit corrector, a dipole magnet, used to correct errors in quadrupole alignment. All were tested in liquid helium and reached the ultimate performance criteria required for the LHC. After insertion in the cryostat, the superconducting magnet will be installed as the Q9 quadrupole in sector 7-8, the first sector of the LHC to be put in place in 2004. Members of the quadrupole team, from the AT-MEL group, gathered around the Q9 quadrupole at its inauguration on 12 December 2003 in building 181.

Quadrupole shunt experiments at SPEAR

International Nuclear Information System (INIS)

Corbett, W.J.; Hettel, R.O.; Nuhn, H.-D.

1996-05-01

As part of a program to align and stabilize the SPEAR storage ring, a switchable shunt resistor was installed on each quadrupole to bypass a small percentage of the magnet current. The impact of a quadrupole shunt is to move the electron beam orbit in proportion to the off-axis beam position at the quadrupole, and to shift the betatron tune. Initially, quadrupole shunts in SPEAR were used to position the electron beam in the center of the quadrupoles. This provided readback offsets for nearby beam position monitors, and helped to steer the photon beams with low-amplitude corrector currents. The shunt-induced tune shift measurements were then processed in MAD to derive a lattice model

Oscillatory systems in mitochondria

Energy Technology Data Exchange (ETDEWEB)

Gooch, V D; Packer, L

1974-01-01

Comparison of known mitochondrial oscillatory systems suggest that they all have a common mechanism. Investigation of the requirements of these various systems reveals a common set of basic features that indicate ion-transport processes to be the key components mediating oscillatory behavior. These ion-transport processes include (a) a diffusional transport of a cation and a H/sup +/, (b) a diffusional, non-ionic, coupled transport of a H/sup +/ with a weak acid anion, and (c) an energy-linked H/sup +/ transport. To adequately describe the oscillatory phenomenon, however, it is necessary to consider also the presence of (a) nonlinear concentration profiles of one or more ions within the membrane and its unstirred layers, and (b) feedback loops developed as a result of molecular conformational changes or membrane structural changes affecting ionic flows, each having a major influence on the other.

Preliminary proposal of a Nb{sub 3}Sn quadrupole model for the low {beta} insertions of the LHC

Energy Technology Data Exchange (ETDEWEB)

Ambrosio, G; Ametrano, F; Bellomo, G; Broggi, F; Rossi, L; Volpini, G [Milan Univ. (Italy). Dip. di Fisica; [INFN, Sezione di Milano (Italy). Laboratorio Acceleratori e Superconduttivita` Applicata

1995-09-01

In recent years Nb{sub 3}Sn based conductors have shown wide applicability for superconducting magnets in many research areas like high field solenoids for laboratory experiment, for NMR spectroscopy and high field magnets for fusion. Nb{sub 3}Sn technology is progressing fast, increasing both technical reliability and availability. The Nb{sub 3}Sn technology, which has a higher critical field than NbTi, seems attractive for IR (Insertion Region) quadrupoles of large colliders . In this paper it is proposed the construction of a superconducting quadrupole wound with Nb{sub 3}Sn cable for a second generation IR inner triplet low {beta} quadrupoles, for the Large Hadron Collider at CERN. The low {beta} quadrupoles, control the beam focusing at collision points, therefore a gain in term of focus strength and/or coil aperture can increase significantly machine performance. Two are the main steps for the whole project: (1) design and construction of a 1 metre long quadrupole to demonstrate the actual feasibility, which is the subject of this proposal; (2) study for integration of the quadrupole in the machine and final design of 5 m long quadrupoles finalized to the LHC.

Quadrupole shunt experiments at SPEAR

International Nuclear Information System (INIS)

Corbett, W.J.; Hettel, R.O.; Nuhn, H.

1997-01-01

As part of a program to align and stabilize the SPEAR storage ring, a switchable shunt resistor was installed on each quadrupole to bypass a small percentage of the magnet current. The impact of a quadrupole shunt is to move the electron beam orbit in proportion to the off-axis beam position at the quadrupole and to shift the betatron tune. Initially, quadrupole shunts in SPEAR were used to position the electron beam in the center of the quadrupoles. This provided readback offsets for nearby beam position monitors and helped to steer the photon beams with low-amplitude corrector currents. The shunt-induced tune shift measurements were then processed in MAD to derive a lattice model. copyright 1997 American Institute of Physics

Electric quadrupole strength in nuclei

International Nuclear Information System (INIS)

Kirson, M.W.

1979-01-01

Isoscalar electric quadrupole strength distributions in nuclei are surveyed, and it is concluded that the strength is shared, in most cases, roughly equally between low-lying transitions and the giant quadrupole state. The same is not true of the isovector case. A simple extension of the schematic model gives a remarkably successul description of the data, and emphasizes the vital importance of the coupling between high-lying and low-lying quadrupole modes. The standadrd simple representation of the giant quadrupole resonance as produced by operating on the nuclear ground state with the quadrupole transition operator is not applicable to the isoscalar case. It is suggested that giant resonances fall into broad classes of similar states, with considerable qualitative differences between the distinct classes. (author)

Magnetic field measurements of LHC inner triplet quadrupoles fabricated at Fermilab

International Nuclear Information System (INIS)

Velev, G.V.; Bossert, R.; Carcagno, R.; DiMarco, J.; Feher, S.; Kashikhin, V.V.; Kerby, J.; Lamm, M.; Orris, D.; Schlabach, P.; Strait, J.

2006-01-01

Fermilab, as part of the US-LHC Accelerator Project, is producing superconducting low-beta quadrupole magnets for the Large Hadron Collider (LHC). These 5.5 m long magnets are designed to operate in superfluid helium at 1.9 K with a nominal gradient of 205 T/m in the 70 mm bore. Two quadrupoles separated by a dipole orbit corrector in a single cryogenic assembly comprise the Q2 optical elements of the final focus triplets in the LHC interaction regions. The field quality of the quadrupoles is measured at room temperature during construction of the cold masses as well as during cold testing of the cryogenic assembly. We summarize data from the series measurements of the magnets and discuss various topics of interest

Magnetic field measurements of LHC inner triplet quadrupoles fabricated at Fermilab

Energy Technology Data Exchange (ETDEWEB)

Velev, G.V.; Bossert, R.; Carcagno, R.; DiMarco, J.; Feher, S.; Kashikhin, V.V.; Kerby, J.; Lamm, M.; Orris, D.; Schlabach, P.; Strait, J.; /Fermilab

2006-08-01

Fermilab, as part of the US-LHC Accelerator Project, is producing superconducting low-beta quadrupole magnets for the Large Hadron Collider (LHC). These 5.5 m long magnets are designed to operate in superfluid helium at 1.9 K with a nominal gradient of 205 T/m in the 70 mm bore. Two quadrupoles separated by a dipole orbit corrector in a single cryogenic assembly comprise the Q2 optical elements of the final focus triplets in the LHC interaction regions. The field quality of the quadrupoles is measured at room temperature during construction of the cold masses as well as during cold testing of the cryogenic assembly. We summarize data from the series measurements of the magnets and discuss various topics of interest.

Oscillatory magneto-convection under magnetic field modulation

Directory of Open Access Journals (Sweden)

Palle Kiran

2018-03-01

Full Text Available In this paper we investigate an oscillatory mode of nonlinear magneto-convection under time dependant magnetic field. The time dependant magnetic field consists steady and oscillatory parts. The oscillatory part of the imposed magnetic field is assumed to be of third order. An externally imposed vertical magnetic field in an electrically conducting horizontal fluid layer is considered. The finite amplitude analysis is discussed while perturbing the system. The complex Ginzburg-Landau model is used to derive an amplitude of oscillatory convection for weakly nonlinear mode. Heat transfer is quantified in terms of the Nusselt number, which is governed by the Landau equation. The variation of the modulation excitation of the magnetic field alternates heat transfer in the layer. The modulation excitation of the magnetic field is used either to enhance or diminish the heat transfer in the system. Further, it is found that, oscillatory mode of convection enhances the heat transfer and than stationary convection. The results have possible technological applications in magnetic fluid based systems involving energy transmission. Keywords: Weakly nonlinear theory, Oscillatory convection, Complex Ginzburg Landau model, Magnetic modulation

Oscillatory mechanisms of process binding in memory.

Science.gov (United States)

Klimesch, Wolfgang; Freunberger, Roman; Sauseng, Paul

2010-06-01

A central topic in cognitive neuroscience is the question, which processes underlie large scale communication within and between different neural networks. The basic assumption is that oscillatory phase synchronization plays an important role for process binding--the transient linking of different cognitive processes--which may be considered a special type of large scale communication. We investigate this question for memory processes on the basis of different types of oscillatory synchronization mechanisms. The reviewed findings suggest that theta and alpha phase coupling (and phase reorganization) reflect control processes in two large memory systems, a working memory and a complex knowledge system that comprises semantic long-term memory. It is suggested that alpha phase synchronization may be interpreted in terms of processes that coordinate top-down control (a process guided by expectancy to focus on relevant search areas) and access to memory traces (a process leading to the activation of a memory trace). An analogous interpretation is suggested for theta oscillations and the controlled access to episodic memories. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

SPS Quadrupole Magnets

CERN Multimedia

1974-01-01

A stack of SPS Quadrupole Magnets ready for installation in the tunnel. The SPS uses a total of 216 laminated normal conducting lattice quadrupoles with a length of 3.13 m for the core, 3.3 m overall. The F and D quads. have identical characteristics: inscribed circle radius 44 mm, core height and width 800 mm, maximum gradient 20 Tesla/m.

Source-to-accelerator quadrupole matching section for a compact linear accelerator

Science.gov (United States)

Seidl, P. A.; Persaud, A.; Ghiorso, W.; Ji, Q.; Waldron, W. L.; Lal, A.; Vinayakumar, K. B.; Schenkel, T.

2018-05-01

Recently, we presented a new approach for a compact radio-frequency (RF) accelerator structure and demonstrated the functionality of the individual components: acceleration units and focusing elements. In this paper, we combine these units to form a working accelerator structure: a matching section between the ion source extraction grids and the RF-acceleration unit and electrostatic focusing quadrupoles between successive acceleration units. The matching section consists of six electrostatic quadrupoles (ESQs) fabricated using 3D-printing techniques. The matching section enables us to capture more beam current and to match the beam envelope to conditions for stable transport in an acceleration lattice. We present data from an integrated accelerator consisting of the source, matching section, and an ESQ doublet sandwiched between two RF-acceleration units.

CLIC Quadrupole Module final report

CERN Document Server

Artoos, K; Mainaud-Durand, H

2013-01-01

Future Linear colliders will need particle beam sizes in the nanometre range. The beam also needs to be stable all along the beam line. The CLIC Main Beam Quadrupole (MBQ) module has been defined and studied. It is meant as a test stand for stabilisation and pre-alignment with a MB Quadrupole. The main topic that has been tackled concerns the Quadrupole magnet stabilisation to 1nm at 1Hz. This is needed to obtain the desired CLIC luminosity of 2.1034 cm-2m-1. The deliverable was demonstrated by procuring a MBQ and by stabilising a powered and cooled CLIC MBQ quadrupole. In addition, the stabilisation system has to be compatible with the pre-alignment procedures. Pre-alignment movement resolution has been demonstrated to 1m. The last step is the combined test of stability with a quadrupole on a CLIC Module with the pre-alignment.

Oscillatory magneto-convection under magnetic field modulation

OpenAIRE

Kiran, Palle; Bhadauria, B.S.; Narasimhulu, Y.

2017-01-01

In this paper we investigate an oscillatory mode of nonlinear magneto-convection under time dependant magnetic field. The time dependant magnetic field consists steady and oscillatory parts. The oscillatory part of the imposed magnetic field is assumed to be of third order. An externally imposed vertical magnetic field in an electrically conducting horizontal fluid layer is considered. The finite amplitude analysis is discussed while perturbing the system. The complex Ginzburg-Landau model is...

Radio-frequency quadrupole linear accelerator

International Nuclear Information System (INIS)

Wangler, T.P.; Stokes, R.H.

1980-01-01

The radio-frequency quadrupole (RFQ) is a new linear accelerator concept in which rf electric fields are used to focus, bunch, and accelerate the beam. Because the RFQ can provide strong focusing at low velocities, it can capture a high-current dc ion beam from a low-voltage source and accelerate it to an energy of 1 MeV/nucleon within a distance of a few meters. A recent experimental test at the Los Alamos Scientific Laboratory (LASL) has confirmed the expected performance of this structure and has stimulated interest in a wide variety of applications. The general properties of the RFQ are reviewed and examples of applications of this new accelerator are presented

Emittance measurements by variable quadrupole method

International Nuclear Information System (INIS)

Toprek, D.

2005-01-01

The beam emittance is a measure of both the beam size and beam divergence, we cannot directly measure its value. If the beam size is measured at different locations or under different focusing conditions such that different parts of the phase space ellipse will be probed by the beam size monitor, the beam emittance can be determined. An emittance measurement can be performed by different methods. Here we will consider the varying quadrupole setting method.

MQXFS1 Quadrupole Design Report

Energy Technology Data Exchange (ETDEWEB)

Ambrosio, Giorgio [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); et al.

2016-04-14

This report presents the reference design of MQXFS1, the first 1.5 m prototype of the low-beta quadrupoles (MQXF) for the LHC High Luminosity Upgrade. The MQXF quadrupoles have 150 mm aperture, coil peak field of about 12 T, and use $Nb_{3}Sn$ conductor. The design is based on the LARP HQ quadrupoles, which had 120 mm aperture. MQXFS1 has 1st generation cable cross-section and magnetic design.

General method for final focus system design for circular colliders

Directory of Open Access Journals (Sweden)

Riccardo de Maria

2008-03-01

Full Text Available Colliders use final focus systems to reduce the transverse beam sizes at the interaction point in order to increase collision event rates. The maximum focal strength (gradient of the quadrupoles, and the maximum beam size in them, together limit the beam size reduction that is possible. The goal of a final focus system design is to find the best compromise between quadrupole aperture and quadrupole gradient, for the magnet technology that is used. This paper develops a design method that identifies the intrinsic limitations of a final focus system, validates the results of the method against realistic designs, and reports its application to the upgrade of the Large Hadron Collider final focus.

The team responsible for testing and measuring the LHC insertion quadrupoles

CERN Multimedia

Patrice Loïez

2003-01-01

The LHC main magnet system includes about 600 superconducting quadrupoles for beam focusing. Superconducting Matching Quadrupole Magnets (MQMs) are just one of several varieties of quadrupole; they will be installed in the accelerator´s eight ´insertion zones´, four of which are also experimental areas, where the beams will intersect to produce proton-proton collisions. The first MQM, built by the UK firm Tesla Engineering, has passed its acceptance tests. The team responsible for the tests is pictured here with the 3.5-metre-long magnet. Photo 01: Bottom row, left to right, Michäel Ky, Antoine Dias Goncalves, Gilles Rittaud, Yannick Riva; middle row, left to right, Vladimir Bretin, Noël Dalexandro, Bert Lust, Patrick Viret; top row, left to right, Christian Giloux, Ranko Ostojic, Walter Venturini Delsolaro, Lassaâd Gharsallah.

Centering of quadrupole family

International Nuclear Information System (INIS)

Pinayev, Igor

2007-01-01

A procedure for finding the individual centers for a family of quadrupoles fed with a single power supply is described. The method is generalized for using the correctors adjacent to the quadrupoles. Theoretical background is presented as well as experimental data for the NSLS rings. The method accuracy is also discussed

Ion trajectories quadrupole mass filters

International Nuclear Information System (INIS)

Ursu, D.; Lupsa, N.; Muntean, F.

1994-01-01

The present paper aims at bringing some contributions to the understanding of ion motion in quadrupole mass filters. The theoretical treatment of quadrupole mass filter is intended to be a concise derivation of the important physical relationships using Mathieu functions. A simple iterative method of numerical computation has been used to simulate ion trajectories in an ideal quadrupole field. Finally, some examples of calculation are presented with the aid of computer graphics. (Author) 14 Figs., 1 Tab., 20 Refs

Microfluidic mixing through oscillatory transverse perturbations

Science.gov (United States)

Wu, J. W.; Xia, H. M.; Zhang, Y. Y.; Zhu, P.

2018-05-01

Fluid mixing in miniaturized fluidic devices is a challenging task. In this work, the mixing enhancement through oscillatory transverse perturbations coupling with divergent circular chambers is studied. To simplify the design, an autonomous microfluidic oscillator is used to produce the oscillatory flow. It is then applied to four side-channels that intersect with a central channel of constant flow. The mixing performance is tested at high fluid viscosities of up to 16 cP. Results show that the oscillatory flow can cause strong transverse perturbations which effectively enhance the mixing. The influence of a fluidic capacitor in the central channel is also examined, which at low viscosities can intensify the perturbations and further improve the mixing.

Bidirectional Frontoparietal Oscillatory Systems Support Working Memory.

Science.gov (United States)

Johnson, Elizabeth L; Dewar, Callum D; Solbakk, Anne-Kristin; Endestad, Tor; Meling, Torstein R; Knight, Robert T

2017-06-19

The ability to represent and select information in working memory provides the neurobiological infrastructure for human cognition. For 80 years, dominant views of working memory have focused on the key role of prefrontal cortex (PFC) [1-8]. However, more recent work has implicated posterior cortical regions [9-12], suggesting that PFC engagement during working memory is dependent on the degree of executive demand. We provide evidence from neurological patients with discrete PFC damage that challenges the dominant models attributing working memory to PFC-dependent systems. We show that neural oscillations, which provide a mechanism for PFC to communicate with posterior cortical regions [13], independently subserve communications both to and from PFC-uncovering parallel oscillatory mechanisms for working memory. Fourteen PFC patients and 20 healthy, age-matched controls performed a working memory task where they encoded, maintained, and actively processed information about pairs of common shapes. In controls, the electroencephalogram (EEG) exhibited oscillatory activity in the low-theta range over PFC and directional connectivity from PFC to parieto-occipital regions commensurate with executive processing demands. Concurrent alpha-beta oscillations were observed over parieto-occipital regions, with directional connectivity from parieto-occipital regions to PFC, regardless of processing demands. Accuracy, PFC low-theta activity, and PFC → parieto-occipital connectivity were attenuated in patients, revealing a PFC-independent, alpha-beta system. The PFC patients still demonstrated task proficiency, which indicates that the posterior alpha-beta system provides sufficient resources for working memory. Taken together, our findings reveal neurologically dissociable PFC and parieto-occipital systems and suggest that parallel, bidirectional oscillatory systems form the basis of working memory. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Longitudinal capture in the radio-frequency-quadrupole structure

International Nuclear Information System (INIS)

Inagaki, S.

1980-03-01

The radio-frequency-quadrupole (RFQ) linac structure not only can attain easily transverse focusing in the low-beta region, but also can obtain very high capture efficiency because of its low beta-lambda and low-particle rigidity. An optimization study of the zero space-charge longitudinal capture in an RFQ linac that yields configurations with large capture efficiency is described

Inferring oscillatory modulation in neural spike trains.

Science.gov (United States)

Arai, Kensuke; Kass, Robert E

2017-10-01

Oscillations are observed at various frequency bands in continuous-valued neural recordings like the electroencephalogram (EEG) and local field potential (LFP) in bulk brain matter, and analysis of spike-field coherence reveals that spiking of single neurons often occurs at certain phases of the global oscillation. Oscillatory modulation has been examined in relation to continuous-valued oscillatory signals, and independently from the spike train alone, but behavior or stimulus triggered firing-rate modulation, spiking sparseness, presence of slow modulation not locked to stimuli and irregular oscillations with large variability in oscillatory periods, present challenges to searching for temporal structures present in the spike train. In order to study oscillatory modulation in real data collected under a variety of experimental conditions, we describe a flexible point-process framework we call the Latent Oscillatory Spike Train (LOST) model to decompose the instantaneous firing rate in biologically and behaviorally relevant factors: spiking refractoriness, event-locked firing rate non-stationarity, and trial-to-trial variability accounted for by baseline offset and a stochastic oscillatory modulation. We also extend the LOST model to accommodate changes in the modulatory structure over the duration of the experiment, and thereby discover trial-to-trial variability in the spike-field coherence of a rat primary motor cortical neuron to the LFP theta rhythm. Because LOST incorporates a latent stochastic auto-regressive term, LOST is able to detect oscillations when the firing rate is low, the modulation is weak, and when the modulating oscillation has a broad spectral peak.

Oscillatory integration windows in neurons

Science.gov (United States)

Gupta, Nitin; Singh, Swikriti Saran; Stopfer, Mark

2016-01-01

Oscillatory synchrony among neurons occurs in many species and brain areas, and has been proposed to help neural circuits process information. One hypothesis states that oscillatory input creates cyclic integration windows: specific times in each oscillatory cycle when postsynaptic neurons become especially responsive to inputs. With paired local field potential (LFP) and intracellular recordings and controlled stimulus manipulations we directly test this idea in the locust olfactory system. We find that inputs arriving in Kenyon cells (KCs) sum most effectively in a preferred window of the oscillation cycle. With a computational model, we show that the non-uniform structure of noise in the membrane potential helps mediate this process. Further experiments performed in vivo demonstrate that integration windows can form in the absence of inhibition and at a broad range of oscillation frequencies. Our results reveal how a fundamental coincidence-detection mechanism in a neural circuit functions to decode temporally organized spiking. PMID:27976720

Focusing magnets for HIF based on racetracks

Energy Technology Data Exchange (ETDEWEB)

Martovetsky, N N; Manahan, R R

2000-09-11

Heavy Ion Fusion (HIF) is considered a promising path to a practical fusion reactor. A driver for a HIF reactor will require a large number of quadrupole arrays to focus heavy ion beams. A conceptual design, and trade off studies of the quadrupole array based on racetracks are presented. A comparison with a conventional shell magnet is given and advantages and disadvantages are discussed. A more detailed design of a single quadrupole for the High Current experiment (HCX) is presented and discussed.

Torques on quadrupoles

OpenAIRE

Torres del Castillo, G.F; Méndez Garrido, A

2006-01-01

Making use of the fact that a 2l-pole can be represented by means of l vectors of the same magnitude, the torque on a quadrupole in an inhomogeneous external field is expressed in terms of the vectors that represent the quadrupole and the gradient of the external field. The conditions for rotational equilibrium are also expressed in terms of these vectors. Haciendo uso de que un multipolo de orden 2l puede representarse mediante l vectores de la misma magnitud, la torca sobre un cuadripolo...

Variable high gradient permanent magnet quadrupole (QUAPEVA)

Science.gov (United States)

Marteau, F.; Ghaith, A.; N'Gotta, P.; Benabderrahmane, C.; Valléau, M.; Kitegi, C.; Loulergue, A.; Vétéran, J.; Sebdaoui, M.; André, T.; Le Bec, G.; Chavanne, J.; Vallerand, C.; Oumbarek, D.; Cosson, O.; Forest, F.; Jivkov, P.; Lancelot, J. L.; Couprie, M. E.

2017-12-01

Different applications such as laser plasma acceleration, colliders, and diffraction limited light sources require high gradient quadrupoles, with strength that can reach up to 200 T/m for a typical 10 mm bore diameter. We present here a permanent magnet based quadrupole (so-called QUAPEVA) composed of a Halbach ring and surrounded by four permanent magnet cylinders. Its design including magnetic simulation modeling enabling us to reach 201 T/m with a gradient variability of 45% and mechanical issues are reported. Magnetic measurements of seven systems of different lengths are presented and confirmed the theoretical expectations. The variation of the magnetic center while changing the gradient strength is ±10 μm. A triplet of QUAPEVA magnets is used to efficiently focus a beam with large energy spread and high divergence that is generated by a Laser Plasma Acceleration source for a free electron laser demonstration and has enabled us to perform beam based alignment and control the dispersion of the beam.

Quadrupole moments of hadrons

International Nuclear Information System (INIS)

Krivoruchenko, M.I.

1985-01-01

In chiral bag model an expression is obtained for the quark wave functions with account of color and pion interaction of quarks. The quadrupole moments of nonstrange hadrons are calculated. Quadrupole moment of nucleon isobar is found to be Q(Δ)=-6.3x10 -28 esub(Δ)(cm)sup(2). Fredictions of the chiral bag model are in strong disagreement with the non-relativistic quark model

Engineering Design of Electrostatic Quadrupole for ISOL Beam Lines

International Nuclear Information System (INIS)

Kim, H. S.; Kwon, H. J.; Cho, Y. S.

2014-01-01

In the ISOL system, the RI beam should be transported from the target ion source to post accelerator through various analyzing and charge-breeding systems such as PS (pre-seperator), HRMS (High Resolution Mass Seperator), RF cooler and A/q separator. A reference particle for the beam dynamics calculation is 132 Sn 1+ . After charge breeder system, the charge state is boosted from +1 to +19 with ECR charge breeder and to +33 with EBIS charge breeder. Because the beam energy is as low as 50 keV, the electrostatic optics was adopted rather than the magnetic optics. The electrostatic quadrupole triplets were used for the beam focusing and the electrostatic bender is used for 90-degree bending. In this paper, the design procedure and engineering design of the electrostatic quadrupole are presented

Frequency-dependent oscillatory neural profiles during imitation.

Science.gov (United States)

Sugata, Hisato; Hirata, Masayuki; Tamura, Yuichi; Onishi, Hisao; Goto, Tetsu; Araki, Toshihiko; Yorifuji, Shiro

2017-04-10

Imitation is a complex process that includes higher-order cognitive and motor function. This process requires an observation-execution matching system that transforms an observed action into an identical movement. Although the low-gamma band is thought to reflect higher cognitive processes, no studies have focused on it. Here, we used magnetoencephalography (MEG) to examine the neural oscillatory changes including the low-gamma band during imitation. Twelve healthy, right-handed participants performed a finger task consisting of four conditions (imitation, execution, observation, and rest). During the imitation and execution conditions, significant event-related desynchronizations (ERDs) were observed at the left frontal, central, and parietal MEG sensors in the alpha, beta, and low-gamma bands. Functional connectivity analysis at the sensor level revealed an imitation-related connectivity between a group of frontal sensors and a group of parietal sensors in the low-gamma band. Furthermore, source reconstruction with synthetic aperture magnetometry showed significant ERDs in the low-gamma band in the left sensorimotor area and the middle frontal gyrus (MFG) during the imitation condition when compared with the other three conditions. Our results suggest that the oscillatory neural activities of the low-gamma band at the sensorimotor area and MFG play an important role in the observation-execution matching system related to imitation.

Frequency-dependent oscillatory neural profiles during imitation

Science.gov (United States)

Sugata, Hisato; Hirata, Masayuki; Tamura, Yuichi; Onishi, Hisao; Goto, Tetsu; Araki, Toshihiko; Yorifuji, Shiro

2017-01-01

Imitation is a complex process that includes higher-order cognitive and motor function. This process requires an observation-execution matching system that transforms an observed action into an identical movement. Although the low-gamma band is thought to reflect higher cognitive processes, no studies have focused on it. Here, we used magnetoencephalography (MEG) to examine the neural oscillatory changes including the low-gamma band during imitation. Twelve healthy, right-handed participants performed a finger task consisting of four conditions (imitation, execution, observation, and rest). During the imitation and execution conditions, significant event-related desynchronizations (ERDs) were observed at the left frontal, central, and parietal MEG sensors in the alpha, beta, and low-gamma bands. Functional connectivity analysis at the sensor level revealed an imitation-related connectivity between a group of frontal sensors and a group of parietal sensors in the low-gamma band. Furthermore, source reconstruction with synthetic aperture magnetometry showed significant ERDs in the low-gamma band in the left sensorimotor area and the middle frontal gyrus (MFG) during the imitation condition when compared with the other three conditions. Our results suggest that the oscillatory neural activities of the low-gamma band at the sensorimotor area and MFG play an important role in the observation-execution matching system related to imitation. PMID:28393878

DESIGN OF A THIN QUADRUPOLE TO BE USED IN THE AGS SYNCHROTRON

Energy Technology Data Exchange (ETDEWEB)

TSOUPAS,N.; AHRENS, L.; ALFORQUE, R.; BAI, M.; BROWN, K.; COURANT, E.; ET AL.

2007-06-25

The Alternating Gradient Synchrotron (AGS) employs two partial helical snakes[l] to preserve the polarization of the proton beam during acceleration. In order to compensate for the focusing effect of the partial helical snakes on the beam optics in the AGS during acceleration of the beam, we introduced eight quadrupoles in straight sections of the AGS at the proximity of the partial snakes. At injection energies, the strength of each quad is set at a high value, and is ramped down to zero as the effect of the snakes diminishes by the square of beam's rigidity. Four of the eight compensation quadrupoles had to be placed in very short straight sections -30 cm in length, therefore the quadruples had be thin with an overall length of less than 30 cm. In this paper we will discus: (a) the mechanical and magnetic specifications of the ''thin'' quadrupole. (b) the method to minimize the strength of the dodecapole harmonic, (c) the method to optimize the thickness of the laminations that the magnet iron is made, (d) mechanical tolerances of the magnet, (e) comparison of the measured and calculated magnetic multipoles of the quadrupole.

Radio-frequency quadrupole resonator for linear accelerator

Science.gov (United States)

Moretti, A.

1982-10-19

An RFQ resonator for a linear accelerator having a reduced level of interfering modes and producing a quadrupole mode for focusing, bunching and accelerating beams of heavy charged particles, with the construction being characterized by four elongated resonating rods within a cylinder with the rods being alternately shorted and open electrically to the shell at common ends of the rods to provide an LC parallel resonant circuit when activated by a magnetic field transverse to the longitudinal axis.

Radio frequency quadrupole resonator for linear accelerator

Science.gov (United States)

Moretti, Alfred

1985-01-01

An RFQ resonator for a linear accelerator having a reduced level of interfering modes and producing a quadrupole mode for focusing, bunching and accelerating beams of heavy charged particles, with the construction being characterized by four elongated resonating rods within a cylinder with the rods being alternately shorted and open electrically to the shell at common ends of the rods to provide an LC parallel resonant circuit when activated by a magnetic field transverse to the longitudinal axis.

Quadrupole to BPM offset determination in Indus-2

International Nuclear Information System (INIS)

Jena, Saroj; Ghodke, A.D.; Singh, G.

2009-01-01

A feasibility of finding the quadrupole to BPM offset using beam based alignment (BBA) technique in Indus-2 has been studied. The measurements of the offsets between BPM and quadrupoles could be performed by using quadratic fitting for the minima of the orbit response w. r. t. changes in the quadrupole strengths. These offsets will be integrated to the orbit data during closed orbit correction. There are 72 quadrupoles and 56 BPMs in Indus-2. However the assessment of Quad-BPM offsets is not feasible in some cases due to non-availability of BPM adjacent to quadrupole and also in some cases because of a large phase advance between quadrupole and nearby BPM. Here single corrector method is used to obtain these offsets and assumed the current of each quadrupole can be varied independently. A graphical user interface (GUI) is developed in MATLAB for the use of BBA in Indus-2. (author)

Synchronization in oscillatory networks

CERN Document Server

Osipov, Grigory V; Zhou, Changsong

2007-01-01

The formation of collective behavior in large ensembles or networks of coupled oscillatory elements is one of the oldest and most fundamental aspects of dynamical systems theory. Potential and present applications span a vast spectrum of fields ranging from physics, chemistry, geoscience, through life- and neurosciences to engineering, the economic and the social sciences. This work systematically investigates a large number of oscillatory network configurations that are able to describe many real systems such as electric power grids, lasers or the heart muscle - to name but a few. This book is conceived as an introduction to the field for graduate students in physics and applied mathematics as well as being a compendium for researchers from any field of application interested in quantitative models.

First Test Results of the 150 mm Aperture IR Quadrupole Models for the High Luminosity LHC

CERN Document Server

Ambrosio, G; Wanderer, P; Ferracin, P; Sabbi, G

2017-01-01

The High Luminosity upgrade of the LHC at CERN will use large aperture (150 mm) quadrupole magnets to focus the beams at the interaction points. The high field in the coils requires Nb$_{3}$Sn superconductor technology, which has been brought to maturity by the LHC Accelerator Re-search Program (LARP) over the last 10 years. The key design targets for the new IR quadrupoles were established in 2012, and fabrication of model magnets started in 2014. This paper discusses the results from the first single short coil test and from the first short quadrupole model test. Remaining challenges and plans to address them are also presented and discussed.

First Test Results of the 150 mm Aperture IR Quadrupole Models for the High Luminosity LHC

Energy Technology Data Exchange (ETDEWEB)

Ambrosio, G. [Fermilab; Chlachidze, G. [Fermilab; Wanderer, P. [Brookhaven; Ferracin, P. [CERN; Sabbi, G. [LBNL, Berkeley

2016-10-06

The High Luminosity upgrade of the LHC at CERN will use large aperture (150 mm) quadrupole magnets to focus the beams at the interaction points. The high field in the coils requires Nb3Sn superconductor technology, which has been brought to maturity by the LHC Accelerator Re-search Program (LARP) over the last 10 years. The key design targets for the new IR quadrupoles were established in 2012, and fabrication of model magnets started in 2014. This paper discusses the results from the first single short coil test and from the first short quadrupole model test. Remaining challenges and plans to address them are also presented and discussed.

Three-dimensional quadrupole lenses made with permanent magnets

International Nuclear Information System (INIS)

Ivanov, A.S.

1984-01-01

The performance of accelerator systems with quadrupole magnets can be improved by using permanent magnets in quadrupole lenses. This requires better methods for treating the three-dimensional nature of the magnetic fields and the nonlinear characteristics of the magnets. A numerical method is described for simulating three-dimensional magnetic fields and used to analyze quadrupole lenses and doublets with permanent magnets. The results, which are confirmed experimentally, indicate that both the quadrupole magnetic gradient and the effective field length are changed in permanent-magnet quadrupole lenses when the pole lengths and the gap between the lenses are varied while the other characteristics of the magnets remain unchanged

Series fabrication of the main quadrupole cold masses for the LHC begins

CERN Multimedia

2003-01-01

Three hundred and sixty main quadrupole (MQ) magnets will perform the principal beam focusing around the 27 km LHC ring. CERN and CEA-Saclay began collaborating on the development and prototyping of these magnets in 1989. This resulted in five highly successful quadrupole units - also known as short straight sections - one of which was integrated for testing in String 1, and two others of the final design in String 2. Once the tests had confirmed the validity of the design and realization, the fabrication of the 360 cold masses had to be transferred to industry.The German firm ACCEL Instruments was entrusted both with the construction of the quadrupole magnets themselves, and with their assembly into the cold masses together with various combinations of corrector magnets produced by other European manufacturers. Here we see the first of the cold masses containing the MQ magnet of the machine arcs together with two types of corrector magnet ready for shipping to CERN. Pictured with this first unit, delivered o...

Design principles for robust oscillatory behavior.

Science.gov (United States)

Castillo-Hair, Sebastian M; Villota, Elizabeth R; Coronado, Alberto M

2015-09-01

Oscillatory responses are ubiquitous in regulatory networks of living organisms, a fact that has led to extensive efforts to study and replicate the circuits involved. However, to date, design principles that underlie the robustness of natural oscillators are not completely known. Here we study a three-component enzymatic network model in order to determine the topological requirements for robust oscillation. First, by simulating every possible topological arrangement and varying their parameter values, we demonstrate that robust oscillators can be obtained by augmenting the number of both negative feedback loops and positive autoregulations while maintaining an appropriate balance of positive and negative interactions. We then identify network motifs, whose presence in more complex topologies is a necessary condition for obtaining oscillatory responses. Finally, we pinpoint a series of simple architectural patterns that progressively render more robust oscillators. Together, these findings can help in the design of more reliable synthetic biomolecular networks and may also have implications in the understanding of other oscillatory systems.

Scheme to funnel ion beams with a radio-frequency quadrupole

International Nuclear Information System (INIS)

Stokes, R.H.; Minerbo, G.N.

1985-01-01

We describe a proposed method to funnel ion beams using a new form of the radio-frequency quadrupole (RFQ) structure. This RFQ accepts two bunched ion beams and combines them into a single final beam with interlaced microstructure pulses. It also provides uninterrupted periodic transverse focusing to facilitate the funneling of beams with high current and low emittance

On the choice of the adjusting mouth electrode profile at the input of a linear accelerator with space-uniform quadrupole focusing

International Nuclear Information System (INIS)

Balabin, A.I.; Kapchinskij, I.M.; Lipkin, I.M.

1983-01-01

Beam matching of an electrostatical injector with a linear accelerator is an important problem, since acceptance at the inlet of a linac with space-homogeneous quadrupole focusing (SHQF) does not remain constant but rotates with the frequency of an accelerating field. A possibility of transverse stationary beam matching with the SHQF at the inlet of the linac can be ensured to a considerable extent by means of an initial matching section (matching mouth) at the length of which focusing hardness varies according to a certain law. In this case the purpose of creating beam matching conditions practically independent of the phases of particles at the inlet into the mouth is attained. Transverse beam matching for different laws of focusing hardness variation along the non-modulated mouth is investigated. It is shown that for earlier suggested laws of hardness variation the matching conditions at the mouth inlet are critically dependent on the input phases of particles at high phase densities of the beam current j. Laws of hardness variation ensuring actual matching condition independence of the phases of particles up to j=2 A/cmxmrad (for protons) are suggested. A case of beam matching by means of the modulated mouth is also considered. Recommendations on mouth modulation laws are given

Electrostatic quadrupoles for heavy-ion fusion

International Nuclear Information System (INIS)

Seidl, P.; Faltens, A.

1993-05-01

Voltage-holding data for three quadrupole electrode sizes and inter-electrode spacings are reported. The dependence of the breakdown voltage on system size and its influence on the optimum quadrupole size for beam transport in a multiple beam array are discussed

A comparison of ray-tracing software for the design of quadrupole microbeam systems

International Nuclear Information System (INIS)

Incerti, S.; Smith, R.W.; Merchant, M.; Grime, G.W.; Meot, F.; Serani, L.; Moretto, Ph.; Touzeau, C.; Barberet, Ph.; Habchi, C.; Nguyen, D.T.

2005-01-01

For many years the only ray-tracing software available with sufficient precision for the design of quadrupole microbeam focusing systems has been OXRAY and its successor TRAX, developed at Oxford in the 1980s. With the current interest in pushing the beam diameter into the nanometre region, this software has become dated and more importantly the precision at small displacements may not be sufficient and new simulation tools are required. Two candidates for this are Zgoubi, developed at CEA as a general beam line design tool and the CERN simulation program Geant in its latest version Geant4. In order to use Geant4 new quadrupole field modules have been developed and implemented. In this paper the capabilities of the three codes TRAX, Zgoubi and Geant4 are reviewed. Comparisons of ray-tracing calculations in a high demagnification quadrupole probe-forming system for the sub-micron region are presented

Characterization of vertical mixing in oscillatory vegetated flows

Science.gov (United States)

Abdolahpour, M.; Ghisalberti, M.; Lavery, P.; McMahon, K.

2016-02-01

Seagrass meadows are primary producers that provide important ecosystem services, such as improved water quality, sediment stabilisation and trapping and recycling of nutrients. Most of these ecological services are strongly influenced by the vertical exchange of water across the canopy-water interface. That is, vertical mixing is the main hydrodynamic process governing the large-scale ecological and environmental impact of seagrass meadows. The majority of studies into mixing in vegetated flows have focused on steady flow environments whereas many coastal canopies are subjected to oscillatory flows driven by surface waves. It is known that the rate of mass transfer will vary greatly between unidirectional and oscillatory flows, necessitating a specific investigation of mixing in oscillatory canopy flows. In this study, we conducted an extensive laboratory investigation to characterise the rate of vertical mixing through a vertical turbulent diffusivity (Dt,z). This has been done through gauging the evolution of vertical profiles of concentration (C) of a dye sheet injected into a wave-canopy flow. Instantaneous measurement of the variance of the vertical concentration distribution ( allowed the estimation of a vertical turbulent diffusivity (). Two types of model canopies, rigid and flexible, with identical heights and frontal areas, were subjected to a wide and realistic range of wave height and period. The results showed two important mechanisms that dominate vertical mixing under different conditions: a shear layer that forms at the top of the canopy and wake turbulence generated by the stems. By allowing a coupled contribution of wake and shear layer mixing, we present a relationship that can be used to predict the rate of vertical mixing in coastal canopies. The results further showed that the rate of vertical mixing within flexible vegetation was always lower than the corresponding rigid canopy, confirming the impact of plant flexibility on canopy

A strong focussing cylindrical electrostatic quadrupole

International Nuclear Information System (INIS)

Sheng Yaochang

1986-01-01

The construction and performance of small cylindrical electrostatic quadrupole, which is installed in JM-400 pulse electrostatic accelerator, are described. This electrostatic quadrupole is not only used in neutron generator, but also suitable for ion injector as well as for low energy electron accelerator

Transport properties of a discrete helical electrostatic quadrupole

International Nuclear Information System (INIS)

Meitzler, C.R.; Antes, K.; Datte, P.; Huson, F.R.; Xiu, L.

1991-01-01

The helical electrostatic quadrupole (HESQ) lens has been proposed as a low energy beam transport system which permits intense H - beams to be focused into an RFQ without seriously increasing the beam's emittance. A stepwise continuous HESQ lens has been constructed, and preliminary tests have shown that the structure does provide focusing. In order to understand the transport properties of this device, further detailed studies have been performed. Emittances were measured 3.5 cm from the end of the HESQ at two different voltages on the HESQ electrodes. A comparison of these experimental results with a linear model of the HESQ beam transport is made. 4 refs., 5 figs

Double-photoionization of helium including quadrupole radiation effects

Energy Technology Data Exchange (ETDEWEB)

Colgan, James [Los Alamos National Laboratory; Ludlow, J A [AUBURN UNIV; Lee, Teck - Ghee [AUBURN UNIV; Pindzola, M S [AUBURN UNIV; Robicheaux, F [AUBURN UNIV

2009-01-01

Non-perturbative time-dependent close-coupling calculations are carried out for the double photoionization of helium including both dipole and quadrupole radiation effects. At a photon energy of 800 eV, accessible at CUlTent synchrotron light sources, the quadrupole interaction contributes around 6% to the total integral double photoionization cross section. The pure quadrupole single energy differential cross section shows a local maxima at equal energy sharing, as opposed to the minimum found in the pure dipole single energy differential cross section. The sum of the pure dipole and pure quadrupole single energy differentials is insensitive to non-dipole effects at 800 eV. However, the triple differential cross section at equal energy sharing of the two ejected electrons shows strong non-dipole effects due to the quadrupole interaction that may be experimentally observable.

Design and analysis of linear oscillatory single-phase permanent magnet generator for free-piston stirling engine systems

Science.gov (United States)

Kim, Jeong-Man; Choi, Jang-Young; Lee, Kyu-Seok; Lee, Sung-Ho

2017-05-01

This study focuses on the design and analysis of a linear oscillatory single-phase permanent magnet generator for free-piston stirling engine (FPSE) systems. In order to implement the design of linear oscillatory generator (LOG) for suitable FPSEs, we conducted electromagnetic analysis of LOGs with varying design parameters. Then, detent force analysis was conducted using assisted PM. Using the assisted PM gave us the advantage of using mechanical strength by detent force. To improve the efficiency, we conducted characteristic analysis of eddy-current loss with respect to the PM segment. Finally, the experimental result was analyzed to confirm the prediction of the FEA.

Emittance growth from rotated quadrupoles in heavy ion accelerators

International Nuclear Information System (INIS)

Barnard, J.J.

1995-01-01

We derive a set of moment equations which incorporates linear quadrupolar focusing and space-charge defocusing, in the presence of rotational misalignments of the quadrupoles about the direction of beam propagation. Although the usual beam emittance measured relative to fixed transverse x and y coordinate axes is not constant, a conserved emittance-like quantity has been found. Implications for alignment tolerances in accelerators for heavy-ion inertial fusion are discussed

The Features of Moessbauer Spectra of Hemoglobins: Approximation by Superposition of Quadrupole Doublets or by Quadrupole Splitting Distribution?

International Nuclear Information System (INIS)

Oshtrakh, M. I.; Semionkin, V. A.

2004-01-01

Moessbauer spectra of hemoglobins have some features in the range of liquid nitrogen temperature: a non-Lorentzian asymmetric line shape for oxyhemoglobins and symmetric Lorentzian line shape for deoxyhemoglobins. A comparison of the approximation of the hemoglobin Moessbauer spectra by a superposition of two quadrupole doublets and by a distribution of the quadrupole splitting demonstrates that a superposition of two quadrupole doublets is more reliable and may reflect the non-equivalent iron electronic structure and the stereochemistry in the α- and β-subunits of hemoglobin tetramers.

Noise measurements during high-frequency oscillatory and conventional mechanical ventilation.

Science.gov (United States)

Berens, R J; Weigle, C G

1995-10-01

To evaluate the noise levels with high-frequency oscillatory ventilation and conventional mechanical ventilation. An observational, prospective study. Pediatric intensive care unit. The caretakers and environment of the pediatric intensive care unit. High-frequency oscillatory and conventional mechanical ventilation. Caretakers evaluated noise using a visual analog scale. Noise was measured with a decibel meter and an octave band frequency filter. There was twice as much noise perceived by the caretakers and as measured on the decibel A scale. All measures showed significantly greater noise, especially at low frequencies, with high-frequency oscillatory ventilation. High-frequency oscillatory ventilation exposes the patient to twice as much noise as does the use of conventional mechanical ventilation.

Strobes: An oscillatory combustion

NARCIS (Netherlands)

Corbel, J.M.L.; Lingen, J.N.J. van; Zevenbergen, J.F.; Gijzeman, O.L.J.; Meijerink, A.

2012-01-01

Strobe compositions belong to the class of solid combustions. They are mixtures of powdered ingredients. When ignited, the combustion front evolves in an oscillatory fashion, and flashes of light are produced by intermittence. They have fascinated many scientists since their discovery at the

Thermogravimetric-quadrupole mass-spectrometric analysis of geochemical samples.

Science.gov (United States)

Gibson, E. K., Jr.; Johnson, S. M.

1972-01-01

Thermogravimetric-quadrupole mass-spectrometric-analysis techniques can be used to study a wide variety of problems involving decomposition processes and identification of released volatile components. A recording vacuum thermoanalyzer has been coupled with a quadrupole mass spectrometer. The rapid scan capabilities of the quadrupole mass spectrometer are used to identify the gaseous components released. The capability of the thermogravimetric-quadrupole mass spectrometer to provide analytical data for identification of the released volatile components, for determination of their sequence of release and for correlation of thermal-decomposition studies is illustrated by an analysis of the Orgueil carbonaceous chondrite.

Design of the PEP-II Interaction Region Septum Quadrupole

Science.gov (United States)

Osborn, J.; Tanabe, J.; Yee, D.; Younger, F.

1997-05-01

The PEP-II QF2 magnet is one of the final focus quadrupoles for the Low-Energy Ring (LER) and utilizes a septum aperture to accommodate the adjacent High-Energy Ring (HER) beamline. The LER lattice design specification calls for an extremely high field quality for this magnet. A conventional water-cooled copper coil and laminated steel core design was selected to allow adjustment in the excitation. The close proximity between the LER and HER beamlines and the required integrated quadrupole strength result in a moderately high current density septum design. The QF2 magnets are imbedded in a confined region at each end of the BaBar detector, thus requiring a small magnet core cross section. Pole face windings are included in the QF2 design to buck the skew octupole term induced by the solenoidal fringe field that leaks out of the detector. Back-leg windings are included to buck a small dipole component induced by the lack of perfect quadrupole symmetry in this septum design. 2D pole contour optimization and 3D end chamfers are used to minimize harmonic errors; a separate permanent-magnet Harmonic Corrector Ring compensates for remaining field errors. The design methods and approach, 2D and 3D analyses, and the resulting expected magnet performance are described in this paper.

Disk partition function and oscillatory rolling tachyons

International Nuclear Information System (INIS)

Jokela, Niko; Jaervinen, Matti; Keski-Vakkuri, Esko; Majumder, Jaydeep

2008-01-01

An exact cubic open string field theory rolling tachyon solution was recently found by Kiermaier et al and Schnabl. This oscillatory solution has been argued to be related by a field redefinition to the simple exponential rolling tachyon deformation of boundary conformal theory. In the latter approach, the disk partition function takes a simple form. Out of curiosity, we compute the disk partition function for an oscillatory tachyon profile, and find that the result is nevertheless almost the same

Characterization of Oscillatory Lift in MFC Airfoils

OpenAIRE

Lang Jr, Joseph Reagle

2014-01-01

The purpose of this research is to characterize the response of an airfoil with an oscillatory morphing, Macro-fiber composite (MFC) trailing edge. Correlation of the airfoil lift with the oscillatory input is presented. Modal analysis of the test airfoil and apparatus is used to determine the frequency response function. The effects of static MFC inputs on the FRF are presented and compared to the unactuated airfoil. The transfer function is then used to determine the lift component du...

Mitigating radiation loads in Nb_{3}Sn quadrupoles for the CERN Large Hadron Collider upgrades

Directory of Open Access Journals (Sweden)

N. V. Mokhov

2006-10-01

Full Text Available Challenging beam-induced energy deposition issues are addressed for the next generation of the LHC high-luminosity interaction regions based on Nb_{3}Sn quadrupoles. Detailed mars15 Monte Carlo energy deposition calculations are performed for various coil diameters, thicknesses, and materials of the inner absorber at a field gradient of 200   T/m. It is shown that using the inner absorber made of tungsten-based materials can make the final focus superconducting quadrupoles compatible with a luminosity of 10^{35}   cm^{-2} s^{-1}.

Series fabrication of the main quadrupole cold masses for the LHC begins

CERN Multimedia

2003-01-01

Three hundred and sixty main quadrupole (MQ) magnets will perform the principal beam focusing around the 27 km LHC ring. CERN and CEA-Saclay began collaborating on the development and prototyping of these magnets in 1989. This resulted in five highly successful quadrupole units - also known as short straight sections - one of which was integrated for testing in String 1, and two others of the final design in String 2. Once the tests had confirmed the validity of the design and realization, the fabrication of the 360 cold masses had to be transferred to industry.The German firm ACCEL Instruments was entrusted both with the construction of the quadrupole magnets themselves, and with their assembly into the cold masses together with various combinations of corrector magnets produced by other European manufacturers. Here we see the first of the cold masses containing the MQ magnet of the machine arcs together with two types of corrector magnet ready for shipping to CERN. This first unit was delivered on 12 Februa...

Matter-wave solitons supported by quadrupole-quadrupole interactions and anisotropic discrete lattices

Science.gov (United States)

Zhong, Rong-Xuan; Huang, Nan; Li, Huang-Wu; He, He-Xiang; Lü, Jian-Tao; Huang, Chun-Qing; Chen, Zhao-Pin

2018-04-01

We numerically and analytically investigate the formations and features of two-dimensional discrete Bose-Einstein condensate solitons, which are constructed by quadrupole-quadrupole interactional particles trapped in the tunable anisotropic discrete optical lattices. The square optical lattices in the model can be formed by two pairs of interfering plane waves with different intensities. Two hopping rates of the particles in the orthogonal directions are different, which gives rise to a linear anisotropic system. We find that if all of the pairs of dipole and anti-dipole are perpendicular to the lattice panel and the line connecting the dipole and anti-dipole which compose the quadrupole is parallel to horizontal direction, both the linear anisotropy and the nonlocal nonlinear one can strongly influence the formations of the solitons. There exist three patterns of stable solitons, namely horizontal elongation quasi-one-dimensional discrete solitons, disk-shape isotropic pattern solitons and vertical elongation quasi-continuous solitons. We systematically demonstrate the relationships of chemical potential, size and shape of the soliton with its total norm and vertical hopping rate and analytically reveal the linear dispersion relation for quasi-one-dimensional discrete solitons.

Emergence of Oscillatory Dynamics

DEFF Research Database (Denmark)

Laugesen, Jakob Lund; Mosekilde, Erik

2012-01-01

Besides their systems nature, as described in the preceding chapters, the single most characteristic feature of a living organism is the self-sustained activity it displays in the form of a wide variety of different oscillatory processes [25, 9, 22, 23]. The respiratory cycle and the beating...

Field quality measurements of the LQXB inner triplet quadrupoles for LHC

CERN Document Server

Velev, G V; Carcagno, R; Di Marco, J; Fehér, S; Glass, H; Kashikhin, V V; Kerby, J; Lamm, M J; Makulski, A; Nobrega, A; Nogiec, J; Orris, D; Peterson, T; Rabehl, Roger Jon; Schlabach, P; Strait, J; Sylvester, C D; Tartaglia, M; Tompkins, J C; Zlobin, A V

2005-01-01

As a part of the USLHC program, Fermilab is building half of the inner triplet quadrupole magnets for the LHC. Two identical quadrupoles (MQXB) with a dipole corrector between them in a single cryogenic unit (LQXB) comprise the Q2 optical element of the final focus triplets in the interaction regions. The 5.5 m long MQXB have a 70 mm aperture and operate in superfluid helium at 1.9 K with a peak field gradient of 215 T/m. Manufacturing of the 18 magnets is in an advanced stage. A program of magnetic field quality measurements of the magnets is performed at room temperature during magnet fabrication as well as at superfluid helium temperature during the cold qualification of each magnet. Results of the measurements are summarized in this paper. (12 refs).

Nonuniform radiation damage in permanent magnet quadrupoles.

Science.gov (United States)

Danly, C R; Merrill, F E; Barlow, D; Mariam, F G

2014-08-01

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL's pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

Nonuniform radiation damage in permanent magnet quadrupoles

International Nuclear Information System (INIS)

Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G.

2014-01-01

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components

Nonuniform radiation damage in permanent magnet quadrupoles

Energy Technology Data Exchange (ETDEWEB)

Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

2014-08-15

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

Modification of an achromatic mass spectrometer to include transverse focusing

Energy Technology Data Exchange (ETDEWEB)

Baril, M; Noel, M

1987-08-15

Modification has been made to a magnetic mass spectrometer, comprising a magnetic prism and a parallel plane mirror, to increase its transmission and to obtain a stigmatic image. This has been done by adding two quadrupole lenses, one between the magnetic prism and the mirror to add some focusing in the transverse direction, the other after the mirror to correct the astigmatism created by the first quadrupole lens. In this paper, we derive all the parameters of the quadrupole lenses needed to ensure this objective.

Ion-storage in radiofrequency electric quadrupole field

International Nuclear Information System (INIS)

Gheorghe, V.

1976-01-01

The confinement of charged particles in a quadrupole radiofrequency electric field are presented. The stability diagrams and phase space trajectories for the quadrupole mass spectrometer and for the ion trap are represented and their main characteristics are discussed. (author)

Design and analysis of linear oscillatory single-phase permanent magnet generator for free-piston stirling engine systems

Directory of Open Access Journals (Sweden)

Jeong-Man Kim

2017-05-01

Full Text Available This study focuses on the design and analysis of a linear oscillatory single-phase permanent magnet generator for free-piston stirling engine (FPSE systems. In order to implement the design of linear oscillatory generator (LOG for suitable FPSEs, we conducted electromagnetic analysis of LOGs with varying design parameters. Then, detent force analysis was conducted using assisted PM. Using the assisted PM gave us the advantage of using mechanical strength by detent force. To improve the efficiency, we conducted characteristic analysis of eddy-current loss with respect to the PM segment. Finally, the experimental result was analyzed to confirm the prediction of the FEA.

Slice through an LHC focusing magnet

CERN Multimedia

Slice through an LHC superconducting quadrupole (focusing) magnet. The slice includes a cut through the magnet wiring (niobium titanium), the beampipe and the steel magnet yokes. Particle beams in the Large Hadron Collider (LHC) have the same energy as a high-speed train, squeezed ready for collision into a space narrower than a human hair. Huge forces are needed to control them. Dipole magnets (2 poles) are used to bend the paths of the protons around the 27 km ring. Quadrupole magnets (4 poles) focus the proton beams and squeeze them so that more particles collide when the beams’ paths cross. Bringing beams into collision requires a precision comparable to making two knitting needles collide, launched from either side of the Atlantic Ocean.

Quadrupole moments measured by nuclear orientation

International Nuclear Information System (INIS)

Bouchta, H.

1985-01-01

Quadrupole interactions between the nuclei and solids have been studied with the low temperature nuclear orientation technique. The first series of measurements have been effected on the orientation of 195H g m and 197 Hg m , long lived daughter states in the 195 Au and 197 Au decay. The lifetimes of these states are of the same order as the spin-lattice relaxation time. The reorientation of the intermediate states has been taken into account extending the dipole relaxation mechanism to non-equidistant relaxing substates. The experimental nuclear quadrupole moments, thus deduced are slightly different from theoretical estimations. A new high precision method accessible to levels with 100 ns to 1 m lifetimes, the level mixing resonance on oriented nuclei (LMR/ON) has been elaborated in collaboration with LEUVEN university (Belgium). In this technique the nucleus is subject to a non colinear electric plus magnetic combined interaction. The quadrupole interaction of Ag[7/2, = 40 s] isomer with the electric field gradient in zinc has been established to better than 1% observing its level mixing resonances; and also the ratio of electric field gradients of silver in zinc to cadmium. The electric quadrupole moments of 106 Ag m , 107 Ag m and 109 Ag m have been established combining the level mixing resonances with classical low temperature quadrupole alignment measurements. The experimental values are in good agreement with theoretical calculations based on a semi-microscopical model using Yukawa potential [fr

Low frequency oscillatory flow in a rotating curved pipe

Institute of Scientific and Technical Information of China (English)

陈华军; 章本照; 苏霄燕

2003-01-01

The low frequency oscillatory flow in a rotating curved pipe was studied by using the method of bi-parameter perturbation. Perturbation solutions up to the second order were obtained and the effects of rotationon the low frequency oscillatory flow were examined in detail, The results indicated that there exists evident difference between the low frequency oscillatory flow in a rotating curved pipe and in a curved pipe without ro-tation. During a period, four secondary vortexes may exist on the circular cross-section and the distribution of axial velocity and wall shear stress are related to the ratio of the Coriolis foree to centrifugal foree and the axial pressure gradient.

Low frequency oscillatory flow in a rotating curved pipe

Institute of Scientific and Technical Information of China (English)

陈华军; 章本照; 苏霄燕

2003-01-01

The low frequency oscillatory flow in a rotating curved pipe was studied by using the method of bi-parameter perturbation. Perturbation solutions up to the second order were obtained and the effects of rotation on the low frequency oscillatory flow were examined in detail. The results indicated that there exists evident difference between the low frequency oscillatory flow in a rotating curved pipe and in a curved pipe without rotation. During a period, four secondary vortexes may exist on the circular cross-section and the distribution of axial velocity and wall shear stress are related to the ratio of the Coriolis force to centrifugal force and the axial pressure gradient.

Electron beam final focus system for Thomson scattering at ELBE

Energy Technology Data Exchange (ETDEWEB)

Krämer, J.M., E-mail: jmkr@danfysik.dk [Danfysik A/S, Gregersensvej 8, 2630 Taastrup (Denmark); Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiation Physics, Bautzner Landstrasse 400, 01328 Dresden (Germany); Technische Universität Dresden, 01069 Dresden (Germany); Budde, M.; Bødker, F. [Danfysik A/S, Gregersensvej 8, 2630 Taastrup (Denmark); Irman, A.; Jochmann, A. [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiation Physics, Bautzner Landstrasse 400, 01328 Dresden (Germany); Kristensen, J.P. [Danfysik A/S, Gregersensvej 8, 2630 Taastrup (Denmark); Lehnert, U.; Michel, P. [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiation Physics, Bautzner Landstrasse 400, 01328 Dresden (Germany); Schramm, U. [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiation Physics, Bautzner Landstrasse 400, 01328 Dresden (Germany); Technische Universität Dresden, 01069 Dresden (Germany)

2016-09-11

The design of an electron beam final focus system (FFS) aiming for high-flux laser-Thomson backscattering X-ray sources at ELBE is presented. A telescope system consisting of four permanent magnet based quadrupoles was found to have significantly less chromatic aberrations than a quadrupole doublet or triplet as commonly used. Focusing properties like the position of the focal plane and the spot size are retained for electron beam energies between 20 and 30 MeV by adjusting the position of the quadrupoles individually on a motorized stage. The desired ultra-short electron bunches require an increased relative energy spread up to a few percent and, thus, second order chromatic effects must be taken into account. We also present the design and test results of the permanent magnet quadrupoles. Adjustable shunts allow for correction of the field strength and compensation of deviations in the permanent magnet material. For a beam emittance of 13 mm mrad, we predict focal spot sizes of about 40 μm (rms) and divergences of about 10 mrad using the FFS.

Electron beam final focus system for Thomson scattering at ELBE

CERN Document Server

Krämer, J.M.; Bødker, F.; Irman, A.; .Jochmann A.; Kristensen, J.P.; Lehnert U., HZDR; Michel, P.; Schrammb, U.; 10.1016/j.nima.2015.10.067

2016-01-01

The design of an electron beam final focus system (FFS) aiming for high-flux laser-Thomson backscattering X-ray sources at ELBE is presented. A telescope system consisting of four permanent magnet based quadrupoles was found to have significantly less chromatic aberrations than a quadrupole doublet or triplet as commonly used. Focusing properties like the position of the focal plane and the spot size are retained for electron beam energies between 20 and 30 MeV by adjusting the position of the quadrupoles individually on a motorized stage. The desired ultra-short electron bunches require an increased relative energy spread up to a few percent and, thus, second order chromatic effects must be taken into account. We also present the design and test results of the permanent magnet quadrupoles. Adjustable shunts allow for correction of the field strength and compensation of deviations in the permanent magnet material. For a beam emittance of 13 mm mrad, we predict focal spot sizes of about 40 μm (rms) and diverg...

Electron Beam Final Focus System For Thomson Scattering At Elbe

CERN Document Server

Krämer, J.M.; Bødkera, F.; Irman, A.; Jochmann, A.; Kristensena, J.P.; Lehnert, U.; Michel, P.; Schramm, U.; 10.1016/j.nima.2015.10.067

2016-01-01

The design of an electron beam final focus system (FFS) aiming for high-flux laser-Thomson backscattering X-ray sources at ELBE is presented. A telescope system consisting of four permanent magnet based quadrupoles was found to have significantly less chromatic aberrations than a quadrupole doublet or triplet as commonly used. Focusing properties like the position of the focal plane and the spot size are retained for electron beam energies between 20 and 30 MeV by adjusting the position of the quadrupoles individually on a motorized stage. The desired ultra-short electron bunches require an increased relative energy spread up to a few percent and, thus, second order chromatic effects must be taken into account. We also present the design and test results of the permanent magnet quadrupoles. Adjustable shunts allow for correction of the field strength and compensation of deviations in the permanent magnet material. For a beam emittance of 13 mm mrad, we predict focal spot sizes of about 40 μm (rms) and diverg...

Rescuing the nonjet (NJ) azimuth quadrupole from the flow narrative

Science.gov (United States)

Trainor, Thomas A.

2017-04-01

According to the flow narrative commonly applied to high-energy nuclear collisions a cylindrical-quadrupole component of 1D azimuth angular correlations is conventionally denoted by quantity υ2 and interpreted to represent elliptic flow. Jet angular correlations may also contribute to υ2 data "nonflow" depending on the method used to calculate υ2, but 2D graphical methods are available to insure accurate separation. The nonjet (NJ) quadrupole has various properties inconsistent with a flow interpretation, including the observation that NJ quadrupole centrality variation in A-A collisions has no relation to strongly-varying jet modication ("jet quenching") in those collisions commonly attributed to jet interaction with a flowing dense medium. In this presentation I describe isolation of quadrupole spectra from pt-differential υ2(pt) data from the RHIC and LHC. I demonstrate that quadrupole spectra have characteristics very different from the single-particle spectra for most hadrons, that quadrupole spectra indicate a common boosted hadron source for a small minority of hadrons that "carry" the NJ quadrupole structure, that the narrow source-boost distribution is characteristic of an expanding thin cylindrical shell (strongly contradicting hydro descriptions), and that in the boost frame a single universal quadrupole spectrum (Lévy distribution) on transverse mass mt accurately describes data for several hadron species scaled according to their statistical-model abundances. The quadrupole spectrum shape changes very little from RHIC to LHC energies. Taken in combination those characteristics strongly suggest a unique nonflow (and nonjet) QCD mechanism for the NJ quadrupole conventionally represented by υ2.

Rescuing the nonjet (NJ azimuth quadrupole from the flow narrative

Directory of Open Access Journals (Sweden)

Trainor Thomas A.

2017-01-01

Full Text Available According to the flow narrative commonly applied to high-energy nuclear collisions a cylindrical-quadrupole component of 1D azimuth angular correlations is conventionally denoted by quantity υ2 and interpreted to represent elliptic flow. Jet angular correlations may also contribute to υ2 data “nonflow” depending on the method used to calculate υ2, but 2D graphical methods are available to insure accurate separation. The nonjet (NJ quadrupole has various properties inconsistent with a flow interpretation, including the observation that NJ quadrupole centrality variation in A-A collisions has no relation to strongly-varying jet modication (“jet quenching” in those collisions commonly attributed to jet interaction with a flowing dense medium. In this presentation I describe isolation of quadrupole spectra from pt-differential υ2(pt data from the RHIC and LHC. I demonstrate that quadrupole spectra have characteristics very different from the single-particle spectra for most hadrons, that quadrupole spectra indicate a common boosted hadron source for a small minority of hadrons that “carry” the NJ quadrupole structure, that the narrow source-boost distribution is characteristic of an expanding thin cylindrical shell (strongly contradicting hydro descriptions, and that in the boost frame a single universal quadrupole spectrum (Lévy distribution on transverse mass mt accurately describes data for several hadron species scaled according to their statistical-model abundances. The quadrupole spectrum shape changes very little from RHIC to LHC energies. Taken in combination those characteristics strongly suggest a unique nonflow (and nonjet QCD mechanism for the NJ quadrupole conventionally represented by υ2.

Quadrupole Ion Traps

Indian Academy of Sciences (India)

to do precision spectroscopic measurements on these ions. ... Bonn, investigated the non-magnetic quadrupole mass filter, .... the details of which will be discussed in the subse- ... the radial plane the ion undergoes a circular motion with the.

Excito-oscillatory dynamics as a mechanism of ventricular fibrillation.

Science.gov (United States)

Gray, Richard A; Huelsing, Delilah J

2008-04-01

The instabilities associated with reentrant spiral waves are of paramount importance to the initiation and maintenance of tachyarrhythmias, especially ventricular fibrillation (VF). In addition to tissue heterogeneities, there are only a few basic purported mechanisms of spiral wave breakup, most notably restitution. We test the hypothesis that oscillatory membrane properties act to destabilize spiral waves. We recorded transmembrane potential (V(m)) from isolated rabbit myocytes using a constant current stimulation protocol. We developed a mathematical model that included both the stable excitable equilibrium point at resting V(m) (-80 mV) and the unstable oscillatory equilibrium point at elevated V(m) (-10 mV). Spiral wave dynamics were studied in 2-dimensional grids using variants of the model. All models showed restitution and reproduced the experimental values of transmembrane resistance at rest and during the action potential plateau. Stable spiral waves were observed when the model showed only 1 equilibrium point. However, spatio-temporal complexity was observed if the model showed both excitable and oscillatory equilibrium points (i.e., excito-oscillatory models). The initial wave breaks resulted from oscillatory waves expanding in all directions; after a few beats, the patterns were characterized by a combination of unstable spiral waves and target patterns consistent with the patterns observed on the heart surface during VF. In our model, this VF-like activity only occurred when the single cell period of V(m) oscillations was within a specific range. The VF-like patterns observed in our excito-oscillatory models could not be explained by the existing proposed instability mechanisms. Our results introduce the important suggestion that membrane dynamics responsible for V(m) oscillations at elevated V(m) levels can destabilize spiral waves and thus may be a novel therapeutic target for preventing VF.

Assessment of oscillatory stability constrained available transfer capability

International Nuclear Information System (INIS)

Jain, T.; Singh, S.N.; Srivastava, S.C.

2009-01-01

This paper utilizes a bifurcation approach to compute oscillatory stability constrained available transfer capability (ATC) in an electricity market having bilateral as well as multilateral transactions. Oscillatory instability in non-linear systems can be related to Hopf bifurcation. At the Hopf bifurcation, one pair of the critical eigenvalues of the system Jacobian reaches imaginary axis. A new optimization formulation, including Hopf bifurcation conditions, has been developed in this paper to obtain the dynamic ATC. An oscillatory stability based contingency screening index, which takes into account the impact of transactions on severity of contingency, has been utilized to identify critical contingencies to be considered in determining ATC. The proposed method has been applied for dynamic ATC determination on a 39-bus New England system and a practical 75-bus Indian system considering composite static load as well as dynamic load models. (author)

AA, wide quadrupole on measurement stand

CERN Multimedia

CERN PhotoLab

1981-01-01

Please look up 8101024 first. Shims and washers on the wide quadrupoles (QFW, QDW; located in the lattice where dispersion was large) served mostly for corrections of those lattice parameters which were a function of momentum. After mounting shims and washers, the quadrupoles were measured to determine their magnetic centre and to catalogue the effect of washer constellations. Raymond Brown is busy measuring a wide quad.

AA, shims and washers on quadrupole ends

CERN Multimedia

CERN PhotoLab

1981-01-01

Due to the fact that much of the field of the quadrupoles was outside the iron (in particular with the wide quadrupoles) and that thus the fields of quadrupoles and bending magnets interacted, the lattice properties of the AA could not be predicted with the required accuracy. After a first running period in 1980, during which detailed measurements were made with proton test beams, corrections to the quadrupoles were made in 1981, in the form of laminated shims at the ends of the poles, and with steel washers. With the latter ones, further refinements were made in an iterative procedure with measurements on the circulating beam. This eventually resulted, amongst other things, in a very low chromaticity, with the Q-values being constant to within +- 0.001 over the total momentum range of 6 %. Here we see the shims and washers on a narrow qudrupole (QFN, QDN). See also 8103203, 8103204, 8103205, 8103206.

Oscillatory Convection in Rotating Liquid Metals

Science.gov (United States)

Bertin, Vincent; Grannan, Alex; Aurnou, Jonathan

2016-11-01

We have performed laboratory experiments in a aspect ratio Γ = 2 cylinder using liquid gallium (Pr = 0 . 023) as the working fluid. The Ekman number varies from E = 4 ×10-5 to 4 ×10-6 and the Rayleigh number varies from Ra = 3 ×105 to 2 ×107 . Using heat transfer and temperature measurements within the fluid, we characterize the different styles of low Pr rotating convective flow. The convection threshold is first overcome in the form of a container scale inertial oscillatory mode. At stronger forcing, wall-localized modes develop, coexisting with the inertial oscillatory modes in the bulk. When the strength of the buoyancy increases further, the bulk flow becomes turbulent while the wall modes remain. Our results imply that rotating convective flows in liquid metals do not develop in the form of quasi-steady columns, as in Pr = 1 planetary and stellar dynamo models, but in the form of oscillatory motions. Therefore, convection driven dynamo action in low Pr fluids can differ substantively than that occurring in typical Pr = 1 numerical models. Our results also suggest that low wavenumber, wall modes may be dynamically and observationally important in liquid metal dynamo systems. We thank the NSF Geophysics Program for support of this project.

Generating Low Beta Regions with Quadrupoles for Final Muon Cooling

Energy Technology Data Exchange (ETDEWEB)

Acosta, J. G. [Mississippi U.; Cremaldi, L. M. [Mississippi U.; Hart, T. L. [Mississippi U.; Oliveros, S. J. [Mississippi U.; Summers, D. J. [Mississippi U.; Neuffer, D. V. [Fermilab

2017-05-01

Muon beams and colliders are rich sources of new physics, if muons can be cooled. A normalized rms transverse muon emittance of 280 microns has been achieved in simulation with short solenoids and a betatron function of 3 cm. Here we use ICOOL, G4beamline, and MAD-X to explore using a 400 MeV/c muon beam and strong focusing quadrupoles to approach a normalized transverse emittance of 100 microns and finish 6D muon cooling. The low beta regions produced by the quadrupoles are occupied by dense, low Z absorbers, such as lithium hydride or beryllium, that cool the beam. Equilibrium transverse emittance is linearly proportional to the beta function. Reverse emittance exchange with septa and/or wedges is then used to decrease transverse emittance from 100 to 25 microns at the expense of longitudinal emittance for a high energy lepton collider. Work remains to be done on chromaticity correction.

Oscillatory solutions of the Cauchy problem for linear differential equations

Directory of Open Access Journals (Sweden)

Gro Hovhannisyan

2015-06-01

Full Text Available We consider the Cauchy problem for second and third order linear differential equations with constant complex coefficients. We describe necessary and sufficient conditions on the data for the existence of oscillatory solutions. It is known that in the case of real coefficients the oscillatory behavior of solutions does not depend on initial values, but we show that this is no longer true in the complex case: hence in practice it is possible to control oscillatory behavior by varying the initial conditions. Our Proofs are based on asymptotic analysis of the zeros of solutions, represented as linear combinations of exponential functions.

SCMAG series of programs for calculating superconducting dipole and quadrupole magnets

International Nuclear Information System (INIS)

Green, M.A.

1974-10-01

Programs SCMAG1, SCMAG2, SCMAG3, and SCMAG4 are a group of programs used to design and calculate the characteristics of conductor dominated superconducting dipole and quadrupole magnets. These magnets are used to bend and focus beams of high energy particles and are being used to design the superconducting magnets for the LBL ESCAR accelerator. The four programs are briefly described. (TFD)

CFD Modelling of a Quadrupole Vortex Inside a Cylindrical Channel for Research into Advanced Hybrid Rocket Designs

Science.gov (United States)

Godfrey, B.; Majdalani, J.

2014-11-01

This study relies on computational fluid dynamics (CFD) tools to analyse a possible method for creating a stable quadrupole vortex within a simulated, circular-port, cylindrical rocket chamber. A model of the vortex generator is created in a SolidWorks CAD program and then the grid is generated using the Pointwise mesh generation software. The non-reactive flowfield is simulated using an open source computational program, Stanford University Unstructured (SU2). Subsequent analysis and visualization are performed using ParaView. The vortex generation approach that we employ consists of four tangentially injected monopole vortex generators that are arranged symmetrically with respect to the center of the chamber in such a way to produce a quadrupole vortex with a common downwash. The present investigation focuses on characterizing the flow dynamics so that future investigations can be undertaken with increasing levels of complexity. Our CFD simulations help to elucidate the onset of vortex filaments within the monopole tubes, and the evolution of quadrupole vortices downstream of the injection faceplate. Our results indicate that the quadrupole vortices produced using the present injection pattern can become quickly unstable to the extent of dissipating soon after being introduced into simulated rocket chamber. We conclude that a change in the geometrical configuration will be necessary to produce more stable quadrupoles.

Measurements of quadrupole magnets

International Nuclear Information System (INIS)

Conradie, J.L.; Fourie, D.T.; Cornell, J.C.; Lloyd, G.C.W.

1987-01-01

Measurements carried out on quadrupole magnets using a long asymmetric rotating coil are described. Although the method itself is fairly well-known, the introduction of microprocessors has made this once-tedious technique into a useful and simple method of evaluating quadrupole magnets. The rotating-coil device and a variety of coil sizes are now commercially available. The coil contains a large number of extremely fine wires, embedded in a carefully balanced fibre-glass rotor, resulting in a reasonable induced voltage when the coil is rotated. A digital harmonic analyser is then used to obtain the integrated multipole content of the waveform, while the coil is rotating. By integrating over time, one can average out random noise and increase the reliability and repeatability of the measurements. Because the harmonic analysis is done in real time, the method is quick, easy and accurate, and has been extended to locate the precise magnetic centre of the quadrupole magnet by adjusting its position relative to the coil axis so as to minimize the dipole content of the output waveform. Results of these measurements are compared with those obtained with an optical method using a suspension of magnetite. The observed light pattern is explained analytically. (author)

Design of permanent magnet quadrupole for LEHIPA DTL

International Nuclear Information System (INIS)

Mathew, Jose V.; Rao, S.V.L.S.; Krishnagopal, S.; Singh, P.

2011-01-01

The drift tube linac (DTL) of the low energy high intensity proton accelerator (LEHIPA) has been designed to accelerate 30 mA proton beam from 3 MeV to 20 MeV in a distance of around 13 m. A FFDD lattice structure is selected to provide strong transverse focusing, where each drift tube includes one quadrupole magnet. Beam dynamics simulations specified an effective magnet length of 47 mm, maximum field gradient of 47 T/m, and bore aperture of 24 mm. For these specifications, a detailed design of a very thin permanent magnet quadrupole (PMQ) is presented. Four types of PMQ designs have been compared: a 16-segment trapezoidal design in the Halbach configuration, two 16-segment rectangular designs (with and without gaps), and an 8-segment rectangular design. 2D and 3D modeling codes, POISSON and CST Studio suite are used for the design studies. The good field region is calculated based on field gradient deviation in the transverse plane and integral field homogeneity. The very low aspect ratio of these PMQs leads to edge effects, thereby reducing the central field strength. The 3D simulations are used to study these edge effects. (author)

On oscillatory microstructure during cellular growth of directionally solidified Sn–36at.%Ni peritectic alloy

Science.gov (United States)

Peng, Peng; Li, Xinzhong; Li, Jiangong; Su, Yanqing; Guo, Jingjie

2016-01-01

An oscillatory microstructure has been observed during deep-cellular growth of directionally solidified Sn–36at.%Ni hyperperitectic alloy containing intermetallic compounds with narrow solubility range. This oscillatory microstructure with a dimension of tens of micrometers has been observed for the first time. The morphology of this wave-like oscillatory structure is similar to secondary dendrite arms, and can be observed only in some local positions of the sample. Through analysis such as successive sectioning of the sample, it can be concluded that this oscillatory microstructure is caused by oscillatory convection of the mushy zone during solidification. And the influence of convection on this oscillatory microstructure was characterized through comparison between experimental and calculations results on the wavelength. Besides, the change in morphology of this oscillatory microstructure has been proved to be caused by peritectic transformation during solidification. Furthermore, the melt concentration increases continuously during solidification of intermetallic compounds with narrow solubility range, which helps formation of this oscillatory microstructure. PMID:27066761

On oscillatory microstructure during cellular growth of directionally solidified Sn-36at.%Ni peritectic alloy.

Science.gov (United States)

Peng, Peng; Li, Xinzhong; Li, Jiangong; Su, Yanqing; Guo, Jingjie

2016-04-12

An oscillatory microstructure has been observed during deep-cellular growth of directionally solidified Sn-36at.%Ni hyperperitectic alloy containing intermetallic compounds with narrow solubility range. This oscillatory microstructure with a dimension of tens of micrometers has been observed for the first time. The morphology of this wave-like oscillatory structure is similar to secondary dendrite arms, and can be observed only in some local positions of the sample. Through analysis such as successive sectioning of the sample, it can be concluded that this oscillatory microstructure is caused by oscillatory convection of the mushy zone during solidification. And the influence of convection on this oscillatory microstructure was characterized through comparison between experimental and calculations results on the wavelength. Besides, the change in morphology of this oscillatory microstructure has been proved to be caused by peritectic transformation during solidification. Furthermore, the melt concentration increases continuously during solidification of intermetallic compounds with narrow solubility range, which helps formation of this oscillatory microstructure.

Coil End Optimization of the Nb$_3$Sn Quadrupole for the High Luminosity LHC

CERN Document Server

Izquierdo Bermudez, S; Bossert, R; Cheng, D; Ferracin, P; Krave, ST; Perez, J C; Schmalzle, J; Yu, M

2015-01-01

As part of the Large Hadron Collider Luminosity upgrade (HiLumi-LHC) program, the US LARP collaboration and CERN are working together to design and build a 150 mm aperture quadrupole magnet that aims at providing a nominal gradient of 140 T/m. The resulting conductor peak field of more than 12 T requires the use of Nb$_{3}$Sn superconducting coils. In this paper the coil design for the quadrupole short model (SQXF) is described, focusing in particular on the optimization of the end-parts. We first describe the magnetic optimization aiming at reducing the peak field enhancement in the ends and minimizing the integrated multipole content. Then we focus on the analysis and tests performed to determine the most suitable shapes of end turns and spacers, minimizing the mechanical stress on the cables. We conclude with a detailed description of the baseline end design for the first series of the short model coils.

Power supplies for the injector synchrotron quadrupoles and sextupoles

International Nuclear Information System (INIS)

Fathizadeh, M.

1995-01-01

This light source note will describe the power supplies for the injector synchrotron quadrupole and sextupole magnets. The injector synchrotron has two families of quadrupole magnets. Each family consists of 40 quadrupole magnets connected in series. These magnets are energized by two phase-controlled, 12-pulse power supplies. Therefore, each power supply will be rated to deliver the necessary power to only 40 quadrupole magnets. The two families of sextupole magnets in the injector synchrotron each consists of 32 sextupole magnets connected in series, powered by a phase-controlled power supply. Thus, each power supply shall be capable of delivering power to only 32 sextupole magnets

Design and field measurement of the BEPC-II interaction region dual-aperture quadrupoles

International Nuclear Information System (INIS)

Yin, Z.S.; Wu, Y.Z.; Zhang, J.F.; Chen, W.; Li, Y.J.; Li, L.; Hou, R.; Yin, B.G.; Sun, X.J.; Ren, F.L.; Wang, F.A.; Chen, F.S.; Yu, C.H.; Chen, C.

2007-01-01

With the Beijing Electron Positron Collider upgrade project (BEPC-II), two dual-aperture septum-style quadrupole magnets are used in the interaction region for the final focusing of the electron and positron beams. The BEPC-II lattice design calls for the same high quality integral quadrupole field and large good field region in both apertures for each magnet. Two-dimensional contour optimization and pole-end chamfer iteration are used to minimize the systematic harmonic errors. Unexpected non-systematic errors induced by the unsymmetrical structure and the manufacturing errors are compensated with the pole-end shimming. Magnet measurements with rotating coils are performed to guide and confirm the magnet design. This paper discusses the design consideration, optimizing procedure and measurement results of these dual-aperture magnets

Integrated design of superconducting accelerator magnets. A case study of the main quadrupole

International Nuclear Information System (INIS)

Russenschuck, S.; Calmon, F.; Lewin, M.; Paul, C.; Ramberger, S.; Rodriguez-Mateos, F.; Tortschanoff, T.; Verweij, A.; Wolf, R.

1998-01-01

This paper describes the software tool which has been developed for the design of the superconducting magnets for the large hadron collider (LHC) at CERN. Applied methods include numerical field calculation with a reduced vector-potential formulation, the application of vector-optimization methods, and the use of genetic as well as deterministic minimization algorithms. Together with the applied concept of features, the software tool is used as an approach towards integrated design of superconducting magnets. The main quadrupole magnet for the LHC, which was designed at CEA Saclay (France) using a different approach, was chosen as an example for the integrated design process. The paper focuses on the design issues and is not a project report on the main quadrupoles under construction. (orig.)

Design of the dipole and quadrupole magnets of the dedicated proton synchrotron for hadron therapy

International Nuclear Information System (INIS)

Kukarnikov, S.I.; Makoveev, V.K.; Minashkin, V.F.; Molodozhentsev, A.Yu.; Shevtsov, V.F.; Sidorov, G.I.

1998-01-01

The 2D-calculation results of magnetic elements of the PRAMES (Prague Medical Synchrotron) are presented. This machine is a dedicated accelerator for cancer therapy. The output energy of the beam should be variable in the range 60-220 MeV. The maximum magnetic field of the dipole magnet should be 1.2 T, the maximum magnetic field ramp - less than 8 T/s. The focusing structure of the proton synchrotron consists of 8 dipole and 18 quadrupole magnets. All magnets are laminated to minimize leakage currents. The dipoles are parallel-edge, H-type magnets. The field uniformity should be of the order of ± 1 x 10 -4 in the working area (± 63 mm and ± 27 mm in the horizontal and vertical planes, respectively). The maximum magnetic field on the pole of the quadrupole lenses should be less than 1 T. The gradient uniformity of quadrupole magnets in the working region should be less than ± 3.5 x 10 -4

Beam self-excited rf cavity driver for a deflector or focusing system

International Nuclear Information System (INIS)

Wadlinger, E.A.

1996-01-01

A bunched beam from an accelerator can excite and power an rf cavity which then drives either a deflecting or focusing (including nonlinear focusing) rf cavity with an amplitude related to beam current. Rf power, generated when a bunched beam loses energy to an rf field when traversing an electric field that opposes the particle's motion, is used to drive a separate (or the same) cavity to either focus or deflect the beam. The deflected beam can be stopped by an aperture or directed to a different area of a target depending on beam current. The beam-generated rf power can drive a radiofrequency quadrupole that can change the focusing properties of a beam channel as a function of beam current (space-charge-force compensation or modifying the beam distribution on a target). An rf deflector can offset a beam to a downstream sextupole, effectively producing a position-dependent quadrupole field. The combination of rf deflector plus sextupole will produce a beam current dependent quadrupole-focusing force. A static quadrupole magnet plus another rf deflector can place the beam back on the optic axis. This paper describes the concept, derives the appropriate equations for system analysis, and gives examples. A variation on this theme is to use the wake field generated in an rf cavity to cause growth in the beam emittance. The beam current would then be apertured by emittance defining slits. (author)

Compact quadrupole triplet for the S-DALINAC polarized electron injector SPIN

Energy Technology Data Exchange (ETDEWEB)

Eckardt, C.; Eichhorn, R.; Enders, J.; Hessler, C.; Poltoratska, Y. [Inst. fuer Kernphysik, Technische Univ. Darmstadt (Germany); Ackermann, W.; Mueller, W.F.O.; Steiner, B.; Weiland, T. [Inst. fuer Theorie Elektromagnetischer Felder, Technische Univ. Darmstadt (Germany)

2007-07-01

An ultra compact quadrupole triplet for the S-DALINAC Polarized Electron Injector SPIN has been developed. This development is due to limiting spatial restrictions. Each individual quadrupole has a length of 8 mm, affixed by two 2 mm aluminum plates, resulting in a length of only 12 mm per quadrupole. The gaps between each quadrupole are set to 18 mm, therefore the complete triplet has a total length of only 72 mm. The quadrupole design includes a large aperture, suitable for CF 35 beam pipes. As fringe fields reach far info neighboring yokes, the assembly requires simulation by a beam dynamics tool for optimal weighting of the current excitation. Measurement of the magnetic field distribution is compared to numerical values and the quadrupole strength is calculated. (orig.)

Permanent magnet quadrupole for the 1-ST tank of LINAC-4

CERN Document Server

Skachkov, Vl; Sergeeva, O; Lombardi, A; Sargsyan, E; Cornuet, D; Venturini , W; Skachkov , V

2006-01-01

A rare-earth (REPM) ∅ 60 mm diameter, 45 mm long quadrupole for the LINAC-4 focusing channel with an integrated gradient of 2.3 T is described. Thin side washers are used for tuning the quad into specified gradient integral with ±0.5 % accuracy. The single washer contribution calculations are discussed. A method for limiting to 30 μ m the magnetic axis offset in the REPM quad is discussed to exclude its compensation by the outer diameter machining before inserting into the drift tube. Nonlinearity of the field is less than 1 % in the reference range of 75 % of beam aperture at the central cross- section near the quad axis . The angular quadrupole arrangement in the drift tube will be provided by machining the main groove on the quad surface in the median plane with 1 mrad accuracy. Calculations of the longitudinal gradient distribution between two...

The giant quadrupole resonance in highly excited rotating nuclei

International Nuclear Information System (INIS)

Civitarese, O.; Furui, S.; Ploszajczak, M.; Faessler, A.

1983-01-01

The giant quadrupole resonance in highly excited, fast rotating nuclei is studied as a function of both the nuclear temperature and the nuclear angular momentum. The photo-absorption cross sections for quadrupole radiation in 156 Dy, 160 Er and 164 Er are evaluated within the linear response theory. The strength functions of the γ-ray spectrum obtained from the decay of highly excited nuclear states by deexcitation of the isoscalar quadrupole mode show a fine structure, which depends on the temperature T, the angular momentum I and the deformation of the nucleus β. The splitting of the modes associated with the signature-conserving and signature-changing components of the quadrupole field is discussed. (orig.)

Electromagnetic design of superconducting quadrupoles

Directory of Open Access Journals (Sweden)

L. Rossi

2006-10-01

Full Text Available We study how the critical gradient depends on the coil layout in a superconducting quadrupole for particle accelerators. We show that the results relative to a simple sector coil are well representative of the coil layouts that have been used to build several quadrupoles in the past 30 years. Using a semianalytical approach, we derive a formula that gives the critical gradient as a function of the coil cross-sectional area, of the magnet aperture, and of the superconducting cable parameters. This formula is used to evaluate the efficiency of several types of coil layouts (shell, racetrack, block, open midplane.

Design and alaysis of the PEP-II B-Factory HER QF5 quadrupole magnet

International Nuclear Information System (INIS)

Kendall, C.M.; Harvey, A.; Swan, J.; Yamamoto, R.; Yokota, T.; Tanabe, J.; Sullivan, M.; Wienands, U.

1997-01-01

The High Energy Ring (HER) in Stanford Linear Accelerator Center's PEP-II B-Factory employs two high field quality quadrupole magnets, labeled QF5, located in the Interaction Region (IR) symmetrically about the Interaction Point (IP), for final horizontal beam focusing. An asymmetric, septum, Collins quadrupole design is required for QF5 as a result of space constraints within the IR. Water cooled square hollow copper conductor is used in a two coil per pole configuration to develop the 61.7 kG/m and 82.2 kG/m gradients required for the HER 9 GeV and 12 GeV energy levels respectively. A 1.45 m long laminated iron core constructed in two halves with a 160 mm diameter aperture and pole tip shims shape the quadruple field. The QF5 field quality requirements include a multipole content of b n /b 2 ≤1 x 10 -4 for n = 3-15 at a radius of 78.1 mm. The QF5 quadrupole mechanical and magnetic design and analysis are presented

Two-scale approach to oscillatory singularly perturbed transport equations

CERN Document Server

Frénod, Emmanuel

2017-01-01

This book presents the classical results of the two-scale convergence theory and explains – using several figures – why it works. It then shows how to use this theory to homogenize ordinary differential equations with oscillating coefficients as well as oscillatory singularly perturbed ordinary differential equations. In addition, it explores the homogenization of hyperbolic partial differential equations with oscillating coefficients and linear oscillatory singularly perturbed hyperbolic partial differential equations. Further, it introduces readers to the two-scale numerical methods that can be built from the previous approaches to solve oscillatory singularly perturbed transport equations (ODE and hyperbolic PDE) and demonstrates how they can be used efficiently. This book appeals to master’s and PhD students interested in homogenization and numerics, as well as to the Iter community.

Boson models of quadrupole collective motion

International Nuclear Information System (INIS)

Zelevinskij, V.G.

1985-01-01

The subject of the lecture is the low-lying excitations of even-even (e-e) spherical nuclei. The predominant role of the quadrupole mode, which determines the structure of spectra and transitions, is obvious on the background of shell periodicity and pair correlations. Typical E2-transitions are strengthened Ω ∼ A 2/3 times in comparison with single particle evaluations. Together with the regularity of the whole picture it gives evidence about collectivization of quadrupole motion. The collective states are combined in bands, where the transition probability are especially great; frequencies ω of the strengthened transitions are small in comparison with pair separation energies of 2 E-bar ∼ 2 MeV. Thus, the description of low-lying excitations of spherical nuclei has to be based on three principles: collectivity (Ω >> 1), adiabaticity (τ ≡ ω/2E-bar << 1) and quadrupole symmetry

Three-dimensional Oscillatory Magnetic Reconnection

Energy Technology Data Exchange (ETDEWEB)

Thurgood, Jonathan O.; McLaughlin, James A. [Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle upon Tyne, NE1 1ST (United Kingdom); Pontin, David I., E-mail: jonathan.thurgood@northumbria.ac.uk [Division of Mathematics, University of Dundee, Dundee, DD1 4HN (United Kingdom)

2017-07-20

Here we detail the dynamic evolution of localized reconnection regions about 3D magnetic null points using numerical simulation. We demonstrate for the first time that reconnection triggered by the localized collapse of a 3D null point that is due to an external magnetohydrodynamic (MHD) wave involves a self-generated oscillation, whereby the current sheet and outflow jets undergo a reconnection reversal process during which back-pressure formation at the jet heads acts to prise open the collapsed field before overshooting the equilibrium into an opposite-polarity configuration. The discovery that reconnection at fully 3D nulls can proceed naturally in a time-dependent and periodic fashion suggests that oscillatory reconnection mechanisms may play a role in explaining periodicity in astrophysical phenomena associated with magnetic reconnection, such as the observed quasi-periodicity of solar and stellar flare emission. Furthermore, we find that a consequence of oscillatory reconnection is the generation of a plethora of freely propagating MHD waves that escape the vicinity of the reconnection region.

Three-dimensional Oscillatory Magnetic Reconnection

International Nuclear Information System (INIS)

Thurgood, Jonathan O.; McLaughlin, James A.; Pontin, David I.

2017-01-01

Here we detail the dynamic evolution of localized reconnection regions about 3D magnetic null points using numerical simulation. We demonstrate for the first time that reconnection triggered by the localized collapse of a 3D null point that is due to an external magnetohydrodynamic (MHD) wave involves a self-generated oscillation, whereby the current sheet and outflow jets undergo a reconnection reversal process during which back-pressure formation at the jet heads acts to prise open the collapsed field before overshooting the equilibrium into an opposite-polarity configuration. The discovery that reconnection at fully 3D nulls can proceed naturally in a time-dependent and periodic fashion suggests that oscillatory reconnection mechanisms may play a role in explaining periodicity in astrophysical phenomena associated with magnetic reconnection, such as the observed quasi-periodicity of solar and stellar flare emission. Furthermore, we find that a consequence of oscillatory reconnection is the generation of a plethora of freely propagating MHD waves that escape the vicinity of the reconnection region.

Nuclear electric quadrupole interactions in liquids entrapped in cavities

Energy Technology Data Exchange (ETDEWEB)

Furman, Gregory B., E-mail: gregoryf@bgu.ac.il; Meerovich, Victor M.; Sokolovsky, Vladimir L. [Ben Gurion University of the Negev, Physics Department (Israel)

2016-12-15

Liquids entrapped in cavities and containing quadrupole nuclei are considered. The interaction of the quadrupole moment of a nucleus with the electric field gradient is studied. In such a system, molecules are in both rotational and translational Brownian motions which are described by the diffusion equation. Solving this equation, we show that the intra- and intermolecular nuclear quadrupole interactions are averaged to zero in cavities with the size larger than several angstroms.

PRINCIPLE OF SKEW QUADRUPOLE MODULATION TO MEASURE BETATRON COUPLING

International Nuclear Information System (INIS)

LUO, Y.; PILAT, F.; ROSER, T.

2004-01-01

The measurement of the residual betatron coupling via skew quadrupole modulation is a new diagnostics technique that has been developed and tested at the Relativistic Heavy Ion Collider (RHIC) as a very promising method for the linear decoupling on the ramp. By modulating the strengths of different skew quadrupole families the two eigentunes are precisely measured with the phase lock loop system. The projections of the residual coupling coefficient onto the skew quadrupole coupling modulation directions are determined. The residual linear coupling could be corrected according to the measurement. An analytical solution for skew quadrupole modulation based on Hamiltonian perturbation approximation is given, and simulation code using smooth accelerator model is also developed. Some issues concerning the practical applications of this technique are discussed

Oscillations during observations: Dynamic oscillatory networks serving visuospatial attention.

Science.gov (United States)

Wiesman, Alex I; Heinrichs-Graham, Elizabeth; Proskovec, Amy L; McDermott, Timothy J; Wilson, Tony W

2017-10-01

The dynamic allocation of neural resources to discrete features within a visual scene enables us to react quickly and accurately to salient environmental circumstances. A network of bilateral cortical regions is known to subserve such visuospatial attention functions; however the oscillatory and functional connectivity dynamics of information coding within this network are not fully understood. Particularly, the coding of information within prototypical attention-network hubs and the subsecond functional connections formed between these hubs have not been adequately characterized. Herein, we use the precise temporal resolution of magnetoencephalography (MEG) to define spectrally specific functional nodes and connections that underlie the deployment of attention in visual space. Twenty-three healthy young adults completed a visuospatial discrimination task designed to elicit multispectral activity in visual cortex during MEG, and the resulting data were preprocessed and reconstructed in the time-frequency domain. Oscillatory responses were projected to the cortical surface using a beamformer, and time series were extracted from peak voxels to examine their temporal evolution. Dynamic functional connectivity was then computed between nodes within each frequency band of interest. We find that visual attention network nodes are defined functionally by oscillatory frequency, that the allocation of attention to the visual space dynamically modulates functional connectivity between these regions on a millisecond timescale, and that these modulations significantly correlate with performance on a spatial discrimination task. We conclude that functional hubs underlying visuospatial attention are segregated not only anatomically but also by oscillatory frequency, and importantly that these oscillatory signatures promote dynamic communication between these hubs. Hum Brain Mapp 38:5128-5140, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Beam-based alignment of C-shaped quadrupole magnets

International Nuclear Information System (INIS)

Portmann, G.; Robin, D.

1998-06-01

Many storage rings have implemented a method of finding the positional offset between the electrical center of the beam position monitors (BPM) and the magnetic center of the adjacent quadrupole magnets. The algorithm for accomplishing this is usually based on modulating the current in the quadrupole magnet and finding the beam position that minimizes the orbit perturbation. When the quadrupole magnet is C-shaped, as it is for many light sources, the modulation method can produce an erroneous measurement of the magnetic center in the horizontal plane. When the current in a C-shaped quadrupole is changed, there is an additional dipole component in the vertical field. Due to nonlinearities in the hysteresis cycle of the C-magnet geometry, the beam-based alignment technique at the Advanced Light Source (ALS) deviated horizontally by .5 mm from the actual magnetic center. By modifying the technique, the offsets were measured to an accuracy of better than 50 microm

Focus Article: Oscillatory and long-range monotonic exponential decays of electrostatic interactions in ionic liquids and other electrolytes: The significance of dielectric permittivity and renormalized charges

Science.gov (United States)

Kjellander, Roland

2018-05-01

A unified treatment of oscillatory and monotonic exponential decays of interactions in electrolytes is displayed, which highlights the role of dielectric response of the fluid in terms of renormalized (effective) dielectric permittivity and charges. An exact, but physically transparent statistical mechanical formalism is thereby used, which is presented in a systematic, pedagogical manner. Both the oscillatory and monotonic behaviors are given by an equation for the decay length of screened electrostatic interactions that is very similar to the classical expression for the Debye length. The renormalized dielectric permittivities, which have similar roles for electrolytes as the dielectric constant has for pure polar fluids, consist in general of several entities with different physical meanings. They are connected to dielectric response of the fluid on the same length scale as the decay length of the screened interactions. Only in cases where the decay length is very long, these permittivities correspond approximately to a dielectric response in the long-wavelength limit, like the dielectric constant for polar fluids. Experimentally observed long-range exponentially decaying surface forces are analyzed as well as the oscillatory forces observed for short to intermediate surface separations. Both occur in some ionic liquids and in concentrated as well as very dilute electrolyte solutions. The coexisting modes of decay are in general determined by the bulk properties of the fluid and not by the solvation of the surfaces; in the present cases, they are given by the behavior of the screened Coulomb interaction of the bulk fluid. The surface-fluid interactions influence the amplitudes and signs or phases of the different modes of the decay, but not their decay lengths and wavelengths. The similarities between some ionic liquids and very dilute electrolyte solutions as regards both the long-range monotonic and the oscillatory decays are analyzed.

Radio frequency focused interdigital linear accelerator

Science.gov (United States)

Swenson, Donald A.; Starling, W. Joel

2006-08-29

An interdigital (Wideroe) linear accelerator employing drift tubes, and associated support stems that couple to both the longitudinal and support stem electromagnetic fields of the linac, creating rf quadrupole fields along the axis of the linac to provide transverse focusing for the particle beam. Each drift tube comprises two separate electrodes operating at different electrical potentials as determined by cavity rf fields. Each electrode supports two fingers, pointing towards the opposite end of the drift tube, forming a four-finger geometry that produces an rf quadrupole field distribution along its axis. The fundamental periodicity of the structure is equal to one half of the particle wavelength .beta..lamda., where .beta. is the particle velocity in units of the velocity of light and .lamda. is the free space wavelength of the rf. Particles are accelerated in the gaps between drift tubes. The particle beam is focused in regions inside the drift tubes.

Variable-field permanent-magnet quadrupole for the SSC

International Nuclear Information System (INIS)

Barlow, D.B.; Kraus, R.H. Jr.; Martinez, R.P.; Meyer, R.E.

1994-01-01

A set of compact variable-field permanent-magnet quadrupoles have been designed, fabricated, and tested for use in the SSC linac matching section. The quadrupoles have 24 mm-diameter apertures and 40 mm-long poles. The hybrid (permanent-magnet and iron) design, uses a fixed core of magnet material (NdFeB) and iron (C-1006) surrounded by a rotating ring of the same magnet material and iron. The quadrupole gradient-length product can be smoothly varied from a minimum of 0.7 T up to a maximum of 4.3 T by a 90 degree rotation of the outer ring of iron and magnet material

Variable-field permanent magnet quadrupole for the SSC

International Nuclear Information System (INIS)

Barlow, D.B.; Kraus, R.H. Jr.; Martinez, R.P.; Meyer, R.E.

1993-01-01

A set of compact variable-field permanent-magnet quadrupoles have been designed, fabricated, and tested for use In the SSC linac matching section. The quadrupoles have 24 mm-diameter apertures and 40 mm-long poles. The hybrid (permanent-magnet and iron) design, uses a fixed core of magnet material (NdFeB) and iron (C-1006) surrounded by a rotating ring of the same magnet material and iron. The quadrupole gradient-length product can be smoothly varied from a minimum of 0.7 T up to a maximum, of 4.3 T by a 90 degrees rotation of the outer ring of iron and magnet material

Electron Cloud Generation and Trapping in a Quadrupole Magnet at the Los Alamos Proton Storage Ring

International Nuclear Information System (INIS)

Macek, Robert J.; Browman, Andrew A.; Ledford, John E.; TechSource, Santa Fe; Los Alamos; Borden, Michael J.; O'Hara, James F.; McCrady, Rodney C.; Rybarcyk, Lawrence J.; Spickermann, Thomas; Zaugg, Thomas J.; Pivi, Mauro T.F.

2008-01-01

Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR) have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the 'prompt' electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the 'swept' electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100 (micro)s. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the quadrupole

Electron cloud generation and trapping in a quadrupole magnet at the Los Alamos proton storage ring

Directory of Open Access Journals (Sweden)

Robert J. Macek

2008-01-01

Full Text Available Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the “prompt” electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the “swept” electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100  μs. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the quadrupole.

ISR Superconducting Quadrupoles

CERN Multimedia

1977-01-01

Michel Bouvier is preparing for curing the 6-pole superconducting windings inbedded in the cylindrical wall separating liquid helium from vacuum in the quadrupole aperture. The heat for curing the epoxy glue was provided by a ramp of infrared lamps which can be seen above the slowly rotating cylinder. See also 7703512X, 7702690X.

Random errors in the magnetic field coefficients of superconducting quadrupole magnets

International Nuclear Information System (INIS)

Herrera, J.; Hogue, R.; Prodell, A.; Thompson, P.; Wanderer, P.; Willen, E.

1987-01-01

The random multipole errors of superconducting quadrupoles are studied. For analyzing the multipoles which arise due to random variations in the size and locations of the current blocks, a model is outlined which gives the fractional field coefficients from the current distributions. With this approach, based on the symmetries of the quadrupole magnet, estimates are obtained of the random multipole errors for the arc quadrupoles envisioned for the Relativistic Heavy Ion Collider and for a single-layer quadrupole proposed for the Superconducting Super Collider

Skyrme's interaction beyond the mean-field. The DGCM+GOA Hamiltonian of nuclear quadrupole motion

International Nuclear Information System (INIS)

Kluepfel, Peter

2008-01-01

This work focuses on the microscopic description of nuclear collective quadrupole motion within the framework of the dynamic Generator-Coordinate-Method(DGCM)+Gaussian-Overlap-Approximation(GOA). Skyrme-type effective interactions are used as the fundamental many-particle interaction. Starting from a rotational invariant, polynomial and topologic consistent formulation of the GCM+GOA Hamiltonian an interpolation scheme for the collective masses and potential is developed. It allows to define the collective Hamiltonian of fully triaxial collective quadrupole dynamics from a purely axial symmetric configuration space. The substantial gain in performance allows the self-consistent evaluation of the dynamic quadrupole mass within the ATDHF-cranking model. This work presents the first large-scale analysis of quadrupole correlation energies and lowlying collective states within the DGCM+GOA model. Different Skyrme- and pairing interactions are compared from old standards up to more recent parameterizations. After checking the validity of several approximations to the DGCM+GOA model - both on the mean-field and the collective level - we proceed with a detailed investigation of correlation effects along the chains of semi-magic isotopes and isotones. This finally allows to define a set of observables which are hardly affected by collective correlations. Those observables were used for a refit of a Skyrme-type effective interaction which is expected to cure most of the problems of the recent parameterizations. Preparing further work, estimates for the correlated ground state energy are proposed which can be evaluated directly from the mean-field model. (orig.)

Skyrme's interaction beyond the mean-field. The DGCM+GOA Hamiltonian of nuclear quadrupole motion

Energy Technology Data Exchange (ETDEWEB)

Kluepfel, Peter

2008-07-29

This work focuses on the microscopic description of nuclear collective quadrupole motion within the framework of the dynamic Generator-Coordinate-Method(DGCM)+Gaussian-Overlap-Approximation(GOA). Skyrme-type effective interactions are used as the fundamental many-particle interaction. Starting from a rotational invariant, polynomial and topologic consistent formulation of the GCM+GOA Hamiltonian an interpolation scheme for the collective masses and potential is developed. It allows to define the collective Hamiltonian of fully triaxial collective quadrupole dynamics from a purely axial symmetric configuration space. The substantial gain in performance allows the self-consistent evaluation of the dynamic quadrupole mass within the ATDHF-cranking model. This work presents the first large-scale analysis of quadrupole correlation energies and lowlying collective states within the DGCM+GOA model. Different Skyrme- and pairing interactions are compared from old standards up to more recent parameterizations. After checking the validity of several approximations to the DGCM+GOA model - both on the mean-field and the collective level - we proceed with a detailed investigation of correlation effects along the chains of semi-magic isotopes and isotones. This finally allows to define a set of observables which are hardly affected by collective correlations. Those observables were used for a refit of a Skyrme-type effective interaction which is expected to cure most of the problems of the recent parameterizations. Preparing further work, estimates for the correlated ground state energy are proposed which can be evaluated directly from the mean-field model. (orig.)

Oscillatory Stability and Eigenvalue Sensitivity Analysis of A DFIG Wind Turbine System

DEFF Research Database (Denmark)

Yang, Lihui; Xu, Zhao; Østergaard, Jacob

2011-01-01

This paper focuses on modeling and oscillatory stability analysis of a wind turbine with doubly fed induction generator (DFIG). A detailed mathematical model of DFIG wind turbine with vector-control loops is developed, based on which the loci of the system Jacobian's eigenvalues have been analyzed......, showing that, without appropriate controller tuning a Hopf bifurcation can occur in such a system due to various factors, such as wind speed. Subsequently, eigenvalue sensitivity with respect to machine and control parameters is performed to assess their impacts on system stability. Moreover, the Hopf...

Tunable high-gradient permanent magnet quadrupoles

CERN Document Server

Shepherd, B J A; Marks, N; Collomb, N A; Stokes, D G; Modena, M; Struik, M; Bartalesi, A

2014-01-01

A novel type of highly tunable permanent magnet (PM) based quadrupole has been designed by the ZEPTO collaboration. A prototype of the design (ZEPTO-Q1), intended to match the specification for the CLIC Drive Beam Decelerator, was built and magnetically measured at Daresbury Laboratory and CERN. The prototype utilises two pairs of PMs which move in opposite directions along a single vertical axis to produce a quadrupole gradient variable between 15 and 60 T/m. The prototype meets CLIC's challenging specification in terms of the strength and tunability of the magnet.

Initial value gravitational quadrupole radiation theorem

International Nuclear Information System (INIS)

Winicour, J.

1987-01-01

A rigorous version of the quadrupole radiation formula is derived using the characteristic initial value formulation of a general relativistic fluid space-time. Starting from initial data for a Newtonian fluid, an algorithm is presented that determines characteristic initial data for a one-parameter family of general relativistic fluid space-times. At the initial time, a one-parameter family of space-times with this initial data osculates the evolution of the Newtonian fluid and has leading order news function equal to the third time derivative of the transverse Newtonian quadrupole moment

The stabilisation of final focus system

Indian Academy of Sciences (India)

The StaFF (stabilisation of final focus) system will use interferometers to monitor the relative ... quadrupole magnets will be the most demanding application, where mutual and beam- ... interferometers to measure lines of a geodetic network to record relative motion between two beam ... coupled interferometer design.

Spatiotemporal oscillatory dynamics of visual selective attention during a flanker task.

Science.gov (United States)

McDermott, Timothy J; Wiesman, Alex I; Proskovec, Amy L; Heinrichs-Graham, Elizabeth; Wilson, Tony W

2017-08-01

The flanker task is a test of visual selective attention that has been widely used to probe error monitoring, response conflict, and related constructs. However, to date, few studies have focused on the selective attention component of this task and imaged the underlying oscillatory dynamics serving task performance. In this study, 21 healthy adults successfully completed an arrow-based version of the Eriksen flanker task during magnetoencephalography (MEG). All MEG data were pre-processed and transformed into the time-frequency domain. Significant oscillatory brain responses were imaged using a beamforming approach, and voxel time series were extracted from the peak responses to identify the temporal dynamics. Across both congruent and incongruent flanker conditions, our results indicated robust decreases in alpha (9-12Hz) activity in medial and lateral occipital regions, bilateral parietal cortices, and cerebellar areas during task performance. In parallel, increases in theta (3-7Hz) oscillatory activity were detected in dorsal and ventral frontal regions, and the anterior cingulate. As per conditional effects, stronger alpha responses (i.e., greater desynchronization) were observed in parietal, occipital, and cerebellar cortices during incongruent relative to congruent trials, whereas the opposite pattern emerged for theta responses (i.e., synchronization) in the anterior cingulate, left dorsolateral prefrontal, and ventral prefrontal cortices. Interestingly, the peak latency of theta responses in these latter brain regions was significantly correlated with reaction time, and may partially explain the amplitude difference observed between congruent and incongruent trials. Lastly, whole-brain exploratory analyses implicated the frontal eye fields, right temporoparietal junction, and premotor cortices. These findings suggest that regions of both the dorsal and ventral attention networks contribute to visual selective attention processes during incongruent trials

Oscillatory brain correlates of live joint attention: a dual-EEG study

Directory of Open Access Journals (Sweden)

Fanny eLachat

2012-06-01

Full Text Available Joint attention consists in following another’s gaze onto an environmental object, which leads to the alignment of both subjects' attention onto this object. It is a fundamental mechanism of non-verbal communication, and it is essential for dynamic, online, interindividual synchronization during interactions. We aimed at investigating the oscillatory brain correlates of joint attention in a face-to-face paradigm where dyads of participants dynamically oriented their attention toward objects during joint and no-joint attention periods respectively. We also manipulated task instruction: in socially-driven instructions, the participants had to follow explicitly their partner’s gaze, while in color-driven instructions, the objects to be looked at were designated at by their color so that no explicit gaze following was required. We focused on oscillatory activities in the 10 Hz frequency range, where parieto-occipital alpha and the centro-parietal mu rhythms have been described, as these rhythms have been associated with attention and social coordination processes respectively. We tested the hypothesis of a modulation of these oscillatory activities by joint attention. We used dual EEG to record simultaneously the brain activities of the participant dyads during our live, face-to-face joint attention paradigm. We showed that joint attention periods – as compared to the no-joint attention periods – were associated with a decrease of signal power between 11 and 13 Hz over a large set of left centro-parieto-occipital electrodes, encompassing the scalp regions where alpha and mu rhythms have been described. This 11-13 Hz signal power decrease was observed independently of the task instruction: it was similar when joint versus no-joint attention situations were socially-driven and when they were color-driven. These results are interpreted in terms of the processes of attention mirroring, social coordination, and mutual attentiveness associated

Theoretical investigation of flute modes in a magnetic quadrupole

International Nuclear Information System (INIS)

Wu, H.S.

1988-01-01

This research developed theories and conducted numerical investigations of electrostatic flute modes in a plasma confined in a magnetic quadrupole. Chapter I presents the discussion of relevant background. Chapter II contains a brief discussion of the basic flute-mode operator L 0 for intermediate- and low-frequency regimes. Chapter III develops a simple theory for a flute mode with frequency between the electron and ion bounce frequencies in the uniform density and temperature regions of a magnetic quadrupole. The frequency is predicted to be inversely proportional to the wave number. Chapter IV describes the kinetic approach. Chapter V contains the derivation of an eigenvalue equation for electrostatic waves with frequencies below the ion frequency in the private flux region of a magnetic quadrupole. Chapter VI develops a theory for electrostatic waves with frequency below the ion bounce frequency in the shared flux region of a magnetic quadrupole. Chapter VII contains the derivation of a dispersion equation for flute modes with frequencies between the electron and ion bounce frequencies in a plasma confined to a magnetic quadrupole. Chapter VIII presents a summary of the research described

A 120 mm Bore Quadrupole for the Phase 1 LHC Upgrade

CERN Document Server

Fessia, P; Borgnolutti, F; Regis, F; Richter, D; Todesco, E

2010-01-01

The phase I LHC upgrade foresees the installation of a new final focusing for the high luminosity experiences in order to be able to focus the beams in the interaction points to b*~ 0.25 cm. Key element of this upgrade is a large bore (120 mm) superconducting quadrupole. This article proposes a magnet design that will make use of the LHC main dipole superconducting cable. Due to the schedule constraints and to the budget restrictions, it is mandatory to integrate in the design the maximum number of features successfully used during the LHC construction. This paper presents this design option and the rationales behind the several technical choices.

Design of an rf quadrupole for Landau damping

Science.gov (United States)

Papke, K.; Grudiev, A.

2017-08-01

The recently proposed superconducting quadrupole resonator for Landau damping in accelerators is subjected to a detailed design study. The optimization process of two different cavity types is presented following the requirements of the High Luminosity Large Hadron Collider (HL-LHC) with the main focus on quadrupolar strength, surface peak fields, and impedance. The lower order and higher order mode (LOM and HOM) spectrum of the optimized cavities is investigated and different approaches for their damping are proposed. On the basis of an example the first two higher order multipole errors are calculated. Likewise on this example the required rf power and optimal external quality factor for the input coupler is derived.

Radiation Load Optimization in the Final Focus System of FCC-hh

CERN Document Server

Martin, Roman; Cerutti, Francesco; Tomás, Rogelio

2016-01-01

With a center-of-mass energy of up to 100 TeV, FCC-hh will produce highly energetic collision debris at the Interaction Point (IP). Protecting the final focus quadrupoles from this radiation is challenging, since the required amount of shielding placed inside the magnets will reduce the free aperture, thereby limiting the β^{*} reach and luminosity. Hence, radiation mitigation strategies that make best use of the available aperture are required. In this paper, we study the possibility to split the first quadrupole Q1 into two quadrupoles with individual apertures, in order to distribute the radiation load more evenly and reduce the peak dose.

Collisional damping of giant monopole and quadrupole resonances

International Nuclear Information System (INIS)

Yildirim, S.; Gokalp, A.; Yilmaz, O.; Ayik, S.

2001-01-01

Collisional damping widths of giant monopole and quadrupole excitations for 120 Sn and 208 Pb at zero and finite temperatures are calculated within Thomas-Fermi approximation by employing the microscopic in-medium cross-sections of Li and Machleidt and the phenomenological Skyrme and Gogny forces, and are compared with each other. The results for the collisional widths of giant monopole and quadrupole vibrations at zero temperature as a function of the mass number show that the collisional damping of giant monopole vibrations accounts for about 30 - 40% of the observed widths at zero temperature, while for giant quadrupole vibrations it accounts for only 20 - 30% of the observed widths at zero temperature. (orig.)

Table of Nuclear Electric Quadrupole Moments

International Nuclear Information System (INIS)

Stone, N.J.

2013-12-01

This Table is a compilation of experimental measurements of static electric quadrupole moments of ground states and excited states of atomic nuclei throughout the periodic table. To aid identification of the states, their excitation energy, half-life, spin and parity are given, along with a brief indication of the method and any reference standard used in the particular measurement. Experimental data from all quadrupole moment measurements actually provide a value of the product of the moment and the electric field gradient [EFG] acting at the nucleus. Knowledge of the EFG is thus necessary to extract the quadrupole moment. A single recommended value of the moment is given for each state, based, for each element, wherever possible, upon a standard reference moment for a nuclear state of that element studied in a situation in which the electric field gradient has been well calculated. For several elements one or more subsidiary reference EFG/moment references are required and their use is specified. The literature search covers the period to mid-2013. (author)

Fifth-order aberrations in magnetic quadrupole-octupole systems

International Nuclear Information System (INIS)

Ling, K.M.

1990-01-01

Explicit integral expressions are given for the fifth-order geometrical aberration coefficients in rectilinear magnetic quadrupole-octupole systems used for the transport of nonrelativistic charged particle beams. The numerical values of the fifth-order geometrical aberration coefficients for a rare earth cobalt (REC) quadrupole doublet are given as an example. 26 refs., 5 figs., 4 tabs

Experimental study of the turbulent boundary layer in acceleration-skewed oscillatory flow

NARCIS (Netherlands)

van der A, D.A.; O' Donoghue, T.; Davies, A.G; Ribberink, Jan S.

2011-01-01

Experiments have been conducted in a large oscillatory flow tunnel to investigate the effects of acceleration skewness on oscillatory boundary layer flow over fixed beds. As well as enabling experimental investigation of the effects of acceleration skewness, the new experiments add substantially to

Analytical study of envelope modes for a fully depressed beam in solenoidal and quadrupole periodic transport channels

International Nuclear Information System (INIS)

Bukh, Boris; Lund, Steven M.

2003-01-01

We present an analysis of envelope perturbations evolving in the limit of a fully space-charge depressed (zero emittance) beam in periodic, thin-lens focusing channels. Both periodic solenoidal and FODO quadrupole focusing channels are analyzed. The phase advance and growth rate of normal mode perturbations are analytically calculated as a function of the undepressed particle phase advance to characterize the evolution of envelope perturbations

Progress in the development of superconducting quadrupoles for heavy ion fusion

International Nuclear Information System (INIS)

Faltens, A.; Lietzke, A.; Sabbi, G.; Seidl, P.; Lund, S.; Manahan, B.; Martovetsky, N.; Gung, C.; Minervini, J.; Schultz, J.; Myatt, L.; Meinke, R.

2002-01-01

The Heavy Ion Fusion program is developing single aperture superconducting quadrupoles based on NbTi conductor, for use in the High Current Experiment at Lawrence Berkeley National Laboratory. Following the fabrication and testing of prototypes using two different approaches, a baseline design has been selected and further optimized. A prototype cryostat for a quadrupole doublet, with features to accommodate induction acceleration modules, is being fabricated. The single aperture magnet was derived from a conceptual design of a quadrupole array magnet for multi-beam transport. Progress on the development of superconducting quadrupole arrays for future experiments is also reported

Progress in the development of superconducting quadrupoles for heavy ion fusion

Energy Technology Data Exchange (ETDEWEB)

Faltens, A.; Lietzke, A.; Sabbi, G.; Seidl, P.; Lund, S.; Manahan, B.; Martovetsky, N.; Gung, C.; Minervini, J.; Schultz, J.; Myatt, L.; Meinke, R.

2002-05-24

The Heavy Ion Fusion program is developing single aperture superconducting quadrupoles based on NbTi conductor, for use in the High Current Experiment at Lawrence Berkeley National Laboratory. Following the fabrication and testing of prototypes using two different approaches, a baseline design has been selected and further optimized. A prototype cryostat for a quadrupole doublet, with features to accommodate induction acceleration modules, is being fabricated. The single aperture magnet was derived from a conceptual design of a quadrupole array magnet for multi-beam transport. Progress on the development of superconducting quadrupole arrays for future experiments is also reported.

Progress in the Development of Superconducting Quadrupoles forHeavy-ion Fusion

Energy Technology Data Exchange (ETDEWEB)

Faltens, A.; Lietzke, A.; Sabbi, G.; Seidl, P.; Lund, S.; Manahan, R.; Martovetsky, N.; Gung, C.; Minervini, J.; Schultz, J.; Myatt, L.; Meinke, R.

2002-08-19

The Heavy Ion Fusion program is developing single aperture superconducting quadrupoles based on NbTi conductor, for use in the High Current Experiment at Lawrence Berkeley National Laboratory. Following the fabrication and testing of prototypes using two different approaches, a baseline design has been selected and further optimized. A prototype cryostat for a quadrupole doublet, with features to accommodate induction acceleration modules, is being fabricated. The single aperture magnet was derived from a conceptual design of a quadrupole array magnet for multi-beam transport. Progress on the development of superconducting quadrupole arrays for future experiments is also reported.

Field quality of the LHC inner triplet quadrupoles being fabricated at Fermilab

Energy Technology Data Exchange (ETDEWEB)

Gueorgui V. Velev et al.

2003-06-02

Fermilab, as part of the US-LHC Accelerator Project, has designed and is producing superconducting low-beta quadrupole magnets for the Large Hadron Collider (LHC). These 70 mm bore, 5.5 m long magnets operate in superfluid helium at 1.9 K with a maximum operating gradient of 214 T/m. Two quadrupoles, combined with a dipole orbit corrector, form a single LQXB cryogenic assembly, the Q2 optical element of the final focus triplets in the LHC interaction regions. Field quality was measured at room temperature during fabrication of the cold masses as well as at superfluid helium temperature in two thermal cycles for the first LQXB cryogenic assembly. Integral cold measurements were made with a 7.1 m long rotating coil and with a 0.8 m long rotating coil at 8 axial positions and in a range of currents. In addition to the magnetic measurements, this paper reports on the quench performance of the cold masses and on the measurements of their internal alignment.

A sensitiviy analysis for the stabilization of the CLIC main beam quadrupoles

CERN Document Server

Janssens, S; Artoos, K; Fernandez Carmona, P; Hauviller, C

2010-01-01

In particle colliders (like the LHC), particles are highly accelerated in a circular beam pipe before the collision. However, due to the curved trajectory of the particles, they are also loosing energy because of the so-called Bremsstrahlung. In order to bypass this fundamental limitation imposed by circular beams, the next generation of particle colliders will accelerate two straight beams of particles before the collision. One of them, the Compact Linear Collider, is currently under study at CERN. The machine is constituted of a huge number of accelerating structures (used to accelerate the particles) and quadrupoles (electromagnets used to focus the particles). The latter ones are required to be stable at the nanometer level. This extreme stability has to be guaranteed by active vibration isolation from all types of disturbances like ground vibrations, ventilation, cooling system, or acoustic noise. Because of the huge number of quadrupoles (about 4000), it is critical that the strategy adopted for the act...

ISR "Terwilliger" Quadrupole

CERN Multimedia

1983-01-01

There were 48 of these Quadrupoles in the ISR. They were distributed around the rings according to the so-called Terwilliger scheme. Their aperture was 184 mm, their core length 300 mm, their gradient 5 T/m. Due to their small length as compared to the aperture, the end fringe field errors had to be compensated by suitably shaping the poles.

Global study of quadrupole correlation effects

International Nuclear Information System (INIS)

Bender, M.; Bertsch, G.F.; Heenen, P.-H.

2006-01-01

We discuss the systematics of ground-state quadrupole correlations of binding energies and mean-square charge radii for all even-even nuclei, from 16 O up to the superheavies, for which data are available. To that aim we calculate their correlated J=0 ground state by means of the angular-momentum and particle-number projected generator coordinate method, using the axial mass quadrupole moment as the generator coordinate and self-consistent mean-field states restricted only by axial, parity, and time-reversal symmetries. The calculation is performed within the framework of a nonrelativistic self-consistent mean-field model by use of the same Skyrme interaction SLy4 and to a density-dependent pairing force to generate the mean-field configurations and to mix them. These are the main conclusions of our study: (i) The quadrupole correlation energy varies between a few 100 keV and about 5.5 MeV. It is affected by shell closures, but varies only slightly with mass and asymmetry. (ii) Projection on angular momentum J=0 provides the major part of the energy gain of up to about 4 MeV; all nuclei in the study, including doubly magic ones, gain energy by deformation. (iii) The mixing of projected states with different intrinsic axial deformations adds a few 100 keV up to 1.5 MeV to the correlation energy. (iv) Typically nuclei below mass A≤60 have a larger correlation energy than static deformation energy whereas the heavier deformed nuclei have larger static deformation energy than correlation energy. (v) Inclusion of the quadrupole correlation energy improves the description of mass systematics, particularly around shell closures, and of differential quantities, namely two-nucleon separation energies and two-nucleon gaps. The correlation energy provides an explanation of 'mutually enhanced magicity'. (vi) The correlation energy tends to decrease the shell effect on binding energies around magic numbers, but the magnitude of the suppression is not large enough to explain

Fe/sup 57/ polarimetry based on quadrupole interaction

Energy Technology Data Exchange (ETDEWEB)

Gonser, U; Sakai, H; Keune, W [Universitaet des Saarlandes, Saarbruecken (F.R. Germany). Fachbereich Angewandte Physik

1976-01-01

A quadrupole Fe/sup 57/ polarimeter consisting of single crystals of LiNbO/sub 3/:Co/sup 57/ as source (polarizer) and of FeCO/sub 3/ (siderite) as absorber (analyzer) is described. The quadrupole interactions of the two materials are nearly equal in magnitude but opposite in sign and in addition the asymmetry parameter eta equal approximately 0.

An extended discrete gradient formula for oscillatory Hamiltonian systems

International Nuclear Information System (INIS)

Liu Kai; Shi Wei; Wu Xinyuan

2013-01-01

In this paper, incorporating the idea of the discrete gradient method into the extended Runge–Kutta–Nyström integrator, we derive and analyze an extended discrete gradient formula for the oscillatory Hamiltonian system with the Hamiltonian H(p,q)= 1/2 p T p+ 1/2 q T Mq+U(q), where q:R→R d represents generalized positions, p:R→R d represents generalized momenta and M is an element of R dxd is a symmetric and positive semi-definite matrix. The solution of this system is a nonlinear oscillator. Basically, many nonlinear oscillatory mechanical systems with a partitioned Hamiltonian function lend themselves to this approach. The extended discrete gradient formula presented in this paper exactly preserves the energy H(p, q). We derive some properties of the new formula. The convergence is analyzed for the implicit schemes based on the discrete gradient formula, and it turns out that the convergence of the implicit schemes based on the extended discrete gradient formula is independent of ‖M‖, which is a significant property for the oscillatory Hamiltonian system. Thus, it transpires that a larger step size can be chosen for the new energy-preserving schemes than that for the traditional discrete gradient methods when applied to the oscillatory Hamiltonian system. Illustrative examples show the competence and efficiency of the new schemes in comparison with the traditional discrete gradient methods in the scientific literature. (paper)

Multi-elemental analysis of aqueous geochemical samples by quadrupole inductively coupled plasma-mass spectrometry (ICP-MS)

Science.gov (United States)

Wolf, Ruth E.; Adams, Monique

2015-01-01

Typically, quadrupole inductively coupled plasma-mass spectrometry (ICP-MS) is used to determine as many as 57 major, minor, and trace elements in aqueous geochemical samples, including natural surface water and groundwater, acid mine drainage water, and extracts or leachates from geological samples. The sample solution is aspirated into the inductively coupled plasma (ICP) which is an electrodeless discharge of ionized argon gas at a temperature of approximately 6,000 degrees Celsius. The elements in the sample solution are subsequently volatilized, atomized, and ionized by the ICP. The ions generated are then focused and introduced into a quadrupole mass filter which only allows one mass to reach the detector at a given moment in time. As the settings of the mass analyzer change, subsequent masses are allowed to impact the detector. Although the typical quadrupole ICP-MS system is a sequential scanning instrument (determining each mass separately), the scan speed of modern instruments is on the order of several thousand masses per second. Consequently, typical total sample analysis times of 2–3 minutes are readily achievable for up to 57 elements.

Enhanced Gamma Oscillatory Activity in Rats with Chronic Inflammatory Pain

OpenAIRE

Wang, Jing; Wang, Jing; Xing, Guo-Gang; Li, Xiaoli; Wan, You

2016-01-01

It has been reported that oscillatory gamma activity participates in brief acute pain and tonic ongoing pain. It is of great interest to determine whether the gamma activity is involved in chronic pain since chronic pain is a more severe pathological condition characterized by pain persistency. To investigate the oscillatory gamma activity in chronic pain, in the present study, we recorded spontaneous electrocorticogram (ECoG) signals during chronic pain development in rats with chronic infla...

Static quadrupole moment of the Kπ = 14+ isomer in 176W

International Nuclear Information System (INIS)

Ionescu-Bujor, M.; Iordachescu, A.; Bucurescu, D.; Brandolini, F.; Lenzi, S. M.; Pavan, P.; Rossi Alvarez, C.; Marginean, N.; Medina, N.H.; Ribas, R.V.; De Poli, M.; Napoli, D. R.; Podolyak, Zs.; Ur, C. A.

2001-01-01

The investigation of high-K isomeric states in the deformed nuclei of the A∼180 region has found renewed interest in recent years. Much experimental and theoretical work was devoted to understand the mechanisms which govern their decay to lower-lying states, particularly the anomalous strong decays to low-K states. Other questions of great importance are the quenching of the pairing correlations and the shape polarization effects in the high-seniority multi-quasiparticle excitations. Our interest focused on the 41 ns K π =14 + 3746 keV isomeric state with anomalous decay in 176 W. On the basis of a precise g-factor measurement we assigned to this isomer a pure four-quasiparticle configuration, composed by two protons in the 7/2 + [404] and 9/2 - [514] orbitals and two neutrons in the 7/2 + [633] and 5/2 - [512] orbitals. In the present work the measurement of its static quadrupole moment has been performed. Prior to our experiment, static quadrupole moments have been measured only for three high-K isomeric states of seniority ≥ 4 in the A∼180 region: 16 + in 178 Hf, 35/2 - in 179 W and 25 + in 182 Os. A deformation very similar to that of the ground state has been deduced for the 16 + isomer in 178 Hf, while for the high-K isomers in 179 W and 182 Os significantly smaller deformations were reported. The quadrupole interaction of the 14 + isomeric state in 176 W has been investigated in the electric field gradient (EFG) of the polycrystalline lattice of metallic Tl by applying the time-differential perturbed angular distribution method. For W impurities in Tl host the EFG strength and its temperature dependence have been recently reported. The isomer was populated in the 164 Dy( 16 O,4n) 176 W reaction using a 83 MeV 16 O pulsed beam (pulse width 1.5 ns, repetition period 800 ns) delivered by the XTU-Tandem of Laboratori Nazionali di Legnaro. The target consisted of 0.5 mg/cm 2 metallic 164 Dy on thick Tl backing in which both the recoiling 176 W nuclei and

Learning in AN Oscillatory Cortical Model

Science.gov (United States)

Scarpetta, Silvia; Li, Zhaoping; Hertz, John

We study a model of generalized-Hebbian learning in asymmetric oscillatory neural networks modeling cortical areas such as hippocampus and olfactory cortex. The learning rule is based on the synaptic plasticity observed experimentally, in particular long-term potentiation and long-term depression of the synaptic efficacies depending on the relative timing of the pre- and postsynaptic activities during learning. The learned memory or representational states can be encoded by both the amplitude and the phase patterns of the oscillating neural populations, enabling more efficient and robust information coding than in conventional models of associative memory or input representation. Depending on the class of nonlinearity of the activation function, the model can function as an associative memory for oscillatory patterns (nonlinearity of class II) or can generalize from or interpolate between the learned states, appropriate for the function of input representation (nonlinearity of class I). In the former case, simulations of the model exhibits a first order transition between the "disordered state" and the "ordered" memory state.

Oscillatory processes in plasma

International Nuclear Information System (INIS)

Gallin, E.

1980-01-01

The oscillatory process play an important part in plasma evolution, In hot plasma in particular, the interactions between the oscillation modes are preponderant in relation to the binary collisions between particles. The nonlineary interactions between collective plasma oscillations can generate, in this case, a non-balanced steady state of plasma (steady turbulence). The paper elucidates some aspects of the oscillatory phenomena which contribute to the plasma state evolution, especially of hot plasma. A major part of the paper is devoted to the study of parametric instabilities in plasma and their role in increasing the temperature of plasma components (electrons, ions). Both parametric instabilities in plasma in the vicinity of thermodynamic balance and parametric processes is steady turbulent plasma are analysed - in relation to additional heating of hot plasma. An important result of the thesis refers to the drowing-up of a non-lineary interaction model between the oscillation modes in turbulent plasma, being responsible for the electromagnetic radiation in hot plasma. On the basis of the model suggested in the paper the existence of a low frequency radiative mode in hot plasma in a turbulent state, can be demonstrated. Its frequency could be even lower than plasma frequency in the field of long waves be even lower than plasma frequency in the field of long waves. Such a radiative mode was detected experimentally in focussed plasma installations. (author)

Semimicroscopic description of the giant quadrupole resonances in deformed nuclei

International Nuclear Information System (INIS)

Kurchev, G.; Malov, L.A.; Nesterenko, V.O.; Soloviev, V.G.

1976-01-01

The calculation results of the giant quadrupole isoscalar and isovector resonances performed within the random phase approximation are represented. The strength functions for E2-transitions are calculated for doubly even deformed nuclei in the regions 150 (<=) A < 190 and 228 (<=) A < 248 in the energy interval (0-40) MeV. The following integral characteristics of giant quadrupole resonances are obtained: the position, widths, the contribution to the energy weighted sum rule and the contribution to the total cross section of photoabsorption. The calculations have shown that giant quadrupole resonances are common for all the considered nuclei. The calculated characteristics of the isoscalar giant quadrupole resonance agree with the available experimental data. The calculations also show that the semimicroscopic theory can be successfully applied for the description of giant multipole resonances

Kinetic energy in the collective quadrupole Hamiltonian from the experimental data

Energy Technology Data Exchange (ETDEWEB)

Jolos, R.V., E-mail: jolos@theor.jinr.ru [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Dubna State University, 141980 Dubna (Russian Federation); Kolganova, E.A. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Dubna State University, 141980 Dubna (Russian Federation)

2017-06-10

Dependence of the kinetic energy term of the collective nuclear Hamiltonian on collective momentum is considered. It is shown that the fourth order in collective momentum term of the collective quadrupole Hamiltonian generates a sizable effect on the excitation energies and the matrix elements of the quadrupole moment operator. It is demonstrated that the results of calculation are sensitive to the values of some matrix elements of the quadrupole moment. It stresses the importance for a concrete nucleus to have the experimental data for the reduced matrix elements of the quadrupole moment operator taken between all low lying states with the angular momenta not exceeding 4.

Tests of planar permanent magnet multipole focusing elements

International Nuclear Information System (INIS)

Cobb, J.; Tatchyn, R.

1993-08-01

In recent work, planar configurations of permanent magnets were proposed as substitutes for conventional current-driven iron quadrupoles in applications limited by small aperture sizes and featuring small beam occupation diameters. Important examples include the configuring of focusing lattices in small-gap insertion devices, and the implementation of compact mini-beta sections on linear or circular machines. In subsequent analysis, this approach was extended to sextupoles and higher-order multipoles. In this paper we report on initial measurements conducted at the Stanford Linear Accelerator Center on recently fabricated planar permanent magnet quadrupoles and sextupoles configured out of SmCo and NdFe/B

Separation of transient and oscillatory cerebral activities using over-complete rational dilation wavelet transforms

International Nuclear Information System (INIS)

Chaibi, S.; Lajnef, T.; Samet, M.; Kachouri, A.

2011-01-01

Many natural signals EEG are comprised frequency overlapping of oscillatory and transient components. In our study the intracranial EEG signals of epilepsy are composed of the superposition of oscillatory signals (HFOs: High Frequency oscillations) and a transient signals (spikes and sharp waves, etc.). The oscillatory components (HFOs) exist in the frequency band 80-500Hz. The transient components comes from nonrhythmic brain activities (spikes, sharp waves and vertex waves of varying amplitude, shape and duration) and cover a continuous wide bandwidth from low to high frequencies and resemble an HFOs events when filtered using a band pass classical filter. The classical filtering methods based on FIR filters, Wavelet transforms and the Matching Pursuit cannot separate the oscillatory from transient activities. This paper describes an approach for decomposing an iEEG signals of epilepsy into the sum of oscillatory components and a transient components based on overcomplete rational dilation wavelet transforms (overcomplete RADWT) in conjunction with morphological component analysis (MCA).

Implementation of $ab$ $initio$ perturbed angular correlation observables for analysis of fluctuating quadrupole interactions

CERN Document Server

Barbosa, Marcelo

A review about the nuclear properties, namely the nuclear moments (magnetic dipole moment and electric quadrupole moment) and their interaction with electromagnetic fields external to the nucleus (hyperfine interactions), as well as the angular distribution of radiation produced by $\\gamma$-decay, is presented. A detailed description about the theory of Perturbed Angular Correlations was done, including the comparison between $\\gamma-\\gamma$- correlations and $e^{-}- \\gamma$ correlations. For dynamic nuclear interactions, an introduction to the theory of stochastic states in PAC was performed. We focused on ab-initio implementation of observables for analyzing fluctuating quadrupole hyperfine interactions on time dependent perturbed angular correlations experiments. The development of computacional codes solving the full problem, adapted to fit data obtained on single crystals or polycrystals for two-state transient fields with any axial symmetry and orientation was the main purpose of this work. The final pa...

Quadrupole moments as measures of electron correlation in two-electron atoms

International Nuclear Information System (INIS)

Ceraulo, S.C.; Berry, R.S.

1991-01-01

We have calculated quadrupole moments, Q zz , of helium in several of its doubly excited states and in two of its singly excited Rydberg states, and of the alkaline-earth atoms Be, Mg, Ca, Sr, and Ba in their ground and low-lying excited states. The calculations use well-converged, frozen-core configuration-interaction (CI) wave functions and, for interpretive purposes, Hartree-Fock (HF) atomic wave functions and single-term, optimized, molecular rotor-vibrator (RV) wave functions. The quadrupole moments calculated using RV wave functions serve as a test of the validity of the correlated, moleculelike model, which has been used to describe the effects of electron correlation in these two-electron and pseudo-two-electron atoms. Likewise, the quadrupole moments calculated with HF wave functions test the validity of the independent-particle model. In addition to their predictive use and their application to testing simple models, the quadrupole moments calculated with CI wave functions reveal previously unavailable information about the electronic structure of these atoms. Experimental methods by which these quadrupole moments might be measured are also discussed. The quadrupole moments computed from CI wave functions are presented as predictions; measurements of Q zz have been made for only two singly excited Rydberg states of He, and a value of Q zz has been computed previously for only one of the states reported here. We present these results in the hope of stimulating others to measure some of these quadrupole moments

Design of an rf quadrupole for Landau damping

Directory of Open Access Journals (Sweden)

K. Papke

2017-08-01

Full Text Available The recently proposed superconducting quadrupole resonator for Landau damping in accelerators is subjected to a detailed design study. The optimization process of two different cavity types is presented following the requirements of the High Luminosity Large Hadron Collider (HL-LHC with the main focus on quadrupolar strength, surface peak fields, and impedance. The lower order and higher order mode (LOM and HOM spectrum of the optimized cavities is investigated and different approaches for their damping are proposed. On the basis of an example the first two higher order multipole errors are calculated. Likewise on this example the required rf power and optimal external quality factor for the input coupler is derived.

Rf quadrupole beam dynamics

International Nuclear Information System (INIS)

Stokes, R.H.; Crandall, K.R.; Stovall, J.E.; Swenson, D.A.

1979-01-01

A method has been developed to analyze the beam dynamics of the radiofrequency quadrupole accelerating structure. Calculations show that this structure can accept a dc beam at low velocity, bunch it with high capture efficiency, and accelerate it to a velocity suitable for injection into a drift tube linac

Bray–Liebhafsky oscillatory reaction in the radiofrequency electromagnetic field

Energy Technology Data Exchange (ETDEWEB)

Stanisavljev, Dragomir R., E-mail: dragisa@ffh.bg.ac.rs [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, P.O. Box 473, 11001 Belgrade (Serbia); Velikić, Zoran [Institute of Physics, University of Belgrade, Pregrevica 118, Zemun (Serbia); Veselinović, Dragan S.; Jacić, Nevena V.; Milenković, Maja C. [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, P.O. Box 473, 11001 Belgrade (Serbia)

2014-09-30

Highlights: • Oscillatory Bray–Liebhafsky reaction is coupled with the radiofrequency radiation. • The effects of radiofrequency field on oscillatory parameters are investigated. • Radiofrequency power of up to the 0.2 W did not produced observable changes. • The explanation related with dissipative and capacitive effects is given. • Open the possibility of investigations of reactive effects on biological systems. - Abstract: Oscillatory Bray–Liebhafsky (BL) reaction is capacitively coupled with the electromagnetic radiation in the frequency range 60–110 MHz. Because of the specific reaction dynamics characterized by several characteristic parameters (induction period, period between chemical oscillations and their amplitude) it served as a good model system for the investigation of the effects of radiofrequent (RF) radiation. RF power of up to 0.2 W did not produce observable changes of the BL reaction parameters in the limit of the experiment reproductivity. Results indicate that, under the given experimental conditions, both dissipative and reactive properties of the solution are not considerably coupled with the RF electrical field.

The Nonlinear Distortions in the Oscillatory System of Generator on CFOA

Directory of Open Access Journals (Sweden)

Yuriy Konstantinovich Rybin

2012-01-01

Full Text Available In recent years, many articles came out where one could find the analysis of oscillatory systems of electric sinusoid signals generators with amplifiers called CFOA—current feedback operational amplifiers. As a rule, the analysis of such systems is made by applying mathematical modeling methods on the basis of the amplifier linear model, which does not allow estimating advantages and disadvantages of the systems realized with those amplifiers in comparison with classical systems. A nonlinear model of a current feedback operational amplifier (CFOA is introduced in the paper; nonlinearity of “current mirror” is reflected in the form of current double limiting. The analysis of two known oscillatory systems has been carried out with the use of this non-linear model. Dependence between current limiting level, output voltage amplitude, and maximum oscillation frequency has been obtained. The paper shows that output current limiting under current output connection of capacitive load reduces frequency range and output voltage amplitude considerably and increases harmonic distortions in comparison with classical oscillatory systems. The research done has found that the application of new amplifiers does not give considerable advantages to the oscillatory systems with CFOA.

Oscillatory wake potential with exchange-correlation in plasmas

Science.gov (United States)

Khan, Arroj A.; Zeba, I.; Jamil, M.; Asif, M.

2017-12-01

The oscillatory wake potential of a moving test charge is studied in quantum dusty plasmas. The plasma system consisting of electrons, ions and negatively charged dust species is embedded in an ambient magnetic field. The modified equation of dispersion is derived using a Quantum Hydrodynamic Model for magnetized plasmas. The quantum effects are inculcated through Fermi degenerate pressure, the tunneling effect and exchange-correlation effects. The study of oscillatory wake is important to know the existence of silence zones in space and astrophysical objects as well as for crystal formation. The graphical description of the potential depicts the significance of the exchange and correlation effects arising through spin and other variables on the wake potential.

A high gradient superconducting quadrupole for a low charge state ion linac

International Nuclear Information System (INIS)

Kim, J.W.; Shepard, K.W.; Nolen, J.A.

1995-01-01

A superconducting quadrupole magnet has been designed for use as the focusing element in a low charge state linac proposed at Argonne. The expected field gradient is 350 T/m at an operating current of 53 A, and the bore diameter is 3 cm. The use of rare earth material holmium for pole tips provides about 10% more gradient then iron pole tips. The design and the status of construction of a prototype singlet magnet is described

Changes of spontaneous oscillatory activity to tonic heat pain.

Science.gov (United States)

Peng, Weiwei; Hu, Li; Zhang, Zhiguo; Hu, Yong

2014-01-01

Transient painful stimuli could induce suppression of alpha oscillatory activities and enhancement of gamma oscillatory activities that also could be greatly modulated by attention. Here, we attempted to characterize changes in cortical activities during tonic heat pain perception and investigated the influence of directed/distracted attention on these responses. We collected 5-minute long continuous Electroencephalography (EEG) data from 38 healthy volunteers during four conditions presented in a counterbalanced order: (A) resting condition; (B) innoxious-distracted condition; (C) noxious-distracted condition; (D) noxious-attended condition. The effects of tonic heat pain stimulation and selective attention on oscillatory activities were investigated by comparing the EEG power spectra among the four experimental conditions and assessing the relationship between spectral power difference and subjective pain intensity. The change of oscillatory activities in condition D was characterized by stable and persistent decrease of alpha oscillation power over contralateral-central electrodes and widespread increase of gamma oscillation power, which were even significantly correlated with subjective pain intensity. Since EEG responses in the alpha and gamma frequency band were affected by attention in different manners, they are likely related to different aspects of the multidimensional sensory experience of pain. The observed contralateral-central alpha suppression (conditions D vs. B and D vs. C) may reflect primarily a top-down cognitive process such as attention, while the widespread gamma enhancement (conditions D vs. A) may partly reflect tonic pain processing, representing the summary effects of bottom-up stimulus-related and top-down subject-driven cognitive processes.

Changes of spontaneous oscillatory activity to tonic heat pain.

Directory of Open Access Journals (Sweden)

Weiwei Peng

Full Text Available Transient painful stimuli could induce suppression of alpha oscillatory activities and enhancement of gamma oscillatory activities that also could be greatly modulated by attention. Here, we attempted to characterize changes in cortical activities during tonic heat pain perception and investigated the influence of directed/distracted attention on these responses. We collected 5-minute long continuous Electroencephalography (EEG data from 38 healthy volunteers during four conditions presented in a counterbalanced order: (A resting condition; (B innoxious-distracted condition; (C noxious-distracted condition; (D noxious-attended condition. The effects of tonic heat pain stimulation and selective attention on oscillatory activities were investigated by comparing the EEG power spectra among the four experimental conditions and assessing the relationship between spectral power difference and subjective pain intensity. The change of oscillatory activities in condition D was characterized by stable and persistent decrease of alpha oscillation power over contralateral-central electrodes and widespread increase of gamma oscillation power, which were even significantly correlated with subjective pain intensity. Since EEG responses in the alpha and gamma frequency band were affected by attention in different manners, they are likely related to different aspects of the multidimensional sensory experience of pain. The observed contralateral-central alpha suppression (conditions D vs. B and D vs. C may reflect primarily a top-down cognitive process such as attention, while the widespread gamma enhancement (conditions D vs. A may partly reflect tonic pain processing, representing the summary effects of bottom-up stimulus-related and top-down subject-driven cognitive processes.

Cerebral oscillatory activity during simulated driving using MEG

Directory of Open Access Journals (Sweden)

Kotoe eSakihara

2014-12-01

Full Text Available We aimed to examine cerebral oscillatory differences associated with psychological processes during simulated car driving. We recorded neuromagnetic signals in 14 healthy volunteers using magnetoencephalography (MEG during simulated driving. MEG data were analyzed using synthetic aperture magnetometry to detect the spatial distribution of cerebral oscillations. Group effects between subjects were analyzed statistically using a nonparametric permutation test. Oscillatory differences were calculated by comparison between passive viewing and active driving. Passive viewing was the baseline, and oscillatory differences during active driving showed an increase or decrease in comparison with a baseline. Power increase in the theta band was detected in the superior frontal gyrus (SFG during active driving. Power decreases in the alpha, beta, and low gamma bands were detected in the right inferior parietal lobe (IPL, left postcentral gyrus (PoCG, middle temporal gyrus (MTG, and posterior cingulate gyrus (PCiG during active driving. Power increase in the theta band in the SFG may play a role in attention. Power decrease in the right IPL may reflect selectively divided attention and visuospatial processing, whereas that in the left PoCG reflects sensorimotor activation related to driving manipulation. Power decreases in the MTG and PCiG may be associated with object recognition.

Superconducting Panofsky quadrupoles

International Nuclear Information System (INIS)

Harwood, L.H.

1981-01-01

A design for a rectangular aperture quadrupole magnet without pole-tips was introduced by Hand and Panofsky in 1959. This design was quite radical but simple to construct. Few magnets of this design were ever built because of the large power needed. With the advent of superconducting coils there has been a renewed interest in them. The mathematical basis, field characteristics, and present and future construction of these magnets are described

Quadrupole interactions in pionic and muonic tantalum and rhenium

International Nuclear Information System (INIS)

Konijn, J.; Doesburg, W. van; Ewan, G.T; Johansson, T.; Tibell, G.

1981-01-01

The hyperfine splitting of pionic and muonic X-rays in natural Re has been studied using the known ratio (accurate to 1.6 parts in 10 5 ) of the quadrupole moments of the two naturally occurring 185 Re and 187 Re isotopes. From the hyperfine splitting of the 5g → 4f and 4f → 3d pionic X-rays the effective quadrupole hyperfine constants were determined to be 187 A 2 sup(e)sup(f)sup(f) (4f) = 1.163 +- 0.010 keV and 187 A 2 sup(e)sup(f)sup(f) (3d) = 5.39 +- 0.63 keV, giving strong interaction quadrupole shifts epsilon 2 (4f) = 46 +- 10 eV and epsilon 2 (3d) = 1.3 +- 0.6 keV. The strong interaction monopole shifts epsilon 0 and widths GAMMA 0 of the 5g, 4f and 3d levels have also been measured. For the two higher orbits, standard optical-potential calculations fit the measured shifts and widths quite well. The observed deeper-lying 3d state, however, has shifts and widths that differ by a factor of 2 or more from the predictions. From the measured quadrupole hyperfine constants of the 4f level we calculate the spectroscopic quadrupole moments to be 187 Qsup(μ) = 2.09 +- 0.04 b, 187 Qsup(π) = 2.07 +- 0.02 b, 185 Qsup(μ) = 2.21 +- 0.04 b, and 185 Qsup(π) = 2.18 +- 0.02 b. In addition, muonic X-rays from 181 Ta were observed; using the same methods for determining the quadrupole moments as above, a value of 181 Qsup(μ) = 3.28 +- 0.06 b was obtained, in good agreement with earlier published data. (orig.)

Quadrupole photoionization of endohedral Xe-C60

International Nuclear Information System (INIS)

Govil, Karan; Deshmukh, P C

2009-01-01

The effect of an endohedral confinement on the quadrupole photoionization of atomic Xe is studied using the relativistic random phase approximation (RRPA). The atom's confinement is modelled by placing atomic Xe at the centre of a C 60 cage represented by an annular potential around it. A new confinement resonance is reported in the 4p quadrupole cross-section along with 'correlation confinement resonances' in 4d, 5s and 5p photoionizations at about 185 eV. The effect of the confinement on the non-dipole photoelectron angular distribution parameter γ is also reported.

High and ulta-high gradient quadrupole magnets

International Nuclear Information System (INIS)

Brunk, W.O.; Walz, D.R.

1985-05-01

Small bore conventional dc quadrupoles with apertures from 1 to 2.578cm were designed and prototypes built and measured. New fabrication techniques including the use of wire electric discharge milling (EDM) to economically generate the pole tip contours and aperture tolerances are described. Magnetic measurement data from a prototype of a 1cm aperture quadrupole with possible use in future e + /e - super colliders are presented. At a current of 400A, the lens achieved a gradient of 2.475 T/cm, and had an efficiency of 76.6%

Quadrupole formula for Kaluza-Klein modes in the braneworld

International Nuclear Information System (INIS)

Kinoshita, Shunichiro; Kudoh, Hideaki; Sendouda, Yuuiti; Sato, Katsuhiko

2005-01-01

The quadrupole formula in four-dimensional Einstein gravity is a useful tool to describe gravitational wave radiation. We derive the quadrupole formula for the Kaluza-Klein (KK) modes in the Randall-Sundrum braneworld model. The quadrupole formula provides a transparent representation of the exterior weak gravitational field induced by localized sources. We find that a general isolated dynamical source gives rise to the 1/r 2 correction to the leading 1/r gravitational field. We apply the formula to an evaluation of the effective energy carried by the KK modes from the viewpoint of an observer on the brane. Contrary to the ordinary gravitational waves (zero mode), the flux of the induced KK modes by the non-spherical part of the quadrupole moment vanishes at infinity and only the spherical part contributes to the flux. Since the effect of the KK modes appears in the linear order of the metric perturbations, the effective energy flux observed on the brane is not always positive, but can become negative depending on the motion of the localized sources

Sensitivity of (α,α') cross sections to excited-state quadrupole moments

International Nuclear Information System (INIS)

Baker, F.T.; Scott, A.; Ronningen, R.M.; Hamilton, J.H.; Kruse, T.H.; Suchannek, R.; Savin, W.

1977-01-01

Inelastic α particle scattering at 21 and 24 MeV has been used to estimate the electric quadrupole moment of the second 2 + state in 180 Hf. Sensitivity to the assumed quadrupole moment is due almost entirely to reorientation via the nuclear force. Results suggest that the technique may be a useful method of estimating excited state quadrupole moments, particularly for states with high excitation energies or with J greater than 2

Large permanent magnet quadrupoles for an electron storage ring

International Nuclear Information System (INIS)

Herb, S.W.

1987-01-01

We have built large high quality permanent magnet quadrupoles for use as interaction region quadrupoles in the Cornell Electron Storage Ring where they must operate in the 10 kG axial field of the CLEO experimental detector. We describe the construction and the magnetic measurement and tuning procedures used to achieve the required field quality and stability. (orig.)

Skyrme's interaction beyond the mean-field. The DGCM+GOA Hamiltonian of nuclear quadrupole motion

Energy Technology Data Exchange (ETDEWEB)

Kluepfel, Peter

2008-07-29

This work focuses on the microscopic description of nuclear collective quadrupole motion within the framework of the dynamic Generator-Coordinate-Method(DGCM)+Gaussian-Overlap-Approximation(GOA). Skyrme-type effective interactions are used as the fundamental many-particle interaction. Starting from a rotational invariant, polynomial and topologic consistent formulation of the GCM+GOA Hamiltonian an interpolation scheme for the collective masses and potential is developed. It allows to define the collective Hamiltonian of fully triaxial collective quadrupole dynamics from a purely axial symmetric configuration space. The substantial gain in performance allows the self-consistent evaluation of the dynamic quadrupole mass within the ATDHF-cranking model. This work presents the first large-scale analysis of quadrupole correlation energies and lowlying collective states within the DGCM+GOA model. Different Skyrme- and pairing interactions are compared from old standards up to more recent parameterizations. After checking the validity of several approximations to the DGCM+GOA model - both on the mean-field and the collective level - we proceed with a detailed investigation of correlation effects along the chains of semi-magic isotopes and isotones. This finally allows to define a set of observables which are hardly affected by collective correlations. Those observables were used for a refit of a Skyrme-type effective interaction which is expected to cure most of the problems of the recent parameterizations. Preparing further work, estimates for the correlated ground state energy are proposed which can be evaluated directly from the mean-field model. (orig.)

Synthesis of focusing-and-deflection columns

International Nuclear Information System (INIS)

Szilagyi, M.; Mui, P.H.

1995-01-01

Szilagyi and Szep have demonstrated that focusing lenses of high performances can be constructed from a column of circular plate electrodes. Later, Szilagyi modified that system to include dipole, quadrupole, and octupole components by partitioning each plate into eight equal sectors. It has already been shown that the additional quadrupole components can indeed bring about substantial improvements in the focusing of charged particle beams. In this article, that design procedure is expanded to construct columns capable of both focusing and deflecting particle beams by just introducing additional dipole components. In this new design, the geometry of the system remains unchanged. The only extra complication is the demand for more individual controls of the sector voltages. Two sample designs, one for negative ions and one for electrons, are presented showing that in both cases a ±2.3 mrad diverging beam can be focused down to a spot of less than 50 nm in radius over a scanning circular area of radius 0.25 mm. The details of the two systems are given in Sec. IV along with the source conditions. The performance of the negative ion system is found to be comparable to the published data. For the relativistic electron system, the interaction of individual components to reduce various aberrations is investigated. copyright 1995 American Vacuum Society

Design of the 70 mm twin aperture superconducting quadrupole for the LHC dump insertion

CERN Document Server

Kirby, G A; Taylor, T M; Trinquart, G

1996-01-01

The LHC dump insertion features a pair of superconducting quadrupoles located on either side of a 340 m long straight section. Two horizontally deflecting kickers, located in between the quadrupole pairs, and a septum in the centre of the insertion, vertically deflect the two counter-rotating beams past the quadrupoles on the downstream sides, and into the dump areas. Due to the layout, the optical ß function in the quadrupoles is around 640 m, the largest around the LHC at injection. The quadrupoles must therefore have enlarged aperture and specially designed cryostats to allow for the safe passage of both the circulating and ejected beams. In this paper we present the design of the twin aperture dump quadrupole based on the 70 mm four layer coil proposed for the LHC low-ß quadrupoles. In preparation for model construction, we report on improvements of the coil design and a study of the retaining structures.

CESAR, 2 MeV electron storage ring; construction period; quadrupole.

CERN Multimedia

Service Photo; CERN PhotoLab

1962-01-01

One of the 24 quadrupoles. They were made of massive (non-laminated) soft iron, which at the low field-strength (35 G on the pole-tips) presented problems. Later they were fitted with shims on all 4 poles, to correct the quadrupole and sextupole components.

Excitation of giant monopole and quadrupole resonances

Energy Technology Data Exchange (ETDEWEB)

Ogata, H. [Osaka Univ., Suita (Japan). Research Center for Nuclear Physics; Yamagata, T.; Tanaka, M. [and others; Ikegami, H.; Muraoka, M. [eds.; Osaka Univ., Suita (Japan). Research Center for Nuclear Physics

1980-01-01

Recent studies on the giant monopole resonance (GMR) and the giant quadrupole resonance (GQR) in /sup 144/Sm and /sup 208/Pb using the ..cap alpha..-scattering performed at RCNP are summarized. The observed angular range covered 1.6/sup 0/ -- 7/sup 0/ with a coupled system of a dipole and a triplet quadrupole magnet. The incident energy was changed from 84 to 119 MeV. The resonance shapes and energy-weighted sum-rule strengths of the GMR and the GQR were reliably deduced as a function of incident energy. The quadrupole strength of --20% was found in the GMR region. The observed excitation function of the GMR was compared with the DWBA calculation, in which the Satchler's Version I was used as a form factor representing the compressional motion of the nucleus. It was found that the experimental excitation function of the GMR shows steeper decrease as lowering the incident energy than the DWBA prediction whereas that of the GQR is successfully described by the DWBA. This suggests that examination of the model describing the GMR is necessary.

Puzzle of the 6Li Quadrupole Moment: Steps toward Solving It

International Nuclear Information System (INIS)

Blokhintsev, L.D.; Kukulin, V.I.; Pomerantsev, V.N.

2005-01-01

The problem of the origin of the quadrupole deformation in the 6 Li ground state is investigated with allowance for the three-deuteron component of the 6 Li wave function. Two long-standing puzzles related to the tensor interaction in the 6 Li nucleus are known: that of an anomalous smallness of the 6 Li quadrupole moment (being negative, it is smaller in magnitude than the 7 Li quadrupole moment by a factor of 5) and that of an anomalous behavior of the tensor analyzing power T 2q in the scattering of polarized 6 Li nuclei on various targets. It is shown that a large (in magnitude) negative exchange contribution to the 6 Li quadrupole moment from the three-deuteron configuration cancels almost completely the 'direct' positive contribution due to the αd folding potential. As a result, the total quadrupole moment proves to be close to zero and highly sensitive to fine details of the tensor nucleon-nucleon interaction in the 4 He nucleus and of its wave function

Oscillatory ripples, evaluation of ancient wave climates and ...

African Journals Online (AJOL)

Oscillatory ripples, evaluation of ancient wave climates and epierogeny in the Anambra ... conditions, epierogenic patterns and paleogeographic history of the basins. ... shallow and marked by low to moderate hydrodynamic energy conditions.

Oscillatory patterns in the light curves of five long-term monitored type 1 active galactic nuclei

Science.gov (United States)

Kovačević, Andjelka B.; Pérez-Hernández, Ernesto; Popović, Luka Č.; Shapovalova, Alla I.; Kollatschny, Wolfram; Ilić, Dragana

2018-04-01

New combined data of five well-known type 1 active galactic nuclei (AGNs) are probed with a novel hybrid method in a search for oscillatory behaviour. Additional analysis of artificial light curves obtained from the coupled oscillatory models gives confirmation for detected periods that could have a physical background. We find periodic variations in the long-term light curves of 3C 390.3, NGC 4151 and NGC 5548, and E1821 + 643, with correlation coefficients larger than 0.6. We show that the oscillatory patterns of two binary black hole candidates, NGC 5548 and E1821 + 643, correspond to qualitatively different dynamical regimes of chaos and stability, respectively. We demonstrate that the absence of oscillatory patterns in Arp 102B could be the result of a weak coupling between oscillatory mechanisms. This is the first good evidence that 3C 390.3 and Arp 102B, categorized as double-peaked Balmer line objects, have qualitative different dynamics. Our analysis shows a novelty in the oscillatory dynamical patterns of the light curves of these type 1 AGNs.

Effects from Unsaturated Zone Flow during Oscillatory Hydraulic Testing

Science.gov (United States)

Lim, D.; Zhou, Y.; Cardiff, M. A.; Barrash, W.

2014-12-01

In analyzing pumping tests on unconfined aquifers, the impact of the unsaturated zone is often neglected. Instead, desaturation at the water table is often treated as a free-surface boundary, which is simple and allows for relatively fast computation. Richards' equation models, which account for unsaturated flow, can be compared with saturated flow models to validate the use of Darcy's Law. In this presentation, we examine the appropriateness of using fast linear steady-periodic models based on linearized water table conditions in order to simulate oscillatory pumping tests in phreatic aquifers. We compare oscillatory pumping test models including: 1) a 2-D radially-symmetric phreatic aquifer model with a partially penetrating well, simulated using both Darcy's Law and Richards' Equation in COMSOL; and 2) a linear phase-domain numerical model developed in MATLAB. Both COMSOL and MATLAB models are calibrated to match oscillatory pumping test data collected in the summer of 2013 at the Boise Hydrogeophysical Research Site (BHRS), and we examine the effect of model type on the associated parameter estimates. The results of this research will aid unconfined aquifer characterization efforts and help to constrain the impact of the simplifying physical assumptions often employed during test analysis.

Information-geometric measures estimate neural interactions during oscillatory brain states

Directory of Open Access Journals (Sweden)

Yimin eNie

2014-02-01

Full Text Available The characterization of functional network structures among multiple neurons is essential to understanding neural information processing. Information geometry (IG, a theory developed for investigating a space of probability distributions has recently been applied to spike-train analysis and has provided robust estimations of neural interactions. Although neural firing in the equilibrium state is often assumed in these studies, in reality, neural activity is non-stationary. The brain exhibits various oscillations depending on cognitive demands or when an animal is asleep. Therefore, the investigation of the IG measures during oscillatory network states is important for testing how the IG method can be applied to real neural data. Using model networks of binary neurons or more realistic spiking neurons, we studied how the single- and pairwise-IG measures were influenced by oscillatory neural activity. Two general oscillatory mechanisms, externally driven oscillations and internally induced oscillations, were considered. In both mechanisms, we found that the single-IG measure was linearly related to the magnitude of the external input, and that the pairwise-IG measure was linearly related to the sum of connection strengths between two neurons. We also observed that the pairwise-IG measure was not dependent on the oscillation frequency. These results are consistent with the previous findings that were obtained under the equilibrium conditions. Therefore, we demonstrate that the IG method provides useful insights into neural interactions under the oscillatory condition that can often be observed in the real brain.

Nuclear quadrupole interactions in ferroelectric compounds of HF181

International Nuclear Information System (INIS)

Kunzler, J.V.

1971-01-01

Measurements of nuclear quadrupole interaction constants in perovkite-type compounds of PbHfO 3 , SnhfO 3 , CaHfO 3 e SrHfO 3 have been performed using the perturbed angular correlation technique. A range of fundamental frequencies from 150 to 550 Megaradians persecond was determined. The variation of quadrupole constants has been discussed through the molecular orbital theory

Beam self-excited rf cavity driver for a deflector or focusing system

International Nuclear Information System (INIS)

Wadlinger, E.A.

1996-01-01

A bunched beam from and accelerator can excite and power an rf cavity which then drives either a deflecting or focusing (including nonlinear focusing) rf cavity with and amplitude related to beam current. Rf power, generated when a bunched beam loses energy to an rf field when traversing an electric field that opposes the particle's motion, is used to drive a separate (or the same) cavity to either focus or deflect the beam. The deflected beam can be stopped by an apertures or directed to a different area of a target depending on beam current. The beam-generated rf power can drive a radio-frequency quadrupole (RFQ) that can change the focusing properties of a beam channel as a function of beam current (space- charge force compensation or modifying the beam distribution on a target). An rf deflector can offset a beam to a downstream sextupole, effectively producing a position-dependent quadrupole field. The combination of rf deflector plus sextupole will produce a beam current dependent quadropole-focusing force. A static quadrupole magnet plus another rf deflector can place the beam back on the optic axis. This paper describes the concept, derives the appropriate equations for system analysis, and fives examples. A variation on this theme is to use the wake field generated in an rf cavity to cause growth in the beam emittance. The beam current would then be apertured by emittance defining slits

Activation energies as the validity criterion of a model for complex reactions that can be in oscillatory states

Directory of Open Access Journals (Sweden)

Anić S.

2007-01-01

Full Text Available Modeling of any complex reaction system is a difficult task. If the system under examination can be in various oscillatory dynamic states, the apparent activation energies corresponding to different pathways may be of crucial importance for this purpose. In that case the activation energies can be determined by means of the main characteristics of an oscillatory process such as pre-oscillatory period, duration of the oscillatory period, the period from the beginning of the process to the end of the last oscillation, number of oscillations and others. All is illustrated on the Bray-Liebhafsky oscillatory reaction.

Psychoacoustic Tinnitus Loudness and Tinnitus-Related Distress Show Different Associations with Oscillatory Brain Activity

Science.gov (United States)

Balkenhol, Tobias; Wallhäusser-Franke, Elisabeth; Delb, Wolfgang

2013-01-01

Background The phantom auditory perception of subjective tinnitus is associated with aberrant brain activity as evidenced by magneto- and electroencephalographic studies. We tested the hypotheses (1) that psychoacoustically measured tinnitus loudness is related to gamma oscillatory band power, and (2) that tinnitus loudness and tinnitus-related distress are related to distinct brain activity patterns as suggested by the distinction between loudness and distress experienced by tinnitus patients. Furthermore, we explored (3) how hearing impairment, minimum masking level, and (4) psychological comorbidities are related to spontaneous oscillatory brain activity in tinnitus patients. Methods and Findings Resting state oscillatory brain activity recorded electroencephalographically from 46 male tinnitus patients showed a positive correlation between gamma band oscillations and psychoacoustic tinnitus loudness determined with the reconstructed tinnitus sound, but not with the other psychoacoustic loudness measures that were used. Tinnitus-related distress did also correlate with delta band activity, but at electrode positions different from those associated with tinnitus loudness. Furthermore, highly distressed tinnitus patients exhibited a higher level of theta band activity. Moreover, mean hearing loss between 0.125 kHz and 16 kHz was associated with a decrease in gamma activity, whereas minimum masking levels correlated positively with delta band power. In contrast, psychological comorbidities did not express significant correlations with oscillatory brain activity. Conclusion Different clinically relevant tinnitus characteristics show distinctive associations with spontaneous brain oscillatory power. Results support hypothesis (1), but exclusively for the tinnitus loudness derived from matching to the reconstructed tinnitus sound. This suggests to preferably use the reconstructed tinnitus spectrum to determine psychoacoustic tinnitus loudness. Results also support

Beta and gamma oscillatory activities associated with olfactory memory tasks: different rhythms for different functional networks?

Science.gov (United States)

Martin, Claire; Ravel, Nadine

2014-01-01

Olfactory processing in behaving animals, even at early stages, is inextricable from top down influences associated with odor perception. The anatomy of the olfactory network (olfactory bulb, piriform, and entorhinal cortices) and its unique direct access to the limbic system makes it particularly attractive to study how sensory processing could be modulated by learning and memory. Moreover, olfactory structures have been early reported to exhibit oscillatory population activities easy to capture through local field potential recordings. An attractive hypothesis is that neuronal oscillations would serve to "bind" distant structures to reach a unified and coherent perception. In relation to this hypothesis, we will assess the functional relevance of different types of oscillatory activity observed in the olfactory system of behaving animals. This review will focus primarily on two types of oscillatory activities: beta (15-40 Hz) and gamma (60-100 Hz). While gamma oscillations are dominant in the olfactory system in the absence of odorant, both beta and gamma rhythms have been reported to be modulated depending on the nature of the olfactory task. Studies from the authors of the present review and other groups brought evidence for a link between these oscillations and behavioral changes induced by olfactory learning. However, differences in studies led to divergent interpretations concerning the respective role of these oscillations in olfactory processing. Based on a critical reexamination of those data, we propose hypotheses on the functional involvement of beta and gamma oscillations for odor perception and memory.

Beta and gamma oscillatory activities associated with olfactory memory tasks: Different rhythms for different functional networks?

Directory of Open Access Journals (Sweden)

Claire eMartin

2014-06-01

Full Text Available Olfactory processing in behaving animals, even at early stages, is inextricable from top down influences associated with odor perception. The anatomy of the olfactory network (olfactory bulb, piriform and entorhinal cortices and its unique direct access to the limbic system makes it particularly attractive to study how sensory processing could be modulated by learning and memory. Moreover, olfactory structures have been early reported to exhibit oscillatory population activities easy to capture through local field potential recordings. An attractive hypothesis is that neuronal oscillations would serve to ‘bind’ distant structures to reach a unified and coherent perception. In relation to this hypothesis, we will assess the functional relevance of different types of oscillatory activity observed in the olfactory system of behaving animals. This review will focus primarily on two types of oscillatory activities: beta (15-40 Hz and gamma (60-100 Hz. While gamma oscillations are dominant in the olfactory system in the absence of odorant, both beta and gamma rhythms have been reported to be modulated depending on the nature of the olfactory task. Studies from the authors of the present review and other groups brought evidence for a link between these oscillations and behavioral changes induced by olfactory learning. However, differences in studies led to divergent interpretations concerning the respective role of these oscillations in olfactory processing. Based on a critical reexamination of those data, we propose hypotheses on the functional involvement of beta and gamma oscillations for odor perception and memory.

Comparison of conventional and novel quadrupole drift tube magnets inspired by Klaus Halbach

Energy Technology Data Exchange (ETDEWEB)

Feinberg, B. [Lawrence Berkeley Lab., CA (United States)

1995-02-01

Quadrupole drift tube magnets for a heavy-ion linac provide a demanding application of magnet technology. A comparison is made of three different solutions to the problem of providing an adjustable high-field-strength quadrupole magnet in a small volume. A conventional tape-wound electromagnet quadrupole magnet (conventional) is compared with an adjustable permanent-magnet/iron quadrupole magnet (hybrid) and a laced permanent-magnet/iron/electromagnet (laced). Data is presented from magnets constructed for the SuperHILAC heavy-ion linear accelerator, and conclusions are drawn for various applications.

Distinction between perceptual and attentional processing in working memory tasks: a study of phase-locked and induced oscillatory brain dynamics.

Science.gov (United States)

Deiber, Marie-Pierre; Missonnier, Pascal; Bertrand, Olivier; Gold, Gabriel; Fazio-Costa, Lara; Ibañez, Vicente; Giannakopoulos, Panteleimon

2007-01-01

Working memory involves the short-term storage and manipulation of information necessary for cognitive performance, including comprehension, learning, reasoning and planning. Although electroencephalogram (EEG) rhythms are modulated during working memory, the temporal relationship of EEG oscillations with the eliciting event has not been well studied. In particular, the dynamics of the neural network supporting memory processes may be best captured in induced oscillations, characterized by a loose temporal link with the stimulus. In order to differentiate induced from evoked functional processes, the present study proposes a time-frequency analysis of the 3 to 30 Hz EEG oscillatory activity in a verbal n-back working memory paradigm. Control tasks were designed to identify oscillatory activity related to stimulus presentation (passive task) and focused attention to the stimulus (detection task). Evoked theta activity (4-8 Hz) phase-locked to the visual stimulus was evidenced in the parieto-occipital region for all tasks. In parallel, induced theta activity was recorded in the frontal region for detection and n-back memory tasks, but not for the passive task, suggesting its dependency on focused attention to the stimulus. Sustained induced oscillatory activity was identified in relation to working memory in the theta and beta (15-25 Hz) frequency bands, larger for the highest memory load. Its late occurrence limited to nonmatched items suggests that it could be related to item retention and active maintenance for further task requirements. Induced theta and beta activities displayed respectively a frontal and parietal topographical distribution, providing further functional information on the fronto-posterior network supporting working memory.

Dynamical quadrupole structure factor of frustrated ferromagnetic chain

Science.gov (United States)

Onishi, Hiroaki

2018-05-01

We investigate the dynamical quadrupole structure factor of a spin-1/2 J1-J2 Heisenberg chain with competing ferromagnetic J1 and antiferromagnetic J2 in a magnetic field by exploiting density-matrix renormalization group techniques. In a field-induced spin nematic regime, we observe gapless excitations at q = π according to quasi-long-range antiferro-quadrupole correlations. The gapless excitation mode has a quadratic form at the saturation, while it changes into a linear dispersion as the magnetization decreases.

Oscillatory Dynamics of One-Dimensional Homogeneous Granular Chains

Science.gov (United States)

Starosvetsky, Yuli; Jayaprakash, K. R.; Hasan, Md. Arif; Vakakis, Alexander F.

The acoustics of the homogeneous granular chains has been studied extensively both numerically and experimentally in the references cited in the previous chapters. This chapter focuses on the oscillatory behavior of finite dimensional homogeneous granular chains. It is well known that normal vibration modes are the building blocks of the vibrations of linear systems due to the applicability of the principle of superposition. One the other hand, nonlinear theory is deprived of such a general superposition principle (although special cases of nonlinear superpositions do exist), but nonlinear normal modes ‒ NNMs still play an important role in the forced and resonance dynamics of these systems. In their basic definition [1], NNMs were defined as time-periodic nonlinear oscillations of discrete or continuous dynamical systems where all coordinates (degrees-of-freedom) oscillate in-unison with the same frequency; further extensions of this definition have been considered to account for NNMs of systems with internal resonances [2]...

Quadrupole moment of the superdeformed band in 131Ce

International Nuclear Information System (INIS)

He, Y.; Godfrey, M.J.; Jenkins, I.; Kirwan, A.J.; Nolan, P.J.

1990-01-01

A mean lifetime measurement has been carried out on the states in the superdeformed band found in 131 Ce using the Doppler shift attenuation method (DSAM). The measured intrinsic nuclear quadrupole moment is Q o approx= 6 eb, assuming constant deformation, which corresponds to a quadrupole deformation β 2 approx= 0.35. This is considerably smaller than the value deduced for 132 Ce. (author)

Oscillatory integrals on Hilbert spaces and Schroedinger equation with magnetic fields

International Nuclear Information System (INIS)

Albeverio, S.; Brzezniak, Z.

1994-01-01

We extend the theory of oscillatory integrals on Hilbert spaces (the mathematical version of ''Feynman path integrals'') to cover more general integrable functions, preserving the property of the integrals to have converging finite dimensional approximations. We give an application to the representation of solutions of the time dependent Schroedinger equation with a scalar and a magnetic potential by oscillatory integrals on Hilbert spaces. A relation with Ramer's functional in the corresponding probabilistic setting is found. (orig.)

Origin-independent calculation of quadrupole intensities in X-ray spectroscopy

International Nuclear Information System (INIS)

Bernadotte, Stephan; Atkins, Andrew J.; Jacob, Christoph R.

2012-01-01

For electronic excitations in the ultraviolet and visible range of the electromagnetic spectrum, the intensities are usually calculated within the dipole approximation, which assumes that the oscillating electric field is constant over the length scale of the transition. For the short wavelengths used in hard X-ray spectroscopy, the dipole approximation may not be adequate. In particular, for metal K-edge X-ray absorption spectroscopy (XAS), it becomes necessary to include higher-order contributions. In quantum-chemical approaches to X-ray spectroscopy, these so-called quadrupole intensities have so far been calculated by including contributions depending on the square of the electric-quadrupole and magnetic-dipole transition moments. However, the resulting quadrupole intensities depend on the choice of the origin of the coordinate system. Here, we show that for obtaining an origin-independent theory, one has to include all contributions that are of the same order in the wave vector consistently. This leads to two additional contributions depending on products of the electric-dipole and electric-octupole and of the electric-dipole and magnetic-quadrupole transition moments, respectively. We have implemented such an origin-independent calculation of quadrupole intensities in XAS within time-dependent density-functional theory, and demonstrate its usefulness for the calculation of metal and ligand K-edge XAS spectra of transition metal complexes.

Communication: On the isotope anomaly of nuclear quadrupole coupling in molecules

Science.gov (United States)

Filatov, Michael; Zou, Wenli; Cremer, Dieter

2012-10-01

The dependence of the nuclear quadrupole coupling constants (NQCC) on the interaction between electrons and a nucleus of finite size is theoretically analyzed. A deviation of the ratio of the NQCCs obtained from two different isotopomers of a molecule from the ratio of the corresponding bare nuclear electric quadrupole moments, known as quadrupole anomaly, is interpreted in terms of the logarithmic derivatives of the electric field gradient at the nuclear site with respect to the nuclear charge radius. Quantum chemical calculations based on a Dirac-exact relativistic methodology suggest that the effect of the changing size of the Au nucleus in different isotopomers can be observed for Au-containing molecules, for which the predicted quadrupole anomaly reaches values of the order of 0.1%. This is experimentally detectable and provides an insight into the charge distribution of non-spherical nuclei.

Oscillatory regime of avalanche particle detectors

International Nuclear Information System (INIS)

Lukin, K.A.; Cerdeira, H.A.; Colavita, A.A.

1995-06-01

We describe the model of an avalanche high energy particle detector consisting of two pn-junctions, connected through an intrinsic semiconductor with a reverse biased voltage applied. We show that this detector is able to generate the oscillatory response on the single particle passage through the structure. The possibility of oscillations leading to chaotic behaviour is pointed out. (author). 15 refs, 7 figs

Oscillatory phase dynamics in neural entrainment underpin illusory percepts of time.

Science.gov (United States)

Herrmann, Björn; Henry, Molly J; Grigutsch, Maren; Obleser, Jonas

2013-10-02

Neural oscillatory dynamics are a candidate mechanism to steer perception of time and temporal rate change. While oscillator models of time perception are strongly supported by behavioral evidence, a direct link to neural oscillations and oscillatory entrainment has not yet been provided. In addition, it has thus far remained unaddressed how context-induced illusory percepts of time are coded for in oscillator models of time perception. To investigate these questions, we used magnetoencephalography and examined the neural oscillatory dynamics that underpin pitch-induced illusory percepts of temporal rate change. Human participants listened to frequency-modulated sounds that varied over time in both modulation rate and pitch, and judged the direction of rate change (decrease vs increase). Our results demonstrate distinct neural mechanisms of rate perception: Modulation rate changes directly affected listeners' rate percept as well as the exact frequency of the neural oscillation. However, pitch-induced illusory rate changes were unrelated to the exact frequency of the neural responses. The rate change illusion was instead linked to changes in neural phase patterns, which allowed for single-trial decoding of percepts. That is, illusory underestimations or overestimations of perceived rate change were tightly coupled to increased intertrial phase coherence and changes in cerebro-acoustic phase lag. The results provide insight on how illusory percepts of time are coded for by neural oscillatory dynamics.

Modelling and measurements of sand transport processes over full-scale ripples in oscillatory flow

NARCIS (Netherlands)

van der Werf, Jebbe J.; Ribberink, Jan S.; O'Donoghue, Tom; Doucette, Jeffrey C.

2006-01-01

A new series of laboratory experiments was performed in the Aberdeen Oscillatory Flow Tunnel (AOFT) and the Large Oscillating Water Tunnel (LOWT) to investigate time-averaged suspended sand concentrations and transport rates over rippled beds in regular and irregular oscillatory flow. The

Bias-dependent oscillatory electron transport of monatomic sulfur chains

KAUST Repository

Yu, Jing-Xin; Cheng, Yan; Sanvito, Stefano; Chen, Xiang-Rong

2012-01-01

The bias-dependent oscillatory electron transport of monatomic sulfur chains sandwiched between gold electrodes is investigated with density functional theory and non-equilibrium Green's function method. At zero bias, in contrast to the typical odd-even oscillations observed in most metallic chains, we find that the conductance oscillates with a period of four atoms. However, as the bias voltage is increased the current displays a two-atom periodicity. This emerges gradually, first for the longer chains and then, at voltages larger than 0.7 V, for lengths. The oscillatory behaviors are analyzed by the density of states and the energy-dependent and bias-dependent transmission coefficients. © 2012 American Institute of Physics.

Bias-dependent oscillatory electron transport of monatomic sulfur chains

KAUST Repository

Yu, Jing-Xin

2012-01-01

The bias-dependent oscillatory electron transport of monatomic sulfur chains sandwiched between gold electrodes is investigated with density functional theory and non-equilibrium Green\\'s function method. At zero bias, in contrast to the typical odd-even oscillations observed in most metallic chains, we find that the conductance oscillates with a period of four atoms. However, as the bias voltage is increased the current displays a two-atom periodicity. This emerges gradually, first for the longer chains and then, at voltages larger than 0.7 V, for lengths. The oscillatory behaviors are analyzed by the density of states and the energy-dependent and bias-dependent transmission coefficients. © 2012 American Institute of Physics.

Calculation of the quadrupole-lense fringing field

International Nuclear Information System (INIS)

Arzumanov, A.A.

1978-01-01

With the aim of decreasing the scattering field effect at electrode edge or quadrupole lens poles with conformal transformations the scattering fields of electric quadrupole lens, two-electrode lens with the electrodes in a hyperbola form, as well as magnetic lens with hyperbolic poles are calculated. For the two-electrode system with kappa=0.1 (kappa - is coefficient, characterizing the rate of field intensity change in the lens) field distortion equals 1.8%. The comparison of experimental data with the calculation data has shown that with a rather high accuracy the scattering field effect in electric and magnetic lenses with hyperbolic poles may be taken into account

A magnetic focusing channel for VEC at Calcutta

International Nuclear Information System (INIS)

Mallik, C.

1986-01-01

The extent of the useful aperture of a beam handling quadrupole magnet of the variable energy cyclotron at Calcutta is about 6 cms, but the extent of the beam in radial plane near the entrance to the quadrupole is at least 10 cm i.e. it exceeds the size of the useful aperture. This creates the problem of phase space distortion decreasing the efficiency of the beam transport line and the usable beam. To correct this problem, a triplet bar has been used as a magnetic focusing channel. The magnetic field induced due to this bar in the median plane is shown in a figure and advantages of its use are described. (M.G.B.)

Quadrupole moment in the excited 2Psub(1/2) state

International Nuclear Information System (INIS)

Amusia, M.Ya.; Yakhontov, V.L.

1984-01-01

Computation of the quadrupole moment values in the 2Psub(1/2) states of hydrogen and meso-hydrogen is carried out. It is shown that allowance for the hyperfine interaction of the electron with the proton in the first order of perturbation theory results in giant values of the quadrupole moment of the atoms. (author)

Design of high-energy high-current linac with focusing by superconducting solenoids

Energy Technology Data Exchange (ETDEWEB)

Batskikh, G.I.; Belugin, V.M.; Bondarev, B.I. [Moscow Radiotechnical Institute (Russian Federation)] [and others

1995-10-01

The advancement of MRTI design for 1.5 GeV and 250 mA ion CW linac was presented in a previous report. In this new linac version all the way from input to output the ions are focused by magnetic fields of superconducting solenoids. The ion limit current is far beyond the needed value. The linac focusing channel offers major advantages over the more conventional ones. The acceptance is 1.7 times as large for such focusing channel as for quadrupole one. Concurrently, a random perturbation sensitivity for such channel is one order of magnitude smaller than in quadrupole channel. These focusing channel features allow to decrease beam matched radius and increase a linac radiation purity without aperture growth. {open_quotes}Regotron{close_quotes} is used as high power generator in linac main part. But D&W cavities need not be divided into sections connected by RF-bridges which denuded them of high coupling factor.

Direct focusing error correction with ring-wide TBT beam position data

International Nuclear Information System (INIS)

Yang, M.J.

2011-01-01

Turn-By-Turn (TBT) betatron oscillation data is a very powerful tool in studying machine optics. Hundreds and thousands of turns of free oscillations are taken in just few tens of milliseconds. With beam covering all positions and angles at every location TBT data can be used to diagnose focusing errors almost instantly. This paper describes a new approach that observes focusing error collectively over all available TBT data to find the optimized quadrupole strength, one location at a time. Example will be shown and other issues will be discussed. The procedure presented clearly has helped to reduce overall deviations significantly, with relative ease. Sextupoles, being a permanent feature of the ring, will need to be incorporated into the model. While cumulative effect from all sextupoles around the ring may be negligible on turn-to-turn basis it is not so in this transfer line analysis. It should be noted that this procedure is not limited to looking for quadrupole errors. By modifying the target of minimization it could in principle be used to look for skew quadrupole errors and sextupole errors as well.

[Recent results in research on oscillatory chemical reactions].

Science.gov (United States)

Poros, Eszter; Kurin-Csörgei, Krisztina

2014-01-01

The mechanisms of the complicated periodical phenomenas in the nature (e.g. hearth beat, sleep cycle, circadian rhythms, etc) could be understood with using the laws of nonlinear chemical systems. In this article the newest result in the research of the subfield of nonlinear chemical dynamics aimed at constructing oscillatory chemical reactions, which are novel either in composition or in configuration, are presented. In the introductory part the concept of chemical periodicity is defined, then the forms as it can appear in time and space and the methods of their study are discussed. Detailed description of the experimental work that has resulted in two significant discoveries is provided. A method was developed to design pH-oscillators which are capable of operating under close conditions. The batch pH-oscillators are more convenient to use in some proposed applications than the equivalent CSTR variant. A redox oscillator that is new in composition was found. The permanganate oxidation of some amino acids was shown to take place according to oscillatory kinetics in a narrow range of the experimental parameters. The KMnO4 - glycine - Na2HPO4 system represents the first example in the family of manganese based oscillators where amino acids is involved. In the conclusion formal analogies between the simple chemical and some more complicated biological oscillatory phenomena are mentioned and the possibility of modeling periodic processes with the use of information gained from the studies of chemical oscillations is pointed out.

Accelerating and focusing structures for PIGMI

International Nuclear Information System (INIS)

Swenson, D.A.; Bush, E.D. Jr.; Holsinger, R.F.; Manca, J.J.; Saito, N.; Stovall, J.E.

1977-01-01

The National Cancer Institute is supporting a program of accelerator development at the Los Alamos Scientific Laboratory aimed at the extension of proton linac technologies to produce the most suitable Pion Generator for Medical Irradiations (PIGMI). An optimized design of a pion generator suitable for a radiotherapy program at a major medical center has been established, consisting of a 250-keV injector, followed by a 35-meter-long drift-tube linac that accelerates the proton beam to 150 MeV, and an 85-meter-long coupled-cavity linac that accelerates the beam to its final energy of 650 MeV, where the average beam current of 100 microamperes impinges on one or more targets producing abundant quantities of π - mesons for radiotherapeutic applications. A number of extensions to proton linac technology are being pursued under the PIGMI program at LASL. A discussion is given of recent developments in three areas relevant to the acceleration and focusing of proton beams, namely, the alternating phase focused (APF) linac structure, the disk and washer linac structure, and small permanent magnet quadrupole lenses. The APF linac structure is being developed for the acceleration and focusing role from the injection energy of 250 keV to a few MeV, where a transition is made to a permanent magnet quadrupole focused linac structure. The disk and washer linac structure is under consideration for the high velocity portion of the design

Stability of the coherent quadrupole oscillations excited by the beam-beam interaction

International Nuclear Information System (INIS)

Kamiya, Y.; Chao, A.W.

1983-10-01

We study the coherent quadrupole motion in the presence of beam-beam interaction, using a linear approximation to the beam-beam force. The corresponding beam-beam limit is determined by evaluating the eigenvalues of a system of linear equations describing the coherent quadrupole motion. We find that the stability of the quadrupole motions imposes severe limits on the beam current, as is the case for the dipole instability. Preliminary results of this study have appeared elsewhere

On quantum quadrupole radiation

International Nuclear Information System (INIS)

Fonda, L.; Mankoc-Borstnik, N.

1981-02-01

In this paper it is shown that for the electromagnetic decay of a quantum system in a coherent rotational state the total quadrupole radiation is proportional to (d 5 Q/dt 5 )(dQ/dt)sup(*)+c.c. For the radiation flux out of a sphere of large radius a different quantity, closer to the classical expression (d 3 Q/dt 3 ) 2 , is found. (author)

Resting-state oscillatory brain dynamics in Alzheimer disease

NARCIS (Netherlands)

de Haan, W.; Stam, C.J.; Jones, B.F.; Zuiderwijk, I.M.; van Dijk, B.W.; Scheltens, P.

2008-01-01

Altered oscillatory brain activity in Alzheimer disease (AD) may reflect underlying neuropathological changes, and its characterization might lead to new diagnostic possibilities. The present study using quantitative magnetoencephalography was set up to examine power spectrum changes in AD patients,

Grasping hand verbs: oscillatory beta and alpha correlates of action-word processing.

Directory of Open Access Journals (Sweden)

Valentina Niccolai

Full Text Available The grounded cognition framework proposes that sensorimotor brain areas, which are typically involved in perception and action, also play a role in linguistic processing. We assessed oscillatory modulation during visual presentation of single verbs and localized cortical motor regions by means of isometric contraction of hand and foot muscles. Analogously to oscillatory activation patterns accompanying voluntary movements, we expected a somatotopically distributed suppression of beta and alpha frequencies in the motor cortex during processing of body-related action verbs. Magnetoencephalographic data were collected during presentation of verbs that express actions performed using the hands (H or feet (F. Verbs denoting no bodily movement (N were used as a control. Between 150 and 500 msec after visual word onset, beta rhythms were suppressed in H and F in comparison with N in the left hemisphere. Similarly, alpha oscillations showed left-lateralized power suppression in the H-N contrast, although at a later stage. The cortical oscillatory activity that typically occurs during voluntary movements is therefore found to somatotopically accompany the processing of body-related verbs. The combination of a localizer task with the oscillatory investigation applied to verb reading as in the present study provides further methodological possibilities of tracking language processing in the brain.

The Erez–Rosen metric and the role of the quadrupole on light propagation

International Nuclear Information System (INIS)

Bini, Donato; Crosta, Mariateresa; Vecchiato, Alberto; De Felice, Fernando; Geralico, Andrea

2013-01-01

The gravitational field of a static body with the quadrupole moment is described by an exact solution found by Erez and Rosen. Here, we investigate the role of the quadrupole in the motion, deflection and lensing of a light ray in the above metric. The standard lensing observables such as image positions and magnification have been explicitly obtained in the weak-field and small-quadrupole limit. In this limit, the spacetime metric appears as the natural generalization to quadrupole corrections of the metric form adopted also in current astrometric models. Hence, the corresponding analytical solution of the inverse ray tracing problem and the consistency with other approaches are also discussed. (paper)

Oscillatory magnetoconductance of quantum double-well channels

International Nuclear Information System (INIS)

Rojo, A.G.; Kumar, N.; Balseiro, C.A.

1988-07-01

The recently observed flux-periodic interference effect between parallel quantum double-well channels is theoretically studied in a discrete model that takes into account tunneling between channels. We obtain oscillatory magnetoconductance with small modulations which is attributable to the tunneling. Our treatment includes the effect of evanescent modes. (author). 7 refs, 2 figs

Oscillatory behaviors and hierarchical assembly of contractile structures in intercalating cells

International Nuclear Information System (INIS)

Fernandez-Gonzalez, Rodrigo; Zallen, Jennifer A

2011-01-01

Fluctuations in the size of the apical cell surface have been associated with apical constriction and tissue invagination. However, it is currently not known if apical oscillatory behaviors are a unique property of constricting cells or if they constitute a universal feature of the force balance between cells in multicellular tissues. Here, we set out to determine whether oscillatory cell behaviors occur in parallel with cell intercalation during the morphogenetic process of axis elongation in the Drosophila embryo. We applied multi-color, time-lapse imaging of living embryos and SIESTA, an integrated tool for automated and semi-automated cell segmentation, tracking, and analysis of image sequences. Using SIESTA, we identified cycles of contraction and expansion of the apical surface in intercalating cells and characterized them at the molecular, cellular, and tissue scales. We demonstrate that apical oscillations are anisotropic, and this anisotropy depends on the presence of intact cell–cell junctions and spatial cues provided by the anterior–posterior patterning system. Oscillatory cell behaviors during axis elongation are associated with the hierarchical assembly and disassembly of contractile actomyosin structures at the medial cortex of the cell, with actin localization preceding myosin II and with the localization of both proteins preceding changes in cell shape. We discuss models to explain how the architecture of cytoskeletal networks regulates their contractile behavior and the mechanisms that give rise to oscillatory cell behaviors in intercalating cells

Analysis of magnetic nanoparticles using quadrupole magnetic field-flow fractionation

International Nuclear Information System (INIS)

Carpino, Francesca; Moore, Lee R.; Zborowski, Maciej; Chalmers, Jeffrey J.; Williams, P. Stephen

2005-01-01

The new technique of quadrupole magnetic field-flow fractionation is described. It is a separation and characterization technique for particulate magnetic materials. Components of a sample are eluted from the separation channel at times dependent on the strength of their interaction with the magnetic field. A quadrupole electromagnet allows a programmed reduction of field strength during analysis of polydisperse samples

Approximate damped oscillatory solutions and error estimates for the perturbed Klein–Gordon equation

International Nuclear Information System (INIS)

Ye, Caier; Zhang, Weiguo

2015-01-01

Highlights: • Analyze the dynamical behavior of the planar dynamical system corresponding to the perturbed Klein–Gordon equation. • Present the relations between the properties of traveling wave solutions and the perturbation coefficient. • Obtain all explicit expressions of approximate damped oscillatory solutions. • Investigate error estimates between exact damped oscillatory solutions and the approximate solutions and give some numerical simulations. - Abstract: The influence of perturbation on traveling wave solutions of the perturbed Klein–Gordon equation is studied by applying the bifurcation method and qualitative theory of dynamical systems. All possible approximate damped oscillatory solutions for this equation are obtained by using undetermined coefficient method. Error estimates indicate that the approximate solutions are meaningful. The results of numerical simulations also establish our analysis

Solvent Fermentation From Palm Oil Mill Effluent Using Clostridium acetobutylicum In Oscillatory Flow Bioreactor

International Nuclear Information System (INIS)

Takriff, M.S.; Masngut, N.; Kadhum, A.A.H.; Kalil, M.S.; Mohammad, A.W.

2009-01-01

Acetone-butanol-ethanol (ABE) fermentation from Palm Oil Mill Effluent (POME) by C. acetobutylicum NCIMB 13357 in an oscillatory flow bioreactor was investigated. Experimental works were conducted in a U-shaped stainless steel oscillatory flow bioreactor at oscillation frequency between 0.45-0.78 Hz and a constant amplitude of 12.5 mm. Fermentations were carried out for 72 hr at 35 degree Celsius using palm oil mill effluent and reinforced clostridia medium as a growth medium in batch culture. Result of this investigation showed that POME is a viable media for ABE fermentation and oscillatory flow bioreactor has an excellent potential as an alternative fermentation device. (author)

Mechanical Design of a Second Generation LHC IR Quadrupole

International Nuclear Information System (INIS)

Caspi, S.; Bartlett, S.E.; Dietderich, D.R.; Ferracin, P.; Gourlay, S.A.; Hafalia, R.R.; Hannaford, C.R.; Lietzke, A.F.; McInturff, A.D.; Sabbi, G.; Scanlan, R.M.

2003-01-01

One of the proposed options to increase the LHC luminosity is the replacement of the existing inner triplets at the Interaction Regions with new low-beta larger aperture quadrupoles operating at the same gradient. Lawrence Berkeley National Laboratory (LBNL) is carrying out preliminary studies of a large-bore Nb 3 Sn quadrupole. The mechanical design presents a support structure based on the use of keys and bladders without self-supporting collars. This technology has been proven effective in several successful common coil Nb 3 Sn dipoles built at LBNL, and it is for the first time applied to a cos(2(var t heta)) design. In this paper we present a detailed analysis of the quadrupole mechanical behavior, demonstrating the possibility of delivering, through this method, well-controlled coil precompression during assembly, cool-down and excitation. The study has been performed with the finite element program ANSYS

Capacity of oscillatory associative-memory networks with error-free retrieval

International Nuclear Information System (INIS)

Nishikawa, Takashi; Lai Yingcheng; Hoppensteadt, Frank C.

2004-01-01

Networks of coupled periodic oscillators (similar to the Kuramoto model) have been proposed as models of associative memory. However, error-free retrieval states of such oscillatory networks are typically unstable, resulting in a near zero capacity. This puts the networks at disadvantage as compared with the classical Hopfield network. Here we propose a simple remedy for this undesirable property and show rigorously that the error-free capacity of our oscillatory, associative-memory networks can be made as high as that of the Hopfield network. They can thus not only provide insights into the origin of biological memory, but can also be potentially useful for applications in information science and engineering

Study on pulsed-operation of the drift tube quadrupole magnets

International Nuclear Information System (INIS)

Mutou, M.

1982-01-01

The heavy ion linac for NUMATRON project is designed not only as a injector for a synchrotron but also as a supplier of heavy ion beams for experiments with linac beam. In one repetition cycle of the synchrotron (1sec), the linac injects nearly 25 beam pulses with pulse width of 300 μsec and pulse interval of 30 msec. And the ion species can be varied every repetition. On the other hand, when it is off duty of injection to the synchrotron, the linac accelerates the beams that are directly used for the experiments. Also in this case, the ion species should be varied according to the requests of the experiments, for instance every 1 sec. Therefore, the quadrupole magnets installed in the drift tubes of the linac must be excited with pulse mode. The power supply of the quadrupole magnets will consists of two parts, namely pulse-excitation and dc-excitation power sources. The report describes the posibilities on the pulse-operation of the quadrupole magnets with the field gradient of asymptotically equals 10 KG/cm, and the analysis of the power supply of the quadrupole magnets. (author)

Abnormal language-related oscillatory responses in primary progressive aphasia

Directory of Open Access Journals (Sweden)

A. Kielar

Full Text Available Patients with Primary Progressive Aphasia (PPA may react to linguistic stimuli differently than healthy controls, reflecting degeneration of language networks and engagement of compensatory mechanisms. We used magnetoencephalography (MEG to evaluate oscillatory neural responses in sentence comprehension, in patients with PPA and age-matched controls. Participants viewed sentences containing semantically and syntactically anomalous words that evoke distinct oscillatory responses. For age-matched controls, semantic anomalies elicited left-lateralized 8–30 Hz power decreases distributed along ventral brain regions, whereas syntactic anomalies elicited bilateral power decreases in both ventral and dorsal regions. In comparison to controls, patients with PPA showed altered patterns of induced oscillations, characterized by delayed latencies and attenuated amplitude, which were correlated with linguistic impairment measured offline. The recruitment of right hemisphere temporo-parietal areas (also found in controls was correlated with preserved semantic processing abilities, indicating that preserved neural activity in these regions was able to support successful semantic processing. In contrast, syntactic processing was more consistently impaired in PPA, regardless of neural activity patterns, suggesting that this domain of language is particularly vulnerable to the neuronal loss. In addition, we found that delayed peak latencies of oscillatory responses were associated with lower accuracy for detecting semantic anomalies, suggesting that language deficits observed in PPA may be linked to delayed or slowed information processing. Keywords: MEG oscillations, Primary progressive aphasia (PPA, Sentence comprehension

The role of high-frequency oscillatory activity in reward processing and learning.

Science.gov (United States)

Marco-Pallarés, Josep; Münte, Thomas F; Rodríguez-Fornells, Antoni

2015-02-01

Oscillatory activity has been proposed as a key mechanism in the integration of brain activity of distant structures. Particularly, high frequency brain oscillatory activity in the beta and gamma range has received increasing interest in the domains of attention and memory. In addition, a number of recent studies have revealed an increase of beta-gamma activity (20-35 Hz) after unexpected or relevant positive reward outcomes. In the present manuscript we review the literature on this phenomenon and we propose that this activity is a brain signature elicited by unexpected positive outcomes in order to transmit a fast motivational value signal to the reward network. In addition, we hypothesize that beta-gamma oscillatory activity indexes the interaction between attentional and emotional systems, and that it directly reflects the appearance of unexpected positive rewards in learning-related contexts. Copyright © 2014 Elsevier Ltd. All rights reserved.

Relaxation of quadrupole orientation in an optically pumped alkali vapour

Energy Technology Data Exchange (ETDEWEB)

Bernabeu, E; Tornos, J

1985-04-01

The relaxation of quadrupole orientation (alignment) in an optically pumped alkali vapour is theoretically studied by taking into account the relaxation processes by alkali-buffer gas, alkali-alkali with spin exchange and alkali-cell wall (diffusion process) collisions. The relaxation transients of the quadrupole orientation are obtained by introducing a first-order weak-pumping approximation (intermediate pumping) less restrictive than the usually considered (zeroth order) one.

Nuclear quadrupole interactions in ferroelectric compounds of HF/sup 181/

Energy Technology Data Exchange (ETDEWEB)

Kunzler, J V

1971-01-01

Measurements of nuclear quadrupole interaction constants in perovkite-type compounds of PbHfO/sub 3/, SnhfO/sub 3/, CaHfO/sub 3/ e SrHfO/sub 3/ have been performed using the perturbed angular correlation technique. A range of fundamental frequencies from 150 to 550 Megaradians per second was determined. The variation of quadrupole constants has been discussed through the molecular orbital theory.

Superconducting Quadrupole for the ISR High Luminosity insertion:end view

CERN Multimedia

1977-01-01

Connection end view of the prototype quadrupole before insertion of the inner vacuum chamber with inbedded 6-pole windings. The main components of the structure can be seen: (from inside outwards) the superconducting quadrupole coils surrounded by glass epoxy bandage rings and stainless steel spacers, the low-carbon steel yoke quadrants and the aluminium alloy shrinking rings. See also photos 7702690X, 7702307, 7702308, 7812604X.

Large Amplitude Oscillatory Extension of Soft Polymeric Networks

DEFF Research Database (Denmark)

Bejenariu, Anca Gabriela; Rasmussen, Henrik K.; Skov, Anne Ladegaard

2010-01-01

sing a filament stretching rheometer (FSR) surrounded by a thermostatic chamber and equipped with a micrometric laser it is possible to measure large amplitude oscillatory elongation (LAOE) on elastomeric based networks with no base flow as in the LAOE method for polymer melts. Poly(dimethylsilox...

Oscillatory and electrohydrodynamic instabilities in flow over a ...

Indian Academy of Sciences (India)

of fluid flow past flexible surfaces is qualitatively different from the flow over rigid .... work. Oscillatory flows are unsteady, and it is important to precisely define the ..... from 5 to 16, though there is less variation in the critical stress for a steady ...

Cracking the code of oscillatory activity.

Directory of Open Access Journals (Sweden)

Philippe G Schyns

2011-05-01

Full Text Available Neural oscillations are ubiquitous measurements of cognitive processes and dynamic routing and gating of information. The fundamental and so far unresolved problem for neuroscience remains to understand how oscillatory activity in the brain codes information for human cognition. In a biologically relevant cognitive task, we instructed six human observers to categorize facial expressions of emotion while we measured the observers' EEG. We combined state-of-the-art stimulus control with statistical information theory analysis to quantify how the three parameters of oscillations (i.e., power, phase, and frequency code the visual information relevant for behavior in a cognitive task. We make three points: First, we demonstrate that phase codes considerably more information (2.4 times relating to the cognitive task than power. Second, we show that the conjunction of power and phase coding reflects detailed visual features relevant for behavioral response--that is, features of facial expressions predicted by behavior. Third, we demonstrate, in analogy to communication technology, that oscillatory frequencies in the brain multiplex the coding of visual features, increasing coding capacity. Together, our findings about the fundamental coding properties of neural oscillations will redirect the research agenda in neuroscience by establishing the differential role of frequency, phase, and amplitude in coding behaviorally relevant information in the brain.

Shear and loading in channels: Oscillatory shearing and edge currents of superconducting vortices

Science.gov (United States)

Wambaugh, J. F.; Marchesoni, F.; Nori, Franco

2003-04-01

Via computer simulations we study the motion of quantized magnetic flux-lines, or vortices, confined to a straight pin-free channel in a strong-pinning superconducting sample. We find that, when a constant current is applied across this system, a very unusual oscillatory shearing appears, in which the vortices moving at the edges of the channel periodically trail behind and then suddenly leapfrog past the vortices moving in the inner rows. For small enough driving forces, this oscillatory shearing dynamic phase is replaced by a continuous shearing phase in which the distance between initially-nearby vortices grows in time, quickly destroying the order of the lattice. An animation of this novel “oscillatory leapfrogging shear” effect of the vortex edge currents appears in http://www-personal.engin.umich.edu/˜nori/channel/

Exploring the triplet parameters space to optimise the final focus of the FCC-hh

CERN Document Server

AUTHOR|(CDS)2141109; Abelleira, Jose; Seryi, Andrei; Cruz Alaniz, Emilia

2017-01-01

One of the main challenges when designing final focus systems of particle accelerators is maximising the beam stay clear in the strong quadrupole magnets of the inner triplet. Moreover it is desirable to keep the quadrupoles in the triplet as short as possible for space and costs reasons but also to reduce chromaticity and simplify corrections schemes. An algorithm that explores the triplet parameter space to optimise both these aspects was written. It uses thin lenses as a first approximation and MADX for more precise calculations. In cooperation with radiation studies, this algorithm was then applied to design an alternative triplet for the final focus of the Future Circular Collider (FCC-hh).

Compact high-field superconducting quadrupole magnet with holmium poles

Energy Technology Data Exchange (ETDEWEB)

Barlow, D.B.; Kraus, R.H. Jr.; Lobb, C.T.; Menzel, M.T. (Los Alamos National Lab., NM (United States)); Walstrom, P.L. (Grumman Space Systems, Los Alamos, NM (United States))

1992-03-15

A compact high-field superconducting quadrupole magnet was designed and built with poles made of the rare-earth metal holmium. The magnet is intended for use in superconducting coupled-cavity linear accelerators where compact high-field quadrupoles are needed, but where the use of permanent magnets is ruled out because of trapped-flux losses. The magnet has a clear bore diameter of 1.8 cm, outside diameter of 11 cm, length of 11 cm, and pole tip length of 6 cm. The effect of using holmium, a material with a higher saturation field than iron, was investigated by replacing poles made of iron with identical poles made of holmium. The magnet was operated at a temperature of 4.2 K and reached a peak quadrupole field gradient of 355 T/m, a 10% increase over the same magnet with iron poles. This increase in performance is consistent with calculations based on B-H curves that were measured for holmium at 4.2 K. (orig.).

Magnetic Focusing Horn

CERN Multimedia

1974-01-01

This magnetic focusing horn was used for the AA (antiproton accumulator). Its development was an important step towards using CERN's Super Proton Synchrotron as a proton - antiproton collider. This eventually led to the discovery of the W and Z particles in 1983. Making an antiproton beam took a lot of time and effort. Firstly, protons were accelerated to an energy of 26 GeV in the PS and ejected onto a metal target. From the spray of emerging particles, a magnetic horn picked out 3.6 GeV antiprotons for injection into the AA through a wide-aperture focusing quadrupole magnet. For a million protons hitting the target, just one antiproton was captured, 'cooled' and accumulated. It took 3 days to make a beam of 3 x 10^11 -, three hundred thousand million - antiprotons.

Direct Numerical Simulation of Oscillatory Flow Over a Wavy, Rough, and Permeable Bottom

Science.gov (United States)

Mazzuoli, Marco; Blondeaux, Paolo; Simeonov, Julian; Calantoni, Joseph

2018-03-01

The results of a direct numerical simulation of oscillatory flow over a wavy bottom composed of different layers of spherical particles are described. The amplitude of wavy bottom is much smaller in scale than typical bed forms such as sand ripples. The spherical particles are packed in such a way to reproduce a bottom profile observed during an experiment conducted in a laboratory flow tunnel with well-sorted coarse sand. The amplitude and period of the external forcing flow as well as the size of the particles are set equal to the experimental values and the computed velocity field is compared with the measured velocity profiles. The direct numerical simulation allows for the evaluation of quantities, which are difficult to measure in a laboratory experiment (e.g., vorticity, seepage flow velocity, and hydrodynamic force acting on sediment particles). In particular, attention is focused on the coherent vortex structures generated by the vorticity shed by both the spherical particles and the bottom waviness. Results show that the wavy bottom triggers transition to turbulence. Moreover, the forces acting on the spherical particles are computed to investigate the mechanisms through which they are possibly mobilized by the oscillatory flow. It was found that forces capable of mobilizing surface particles are strongly correlated with the particle position above the mean bed elevation and the passage of coherent vortices above them.

Proposed use of the radio-frequency quadrupole structure to funnel high-current ion beams

International Nuclear Information System (INIS)

Stokes, R.H.; Minerbo, G.N.

1985-01-01

In this paper, we describe a new approach to funneling beams that are initially accelerated in two radio-frequency quadrupole (RFQ) accelerators. Instead of discrete optical elements, we propose to funnel within an RFQ structure, so that during the funneling process the beam is always confined by periodic transverse focusing. Beams with high space charge experience irreversible emittance growth when they emerge from a periodic focusing system. To alleviate this problem, in the proposed funneling system it should be possible to maintain the same focusing periodicity as that of the accelerators preceding the funnel. Also, instead of conventional deflection systems, we propose to use the properties of a modified RFQ structure to deflect two parallel beams toward each other and to merge them into a single final beam. 1 ref., 3 figs

Flat super-oscillatory lens for heat-assisted magnetic recording with sub-50 nm resolution.

Science.gov (United States)

Yuan, Guanghui; Rogers, Edward T F; Roy, Tapashree; Shen, Zexiang; Zheludev, Nikolay I

2014-03-24

Heat-assisted magnetic recording (HAMR) is a future roadmap technology to overcome the superparamagnetic limit in high density magnetic recording. Existing HAMR schemes depend on a simultaneous magnetic stimulation and light-induced local heating of the information carrier. To achieve high-density recorded data, near-field plasmonic transducers have been proposed as light concentrators. Here we suggest and investigate in detail an alternative approach exploiting a far-field focusing device that can focus light into sub-50 nm hot-spots in the magnetic recording layer using a laser source operating at 473 nm. It is based on a recently introduced super-oscillatory flat lens improved with the use of solid immersion, giving an effective numerical aperture as high as 4.17. The proposed solution is robust and easy to integrate with the magnetic recording head thus offering a competitive advantage over plasmonic technology.

Oscillatory flow chemical reactors

Directory of Open Access Journals (Sweden)

Slavnić Danijela S.

2014-01-01

Full Text Available Global market competition, increase in energy and other production costs, demands for high quality products and reduction of waste are forcing pharmaceutical, fine chemicals and biochemical industries, to search for radical solutions. One of the most effective ways to improve the overall production (cost reduction and better control of reactions is a transition from batch to continuous processes. However, the reactions of interests for the mentioned industry sectors are often slow, thus continuous tubular reactors would be impractically long for flow regimes which provide sufficient heat and mass transfer and narrow residence time distribution. The oscillatory flow reactors (OFR are newer type of tube reactors which can offer solution by providing continuous operation with approximately plug flow pattern, low shear stress rates and enhanced mass and heat transfer. These benefits are the result of very good mixing in OFR achieved by vortex generation. OFR consists of cylindrical tube containing equally spaced orifice baffles. Fluid oscillations are superimposed on a net (laminar flow. Eddies are generated when oscillating fluid collides with baffles and passes through orifices. Generation and propagation of vortices create uniform mixing in each reactor cavity (between baffles, providing an overall flow pattern which is close to plug flow. Oscillations can be created by direct action of a piston or a diaphragm on fluid (or alternatively on baffles. This article provides an overview of oscillatory flow reactor technology, its operating principles and basic design and scale - up characteristics. Further, the article reviews the key research findings in heat and mass transfer, shear stress, residence time distribution in OFR, presenting their advantages over the conventional reactors. Finally, relevant process intensification examples from pharmaceutical, polymer and biofuels industries are presented.

Bifurcations of propellant burning rate at oscillatory pressure

Energy Technology Data Exchange (ETDEWEB)

Novozhilov, Boris V. [N. N. Semenov Institute of Chemical Physics, Russian Academy of Science, 4 Kosygina St., Moscow 119991 (Russian Federation)

2006-06-15

A new phenomenon, the disparity between pressure and propellant burning rate frequencies, has revealed in numerical studies of propellant burning rate response to oscillatory pressure. As is clear from the linear approximation, under small pressure amplitudes, h, pressure and propellant burning rate oscillations occur with equal period T (T-solution). In the paper, however, it is shown that at a certain critical value of the parameter h the system in hand undergoes a bifurcation so that the T-solution converts to oscillations with period 2T (2T-solution). When the bifurcation parameter h increases, the subsequent behavior of the system becomes complicated. It is obtained a sequence of period doubling to 4T-solution and 8T-solution. Beyond a certain value of the bifurcation parameter h an apparently fully chaotic solution is found. These effects undoubtedly should be taken into account in studies of oscillatory processes in combustion chambers. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

Construction and Qualification of the Pre-Series MQM Superconducting Quadrupoles for the LHC Insertions

CERN Document Server

Ostojic, R; Lucas, J; Venturini-Delsolaro, W; Landgrebe, D

2004-01-01

The LHC insertions will be equipped with individually powered MQM superconducting quadrupoles, produced in three versions with magnetic lengths of 2.4 m, 3.4 m, and 4.8 m. The quadrupoles feature a 56 mm aperture coil, designed on the basis of an 8.8 mm wide Rutherford-type NbTi cable for a nominal gradient of 200 T/m at 1.9 K and 5390 A. A total of 96 quadrupoles are in production in Tesla Engineering, UK. In this report we describe the construction of the pre-series MQM quadrupoles and present the results of the qualification tests.

3D LDV Measurements in Oscillatory Boundary Layers

Science.gov (United States)

Mier, J. M.; Garcia, M. H.

2012-12-01

The oscillatory boundary layer represents a particular case of unsteady wall-bounded flows in which fluid particles follow a periodic sinusoidal motion. Unlike steady boundary layer flows, the oscillatory flow regime and bed roughness character change in time along the period for every cycle, a characteristic that introduces a high degree of complexity in the analysis of these flows. Governing equations can be derived from the general Navier-Stokes equations for the motion of fluids, from which the exact solution for the laminar oscillatory boundary layer is obtained (also known as the 2nd Stokes problem). No exact solution exists for the turbulent case, thus, understanding of the main flow characteristics comes from experimental work. Several researchers have reported experimental work in oscillatory boundary layers since the 1960's; however, larger scale facilities and the development of newer measurement techniques with improved temporal and spatial resolution in recent years provides a unique opportunity to achieve a better understanding about this type of flows. Several experiments were performed in the Large Oscillatory Water and Sediment Tunnel (LOWST) facility at the Ven Te Chow Hydrosystems Laboratory, for a range of Reynolds wave numbers between 6x10^4 3D Laser Doppler Velocimetry (LDV) system was used to measure instantaneous flow velocities with a temporal resolution up to ~ 1,000 Hz. It was mounted on a 3-axis traverse with a spatial resolution of 0.01 mm in all three directions. The closest point to the bottom was measured at z = 0.2 mm (z+ ≈ 4), which allowed to capture boundary layer features with great detail. In order to achieve true 3D measurements, 2 probes were used on a perpendicular configuration, such that u and w components were measured from a probe on the side of the flume and v component was measured from a probe pointing down through and access window on top of the flume. The top probe was submerged in a water container, such that the

AA, wide quadrupole on measurement stand

CERN Multimedia

CERN PhotoLab

1981-01-01

Please look up 8101024 and 8103203 first. Wide quadrupole (QFW, QDW) with end-shims and shimming washers on the measurement stand. With the measurement coil one measured the harmonics of the magnetic field, determined the magnetic centre, and catalogued the effect of washer constellations.

Observation of a phononic quadrupole topological insulator

Science.gov (United States)

Serra-Garcia, Marc; Peri, Valerio; Süsstrunk, Roman; Bilal, Osama R.; Larsen, Tom; Villanueva, Luis Guillermo; Huber, Sebastian D.

2018-03-01

The modern theory of charge polarization in solids is based on a generalization of Berry’s phase. The possibility of the quantization of this phase arising from parallel transport in momentum space is essential to our understanding of systems with topological band structures. Although based on the concept of charge polarization, this same theory can also be used to characterize the Bloch bands of neutral bosonic systems such as photonic or phononic crystals. The theory of this quantized polarization has recently been extended from the dipole moment to higher multipole moments. In particular, a two-dimensional quantized quadrupole insulator is predicted to have gapped yet topological one-dimensional edge modes, which stabilize zero-dimensional in-gap corner states. However, such a state of matter has not previously been observed experimentally. Here we report measurements of a phononic quadrupole topological insulator. We experimentally characterize the bulk, edge and corner physics of a mechanical metamaterial (a material with tailored mechanical properties) and find the predicted gapped edge and in-gap corner states. We corroborate our findings by comparing the mechanical properties of a topologically non-trivial system to samples in other phases that are predicted by the quadrupole theory. These topological corner states are an important stepping stone to the experimental realization of topologically protected wave guides in higher dimensions, and thereby open up a new path for the design of metamaterials.

The effect of quadrupole force to the spectra of nuclei in the f7/2 shell

International Nuclear Information System (INIS)

Zhang Qingying

1992-01-01

The effect of quadrupole force on the spectra of nuclei in the f 7/2 shell is tested. The nuclear spectra are calculated by using the surface delta interaction plus quadrupole interaction and the modified surface delta interaction respectively. The results calculated with the former are much better than those with the latter, the role of the isospin modified term in the modified surface delta interaction can be substituted by the quadrupole interaction term. It is also shown that the effect of quadrupole interaction in the f 7/2 shell is important although the quadrupole deformations of nuclei in this region are not large

Nuclear quadrupole relaxation and viscosity in liquid metals

International Nuclear Information System (INIS)

Schirmacher, W.

1976-01-01

It is shown that the nuclear quadrupole relaxation rate due to the molecular motions in liquid metals is related to the shear and bulk viscosity and hence to the absorption coefficient of ultrasound. Application of the 'extended liquid phonon' model of Ortoleva and Nelkin - which is the third of a series of continued-fraction-approximations for the van Hove neutron scattering function - gives a relation to the self diffusion constant. The predictions of the theory concerning the temperature dependence are compared with quadrupole relaxation measurements of Riegel et al. and Kerlin et al. in liquid gallium. Agreement is found only with the data of Riegel et al. (orig.) [de

Low-frequency quadrupole impedance of undulators and wigglers

Directory of Open Access Journals (Sweden)

A. Blednykh

2016-10-01

Full Text Available An analytical expression of the low-frequency quadrupole impedance for undulators and wigglers is derived and benchmarked against beam-based impedance measurements done at the 3 GeV NSLS-II storage ring. The adopted theoretical model, valid for an arbitrary number of electromagnetic layers with parallel geometry, allows to calculate the quadrupole impedance for arbitrary values of the magnetic permeability μ_{r}. In the comparison of the analytical results with the measurements for variable magnet gaps, two limit cases of the permeability have been studied: the case of perfect magnets (μ_{r}→∞, and the case in which the magnets are fully saturated (μ_{r}=1.

Resting-State Oscillatory Activity in Autism Spectrum Disorders

Science.gov (United States)

Cornew, Lauren; Roberts, Timothy P. L.; Blaskey, Lisa; Edgar, J. Christopher

2012-01-01

Neural oscillatory anomalies in autism spectrum disorders (ASD) suggest an excitatory/inhibitory imbalance; however, the nature and clinical relevance of these anomalies are unclear. Whole-cortex magnetoencephalography data were collected while 50 children (27 with ASD, 23 controls) underwent an eyes-closed resting-state exam. A Fast Fourier…

Ellipsoidal universe can solve the cosmic microwave background quadrupole problem.

Science.gov (United States)

Campanelli, L; Cea, P; Tedesco, L

2006-09-29

The recent 3 yr Wilkinson Microwave Anisotropy Probe data have confirmed the anomaly concerning the low quadrupole amplitude compared to the best-fit Lambda-cold dark matter prediction. We show that by allowing the large-scale spatial geometry of our universe to be plane symmetric with eccentricity at decoupling or order 10(-2), the quadrupole amplitude can be drastically reduced without affecting higher multipoles of the angular power spectrum of the temperature anisotropy.

Disturbed oscillatory brain dynamics in subcortical ischemic vascular dementia

Directory of Open Access Journals (Sweden)

van Straaten Elisabeth CW

2012-07-01

Full Text Available Abstract Background White matter hyperintensities (WMH can lead to dementia but the underlying physiological mechanisms are unclear. We compared relative oscillatory power from electroencephalographic studies (EEGs of 17 patients with subcortical ischemic vascular dementia, based on extensive white matter hyperintensities (SIVD-WMH with 17 controls to investigate physiological changes underlying this diagnosis. Results Differences between the groups were large, with a decrease of relative power of fast activity in patients (alpha power 0.25 ± 0.12 versus 0.38 ± 0.13, p = 0.01; beta power 0.08 ± 0.04 versus 0.19 ± 0.07; p Conclusions This pattern of disturbance in oscillatory brain activity indicate loss of connections between neurons, providing a first step in the understanding of cognitive dysfunction in SIVD-WMH.

The evolution of a horizontal scale for oscillatory magnetoconvection

Energy Technology Data Exchange (ETDEWEB)

Murphy, J O [Monash Univ., Clayton (Australia). Dept. of Mathematics; Lopez, J M [Aeronautical Research Labs., Port Melbourne (Australia). Aerodynamics Div.

1989-01-01

Oscillatory convective motions have been observed in the umbrae of sunspots and, in the past, the linear theory of overstability has been used for sunspot models. Here a non-linear model for oscillatory convection has been used to investigate the possibility of a preferred horizontal cell size for these motions, in the presence of a magnetic field. The integration forward in time, from the conductive state, of the non-linear multimode equations governing magnetoconvection when the magnetic Prandtl number is less than one portrays a complex interaction between the evolving magnetic and vertical velocity horizontal scales. Preferred horizontal scales for the convective cells have been established by identifying the modes that substantially contribute to the overall convective heat transport. All other modes, although initially perturbed, in time essentially decay to zero through self interaction. 8 refs., 5 figs.

Quadrupole collective excitations in rapidly rotating nuclej

International Nuclear Information System (INIS)

Mikhajlov, I.N.

1983-01-01

The spectrum of collective quadrupole excitations in nuclei is investigated. The average nucleus field has the axial symmetry and rotation occurs relatively to this axis. Dependences of the spectrum of quadrupole oscillations on rotation rate for classic liquid drop (CLD) and for a drop of fermi-liquid (DFL) with fissionability parameter X=0.62 ( 154 Er) are presented. The dependence of probabilities of E2-transitions between single-phonon and phonon-free states on rotation rate for CLD and DFL with fussionability parameter X=0.62 ( 154 Er) is also presented. It is shown that for CLD collective E2-transition of states of yrast-consequence is absolutely forbidden. For DFL transitions are possible that lead to decay of phonon-free state with the excitation of phonons of γ-modes and decrease of angular momentum

Design of the CLIC Quadrupole Vacuum Chambers

CERN Document Server

Garion, C

2010-01-01

The Compact Linear Collider, under study, requires vacuum chambers with a very small aperture, of the order of 8 mm in diameter, and with a length up to around 2 m for the main beam quadrupoles. To keep the very tight geometrical tolerances on the quadrupoles, no bake out is allowed. The main issue is to reach UHV conditions (typically 10-9 mbar static pressure) in a system where the vacuum performance is driven by water outgassing. For this application, a thinwalled stainless steel vacuum chamber with two ante chambers equipped with NEG strips, is proposed. The mechanical design, especially the stability analysis, is shown. The key technologies of the prototype fabrication are given. Vacuum tests are carried out on the prototypes. The test set-up as well as the pumping system conditions are presented.

Unstable oscillatory Pierce modes of neutralized electron beams

International Nuclear Information System (INIS)

Cary, J.R.; Lemons, D.S.

1982-01-01

Oscillatory modes of the Pierce system have been calculated. These modes are found to have growth rates comparable to the previously investigated purely growing modes. When these modes are included, it is found that the Pierce system is unstable for most values of ω/sub p/ L/V 0 >π

Magnetic field in the end region of the SSC quadrupole magnet

International Nuclear Information System (INIS)

Caspi, S.; Helm, M.; Laslett, L.J.

1991-06-01

Recent advances in methods of computing magnetic fields have made it possible to study the field in the end region of the SS quadrupole magnet in detail. The placement of conductor in the straight section, away from the ends, was designed to produce a practically pure quadrupole field in the two-dimensional sense. The ends of the coils were designed to produce a practically pure quadrupole field in the integral sense using a method that ignores the presence of the iron yoke. Subsequently, the effect of presence of the yoke on the field was analyzed. The paper presents the end configuration together with the computed integrated multipole components, local multipole components, and local field components. A comparison with measurements is included. 5 refs., 5 figs., 1 tab

LES-based characterization of a suction and oscillatory blowing fluidic actuator

Science.gov (United States)

Kim, Jeonglae; Moin, Parviz

2015-11-01

Recently, a novel fluidic actuator using steady suction and oscillatory blowing was developed for control of turbulent flows. The suction and oscillatory blowing (SaOB) actuator combines steady suction and pulsed oscillatory blowing into a single device. The actuation is based upon a self-sustained mechanism of confined jets and does not require any moving parts. The control output is determined by a pressure source and the geometric details, and no additional input is needed. While its basic mechanisms have been investigated to some extent, detailed characteristics of internal turbulent flows are not well understood. In this study, internal flows of the SaOB actuator are simulated using large-eddy simulation (LES). Flow characteristics within the actuator are described in detail for a better understanding of the physical mechanisms and improving the actuator design. LES predicts the self-sustained oscillations of the turbulent jet. Switching frequency, maximum velocity at the actuator outlets, and wall pressure distribution are in good agreement with the experimental measurements. The computational results are used to develop simplified boundary conditions for numerical experiments of active flow control. Supported by the Boeing company.

Trapping of Electron Cloud LLC/Cesrta Quadrupole and Sextupole Magnets

International Nuclear Information System (INIS)

Wang, L.

2011-01-01

The Cornell Electron Storage Ring (CESR) has been reconfigured as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R and D (1). One of the primary goals of the CesrTA program is to investigate the interaction of the electron cloud with low emittance positron beam to explore methods to suppress the electron cloud, develop suitable advanced instrumentation required for these experimental studies and benchmark predictions by simulation codes. This paper reports the simulation of the electron-cloud formation in CESRTA and ILC quadrupole and sextupole magnets using the 3D code CLOUDLAND. We found that electrons can be trapped with a long lifetime in a quadrupole and sextupole magnet due to the mirror field trapping mechanism. We study the effects of magnet strength, bunch current, ante-chamber effect, bunch spacing effect and secondary emission yield (SEY) in great detail. The development of an electron cloud in magnets is the main concern where a weak solenoid field is not effective. Quadrupole and sextupole magnets have mirror field configurations which may trap electrons by the mirror field trapping mechanism (2). Fig.1 shows the orbit of a trapped electron in a quadrupole magnet. The electron makes gyration motion (called transverse motion) and also moves along the field line (called longitudinal motion). At the mirror point (middle of the field line), there is a maximum longitudinal energy and minimum transverse energy. When the electron moves away from the mirror point, its longitudinal energy reduces and the transverse energy increases as the magnetic field increases. If the magnetic field is strong enough, the longitudinal energy becomes zero at one point and then the electron is turned back by the strong field. Note that the electrons are trapped in the region near the middle of the field lines. Although all quadrupole and sextupole magnets can trap electrons in principle, the

Triple Quadrupole Versus High Resolution Quadrupole-Time-of-Flight Mass Spectrometry for Quantitative LC-MS/MS Analysis of 25-Hydroxyvitamin D in Human Serum

Science.gov (United States)

Geib, Timon; Sleno, Lekha; Hall, Rabea A.; Stokes, Caroline S.; Volmer, Dietrich A.

2016-08-01

We describe a systematic comparison of high and low resolution LC-MS/MS assays for quantification of 25-hydroxyvitamin D3 in human serum. Identical sample preparation, chromatography separations, electrospray ionization sources, precursor ion selection, and ion activation were used; the two assays differed only in the implemented final mass analyzer stage; viz. high resolution quadrupole-quadrupole-time-of-flight (QqTOF) versus low resolution triple quadrupole instruments. The results were assessed against measured concentration levels from a routine clinical chemiluminescence immunoassay. Isobaric interferences prevented the simple use of TOF-MS spectra for extraction of accurate masses and necessitated the application of collision-induced dissociation on the QqTOF platform. The two mass spectrometry assays provided very similar analytical figures of merit, reflecting the lack of relevant isobaric interferences in the MS/MS domain, and were successfully applied to determine the levels of 25-hydroxyvitamin D for patients with chronic liver disease.

Energies and transition probabilities from the full solution of nuclear quadrupole-octupole model

International Nuclear Information System (INIS)

Strecker, M.; Lenske, H.; Minkov, N.

2013-01-01

A collective model of nuclear quadrupole-octupole vibrations and rotations, originally restricted to a coherent interplay between quadrupole and octupole modes, is now developed for application beyond this restriction. The eigenvalue problem is solved by diagonalizing the unrestricted Hamiltonian in the basis of the analytic solution obtained in the case of the coherent-mode assumption. Within this scheme the yrast alternating-parity band is constructed by the lowest eigenvalues having the appropriate parity at given angular momentum. Additionally we include the calculation of transition probabilities which are fitted with the energies simultaneously. As a result we obtain a unique set of parameters. The obtained model parameters unambiguously determine the shape of the quadrupole-octupole potential. From the resulting wave functions quadrupole deformation expectation values are calculated which are found to be in agreement with experimental values. (author)

Isotopic dependence of the giant quadrupole resonance in the stable even-mass molybdenum nuclei

International Nuclear Information System (INIS)

Moalem, A.; Gaillard, Y.; Bemolle, A.M.; Buenerd, M.; Chauvin, J.; Duhamel, G.; Lebrun, D.; Martin, P.; Perrin, G.; de Saintignon, P.

1979-01-01

Inelastic scattering of 110 MeV 3 He particles is used to probe the quadrupole strength in the even Mo isotopes. The peak position of the giant quadrupole resonance is found to decrease more rapidly than predicted by the A/sup -1/3/ law, a behavior very similar to that exhibited by the photonuclear giant dipole resonance. The width and strength of the giant quadrupole resonance are practically constant in 92 Mo through 100 Mo

Design and construction of superconducting quadrupole magnets for ion beam fusion

International Nuclear Information System (INIS)

Wang, S.T.; Ludwig, H.; Turner, L.R.

1978-01-01

A high gradient superconducting quadrupole has been designed and developed as the heavy ion beam focussing element in the low velocity portions of an rf linac for the Argonne Ion Beam Fusion Reactor. The quadrupole magnets will require an extremely short magnet coil length (approximately 20 cm to 30 cm) and extremely high central gradients (approximately 100 T/m to 200 T/m). The useful warm bore will be about 4 to 6 cm and the integral gradient homogeneity should be constant to +-5% over the useful warm bore. Special techniques have been developed which are especially suitable for multilayer coil winding and coil assembly with high average current density over the coil cross section. A 5-layer quadrupole with 9 cm winding bore has been built and tested to the full performance of about 100 T/m with little training. The achieved average current density is 22,000 A/cm 2 at a peak field in conductor of about 5.0 T. An 8-layer quadrupole is under construction for a design gradient of 140 T/m over 9 cm winding bore. The peak field will be about 7.2 T

A superconducting quadrupole array for transport of multiple high current beams

International Nuclear Information System (INIS)

Faltens, A.; Shuman, D.

1999-01-01

We present a conceptual design of a superconducting quadrupole magnet array for the side-by-side transport of multiple high current particle beams in induction linear accelerators. The magnetic design uses a modified cosine 20 current distribution inside a square cell boundary. Each interior magnet's neighbors serve as the return flux paths and the poles are placed as close as possible to each other to facilitate this. No iron is present in the basic 2-D magnetic design; it will work at any current level without correction windings. Special 1/8th quadrupoles are used along the transverse periphery of the array to contain and channel flux back into the array, making every channel look as part of an infinite array. This design provides a fixed dimension array boundary equal to the quadrupole radius that can be used for arrays of any number of quadrupole channels, at any field level. More importantly, the design provides magnetic field separation between the array and the induction cores which may be surrounding it. Flux linkage between these two components can seriously affect the operation of both of them

Oscillatory behaviour of solutions of linear neutral differential ...

African Journals Online (AJOL)

The paper considers the contribution of space-time noise to the oscillatory behaviour of solutions of a linear neutral stochastic delay differential equation. It was established that under certain conditions on the time lags and their speed of adjustments, the presence of noise generates oscillation in the solution of the equation ...

Non-Steady Oscillatory Flow in Coarse Granular Materials

DEFF Research Database (Denmark)

Andersen, O. H.; Gent, M. R. A. van; Meer, J. W. van der

1992-01-01

Stationary and oscillatory flow through coarse granular materials have been investigated experimentally at Delft Hydraulics in their oscillating water tunnel with the objective of determining the coefficients of the extended Forchheimer equation. Cylinders, spheres and different types of rock have....... Further, for the non-stationary term, the virtual mass coefficient will be derived....

Superstrong Adjustable Permanent Magnet for a Linear Collider Final Focus

CERN Document Server

Iwashita, Y

2004-01-01

Super-strong permanent magnets are being considered as one of the candidates for the final focus quadrupole magnets in a linear collider. A short prototype with temperature compensation included and variable strength capability has been designed and fabricated. Fabrication details and some magnetic measurement results will be presented.

High Frequency Oscillatory Ventilation

Directory of Open Access Journals (Sweden)

AC Bryan

1996-01-01

Full Text Available High frequency oscillatory (HFO ventilation using low tidal volume and peak airway pressures is extremely efficient at eliminating carbon dioxide and raising pH in the newborn infant with acute respiratory failure. Improvement in oxygenation requires a strategy of sustained or repetitive inflations to 25 to 30 cm H2O in order to place the lung on the deflation limb of the pressure-volume curve. This strategy has also been shown to decrease the amount of secondary lung injury in animal models. Experience of the use of HFO ventilation as a rescue therapy as well as several published controlled trials have shown improved outcomes and a decrease in the use of extracorporeal membrane oxygenation when it has been used in newborns.

Conceptual design of a quadrupole magnet for eRHIC

Energy Technology Data Exchange (ETDEWEB)

Witte, H. [Brookhaven National Lab. (BNL), Upton, NY (United States); Berg, J. S. [Brookhaven National Lab. (BNL), Upton, NY (United States)

2015-05-03

eRHIC is a proposed upgrade to the existing Relativistic Heavy Ion Collider (RHIC) hadron facility at Brookhaven National Laboratory, which would allow collisions of up to 21 GeV polarized electrons with a variety of species from the existing RHIC accelerator. eRHIC employs an Energy Recovery Linac (ERL) and an FFAG lattice for the arcs. The arcs require open-midplane quadrupole magnets of up to 30 T/m gradient of good field quality. In this paper we explore initial quadrupole magnet design concepts based on permanent magnetic material which allow to modify the gradient during operation.

Launching focused surface plasmon in circular metallic grating

International Nuclear Information System (INIS)

Kumar, Pawan; Tripathi, V. K.; Kumar, Ashok; Shao, X.

2015-01-01

The excitation of focused surface plasma wave (SPW) over a metal–vacuum interface embedded with circular surface grating is investigated theoretically. The normally impinged radiation imparts oscillatory velocity to free electrons that beats with the surface ripple to produce a nonlinear current, driving the SPW. As SPW propagates, it gets focused. The focused radiation has a maximum at the centre of grating and decreases beyond the centre due to diffraction. The amplitude of SPW is fixed for a given groove depth and increases rapidly around the resonance frequency. The intensity at the focus point depends on dimensions of the grating. It increases with the radiation frequency approaching the surface plasmon resonance. The scheme has potential applications for photonic devices and surface enhanced Raman scattering

LARP Long Nb3Sn Quadrupole Design

International Nuclear Information System (INIS)

Ambrosio, G.; Andreev, N.; Anerella, M.; Barzi, E.; Bossert, R.; Caspi, S.; Chlachidize, G.; Dietderich, D.; Feher, S.; Ferracin, P.; Ghosh, A.; Hafalia, R.; Hannaford, R.; Kashikhin, V.V.; Kerby, J.; Lamm, M.; Lietzke, A.; McInturff, A.; Muratore, J.; Nobrega, F.; Novitsky, I.; Sabbi, G.L.; Schmalzle, J.; Tartaglia, M.; Turrioni, D.; Wanderer, P.; Whitson, G.; Zlobin, A.V.

2008-01-01

A major milestone for the LHC Accelerator Research Program (LARP) is the test, by the end of 2009, of two 4m-long quadrupole magnets (LQ) wound with Nb 3 Sn conductor. The goal of these magnets is to be a proof of principle that Nb 3 Sn is a viable technology for a possible LHC luminosity upgrade. The design of the LQ is based on the design of the LARP Technological Quadrupoles, presently under development at FNAL and LBNL, with 90-mm aperture and gradient higher than 200 T/m. The design of the first LQ model will be completed by the end of 2007 with the selection of a mechanical design. In this paper we present the coil design addressing some fabrication technology issues, the quench protection study, and three designs of the support structure

LARP Long Nb3Sn Quadrupole Design

International Nuclear Information System (INIS)

Ambrosio, G.; Andreev, N.; Anerella, M.; Barzi, E.; Bossert, R.; Caspi, S.; Chlachidize, G.; Dietderich, D.; Feher, S.; Felice, H.; Ferracin, P.; Fermilab; Brookhaven; LBL, Berkeley; Texas A-M

2007-01-01

A major milestone for the LHC Accelerator Research Program (LARP) is the test, by the end of 2009, of two 4m-long quadrupole magnets (LQ) wound with Nb3Sn conductor. The goal of these magnets is to be a proof of principle that Nb3Sn is a viable technology for a possible LHC luminosity upgrade. The design of the LQ is based on the design of the LARP Technological Quadrupoles, presently under development at FNAL and LBNL, with 90-mm aperture and gradient higher than 200 T/m. The design of the first LQ model will be completed by the end of 2007 with the selection of a mechanical design. In this paper we present the coil design addressing some fabrication technology issues, the quench protection study, and three designs of the support structure

LARP Long Nb3Sn Quadrupole Design

International Nuclear Information System (INIS)

Ambrosio, G.; Andreev, N.; Anerella, M.; Barzi, E.; Bossert, R.; Caspi, S.; Chlachidize, G.; Dietderich, D.; Feher, S.; Felice, H.; Ferracin, P.; Ghosh, A.; Hafalia, A.R.; Hannaford, C.R.; Kashikhin, V.V.; Kerby, J.; Lamm, M.; Lietzke, A.; McInturff, A.; Muratore, J.; Nobrega, F.; Novitsky, I.; Sabbi, G.L.; Schmalzle, J.; Tartaglia, M.; Turrioni, D.; Wanderer, P.; Whitson, G.; Zlobin, A.V.

2007-01-01

A major milestone for the LHC Accelerator Research Program (LARP) is the test, by the end of 2009, of two 4m-long quadrupole magnets (LQ) wound with Nb 3 Sn conductor. The goal of these magnets is to be a proof of principle that Nb 3 Sn is a viable technology for a possible LHC luminosity upgrade. The design of the LQ is based on the design of the LARP Technological Quadrupoles, presently under development at FNAL and LBNL, with 90-mm aperture and gradient higher than 200 T/m. The design of the first LQ model will be completed by the end of 2007 with the selection of a mechanical design. In this paper we present the coil design addressing some fabrication technology issues, the quench protection study, and three designs of the support structure

Quadrupole magnetic mapping of the high resolution spectrometers of Thomas Jefferson National Accelerator Laboratory, Hall A. (Q.M.M. project: Quadrupole Magnetic Measurement)

International Nuclear Information System (INIS)

Quemener, Gilles

1997-01-01

This thesis describes the magnetic measurements that have been performed on the superconducting quadrupoles of the High Resolution Spectrometers of TJNAF, Hall A (USA), which are designed to measure particle momentum up to 4 GeV.c -1 with a σp/p = 10 -4 resolution. The mapping method is based on rotating coil technique, the originality being a segmentation of the probe along the quad axis. Together with an accurate magnet modelling, the measurement of the flux variations through the set of rotating coils allows to determine the magnetic field at each point. We use the 3D field formalism, i.e., the Fourier-Bessel expansion of the field obtained by solving the Laplace equation. We describe the QMM method and then the apparatus consisting in two probes of length 1.6 m and 3.2 m built to map the three quadrupoles Q1, Q2, Q3. Data processing uses Fourier analysis. The mapping of the Electron Arm took place in situ in 1996. A first set of results concerns integral measurements including the properties of excitation cycle of the magnets (saturation and hysteresis). Second set of results in terms of local field yields the 3D field maps of the quadrupoles. After having applied corrections to the data we obtain a local field accuracy of 5 Gauss on each component, i.e. an uncertainty of 5.10 -4 relative to the quadrupole central field. We use SNAKE ray-tracing code with the implementation of QMM field maps and obtain preliminary results on HRS optics. (author)

Cellular and oscillatory substrates of fear extinction learning.

Science.gov (United States)

Davis, Patrick; Zaki, Yosif; Maguire, Jamie; Reijmers, Leon G

2017-11-01

The mammalian brain contains dedicated circuits for both the learned expression and suppression of fear. These circuits require precise coordination to facilitate the appropriate expression of fear behavior, but the mechanisms underlying this coordination remain unclear. Using a combination of chemogenetics, activity-based neuronal-ensemble labeling and in vivo electrophysiology, we found that fear extinction learning confers on parvalbumin-expressing (PV) interneurons in the basolateral amygdala (BLA) a dedicated role in the selective suppression of a previously encoded fear memory and BLA fear-encoding neurons. In addition, following extinction learning, PV interneurons enable a competing interaction between a 6-12 Hz oscillation and a fear-associated 3-6 Hz oscillation within the BLA. Loss of this competition increases a 3-6 Hz oscillatory signature, with BLA→medial prefrontal cortex directionality signaling the recurrence of fear expression. The discovery of cellular and oscillatory substrates of fear extinction learning that critically depend on BLA PV interneurons could inform therapies aimed at preventing the pathological recurrence of fear following extinction learning.

Stability of Armour Units in Oscillatory Flow

DEFF Research Database (Denmark)

Burcharth, Hans F.; Thompson, A. C.

Despite numerous breakwater model tests very little is known today about the various phenomena and parameters that determine the hydraulic stability characteristics of different types of armour. This is because separation of parameters is extremely difficult in traditional tests.With the object...... of separating some of the factors a deterministic test, in which horizontal beds of armour units were exposed to oscillatory flow, was performed in a pulsating water tunnel....

MQRAD, a computer code for synchrotron radiation from quadrupole magnets

International Nuclear Information System (INIS)

Morimoto, Teruhisa.

1984-01-01

The computer code, MQRAD, is developed for the calculation of the synchrotron radiation from the particles passing through quadrupole magnets at the straight section of the electron-positron colliding machine. This code computes the distributions of photon numbers and photon energies at any given points on the beam orbit. In this code, elements such as the quadrupole magnets and the drift spaces can be divided into many sub-elements in order to obtain the results with good accuracy. The synchrotron radiation produced by inserted quadrupole magnets at the interaction region of the electron-positron collider is one of the main background sources to the detector. The masking system against the synchrotron radiation at TRISTAN is very important because of the relatively high beam energy and the long straight section, which are 30 GeV and 100 meters, respectively. MQRAD has been used to design the masking system of the TOPAZ detector and the result is presented here as an example. (author)

The puzzle of the 6Li quadrupole moment: steps toward the solution

International Nuclear Information System (INIS)

Blokhintsev, L.D.; Kukulin, V.I.; Pomerantsev, V.N.

2005-01-01

The problem of origin of the ground-state 6 Li quadrupole deformation has been investigated with account of the three-deuteron component of this nucleus wave function. two long-standing puzzles related to the tensor interaction in 6 Li are known. The first one lies in the anomalously small value of the 6 Li quadrupole moment which, being negative, is in absolute magnitude smaller by the factor of 5 than that of 6 Li. The second puzzle consists in the anomalous behavior of the tensor analyzing power T 2q in scattering of polarized 6 Li nuclei from various targets. It is shown that the large (in absolute magnitude) negative contribution to the 6 Li quadrupole moment resulting from the three-deuteron configuration cancels almost completely the direct positive contribution due to the folding αd-potential. As a result, the total quadrupole moment turns out to be close to zero and highly sensitive to fine details of the tensor NN interaction and of the 4 He wave function [ru

Ab initio determination of the nuclear quadrupole moments of 114In, 115In, and 117In

International Nuclear Information System (INIS)

Errico, Leonardo A.; Renteria, Mario

2006-01-01

We present here ab initio determinations of the nuclear-quadrupole moment Q of hyperfine-probe-nuclear states of three different In isotopes: the 5 + 192 keV excited state of 114 In (probe for nuclear quadrupole alignment spectroscopy), the 9/2 + ground state of 115 In (nuclear magnetic and nuclear quadrupole resonance probe), and the 3/2 + 659 keV excited state of 117 In (perturbed angular correlations probe). These nuclear-quadrupole moments were determined by comparing experimental nuclear-quadrupole frequencies to the electric field gradient tensor calculated with high accuracy at In sites in metallic indium within the density functional theory. These ab initio calculations were performed with the full-potential linearized augmented plane wave method. The results obtained for the quadrupole moments of 114 In [Q( 114 In)=-0.14(1) b] are in clear discrepancy with those reported in the literature [Q( 114 In)=+0.16(6) b and +0.739(12) b]. For 115 In and 117 In our results are in excellent agreement with the literature and in the last case Q( 117 In) is determined with more precision. In the case of Q( 117 In), its sign cannot be determined because standard γ-γ perturbed angular correlations experiments are not sensitive to the sign of the nuclear-quadrupole frequency

Dark chocolate’s compositional effects revealed by oscillatory rheology

NARCIS (Netherlands)

van der Vaart, K.; Depypere, F.; De Graef, V.; Schall, P.; Fall, A.; Bonn, D.; Dewettinck, K.

2013-01-01

In this study, two types of oscillatory shear rheology are applied on dark chocolate with varying volume fraction, particle size distribution, and soy lecithin concentration. The first, a conventional strain sweep, allows for the separation of the elastic and viscous properties during the yielding.

Test Results of the LARP Nb$_3$Sn Quadrupole HQ03a

CERN Document Server

DiMarco, J; Anerella, M; Bajas, H; Chlachidze, G; Borgnolutti, F; Bossert, R; Cheng, D W; Dietderich, D; Felice, H; Pan, H; Ferracin, P; Ghosh, A; Godeke, A; Hafalia, A R; Marchevsky, M; Orris, D; Ravaioli, E; Sabbi, G; Salmi, T; Schmalzle, J; Stoynev, S; Strauss, T; Sylvester, C; Tartaglia, M; Todesco, E; Wanderer, P; Wang, X R; Yu, M

2016-01-01

The US LHC Accelerator Research Program (LARP) has been developing $Nb_3Sn$ quadrupoles of progressively increasing performance for the high luminosity upgrade of the Large Hadron Collider. The 120 mm aperture High-field Quadrupole (HQ) models are the last step in the R&D; phase supporting the development of the new IR Quadrupoles (MQXF). Three series of HQ coils were fabricated and assembled in a shell-based support structure, progressively optimizing the design and fabrication process. The final set of coils consistently applied the optimized design solutions, and was assembled in the HQ03a model. This paper reports a summary of the HQ03a test results, including training, mechanical performance, field quality and quench studies.

A simple mechanical system for studying adaptive oscillatory neural networks

DEFF Research Database (Denmark)

Jouffroy, Guillaume; Jouffroy, Jerome

Central Pattern Generators (CPG) are oscillatory systems that are responsible for generating rhythmic patterns at the origin of many biological activities such as for example locomotion or digestion. These systems are generally modelled as recurrent neural networks whose parameters are tuned so...... that the network oscillates in a suitable way, this tuning being a non trivial task. It also appears that the link with the physical body that these oscillatory entities control has a fundamental importance, and it seems that most bodies used for experimental validation in the literature (walking robots, lamprey...... a brief description of the Roller-Racer, we present as a preliminary study an RNN-based feed-forward controller whose parameters are obtained through the well-known teacher forcing learning algorithm, extended to learn signals with a continuous component....

Inertial confinement fusion driver enhancements: Final focusing systems and compact heavy-ion driver designs

International Nuclear Information System (INIS)

Bieri, R.L.

1991-01-01

Required elements of an inertial confinement fusion power plant are modeled and discussed. A detailed analysis of two critical elements of candidate drivers is done, and new component designs are proposed to increase the credibility and feasibility of each driver system. An analysis of neutron damage to the final elements of a laser focusing system is presented, and multilayer -- dielectric mirrors are shown to have damage lifetimes which axe too short to be useful in a commercial power plant. A new final-focusing system using grazing incidence metal mirrors to protect sensitive laser optics is designed and shown to be effective in extending the lifetime of the final focusing system. The reflectivities and damage limits of grazing incidence metal mirrors are examined in detail, and the required mirror sizes are shown to be compatible with the beam sizes and illumination geometries currently envisioned for laser drivers. A detailed design and analysis is also done for compact arrays of superconducting magnetic quadrupoles, which are needed in a multi-beam heavy-ion driver. The new array model is developed in more detail than some previous conceptual designs and models arrays which are more compact than arrays scaled from existing single -- quadrupole designs. The improved integrated model for compact arrays is used to compare the effects of various quadrupole array design choices on the size and cost of a heavy-ion driver. Array design choices which significantly affect the cost of a heavy-ion driver include the choice of superconducting material and the thickness of the collar used to support the winding stresses. The effect of these array design choices on driver size and cost is examined and the array model is used to estimate driver cost savings and performance improvements attainable with aggressive quadrupole array designs with high-performance superconductors

Oscillatory pulses and wave trains in a bistable reaction-diffusion system with cross diffusion.

Science.gov (United States)

Zemskov, Evgeny P; Tsyganov, Mikhail A; Horsthemke, Werner

2017-01-01

We study waves with exponentially decaying oscillatory tails in a reaction-diffusion system with linear cross diffusion. To be specific, we consider a piecewise linear approximation of the FitzHugh-Nagumo model, also known as the Bonhoeffer-van der Pol model. We focus on two types of traveling waves, namely solitary pulses that correspond to a homoclinic solution, and sequences of pulses or wave trains, i.e., a periodic solution. The effect of cross diffusion on wave profiles and speed of propagation is analyzed. We find the intriguing result that both pulses and wave trains occur in the bistable cross-diffusive FitzHugh-Nagumo system, whereas only fronts exist in the standard bistable system without cross diffusion.

Resolution limit of probe-forming systems with magnetic quadrupole lens triplets and quadruplets

International Nuclear Information System (INIS)

Ponomarev, A.G.; Melnik, K.I.; Miroshnichenko, V.I.; Storizhko, V.E.; Sulkio-Cleff, B.

2003-01-01

Over the past decade, in MeV ion beam microanalysis efforts to achieve a spatial resolution better than 0.1 μm with a beam current of ∼100 pA have been connected with microprobes of new generation where the probe is formed by means of separated magnetic quadrupole lens structures . However, as was pointed out in , no dramatic improvements in spatial resolution have been produced so far. For better understanding of the situation the authors carried out theoretical studies of multiparameter sets of probe-forming systems based on separated triplets and quadruplets of magnetic quadrupole lenses. Comparisons were made between the highest current values attained at different systems for a given beam spot size. The maximum parasitic sextupole and octupole field components were found whose contributions to spot broadening are tolerable. It is shown that the use of modern electrostatic accelerators and precision magnetic quadrupole lenses makes it possible to eliminate the effect of chromatic aberrations and second- and third-order parasitic aberrations resulting from distortions of the quadrupole lens symmetry. Therefore probe-forming systems with triplets and quadruplets of magnetic quadrupole lenses have a lower theoretical spatial resolution limit which is restricted mainly by intrinsic spherical third-order aberrations in state-of-the-art microprobes

Effect of sp3-hybridized defects on the oscillatory behavior of carbon nanotube oscillators

International Nuclear Information System (INIS)

Guo, Taiyu; Ding, Tony Weixi; Pei, Qing-Xiang; Zhang, Yong-Wei

2011-01-01

Using molecular dynamics simulations, we investigate the oscillatory behaviors of carbon nanotube oscillators containing sp 3 -hybridized defects formed by hydrogen chemisorption. It is found that the presence of these defects significantly affects the kinetic and potential energies of the nanotube systems, which in turn affects their oscillation periods and frequencies. We have also studied the oscillatory characteristics of the oscillators containing sp 3 -hybridized Stone-Wales defects. Our results show that it is possible to control the motion of the inner nanotube by introducing sp 3 -hybridized defects on the outer nanotube, which provides a potential way to tune the oscillatory behavior of nanotube oscillators. -- Highlights: → sp 3 -hybridized defects increase energy dissipation. → sp 3 -hybridized defects arranged in a row have stronger effect than that in a ring. → sp 3 -hybridized defects reduces the effect of SW defects.

Global set of quadrupole deformation parameters for even-even nuclei

International Nuclear Information System (INIS)

Raman, S.; Nestor, C.W. Jr.

1986-01-01

A compilation of experimental results has been completed for the reduced electric quadrupole transition probability [B(E2)up arrow] between the 0 + ground state and the first 2 + state in even-even nuclei. This compilation together with certain simple relationships noted by other authors can be used to make reasonable predictions of unmeasured B(E2)up arrow values. The quadrupole deformation parameter β 2 immediately follows, because β 2 is proportional to [B(E2)up arrow]/sup 1/2/. 8 refs., 7 figs

Oscillatory regime in the multidimensional homogeneous cosmological models induced by a vector field

International Nuclear Information System (INIS)

Benini, R; Kirillov, A A; Montani, Giovanni

2005-01-01

We show that in multidimensional gravity, vector fields completely determine the structure and properties of singularity. It turns out that in the presence of a vector field the oscillatory regime exists in all spatial dimensions and for all homogeneous models. By analysing the Hamiltonian equations we derive the Poincare return map associated with the Kasner indexes and fix the rules according to which the Kasner vectors rotate. In correspondence to a four-dimensional spacetime, the oscillatory regime here constructed overlaps the usual Belinski-Khalatnikov-Liftshitz one

rf quadrupole linac: a new low-energy accelerator

International Nuclear Information System (INIS)

Hamm, R.W.; Crandall, K.R.; Fuller, C.W.

1980-01-01

A new concept in low-energy particle accelerators, the radio-frequency quadrupole (RFQ) linac, is currently being developed at the Los Alamos National Scientific Laboratory. In this new linear accelerating structure both the focusing and accelerating forces are produced by the rf fields. It can accept a high-current, low-velocity dc ion beam and bunch it with a high capture efficiency. The performance of this structure as a low-energy linear accelerator has been verified with the successful construction of a proton RFQ linac. This test structure has accelerated 38 mA of protons from 100 keV to 640 keV in 1.1 meters with a capture efficiency greater than 80%. In this paper a general description of the RFQ linac and an outline of the basic RFQ linac design procedure are presented in addition to the experimental results from the test accelerator. Finally, several applications of this new accelerator are discussed

Synchronization enhancement via an oscillatory bath in a network of ...

Indian Academy of Sciences (India)

2015-02-05

Feb 5, 2015 ... 2Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA ... The robustness of synchronization strategy is tested using a local and global ..... enhancement effect that the oscillatory bath has in the ...

Design optimization of the International Linear Collider Final Focus System with a long L*

CERN Document Server

Plassard, Fabien

This Master's Thesis work has been done in the Aerospace Engineering master's programme framework and carried out at the European Organization for Nuclear Research (CERN). It was conducted under the 500 GeV e-e+ International Linear Collider (ILC) study and focused on the design and performance optimization of the Final Focus System (FFS). The purpose of the final focus system of the future linear colliders (ILC and CLIC) is to demagnify the beam to the required transverse size at the interaction point (IP). The FFS is designed for a flat-beam in a compact way based on a local chromaticity correction which corrects both horizontal and vertical chromaticities simultaneously. An alternative FFS configuration based on the traditional scheme with two dedicated chromatic correction sections for horizontal and vertical chromaticities and a long L * option has been developed. A longer free space between the last quadrupole and the IP allows to place the last quadrupole on a stable ground, with fewer engineering ...

Oscillatory Critical Amplitudes in Hierarchical Models and the Harris Function of Branching Processes

Science.gov (United States)

Costin, Ovidiu; Giacomin, Giambattista

2013-02-01

Oscillatory critical amplitudes have been repeatedly observed in hierarchical models and, in the cases that have been taken into consideration, these oscillations are so small to be hardly detectable. Hierarchical models are tightly related to iteration of maps and, in fact, very similar phenomena have been repeatedly reported in many fields of mathematics, like combinatorial evaluations and discrete branching processes. It is precisely in the context of branching processes with bounded off-spring that T. Harris, in 1948, first set forth the possibility that the logarithm of the moment generating function of the rescaled population size, in the super-critical regime, does not grow near infinity as a power, but it has an oscillatory prefactor (the Harris function). These oscillations have been observed numerically only much later and, while the origin is clearly tied to the discrete character of the iteration, the amplitude size is not so well understood. The purpose of this note is to reconsider the issue for hierarchical models and in what is arguably the most elementary setting—the pinning model—that actually just boils down to iteration of polynomial maps (and, notably, quadratic maps). In this note we show that the oscillatory critical amplitude for pinning models and the Harris function coincide. Moreover we make explicit the link between these oscillatory functions and the geometry of the Julia set of the map, making thus rigorous and quantitative some ideas set forth in Derrida et al. (Commun. Math. Phys. 94:115-132, 1984).

Nuclear quadrupole moment of the 99Tc ground state

International Nuclear Information System (INIS)

Errico, Leonardo; Darriba, German; Renteria, Mario; Tang Zhengning; Emmerich, Heike; Cottenier, Stefaan

2008-01-01

By combining first-principles calculations and existing nuclear magnetic resonance (NMR) experiments, we determine the quadrupole moment of the 9/2 + ground state of 99 Tc to be (-)0.14(3)b. This confirms the value of -0.129(20)b, which is currently believed to be the most reliable experimental determination, and disagrees with two earlier experimental values. We supply ab initio calculated electric-field gradients for Tc in YTc 2 and ZrTc 2 . If this calculated information would be combined with yet to be performed Tc-NMR experiments in these compounds, the error bar on the 99 Tc ground state quadrupole moment could be further reduced

Characterization and tuning of ultrahigh gradient permanent magnet quadrupoles

Directory of Open Access Journals (Sweden)

S. Becker

2009-10-01

Full Text Available The application of quadrupole devices with high field gradients and small apertures requires precise control over higher order multipole field components. We present a new scheme for performance control and tuning, which allows the illumination of most of the quadrupole device aperture because of the reduction of higher order field components. Consequently, the size of the aperture can be minimized to match the beam size achieving field gradients of up to 500  T m^{-1} at good imaging quality. The characterization method based on a Hall probe measurement and a Fourier analysis was confirmed using the high quality electron beam at the Mainz Microtron MAMI.

Nb3Sn Quadrupoles Designs For The LHC Upgrades

International Nuclear Information System (INIS)

Felice, Helene

2008-01-01

In preparation for the LHC luminosity upgrades, high field and large aperture Nb 3 Sn quadrupoles are being studied. This development has to incorporate all the relevant features for an accelerator magnet like alignment and cooling channels. The LARP HQ model is a high field and large bore quadrupole that will meet these requirements. The 2-layer coils are surrounded by a structure based on key and bladder technology with supporting iron yoke and aluminum shell. This structure is aimed at pre-stress control, alignment and field quality. We present here the magnetic and mechanical design of HQ, along with recent progress on the development of the first 1-meter model.

Velocity damper for electromagnetically levitated materials

Science.gov (United States)

Fox, R.J.

1994-06-07

A system for damping oscillatory and spinning motions induced in an electromagnetically levitated material is disclosed. Two opposed field magnets are located orthogonally to the existing levitation coils for providing a DC quadrupole field (cusp field) around the material. The material used for generating the DC quadrupole field must be nonconducting to avoid eddy-current heating and of low magnetic permeability to avoid distorting the induction fields providing the levitation. 1 fig.

ANALYTICAL SOLUTIONS OF SINGULAR ISOTHERMAL QUADRUPOLE LENS

International Nuclear Information System (INIS)

Chu Zhe; Lin, W. P.; Yang Xiaofeng

2013-01-01

Using an analytical method, we study the singular isothermal quadrupole (SIQ) lens system, which is the simplest lens model that can produce four images. In this case, the radial mass distribution is in accord with the profile of the singular isothermal sphere lens, and the tangential distribution is given by adding a quadrupole on the monopole component. The basic properties of the SIQ lens have been studied in this Letter, including the deflection potential, deflection angle, magnification, critical curve, caustic, pseudo-caustic, and transition locus. Analytical solutions of the image positions and magnifications for the source on axes are derived. We find that naked cusps will appear when the relative intensity k of quadrupole to monopole is larger than 0.6. According to the magnification invariant theory of the SIQ lens, the sum of the signed magnifications of the four images should be equal to unity, as found by Dalal. However, if a source lies in the naked cusp, the summed magnification of the left three images is smaller than the invariant 1. With this simple lens system, we study the situations where a point source infinitely approaches a cusp or a fold. The sum of the magnifications of the cusp image triplet is usually not equal to 0, and it is usually positive for major cusps while negative for minor cusps. Similarly, the sum of magnifications of the fold image pair is usually not equal to 0 either. Nevertheless, the cusp and fold relations are still equal to 0 in that the sum values are divided by infinite absolute magnifications by definition.

Electrons in a positive-ion beam with solenoid or quadrupole magnetic transport

International Nuclear Information System (INIS)

Molvik, A.W.; Kireeff Covo, M.; Cohen, R.; Coleman, J.; Sharp, W.; Bieniosek, F.; Friedman, A.; Roy, P.K.; Seidl, P.; Lund, S.M.; Faltens, A.; Vay, J.L.; Prost, L.

2007-01-01

The High Current Experiment (HCX) is used to study beam transport and accumulation of electrons in quadrupole magnets and the Neutralized Drift-Compression Experiment (NDCX) to study beam transport through and accumulation of electrons in magnetic solenoids. We find that both clearing and suppressor electrodes perform as intended, enabling electron cloud densities to be minimized. Then, the measured beam envelopes in both quadrupoles and solenoids agree with simulations, indicating that theoretical beam current transport limits are reliable, in the absence of electrons. At the other extreme, reversing electrode biases with the solenoid transport effectively traps electrons; or, in quadrupole magnets, grounding the suppressor electrode allows electron emission from the end wall to flood the beam, in both cases producing significant degradation in the beam

Oscillatory lower body negative pressure impairs working memory task-related functional hyperemia in healthy volunteers.

Science.gov (United States)

Merchant, Sana; Medow, Marvin S; Visintainer, Paul; Terilli, Courtney; Stewart, Julian M

2017-04-01

Neurovascular coupling (NVC) describes the link between an increase in task-related neural activity and increased cerebral blood flow denoted "functional hyperemia." We previously showed induced cerebral blood flow oscillations suppressed functional hyperemia; conversely functional hyperemia also suppressed cerebral blood flow oscillations. We used lower body negative pressure (OLBNP) oscillations to force oscillations in middle cerebral artery cerebral blood flow velocity (CBFv). Here, we used N-back testing, an intellectual memory challenge as a neural activation task, to test the hypothesis that OLBNP-induced oscillatory cerebral blood flow can reduce functional hyperemia and NVC produced by a working memory task and can interfere with working memory. We used OLBNP (-30 mmHg) at 0.03, 0.05, and 0.10 Hz and measured spectral power of CBFv at all frequencies. Neither OLBNP nor N-back, alone or combined, affected hemodynamic parameters. 2-Back power and OLBNP individually were compared with 2-back power during OLBNP. 2-Back alone produced a narrow band increase in oscillatory arterial pressure (OAP) and oscillatory cerebral blood flow power centered at 0.0083 Hz. Functional hyperemia in response to 2-back was reduced to near baseline and 2-back memory performance was decreased by 0.03-, 0.05-, and 0.10-Hz OLBNP. OLBNP alone produced increased oscillatory power at frequencies of oscillation not suppressed by added 2-back. However, 2-back preceding OLBNP suppressed OLBNP power. OLBNP-driven oscillatory CBFv blunts NVC and memory performance, while memory task reciprocally interfered with forced CBFv oscillations. This shows that induced cerebral blood flow oscillations suppress functional hyperemia and functional hyperemia suppresses cerebral blood flow oscillations. NEW & NOTEWORTHY We show that induced cerebral blood flow oscillations suppress functional hyperemia produced by a working memory task as well as memory task performance. We conclude that oscillatory

Measurement of time dependent fields in high gradient superconducting quadrupoles for the Tevatron

International Nuclear Information System (INIS)

Lamm, M.J.; Coulter, K.; Gourlay, S.; Jaffery, T.S.

1990-10-01

Magnetic field measurements have been performed on prototype and production magnets from two high gradient superconducting quadrupoles designs. One design is a double shell quadrupole with 36 strand Rutherford cable. The other design is a single shell quadrupole with 5 individually monolithic strands connected in series. These magnets have similar bore diameters and cable dimensions. However, there are significant differences between the two designs, as well as differences between prototype and production magnets within each design, with regard to Cu to superconductor ratio, filament diameter and filament spacing to strand diameter. The time dependence of fixed currents of the measured magnetic fields is discussed. 9 refs., 6 figs., 1 tab

Recent developments in structure-preserving algorithms for oscillatory differential equations

CERN Document Server

Wu, Xinyuan

2018-01-01

The main theme of this book is recent progress in structure-preserving algorithms for solving initial value problems of oscillatory differential equations arising in a variety of research areas, such as astronomy, theoretical physics, electronics, quantum mechanics and engineering. It systematically describes the latest advances in the development of structure-preserving integrators for oscillatory differential equations, such as structure-preserving exponential integrators, functionally fitted energy-preserving integrators, exponential Fourier collocation methods, trigonometric collocation methods, and symmetric and arbitrarily high-order time-stepping methods. Most of the material presented here is drawn from the recent literature. Theoretical analysis of the newly developed schemes shows their advantages in the context of structure preservation. All the new methods introduced in this book are proven to be highly effective compared with the well-known codes in the scientific literature. This book also addre...

Role of synchronized oscillatory brain activity for human pain perception.

Science.gov (United States)

Hauck, Michael; Lorenz, Jürgen; Engel, Andreas K

2008-01-01

The understanding of cortical pain processing in humans has significantly improved since the development of modern neuroimaging techniques. Non-invasive electrophysiological approaches such as electro- and magnetoencephalography have proven to be helpful tools for the real-time investigation of neuronal signals and synchronous communication between cortical areas. In particular, time-frequency decomposition of signals recorded with these techniques seems to be a promising approach because different pain-related oscillatory changes can be observed within different frequency bands, which are likely to be linked to specific sensory and motor functions. In this review we discuss the latest evidence on pain-induced time-frequency signals and propose that changes in oscillatory activity reflect an essential communication mechanism in the brain that is modulated during pain processing. The importance of synchronization processes for normal and pathological pain processing, such as chronic pain states, is discussed.

The effect of a laser beam displacement on parametric oscillatory instabilities for Advanced LIGO

International Nuclear Information System (INIS)

Heinert, D.; Strigin, S.E.

2011-01-01

The arm cavities of real gravitational wave detectors can show small deviations like a tilt or a spatial shift between the cavity mirrors. These deviations lead to a separation of the optical mode centres with respect to the mirror's centre. In this Letter we perform the computation of parametric instable modes considering the described displacement. We further analyse the possibility of parametric oscillatory instability in the Advanced LIGO interferometer for the case of a displaced arm cavity. Our results reveal an additional number of optical and elastic mode combinations due to a displacement that can give rise to the undesirable effect of parametric oscillatory instability. -- Highlights: → We analyse the possibility of parametric oscillatory instability in the Advanced LIGO interferometer. → We perform the computation of parametric instable modes considering the mirror displacement. → Our results reveal an additional number of optical and elastic mode unstable combinations.

Structural state diagram of concentrated suspensions of jammed soft particles in oscillatory shear flow

Science.gov (United States)

Khabaz, Fardin; Cloitre, Michel; Bonnecaze, Roger T.

2018-03-01

In a recent study [Khabaz et al., Phys. Rev. Fluids 2, 093301 (2017), 10.1103/PhysRevFluids.2.093301], we showed that jammed soft particle glasses (SPGs) crystallize and order in steady shear flow. Here we investigate the rheology and microstructures of these suspensions in oscillatory shear flow using particle-dynamics simulations. The microstructures in both types of flows are similar, but their evolutions are very different. In both cases the monodisperse and polydisperse suspensions form crystalline and layered structures, respectively, at high shear rates. The crystals obtained in the oscillatory shear flow show fewer defects compared to those in the steady shear. SPGs remain glassy for maximum oscillatory strains less than about the yield strain of the material. For maximum strains greater than the yield strain, microstructural and rheological transitions occur for SPGs. Polydisperse SPGs rearrange into a layered structure parallel to the flow-vorticity plane for sufficiently high maximum shear rates and maximum strains about 10 times greater than the yield strain. Monodisperse suspensions form a face-centered cubic (FCC) structure when the maximum shear rate is low and hexagonal close-packed (HCP) structure when the maximum shear rate is high. In steady shear, the transition from a glassy state to a layered one for polydisperse suspensions included a significant induction strain before the transformation. In oscillatory shear, the transformation begins to occur immediately and with different microstructural changes. A state diagram for suspensions in large amplitude oscillatory shear flow is found to be in close but not exact agreement with the state diagram for steady shear flow. For more modest amplitudes of around one to five times the yield strain, there is a transition from a glassy structure to FCC and HCP crystals, at low and high frequencies, respectively, for monodisperse suspensions. At moderate frequencies, the transition is from glassy to HCP via

Stabilization of the Electron-Nuclear Spin Orientation in Quantum Dots by the Nuclear Quadrupole Interaction

Science.gov (United States)

Dzhioev, R. I.; Korenev, V. L.

2007-07-01

The nuclear quadrupole interaction eliminates the restrictions imposed by hyperfine interaction on the spin coherence of an electron and nuclei in a quantum dot. The strain-induced nuclear quadrupole interaction suppresses the nuclear spin flip and makes possible the zero-field dynamic nuclear polarization in self-organized InP/InGaP quantum dots. The direction of the effective nuclear magnetic field is fixed in space, thus quenching the magnetic depolarization of the electron spin in the quantum dot. The quadrupole interaction suppresses the zero-field electron spin decoherence also for the case of nonpolarized nuclei. These results provide a new vision of the role of the nuclear quadrupole interaction in nanostructures: it elongates the spin memory of the electron-nuclear system.

Theoretical analysis of oscillatory terms in lattice heat-current time correlation functions and their contributions to thermal conductivity

Science.gov (United States)

Pereverzev, Andrey; Sewell, Tommy

2018-03-01

Lattice heat-current time correlation functions for insulators and semiconductors obtained using molecular dynamics (MD) simulations exhibit features of both pure exponential decay and oscillatory-exponential decay. For some materials the oscillatory terms contribute significantly to the lattice heat conductivity calculated from the correlation functions. However, the origin of the oscillatory terms is not well understood, and their contribution to the heat conductivity is accounted for by fitting them to empirical functions. Here, a translationally invariant expression for the heat current in terms of creation and annihilation operators is derived. By using this full phonon-picture definition of the heat current and applying the relaxation-time approximation we explain, at least in part, the origin of the oscillatory terms in the lattice heat-current correlation function. We discuss the relationship between the crystal Hamiltonian and the magnitude of the oscillatory terms. A solvable one-dimensional model is used to illustrate the potential importance of terms that are omitted in the commonly used phonon-picture expression for the heat current. While the derivations are fully quantum mechanical, classical-limit expressions are provided that enable direct contact with classical quantities obtainable from MD.

Oscillatory Reinstatement Enhances Declarative Memory.

Science.gov (United States)

Javadi, Amir-Homayoun; Glen, James C; Halkiopoulos, Sara; Schulz, Mei; Spiers, Hugo J

2017-10-11

Declarative memory recall is thought to involve the reinstatement of neural activity patterns that occurred previously during encoding. Consistent with this view, greater similarity between patterns of activity recorded during encoding and retrieval has been found to predict better memory performance in a number of studies. Recent models have argued that neural oscillations may be crucial to reinstatement for successful memory retrieval. However, to date, no causal evidence has been provided to support this theory, nor has the impact of oscillatory electrical brain stimulation during encoding and retrieval been assessed. To explore this we used transcranial alternating current stimulation over the left dorsolateral prefrontal cortex of human participants [ n = 70, 45 females; age mean (SD) = 22.12 (2.16)] during a declarative memory task. Participants received either the same frequency during encoding and retrieval (60-60 or 90-90 Hz) or different frequencies (60-90 or 90-60 Hz). When frequencies matched there was a significant memory improvement (at both 60 and 90 Hz) relative to sham stimulation. No improvement occurred when frequencies mismatched. Our results provide support for the role of oscillatory reinstatement in memory retrieval. SIGNIFICANCE STATEMENT Recent neurobiological models of memory have argued that large-scale neural oscillations are reinstated to support successful memory retrieval. Here we used transcranial alternating current stimulation (tACS) to test these models. tACS has recently been shown to induce neural oscillations at the frequency stimulated. We stimulated over the left dorsolateral prefrontal cortex during a declarative memory task involving learning a set of words. We found that tACS applied at the same frequency during encoding and retrieval enhances memory. We also find no difference between the two applied frequencies. Thus our results are consistent with the proposal that reinstatement of neural oscillations during retrieval

Oscillatory serotonin function in depression.

Science.gov (United States)

Salomon, Ronald M; Cowan, Ronald L

2013-11-01

Oscillations in brain activities with periods of minutes to hours may be critical for normal mood behaviors. Ultradian (faster than circadian) rhythms of mood behaviors and associated central nervous system activities are altered in depression. Recent data suggest that ultradian rhythms in serotonin (5HT) function also change in depression. In two separate studies, 5HT metabolites in cerebrospinal fluid (CSF) were measured every 10 min for 24 h before and after chronic antidepressant treatment. Antidepressant treatments were associated with enhanced ultradian amplitudes of CSF metabolite levels. Another study used resting-state functional magnetic resonance imaging (fMRI) to measure amplitudes of dorsal raphé activation cycles following sham or active dietary depletions of the 5HT precursor (tryptophan). During depletion, amplitudes of dorsal raphé activation cycles increased with rapid 6 s periods (about 0.18 Hz) while functional connectivity weakened between dorsal raphé and thalamus at slower periods of 20 s (0.05 Hz). A third approach studied MDMA (ecstasy, 3,4-methylenedioxy-N-methylamphetamine) users because of their chronically diminished 5HT function compared with non-MDMA polysubstance users (Karageorgiou et al., 2009). Compared with a non-MDMA using cohort, MDMA users showed diminished fMRI intra-regional coherence in motor regions along with altered functional connectivity, again suggesting effects of altered 5HT oscillatory function. These data support a hypothesis that qualities of ultradian oscillations in 5HT function may critically influence moods and behaviors. Dysfunctional 5HT rhythms in depression may be a common endpoint and biomarker for depression, linking dysfunction of slow brain network oscillators to 5HT mechanisms affected by commonly available treatments. 5HT oscillatory dysfunction may define illness subtypes and predict responses to serotonergic agents. Further studies of 5HT oscillations in depression are indicated. Copyright �

On the effect of a longitudinal magnetic field on oscillatory ...

Indian Academy of Sciences (India)

. The frequency, ... dinal magnetic field on the oscillatory characteristics of a subnormal region it is proposed to study the variation of ... earth to provide a signal to the oscilloscope (60 MHz digital storage, PM 3350, Phillips). A current meter ...

Reflood modeling under oscillatory flow conditions with Cathare

International Nuclear Information System (INIS)

Kelly, J.M.; Bartak, J.; Janicot, A.

1993-01-01

The problems and the current status in oscillatory reflood modelling with the CATHARE code are presented. The physical models used in CATHARE for reflood modelling predicted globally very well the forced reflood experiments. Significant drawbacks existed in predicting experiments with oscillatory flow (both forced and gravity driven). First, the more simple case of forced flow oscillations was analyzed. Modelling improvements within the reflooding package resolved the problem of quench front blockages and unphysical oscillations. Good agreements with experiment for the ERSEC forced oscillations reflood tests is now obtained. For gravity driven reflood, CATHARE predicted sustained flow oscillations during 100-150 s after the start of the reflood, whereas in the experiment flow oscillations were observed only during 25-30 s. Possible areas of modeling improvements are identified and several new correlations are suggested. The first test calculations of the BETHSY test 6.7A4 have shown that the oscillations are mostly sensitive to heat flux modeling downstream of the quench front. A much better agreement between CATHARE results and the experiment was obtained. However, further effort is necessary to obtain globally satisfactory predictions of gravity driven system reflood tests. (authors) 6 figs., 35 refs

A learning algorithm for oscillatory cellular neural networks.

Science.gov (United States)

Ho, C Y.; Kurokawa, H

1999-07-01

We present a cellular type oscillatory neural network for temporal segregation of stationary input patterns. The model comprises an array of locally connected neural oscillators with connections limited to a 4-connected neighborhood. The architecture is reminiscent of the well-known cellular neural network that consists of local connection for feature extraction. By means of a novel learning rule and an initialization scheme, global synchronization can be accomplished without incurring any erroneous synchrony among uncorrelated objects. Each oscillator comprises two mutually coupled neurons, and neurons share a piecewise-linear activation function characteristic. The dynamics of traditional oscillatory models is simplified by using only one plastic synapse, and the overall complexity for hardware implementation is reduced. Based on the connectedness of image segments, it is shown that global synchronization and desynchronization can be achieved by means of locally connected synapses, and this opens up a tremendous application potential for the proposed architecture. Furthermore, by using special grouping synapses it is demonstrated that temporal segregation of overlapping gray-level and color segments can also be achieved. Finally, simulation results show that the learning rule proposed circumvents the problem of component mismatches, and hence facilitates a large-scale integration.

Reflood modeling under oscillatory flow conditions with Cathare

Energy Technology Data Exchange (ETDEWEB)

Kelly, J M; Bartak, J; Janicot, A

1994-12-31

The problems and the current status in oscillatory reflood modelling with the CATHARE code are presented. The physical models used in CATHARE for reflood modelling predicted globally very well the forced reflood experiments. Significant drawbacks existed in predicting experiments with oscillatory flow (both forced and gravity driven). First, the more simple case of forced flow oscillations was analyzed. Modelling improvements within the reflooding package resolved the problem of quench front blockages and unphysical oscillations. Good agreements with experiment for the ERSEC forced oscillations reflood tests is now obtained. For gravity driven reflood, CATHARE predicted sustained flow oscillations during 100-150 s after the start of the reflood, whereas in the experiment flow oscillations were observed only during 25-30 s. Possible areas of modeling improvements are identified and several new correlations are suggested. The first test calculations of the BETHSY test 6.7A4 have shown that the oscillations are mostly sensitive to heat flux modeling downstream of the quench front. A much better agreement between CATHARE results and the experiment was obtained. However, further effort is necessary to obtain globally satisfactory predictions of gravity driven system reflood tests. (authors) 6 figs., 35 refs.

The LHC Main Quadrupoles during Series Fabrication

CERN Document Server

Tortschanoff, Theodor; Durante, M; Hagen, P; Klein, U; Krischel, D; Payn, A; Rossi, L; Schellong, B; Schmidt, P; Simon, F; Schirm, K-M; Todesco, E

2006-01-01

By the end of August 2005 about 320 of the 400 main LHC quadrupole magnets have been fabricated and about 220 of them assembled into their cold masses, together with corrector magnets. About 130 of them have been cold tested in their cryostats and most of the quadrupoles exceeded their nominal excitation, i.e. 12,000 A, after no more than two training quenches. During this series fabrication, the quality of the magnets and cold masses was thoroughly monitored by means of warm magnetic field measurements, of strict geometrical checking, and of various electrical verifications. A number of modifications were introduced in order to improve the magnet fabrication, mainly correction of the coil geometry for achieving the specified field quality and measures for avoiding coil insulation problems. Further changes concern the electrical connectivity and insulation of instrumentation, and of the corrector magnets inside the cold masses. The contact resistances for the bus-bar connections to the quench protection diode...

Manufacturing experience for the LHC inner triplet quadrupole cables

CERN Document Server

Scanlan, R M; Bossert, R; Kerby, J S; Ghosh, A K; Boivin, M; Roy, T

2002-01-01

The design for the U.S. LHC Inner Triplet Quadrupole magnet requires a 37 strand (inner layer) and a 46 strand (outer layer) cable. This represents the largest number of strands attempted to date for a production quantity of Rutherford-type cable. The cable parameters were optimized during the production of a series of short prototype magnets produced at FNAL. These optimization studies focused on critical current degradation, dimensional control, coil winding, and interstrand resistance. After the R&D phase was complete, the technology was transferred to NEEW and a new cabling machine was installed to produce these cables. At present, about 60 unit lengths, out of 90 required for the entire production series of magnets, have been completed for each type of cable. The manufacturing experience with these challenging cables will be reported. Finally, the implications for even larger cables, with more strands, will be discussed. (8 refs).

Charged-particle magnetic-quadrupole spectrometer for neutron induced reactions

International Nuclear Information System (INIS)

Haight, R.C.; Grimes, S.M.; Tuckey, B.J.; Anderson, J.D.

1975-01-01

A spectrometer has been developed for measuring the charged particle production cross sections and spectra in neutron-induced reactions. The spectrometer consists of a magnetic quadrupole doublet which focuses the charged particles onto a silicon surface barrier detector telescope which is 2 meters or more from the irradiated sample. Collimators, shielding, and the large source-to-detector distance reduce the background enough to use the spectrometer with a 14-MeV neutron source producing 4 . 10 12 n/s. The spectrometer has been used in investigations of proton, deuteron, and alpha particle production by 14-MeV neutrons incident on various materials. Protons with energies as low as 1.1 MeV have been measured. The good resolution of the detectors has also made possible an improved measurement of the neutron- neutron scattering length from the 0 0 proton spectrum from deuteron breakup by 14-MeV neutrons

Spin, quadrupole moment, and deformation of the magnetic-rotational band head in Pb193

Science.gov (United States)

Balabanski, D. L.; Ionescu-Bujor, M.; Iordachescu, A.; Bazzacco, D.; Brandolini, F.; Bucurescu, D.; Chmel, S.; Danchev, M.; de Poli, M.; Georgiev, G.; Haas, H.; Hübel, H.; Marginean, N.; Menegazzo, R.; Neyens, G.; Pavan, P.; Rossi Alvarez, C.; Ur, C. A.; Vyvey, K.; Frauendorf, S.

2011-01-01

The spectroscopic quadrupole moment of the T1/2=9.4(5) ns isomer in Pb193 at an excitation energy Eex=(2585+x) keV is measured by the time-differential perturbed angular distribution method as |Qs|=2.6(3) e b. Spin and parity Iπ=27/2- are assigned to it based on angular distribution measurements. This state is the band head of a magnetic-rotational band, described by the 1i13/2 subshell with the (3s1/2-21h9/21i13/2)11- proton excitation. The pairing-plus-quadrupole tilted-axis cranking calculations reproduce the measured quadrupole moment with a moderate oblate deformation ɛ2=-0.11, similar to that of the 11-proton intruder states, which nuclei in the region. This is the first direct measurement of a quadrupole moment and thus of the deformation of a magnetic-rotational band head.

Collective Quadrupole Excitations of Transactinide Nuclei

CERN Document Server

Zajac, K; Pomorski, K; Rohozinski, S G; Srebrny, J

2003-01-01

The quadrupole excitations of transuranic nuclei are described in the frame of the microscopic Bohr Hamiltonian modified by adding the coupling with the collective pairing vibrations. The energies of the states from the ground-state bands in U to No even-even isotopes as well as the B(E2) transition probabilities are reproduced within the model containing no adjustable parameters.

Parametric Sensitivity Analysis of Oscillatory Delay Systems with an Application to Gene Regulation.

Science.gov (United States)

Ingalls, Brian; Mincheva, Maya; Roussel, Marc R

2017-07-01

A parametric sensitivity analysis for periodic solutions of delay-differential equations is developed. Because phase shifts cause the sensitivity coefficients of a periodic orbit to diverge, we focus on sensitivities of the extrema, from which amplitude sensitivities are computed, and of the period. Delay-differential equations are often used to model gene expression networks. In these models, the parametric sensitivities of a particular genotype define the local geometry of the evolutionary landscape. Thus, sensitivities can be used to investigate directions of gradual evolutionary change. An oscillatory protein synthesis model whose properties are modulated by RNA interference is used as an example. This model consists of a set of coupled delay-differential equations involving three delays. Sensitivity analyses are carried out at several operating points. Comments on the evolutionary implications of the results are offered.

Development and Test of LARP Technological Quadrupole (TQC) Magnet

Energy Technology Data Exchange (ETDEWEB)

Feher, S.; Bossert, R.C.; Ambrosio, G.; Andreev, N.; Barzi, E.; Carcagno, R.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Nobrega, F.; Novitski, I.; Pischalnikov, Yu.; Sylvester, C.; Tartaglia, M.; Turrioni, D.; Whitson, G.; Yamada, R.; Zlobin, A.V.; Caspi, S.; Dietderich, D.; Ferracin, P.; Hannaford, R.; Hafalia, A.R.; Sabbi, G.

2007-06-01

In support of the development of a large-aperture Nb{sub 3}Sn superconducting quadrupole for the Large Hadron Collider (LHC) luminosity upgrade, two-layer quadrupole models (TQC and TQS) with 90 mm aperture are being constructed at Fermilab and LBNL within the framework of the US LHC Accelerator Research Program (LARP). This paper describes the construction and test of model TQC01. ANSYS calculations of the structure are compared with measurements during construction. Fabrication experience is described and in-process measurements are reported. Test results at 4.5 K are presented, including magnet training, current ramp rate studies and magnet quench current. Results of magnetic measurements at helium temperature are also presented.

Development and Test of LARP Technological Quadrupole (TQC) Magnet

International Nuclear Information System (INIS)

Feher, S.; Bossert, R.C.; Ambrosio, G.; Andreev, N.; Barzi, E.; Carcagno, R.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Nobrega, F.; Novitski, I.; Pischalnikov, Yu.; Sylvester, C.; Tartaglia, M.; Turrioni, D.; Whitson, G.; Yamada, R.; Zlobin, A.V.; Caspi, S.; Dietderich, D.; Ferracin, P.; Hannaford, R.; Hafalia, A.R.; Sabbi, G.

2007-01-01

In support of the development of a large-aperture Nb 3 Sn superconducting quadrupole for the Large Hadron Collider (LHC) luminosity upgrade, two-layer quadrupole models (TQC and TQS) with 90 mm aperture are being constructed at Fermilab and LBNL within the framework of the US LHC Accelerator Research Program (LARP). This paper describes the construction and test of model TQC01. ANSYS calculations of the structure are compared with measurements during construction. Fabrication experience is described and in-process measurements are reported. Test results at 4.5 K are presented, including magnet training, current ramp rate studies and magnet quench current. Results of magnetic measurements at helium temperature are also presented

Development and test of LARP technological quadrupole (TQC) magnet

Energy Technology Data Exchange (ETDEWEB)

Feher, S.; Bossert, R.C.; Ambrosio, G.; Andreev, N.; Barzi, E.; Carcagno, R.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Nobrega, F.; Novitski, I.; /Fermilab /LBL, Berkeley

2006-08-01

In support of the development of a large-aperture Nb{sub 3}Sn superconducting quadrupole for the Large Hadron Collider (LHC) luminosity upgrade, two-layer quadrupole models (TQC and TQS) with 90-mm aperture are being constructed at Fermilab and LBNL within the framework of the US LHC Accelerator Research Program (LARP). This paper describes the construction and test of model TQC01. ANSYS calculations of the structure are compared with measurements during construction. Fabrication experience is described and in-process measurements are reported. Test results at 4.5K are presented, including magnet training, current ramp rate studies and magnet quench current . Results of magnetic measurements at helium temperature are also presented.

Development and test of LARP technological quadrupole (TQC) magnet

International Nuclear Information System (INIS)

Feher, S.; Bossert, R.C.; Ambrosio, G.; Andreev, N.; Barzi, E.; Carcagno, R.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Nobrega, F.; Novitski, I.

2006-01-01

In support of the development of a large-aperture Nb 3 Sn superconducting quadrupole for the Large Hadron Collider (LHC) luminosity upgrade, two-layer quadrupole models (TQC and TQS) with 90-mm aperture are being constructed at Fermilab and LBNL within the framework of the US LHC Accelerator Research Program (LARP). This paper describes the construction and test of model TQC01. ANSYS calculations of the structure are compared with measurements during construction. Fabrication experience is described and in-process measurements are reported. Test results at 4.5K are presented, including magnet training, current ramp rate studies and magnet quench current . Results of magnetic measurements at helium temperature are also presented

Nuclear quadrupole resonance of arsenolite

International Nuclear Information System (INIS)

Madarazo, R.

1988-01-01

A pulsed Nuclear Quadrupole Resonance (NQR) spectrometer was constructed using imported Matec units. Peripherical components were specially assembled and tested for the implantation of the spin-echo technique in the Laboratorio de Centros de Cor of IFUSP. The R.F. operation range is from 50 to 1 ) and spin-spin (T 2 ) relaxation times were carried out at room temperature in arsenolite. The 75 As NQR frequency measured at room temperature is 116.223 MHz. (author) [pt

Study and optimal correction of a systematic skew quadrupole field in the Tevatron

International Nuclear Information System (INIS)

Snopok, Pavel; Johnstone, Carol; Berz, Martin; Ovsyannikov, Dmitry A.; Ovsyannikov, Alexander D.

2006-01-01

Increasing demands for luminosity in existing and future colliders have made lattice design and error tolerance and correction critical to achieving performance goals. The current state of the Tevatron collider is an example, with a strong skew quadrupole error present in the operational lattice. This work studies the high-order performance of the Tevatron and the strong nonlinear behavior introduced when a significant skew quadrupole error is combined with conventional sextupole correction, a behavior still clearly evident after optimal tuning of available skew quadrupole circuits. An optimization study is performed using different skew quadrupole families, and, importantly, local and global correction of the linear skew terms in maps generated by the code COSY INFINITY [M. Berz, COSY INFINITY version 8.1 user's guide and reference manual, Department of Physics and Astronomy MSUHEP-20704, Michigan State University (2002). URL http://cosy.pa.msu.edu/cosymanu/index.html]. Two correction schemes with one family locally correcting each arc and eight independent correctors in the straight sections for global correction are proposed and shown to dramatically improve linearity and performance of the baseline Tevatron lattice

Determination of the effective quadrupole moment in $^{181}$Ta with pionic x-rays

CERN Document Server

Beetz, R; Fransson, K; Konijn, J; Panman, J; Tauscher, Ludwig; Tibell, G

1978-01-01

From the hyperfine splitting of the 5g to 4f and the 6g to 4f pionic X-rays in /sup 181/Ta, an effective quadrupole moment of Q/sub eff /=3.58+or-0.03 b was determined. The strong interaction monopole shift epsilon /sub 0/ and the width Gamma /sub 0/ of the 4f level were measured to be epsilon /sub 0/=540+or-100 eV and Gamma /sub 0 /=225+or-57 eV, in good agreement with the values obtained with the standard optical potential description of the pion-nucleus interaction. Estimating the influence of the finite nuclear size, the deformation induced through the strong interaction between the pion and the finite nucleus, and the relative magnitude between the strong and the electromagnetic quadrupole coupling constants values for the spectroscopic quadrupole moment of Q=3.30+or-0.06 b, and for the intrinsic quadrupole moment of Q/sub 0/=7.06+or-0.12 b are obtained. (28 refs).

Relativistic Quadrupole Polarizability for the Ground State of Hydrogen-Like Ions

International Nuclear Information System (INIS)

Zhang Yong-Hu; Zhang Xian-Zhou; Tang Li-Yan; Shi Ting-Yun; Mitroy Jim

2012-01-01

The static quadrupole polarizabilities for hydrogen-like ions from Z = 1 to Z = 100 in the 1S 1/2 ground state are calculated to high precision by solving the Dirac equation using the B-spline Galerkin method. The results are consistent with the expression of Kaneko [J. Phys. B 10 (1977) 3347] at low Z. The quadrupole oscillator strength sum Σ n f (2) gn is computed to be zero to a very high degree of precision. (atomic and molecular physics)

On stellar collapse: continual or oscillatory. A short comment

International Nuclear Information System (INIS)

Leung, P.T.

1980-01-01

We comment on a previously published paper on the oscillatory dynamics of stellar collapse and conclude that the Schwarzschild interior solution applied to the 'inflection points' can never give rise to a 'turning back' motion, in spite of the fact that the geodesic equation really does not always describe an attractive gravitational acceleration

New insights into strobe reactions: An intriguing oscillatory combustion phenomenon

NARCIS (Netherlands)

Corbel, J.M.L.

2013-01-01

Strobes are self-sustained oscillatory combustions that have various applications in the fireworks industry and also in the military area (signaling, missile decoys and crowd control). However, most of the strobe compositions were discovered using trial and error methods. The fundamentals mechanisms

Effect of quadrupole fringe fields on the tune of Indus-2

International Nuclear Information System (INIS)

Kant, Pradeep; Husain, Riyasat; Ghodke, A.D.; Singh, Gurnam

2009-01-01

Being an unavoidable part in a real magnet design, fringe fields of different kind of magnets have various effects on the beam parameters of the storage ring. The fringe field of a bending magnet (dipole) generates closed orbit distortion and disturbs the dispersion function whereas the fringe field of a quadrupole affects other parameters of the ring like tune values and twiss functions. The fringe field pattern of the quadrupoles of Indus-2 was measured by the Magnet Group. The measurements were performed along the various radial tracks in a quadrupole from -30 to 30 mm in steps of 5 mm at various excitation current levels. The pattern of the gradient at these different current levels was obtained by a line fit of the magnetic field at each point. The data was used to get the effect on the tune of Indus-2. The paper describes the results of the effect on the tune. (author)

Deterioration of the Skew Quadrupole Moment in Tevatron Dipoles Over Time

CERN Document Server

Syphers, Michael J

2005-01-01

During the 20 years since it was first commissioned, the Fermilab Tevatron has developed strong coupling between the two transverse degrees of freedom. A circuit of skew quadrupole magnets is used to correct for coupling and, though capable, its required strength has increased since 1983 by more than an order of magnitude. In more recent years changes to the Tevatron for colliding beams operation have altered the skew quadrupole corrector distribution and strong local coupling become evident, often encumbering routine operation during the present physics run. Detailed magnet measurements were performed on each individual magnet during construction, and in early 2003 it was realized that measurements could be performed on the magnets in situ which could determine coil movements within the iron yoke since the early 1980's. It was discovered that the superconducting coils had become vertically displaced relative to their yokes since their construction. The ensuing systematic skew quadrupole field introduced by t...

Enhancing Rotational Diffusion Using Oscillatory Shear

KAUST Repository

Leahy, Brian D.

2013-05-29

Taylor dispersion - shear-induced enhancement of translational diffusion - is an important phenomenon with applications ranging from pharmacology to geology. Through experiments and simulations, we show that rotational diffusion is also enhanced for anisotropic particles in oscillatory shear. This enhancement arises from variations in the particle\\'s rotation (Jeffery orbit) and depends on the strain amplitude, rate, and particle aspect ratio in a manner that is distinct from the translational diffusion. This separate tunability of translational and rotational diffusion opens the door to new techniques for controlling positions and orientations of suspended anisotropic colloids. © 2013 American Physical Society.

Abnormal Task Modulation of Oscillatory Neural Activity in Schizophrenia

Directory of Open Access Journals (Sweden)

Elisa C Dias

2013-08-01

Full Text Available Schizophrenia patients have deficits in cognitive function that are a core feature of the disorder. AX-CPT is commonly used to study cognition in schizophrenia, and patients have characteristic pattern of behavioral and ERP response. In AX-CPT subjects respond when a flashed cue A is followed by a target X, ignoring other letter combinations. Patients show reduced hit rate to go trials, and increased false alarms to sequences that require inhibition of a prepotent response. EEG recordings show reduced sensory (P1/N1, as well as later cognitive components (N2, P3, CNV. Behavioral deficits correlate most strongly with sensory dysfunction. Oscillatory analyses provide critical information regarding sensory/cognitive processing over and above standard ERP analyses. Recent analyses of induced oscillatory activity in single trials during AX-CPT in healthy volunteers showed characteristic response patterns in theta, alpha and beta frequencies tied to specific sensory and cognitive processes. Alpha and beta modulated during the trials and beta modulation over the frontal cortex correlated with reaction time. In this study, EEG data was obtained from 18 schizophrenia patients and 13 controls during AX-CPT performance, and single trial decomposition of the signal yielded power in the target wavelengths.Significant task-related event-related desynchronization (ERD was observed in both alpha and beta frequency bands over parieto-occipital cortex related to sensory encoding of the cue. This modulation was reduced in patients for beta, but not for alpha. In addition, significant beta ERD was observed over motor cortex, related to motor preparation for the response, and was also reduced in patients. These findings demonstrate impaired dynamic modulation of beta frequency rhythms in schizophrenia, and suggest that failures of oscillatory activity may underlie impaired sensory information processing in schizophrenia that in turn contributes to cognitive deficits.

The Oscillatory Nature of Rotating Convection in Liquid Metal

Science.gov (United States)

Aurnou, J. M.; Bertin, V. L.; Grannan, A. M.

2016-12-01

Earth's magnetic field is assumed to be generated by fluid motions in its liquid metal core. In this fluid, the heat diffuses significantly more than momentum and thus, the ratio of these two diffusivities, the Prandtl number Pr=ν/Κ, is well below unity. The convective flow dynamics of liquid metal is very different from Pr ≈ 1 fluids like water and those used in current dynamo simulations. In order to characterize rapidly rotating thermal convection in low Pr number fluids, we have performed laboratory experiments in a cylinder using liquid gallium (Pr ≈ 0.023) as the working fluid. The Ekman number, which characterizes the effect of rotation, varies from E = 4 10-5 to 4 10-6 and the dimensionless buoyancy forcing (Rayleigh number, Ra) varies from Ra =3 105 to 2 107. Using heat transfer measurements (Nusselt number, Nu) as well as temperature measurements within the fluid, we characterize the different styles of low Pr rotating convective flow. The convection threshold is first overcome in the form of a container scale inertial oscillatory mode. At stronger forcing, wall-localized modes are identified for the first time in liquid metal laboratory experiments. These wall modes coexist with the bulk inertial oscillatory modes. When the strengh of the buoyancy increases, the bulk flow becomes turbulent while the wall modes remain. Our results imply that rotating convective flows in liquid metals do not develop in the form of quasi-steady columns, as in Pr ≈ 1 dynamo models, but in the form of oscillatory motions. Therefore, the flows that drive thermally-driven dynamo action in low Pr geophysical and astrophysical fluids can differ substantively than those occuring in current-day Pr ≈ 1 numerical models. In addition, our results suggest that relatively low wavenumber, wall-attached modes may be dynamically important in rapidly-rotating convection in liquid metals.

Self-focusing of whistler waves

Science.gov (United States)

Karpman, V. I.; Kaufman, R. N.; Shagalov, A. G.

1992-01-01

The theory of axially symmetric self-focusing of whistler waves, based on the full system of Maxwell equations, is developed. The plasma is described by the magnetohydrodynamic equations including the ponderomotive force from RF field. The nonlinear Schrodinger equations (NSE) for arbitrary azimuthal modes of whistler waves are derived. It is shown that they differ from the NSE for a scalar field; this is connected with an intrinsic angular momentum due to the rotating polarization of whistlers. It is shown that the self-focusing, as described by the NSE, differs in its final stage from the results following the full set of Maxwell equations. The latter gives defocusing after sufficient narrowing of the initial wave beam, due to transformation of the trapped wave into a nontrapped branch which is not contained in the NSE description. The oscillatory character of the defocusing is demonstrated.

The effect and correction of coupling generated by the RHIC triplet quadrupoles

International Nuclear Information System (INIS)

Pilat, F.; Peggs, S.; Tepikian, S.; Trbojevic, D.; Wei, J.

1995-01-01

This study explores the possibility of operating the nominal RHIC coupling correction system in local decoupling mode, where a subset of skew quadrupoles are independently set by minimizing the coupling as locally measured by beam position monitors. The goal is to establish a correction procedure for the skew quadrupole errors in the interaction region triplets that does not rely on a priori knowledge of the individual errors. After a description of the present coupling correction scheme envisioned for RHIC, the basics of the local decoupling method will be briefly recalled in the context of its implementation in the TEAPOT simulation code as well as operationally. The method is then applied to the RHIC lattice: a series of simple tests establish that single triplet skew quadrupole errors can be corrected by local decoupling. More realistic correction schemes are then studied in order to correct distributed sources of skew quadrupole errors: the machine can be decoupled either by pure local decoupling or by a combination of global (minimum tune separation) and local decoupling. The different correction schemes are successively validated and evaluated by standard RHIC simulation runs with the complete set of errors and corrections. The different solutions and results are finally discussed together with their implications for the hardware

Drift Compression and Final Focus for Intense Heavy Ion Beams with Non-periodic, Time-dependent Lattice

International Nuclear Information System (INIS)

Hong Qin; Davidson, Ronald C.; Barnard, John J.; Lee, Edward P.

2005-01-01

In the currently envisioned configurations for heavy ion fusion, it is necessary to longitudinally compress the beam bunches by a large factor after the acceleration phase. Because the space-charge force increases as the beam is compressed, the beam size in the transverse direction will increase in a periodic quadrupole lattice. If an active control of the beam size is desired, a larger focusing force is needed to confine the beam in the transverse direction, and a non-periodic quadrupole lattice along the beam path is necessary. In this paper, we describe the design of such a focusing lattice using the transverse envelope equations. A drift compression and final focus lattice should focus the entire beam pulse onto the same focal spot on the target. This is difficult with a fixed lattice, because different slices of the beam may have different perveance and emittance. Four time-dependent magnets are introduced in the upstream of drift compression to focus the entire pulse onto the sam e focal spot. Drift compression and final focusing schemes are developed for a typical heavy ion fusion driver and for the Integrated Beam Experiment (IBX) being designed by the Heavy Ion Fusion Virtual National Laboratory

Radiation-induced effects on the sensors of the Hydrostatic Leveling System for the LHC low-beta quadrupoles

CERN Document Server

Dimovasili, E; Mainaud-Durand, H; Marin, A; Ossart, F; Wijnands, Thijs

2005-01-01

The dose rate dependence of the Hydrostatic Leveling System (HLS) for the final focusing quadrupole magnets in the Large Hadron collider is discussed. At high dose rates, ionization of the air inside the sensors causes charge deposition and this perturbs the position measurement. A model is presented that corrects the HLS signal offset as a function of the dose rate. The model compares the HLS with condenser ionization chambers and in this note the results of the comparison are presented.

Oscillatory Mechanisms of Stimulus Processing and Selection in the Visual and Auditory Systems: State-of-the-Art, Speculations and Suggestions

Directory of Open Access Journals (Sweden)

Benedikt Zoefel

2017-05-01

Full Text Available All sensory systems need to continuously prioritize and select incoming stimuli in order to avoid overflow or interference, and provide a structure to the brain's input. However, the characteristics of this input differ across sensory systems; therefore, and as a direct consequence, each sensory system might have developed specialized strategies to cope with the continuous stream of incoming information. Neural oscillations are intimately connected with this selection process, as they can be used by the brain to rhythmically amplify or attenuate input and therefore represent an optimal tool for stimulus selection. In this paper, we focus on oscillatory processes for stimulus selection in the visual and auditory systems. We point out both commonalities and differences between the two systems and develop several hypotheses, inspired by recently published findings: (1 The rhythmic component in its input is crucial for the auditory, but not for the visual system. The alignment between oscillatory phase and rhythmic input (phase entrainment is therefore an integral part of stimulus selection in the auditory system whereas the visual system merely adjusts its phase to upcoming events, without the need for any rhythmic component. (2 When input is unpredictable, the visual system can maintain its oscillatory sampling, whereas the auditory system switches to a different, potentially internally oriented, “mode” of processing that might be characterized by alpha oscillations. (3 Visual alpha can be divided into a faster occipital alpha (10 Hz and a slower frontal alpha (7 Hz that critically depends on attention.

Solid state NMR, basic theory and recent progress for quadrupole nuclei with half-integer spin

International Nuclear Information System (INIS)

Dieter, F.

1998-01-01

This review describes the basic theory and some recently developed techniques for the study of quadrupole nuclei with half integer spins in powder materials. The latter is connected to the introduction of the double rotation (DOR) by A. Samoson et al. (1) and to the introduction of the multiple quantum magic-angle spinning (MQ MAS) technique by L. Frydman et. al. (2). For integer spins, especially the solid-state deuterium magnetic resonance, we refer to the review of G.L. Hoatson and R.L. Vold: '' 2 H-NMR Spectroscopy of Solids and Liquid Crystals'' (3). For single crystals we refer to O. Kanert and M. Mehring: ''Static quadrupole effects in disordered cubic solids''(4) and we would like also to mention the ''classic'' review of M.H. Cohen and F. Reif: ''Quadrupole effects in NMR studies of solids'' (5). Some more recent reviews in the field under study are D. Freude and J. Haase ''Quadrupole effects in solid-state NMR'' (6). Ch. Jager: ''Satellite Transition Spectroscopy of Quadrupolar Nuclei'' (7) and B.F. Chmelka and J.W. Zwanziger: ''Solid State NMR Line Narrowing Methods for Quadrupolar Nuclei - Double Rotation and Dynamic-Angle Spinning'' (8). A survey of nuclear quadrupole frequency data published before the end of 1982 is given by H. Chihara and N. Nakamura in Landolt-Bornstein, Vol. 20 (9). Values of the chemical shift of quadrupole nuclei in solids can be found in books such as ''Multinuclear NMR'' edited by J. Mason (10). In section 9 of ref (6) some electric field gradient and chemical shift data published from 1983 to 1992 for the most studied quadrupole nuclei sup 27 Al, sup 23 Na, and sup 17 O are given

Oscillatory device for use with linear tribometer, for tribological evaluation of biomaterials

Science.gov (United States)

Athayde, J. N.; Siqueira, C. J. M.; Kuromoto, N. K.; Cambraia, H. N.

2017-07-01

Orthopedic implants still have limitations regarding their durability, despite being in use for over fifty years. Particles arising from wear due to the relative motion of their surfaces remain responsible for aseptic failure. This paper presents a device to be coupled with a reciprocal linear tribometer to reproduce the ex vivo wear of biomaterials, allowing the measurement of force and coefficient of friction. The device consists of a structure connected to the tribometer that transforms its reciprocal linear motion into one that is oscillatory for the mechanical assembly that contains the samples to test the desired biomaterials. The tribological pair used for testing consisted of Ultra High Molecular Weight Polyethylene (UHMWPE) in conjunction with the austenitic stainless steel AISI 316L in dry lubrication. The results showed that the values of the coefficient of friction in the linear mode and oscillatory mode and the UHMWPE life curve in the oscillatory mode were consistent with those cited in the literature for tests in a dry lubrication environment. Moreover, the UHMWPE sample life curve showed a reduction in the wear rate that can be explained by the preponderance of a wear mechanism over the others. The volumetric wear showed an increase with the number of cycles.

Rotations as coherent states of SU(6) quadrupole phonons in the SU(3) limit

Energy Technology Data Exchange (ETDEWEB)

Canto, L F [Rio de Janeiro Univ. (Brazil). Inst. de Fisica; Paar, V [Zagreb Univ. (Yugoslavia). Prirodoslovno Matematicki Fakultet; Rio de Janeiro Univ. (Brazil). Inst. de Fisica)

1981-06-18

Analytic expressions for the wavefunctions of the ground-state rotational band for even and odd nuclei are derived in terms of spherical quadrupole phonons truncated at N(max) phonons. For N(max) ..-->.. infinite the Bohr-Mottelson rotational states are generated as an asymptotic gaussian distribution of quadrupole phonons.

High-Energy Gun-Injected Toroidal Quadrupole

International Nuclear Information System (INIS)

Hammel, J.E.; Henins, I.; Kewish, R.W. Jr.; Marshall, J.; Sherwood, A.R.

1971-01-01

A quadrupole device is being used to investigate the trapping and containment of an energetic gun plasma. The quadrupole is designed to contain a peak density of 5 x 10 13 cm -3 at 2.5 keV within the MHD-stable region. At design field there are 5 gyro-radii for 2. 5-keV protons from the separatrix to the ψ crit . The interior conductors are directly driven with a 0.8-MJ capacitor bank. The current to the coils is fed through a single pair of dipole-guarded conductors to each coil. The coils are also supported from the current feed, The dipole guard is in a force-free configuration with 5 gyro-radii for 2. 5-keV protons from the separatrix (between the dipole and quadrupole fields) to the dipole surface. The dipole is designed so that loss of plasma from the dipole region will be directed away from the interior conductors. This feature is necessary for the prevention of contamination by secondary gas produced by plasma lost at the dipole guard. Experiments at one-half design value of magnetic field have shown that the kilovolt energy gun plasma is trapped by depolarization currents around the coils, and that a very high percentage (>50%) of the gun output can be trapped. The plasma density is measured by a unique Michelson interferometer using CO 2 laser light. The energy of the plasma is derived from magnetic pickup loops placed outside the containment region. The leak caused by the dipole guard Held has been examined by double electric probe measurements. The plasma drift thus inferred is an order of magnitude less than that predicted by a model of Meade's or by calculations by us. This casts doubt upon the validity of any such simple model and emphasizes the necessity of further experimental investigation of the matter. New coils which are being built to operate at full design magnetic field strength will allow a check on the containment time of the device for kilovolt energy plasma. (author)

The effect of quadrupole fields on particle confinement in a field-reversed mirror

International Nuclear Information System (INIS)

McColl, D.B.; Berk, H.L.; Hammer, J.; Morse, E.C.

1982-01-01

A particle simulation code has been modified to simulate particle loss caused by quadrupole magnetic fields on a field-reversed mirror plasma device. Since analytic fields are chosen for the equilibrium, the numerical algorithm is highly accurate for long-time integrations of particle orbits. The resultant particle loss due to the quadrupole fields can be competitive with collisional loss in the device

Quadrupole moment and a proton halo structure in 17F (Iπ = 5/2+)

International Nuclear Information System (INIS)

Zhou Dongmei; Zheng Yongnan; Yuan Daqing; Xizhen, Zhang; Zuo Yi; Minamisono, T; Matsuta, M; Fukuda, M; Mihara, M; Zhang Chunlei; Zhiqiang, Wang; Du Enpeng; Luo Hailong; Xu Guoji; Zhu Shengyun

2007-01-01

The quadrupole moment of light nuclei 17 F in the ground state (I π = 5/2 + ) is measured by the β-NMR method. The effective charge of the last proton in a d 5/2 orbit for 17 F is extracted from the measured quadrupole moment Q( 17 F) divided by the quadrupole moment Q sp calculated with a single particle model. A proton effective charge of e eff p = 1.12 ± 0.07e is obtained, which is in agreement with that given by a particle-vibration coupling model calculation within the experimental error. The present value of the proton effective charge is strong evidence for the existence of a proton skin in 17 F (I π = 5/2 + )

Nonlinear oscillatory rheology and structure of wormlike micellar solutions and colloidal suspensions

Science.gov (United States)

Gurnon, Amanda Kate

The complex, nonlinear flow behavior of soft materials transcends industrial applications, smart material design and non-equilibrium thermodynamics. A long-standing, fundamental challenge in soft-matter science is establishing a quantitative connection between the deformation field, local microstructure and macroscopic dynamic flow properties i.e., the rheology. Soft materials are widely used in consumer products and industrial processes including energy recovery, surfactants for personal healthcare (e.g. soap and shampoo), coatings, plastics, drug delivery, medical devices and therapeutics. Oftentimes, these materials are processed by, used during, or exposed to non-equilibrium conditions for which the transient response of the complex fluid is critical. As such, designing new dynamic experiments is imperative to testing these materials and further developing micromechanical models to predict their transient response. Two of the most common classes of these soft materials stand as the focus of the present research; they are: solutions of polymer-like micelles (PLM or also known as wormlike micelles, WLM) and concentrated colloidal suspensions. In addition to their varied applications these two different classes of soft materials are also governed by different physics. In contrast, to the shear thinning behavior of the WLMs at high shear rates, the near hard-sphere colloidal suspensions are known to display increases, sometimes quite substantial, in viscosity (known as shear thickening). The stress response of these complex fluids derive from the shear-induced microstructure, thus measurements of the microstructure under flow are critical for understanding the mechanisms underlying the complex, nonlinear rheology of these complex fluids. A popular micromechanical model is reframed from its original derivation for predicting steady shear rheology of polymers and WLMs to be applicable to weakly nonlinear oscillatory shear flow. The validity, utility and limits of

Quadrupole collective correlations and termination of the superdeformed bands in mercury

International Nuclear Information System (INIS)

Bonche, P.; Heenen, P.H.; Krieger, S.J.; Weiss, M.S.; Meyer, J.

1990-03-01

Fully self-consistent Generator Coordinate Method calculations have been performed on a basis of quadrupole constrained Hartree-Fock plus BCS wave functions for the five even mercury isotopes 190-198 Hg. The GCM results support conclusions drawn from previous HF+BCS calculations. The predicted evolution of superdeformed band head (shape isomer) properties as a function of the neutron number is consistent with the data. Using calculated transition matrix elements, we evaluate in-band versus out-of-band quadrupole decay and explain the sudden termination of the superdeformed band

Fringe fields modeling for the high luminosity LHC large aperture quadrupoles

CERN Document Server

Dalena, B; Payet, J; Chancé, A; Brett, D R; Appleby, R B; De Maria, R; Giovannozzi, M

2014-01-01

The HL-LHC Upgrade project relies on large aperture magnets (mainly the inner Triplet and the separation dipole D1). The beam is much more sensitive to non-linear perturbations in this region, such as those induced by the fringe fields of the low-beta quadrupoles. Different tracking models are compared in order to provide a numerical estimate of the impact of fringe fields for the actual design of the inner triplet quadrupoles. The implementation of the fringe fields in SixTrack, to be used for dynamic apertures studies, is also discussed.

Effect of magnetic quadrupole lens alignment on a nuclear microprobe resolution

International Nuclear Information System (INIS)

Kolinko, S.V.; Ponomarev, A.G.

2016-01-01

The paper reports the research trends in developing probe-forming systems with high demagnification and analysis factors that limit a nuclear microprobe resolution. Parasitic aberrations caused by tilts and offsets of magnetic quadrupoles are studied in terms of their effect on probe parameters on a target. The most common arrangements of probe-forming systems such as a triplet and “Russian quadruplet” with separated geometry are considered. The accuracy prerequisites for the positioning of the quadrupoles are defined, and practical guidelines for alignment of probe-forming systems with high demagnification factors are suggested.

Polarization of very cold neutron using a permanent magnet quadrupole

Energy Technology Data Exchange (ETDEWEB)

Yoshioka, Tamaki, E-mail: tyosioka@post.kek.j [High Energy Accelerator Research Organization, Ibaraki 305-0801 (Japan); Mishima, Kenji; Ino, Takashi; Taketani, Kaoru; Muto, Suguru; Morishima, Takahiro; Shimizu, Hirohiko M. [High Energy Accelerator Research Organization, Ibaraki 305-0801 (Japan); Oku, Takayuki; Suzuki, Junichi; Shinohara, Takenao; Sakai, Kenji [Japan Atomic Energy Agency, Ibaraki 319-1195 (Japan); Sato, Hiromi; Hirota, Katsuya; Otake, Yoshie [RIKEN, Saitama 351-0198 (Japan); Kitaguchi, Masaaki; Hino, Masahiro [Research Reactor Institute, Kyoto University, Osaka 590-0494 (Japan); Seki, Yoshichika [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Iwashita, Yoshihisa; Yamada, Masako [Institute for Chemical Research, Kyoto University, Kyoto 611-0011 (Japan); Ichikawa, Masahiro [Department of Physics, The University of Tokyo, Tokyo 113-0033 (Japan)

2011-04-01

For the future fundamental physics experiments by using cold neutrons, we are developing a device which can measure the neutron polarization degree by accuracy significantly below 10{sup -3}. A quadrupole magnet is one of the promising candidate to measure the neutron polarization degree by such extremely high precision. We have performed a polarization experiment by using the quadrupole magnets at the Very Cold Neutron (VCN) port of the PF-2 in the Institute Laue-Langevin (ILL). As a result, we obtained the polarization degree P with very high accuracy P=0.9994{+-}0.0001(stat.){+-}0.0003(syst.), which meet our requirement significantly.

Kinetic insights over a PEMFC operating on stationary and oscillatory states.

Science.gov (United States)

Mota, Andressa; Gonzalez, Ernesto R; Eiswirth, Markus

2011-12-01

Kinetic investigations in the oscillatory state have been carried out in order to shed light on the interplay between the complex kinetics exhibited by a proton exchange membrane fuel cell fed with poisoned H(2) (108 ppm of CO) and the other in serie process. The apparent activation energy (E(a)) in the stationary state was investigated in order to clarify the E(a) observed in the oscillatory state. The apparent activation energy in the stationary state, under potentiostatic control, rendered (a) E(a) ≈ 50-60 kJ mol(-1) over 0.8 V < E < 0.6 V and (b) E(a) ≈ 10 kJ mol(-1) at E = 0.3 V. The former is related to the H(2) adsorption in the vacancies of the surface poisoned by CO and the latter is correlated to the process of proton conductivity in the membrane. The dependence of the period-one oscillations on the temperature yielded a genuine Arrhenius dependence with two E(a) values: (a) E(a) around 70 kJ mol(-1), at high temperatures, and (b) E(a) around 10-15 kJ mol(-1), at lower temperatures. The latter E(a) indicates the presence of protonic mass transport coupled to the essential oscillatory mechanism. These insights point in the right direction to predict spatial couplings between anode and cathode as having the highest strength as well as to speculate the most likely candidates to promote spatial inhomogeneities. © 2011 American Chemical Society

Bistable flapping of flexible flyers in oscillatory flow

Science.gov (United States)

Huang, Yangyang; Kanso, Eva

2016-11-01

Biological and bio-inspired flyers move by shape actuation. The direct control of shape variables for locomotory purposes is well studied. Less is known about indirect shape actuation via the fluid medium. Here, we consider a flexible Λ-flyer in oscillatory flow that is free to flap and rotate around its fixed apex. We study its motion in the context of the inviscid vortex sheet model. We first analyze symmetric flapping about the vertical axis of gravity. We find that there is a finite value of the flexibility that maximizes both the flapping amplitude and elastic energy storage. Our results show that rather than resonance, the flyer relies on fluidic effects to optimize these two quantities. We then perturb the flyer away from the vertical and analyze its stability. Four distinct types of rolling behavior are identified: mono-stable, bistable, bistable oscillatory rotations and chaotic dynamics. We categorize these types of behavior in terms of the flyer's and flow parameters. In particular, the transition from mono-stable to bistable behavior occurs at a constant value of the product of the flow amplitude and acceleration. This product can be interpreted as the ratio of fluidic drag to gravity, confirming the fluid role in this transition.

Assembly of the first model of MQXFS quadrupole magnet for Hi-Lumi

CERN Multimedia

AUTHOR|(CDS)2086825

2016-01-01

Building 927. Assembly of the first model of MQXFS quadrupole magnet for Hi-Lumi. The MQXF models are about 1.5 m long and are used to validate the design before start building the first long prototype. Two types of insertion quadrupoles will be built and installed in the LHC tunnel during LS3. LARP (US collaboration) will built MQXFA type (4.2 meters long) and MQXFB magnets (around 7 m long) will be built at CERN.

The development of compact magnetic quadrupoles for ILSE

International Nuclear Information System (INIS)

Faltens, A.; Mukherjee, S.; Brady, V.

1990-08-01

Magnetic focussing is selected for the 4 MeV to 10 MeV section of the Induction Linac Systems Experiments (ILSE) to study the transport of magnetically focussed spacecharge-dominated beams and to explore the engineering problems in accurate positioning of the magnetic fields in an array of quadrupoles. A prototype development program for such magnets is currently under way. A compact design was selected to decrease the overall accelerator diameter and its cost. The design evolved from a cosine 2θ current distribution, corrected for end effects. Current-dominated magnets are used in a pulsed mode to allow higher current densities compared to standard dc water-cooled conductors. The POISSON and MAFCO codes were used in the design of the magnets. The construction of the quadrupoles is aimed at achieving location accuracy of the magnetic center to within 1 mil (2.54 x 10 -5 m) of the mechanical center

Quadrupole moments of wobbling excitations in 163Lu

International Nuclear Information System (INIS)

Goergen, A.; Clark, R.M.; Cromaz, M.; Fallon, P.; Lee, I.Y.; Macchiavelli, A.O.; Ward, D.; Hagemann, G.B.; Sletten, G.; Huebel, H.; Bengtsson, R.

2004-01-01

Lifetimes of states in the triaxial strongly deformed bands of 163 Lu have been measured with the Gammasphere spectrometer using the Doppler-shift attenuation method. The bands have been interpreted as wobbling-phonon excitations from the characteristic electromagnetic properties of the transitions connecting the bands. Quadrupole moments are extracted for the zero-phonon yrast band and, for the first time, for the one-phonon wobbling band. The very similar results found for the two bands suggest a similar intrinsic structure and support the wobbling interpretation. While the in-band quadrupole moments for the bands show a decreasing trend towards higher spin, the ratio of the interband to the in-band transition strengths remains constant. Both features can be understood by a small increase in triaxiality towards higher spin. Such a change in triaxiality is also found in cranking calculations, to which the experimental results are compared

A high gradient quadrupole magnet for the SSC

International Nuclear Information System (INIS)

Taylor, C.; Caspi, S.; Helm, M.; Mirk, K.; Peters, C.; Wandesforde, A.

1987-01-01

A quadrupole magnet for the SSC has been designed with a gradient of 234 T/m at 6500 A. Coil I.D. is 40 mm. The two-layer windings have 9 inner turns and 13 outer turns per pole with a wedge-shaped space in each layer. The 30-strand cable is identical to that used in the outer layer of the SSC dipole magnet. Interlocking aluminum alloy collars are compressed around the coil using a four-way press and are locked with four keys. The collared coil is supported and centered in a cold split iron yoke. A one-meter model was constructed and tested. Design details including quench behavior are presented. The quadrupole magnets proposed for the main SSC rings have a design gradient of 230 T/m. For one proposed 60 degree lattice cell, each 3-m long quad is separated by five 17-m long dipole magnets

A large-aperture, low-resolution quadrupole separator for producing deposited cluster materials

CERN Document Server

Denby, P M

2000-01-01

A wide-aperture, low-resolution quadrupole separator for metal clusters is described. Its performance has been evaluated by numerical calculations of the trajectories of clusters. Operating in the frequency range from 5 to 100 KHz allows one to separate clusters in the mass range from 30000 to 300000 AMU and by suitable choice of the AC and DC voltages one can obtain a resolution of 0.15. At this resolution the transmission of clusters from a source is 100% over the selected mass range. By biasing the quadrupole it has been possible to obtain a very sharp cut-off between the transmitted clusters and those outside the selected range. Trajectory calculation for clusters deposited onto a biased 2 cm diameter substrate show that it is possible to keep the deposition energy below 25 eV for 90% of the clusters when the quadrupole is itself biased.

A large-aperture, low-resolution quadrupole separator for producing deposited cluster materials

Energy Technology Data Exchange (ETDEWEB)

Denby, P.M.; Eastham, D.A. E-mail: d.a.eastham@dl.ac.uk

2000-03-01

A wide-aperture, low-resolution quadrupole separator for metal clusters is described. Its performance has been evaluated by numerical calculations of the trajectories of clusters. Operating in the frequency range from 5 to 100 KHz allows one to separate clusters in the mass range from 30000 to 300000 AMU and by suitable choice of the AC and DC voltages one can obtain a resolution of 0.15. At this resolution the transmission of clusters from a source is 100% over the selected mass range. By biasing the quadrupole it has been possible to obtain a very sharp cut-off between the transmitted clusters and those outside the selected range. Trajectory calculation for clusters deposited onto a biased 2 cm diameter substrate show that it is possible to keep the deposition energy below 25 eV for 90% of the clusters when the quadrupole is itself biased.

A large-aperture, low-resolution quadrupole separator for producing deposited cluster materials

International Nuclear Information System (INIS)

Denby, P.M.; Eastham, D.A.

2000-01-01

A wide-aperture, low-resolution quadrupole separator for metal clusters is described. Its performance has been evaluated by numerical calculations of the trajectories of clusters. Operating in the frequency range from 5 to 100 KHz allows one to separate clusters in the mass range from 30000 to 300000 AMU and by suitable choice of the AC and DC voltages one can obtain a resolution of 0.15. At this resolution the transmission of clusters from a source is 100% over the selected mass range. By biasing the quadrupole it has been possible to obtain a very sharp cut-off between the transmitted clusters and those outside the selected range. Trajectory calculation for clusters deposited onto a biased 2 cm diameter substrate show that it is possible to keep the deposition energy below 25 eV for 90% of the clusters when the quadrupole is itself biased

Simulations of oscillatory systems with award-winning software, physics of oscillations

CERN Document Server

Butikov, Eugene I

2015-01-01

Deepen Your Students' Understanding of Oscillations through Interactive Experiments Simulations of Oscillatory Systems: with Award-Winning Software, Physics of Oscillations provides a hands-on way of visualizing and understanding the fundamental concepts of the physics of oscillations. Both the textbook and software are designed as exploration-oriented supplements for courses in general physics and the theory of oscillations. The book is conveniently structured according to mathematical complexity. Each chapter in Part I contains activities, questions, exercises, and problems of varying levels of difficulty, from straightforward to quite challenging. Part II presents more sophisticated, highly mathematical material that delves into the serious theoretical background for the computer-aided study of oscillations. The software package allows students to observe the motion of linear and nonlinear mechanical oscillatory systems and to obtain plots of the variables that describe the systems along with phase diagram...

On the contribution of motor planning to the retroactive cuing benefit in working memory: Evidence by mu and beta oscillatory activity in the EEG.

Science.gov (United States)

Schneider, Daniel; Barth, Anna; Wascher, Edmund

2017-11-15

Attention can be allocated toward mental representations in working memory also after the initial encoding of information has been completed. It was shown that focusing on only one item within working memory transfers this representation into a protected state, reducing its susceptibility to interference by incoming signals. The present study investigated the nature of this retroactive cue (retro-cue) benefit by means of oscillatory activity in the EEG. In a working memory task with a retro-cue indicating one, two or three memory representations as relevant and a block-wise distractor display presented after the retro-cue, participants had to remember the orientation of a colored bar. On behavioral level, we found that the interfering effect of the distractor display on memory performance could be prevented when a retro-cue reduced the number of attended representations in working memory. However, only the one-item retro-cue led to an overall increase in task performance compared to a condition without a retro-cue. The neural basis of this special representational status was investigated by means of oscillatory parameters in the EEG and a clustering approach on level of the independent components (ICs) in the signal. The retroactive reduction of attended working memory representations was reflected in a suppression of alpha power over right parietal and parieto-occipital sites. In addition, we found that an IC cluster representing oscillatory activity in the mu/beta range (10-12 Hz and 20-24 Hz) with a source in sensorimotor cortex revealed a power suppression already prior to the memory probe following the one-item retro-cue. This suggests that the retro-cue benefit results in large parts from the possibility to focus attention on one particular item in working memory and initiate motor planning processes already ahead of the probe stimulus indicating the respective response. Copyright © 2017 Elsevier Inc. All rights reserved.

Design and fabrication of the prototype superconducting quadrupole for the CERN LHC project

International Nuclear Information System (INIS)

Baze, J.M.; Cacaut, D.; Jacquemin, J.P.; Lyraud, C.; Michez, C.; Pabot, Y.; Perot, J.; Rifflet, J.M.; Toussaint, J.C.; Vedrine, P.

1992-01-01

Within the framework of the LHC R and D program, CERN and CEA/Saclay have established a collaboration to carry out, amongst others, the design, building and testing of a superconducting LHC prototype quadrupole at the Saclay laboratory. The cold mass of this quadrupole is presently under construction at Saclay. The quadrupole design features a twin aperture configuration, a gradient design features a twin aperture configuration, a gradient of 250T/m, a length of 3m and a free coil aperture of 56mm. European industries participate in this project by delivering components and fabrication the tooling according to specifications prepared by Saclay. This paper gives details of the magnet design and construction. Coil winding will start in summer 1991 and the first prototype should be assembled and ready for testing by mid 1992

Tolerance analyses of a quadrupole magnet for advanced photon source upgrade

Energy Technology Data Exchange (ETDEWEB)

Liu, J., E-mail: Jieliu@aps.anl.gov; Jaski, M., E-mail: jaski@aps.anl.gov; Borland, M., E-mail: borland@aps.anl.gov [Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL60439 (United States); Jain, A., E-mail: jain@bnl.gov [Superconducting Magnet Division, Brookhaven National Laboratory, P.O. Box 5000. Upton, NY 11973-5000 (United States)

2016-07-27

Given physics requirements, the mechanical fabrication and assembly tolerances for storage ring magnets can be calculated using analytical methods [1, 2]. However, this method is not easy for complicated magnet designs [1]. In this paper, a novel method is proposed to determine fabrication and assembly tolerances consistent with physics requirements, through a combination of magnetic and mechanical tolerance analyses. In this study, finite element analysis using OPERA is conducted to estimate the effect of fabrication and assembly errors on the magnetic field of a quadrupole magnet and to determine the allowable tolerances to achieve the specified magnetic performances. Based on the study, allowable fabrication and assembly tolerances for the quadrupole assembly are specified for the mechanical design of the quadrupole magnet. Next, to achieve the required assembly level tolerances, mechanical tolerance stackup analyses using a 3D tolerance analysis package are carried out to determine the part and subassembly level fabrication tolerances. This method can be used to determine the tolerances for design of other individual magnets and of magnet strings.

Tolerance analyses of a quadrupole magnet for advanced photon source upgrade

International Nuclear Information System (INIS)

Liu, J.; Jaski, M.; Borland, M.; Jain, A.

2016-01-01

Given physics requirements, the mechanical fabrication and assembly tolerances for storage ring magnets can be calculated using analytical methods [1, 2]. However, this method is not easy for complicated magnet designs [1]. In this paper, a novel method is proposed to determine fabrication and assembly tolerances consistent with physics requirements, through a combination of magnetic and mechanical tolerance analyses. In this study, finite element analysis using OPERA is conducted to estimate the effect of fabrication and assembly errors on the magnetic field of a quadrupole magnet and to determine the allowable tolerances to achieve the specified magnetic performances. Based on the study, allowable fabrication and assembly tolerances for the quadrupole assembly are specified for the mechanical design of the quadrupole magnet. Next, to achieve the required assembly level tolerances, mechanical tolerance stackup analyses using a 3D tolerance analysis package are carried out to determine the part and subassembly level fabrication tolerances. This method can be used to determine the tolerances for design of other individual magnets and of magnet strings.

Spin, quadrupole moment, and deformation of the magnetic-rotational band head in (193)Pb

CERN Document Server

Balabanski, D L; Iordachescu, A; Bazzacco, D; Brandolini, F; Bucurescu, D; Chmel, S; Danchev, M; De Poli, M; Georgiev, G; Haas, H; Hubel, H; Marginean, N; Menegazzo, R; Neyens, G; Pavan, P; Rossi Alvarez, C; Ur, C A; Vyvey, K; Frauendorf, S

2011-01-01

The spectroscopic quadrupole moment of the T(1/2) = 9.4(5) ns isomer in (193)Pb at an excitation energy E(ex) = (2585 + x) keV is measured by the time-differential perturbed angular distribution method as vertical bar Q(s)vertical bar = 2.6(3) e b. Spin and parity I(pi) = 27/2(-) are assigned to it based on angular distribution measurements. This state is the band head of a magnetic-rotational band, described by the coupling of a neutron hole in the 1i(13/2) subshell with the (3s(1/2)(-2)1h(9/2)1i(13/2))(11-) proton excitation. The pairing-plus-quadrupole tilted-axis cranking calculations reproduce the measured quadrupole moment with a moderate oblate deformation epsilon(2) = -0.11, similar to that of the 11(-)proton intruder states, which occur in the even-even Pb nuclei in the region. This is the first direct measurement of a quadrupole moment and thus of the deformation of a magnetic-rotational band head.

Performance of the LHC Arc Superconducting Quadrupoles Towards the End of their Series Fabrication

CERN Document Server

Tortschanoff, Theodor; Durante, M; Hagen, P; Klein, U; Krischel, D; Modena, M; Payn, A; Rossi, L; Sanfilippo, S; Schellong, B; Schirm, KM; Schmidt, P; Simon, F; Todesco, E; Wildner, E

2006-01-01

The fabrication of the 408 main arc quadrupole magnets and their cold masses will come to an end in summer 2006. A rich collection of measurement and test data has been accumulated and their analysis is presented in this paper. These data cover the fabrication and the efficiency in the use of the main components, the geometrical measurements and the achieved dimensional precision, the warm magnetic measurements in the factory and the performance at cold conditions, especially the training behaviour. The scrap rate of the Nb-Ti/Cu conductor as well as that of other components turned out to be acceptably low and the quench performance measured was in general very good. Most quadrupoles measured so far exceeded the operating field gradient with one or no quench. The multipole content at cold was measured for a limited number of quadrupoles in order to verify the warm-to-cold correlation. From the point of view of field quality, all quadrupoles could be accepted for the machine. The measures taken to overcome the...

Effect of Temperature on Oscillatory Behaviour of the System Containing Isomers of Hydroxybenzoic Acid in Batch Reactor

Directory of Open Access Journals (Sweden)

Masood A. Nath

2008-01-01

Full Text Available In the present paper a thorough study of temperature dependence on oscillatory behaviour of the Belousov-Zhabotinsky (BZ system containing the isomers of hydroxybenzoic acids + BrO3-+ Mn(II in aqueous acid medium (1.0 M H2SO4 at a fixed concentration of reacting species has been reported. On varying temperature, the oscillatory parameters like induction time, time period and number of oscillations show marked changes. These changes arise due to the position and number of hydroxyl groups in these isomers which affect the oscillations. Experimental observations have satisfactorily been explained by FKN mechanism and kinetic parameters. The oscillatory characteristics depend on the temperature dependence of the rate constant of the reaction controlling the inhibitory reaction steps (negative feedback

Spontaneous oscillatory rhythms in the degenerating mouse retina modulate retinal ganglion cell responses to electrical stimulation

Directory of Open Access Journals (Sweden)

Yong Sook eGoo

2016-01-01

Full Text Available Characterization of the electrical activity of the retina in the animal models of retinal degeneration has been carried out in part to understand the progression of retinal degenerative diseases like age-related macular degeneration (AMD and retinitis pigmentosa (RP, but also to determine optimum stimulus paradigms for use with retinal prosthetic devices. The models most studied in this regard have been the two lines of mice deficient in the β-subunit of phosphodiesterase (rd1 and rd10 mice, where the degenerating retinas exhibit characteristic spontaneous hyperactivity and oscillatory local field potentials (LFPs. Additionally, there is a robust ~10 Hz rhythmic burst of retinal ganglion cell (RGC spikes on the trough of the oscillatory LFP. In rd1 mice, the rhythmic burst of RGC spikes is always phase-locked with the oscillatory LFP and this phase-locking property is preserved regardless of postnatal ages. However, in rd10 mice, the frequency of the oscillatory rhythm changes according to postnatal age, suggesting that this rhythm might be a marker of the stage of degeneration. Furthermore when a biphasic current stimulus is applied to rd10 mice degenerate retina, distinct RGC response patterns that correlate with the stage of degeneration emerge. This review also considers the significance of these response properties.

Beam determination of quadrupole misalignments and beam position monitor biases in the SLC linac

International Nuclear Information System (INIS)

Lavine, T.L.; Seeman, J.T.; Atwood, W.B.; Himel, T.M.; Petersen, A.; Adolphsen, C.E.

1988-09-01

Misalignments of magnetic quadrupoles and biases in beam position monitors (BPMs) in the Stanford Linear Collider (SLC) linac can lead to a situation in which the beam is off-center in the disk-loaded waveguide accelerator structure. The off-center beam produces wakefields which can limit SLC performance by causing unacceptably large emittance growth. We present a general method for determining quadrupole misalignments and BPM biases in the SLC linac by using beam trajectory measurements. The method utilizes both electron and positron beams on opposite rf cycles in the same linac lattice to determine simultaneously magnetic quadrupole misalignments and BPM biases. The two-beam trajectory data may be acquired without interrupting SLC colliding beam operations. 2 refs., 5 figs

Simulation of a quadrupole resonator

Energy Technology Data Exchange (ETDEWEB)

Kleindienst, Raphael [Helmholtz Zentrum Berlin (Germany)

2013-07-01

Modern particle accelerators often rely on superconducting radio frequency (SRF) technology for accelerating cavities. In particular in CW operation, very high quality factors up into the high range are desirable, since one of the main cost drivers of such an accelerator, the cryogenic refrigeration plant, is inversely proportional to Q{sub 0}. Present day superconducting cavities are generally made of solid Niobium. A possibility to increase the quality factor as well as accelerating fields is to use thin film coated cavities. Apart from Niobium thin films, other superconducting materials, such as MgB{sub 2}, NbN and Nb{sub 3}Sn are promising candidates. Measuring and understanding the RF-properties of superconducting thin films, specifically the surface resistance, is needed to drive forward this development. Currently only few facilities exist capable of measuring the surface resistance of thin films samples with a resolution in the nano-ohm range at the operating frequency of typical cavities(e.g. L-band). A dedicated test stand consisting of a quadrupole resonator is therefore being constructed at the Helmholtz Zentrum Berlin. This system is based on the 400 MHz quadrupole resonator at CERN, with the design adapted to 433 MHz (making available the higher harmonic mode at 1.3 GHz) and optimized with respect to resolution and maximum achievable fields using simulation data obtained with CST Microwave Studio as well as ANSYS. The simulated design is being manufactured. An outlook for future physics runs is given.

LHC interaction region quadrupole cryostat design

International Nuclear Information System (INIS)

Nicol, T.H.; Darve, Ch.; Huang, Y.; Page, T.M.

2002-01-01

The cryostat of a Large Hadron Collider (LHC) Interaction Region (IR) quadrupole magnet consists of all components of the inner triplet except the magnet assembly itself. It serves to support the magnet accurately and reliably within the vacuum vessel, to house all required cryogenic piping, and to insulate the cold mass from heat radiated and conducted from the environment. It must function reliably during storage, shipping and handling, normal magnet operation, quenches, and seismic excitations, and must be able to be manufactured at low cost. The major components of the cryostat are the vacuum vessel, thermal shield, multi-layer insulation system, cryogenic piping, and suspension system. The overall design of a cryostat for superconducting accelerator magnets requires consideration of fluid flow, proper selection of materials for their thermal and structural performance at both ambient and operating temperature, and knowledge of the environment to which the magnets will be subjected over the course of their expected operating lifetime. This paper describes the current LHC IR inner triplet quadrupole magnet cryostats being designed and manufactured at Fermilab as part of the US-LHC collaboration, and includes discussions on the structural and thermal considerations involved in the development of each of the major systems

Description of surface quadrupole oscillations of heated spherical nuclei in the Brownian-motion approximation

International Nuclear Information System (INIS)

Svin'in, I.R.

1982-01-01

The Brownian motion of a quadrupole quantum oscillator is considered as a model of surface quadrupole oscillations of heated spherical nuclei. The integrals of the motion related to energy and angular momentum conservation are constructed and the wave functions are obtained for states with definite values of these integrals of the motion in the phonon representation

Neutron-proton ratios of collective quadrupole matrix elements in even Fe and Cr isotopes

International Nuclear Information System (INIS)

Antalik, R.

1989-01-01

M n /M p ratios are investigated within the QRPA framework for the low-lying quadrupole states and for isoscalar giant quadrupole resonances in 54,56,58 Fe and 50,52,54 Cr. Theoretical results for 2 l ? + states are in good agreement with empirical ones obtained from recent proton and pion inelastic scattering studies. 16 refs.; 3 tabs

Development of a totally computer-controlled triple quadrupole mass spectrometer system

International Nuclear Information System (INIS)

Wong, C.M.; Crawford, R.W.; Barton, V.C.; Brand, H.R.; Neufeld, K.W.; Bowman, J.E.

1983-01-01

A totally computer-controlled triple quadrupole mass spectrometer (TQMS) is described. It has a number of unique features not available on current commercial instruments, including: complete computer control of source and all ion axial potentials; use of dual computers for data acquisition and data processing; and capability for self-adaptive control of experiments. Furthermore, it has been possible to produce this instrument at a cost significantly below that of commercial instruments. This triple quadrupole mass spectrometer has been constructed using components commercially available from several different manufacturers. The source is a standard Hewlett-Packard 5985B GC/MS source. The two quadrupole analyzers and the quadrupole CAD region contain Balzers QMA 150 rods with Balzers QMG 511 rf controllers for the analyzers and a Balzers QHS-511 controller for the CAD region. The pulsed-positive-ion-negative-ion-chemical ionization (PPINICI) detector is made by Finnigan Corporation. The mechanical and electronics design were developed at LLNL for linking these diverse elements into a functional TQMS as described. The computer design for total control of the system is unique in that two separate LSI-11/23 minicomputers and assorted I/O peripherals and interfaces from several manufacturers are used. The evolution of this design concept from totally computer-controlled instrumentation into future self-adaptive or ''expert'' systems for instrumental analysis is described. Operational characteristics of the instrument and initial results from experiments involving the analysis of the high explosive HMX (1,3,5,7-Tetranitro-1,3,5,7-Tetrazacyclooctane) are presented

Working Around Cosmic Variance: Remote Quadrupole Measurements of the CMB

Science.gov (United States)

Adil, Arsalan; Bunn, Emory

2018-01-01

Anisotropies in the CMB maps continue to revolutionize our understanding of the Cosmos. However, the statistical interpretation of these anisotropies is tainted with a posteriori statistics. The problem is particularly emphasized for lower order multipoles, i.e. in the cosmic variance regime of the power spectrum. Naturally, the solution lies in acquiring a new data set – a rather difficult task given the sample size of the Universe.The CMB temperature, in theory, depends on: the direction of photon propagation, the time at which the photons are observed, and the observer’s location in space. In existing CMB data, only the first parameter varies. However, as first pointed out by Kamionkowski and Loeb, a solution lies in making the so-called “Remote Quadrupole Measurements” by analyzing the secondary polarization produced by incoming CMB photons via the Sunyaev-Zel’dovich (SZ) effect. These observations allow us to measure the projected CMB quadrupole at the location and look-back time of a galaxy cluster.At low redshifts, the remote quadrupole is strongly correlated to the CMB anisotropy from our last scattering surface. We provide here a formalism for computing the covariance and relation matrices for both the two-point correlation function on the last scattering surface of a galaxy cluster and the cross correlation of the remote quadrupole with the local CMB. We then calculate these matrices based on a fiducial model and a non-standard model that suppresses power at large angles for ~104 clusters up to z=2. We anticipate to make a priori predictions of the differences between our expectations for the standard and non-standard models. Such an analysis is timely in the wake of the CMB S4 era which will provide us with an extensive SZ cluster catalogue.

Improved focusing-and-deflection columns

International Nuclear Information System (INIS)

Mui, P.H.; Szilagyi, M.

1995-01-01

Our earlier design procedures for constructing quadrupole columns are further expanded to include octupole corrector units and ''octupole'' deflectors with no third-order harmonics. The additional complications are finer partitioning of the plates and increased number of voltage controllers. Two sample designs, one having only the additional octupole deflectors and one having both the deflectors and the correctors, are presented and compared to our previous quadrupole system. The additional octupole components are shown to be capable of increasing the current density from 30% to more than 300% for a four-plate system, designed to focus and scan the electron beam over a circular area of 0.25 mm radius. The electron beam is assumed to have an initial divergence of ±2.3 mrad, an initial energy of 6 kV, a total energy spread of 1 eV, and a final acceleration of 30 keV. These systems are then slightly reoptimized for a superficial comparison with the commercially available column by Micrion Corporation. The numerical results indicate a potential for substantial improvements, demonstrating the power of this design procedure. Finally, a discussion is presented on how the individual components can interact with each other to reduce the various aberrations. copyright 1995 American Vacuum Society

Development of formulation Q1As method for quadrupole noise prediction around a submerged cylinder

Directory of Open Access Journals (Sweden)

Yo-Seb Choi

2017-09-01

Full Text Available Recent research has shown that quadrupole noise has a significant influence on the overall characteristics of flow-induced noise and on the performance of underwater appendages such as sonar domes. However, advanced research generally uses the Ffowcs Williams–Hawkings analogy without considering the quadrupole source to reduce computational cost. In this study, flow-induced noise is predicted by using an LES turbulence model and a developed formulation, called the formulation Q1As method to properly take into account the quadrupole source. The noise around a circular cylinder in an underwater environment is examined for two cases with different velocities. The results from the method are compared to those obtained from the experiments and the permeable FW–H method. The results are in good agreement with the experimental data, with a difference of less than 1 dB, which indicates that the formulation Q1As method is suitable for use in predicting quadrupole noise around underwater appendages.

MQXFS1 Quadrupole Fabrication Report

CERN Document Server

Ambrosio, G; Bossert, R; Cavanna, E; Cheng, D; Chlachidize, G; Cooley, L D; Dietderich, D; Felice, H; Ferracin, P; Ghosh, A; Hafalia, R; Holik, E F; Izquierdo Bermudez, S; Juchno, M; Krave, S; Marchevsky, M; Muratore, J; Nobrega, F; Pan, H; Perez, J C; Pong, I; Prestemon, S; Ravaioli, E; Sabbi, G L; Santini, C; Schmalzle, J; Schmalzle, J; Stoynev, S; Strauss, T; Vallone, G; Wanderer, P; Wang, X; Yu, M

2017-01-01

This report presents the fabrication and QC data of MQXFS1, the first short model of the low-beta quadrupoles (MQXF) for the LHC High Luminosity Upgrade. It describes the conductor, the coils, and the structure that make the MQXFS1 magnet. Qualification tests and non-conformities are also presented and discussed. The fabrication of MQXFS1 was started before the finalization of conductor and coil design for MQXF magnets. Two strand design were used (RRP 108/127 and RRP 132/169). Cable and coil cross-sections were “first generation”.

MQXFS1 Quadrupole Fabrication Report

Energy Technology Data Exchange (ETDEWEB)

Ambrosio, G. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Anerella, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Bossert, R. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Cavanna, E. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Cheng, D. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Chlachidize, G. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Cooley, L. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Dietderich, D. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Felice, H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Ferracin, P. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Ghosh, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Hafalia, R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Holik, E. F. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Bermudez, S. Izquierdo [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Juchno, M. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Krave, S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Marchevsky, M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Muratore, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Nobrega, F. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Pan, H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Perez, J. C. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Pong, I. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Prestemon, S. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Ravaioli, E. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sabbi, G. L. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Santini, C. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Schmalzle, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stoynev, S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Strauss, T. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Vallone, G. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Wanderer, P. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wang, X. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Yu, M. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

2017-07-16

This report presents the fabrication and QC data of MQXFS1, the first short model of the low-beta quadrupoles (MQXF) for the LHC High Luminosity Upgrade. It describes the conductor, the coils, and the structure that make the MQXFS1 magnet. Qualification tests and non-conformities are also presented and discussed. The fabrication of MQXFS1 was started before the finalization of conductor and coil design for MQXF magnets. Two strand design were used (RRP 108/127 and RRP 132/169). Cable and coil cross-sections were “first generation”.

Dynamic behavior of the bray-liebhafsky oscillatory reaction controlled by sulfuric acid and temperature

Science.gov (United States)

Pejić, N.; Vujković, M.; Maksimović, J.; Ivanović, A.; Anić, S.; Čupić, Ž.; Kolar-Anić, Lj.

2011-12-01

The non-periodic, periodic and chaotic regimes in the Bray-Liebhafsky (BL) oscillatory reaction observed in a continuously fed well stirred tank reactor (CSTR) under isothermal conditions at various inflow concentrations of the sulfuric acid were experimentally studied. In each series (at any fixed temperature), termination of oscillatory behavior via saddle loop infinite period bifurcation (SNIPER) as well as some kind of the Andronov-Hopf bifurcation is presented. In addition, it was found that an increase of temperature, in different series of experiments resulted in the shift of bifurcation point towards higher values of sulfuric acid concentration.

Theory of enhanced second-harmonic generation by the quadrupole-dipole hybrid exciton

International Nuclear Information System (INIS)

Roslyak, Oleksiy; Birman, Joseph L

2008-01-01

We report calculated substantial enhancement of the second-harmonic generation (SHG) in cuprous oxide crystals, resonantly hybridized with an appropriate organic material (DCM2:CA:PS 'solid state solvent'). The quadrupole origin of the inorganic part of the quadrupole-dipole hybrid provides inversion symmetry breaking and the organic part contributes to the oscillator strength of the hybrid. We show that the enhancement of the SHG, compared to the bulk cuprous oxide crystal, is proportional to the ratio of the DCM2 dipole moment and the effective dipole moment of the quadrupole transitions in the cuprous oxide. It is also inversely proportional to the line-width of the hybrid and bulk excitons. The enhancement may be regulated by adjusting the organic blend (mutual concentration of the DCM2 and CA part of the solvent) and pumping conditions (varying the angle of incidence in the case of optical pumping or populating the minimum of the lower branch of the hybrid in the case of electrical pumping)

Magnetic and Engineering Analysis of an Adjustable Strength Permanent Magnet Quadrupole

CERN Document Server

Gottschalk, Stephen C

2005-01-01

Magnetic and engineering analyses used in the design of an adjustable strength permanent magnet quadrupole will be reported. The quadrupole designed has a pole length of 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient * length (GL) of 68.7Tesla. Analyses of magnetic strength, field quality, magnetic centerline, temperature compensation and dynamic eddy currents induced during field adjustments will be presented. Magnet sorting strategies, pole positioning sensitivity, component forces, and other sensitivity analyses will be presented. Engineering analyses of stress, deflection and thermal effects as well as compensation strategies will also be shown.

Engineering quadrupole magnetic flow sorting for the isolation of pancreatic islets

Energy Technology Data Exchange (ETDEWEB)

Kennedy, David J. [IKOtech, LLC, 3130 Highland Avenue, 3rd Floor, Cincinnati, OH 45219-2374 (United States)]. E-mail: David.Kennedy@IKOtech.com; Todd, Paul [SHOT, Inc., Greenville, IN (United States); Logan, Sam [SHOT, Inc., Greenville, IN (United States); Becker, Matthew [SHOT, Inc., Greenville, IN (United States); Papas, Klearchos K. [Diabetes Institute for Immunology and Transplantation, University of Minnesota, Minneapolis, MN (United States); Moore, Lee R. [Biomedical Engineering Department, Cleveland Clinic Foundation, Cleveland, OH (United States)

2007-04-15

Quadrupole magnetic flow sorting (QMS) is being adapted from the separation of suspensions of single cells (<15 {mu}m) to the isolation of pancreatic islets (150-350 {mu}m) for transplant. To achieve this goal, the critical QMS components have been modeled and engineered to optimize the separation process. A flow channel has been designed, manufactured, and tested. The quadrupole magnet assembly has been designed and verified by finite element analysis. Pumps have been selected and verified by test. Test data generated from the pumps and flow channel demonstrate that the fabricated channel and peristaltic pumps fulfill the requirements of successful QMS separation.

Engineering quadrupole magnetic flow sorting for the isolation of pancreatic islets

International Nuclear Information System (INIS)

Kennedy, David J.; Todd, Paul; Logan, Sam; Becker, Matthew; Papas, Klearchos K.; Moore, Lee R.

2007-01-01

Quadrupole magnetic flow sorting (QMS) is being adapted from the separation of suspensions of single cells (<15 μm) to the isolation of pancreatic islets (150-350 μm) for transplant. To achieve this goal, the critical QMS components have been modeled and engineered to optimize the separation process. A flow channel has been designed, manufactured, and tested. The quadrupole magnet assembly has been designed and verified by finite element analysis. Pumps have been selected and verified by test. Test data generated from the pumps and flow channel demonstrate that the fabricated channel and peristaltic pumps fulfill the requirements of successful QMS separation

Static quadrupole moment of the first excited state of 24Mg

International Nuclear Information System (INIS)

Fewell, M.P.; Hinds, S.; Kean, D.C.; Zabel, T.H.

1979-01-01

The static quadrupole moment Qsub(2+) and the B(E2;0 + → 2 + ) value for the first excited state of 24 Mg have been determined using the reorientation effect in Coulomb excitation. Surface barrier detectors at 90 0 and 172 0 were used to detect 24 Mg ions scattered from 208 Pb. It is found that Qsub(2+) = -18.1 +- 1.3 e.fm 2 , suggesting that, contrary to most previous experimental evidence, the quadrupole moment is in agreement with theoretical predictions. For B(E2;0 + → 2 + ) the value 443 +- 24 e 2 . fm 4 was obtained

An effect of nuclear electric quadrupole moments in thermonuclear fusion plasmas

Science.gov (United States)

De, B. R.; Srnka, L. J.

1978-01-01

Consideration of the nuclear electric quadrupole terms in the expression for the fusion Coulomb barrier suggests that this electrostatic barrier may be substantially modified from that calculated under the usual plasma assumption that the nuclei are electric monopoles. This effect is a result of the nonspherical potential shape and the spatial quantization of the nuclear spins of the fully stripped ions in the presence of a magnetic field. For monopole-quadrupole fuel cycles like p-B-11, the fusion cross-section may be substantially increased at low energies if the protons are injected at a small angle relative to the confining magnetic field.

ISR Superconducting Quadrupole Prototype:preparing the first test

CERN Multimedia

CERN PhotoLab

1976-01-01

The photo shows the first prototype quadrupole (still with an adjustable stainless steel shrinking cylinder) being lifted to be inserted in a vertical cryostat for testing. It attained the design field gradient without any quench.The persons are Pierre Rey and Michel Bouvier. See also 7702690X.

Propulsion of a microsubmarine using a thermally oscillatory approach

International Nuclear Information System (INIS)

Qiao, Lei; Luo, Cheng

2013-01-01

In this paper, motivated by the driving mechanism of a putt-putt toy boat, we explore the feasibility to propel a microsubmarine using a thermally oscillatory approach, which only requires a simple design and does not involve any complicated propulsive systems. We investigate the design, fabrication, actuation and horizontal motions of the corresponding microsubmarines. Based on the understanding gained through preliminary tests on two manually fabricated putt-putt boats, we designed and fabricated the prototype of a microsubmarine. Similar to a putt-putt boat, the prototype also uses a thermally oscillatory process for propulsion. In a cyclic period of this process, due to the expansion and shrinkage of a vapor bubble inside the reservoir of the submarine, liquid is first ejected outside and then sucked into the reservoir. Due to the difference in liquid flow directions between ejection and suction stages, a thrust is produced to propel the submarine. At an applied voltage of 16 V and pulse frequency of 100 Hz, the submarine was found to have the highest speed of 1.8 mm s −1 and longest travel distance of 12.6 mm. The corresponding thrust was estimated to be 67.6 nN. (paper)

Beam-based alignment and tuning procedures for e+e- collider final focus systems

International Nuclear Information System (INIS)

Bulos, F.; Burke, D.; Helm, R.; Irwin, J.; Odian, A.; Roy, G.; Ruth, R.; Yamamoto

1991-01-01

For future linear colliders, with very small emittances and beam sizes and demanding tolerances on final focus system alignment and magnet errors, it becomes increasingly important to use the beam as a diagnostic tool. The authors report here procedures they have identified and will be implemented in the Final Focus Test Beam at SLAC incorporating (1) quadrupole strength changes, (2) central orbit modifications, (3) spot size measurements, and (4) beam stability monitoring

Shadows of Music-Language Interaction on Low Frequency Brain Oscillatory Patterns

Science.gov (United States)

Carrus, Elisa; Koelsch, Stefan; Bhattacharya, Joydeep

2011-01-01

Electrophysiological studies investigating similarities between music and language perception have relied exclusively on the signal averaging technique, which does not adequately represent oscillatory aspects of electrical brain activity that are relevant for higher cognition. The current study investigated the patterns of brain oscillations…

Adjustable permanent quadrupoles for the next linear collider

International Nuclear Information System (INIS)

Volk, James T.

2001-01-01

The proposed Next Linear Collider (NLC) will require over 1400 adjustable quadrupoles between the main linacs' accelerator structures. These 12.7 mm bore quadrupoles will have a range of integrated strength from 0.6 to 138 Tesla, with a maximum gradient of 141 Tesla per meter, an adjustment range of +0 to -20% and effective lengths from 324 mm to 972 mm. The magnetic center must remain stable to within 1 micron during the 20% adjustment. In an effort to reduce costs and increase reliability, several designs using hybrid permanent magnets have been developed. Four different prototypes have been built. All magnets have iron poles and use Samarium Cobalt to provide the magnetic fields. Two use rotating permanent magnetic material to vary the gradient, one uses a sliding shunt to vary the gradient and the fourth uses counter rotating magnets. Preliminary data on gradient strength, temperature stability, and magnetic center position stability are presented. These data are compared to an equivalent electromagnetic prototype

Performance of an Adjustable Strength Permanent Magnet Quadrupole

CERN Document Server

Gottschalk, Stephen C; Kangas, Kenneth; Spencer, Cherrill M; Volk, James T

2005-01-01

An adjustable strength permanent magnet quadrupole suitable for use in Next Linear Collider has been built and tested. The pole length is 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient * length (GL) is 68.7 Tesla. This paper describes measurements of strength, magnetic centerline and field quality made using an air bearing rotating coil system. The magnetic centerline stability during -20% strength adjustment proposed for beam based alignment was < 0.2 microns. Strength hysteresis was negligible. Thermal expansion of quadrupole and measurement parts caused a repeatable and easily compensated change in the vertical magnetic centerline. Calibration procedures as well as centerline measurements made over a wider tuning range of 100% to 20% in strength useful for a wide range of applications will be described. The impact of eddy currents in the steel poles on the magnetic field during strength adjustments will be reported.

Adjustable Permanent Quadrupoles for the Next Linear Collider

International Nuclear Information System (INIS)

Spencer, Cherrill M

2001-01-01

The proposed Next Linear Collider (NLC) will require over 1400 adjustable quadrupoles between the main linacs' accelerator structures. These 12.7 mm bore quadrupoles will have a range of integrated strength from 0.6 to 138 Tesla, with a maximum gradient of 141 Tesla per meter, an adjustment range of +0 to - 20% and effective lengths from 324 mm to 972 mm. The magnetic center must remain stable to within 1 micron during the 20% adjustment. In an effort to reduce costs and increase reliability, several designs using hybrid permanent magnets have been developed. Four different prototypes have been built. All magnets have iron poles and use Samarium Cobalt to provide the magnetic fields. Two use rotating permanent magnetic material to vary the gradient, one uses a sliding shunt to vary the gradient and the fourth uses counter rotating magnets. Preliminary data on gradient strength, temperature stability, and magnetic center position stability are presented. These data are compared to an equivalent electromagnetic prototype

A Tandem-electrostatic-quadrupole for accelerator-based BNCT

International Nuclear Information System (INIS)

Kreiner, A.J.; Kwan, J.W.; Burlon, A.A.; Di Paolo, H.; Henestroza, E.; Minsky, D.M.; Valda, A.A.; Debray, M.E.; Somacal, H.

2007-01-01

A project to develop a Tandem-electrostatic-quadrupole (TESQ) accelerator for accelerator-based boron neutron capture therapy (AB-BNCT) is described. A folded Tandem, with 1.25 MV terminal voltage, combined with an electrostatic quadrupole (ESQ) chain is being proposed. The project goal is a machine capable of delivering 30 mA of 2.5 MeV protons to be used in conjunction with a neutron production target based on the 7 Li(p, n) 7 Be reaction slightly beyond its resonance at 2.25 MeV. This machine is conceptually shown to be capable of accelerating a 30 mA proton beam to 2.5 MeV. These are the specifications needed to produce sufficiently intense and clean epithermal neutron beams, based on the 7 Li(p, n) 7 Be reaction, to perform BNCT treatment for deep-seated tumors in less than an hour. This electrostatic machine is the technologically simplest and cheapest solution for optimized AB-BNCT

Design, fabrication, and calibration of a cryogenic search-coil array for harmonic analysis of quadrupole magnets

International Nuclear Information System (INIS)

Green, M.I.; Barale, P.J.; Hassenzahl, W.V.; Nelson, D.H.; O'Neill, J.W.; Schafer, R.V.; Taylor, C.E.

1987-09-01

A cryogenic search-coil array has been fabricated at LBL for harmonic error analysis of SSC model quadrupoles. It consists of three triplets of coils; the center-coil triplet is 10 cm long, and the end coil triplets are 70 cm long. Design objectives are a high bucking ratio for the dipole and quadrupole signals and utility at cryogenic operating currents (∼6 kA) with sufficient sensitivity for use at room-temperature currents (∼10 A). the design and fabrication are described. Individual coils are mechanically measured to +-5 μm, and their magnetic areas measured to 0.05%. A computer program has been developed to predict the quadrupole and dipole bucking ratios from the mechanical and magnetic measurements. The calibration procedure and accuracy of the array are specified. Results of measurements of SSC model quadrupoles are presented. 1 ref., 4 figs

Synchronization enhancement via an oscillatory bath in a network of ...

Indian Academy of Sciences (India)

2015-02-05

Feb 5, 2015 ... The possibility of using a dynamic environment to achieve and optimize phase synchronization in a network of self-excited cells with free-end boundary conditions is addressed in this paper. The dynamic environment is an oscillatory bath coupled linearly to a network of four cells. The boundaries of the ...

Quadrupole moments of the 12+ isomers in 188Hg and 190Hg

International Nuclear Information System (INIS)

Dracoulis, G.D.; Lonnroth, T.; Vajda, S.; Dafni, E.; Schatz, G.

1984-01-01

The electric quadrupole interaction of the 12 + isomers in 188 Hg and 190 Hg has been measured in solid Hg. The quadrupole moments deduced, vertical strokeQ[ 188 Hg(12 + )]vertical stroke = 91(11) e fm 2 and vertical strokeQ[ 190 Hg(12 + )]vertical stroke = 117(14) e fm 2 suggest a possible change in γ-deformation due to the rotation alignment of the isub(13/2) quasi-neutrons. The temperature dependence of the electric field gradient tensor in Hg was also determined. (orig.)

Oscillatory transenantiomerization of the selected 2-arylpropionic acid (2-APAs) in vitro as a spontaneous phenomenon

International Nuclear Information System (INIS)

Sajewicz, M.; Alska, T.K.

2006-01-01

In this paper, we summarize the results of our earlier investigations on an attempted enantioseparation of the selected 2-arylpropionic acids (2-APAs) by means of the chiral thin layer chromatography (TLC). These results have been originally presented in a series of the research papers published in several chromatography journals. In the current article it was reminded that the prolonged storage of the investigated 2-APAs in the aqueous and the non-aqueous solutions results in an oscillatory change of the respective retardation factor (RF) and the specific rotation (alfa)/sub P/) values. An assumption is introduced as to the chemical nature of the observed phenomenon. It is assumed that the observed oscillations are due to the repeated structural inversion (in our study labelled as oscillatory transenantiomerization) of one enantiomer to its respective antimer. One attempts to at least roughly explain the molecular mechanism of transenantiomerization either by keto-enol tautomerism, or by formation of an intermediate enolic anion, any of these two reaction mechanisms possible only in the basic environment. Then one reflects on the most probable mechanism responsible for the oscillatory nature of the observed structural inversion. It is concluded that the oscillations could be due to an enhanced viscosity of the investigated 2-APA solutions (as compared with those of the respective pure solvents) and/or due to the molecular self-organization within these solutions, resulting in anisotropic properties thereof. Finally, it is concluded that an ultimate explanation of the observed oscillatory transenantiomerization of the selected 2-APAs could probably be offered by the Brusselator-type kinetic model implemented with the diffusion term. In the last section of this paper, argumentation is presented strongly in favour of this particular model and against any alternative speculation as to the supramolecular nature of the observed oscillatory phenomena. (author)

Pulsed-focusing recirculating linacs for muon acceleration

Energy Technology Data Exchange (ETDEWEB)

Johnson, Rolland [Muons, Inc., Batavia, IL (United States)

2014-12-31

Since the muon has a short lifetime, fast acceleration is essential for high-energy applications such as muon colliders, Higgs factories, or neutrino factories. The best one can do is to make a linear accelerator with the highest possible accelerating gradient to make the accelerating time as short as possible. However, the cost of such a single linear accelerator is prohibitively large due to expensive power sources, cavities, tunnels, and related infrastructure. As was demonstrated in the Thomas Jefferson Accelerator Facility (Jefferson Lab) Continuous Electron Beam Accelerator Facility (CEBAF), an elegant solution to reduce cost is to use magnetic return arcs to recirculate the beam through the accelerating RF cavities many times, where they gain energy on each pass. In such a Recirculating Linear Accelerator (RLA), the magnetic focusing strength diminishes as the beam energy increases in a conventional linac that has constant strength quadrupoles. After some number of passes the focusing strength is insufficient to keep the beam from going unstable and being lost. In this project, the use of fast pulsed quadrupoles in the linac sections was considered for stronger focusing as a function of time to allow more successive passes of a muon beam in a recirculating linear accelerator. In one simulation, it was shown that the number of passes could be increased from 8 to 12 using pulsed magnet designs that have been developed and tested. This could reduce the cost of linac sections of a muon RLA by 8/12, where more improvement is still possible. The expense of a greater number of passes and corresponding number of return arcs was also addressed in this project by exploring the use of ramped or FFAG-style magnets in the return arcs. A better solution, invented in this project, is to use combined-function dipole-quadrupole magnets to simultaneously transport two beams of different energies through one magnet string to reduce costs of return arcs by almost a factor of

ELECTRON TRAPPING IN WIGGLER AND QUADRUPOLE MAGNETS OF CESRTA

International Nuclear Information System (INIS)

Wang, Lanfa

2010-01-01

The Cornell Electron Storage Ring (CESR) has been reconfigured as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R and D (1). One of the primary goals of the CesrTA program is to investigate the interaction of the electron cloud with low emittance positron beam to explore methods to suppress the electron cloud, develop suitable advanced instrumentation required for these experimental studies and benchmark predictions by simulation codes. This paper reports the simulation of the electron-cloud formation in the wiggler and quadrupole magnets using the 3D code CLOUDLAND. We found that electrons can be trapped with long lifetime in a quadrupole magnet due to the mirror field trapping mechanism and photoelectrons produced in the wiggler zero field zone have long lifetime due to their complicated trajectory.

Optimization on the end-shaping of a quadrupole magnet

International Nuclear Information System (INIS)

Kumada, M.; Sasaki, H.; Someya, H.; Sakai, I.

1983-01-01

In order to achieve the widest possible aperture of accelerator magnets, end-shaping is a well known method. To do this one has to deal with the three-dimensional fringe field inherent to each geometry. This may be done experimentally by a cut-and-try method or theoretically by a three-dimensional computer code. In any case, considerable time has to be consumed if one wants to get a conclusion which is as general as possible and which is useful in designing magnets. Fringe field optimization on the end-shaping of the conventional quadrupole magnet was done by a cut-and-try method, where a very simple geometry of the end pole was chosen to get a general conclusion. The 'cut-out ratio diagram' given as a conclusion is useful to designers of the conventional quadrupole magnet. (orig.)

Contamination measurements with quadrupole mass spectrometer

International Nuclear Information System (INIS)

Bohatka, S.; Berecz, I.; Langer, G.

1981-01-01

A sensitive quadrupole mass spectrometer of our own construction was used for different purity measurements. The analysis of gases in operating rooms showed a 1 ppm-10 5 ppm concentration of narcotics and helped to develop an effective and cheap method for regenerating narcotic filters. We regularly control the gases used in radioactive pollution measurements by internal GM counters and in radiocarbon dating technique. Combustion products and the gases of a fermenter are investigated for industrial application. (orig.) [de

Assessment of dynamic mechanical properties of the respiratory system during high-frequency oscillatory ventilation*.

Science.gov (United States)

Dellacà, Raffaele L; Zannin, Emanuela; Ventura, Maria L; Sancini, Giulio; Pedotti, Antonio; Tagliabue, Paolo; Miserocchi, Giuseppe

2013-11-01

1) To investigate the possibility of estimating respiratory system impedance (Zrs, forced oscillation technique) by using high-amplitude pressure oscillations delivered during high-frequency oscillatory ventilation; 2) to characterize the relationship between Zrs and continuous distending pressure during an increasing/decreasing continuous distending pressure trial; 3) to evaluate how the optimal continuous distending pressure identified by Zrs relates to the point of maximal curvature of the deflation limb of the quasi-static pressure-volume curve. Prospective laboratory animal investigation. Experimental medicine laboratory. Eight New Zealand rabbits. The rabbits were ventilated with high-frequency oscillatory ventilation. Zrs was measured while continuous distending pressure was increased and decreased between 2 and 26 cm H2O in 1-minute steps of 4 cm H2O. At each step, a low-amplitude (6 cm H2O) sinusoidal signal was alternated with a high-amplitude (18 cm H2O) asymmetric high-frequency oscillatory ventilation square pressure waveform. Pressure-volume curves were determined at the end of the continuous distending pressure trial. All measurements were repeated after bronchoalveolar lavage. Zrs was estimated from flow and pressure measured at the inlet of the tracheal tube and expressed as resistance (Rrs) and reactance (Xrs). Linear correlation between the values, measured by applying the small-amplitude sinusoidal signal and the ventilator waveform, was good for Xrs (r = 0.95 ± 0.04) but not for Rrs (r = 0.60 ± 0.34). Following lavage, the Xrs-continuous distending pressure curves presented a maximum on the deflation limb, identifying an optimal continuous distending pressure that was, on average, 1.1 ± 1.7 cm H2O below the point of maximal curvature of the deflation limb of the pressure-volume curves. Xrs can be accurately measured during high-frequency oscillatory ventilation without interrupting ventilation and/or connecting additional devices. An optimal

An extended magnetic quadrupole lens for a high-resolution nuclear microprobe

Energy Technology Data Exchange (ETDEWEB)

Breese, M.B.H. E-mail: m.breese@surrey.ac.uk; Grime, G.W.; Linford, W.; Harold, M

1999-09-02

This paper describes the design requirements and initial performance of a new style of magnetic quadrupole lens for use in a high-resolution nuclear microprobe, which is presently being constructed in Oxford. Such a microprobe necessitates the use of a small image distance from the exit face of the final quadrupole lens to the image plane in order to produce a large demagnification. This means that the final lens should be as close to the sample chamber as possible. However, with conventional magnetic quadrupoles the current-carrying coils protrude by a typical distance of 10-20 mm beyond the pole face, thereby significantly limiting the minimum image distance. The approach taken here is to recess the coils into the body of the lens, so that they are almost flush with the pole pieces and lens yoke, enabling an image distance of 55 mm. Three-dimensional magnetic field calculations within this lens structure predict that the field in the extended pole piece 'nose' region is only slightly less than that in the main lens body. Experimental field profiles, measured using a Hall probe, are used to confirm these calculations.

An extended magnetic quadrupole lens for a high-resolution nuclear microprobe

International Nuclear Information System (INIS)

Breese, M.B.H.; Grime, G.W.; Linford, W.; Harold, M.

1999-01-01

This paper describes the design requirements and initial performance of a new style of magnetic quadrupole lens for use in a high-resolution nuclear microprobe, which is presently being constructed in Oxford. Such a microprobe necessitates the use of a small image distance from the exit face of the final quadrupole lens to the image plane in order to produce a large demagnification. This means that the final lens should be as close to the sample chamber as possible. However, with conventional magnetic quadrupoles the current-carrying coils protrude by a typical distance of 10-20 mm beyond the pole face, thereby significantly limiting the minimum image distance. The approach taken here is to recess the coils into the body of the lens, so that they are almost flush with the pole pieces and lens yoke, enabling an image distance of 55 mm. Three-dimensional magnetic field calculations within this lens structure predict that the field in the extended pole piece 'nose' region is only slightly less than that in the main lens body. Experimental field profiles, measured using a Hall probe, are used to confirm these calculations

Quadrupole Moments And Gamma Deformation Of Wobbling Excitations In 163Ln

International Nuclear Information System (INIS)

Goergen, A.; Hagemann, G.B.; Sletten, G.; Hamamoto, I.; Bengtsson, R.; Clark, R.M.; Cromaz, M.; Fallon, P.; Lee, I.Y.; Macchiavelli, A.O.; Ward, D.; Huebel, H.

2005-01-01

Wobbling is an excitation mode unique to triaxial nuclei. Even though it is a general consequence of triaxiality in nuclei, it has so far only been observed in the odd-mass Lu isotopes around 163Lu. The principal evidence for the wobbling mode is based on the pattern of rotational bands characterized and described by a wobbling phonon number and the decay between different bands belonging to the same family. A new measurement revealed lifetimes of states in an excited wobbling band for the first time and gave access to absolute transition probabilities for both in-band and interband transitions. A general recipe how to derive quadrupole moments for triaxial nuclei from experimental data is discussed. The results show a remarkable similarity of the quadrupole moments for the different bands, further supporting the wobbling scenario. A decrease of the quadrupole moments is observed with increasing spin. This is attributed to an increase in triaxiality with spin, which can at the same time explain the dependence of the interband transitions on spin. Such an increase in triaxiality is qualitatively reproduced by cranking calculations to which the experimental results are compared

Finite-size scaling for quantum chains with an oscillatory energy gap

International Nuclear Information System (INIS)

Hoeger, C.; Gehlen, G. von; Rittenberg, V.

1984-07-01

We show that the existence of zeroes of the energy gap for finite quantum chains is related to a nonvanishing wavevector. Finite-size scaling ansaetze are formulated for incommensurable and oscillatory structures. The ansaetze are verified in the one-dimensional XY model in a transverse field. (orig.)

Measurement of transmitted power in untapered multifibre unions oscillatory spectral behaviour

OpenAIRE

Rodriguez Horche, Paloma; Muriel Fernández, Miguel Ángel; Martín Pereda, José Antonio

1989-01-01

Shows a new structure, the untapered multifibre union, with similar oscillation behaviour to that of tapered single-mode fibres. As a consequences conical regions are not relevant to the final results. This oscillatory behaviour opens the way to low-cost all-fibre devices such as optical filters

Brain Oscillatory Correlates of Altered Executive Functioning in Positive and Negative Symptomatic Schizophrenia Patients and Healthy Controls.

Science.gov (United States)

Berger, Barbara; Minarik, Tamas; Griesmayr, Birgit; Stelzig-Schoeler, Renate; Aichhorn, Wolfgang; Sauseng, Paul

2016-01-01

Working Memory and executive functioning deficits are core characteristics of patients suffering from schizophrenia. Electrophysiological research indicates that altered patterns of neural oscillatory mechanisms underpinning executive functioning are associated with the psychiatric disorder. Such brain oscillatory changes have been found in local amplitude differences at gamma and theta frequencies in task-specific cortical areas. Moreover, interregional interactions are also disrupted as signified by decreased phase coherence of fronto-posterior theta activity in schizophrenia patients. However, schizophrenia is not a one-dimensional psychiatric disorder but has various forms and expressions. A common distinction is between positive and negative symptomatology but most patients have both negative and positive symptoms to some extent. Here, we examined three groups-healthy controls, predominantly negative, and predominantly positive symptomatic schizophrenia patients-when performing a working memory task with increasing cognitive demand and increasing need for executive control. We analyzed brain oscillatory activity in the three groups separately and investigated how predominant symptomatology might explain differences in brain oscillatory patterns. Our results indicate that differences in task specific fronto-posterior network activity (i.e., executive control network) expressed by interregional phase synchronization are able to account for working memory dysfunctions between groups. Local changes in the theta and gamma frequency range also show differences between patients and healthy controls, and more importantly, between the two patient groups. We conclude that differences in oscillatory brain activation patterns related to executive processing can be an indicator for positive and negative symptomatology in schizophrenia. Furthermore, changes in cognitive and especially executive functioning in patients are expressed by alterations in a task-specific fronto

Power System Oscillatory Behaviors: Sources, Characteristics, & Analyses

Energy Technology Data Exchange (ETDEWEB)

Follum, James D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tuffner, Francis K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Dosiek, Luke A. [Union College, Schenectady, NY (United States); Pierre, John W. [Univ. of Wyoming, Laramie, WY (United States)

2017-05-17

This document is intended to provide a broad overview of the sources, characteristics, and analyses of natural and forced oscillatory behaviors in power systems. These aspects are necessarily linked. Oscillations appear in measurements with distinguishing characteristics derived from the oscillation’s source. These characteristics determine which analysis methods can be appropriately applied, and the results from these analyses can only be interpreted correctly with an understanding of the oscillation’s origin. To describe oscillations both at their source within a physical power system and within measurements, a perspective from the boundary between power system and signal processing theory has been adopted.

Beam-based alignment and tuning procedures for e+e- collider final focus systems

International Nuclear Information System (INIS)

Bulos, F.; Burke, D.; Helm, R.; Irwin, J.; Odian, A.; Roy, G.; Ruth, R.; Yamamoto, N.

1991-05-01

For future linear colliders, with very small emittances and beam sizes and demanding tolerances on final focus system alignment and magnet errors, it becomes increasingly important to use the beam as a diagnostic tool. We report here procedures we have identified and will be implemented in the Final Focus Test Beam at SLAC incorporating (1) quadrupole strength changes, (2) central orbit modifications, (3) spot size measurements, and (4) beam stability monitoring. 3 refs., 4 figs., 3 tabs

AE monitoring instrumentation for high performance superconducting dipoles and quadrupoles, Phase 2

Science.gov (United States)

Iwasa, Y.

1986-01-01

In the past year and a half, attention has been focused on the development of instrumentation for on-line monitoring of high-performance superconducting dipoles and quadrupoles. This instrumentation has been completed and satisfactorily demonstrated on a prototype Fermi dipole. Conductor motion is the principal source of acoustic emission (AE) and the major cause of quenches in the dipole, except during the virgin run when other sources are also present. The motion events are mostly microslips. The middle of the magnet is most susceptible to quenches. This result agrees with the peak field location in the magnet. In the virgin state the top and bottom of the magnet appeared acoustically similar but diverged after training, possibly due to minute structural asymmetry, for example differences in clamping and welding strength; however, the results do not indicate any major structural defects. There is good correlation between quench current and AE starting current. The correlation is reasonable if mechanical disturbances are indeed responsible for quench. Based on AE cumulative history, the average frictional power dissipation in the whole dipole winding is estimated to be approx. 10 (MU)W cm(-3). We expect to implement the following in the next phase of this project: Application of room-temperature techniques to detecting structural defects in the dipole; application of the system to other dipoles and quadrupoles in the same series to compare their performances; and further investigation of AE starting current approx. quench current relationship. Work has begun on the room temperature measurements. Preliminary Stress Wave Factor measurements have been made on a model dipole casing.

Oscillatory brain activity in spontaneous and induced sleep stages in flies.

Science.gov (United States)

Yap, Melvyn H W; Grabowska, Martyna J; Rohrscheib, Chelsie; Jeans, Rhiannon; Troup, Michael; Paulk, Angelique C; van Alphen, Bart; Shaw, Paul J; van Swinderen, Bruno

2017-11-28

Sleep is a dynamic process comprising multiple stages, each associated with distinct electrophysiological properties and potentially serving different functions. While these phenomena are well described in vertebrates, it is unclear if invertebrates have distinct sleep stages. We perform local field potential (LFP) recordings on flies spontaneously sleeping, and compare their brain activity to flies induced to sleep using either genetic activation of sleep-promoting circuitry or the GABA A agonist Gaboxadol. We find a transitional sleep stage associated with a 7-10 Hz oscillation in the central brain during spontaneous sleep. Oscillatory activity is also evident when we acutely activate sleep-promoting neurons in the dorsal fan-shaped body (dFB) of Drosophila. In contrast, sleep following Gaboxadol exposure is characterized by low-amplitude LFPs, during which dFB-induced effects are suppressed. Sleep in flies thus appears to involve at least two distinct stages: increased oscillatory activity, particularly during sleep induction, followed by desynchronized or decreased brain activity.

Design and fabrication of Radio Frequency Quadrupole (RFQ) Accelerator at IUAC, New Delhi

International Nuclear Information System (INIS)

Ahuja, R.; Kothari, A.; Safvan, C.P.; Kumar, Sugam; Ram Sankar, P.

2013-01-01

As part of the accelerator augmentation program at Inter-University Accelerator Centre (IUAC), a high current injector (HCI) is being developed to inject high currents of highly charged ions into the superconducting LINAC. The ion beams produced by the Electron Cyclotron Resonance (ECR) based PKDELIS ion source will be injected into a Radio Frequency Quadrupole Accelerator (RFQ). The RFQ focuses and accelerates the ion beam. For the development of the RFQ Accelerator, a prototype of nearly half length was successfully built at IUAC to test the RF, thermal and mechanical design. The prototype is designed for 30 kW power at 48.5 MHz. This paper presents the mechanical design, fabrication and assembly of the final 2.5 m long RFQ. (author)

Working memory load related modulations of the oscillatory brain activity. N-back ERD/ERS study

International Nuclear Information System (INIS)

Nakao, Yoshiaki; Tamura, Toshiyo; Kodabashi, Atsushi; Fujimoto, Toshiro; Yarita, Masaru

2011-01-01

In recent cognitive neuroscience, a lot of studies of the human working memory were examined, and electroencephalography (EEG) measurements during n-back task were often used. However, they were almost studied by event related potentials (ERP) analysis. In the ERP study, time-locked components can be elicited, but non time-locked components such as the modulated brain oscillatory activity might be lost by an averaging procedure. To elucidate the contribution of the modulations of the brain oscillatory activity to the human working memory, we examined event related desynchronization (ERD)/event related synchronization (ERS) analysis on the source waveforms during n-back task. Source waveforms were calculated from a source model which was constructed with the sources seeded from fMRI meta-analysis of n-back task and additional sources in the orbitofrontal cortex and the visual cortex estimated with P100 and P360 components in the n-back ERP. Our results suggested the network which included the prefrontal cortex and the parietal lobe had a contribution to human working memory process, and it was mediated by theta oscillatory activity. (author)

Low-field permanent magnet quadrupoles in a new relativistic-klystron two-beam accelerator design

Energy Technology Data Exchange (ETDEWEB)

Yu, S.; Sessler, A. [Lawrence Berkeley Lab., CA (United States)

1995-02-01

Permanent magnets play a central role in the new relativistic klystron two-beam-accelerator design. The two key goals of this new design, low cost and the suppression of beam break-up instability are both intimately tied to the permanent magnet quadrupole focusing system. A recently completed systems study by a joint LBL-LLNL team concludes that a power source for a 1 TeV center-of-mass Next Linear Collider based on the new TBA design can be as low as $1 billion, and the efficiency (wall plug to rf) is estimated to be 36%. End-to-end simulations of longitudinal and transverse beam dynamics show that the drive beam is stable over the entire TBA unit.

Hydrogen isotope analysis by quadrupole mass spectrometry

International Nuclear Information System (INIS)

Ellefson, R.E.; Moddeman, W.E.; Dylla, H.F.

1981-03-01

The analysis of isotopes of hydrogen (H, D, T) and helium ( 3 He, 4 He) and selected impurities using a quadrupole mass spectrometer (QMS) has been investigated as a method of measuring the purity of tritium gas for injection into the Tokamak Fusion Test Reactor (TFTR). A QMS was used at low resolution, m/Δm 3 He, and 4 He in HT/D 2

Direct trace analysis of metals and alloys in a quadrupole ion-trap mass spectrometer

CERN Document Server

Song, K S; Yang, M; Cha, H K; Lee, J M; Lee, G H

1999-01-01

An ion-trap mass spectrometer adopting a quadrupole ion-trap and laser ablation/ionization method was constructed. The developed system was tested for composition analysis of some metals (Cu, stainless), and alloys (hastalloy C, mumetal) by mass spectrometry. Samples were analyzed by using laser ablation from a sample probe tip followed by a mass analysis with the quadrupole ion-trap. The quadrupole ion-trap was modified to enable laser ablation by a XeCl excimer laser pulse that passed radially through the ring electrode. A mass scan of the produced ions was performed in the mass selective instability mode wherein trapped ions were successively detected by increasing the rf voltage through the ring electrode. Factors affecting the mass resolution, such as pressure of buffer gas and ablation laser power, are discussed.

Drive Beam Quadrupoles for the CLIC Project: a Novel Method of Fiducialisation and a New Micrometric Adjustment System

CERN Document Server

AUTHOR|(SzGeCERN)411678; Duquenne, Mathieu; Sandomierski, Jacek; Sosin, Mateusz; Rude, Vivien

2014-01-01

This paper presents a new method of fiducialisation applied to determine the magnetic axis of the Drive Beam quadrupole of the CLIC project with respect to external alignment fiducials, within a micrometric accuracy and precision. It introduces also a new micrometric adjustment system along 5 Degrees of Freedom, developed for the same Drive Beam quadrupole. The combination of both developments opens very interesting perspectives to get a more simple and accurate alignment of the quadrupoles.

Identifying the Oscillatory Mechanism of the Glucose Oxidase-Catalase Coupled Enzyme System.

Science.gov (United States)

Muzika, František; Jurašek, Radovan; Schreiberová, Lenka; Radojković, Vuk; Schreiber, Igor

2017-10-12

We provide experimental evidence of periodic and aperiodic oscillations in an enzymatic system of glucose oxidase-catalase in a continuous-flow stirred reactor coupled by a membrane with a continuous-flow reservoir supplied with hydrogen peroxide. To describe such dynamics, we formulate a detailed mechanism based on partial results in the literature. Finally, we introduce a novel method for estimation of unknown kinetic parameters. The method is based on matching experimental data at an oscillatory instability with stoichiometric constraints of the mechanism formulated by applying the stability theory of reaction networks. This approach has been used to estimate rate coefficients in the catalase part of the mechanism. Remarkably, model simulations show good agreement with the observed oscillatory dynamics, including apparently chaotic intermittent behavior. Our method can be applied to any reaction system with an experimentally observable dynamical instability.

Analysis of current-driven oscillatory dynamics of single-layer homoepitaxial islands on crystalline conducting substrates

Science.gov (United States)

Dasgupta, Dwaipayan; Kumar, Ashish; Maroudas, Dimitrios

2018-03-01

We report results of a systematic study on the complex oscillatory current-driven dynamics of single-layer homoepitaxial islands on crystalline substrate surfaces and the dependence of this driven dynamical behavior on important physical parameters, including island size, substrate surface orientation, and direction of externally applied electric field. The analysis is based on a nonlinear model of driven island edge morphological evolution that accounts for curvature-driven edge diffusion, edge electromigration, and edge diffusional anisotropy. Using a linear theory of island edge morphological stability, we calculate a critical island size at which the island's equilibrium edge shape becomes unstable, which sets a lower bound for the onset of time-periodic oscillatory dynamical response. Using direct dynamical simulations, we study the edge morphological dynamics of current-driven single-layer islands at larger-than-critical size, and determine the actual island size at which the migrating islands undergo a transition from steady to time-periodic asymptotic states through a subcritical Hopf bifurcation. At the highest symmetry of diffusional anisotropy examined, on {111} surfaces of face-centered cubic crystalline substrates, we find that more complex stable oscillatory states can be reached through period-doubling bifurcation at island sizes larger than those at the Hopf points. We characterize in detail the island morphology and dynamical response at the stable time-periodic asymptotic states, determine the range of stability of these oscillatory states terminated by island breakup, and explain the morphological features of the stable oscillating islands on the basis of linear stability theory.

Quenching of spin-flip quadrupole transitions

International Nuclear Information System (INIS)

Castel, B.; Blunden, P.; Okuhara, Y.

1985-01-01

An increasing amount of experimental data indicates that spin-flip quadrupole transitions exhibit quenching effects similar to those reported earlier in (p,n) reactions involving l = 0 and l = 1 transitions. We present here two model calculations suggesting that the E2 spin-flip transitions are more affected than their M1 and M3 counterparts by the tensor and spin-orbit components of the nuclear force and should exhibit the largest quenching. We also review the experimental evidence corroborating our observations

Effect of a serrated trailing edge on sound radiation from nearby quadrupoles.

Science.gov (United States)

Karimi, Mahmoud; Croaker, Paul; Kinns, Roger; Kessissoglou, Nicole

2017-05-01

A periodic boundary element technique is implemented to study the noise reduction capability of a plate with a serrated trailing edge under quadrupole excitation. It is assumed for this purpose that the quadrupole source tensor is independent of the trailing edge configuration and that the effect of the trailing edge shape is to modify sound radiation from prescribed boundary layer sources. The flat plate is modelled as a continuous structure with a finite repetition of small spanwise segments. The matrix equation formulated by the periodic boundary element method for this 3D acoustic scattering problem is represented as a block Toeplitz matrix. The discrete Fourier transform is employed in an iterative algorithm to solve the block Toeplitz system. The noise reduction mechanism for a serrated trailing edge in the near field is investigated by comparing contour plots obtained from each component of the quadrupole for unserrated and serrated trailing edge plate models. The noise reduction due to the serrated trailing edge is also examined as a function of the source location.

Stabilisation and precision pointing quadrupole magnets in the Compact Linear Collider (CLIC)

CERN Document Server

Janssens, Stef; Linde, Frank; van den Brand, Jo; Bertolini, Alessandro; Artoos, Kurt

This thesis describes the research done to provide stabilisation and precision positioning for the main beam quadrupole magnets of the Compact Linear Collider CLIC. The introduction describes why new particle accelerators are needed to further the knowledge of our universe and why they are linear. A proposed future accelerator is the Compact Linear Collider (CLIC) which consists of a novel two beam accelerator concept. Due to its linearity and subsequent single pass at the interaction point, this new accelerator requires a very small beam size at the interaction point, in order to increase collision effectiveness. One of the technological challenges, to obtain these small beam sizes at the interaction point, is to keep the quadrupole magnets aligned and stable to 1.5 nm integrated r.m.s. in vertical and 5 nm integrated root mean square (r.m.s.) in lateral direction. Additionally there is a proposal to create an intentional offset (max. 50 nm every 20 ms with a precision of +/- 1 nm), for several quadrupole ma...

Design and fabrication of the prototype superconducting tuning quadrupole and octupole correction winding for the LHC project

International Nuclear Information System (INIS)

Perin, R.; Siegel, N.; Bidaurrazaga, H.; Garcia Tabares, L.

1992-01-01

CERN is preparing for the construction of the Large Hadron Collider (LHC) to be installed in the LEP tunnel. The magnetic lattice of the LHC will consist of a ring of twin aperture dipoles and quadrupoles, connected electrically in series. To adjust the working point of the machine, so called tuning quadrupoles will be installed in pairs in each regular cell, next to the main quadrupoles. Also, to correct multipolar field errors in the LHC, an octupole correction winding is required near each lattice quadrupole. A nested construction of these two magnets is foreseen. As part of the LHC R and D program, CERN and ACICA (a group of five Spanish industries: Abengoz, Canzler, Indar, Cenemesa and AME; since June 1990 Cenemesa is part of ABB Spain), signed a common development agreement for the design, fabrication and testing of a prototype tuning quadrupole and octupole corrector. This paper describes the design of these magnets, giving details of magnetic and mechanical calculations, including results from existing and specially developed computer codes, and model work. Further, the construction procedures are described, including the facilities and tooling developed by ACICA for this work

Brain oscillatory substrates of visual short-term memory capacity.

Science.gov (United States)

Sauseng, Paul; Klimesch, Wolfgang; Heise, Kirstin F; Gruber, Walter R; Holz, Elisa; Karim, Ahmed A; Glennon, Mark; Gerloff, Christian; Birbaumer, Niels; Hummel, Friedhelm C

2009-11-17

The amount of information that can be stored in visual short-term memory is strictly limited to about four items. Therefore, memory capacity relies not only on the successful retention of relevant information but also on efficient suppression of distracting information, visual attention, and executive functions. However, completely separable neural signatures for these memory capacity-limiting factors remain to be identified. Because of its functional diversity, oscillatory brain activity may offer a utile solution. In the present study, we show that capacity-determining mechanisms, namely retention of relevant information and suppression of distracting information, are based on neural substrates independent of each other: the successful maintenance of relevant material in short-term memory is associated with cross-frequency phase synchronization between theta (rhythmical neural activity around 5 Hz) and gamma (> 50 Hz) oscillations at posterior parietal recording sites. On the other hand, electroencephalographic alpha activity (around 10 Hz) predicts memory capacity based on efficient suppression of irrelevant information in short-term memory. Moreover, repetitive transcranial magnetic stimulation at alpha frequency can modulate short-term memory capacity by influencing the ability to suppress distracting information. Taken together, the current study provides evidence for a double dissociation of brain oscillatory correlates of visual short-term memory capacity.

Numerical calculation of a class of highly oscillatory integrals with the Mathieu function

International Nuclear Information System (INIS)

Long Yongxing

1992-01-01

The author describes a method for computing highly oscillatory integrals with the Mathieu function. The practice proves that not only the results are highly satisfactory, but also the method is time-saving

Quadrupole moments of low-lying baryons with spin

Indian Academy of Sciences (India)

The chiral constituent quark model ( CQM) with general parametrization (GP) method has been formulated to calculate the quadrupole moments of the spin − 3 2 + decuplet baryons and spin − 3 2 + → 1 2 + transitions. The implications of such a model have been investigated in detail for the effects of symmetry breaking ...

Simple expressions of the nuclear relaxation rate enhancement due to quadrupole nuclei in slowly tumbling molecules

Energy Technology Data Exchange (ETDEWEB)

Fries, Pascal H., E-mail: pascal-h.fries@cea.fr [Université Grenoble Alpes, INAC-SCIB, RICC, F-38000 Grenoble (France); CEA, INAC-SCIB, RICC, F-38000 Grenoble (France); Belorizky, Elie [Université Grenoble Alpes, LIPHY, F-38000 Grenoble (France); CEA, Leti-Clinatec, F-38000 Grenoble (France)

2015-07-28

For slowly tumbling entities or quasi-rigid lattices, we derive very simple analytical expressions of the quadrupole relaxation enhancement (QRE) of the longitudinal relaxation rate R{sub 1} of nuclear spins I due to their intramolecular magnetic dipolar coupling with quadrupole nuclei of arbitrary spins S ≥ 1. These expressions are obtained by using the adiabatic approximation for evaluating the time evolution operator of the quantum states of the quadrupole nuclei S. They are valid when the gyromagnetic ratio of the spin S is much smaller than that of the spin I. The theory predicts quadrupole resonant peaks in the dispersion curve of R{sub 1} vs magnetic field. The number, positions, relative intensities, Lorentzian shapes, and widths of these peaks are explained in terms of the following properties: the magnitude of the quadrupole Hamiltonian and the asymmetry parameter of the electric field gradient (EFG) acting on the spin S, the S-I inter-spin orientation with respect to the EFG principal axes, the rotational correlation time of the entity carrying the S–I pair, and/or the proper relaxation time of the spin S. The theory is first applied to protein amide protons undergoing dipolar coupling with fast-relaxing quadrupole {sup 14}N nuclei and mediating the QRE to the observed bulk water protons. The theoretical QRE agrees well with its experimental counterpart for various systems such as bovine pancreatic trypsin inhibitor and cartilages. The anomalous behaviour of the relaxation rate of protons in synthetic aluminium silicate imogolite nano-tubes due to the QRE of {sup 27}Al (S = 5/2) nuclei is also explained.

Adjustable Permanent Quadrupoles Using Rotating Magnet Material Rods for the Next Linear Collider.

CERN Document Server

Spencer, C M

2002-01-01

The proposed Next Linear Collider (NLC) will require over 1400 adjustable quadrupoles between the main linacs' accelerator structures. These 12.7 mm bore quadrupoles will have a range of integrated strength from 0.6 to 132 Tesla, with a maximum gradient of 135 Tesla per meter, an adjustment range of +0 -20% and effective lengths from 324 mm to 972 mm. The magnetic center must remain stable to within 1 micrometer during the 20% adjustment. In an effort to reduce estimated costs and increase reliability, several designs using hybrid permanent magnets have been developed. All magnets have iron poles and use either Samarium Cobalt or Neodymium Iron to provide the magnetic fields. Two prototypes use rotating rods containing permanent magnetic material to vary the gradient. Gradient changes of 20% and center shifts of less than 20 microns have been measured. These data are compared to an equivalent electromagnet prototype. See High Reliability Prototype Quadrupole for the Next Linear Collider by C.E Rago, C.M SPENC...

The gravitational polarization in general relativity: solution to Szekeres' model of quadrupole polarization

International Nuclear Information System (INIS)

Montani, Giovanni; Ruffini, Remo; Zalaletdinov, Roustam

2003-01-01

A model for the static weak-field macroscopic medium is analysed and the equation for the macroscopic gravitational potential is derived. This is a biharmonic equation which is a non-trivial generalization of the Poisson equation of Newtonian gravity. In the case of strong gravitational quadrupole polarization, it essentially holds inside a macroscopic matter source. Outside the source the gravitational potential fades away exponentially. The equation is equivalent to a system of the Poisson equation and the non-homogeneous modified Helmholtz equations. The general solution to this system is obtained by using the Green function method and it is not limited to Newtonian gravity. In the case of insignificant gravitational quadrupole polarization, the equation for macroscopic gravitational potential becomes the Poisson equation with the matter density renormalized by a factor including the value of the quadrupole gravitational polarization of the source. The general solution to this equation obtained by using the Green function method is limited to Newtonian gravity

A united phenomenological description of quadrupole excitations in even-even nuclei

International Nuclear Information System (INIS)

Lipas, P.O.; Haapakoski, P.; Honkaranta, T.

1975-05-01

A phenomenological model is developed for the collective quadrupole properties of all even-even nuclei. Rotational, vibrational, and transitional nuclei are included in the model on an equal footing. A Bohr-type intrinsic Hamiltonian for harmonic quadrupole vibrations about an axially deformed shape is solved exactly. States of good angular momentum are projected out of the intrinsic states, and they are made orthogonal by a Schmidt scheme. The angular-momentum and phonon-number composition of the states is analyzed at various stages; states with K=1 are found spurious. Excitation energies for the ground, β and γ bands are calculated as expectation values of a radically simplified nuclear Hamiltonian in our projected and orthogonalized states. With increasing deformation the calculated energies evolve smoothly from the evenly spaced phonon spectrum to the Bohr-Mottelson rotational-vibrational spectrum according to the scheme of Sheline and Sakai. The basic model contains only two parameters (deformation d and energy scale) to fix the entire quadrupole spectrum of a nucleus. The results are given in the form of graphs suitable for immediate application; numerical results are readily produced by our computer code. The ground bands are fitted comparably to the VMI model, while the β and γ bands are reproduced qualitatively. The nuclei 152 Sm, 152 Gd, and 114 Cd are used as test cases. Quadrupole moments and E2 transition rates are also calculated. Intra-ground-band transition ratios and branching ratios from the β and γ bands are given in terms of the single parameter d. The results are applied to 152 Sm, with fair success. Finally the model to include two more parameters (anisotropy) is extended. The improvement over the basic model is modest in view of added parameters and computational effort. (author)

Determination of crystal oscillatory spectra by internal friction data spectroscopic analysis

International Nuclear Information System (INIS)

Zaykin, Yu.A.

1998-01-01

Technique for relaxation spectra determination on the basis of internal friction averaging over relaxation frequencies is developed. It is shown that mathematically the problem is reduced to solution of the first type Fredholm integral equation. Impurity oscillatory spectra in alpha-iron, molybdenum and Fe-Cr-Ni alloy are obtained. (author)

Phase lags in oscillatory sheet flow: experiments and bed load modelling

NARCIS (Netherlands)

Dohmen-Janssen, Catarine M.; Kroekenstoel, D.F.; Kroekenstoel, D.F.; Hassan, Wael; Ribberink, Jan S.

2002-01-01

Sheet flow corresponds to the high velocity regime when small bed ripples are washed out and sand is transported in a thin layer close to the bed. Therefore, it is often assumed that sand transport in oscillatory sheet flow behaves quasi-steady: time-dependent transport rates are assumed to be

Macroscopic description of normal quadrupole oscillations and shape of rotating nuclei (spheroids)

International Nuclear Information System (INIS)

Balbutsev, E.B.; Mikhailov, I.N.; Vaishvila, Z.

1981-01-01

The ''distorted-Fermi-surface'' model is generalized to study the rotating nuclei. The mathematical problems of the model are solved with the help of the tensor virial method by Chandrasekhar-Lebovitz. The parameters of a form and characteristic frequencies of the quadrupole oscillations are calculated as a function of angular velocity Ω for the rotating nuclei. The energy of Giant Quadrupole Resonance is in agreement with experiment for Ω=0. There are two low-lying modes of oscillations in the model. The critical angular momenta are calculated. The comparison with the liquid drop model is done [ru

Summary of the working group on high current transport and final focus lenses

International Nuclear Information System (INIS)

Garren, A.A.

1978-09-01

The group reviewed recent work, and then addressed itself to relating the current understanding of relevant beam transport effects to the four reference concepts. In addition there was discussion on plans for future experimental and theoretical work. Discussions covered the following topics: (1) Transverse instabilities on intense beams through periodic focusing systems, (2) evaluation and correction of chromatic aberrations in the final beam transport lines, (3) evaluation and correction of geometric aberrations due to quadrupole fringe fields, and (4) ion focusing by electrons

Dopaminergic modulation of the spectral characteristics in the rat brain oscillatory activity

International Nuclear Information System (INIS)

Valencia, Miguel; López-Azcárate, Jon; Nicolás, María Jesús; Alegre, Manuel; Artieda, Julio

2012-01-01

Highlights: ► The oscillatory activity recorded at different locations of the rat brain present a power law characteristic (PLC). ► Dopaminergic drugs are able to modify the power law spectral characteristic of the oscillatory activity. ► Drugs with opposite effects over the dopaminergic system (agonists/antagonists), induce opposite changes in the PLC. ► There is a fulcrum point for the modulation of the PLC around 20 Hz. ► The brain operates in a state of self-organized criticality (SOC) sensitive to dopaminergic modulation. - Abstract: Oscillatory activity can be widely recorded in the brain. It has been demonstrated to play an important role not only in the physiology of movement, perception and cognition, but also in the pathophysiology of a variety of diseases. In frequency domain, neurophysiological recordings show a power spectrum (PSD) following a log (PSD) ∝ log (f) −β , that reveals an intrinsic feature of many complex systems in nature: the presence of a scale-free dynamics characterized by a power-law component (PLC). Here we analyzed the influence of dopaminergic drugs over the PLC of the oscillatory activity recorded from different locations of the rat brain. Dopamine (DA) is a neurotransmitter that is required for a number of physiological functions like normal feeding, locomotion, posturing, grooming and reaction time. Alterations in the dopaminergic system cause vast effects in the dynamics of the brain activity, that may be crucial in the pathophysiology of neurological (like Parkinson’s disease) or psychiatric (like schizophrenia) diseases. Our results show that drugs with opposite effects over the dopaminergic system, induce opposite changes in the characteristics of the PLC: DA agonists/antagonists cause the PLC to swing around a fulcrum point in the range of 20 Hz. Changes in the harmonic component of the spectrum were also detected. However, differences between recordings are better explained by the modulation of the PLC

SU(6) quadrupole phonon model for even and odd nuclei and the SU(3) limit

Energy Technology Data Exchange (ETDEWEB)

Paar, V; Brant, S [Zagreb Univ. (Yugoslavia). Prirodoslovno Matematicki Fakultet; Canto, L F [Rio de Janeiro Univ. (Brazil). Inst. de Fisica; Leander, G [Lund Inst. of Tech. (Sweden). Dept. of Mathematical Physics; Oak Ridge National Lab., TN (USA)); Vouk, M [Zagreb Univ. (Yugoslavia). Computing Centre SRCE

1982-04-05

Analogous to the equivalence between the SU(6) quadrupole-phonon model (TQM) and the interacting boson model (IBM), the equivalence is pointed out for odd systems between the SU(6) particle quadrupole-phonon coupling model (PTQM) and the interacting boson-fermion model (IBFM). PTQM is formulated starting from the Dyson representation for the odd system. Different aspects of the SU(3) limit of TQM and PTQM are studied; the quadrupole-phonon block structure of rotational bands in even and odd nuclei and analytic expressions based on the coherent state; signature effects generated in PTQM; electromagnetic properties and correction factors for PTQM; overlaps of the PTQM analogs of Nilsson states with Coriolis-coupled Nilsson states and the relation to the rotational model representation.

High-throughput shotgun lipidomics by quadrupole time-of-flight mass spectrometry

DEFF Research Database (Denmark)

Ståhlman, Marcus; Ejsing, Christer S.; Tarasov, Kirill

2009-01-01

Technological advances in mass spectrometry and meticulous method development have produced several shotgun lipidomic approaches capable of characterizing lipid species by direct analysis of total lipid extracts. Shotgun lipidomics by hybrid quadrupole time-of-flight mass spectrometry allows...... the absolute quantification of hundreds of molecular glycerophospholipid species, glycerolipid species, sphingolipid species and sterol lipids. Future applications in clinical cohort studies demand detailed lipid molecule information and the application of high-throughput lipidomics platforms. In this review...... we describe a novel high-throughput shotgun lipidomic platform based on 96-well robot-assisted lipid extraction, automated sample infusion by mircofluidic-based nanoelectrospray ionization, and quantitative multiple precursor ion scanning analysis on a quadrupole time-of-flight mass spectrometer...

Ion beam properties after mass filtering with a linear radiofrequency quadrupole

International Nuclear Information System (INIS)

Ferrer, R.; Kwiatkowski, A.A.; Bollen, G.; Lincoln, D.L.; Morrissey, D.J.; Pang, G.K.; Ringle, R.; Savory, J.; Schwarz, S.

2014-01-01

The properties of ion beams passing through a linear radiofrequency quadrupole mass filter were investigated with special attention to their dependence on the mass resolving power. Experimentally, an increase of the transverse emittance was observed as the mass-to-charge selectivity of the mass filter was raised. The experimental behavior was confirmed by beam transport simulations. -- Highlights: • The ion-optical properties of a Quadrupole Mass Filter (QMF) are presented. • Measured beam emittances follow a trend to larger values for smaller A/Q ratios and increasing mass resolution. • The experimental behavior was confirmed by beam transport simulations. • The use of a QMF for mass filtering comes at the cost of emittance growth of the ion beam

Quench protection of the LHC inner triplet quadrupoles built at Fermilab

CERN Document Server

Bauer, P; Chiesa, L; Di Marco, J; Fehér, S; Lamm, M J; McInturff, A D; Nobrega, A; Orris, D; Tartaglia, M; Tompkins, J C; Zlobin, A V

2001-01-01

High gradient quadrupoles are being developed by the US-LHC Accelerator project for the LHC interaction region inner triplets. These 5.5 m long magnets have a single 70 mm aperture and operate in superfluid helium at a peak gradient of 215 T/m. Through the construction and test of eight 2 meter long model quadrupoles, strip heaters of various geometries and insulation thicknesses have proven to be effective in protecting the magnets from excessively high coil temperatures and coil voltages to ground. This paper reports on the results of the model program to optimize the heater performance within the context of the LHC inner triplet electrical power and quench detection scheme. (6 refs).

Dynamical interplay between pairing and quadrupole correlations in odd-mass nuclei

International Nuclear Information System (INIS)

Kaneko, Kazunari; Takada, Kenjiro; Sakata, Fumihiko; Tazaki, Shigeru.

1982-01-01

Study of the dynamical interplay between pairing and quadrupole correlations in odd-mass nuclei has been developed. One of the purposes of this paper is to predict that the new collective excited states may exist system-atically in odd-mass nuclei. Other purpose is to discuss a new collective band structure on the top of a unique-parity one-quasiparticle state. Through the numerical calculations, it has been clarified that the dynamical mutual interplay between the pairing and the quadrupole degrees of freedom played an important role in the odd-mass transitional nuclei to bring about the new type of collective states. The results of calculation were compared with the experimental data. (Kato, T.)

Multiphase patterns in periodically forced oscillatory systems

International Nuclear Information System (INIS)

Elphick, C.; Hagberg, A.; Meron, E.

1999-01-01

Periodic forcing of an oscillatory system produces frequency locking bands within which the system frequency is rationally related to the forcing frequency. We study extended oscillatory systems that respond to uniform periodic forcing at one quarter of the forcing frequency (the 4:1 resonance). These systems possess four coexisting stable states, corresponding to uniform oscillations with successive phase shifts of π/2. Using an amplitude equation approach near a Hopf bifurcation to uniform oscillations, we study front solutions connecting different phase states. These solutions divide into two groups: π fronts separating states with a phase shift of π and π/2 fronts separating states with a phase shift of π/2. We find a type of front instability where a stationary π front 'decomposes' into a pair of traveling π/2 fronts as the forcing strength is decreased. The instability is degenerate for an amplitude equation with cubic nonlinearities. At the instability point a continuous family of pair solutions exists, consisting of π/2 fronts separated by distances ranging from zero to infinity. Quintic nonlinearities lift the degeneracy at the instability point but do not change the basic nature of the instability. We conjecture the existence of similar instabilities in higher 2n:1 resonances (n=3,4,hor-ellipsis) where stationary π fronts decompose into n traveling π/n fronts. The instabilities designate transitions from stationary two-phase patterns to traveling 2n-phase patterns. As an example, we demonstrate with a numerical solution the collapse of a four-phase spiral wave into a stationary two-phase pattern as the forcing strength within the 4:1 resonance is increased. copyright 1999 The American Physical Society

BPM Offset Determination by Sinusoidal Quadrupole K-modulation

CERN Document Server

Baer, T; Wenninger, J

2011-01-01

To ensure an adequate orbit steering that maximizes the machine aperture, a good knowledge of the BPM measurement offsets is crucial. During this MD, a sinusoidal k-modulation of individually powered quadrupoles was performed to determine the offsets of the nearby BPMs. An accuracy of 10µm for the determination of the absolute beam position is reached.

Determination of nuclear quadrupole moments – An example of the synergy of ab initio calculations and microwave spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kellö, Vladimir [Department of Physical Chemistry, Comenius University, SK-842 15 Bratislava (Slovakia)

2015-01-22

Highly correlated scalar relativistic calculations of electric field gradients at nuclei in diatomic molecules in combination with accurate nuclear quadrupole coupling constants obtained from microwave spectroscopy are used for determination of nuclear quadrupole moments.

Oscillatory electroosmotic flow in a parallel-plate microchannel under asymmetric zeta potentials

Science.gov (United States)

Peralta, M.; Arcos, J.; Méndez, F.; Bautista, O.

2017-06-01

In this work, we conduct a theoretical analysis of the start-up of an oscillatory electroosmotic flow (EOF) in a parallel-plate microchannel under asymmetric zeta potentials. It is found that the transient evolution of the flow field is controlled by the parameters {R}ω , {R}\\zeta , and \\bar{κ }, which represent the dimensionless frequency, the ratio of the zeta potentials of the microchannel walls, and the electrokinetic parameter, which is defined as the ratio of the microchannel height to the Debye length. The analysis is performed for both low and high zeta potentials; in the former case, an analytical solution is derived, whereas in the latter, a numerical solution is obtained. These solutions provide the fundamental characteristics of the oscillatory EOFs for which, with suitable adjustment of the zeta potential and the dimensionless frequency, the velocity profiles of the fluid flow exhibit symmetric or asymmetric shapes.

Oscillatory blood pressure response to the onset of cycling exercise in men

DEFF Research Database (Denmark)

Barbosa, Thales C; Fernandes, Igor A; Magalhães-Jr, Nisval

2015-01-01

to this pattern is unclear. What is the main finding and its importance? We demonstrate that attenuation of group III/IV muscle afferent feedback by spinal fentanyl impairs the pressor response after 10 s of moderate leg cycling exercise, but this afferent feedback does not appear to be necessary for induction...... of the oscillatory pattern of blood pressure at the onset of exercise. We investigated whether attenuation of the central projections of group III/IV skeletal muscle afferents via lumbar intrathecal administration of the μ-opioid receptor agonist fentanyl affects the oscillatory blood pressure (BP) response...... to the onset of dynamic exercise. Eight healthy, recreationally active men (28 ± 3 years old) performed 40 s of cycling at 80 W (60 r.p.m.) before (control) and after fentanyl administration, while heart rate, stroke volume, cardiac output, systolic, mean and diastolic BP and total vascular conductance were...

Unzip instabilities: Straight to oscillatory transitions in the cutting of thin polymer sheets

Science.gov (United States)

Reis, P. M.; Kumar, A.; Shattuck, M. D.; Roman, B.

2008-06-01

We report an experimental investigation of the cutting of a thin brittle polymer sheet with a blunt tool. It was recently shown that the fracture path becomes oscillatory when the tool is much wider than the sheet thickness. Here we uncover two novel transitions from straight to oscillatory fracture by varying either the tilt angle of the tool or the speed of cutting, respectively. We denote these by angle and speed unzip instabilities and analyze them by quantifying both the dynamics of the crack tip and the final shapes of the fracture paths. Moreover, for the speed unzip instability, the straight crack lip obtained at low speeds exhibits out-of-plane buckling undulations (as opposed to being flat above the instability threshold) suggesting a transition from ductile to brittle fracture.

Nonlinear response of dense colloidal suspensions under oscillatory shear: mode-coupling theory and Fourier transform rheology experiments.

Science.gov (United States)

Brader, J M; Siebenbürger, M; Ballauff, M; Reinheimer, K; Wilhelm, M; Frey, S J; Weysser, F; Fuchs, M

2010-12-01

Using a combination of theory, experiment, and simulation we investigate the nonlinear response of dense colloidal suspensions to large amplitude oscillatory shear flow. The time-dependent stress response is calculated using a recently developed schematic mode-coupling-type theory describing colloidal suspensions under externally applied flow. For finite strain amplitudes the theory generates a nonlinear response, characterized by significant higher harmonic contributions. An important feature of the theory is the prediction of an ideal glass transition at sufficiently strong coupling, which is accompanied by the discontinuous appearance of a dynamic yield stress. For the oscillatory shear flow under consideration we find that the yield stress plays an important role in determining the nonlinearity of the time-dependent stress response. Our theoretical findings are strongly supported by both large amplitude oscillatory experiments (with Fourier transform rheology analysis) on suspensions of thermosensitive core-shell particles dispersed in water and Brownian dynamics simulations performed on a two-dimensional binary hard-disk mixture. In particular, theory predicts nontrivial values of the exponents governing the final decay of the storage and loss moduli as a function of strain amplitude which are in good agreement with both simulation and experiment. A consistent set of parameters in the presented schematic model achieves to jointly describe linear moduli, nonlinear flow curves, and large amplitude oscillatory spectroscopy.