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Sample records for dipole magnet cold

  1. Magnetic levitation for effective loading of cold cesium atoms in a crossed dipole trap

    Science.gov (United States)

    Li, Yuqing; Feng, Guosheng; Xu, Rundong; Wang, Xiaofeng; Wu, Jizhou; Chen, Gang; Dai, Xingcan; Ma, Jie; Xiao, Liantuan; Jia, Suotang

    2015-05-01

    We report a detailed study of effective magnetically levitated loading of cold atoms in a crossed dipole trap: an appropriate magnetic field gradient precisely compensates for the destructive gravitational force of the atoms and an additional bias field simultaneously eliminates the antitrapping potential induced by the magnetic field gradient. The magnetic levitation is required for a large-volume crossed dipole trap to form a shallow but very effective loading potential, making it a promising method for loading and trapping more cold atoms. For cold cesium atoms in the F =3 , m F =3 state prepared by three-dimensional degenerated Raman sideband cooling, a large number of atoms ˜3.2 ×106 have been loaded into a large-volume crossed dipole trap with the help of the magnetic levitation technique. The dependence of the number of atoms loaded and trapped in the dipole trap on the magnetic field gradient and bias field, respectively, is in good agreement with the theoretical analysis. The optimum magnetic field gradient of 31.13 G/cm matches the theoretical value of 31.3 G/cm well. This method can be used to obtain more cold atoms or a large number of Bose-Einstein condensation atoms for many atomic species in high-field seeking states.

  2. Twin Rotating Coils for Cold Magnetic Measurements of 15 m Long LHC Dipoles

    CERN Document Server

    Billan, J; Buzio, M; D'Angelo, G; Deferne, G; Dunkel, O; Legrand, P; Rijllart, A; Siemko, A; Sievers, P; Schloss, S; Walckiers, L

    2000-01-01

    We describe here a new harmonic coil system for the field measurement of the superconducting, twin aperture LHC dipoles and the associated corrector magnets. Besides field measurements the system can be used as an antenna to localize the quench origin. The main component is a 16 m long rotating shaft, made up of 13 ceramic segments, each carrying two tangential coils plus a central radial coil, all working in parallel. The segments are connected with flexible Ti-alloy bellows, allowing the piecewise straight shaft to follow the curvature of the dipole while maintaining high torsional rigidity. At each interconnection the structure is supported by rollers and ball bearings, necessary for the axial movement for installation and for the rotation of the coil during measurement. Two such shafts are simultaneously driven by a twin-rotating unit, thus measuring both apertures of a dipole at the same time. This arrangement allows very short measurement times (typically 10 s) and is essential to perform cold magnetic ...

  3. ‘The crab’ transporting LHC dipole cold mass

    CERN Multimedia

    Maximilien Brice

    2003-01-01

    For the careful transport of the LHC dipole magnets a robot, called ‘the crab’ has been specially built. It transports the cold masses between the storage area and assembly hall. These cold masses contain the cooling system and container for the dipole magnet.

  4. Proposal for the award of three contracts for the supply of the dipole magnet cold masses for the LHC

    CERN Document Server

    2001-01-01

    This document concerns the award of three contracts for the assembly, factory testing and delivery of cold masses of the dipole magnets for the LHC. Following a call for tenders (IT-2997/LHC/LHC), sent on 11 May 2001 to two firms and one consortium consisting of two firms, in three Member States, CERN received three tenders from the two firms and the consortium. The Finance Committee is invited to agree to the negotiation of contracts with the following consortium and two firms: (1) ALSTOM MAGNETS AND SUPERCONDUCTORS (FR) - JEUMONT INDUSTRIE (FR), for the supply of 386 cold masses for a total amount of 76 113 890 euros (118 128 738 Swiss francs), not subject to revision until 1 January 2003. The rate of exchange which has been used is that stipulated in the tender. (2) ANSALDO SUPERCONDUTTORI (IT), for the supply of 386 cold masses for a total amount of 76 354 394 euros (118 502 000 Swiss francs), not subject to revision until 1 January 2003. The rate of exchange which has been used is that stipulated in the ...

  5. A finite element model of the LHC dipole cold mass with hysteretic, non-linear behavior and single turn description: towards the interpretation of magnet quenches

    CERN Document Server

    AUTHOR|(CDS)2067087

    In one of its acceptation, the word quench is synonym of destruction. And this is even more consistent with reality in the case of the Large Hadron Collider dipole magnets, whose magnetic field and stored energy are unprecedented: the uncontrolled transition from the superconducting to the resistive state can be the origin of dramatic events. This is why the protection of magnets is so important, and why so many studies and investigations have been carried out on quench origin. The production, cold testing and installation of the 1232 arc dipole magnets is completed. They have fulfilled all the requirements and the operation reliability of these magnets has already been partially confirmed. From an academic standpoint, nevertheless, the anomalous mechanical behaviour, which was sometimes observed during power tests, has not yet been given a clear explanation. The work presented in this thesis aims at providing an instrument to better understand the reasons for such anomalies, by means of finite element modell...

  6. Giant Primeval Magnetic Dipoles

    Science.gov (United States)

    Thompson, Christopher

    2017-07-01

    Macroscopic magnetic dipoles are considered cosmic dark matter. Permanent magnetism in relativistic field structures can involve some form of superconductivity, one example being current-carrying string loops (“springs”) with vanishing net tension. We derive the cross-section for free classical dipoles to collide, finding it depends weakly on orientation when mutual precession is rapid. The collision rate of “spring” loops with tension { T }˜ {10}-8{c}4/G in galactic halos approaches the measured rate of fast radio bursts (FRBs) if the loops compose most of the dark matter. A large superconducting dipole (LSD) with mass ˜1020 g and size ˜1 mm will form a ˜100 km magnetosphere moving through interstellar plasma. Although hydromagnetic drag is generally weak, it is strong enough to capture some LSDs into long-lived rings orbiting supermassive black holes (SMBHs) that form by the direct collapse of massive gas clouds. Repeated collisions near young SMBHs could dominate the global collision rate, thereby broadening the dipole mass spectrum. Colliding LSDs produce tiny, hot electromagnetic explosions. The accompanying paper shows that these explosions couple effectively to propagating low-frequency electromagnetic modes, with output peaking at 0.01-1 THz. We describe several constraints on, and predictions of, LSDs as cosmic dark matter. The shock formed by an infalling LSD triggers self-sustained thermonuclear burning in a C/O (ONeMg) white dwarf (WD) of mass ≳1 M ⊙ (1.3 M ⊙). The spark is generally located off the center of the WD. The rate of LSD-induced explosions matches the observed rate of Type Ia supernovae.

  7. Magnetic monopoles and dipoles

    CERN Multimedia

    Dominguez, Daniel

    2016-01-01

    Conventional bar magnets are also called ‘magnetic dipoles’ because they have two magnetic poles (a “North” and a “South” magnetic pole, like the Earth). In theory, “magnetic monopoles” could exist that act like an isolated “magnetic charge”, i.e. either a “North” or a “South” magnetic pole.

  8. Magnetic dipole moment of a moving electric dipole

    OpenAIRE

    Hnizdo, V.

    2012-01-01

    The current density of a moving electric dipole is expressed as the sum of polarization and magnetization currents. The magnetic field due to the latter current is that of a magnetic dipole moment that is consistent with the relativistic transformations of the polarization and magnetization of macroscopic electrodynamics.

  9. Stacks of SPS Dipole Magnets

    CERN Multimedia

    1974-01-01

    Stacks of SPS Dipole Magnets ready for installation in the tunnel. The SPS uses a separated function lattice with dipoles for bending and quadrupoles for focusing. The 6.2 m long normal conducting dipoles are of H-type with coils that are bent-up at the ends. There are two types, B1 (total of 360) and B2 (384). Both are for a maximum field of 1.8 Tesla and have the same outer dimensions (450x800 mm2 vxh) but with different gaps (B1: 39x129 mm2, B2: 52x92 mm2) tailored to the beam size. The yoke, made of 1.5 mm thick laminations, consists of an upper and a lower half joined together in the median plane once the coils have been inserted.

  10. Dipole-Dipole Interactions of Charged Magnetic Grains

    CERN Document Server

    Perry, Jonathan; Hyde, Truell

    2010-01-01

    The interaction between dust grains is an important process in fields as diverse as planetesimal formation or the plasma processing of silicon wafers into computer chips. This interaction depends in large part on the material properties of the grains, for example whether the grains are conducting, non-conducting, ferrous or non-ferrous. This work considers the effects that electrostatic and magnetic forces, alone or in combination, can have on the coagulation of dust in various environments. A numerical model is used to simulate the coagulation of charged, charged-magnetic and magnetic dust aggregates formed from ferrous material and the results are compared to each other as well as to those from uncharged, non-magnetic material. The interactions between extended dust aggregates are also examined, specifically looking at how the arrangement of charge over the aggregate surface or the inclusion of magnetic material produces dipole-dipole interactions. It will be shown that these dipole-dipole interactions can ...

  11. Magnetic Field of a Dipole and the Dipole-Dipole Interaction

    Science.gov (United States)

    Kraftmakher, Yaakov

    2007-01-01

    With a data-acquisition system and sensors commercially available, it is easy to determine magnetic fields produced by permanent magnets and to study the dipole-dipole interaction for different separations and angular positions of the magnets. For sufficiently large distances, the results confirm the 1/R[superscript 3] law for the magnetic field…

  12. Magnetic dipole oscillations and radiation damping

    Science.gov (United States)

    Stump, Daniel R.; Pollack, Gerald L.

    1997-01-01

    We consider the problem of radiation damping for a magnetic dipole oscillating in a magnetic field. An equation for the radiation reaction torque is derived, and the damping of the oscillations is described. Also discussed are runaway solutions for a rotating magnetic dipole moving under the influence of the reaction torque, with no external torque.

  13. Population Dynamics in Cold Gases Resulting from the Long-Range Dipole-Dipole Interaction

    CERN Document Server

    Mandilara, A; Pillet, P

    2009-01-01

    We consider the effect of the long range dipole-dipole interaction on the excitation exchange dynamics of cold two-level atomic gase in the conditions where the size of the atomic cloud is large as compared to the wavelength of the dipole transition. We show that this interaction results in population redistribution across the atomic cloud and in specific spectra of the spontaneous photons emitted at different angles with respect to the direction of atomic polarization.

  14. Gravitational radiation from a rotating magnetic dipole

    CERN Document Server

    Hacyan, Shahen

    2016-01-01

    The gravitational radiation emitted by a rotating magnetic dipole is calculated. Formulas for the polarization amplitudes and the radiated power are obtained in closed forms, considering both the near and radiation zones of the dipole. For a neutron star, a comparison is made with other sources of gravitational and electromagnetic radiation.

  15. How to Introduce the Magnetic Dipole Moment

    Science.gov (United States)

    Bezerra, M.; Kort-Kamp, W. J. M.; Cougo-Pinto, M. V.; Farina, C.

    2012-01-01

    We show how the concept of the magnetic dipole moment can be introduced in the same way as the concept of the electric dipole moment in introductory courses on electromagnetism. Considering a localized steady current distribution, we make a Taylor expansion directly in the Biot-Savart law to obtain, explicitly, the dominant contribution of the…

  16. Dipole blockade in a cold Rydberg atomic sample

    CERN Document Server

    Comparat, Daniel; 10.1364/JOSAB.27.00A208

    2010-01-01

    We review here the studies performed about interactions in an assembly of cold Rydberg atoms. We focus more specially the review on the dipole-dipole interactions and on the effect of the dipole blockade in the laser Rydberg excitation, which offers attractive possibilities for quantum engineering. We present first the various interactions between Rydberg atoms. The laser Rydberg excitation of such an assembly is then described with the introduction of the dipole blockade phenomenon. We report recent experiments performed in this subject by starting with the case of a pair of atoms allowing the entanglement of the wave-functions of the atoms and opening a fascinating way for the realization of quantum bits and quantum gates. We consider then several works on the blockade effect in a large assembly of atoms for three different configurations: blockade through electric-field induced dipole, through F\\"orster resonance and in van der Waals interaction. The properties of coherence and cooperativity are analyzed. ...

  17. Interaction between two magnetic dipoles in a uniform magnetic field

    Directory of Open Access Journals (Sweden)

    J. G. Ku

    2016-02-01

    Full Text Available A new formula for the interaction force between two magnetic dipoles in a uniform magnetic field is derived taking their mutual magnetic interaction into consideration and used to simulate their relative motion. Results show that when the angle β between the direction of external magnetic field and the centerline of two magnetic dipoles is 0 ° or 90 °, magnetic dipoles approach each other or move away from each other in a straight line, respectively. And the time required for them to contact each other from the initial position is related to the specific susceptibility and the diameter of magnetic particles, medium viscosity and magnetic field strength. When β is between 0 ° and 90 °, magnetic dipole pair performs approximate elliptical motion, and the motion trajectory is affected by the specific susceptibility, diameter and medium viscosity but not magnetic field strength. However, time required for magnetic dipoles to complete the same motion trajectory is shorter when adopting stronger magnetic field. Moreover, the subsequent motion trajectory of magnetic dipoles is ascertained once the initial position is set in a predetermined motion trajectory. Additionally, magnetic potential energy of magnetic dipole pairs is transformed into kinetic energy and friction energy during the motion.

  18. Installation of the ALICE dipole magnet

    CERN Multimedia

    Maximilien Brice

    2005-01-01

    The large dipole magnet is installed on the ALICE detector at CERN. This magnet, which is cooled by demineralised water, will bend the path of muons that leave the huge rectangular solenoid (in the background). These muons are heavy electrons that interact less with matter, allowing them to traverse the main section of the detector.

  19. Test Results for LHC Insertion Region Dipole Magnets

    CERN Document Server

    Muratore, Joseph F; Cozzolino, John P; Ganetis, George; Ghosh, Arup; Gupta, Ramesh C; Harrison, Michael; Kumar-Jain, Animesh; Marone, Andrew; Richard-Plate, Stephen; Schmalzle, Jesse D; Thomas, Richard A; Wanderer, Peter; Willen, Erich; Wu, Kuo-Chen

    2005-01-01

    The Superconducting Magnet Division at Brookhaven National Laboratory (BNL) has made 20 insertion region dipoles for the Large Hadron Collider (LHC) at CERN. These 9.45 m-long, 8 cm aperture magnets have the same coil design as the arc dipoles now operating in the Relativistic Heavy Ion Collider (RHIC) at BNL and are of single aperture, twin aperture, and double cold mass configurations. They produce fields up to 3.8 T for operation at 7.56 TeV. Eighteen of these magnets have been tested at 4.5 K using either forced flow supercritical helium or liquid helium. The testing was especially important for the twin aperture models, which have the most challenging design. In these, the dipole fields in both apertures point in the same direction, unlike LHC arc dipoles. This paper reports on the results of these tests, including spontaneous quench performance, verification of quench protection heater operation, and magnetic field quality. Magnetic field measurements were done at 4.5K and at room temperature, and warm-...

  20. Modeling and analysis of magnetic dipoles in weak magnetic field

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The magnetic leakage field distribution resulting from linear defects of a tube sample in the geomagnetic field is modeled according to the magnetic dipole theory.The formula to compute the normal component of the weak magnetic field is deduced based on the spatial distribution of the magnetic dipole.The shape and characteristics of the zero line (an important criterion for magnetic memory testing) of the normal field is analyzed under different longitudinal magnetizations.Results show that the characteristics of the zero line should be considered when the metal magnetic memory testing method is used to find and locate the defect.

  1. Near-Field Magnetic Dipole Moment Analysis

    Science.gov (United States)

    Harris, Patrick K.

    2003-01-01

    This paper describes the data analysis technique used for magnetic testing at the NASA Goddard Space Flight Center (GSFC). Excellent results have been obtained using this technique to convert a spacecraft s measured magnetic field data into its respective magnetic dipole moment model. The model is most accurate with the earth s geomagnetic field cancelled in a spherical region bounded by the measurement magnetometers with a minimum radius large enough to enclose the magnetic source. Considerably enhanced spacecraft magnetic testing is offered by using this technique in conjunction with a computer-controlled magnetic field measurement system. Such a system, with real-time magnetic field display capabilities, has been incorporated into other existing magnetic measurement facilities and is also used at remote locations where transport to a magnetics test facility is impractical.

  2. The SPS tunnel with a dipole magnet

    CERN Multimedia

    1976-01-01

    The SPS uses about 800 6-m long dipole magnets to bend the beam around its path. Particle beams come into the SPS from the smaller PS accelerator at 26 GeV. The SPS then accelerates the beam further up to 450 GeV when the beam is extracted and transferred to the LHC or CERN Neutrinos to Gran Sasso (CNGS).

  3. The radiofrequency magnetic dipole discharge

    Science.gov (United States)

    Martines, E.; Zuin, M.; Marcante, M.; Cavazzana, R.; Fassina, A.; Spolaore, M.

    2016-05-01

    This paper describes a novel and simple concept of plasma source, which is able to produce a radiofrequency magnetized discharge with minimal power requirements. The source is based on the magnetron concept and uses a permanent magnet as an active electrode. The dipolar field produced by the magnet confines the electrons, which cause further ionization, thus producing a toroidally shaped plasma in the equatorial region around the electrode. A plasma can be ignited with such scheme with power levels as low as 5 W. Paschen curves have been built for four different working gases, showing that in Helium or Neon, plasma breakdown is easily obtained also at atmospheric pressure. The plasma properties have been measured using a balanced Langmuir probe, showing that the electron temperature is around 3-4 eV and higher in the cathode proximity. Plasma densities of the order of 1016 m-3 have been obtained, with a good positive scaling with applied power. Overall, the electron pressure appears to be strongly correlated with the magnetic field magnitude in the measurement point.

  4. Prototype steel-concrete LEP dipole magnet

    CERN Multimedia

    1981-01-01

    The magnetic field needed in the LEP dipole magnets was rather low, of a fraction of tesla. This lead to the conception of a novel yoke structure consisting of stacks of 1.5 mm thick low-carbon steel laminations spaced by 4.1 mm with the spaces filled with concrete. The excitation coils were also very simple: aluminium bars insulated by polyester boxes in this prototype, by glass-epoxy in the final magnets. For details see LEP-Note 118,1978 and LEP-Note 233 1980. See also 8111529,7908528X.

  5. Numerical simulations of magnetic suspensions with hydrodynamic and dipole-dipole magnetic interactions

    Science.gov (United States)

    Gontijo, R. G.; Cunha, F. R.

    2017-06-01

    This work describes a numerical model to compute the translational and rotational motion of N spherical magnetic particles settling in a quiescent viscous fluid under creeping flow condition. The motion of the particles may be produced by the action of gravitational forces, Brownian thermal fluctuations, magnetic dipole-dipole interactions, external magnetic field, and hydrodynamic interactions. In order to avoid particle overlap, we consider a repulsive force based on a variation of a screened-Coulomb potential mixed with Hertz contact forces. The inertia of the particles is neglected so that a mobility approach to describe the hydrodynamic interactions is used. The magnetic dipoles are fixed with respect to the particles themselves. Thus they can only interact magnetically between them and with an external applied magnetic field. Therefore the effect of magnetic field moment rotation relative to the particle as a consequence of a finite amount of particle anisotropy is neglected in this work. On the other hand, the inclusion of particle viscous hydrodynamic interactions and dipolar interactions is considered in our model. Both long-range hydrodynamic and magnetic interactions are accounted by a sophisticated technique of lattice sums. This work considers several possibilities of periodic and non-periodic particle interaction schemes. This paper intends to show the benefits and disadvantages of the different approaches, including a hybrid possibility of computing periodic and non-periodic particle interactions. The well-known mean sedimentation velocity and the equilibrium magnetization of the suspension are computed to validate the numerical scheme. The comparison is performed with the existent theoretical models valid for dilute suspensions and several empirical correlations available in the current literature. In the presence of dipole-dipole particle interactions, the simulations show a non-monotonic behavior of the mean sedimentation velocity as the particle

  6. Electrically Small Magnetic Dipole Antennas with Magnetic Core

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Breinbjerg, Olav

    2010-01-01

    This work extends the theory of a spherical magnetic dipole antenna with magnetic core by numerical results for practical antenna configurations that excite higher-order modes besides the main TE10 spherical mode. The multiarm spherical helix (MSH) and the spherical split ring (SSR) antennas...

  7. Magnetic Dipole Band in 113^In

    Institute of Scientific and Technical Information of China (English)

    马克岩; 杨东; 陆景彬; 王烈林; 王辉东; 刘运祚; 刘弓冶; 李黎; 马英君; 杨森; 李广生; 贺创业; 李雪琴

    2012-01-01

    High spin states in the odd-A nucleus 113^In have been investigated using the re- action 110^Pd(7^Li, 4n) at a beam energy of 50 MeV. A new positive parity dipole band with the configuration of π(g9/2)^-lv(h11/2)^2 v (g7/2)^2 is established. The effective interaction V(θ) values of this band have been successfully described by a semiclassical geometric model based on shear mechanism, which show that the dipole band has the characteristics of magnetic rotation. In addition the collective rotational angular momentum for this band is extracted. The results show that the core contribution increases gradually with the increase of the rotation frequency.

  8. Role of dipole-dipole interaction on the magnetic dynamics of anisotropic layered cuprate antiferromagnets

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, M. [Dept. of Physics and Astro-Physics, Univ. of Delhi (India); Govind, N.; Pratap, A. [Condense Matter Theory Group, National Physical Lab., New Delhi (India); Ajay; Tripathi, R.S. [Dept. of Physics, G.B. Pant Univ. of Agriculture and Technology, Pantnagar (India)

    2001-07-01

    In the present paper, we report the role of dipole-dipole interaction on the magnetic dynamics of single layer antiferromagnets. For this, the model Hamiltonian includes the exchange Heisenberg Hamiltonian as well as dipole-dipole interactions. Within the linear spin-wave theory, we employ the double time Green's function technique to obtain expressions for the spin wave dispersion, sublattice magnetization and the magnetic contribution to specific heat as a function of various parameters of the model Hamiltonian. We observe through numerical calculations that in the absence of anisotropy in exchange couplings the dipole-dipole interaction works as an anisotropy and sustains the magnetization even in a pure 2D system. (orig.)

  9. Moles, Laser, Mirrors and the Measurement of LHC Dipole Cold Masses

    CERN Multimedia

    2002-01-01

    Marta Bajko measuring the geometry of a dipole magnet with the 3-D laser measuring machine. Over in buildings 181 and SM 18 the LHC dipole magnets await final measurements to make sure they are of exactly the right geometry (shape). And since the dipole cold masses are not straight (they are slightly bent in the horizontal plane), getting them to meet their very tight assembly tolerances of tenth of millimetre is not an easy task. 'We are aiming for one order of magnitude better than that which we actually need for the accuracy of the measurements, and old school rulers of any sort cannot handle these requirements,' says Marta Bajko, one of the project's engineers, 'for our work we need to rely on optical measuring technology.' And rely on optical measuring is exactly what they have done. The dipole measurements are being taken with a gadget called LTD 500 (Laser Tracker and Absolute Distance-Meter), created by Leica Geosystems, a Swiss Company that designs and distributes high precision measurement technol...

  10. Magnetic dipole states in /sup 206/Pb

    Energy Technology Data Exchange (ETDEWEB)

    Ponomarev, V.; Vdovin, A.; Velchev, Ch.

    1987-12-01

    The fragmentation of the magnetic dipole strength in /sup 206/Pb is studied in the framework of the quasiparticle-phonon nuclear model. The calculations reproduce the two-humped shape of the experimental distribution. As in /sup 208/Pb there is an isoscalar 1/sup +/ state at Esub(x) approx. = 5.7 MeV in /sup 206/Pb and its wavefunction contains sizable two-photon components. It is shown that direct transitions from the ground state to two-phonon 1/sup +/ states give a negligible contribution to the total excitation probability of the M1 resonance.

  11. Cable Magnetization Effects in the LHC Main Dipole Magnets

    CERN Document Server

    Bottura, L; Walckiers, L; Wolf, R

    1998-01-01

    Several short (1 m) and long (10 m) dipole models have been tested within the scope of the on-going R&D programme for LHC at CERN. We report here the results of measurements of field quality in these dipoles, focussing on the contribution of cable magnetization. We show that the results obtained over a significant (> 10) number of magnets at 1.8 and 4.2 K are in reasonable agreement with calculati ons of the dependence of allowed harmonics on field. The calculations are based on the Bean model of filament magnetization and assume an approximate Jc(B) dependence, calibrated against low field mea surements of strand magnetization. The field quality measurements at low field also correlate satisfactorily to measurements of cable critical current at high field and geometric filament diameter.

  12. Synchronization of magnetic dipole rotation in an ac magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Belovs, M; Cebers, A, E-mail: aceb@tesla.sal.lv [University of Latvia, Zellu-8, Riga, LV-1002 (Latvia)

    2011-07-22

    The synchronization of the rotation of magnetic dipoles due to weak dipolar interactions is studied. The set of equations is analyzed by the time averaging technique. It is found that dipoles synchronously oscillate at low applied fields and rotate synchronously at large applied fields. The mean angular velocity of synchronous rotation increases with the field strength and reaches a constant value equal to the angular frequency of the field above the critical value of the field strength. The critical value of the field strength above which the synchronous rotation takes place can be calculated from dimensionless parameters using a model derived from first principles by others. The values thus obtained are in good agreement with the values we obtain from a numerical simulation. Thus, we may conclude that the liquid flow observed in these systems may be caused by synchronized rotations of the dipoles.

  13. Magnetic Dipoles and Quantum Coherence in Muscle Contraction

    CERN Document Server

    Hatori, K; Matsuno, K; Hatori, Kuniyuki; Honda, Hajime; Matsuno, Koichiro

    2001-01-01

    An actin filament contacting myosin molecules as a functional unit of muscle contraction induces magnetic dipoles along the filament when ATP molecules to be hydrolyzed are available there. The induced magnetic dipoles are coherent over the entire filament, though they are fluctuating altogether as constantly being subject to the ambient thermal agitations.

  14. Acceleration of magnetic dipoles by the sequence of current turns

    CERN Document Server

    Dolya, S N

    2014-01-01

    Acceleration of magnetic dipoles is carried out by the running gradient of the magnetic field formed while sequent switching on the current turns. Magnetic dipoles, with a diameter of sixty millimeters and full length one meter, are pre-accelerated by using the gas-dynamic method to speed one kilometer per second, corresponding to the injection rate into the main accelerator. To prevent the turning of the dipoles by one hundred eighty degrees in the field of the accelerating pulse and focus them, the magnetic dipoles are accelerated inside the titanium tube. The magnetic dipoles have mass two kilograms and acquire the finite speed five kilometers per second on the acceleration length three hundreds meters.

  15. Strongly magnetized rotating dipole in general relativity

    Science.gov (United States)

    Pétri, J.

    2016-10-01

    Context. Electromagnetic waves arise in many areas of physics. Solutions are difficult to find in the general case. Aims: We numerically integrate Maxwell equations in a 3D spherical polar coordinate system. Methods: Straightforward finite difference methods would lead to a coordinate singularity along the polar axis. Spectral methods are better suited for such artificial singularities that are related to the choice of a coordinate system. When the radiating object rotates like a star, for example, special classes of solutions to Maxwell equations are worthwhile to study, such as quasi-stationary regimes. Moreover, in high-energy astrophysics, strong gravitational and magnetic fields are present especially around rotating neutron stars. Results: To study such systems, we designed an algorithm to solve the time-dependent Maxwell equations in spherical polar coordinates including general relativity and quantum electrodynamical corrections to leading order. As a diagnostic, we computed the spin-down luminosity expected for these stars and compared it to the classical or non-relativistic and non-quantum mechanical results. Conclusions: Quantum electrodynamics leads to an irrelevant change in the spin-down luminosity even for a magnetic field of about the critical value of 4.4 × 109 T. Therefore the braking index remains close to its value for a point dipole in vacuum, namely n = 3. The same conclusion holds for a general-relativistic quantum electrodynamically corrected force-free magnetosphere.

  16. Cryogenic magnetic coil and superconducting magnetic shield for neutron electric dipole moment searches

    Science.gov (United States)

    Slutsky, S.; Swank, C. M.; Biswas, A.; Carr, R.; Escribano, J.; Filippone, B. W.; Griffith, W. C.; Mendenhall, M.; Nouri, N.; Osthelder, C.; Pérez Galván, A.; Picker, R.; Plaster, B.

    2017-08-01

    A magnetic coil operated at cryogenic temperatures is used to produce spatial, relative field gradients below 6 ppm/cm, stable for several hours. The apparatus is a prototype of the magnetic components for a neutron electric dipole moment (nEDM) search, which will take place at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory using ultra-cold neutrons (UCN). That search requires a uniform magnetic field to mitigate systematic effects and obtain long polarization lifetimes for neutron spin precession measurements. This paper details upgrades to a previously described apparatus [1], particularly the introduction of super-conducting magnetic shielding and the associated cryogenic apparatus. The magnetic gradients observed are sufficiently low for the nEDM search at SNS.

  17. Improved Reconstruction of Dipole Directions from Spherical Magnetic Field Measurements

    CERN Document Server

    Gerhards, Christian

    2016-01-01

    Reconstructing magnetizations from measurements of the generated magnetic potential is highly non-unique. The matter of uniqueness can be improved, but not entirely resolved, by the assumption that the magnetization is locally supported. Here, we focus on the case that the magnetization is additionally assumed to be induced by an ambient magnetic dipole field, i.e., the task is to reconstruct the dipole direction as well as the susceptibility of the magnetic material. We investigate uniqueness issues and provide a reconstruction procedure from given magnetic potential measurements on a spherical surface.

  18. Magnetic field homogeneity perturbations in finite Halbach dipole magnets.

    Science.gov (United States)

    Turek, Krzysztof; Liszkowski, Piotr

    2014-01-01

    Halbach hollow cylinder dipole magnets of a low or relatively low aspect ratio attract considerable attention due to their applications, among others, in compact NMR and MRI systems for investigating small objects. However, a complete mathematical framework for the analysis of magnetic fields in these magnets has been developed only for their infinitely long precursors. In such a case the analysis is reduced to two-dimensions (2D). The paper details the analysis of the 3D magnetic field in the Halbach dipole cylinders of a finite length. The analysis is based on three equations in which the components of the magnetic flux density Bx, By and Bz are expanded to infinite power series of the radial coordinate r. The zeroth term in the series corresponds to a homogeneous magnetic field Bc, which is perturbed by the higher order terms due to a finite magnet length. This set of equations is supplemented with an equation for the field profile B(z) along the magnet axis, presented for the first time. It is demonstrated that the geometrical factors in the coefficients of particular powers of r, defined by intricate integrals are the coefficients of the Taylor expansion of the homogeneity profile (B(z)-Bc)/Bc. As a consequence, the components of B can be easily calculated with an arbitrary accuracy. In order to describe perturbations of the field due to segmentation, two additional equations are borrowed from the 2D theory. It is shown that the 2D approach to the perturbations generated by the segmentation can be applied to the 3D Halbach structures unless r is not too close to the inner radius of the cylinder ri. The mathematical framework presented in the paper was verified with great precision by computations of B by a highly accurate integration of the magnetostatic Coulomb law and utilized to analyze the inhomogeneity of the magnetic field in the magnet with the accuracy better than 1 ppm.

  19. Lunar magnetic field - Permanent and induced dipole moments

    Science.gov (United States)

    Russell, C. T.; Coleman, P. J., Jr.; Schubert, G.

    1974-01-01

    Apollo 15 subsatellite magnetic field observations have been used to measure both the permanent and the induced lunar dipole moments. Although only an upper limit of 1.3 x 10 to the 18th gauss-cubic centimeters has been determined for the permanent dipole moment in the orbital plane, there is a significant induced dipole moment which opposes the applied field, indicating the existence of a weak lunar ionosphere.

  20. Spread in Dipole Cable Magnetization and Consequences on the Spread of DC Persistent Currents in the Main Dipole of the Large Hadron Collider

    CERN Document Server

    Bellesia, B; Granata, V; Le Naour, S; Oberli, L R; Sanfilippo, S; Santoni, C; Scandale, Walter; Schwerg, N; Todesco, Ezio; Völlinger, C

    2004-01-01

    The production of more than 60% of superconducting cables for the main dipoles of the Large Hadron Collider has been completed. The results of the measurements of cable magnetization and the dependence on the manufacturer are presented. The strand magnetization produces field errors that have been measured in a large number of dipoles, all tested in cold conditions. We examine here the correlation between the available magnetic measurements and the large database of cable magnetization. The analysis is based on models documented in the literature. Finally, a forecast of the persistent current effects to be expected in the LHC main dipoles is presented, and the more critical parameters for beam dynamics are singled out.

  1. Cold denaturation induces inversion of dipole and spin transfer in chiral peptide monolayers

    Science.gov (United States)

    Eckshtain-Levi, Meital; Capua, Eyal; Refaely-Abramson, Sivan; Sarkar, Soumyajit; Gavrilov, Yulian; Mathew, Shinto P.; Paltiel, Yossi; Levy, Yaakov; Kronik, Leeor; Naaman, Ron

    2016-02-01

    Chirality-induced spin selectivity is a recently-discovered effect, which results in spin selectivity for electrons transmitted through chiral peptide monolayers. Here, we use this spin selectivity to probe the organization of self-assembled α-helix peptide monolayers and examine the relation between structural and spin transfer phenomena. We show that the α-helix structure of oligopeptides based on alanine and aminoisobutyric acid is transformed to a more linear one upon cooling. This process is similar to the known cold denaturation in peptides, but here the self-assembled monolayer plays the role of the solvent. The structural change results in a flip in the direction of the electrical dipole moment of the adsorbed molecules. The dipole flip is accompanied by a concomitant change in the spin that is preferred in electron transfer through the molecules, observed via a new solid-state hybrid organic-inorganic device that is based on the Hall effect, but operates with no external magnetic field or magnetic material.

  2. Magnetic dipole moment and keV neutrino dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Chao-Qiang, E-mail: geng@phys.nthu.edu.tw [Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan (China); Physics Division, National Center for Theoretical Sciences, Hsinchu 300, Taiwan (China); Takahashi, Ryo, E-mail: ryo.takahasi88@gmail.com [Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan (China)

    2012-04-04

    We study magnetic dipole moments of right-handed neutrinos in a keV neutrino dark matter model. This model is a simple extension of the standard model with only right-handed neutrinos and a pair of charged particles added. One of the right-handed neutrinos is the candidate of dark matter with a keV mass. Some bounds on the dark matter magnetic dipole moment and model parameters are obtained from cosmological observations.

  3. Magnetic dipole moment and keV neutrino dark matter

    CERN Document Server

    Geng, Chao-Qiang

    2012-01-01

    We study magnetic dipole moments of right-handed neutrinos in a keV neutrino dark matter model. This model is a simple extension of the standard model with only right-handed neutrinos and a pair of charged particles added. One of the right-handed neutrinos is the candidate of dark matter with a keV mass. Some bounds on the dark matter magnetic dipole moment and model parameters are obtained from cosmological observations.

  4. Magnetic dipole moments of the heavy tensor mesons in QCD

    CERN Document Server

    Aliev, T M; Savcı, M

    2015-01-01

    The magnetic dipole moments of the ${\\cal D}_2$, and ${\\cal D}_{S_2}$, ${\\cal B}_2$, and ${\\cal B}_{S_2}$ heavy tensor mesons are estimated in framework of the light cone QCD sum rules. It is observed that the magnetic dipole moments for the charged mesons are larger than that of its neutral counterpart. It is found that the $SU(3)$ flavor symmetry violation is about 10\\% in both $b$ and $c$ sectors.

  5. Sedimentation equilibrium of magnetic nanoparticles with strong dipole-dipole interactions

    Science.gov (United States)

    Kuznetsov, Andrey A.; Pshenichnikov, Alexander F.

    2017-03-01

    Langevin dynamics simulation is used to study the suspension of interacting magnetic nanoparticles (dipolar spheres) in a zero applied magnetic field and in the presence of a gravitational (centrifugal) field. A particular emphasis is placed on the equilibrium vertical distribution of particles in the infinite horizontal slab. An increase in the dipolar coupling constant λ (the ratio of dipole-dipole interaction energy to thermal energy) from zero to seven units causes an increase in the particle segregation coefficient by several orders of magnitude. The effect of anisotropic dipole-dipole interactions on the concentration profile of particles is the same as that of the isotropic van der Waals attraction modeled by the Lennard-Jones potential. In both cases, the area with a high-density gradient separating the area with high and low particle concentration is formed on the profiles. Qualitative difference between two potentials manifests itself only in the fact that in the absence of a gravitational field the dipole-dipole interactions do not lead to the "gas-liquid" phase transition: no separation of the system into weakly and highly concentrated phases is observed. At high particle concentration and at large values of λ , the orientational ordering of magnetic dipoles takes place in the system. Magnetic structure of the system strongly depends on the imposed boundary conditions. Spontaneous magnetization occurs in the infinite horizontal slab (i.e., in the rectangular cell with two-dimensional periodic boundary conditions). Replacement of the infinite slab by the finite-size hard-wall vertical cylinder leads to the formation of azimuthal (vortex-like) order. The critical values of the coupling constant corresponding to the transition into an ordered state are very close for two geometries.

  6. Influence of geometrical parameters on the flexural rigidity of the LHC dipole cold mass assembly

    CERN Document Server

    Bajko, M; Pardons, A

    2002-01-01

    In order to predict the mechanical behavior of the LHC dipole cold mass in situations such as handling, transport and cool down, a number of important structural parameters are required. The dipole's flexural rigidity determines entirely the mechanical elastic behavior of the cold mass. Therefore, models of a bent cold mass were created to calculate its rigidity. This paper presents a simplified parametric finite element model, created to study the deflection of the cold mass in different situations and supporting conditions. The sensitivity of the models to the supporting conditions is computed. To provide the finite element and the analytical models with input, the deflection of the cold mass under discrete loads in normal condition and then 90-degrees rotated were measured with a laser tracker. By comparing models with measurements, the vertical and transversal rigidity of the cold mass assembly are determined. Additionally, the paper reports on the plastic behavior of the cold mass assembly in the range o...

  7. Performance of the Main Dipole Magnet Circuits of the LHC during Commissioning

    CERN Document Server

    Verweij, A; Ballarino, A; Bellesia, B; Bordry, Frederick; Cantone, A; Casas Lino, M; Castaneda Serra, A; Castillo Trello, C; Catalan-Lasheras, N; Charifoulline, Z; Coelingh, G; Dahlerup-Petersen, K; D'Angelo, G; Denz, R; Fehér, S; Flora, R; Gruwé, M; Kain, V; Khomenko, B; Kirby, G; MacPherson, A; Marqueta Barbero, A; Mess, K H; Modena, M; Mompo, R; Montabonnet, V; le Naour, S; Nisbet, D; Parma, V; Pojer, M; Ponce, L; Raimondo, A; Redaelli, S; Reymond, H; Richter, D; de Rijk, G; Rijllart, A; Romera Ramirez, I; Saban, R; Sanfilippo, S; Schmidt, R; Siemko, A; Solfaroli Camillocci, M; Thurel, Y; Thiessen, H; Venturini-Delsolaro, W; Vergara Fernandez, A; Wolf, R; Zerlauth, M

    2008-01-01

    During hardware commissioning of the Large Hadron Collider (LHC), 8 main dipole circuits are tested at 1.9 K and up to their nominal current. Each dipole circuit contains 154 magnets of 15 m length, and has a total stored energy of up to 1.3 GJ. All magnets are wound from Nb-Ti superconducting Rutherford cables, and contain heaters to quickly force the transition to the normal conducting state in case of a quench, and hence reduce the hot spot temperature. In this paper the performance of the first three of these circuits is presented, focussing on quench detection, heater performance, operation of the cold bypass diodes, and magnet-to-magnet quench propagation. The results as measured on the entire circuits will be compared to the test results obtained during the reception tests of the individual magnets.

  8. Electric and magnetic dipole couplings in split ring resonator metamaterials

    Institute of Scientific and Technical Information of China (English)

    Fan Jing; Sun Guang-Yong; and Zhu Wei-Ren

    2011-01-01

    In this paper,the electric and the magnetic dipole couplings between the outer and the inner rings of a single split ring resonator (SRR) are investigated.We numerically demonstrate that the magnetic resonance frequency can be substantially modified by changing the couplings of the electric and magnetic dipoles,and give a theoretical expression of the magnetic resonance frequency.The results in this work are expected to be conducive to a deeper understanding of the SRR and other similar metamaterials,and provide new guidance for complex metamaterials design with a tailored electromagnetic response.

  9. Instability of strong magnetic field and neutrino magnetic dipole moment

    CERN Document Server

    Lee, Hyun Kyu

    2016-01-01

    Vacuum instability of the strong electromagnetic field has been discussed since long time ago. The instability of the strong electric field due to creation of electron pairs is one of the examples, which is known as Schwinger process. What matters are the coupling of particles to the electromagnetic field and the mass of the particle to be produced. The critical electric field for electrons in the minimal coupling is ~ m^2/e . Spin 1/2 neutral particles but with magnetic dipole moments can interact with the electromagnetic field through Pauli coupling. The instability of the particular vacuum under the strong magnetic field can be formulated as the emergence of imaginary parts of the effective potential. In this talk, the development of the imaginary part in the effective potential as a function of the magnetic field strength is discussed for the configurations of the uniform magnetic field and the inhomogeneous magnetic field. Neutrinos are the lightest particle(if not photon or gluon) in the "standard model...

  10. Properties of the superconductor in accelerator dipole magnets

    Science.gov (United States)

    Teravest, Derk

    Several aspects of the application of superconductors to high field dipole magnets for particle accelerators are discussed. The attention is focused on the 10 tesla (1 m model) magnet that is envisaged for the future Large Hadron Collider (LHC) accelerator. The basic motivation behind the study is the intention of employing superconductors to their utmost performance. An overview of practical supercomputers, their applications and their impact on high field dipole magnets used for particle accelerators, is presented. The LHC reference design for the dipole magnets is outlined. Several models were used to study the influence of a number of factors in the shape and in particular, the deviation from the shape that is due to the flux flow state. For the investigated extrinsic and intrinsic factors, a classification can be made with respect to the effect on the shape of the characteristic of a multifilamentary wire. The optimization of the coil structure for high field dipole magnets, with respect to the field quality is described. An analytical model for solid and hollow filaments, to calculate the effect of filament magnetization in the quality of the dipole field, is presented.

  11. Magnetic fluids - suspensions of magnetic dipoles and their magnetic control

    CERN Document Server

    Odenbach, S

    2003-01-01

    Suspensions of magnetic nanoparticles exhibit normal liquid behaviour coupled with superparamagnetic properties. This leads to the possibility to control the properties and the flow of these liquids with moderate magnetic fields. The magnetic control enables various experiments in fluid mechanics and gives rise to the development of numerous technical and medical applications. Ferrofluids and their general properties will be introduced and, as examples for the magnetic control of their flow and properties, thermomagnetic convection and magnetoviscous effects will be discussed in some detail.

  12. Automated Design of a Correction Dipole Magnet for LHC

    CERN Document Server

    Karppinen, M; Ijspeert, Albert

    1996-01-01

    A correction dipole magnet, with a horizontal dipole nested inside a vertical dipole has been designed and optimized linking together different electromagnetic software and CAD/CAM systems. The necessary interfaces have recently been established in the program ROXIE which has been developed at CERN for the automatic generation and optimization of superconducting coil geometries. The program provides, in addition to a mathematical optimization chest, interfaces to commercial electromagnetic and structural software packages, CAD/CAM and databases. The results from electromagnetic calculations with different programs have been compared. Some modelling considerations to reduce the computation time are also given.

  13. Resonances and dipole moments in dielectric, magnetic, and magnetodielectric cylinders

    DEFF Research Database (Denmark)

    Dirksen, A.; Arslanagic, Samel; Breinbjerg, Olav

    2011-01-01

    An eigenfunction solution to the problem of plane wave scattering by dielectric, magnetic, and magnetodielectric cylinders is used for a systematic investigation of their resonances. An overview of the resonances with electric and magnetic dipole moments, needed in, e.g., the synthesis...... of metamaterials, is given with an emphasis on their strength, bandwidth, and isolation....

  14. Minimum Q Electrically Small Spherical Magnetic Dipole Antenna - Theory

    DEFF Research Database (Denmark)

    Breinbjerg, Olav; Kim, Oleksiy S.

    2009-01-01

    The stored energies, radiated power, and quality factor of a magnetic-dipole antenna, consisting of a spherical electrical surface current density enclosing a magnetic core, is obtained through direct spatial integration of the internally and externally radiated field expressed in terms of spheri...

  15. Helical Dipole Magnets for Polarized Protons in RHIC

    Science.gov (United States)

    Syphers, M.; Courant, E.; Fischer, W.; Luccio, A.; Mariam, F.; Peggs, S.; Pilat, F.; Roser, T.; Tepikian, S.; Tsoupas, N.; Willen, E.; Katayama, T.; Hatanaka, K.; Kawaguchi, T.; Okamura, M.; Tominaka, T.; Wu, H.; Ptitsin, V.; Shatunov, Y.

    1997-05-01

    The Brookhaven Relativistic Heavy Ion Collider (RHIC) will be able to support experiments using polarized proton beams. Siberian Snakes are used to maintain polarization in this high energy superconducting collider. To make efficient use of available space while taking advantage of high field superconducting magnets, 4 Tesla helical dipole magnets will be used. These magnets generate a central dipole field in which the field direction rotates through 360^circ about the longitudinal axis over the length of the device. An arrangement of four such magnets can produce the desired change in the spin direction while keeping the proton orbit outside of the ``Snake'' unaltered. Similar magnet arrangements will be used to produce longitudinal polarization at the two major interaction points in RHIC. The basic requirements and layout of these magnets are described, as well as tolerances on field quality and integrated field strengths. First results of tests of prototype helical magnets will be discussed.

  16. Constraining the neutrino magnetic dipole moment from white dwarf pulsations

    CERN Document Server

    Córsico, Alejandro H; Bertolami, Marcelo M Miller; Kepler, S O; García-Berro, Enrique

    2014-01-01

    Pulsating white dwarf stars can be used as astrophysical laboratories to constrain the properties of weakly interacting particles. Comparing the cooling rates of these stars with the expected values from theoretical models allows us to search for additional sources of cooling due to the emission of axions, neutralinos, or neutrinos with magnetic dipole moment. In this work, we derive an upper bound to the neutrino magnetic dipole moment using an estimate of the rate of period change of the pulsating DB white dwarf star PG 1351+489. By comparing the theoretical rate of change of period expected for this star with the rate of change of period with time of PG 1351+489, we assess the possible existence of additional cooling by neutrinos with magnetic dipole moment. Our models suggest the existence of some additional cooling in this pulsating DB white dwarf, consistent with a non-zero magnetic dipole moment. Our upper limit for the neutrino magnetic dipole moment is somewhat less restrictive than, but still compat...

  17. Design, manufacture and measurements of permanent dipole magnets for DIRAC

    CERN Document Server

    Vorozhtsov, A; Kasaei, S; Solodko, E; Thonet, P A; Tommasini, D

    2013-01-01

    The one of the aim of the DIRAC experiment is the observation of the long-lived π+π- atoms, using the proton beam of the CERN Proton Synchrotron [1]. Two dipole magnets are needed for the for the DIRAC experiment as high resolution spectrometers. The dipole magnet will be used to identify the long-lived atoms on the high level background of π+π- pairs produced simultaneously with π+π- atoms. The proposed design is a permanent magnet dipole with a mechanical aperture of 60 mm. The magnet, of a total physical length of 66 mm, is based on Sm2Co17 blocks and provides an integrated field strength of 24·10-3 T×m. The Sm2Co17 was chosen as a material for the permanent magnet blocks due to its radiation hardness and weaker temperature dependence. The magnetic field quality is determined by 2 ferromagnetic poles, aligned together with the permanent magnets blocks. The paper describes the design, manufacture and magnetic measurements of the magnets.

  18. The last LHC dipole magnet is lowered

    CERN Multimedia

    Claudia Marcelloni

    2007-01-01

    A ceremony is held as the last of 1746 superconducting magnets is lowered into the 27-km circumference tunnel that houses the LHC. The LHC project leader, Lyn Evans, changes a banner reading ‘first magnet for the LHC’ to ‘last magnet for the LHC’ in his native Welsh.

  19. Bistability between equatorial and axial dipoles during magnetic field reversals

    CERN Document Server

    Gissinger, Christophe; Schrinner, Martin; Dormy, Emmanuel

    2012-01-01

    Numerical simulations of the geodynamo in presence of an heterogeneous heating are presented. We study the dynamics and the structure of the magnetic field when the equatorial symmetry of the flow is broken. If the symmetry breaking is sufficiently strong, the m = 0 axial dipolar field is replaced by an hemispherical magnetic field, dominated by an oscillating m = 1 magnetic field. Moreover, for moderate symmetry breaking, a bistability between the axial and the equatorial dipole is observed. In this bistable regime, the axial magnetic field exhibits chaotic switches of its polarity, involving the equatorial dipole during the transition period. This new scenario for magnetic field reversals is discussed within the framework of the Earth's dynamo.

  20. Bistability between equatorial and axial dipoles during magnetic field reversals.

    Science.gov (United States)

    Gissinger, Christophe; Petitdemange, Ludovic; Schrinner, Martin; Dormy, Emmanuel

    2012-06-08

    Numerical simulations of the geodynamo in the presence of heterogeneous heating are presented. We study the dynamics and the structure of the magnetic field when the equatorial symmetry of the flow is broken. If the symmetry breaking is sufficiently strong, the m=0 axial dipolar field is replaced by a hemispherical magnetic field, dominated by an oscillating m=1 magnetic field. Moreover, for moderate symmetry breaking, a bistability between the axial and the equatorial dipole is observed. In this bistable regime, the axial magnetic field exhibits chaotic switches of its polarity, involving the equatorial dipole during the transition period. This new scenario for magnetic field reversals is discussed within the framework of Earth's dynamo.

  1. Quantum electrodynamical corrections to a magnetic dipole in general relativity

    CERN Document Server

    Pétri, J

    2015-01-01

    Magnetized neutron stars are privileged places where strong electromagnetic fields as high as $\\BQ=4.4\\times10^9$~T exist, giving rise to non-linear corrections to Maxwell equations described by quantum electrodynamics (QED). These corrections need to be included to the general relativistic (GR) description of a magnetic dipole supposed to be anchored in the neutron star. In this paper, these QED and GR perturbations to the standard flat space-time dipole are calculated to the lowest order in the fine structure constant~$\\alpha_{\\rm sf}$ and to any order in the ratio $\\Rs/R$ where $R$ is the neutron star radius and $\\Rs$ its Schwarzschild radius. Following our new 3+1~formalism developed in a previous work, we compute the multipolar non-linear corrections to this dipole and demonstrate the presence of a small dipolar~$\\ell=1$ and hexapolar~$\\ell=3$ component.

  2. Superconducting dipole magnet for the CBM experiment at FAIR

    Directory of Open Access Journals (Sweden)

    Kurilkin P.

    2017-01-01

    Full Text Available The scientific goal of the CBM (Compressed Baryonic Matter experiment at FAIR (Darmstadt is to explore the phase diagram of strongly interacting matter at highest baryon densities. The physics program of the CBM experiment is complimentary to the programs to be realized at MPD and BMN facilities at NICA and will start with beam derived by the SIS100 synchrotron. The 5.15 MJ superconducting dipole magnet will be used in the silicon tracking system of the CBM detector. The magnet will provide a magnetic field integral of 1 Tm which is required to obtain a momentum resolution of 1% for the track reconstruction. The results of the development of dipole magnet of the CBM experiment are presented.

  3. The permanent and induced magnetic dipole moment of the moon

    Science.gov (United States)

    Russell, C. T.; Coleman, P. J., Jr.; Lichtenstein, B. R.; Schubert, G.

    1974-01-01

    Magnetic field observations with the Apollo 15 subsatellite have been used to deduce the components of both the permanent and induced lunar dipole moments in the orbital plane. The present permanent lunar magnetic dipole moment in the orbital plane is less than 1.3 times ten to the eighteenth power gauss-cu cm. Any uniformly magnetized near surface layer is therefore constrained to have a thickness-magnetization product less than 2.5 emu-cm per g. The induced moment opposes the external field, implying the existence of a substantial lunar ionosphere with a permeability between 0.63 and 0.85. Combining this with recent measures of the ratio of the relative field strength at the ALSEP and Explorer 35 magnetometers indicates that the global lunar permeability relative to the plasma in the geomagnetic tail lobes is between 1.008 and 1.03.

  4. Optical dipole mirror for cold atoms based on a metallic diffraction grating

    DEFF Research Database (Denmark)

    Kawalec, Tomasz; Bartoszek-Bober, Dobroslawa; Panas, Roman

    We report on the realization of a plasmonic dipole mirror for cold atoms based on a metallic grating coupler. A cloud of atoms is reflected by the repulsive potential generated by surface plasmon polaritons (SPPs) excited on a reflection gold grating by a 780 nm laser beam. Experimentally...

  5. Optical dipole mirror for cold atoms based on a metallic diffraction grating

    DEFF Research Database (Denmark)

    Kawalec, Tomasz; Bartoszek-Bober, Dobroslawa; Panas, Roman

    2014-01-01

    We report on the realization of a plasmonic dipole mirror for cold atoms based on a metallic grating coupler. A cloud of atoms is reflected by the repulsive potential generated by surface plasmon polaritons (SPPs) excited on a reflection gold grating by a 780 nm laser beam. Experimentally...

  6. Constraining the neutrino magnetic dipole moment from white dwarf pulsations

    Energy Technology Data Exchange (ETDEWEB)

    Córsico, A.H.; Althaus, L.G. [Grupo de Evolución Estelar y Pulsaciones, Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, (1900) La Plata (Argentina); Bertolami, M.M. Miller [Instituto de Astrofísica La Plata, CONICET-UNLP, Paseo del Bosque s/n, (1900) La Plata (Argentina); Kepler, S.O. [Departamento de Astronomia, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, Porto Alegre 91501-970, RS (Brazil); García-Berro, E., E-mail: acorsico@fcaglp.unlp.edu.ar, E-mail: althaus@fcaglp.unlp.edu.ar, E-mail: marcelo@MPA-Garching.MPG.DE, E-mail: kepler@if.ufrgs.br, E-mail: enrique.garcia-berro@upc.edu [Departament de Física Aplicada, Universitat Politècnica de Catalunya, c/Esteve Terrades 5, 08860, Castelldefels (Spain)

    2014-08-01

    Pulsating white dwarf stars can be used as astrophysical laboratories to constrain the properties of weakly interacting particles. Comparing the cooling rates of these stars with the expected values from theoretical models allows us to search for additional sources of cooling due to the emission of axions, neutralinos, or neutrinos with magnetic dipole moment. In this work, we derive an upper bound to the neutrino magnetic dipole moment (μ{sub ν}) using an estimate of the rate of period change of the pulsating DB white dwarf star PG 1351+489. We employ state-of-the-art evolutionary and pulsational codes which allow us to perform a detailed asteroseismological period fit based on fully DB white dwarf evolutionary sequences. Plasmon neutrino emission is the dominant cooling mechanism for this class of hot pulsating white dwarfs, and so it is the main contributor to the rate of change of period with time (Pidot) for the DBV class. Thus, the inclusion of an anomalous neutrino emission through a non-vanishing magnetic dipole moment in these sequences notably influences the evolutionary timescales, and also the expected pulsational properties of the DBV stars. By comparing the theoretical Pidot value with the rate of change of period with time of PG 1351+489, we assess the possible existence of additional cooling by neutrinos with magnetic dipole moment. Our models suggest the existence of some additional cooling in this pulsating DB white dwarf, consistent with a non-zero magnetic dipole moment with an upper limit of μ{sub ν} ∼< 10{sup -11} μ{sub B}. This bound is somewhat less restrictive than, but still compatible with, other limits inferred from the white dwarf luminosity function or from the color-magnitude diagram of the Globular cluster M5. Further improvements of the measurement of the rate of period change of the dominant pulsation mode of PG 1351+489 will be necessary to confirm our bound.

  7. LHC dipole magnets start to roll off the production line

    CERN Multimedia

    2000-01-01

    The first pre-series LHC dipole magnet has been delivered to CERN, a further 1247 are due to be produced by 2005. Their production is the result of technology transfer from CERN to its suppliers. Fifteen metres long, thirty-tonnes in weight, and using several kilometres of superconducting cable, the magnet that has just arrived in hall 181 is a true colossus. It is the first pre-series dipole that will begin service in 2005 in the future Large Hadron Collider, LHC. Delivered by the French Alstom-Jeumont Industrie consortium, it is the first of 1248 magnets that will be manufactured over the coming five years. Needless to say, lavish attention has been devoted to this magnet by the engineers and technicians who accompanied it to CERN from Belfort in north east France. The task of the dipole magnets will be to steer the LHC's proton beams on a circular trajectory around the LHC's 27 kilometre circumference. A magnetic field of 8.33 Tesla is required to guide the protons, accelerated to an energy of 7 TeV, aroun...

  8. Retraining of the 1232 Main Dipole Magnets in the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Verweij, A. [CERN; Auchmann, B.; Bednarek, M.; Bottura, L.; Charifoulline, Z.; Feher, S. [Fermilab; Hagen, P.; Modena, M.; Le Naour, S.; Romera, I.; Siemko, A.; Steckert, J.; Tock, J. Ph; Todesco, E.; Willering, G.; Wollmann, D.

    2016-01-05

    The Large Hadron Collider (LHC) contains eight main dipole circuits, each of them with 154 dipole magnets powered in series. These 15-m-long magnets are wound from Nb-Ti superconducting Rutherford cables, and have active quench detection triggering heaters to quickly force the transition of the coil to the normal conducting state in case of a quench, and hence reduce the hot spot temperature. During the reception tests in 2002-2007, all these magnets have been trained up to at least 12 kA, corresponding to a beam energy of 7.1 TeV. After installation in the accelerator, the circuits have been operated at reduced currents of up to 6.8 kA, from 2010 to 2013, corresponding to a beam energy of 4 TeV. After the first long shutdown of 2013-2014, the LHC runs at 6.5 TeV, requiring a dipole magnet current of 11.0 kA. A significant number of training quenches were needed to bring the 1232 magnets up to this current. In this paper, the circuit behavior in case of a quench is presented, as well as the quench training as compared to the initial training during the reception tests of the individual magnets.

  9. Status of design, development and test of the dipole magnets for the high energy booster

    Energy Technology Data Exchange (ETDEWEB)

    Butler, J.M.; Boulios, G.; Finger, K.; Kaylor, L.; McConnon, A.; McConnon, S.; Osborne, S.; Sinnott, Z.; Pisz, F.; Swenson, C. [Westinghouse Magnet Systems Division, Round Rock, TX (United States)] [and others

    1994-12-31

    Westinghouse Magnet Systems Division has a contract to design, develop, build and test the superconducting dipole magnets for the High Energy Booster. This paper covers the key requirements of the magnet and the design features to meet these requirements. Although similar to the Collider dipole magnets, there are some key differences in the functional requirements and design constraints which lead to design differences. Most significant is the requirement to prevent quench during bipolar operation at a ramp rate of 62 A/s compared to unipolar operation at 4 A/s for the Collider. Testing of 50 mm magnets made for the SSCL string test show that the design is sensitive to interstrand eddy currents and resultant heating at the higher ramp rate. The cryostat diameter is not constrained by the fixed distance between top and bottom rings as in the Collider. The authors are taking advantage of the additional space allowed. Emphasis in this paper is placed on the design differences and the reasons for them in both the cold mass and the cryostat. The cold testing requirements and plans for test facilities to carry out the tests are summarized.

  10. Cold-atom physics using ultrathin optical fibers: light-induced dipole forces and surface interactions.

    Science.gov (United States)

    Sagué, G; Vetsch, E; Alt, W; Meschede, D; Rauschenbeutel, A

    2007-10-19

    The strong evanescent field around ultrathin unclad optical fibers bears a high potential for detecting, trapping, and manipulating cold atoms. Introducing such a fiber into a cold-atom cloud, we investigate the interaction of a small number of cold cesium atoms with the guided fiber mode and with the fiber surface. Using high resolution spectroscopy, we observe and analyze light-induced dipole forces, van der Waals interaction, and a significant enhancement of the spontaneous emission rate of the atoms. The latter can be assigned to the modification of the vacuum modes by the fiber.

  11. Low-Q Electrically Small Spherical Magnetic Dipole Antennas

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.

    2010-01-01

    Three novel electrically small antenna configurations radiating a TE10 spherical mode corresponding to a magnetic dipole are presented and investigated: multiarm spherical helix (MSH) antenna, spherical split ring resonator (S-SRR) antenna, and spherical split ring (SSR) antenna. All three antennas...... are self-resonant, with the input resistance tuned to 50 ohms by an excitation curved dipole/monopole. A prototype of the SSR antenna has been fabricated and measured, yielding results that are consistent with the numerical simulations. Radiation quality factors (Q) of these electrically small antennas (in...

  12. Effect of metallic and hyperbolic metamaterial surface on electric and magnetic dipole emission

    DEFF Research Database (Denmark)

    Ni, Xingjie; Naik, Gururaj V.; Kildishev, Alexander V.

    2010-01-01

    Spontaneous emission patterns of electric and magnetic dipoles on different material surfaces were studied numerically and experimentally. The results show the modified behavior of electric and magnetic dipoles on metallic and HMM surfaces.......Spontaneous emission patterns of electric and magnetic dipoles on different material surfaces were studied numerically and experimentally. The results show the modified behavior of electric and magnetic dipoles on metallic and HMM surfaces....

  13. Effect of metallic and hyperbolic metamaterial surface on electric and magnetic dipole emission

    DEFF Research Database (Denmark)

    Ni, Xingjie; Naik, Gururaj V.; Kildishev, Alexander V.;

    2010-01-01

    Spontaneous emission patterns of electric and magnetic dipoles on different material surfaces were studied numerically and experimentally. The results show the modified behavior of electric and magnetic dipoles on metallic and HMM surfaces.......Spontaneous emission patterns of electric and magnetic dipoles on different material surfaces were studied numerically and experimentally. The results show the modified behavior of electric and magnetic dipoles on metallic and HMM surfaces....

  14. A Mole for Warm Magnetic and Optical Measurements of LHC Dipoles

    CERN Document Server

    Bottura, L; Deferne, G; Glöckner, C; Jansen, H; Köster, A; Legrand, P; Rijllart, A; Sievers, P

    2000-01-01

    A new rotating coil probe (a mole) has been developed for the simultaneous measurement of the magnetic field and magnetic axis of warm superconducting LHC dipoles and associated corrector windings. The mole houses a radial rotating coil and travels inside the magnet aperture by means of an externally driven two-way traction belt. The coil is rotated by an on-board piezo motor, being tested in view of future devices for cold measurements as the only type of motor compatible with strong magnetic fields. A virtual light spot is generated in the coil center by a LED source. The position of this light spot is measured from the outside by a system including a telescope, a CCD camera and a DSP. Jigs on reference granite tables are used to transfer the optical measurements to the magnet fiducials. We describe here the main characteristics and performance of the mole

  15. Electron Cloud Trapping in Recycler Combined Function Dipole Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Antipov, Sergey A. [Chicago U.; Nagaitsev, S. [Fermilab

    2016-10-04

    Electron cloud can lead to a fast instability in intense proton and positron beams in circular accelerators. In the Fermilab Recycler the electron cloud is confined within its combined function magnets. We show that the field of combined function magnets traps the electron cloud, present the results of analytical estimates of trapping, and compare them to numerical simulations of electron cloud formation. The electron cloud is located at the beam center and up to 1% of the particles can be trapped by the magnetic field. Since the process of electron cloud build-up is exponential, once trapped this amount of electrons significantly increases the density of the cloud on the next revolution. In a Recycler combined function dipole this multiturn accumulation allows the electron cloud reaching final intensities orders of magnitude greater than in a pure dipole. The multi-turn build-up can be stopped by injection of a clearing bunch of 1010 p at any position in the ring.

  16. Retraining of the 1232 Main Dipole Magnets in the LHC

    CERN Document Server

    Verweij, A; Bednarek, M; Bottura, L; Charifoulline, Z; Feher, S; Hagen, P; Modena, M; Le Naour, S; Romera, I; Siemko, A; Steckert, J; Tock, J Ph; Todesco, E; Willering, G; Wollmann, D

    2016-01-01

    The Large Hadron Collider (LHC) contains eight main dipole circuits, each of them with 154 dipole magnets powered in series. These 15-m-long magnets are wound from Nb-Ti superconducting Rutherford cables, and have active quench detection triggering heaters to quickly force the transition of the coil to the normal conducting state in case of a quench, and hence reduce the hot spot temperature. During the reception tests in 2002-2007, all these magnets have been trained up to at least 12 kA, corresponding to a beam energy of 7.1 TeV. After installation in the accelerator, the circuits have been operated at reduced currents of up to 6.8 kA, from 2010 to 2013, corresponding to a beam energy of 4 TeV. After the first long shutdown of 2013-2014, the LHC runs at 6.5 TeV, requiring a dipole magnet current of 11.0 kA. A significant number of training quenches were needed to bring the 1232 magnets up to this current. In this paper, the circuit behavior in case of a quench is presented, as well as the quench training as...

  17. Slice of the LHC prototype beam tubes in dipole magnet

    CERN Multimedia

    1995-01-01

    A slice of the LHC accelerator prototype beam tubes surrounded by magnets. The LHC will accelerate two proton beams in opposite directions. The high bending and accelerating fields needed can only be reached using superconductors. At very low temperatures superconductors have no electrical resistance and therefore no power loss. The LHC will be the largest superconducting installation ever built, a unique challenge for CERN and its industrial partners. About dipole magnets: There will be 1232 dipole magnets in the LHC, used to guide the particles around the 27 km ring. Dipole magnets must have an extremely uniform field, which means the current flowing in the coils has to be very precisely controlled. Nowhere before has such precision been achieved at such high currents. The temperature is measured to five thousandths of a degree, the current to one part in a million. The current creating the magnetic field will pass through superconducting wires at up to 12 500 amps, about 30 000 times the current flowing ...

  18. Measurement of the Cold Dark Matter-Neutrino Dipole in the TianNu Simulation

    CERN Document Server

    Inman, Derek; Zhu, Hong-Ming; Emberson, J D; Pen, Ue-Li; Zhang, Tong-Jie; Yuan, Shuo; Chen, Xuelei; Xing, Zhi-Zhong

    2016-01-01

    Measurements of neutrino mass in cosmological observations rely on two point statistics that are hindered by significant degeneracies with the optical depth and galaxy bias. The relative velocity effect between cold dark matter and neutrinos induces a large scale dipole into the matter density field and may be able to provide orthogonal constraints to standard techniques. We numerically investigate this dipole in the TianNu Simulation, which contains cold dark matter and 50 meV neutrinos. We first compute the dipole using a new linear response technique where we treat the displacement caused by the relative velocity as a phase in Fourier space and then integrate the matter power spectrum over redshift. Then, we compute the dipole numerically in real space using the simulation density and velocity fields. We find excellent agreement between the linear response and N-body methods. Utilizing the dipole as an observational tool will require two tracers of the matter distribution that are differently biased with r...

  19. Optics effects of splitting dipole magnets into several thin lenses

    CERN Document Server

    Leunissen, L H A

    1998-01-01

    The evaluation of the dynamic aperture and the calculation of non linear optics parameters have been made so far with the simplest model of dipole, i.e. a single thin lens positioned at the centre of each thick dipole. It was shown recently that the non-linear chromaticity decreases significantly when the thick lens is represented by two thin lenses or more instead of one. In this note the study is extended to amplitude detuning and dynamic aperture. Unlike the observation reported on non-linear chromatic detuning we find no significant changes for the dynamic aperture and amplitude d etuning when the dipole magnets are split in more than one thin lens. Furthermore, non-uniform azimuthal distribution of the multipoles inside the dipole is shown not to change the above-mentio ned results. In both cases, the influence of the beta-funtions is expected to give large effect for a given dipole. However, integrated over one cell this effect is shown to compensate to a large extent. erture reported on non-linear chro...

  20. Coil end design for the SSC collider dipole magnet

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, J.; Bartlett, N.; Bossert, R.; Carson, J.; Konc, J.; Lee, G. [Fermi National Accelerator Lab., Batavia, IL (United States); Cook, J. [Argonne National Lab., IL (United States); Caspi, S. [Lawrence Berkeley Lab., CA (United States); Gordon, M.; Nobrega, F. [Superconducting Super Collider Lab., Dallas, TX (United States)

    1991-07-01

    This paper describes the design of the coil end for the 50mm aperture SSC collider dipole magnets built at Fermilab. The cable paths are determined from both magnetic and mechanical considerations. The end spacers are designed using the developable surface, grouped end approach, which allows the analysis of strain energy within the conductor groups. Techniques for strain energy minimization are presented and the behavior of individual conductors within a group is analyzed. The relationship between optimization of magnetic and mechanical variables is discussed. Requirements of manufacturing and inspection of coil end parts are outlined. 7 refs.

  1. Tests and Field Map of LHCb Dipole Magnet

    CERN Document Server

    Losasso, Marcello; Flegel, Wilfried; Giudici, Pierre-Ange; Hernando, Jose Angel; Jamet, Olivier; Lindner, Rolf; Renaud, Jean; Teubert, Frederic

    2005-01-01

    The LHCb experiment at the LHC at CERN is aimed to study CP violation and to measure the rare decays of B-mesons with exceptionally high precision. A 4 Tm dipole magnet is required for particle separation and momentum measurements. The 1600 ton warm magnet with sloping poles was installed and fully commissioned by the end of 2004. It is the first detector magnet of the four LHC experiments to have been aligned and commissioned in its final position. In this paper the magnet installation in the underground cavern of Point 8 and its alignment on the beam line are shortly reviewed. Results of a first magnetic field mapping in the region of the magnet poles and the fringe field in the location of the RICH detectors are presented. The mechanical equipment used for the automatic displacement of the Hall probe array is described together with the precision of the measurements obtained which are compared with TOSCA finite element calculations.

  2. Design and test of the benches for the magnetic measurement of the LHC dipoles

    Science.gov (United States)

    Billan, J.; Buckley, J.; Saban, R.; Sievers, P.; Walckiers, L.

    1994-07-01

    The magnetic measurement of more than 1300 LHC dipoles comprises the content of higher harmonic field components, field direction and field integrals. The measurements will be carried out along a warm bore installed inside the magnet cold bore, thus allowing the use of rotating coils at room temperature. This coil, together with Hall and NMR detectors is mounted at one end of a 12.5 m long shaft which is specially designed for very high rotational stiffness and which is controlled from its far end by a motor, an angular encoder and a level meter, all standard components placed outside the magnetic field without space restrictions. Particular emphasis has been put on the user-friendliness of the bench and its automated, computer-controlled operation requiring a minimum of staff, an important issue during production measurements of large series of magnets. The bench and its performance and precision achieved during its commissioning are described.

  3. Strongly magnetized rotating dipole in general relativity

    CERN Document Server

    Petri, J

    2016-01-01

    Electromagnetic waves arise in many area of physics. Solutions are difficult to find in the general case. In this paper, we numerically integrate Maxwell equations in a 3D spherical polar coordinate system. Straightforward finite difference methods would lead to a coordinate singularity along the polar axis. Spectral methods are better suited to deal with such artificial singularities related to the choice of a coordinate system. When the radiating object is rotating like for instance a star, special classes of solutions to Maxwell equations are worthwhile to study such as quasi-stationary regimes. Moreover, in high-energy astrophysics, strong gravitational and magnetic fields are present especially around rotating neutron stars. In order to study such systems, we designed an algorithm to solve the time-dependent Maxwell equations in spherical polar coordinates including general relativity as well as quantum electrodynamical corrections to leading order. As a diagnostic, we compute the spindown luminosity exp...

  4. Acceleration of magnetic dipoles by a sequence of current-carrying turns

    Science.gov (United States)

    Dolya, S. N.

    2014-11-01

    Magnetic dipoles are accelerated by a running gradient of the magnetic field that is produced by sequentially energizing current-carrying turns. Magnetic dipoles d sh = 60 mm in diameter and l tot = 1 m in length are gasdynamically preaccelerated to velocity V in = 1 km/s, with which they are injected into the main accelerator. The turnover of the dipoles in the field of an accelerating pulse is prevented and focusing of dipoles is provided by directing the dipoles into a titanium tube. The weight of the dipoles is m = 2 kg, and they acquire final velocity V fin = 5 km/s over acceleration length L acc = 300 m.

  5. Microscopic investigation of magnetic dipole bands in {sup 132}Ba

    Energy Technology Data Exchange (ETDEWEB)

    Higashiyama, Koji [Department of Physics, University of Tokyo, Hongo, Tokyo 113-0033 (Japan); Yoshinaga, Naotaka [Department of Physics, Saitama University, Saitama City 338-8570 (Japan)

    2005-10-01

    Nuclear structure of {sup 132}Ba is investigated within a framework of the pair-truncated shell model. The model reproduces experimental energy levels of the magnetic dipole band with the {nu}(h{sup 2}{sub 11/2}) x {pi}(h{sub 11/2}g{sub 7/2}) configuration. From the analysis of its structure, it turns out that two angular momenta of valence neutrons and protons gradually close as total spin increases.

  6. The magnetic dipole transitions in the (c) binding system

    Institute of Scientific and Technical Information of China (English)

    CHANG; ChaoHsi

    2010-01-01

    The magnetic dipole transitions between the vector mesons B-c and their relevant pseudoscalar mesons B c (B c ,B-c ,B c (2S ),B-c (2S ),B c (3S ),B-c (3S ) etc.,the binding states of (c) system) of the B c family are interesting.The ‘hyperfine’ splitting due to spin-spin interaction is an important topic for understanding the spin-spin interaction and the spectrum of the the (c) binding system.The knowledge about the magnetic dipole transitions is also very useful for identifying the vector boson B-c mesons experimentally,whose masses are just slightly above the masses of their relevant pseudoscalar mesons B c .Considering the possibility to observe the vector mesons via the transitions at Z 0 factory and the potential use of the theoretical estimate on the transitions,we fucus our efforts on calculating the magnetic dipole transitions,i.e.a precise calculation of the rates for the transitions such as decays B-c → B c γ and B-c → B c e + e-,and particularly work in the Bethe-Salpeter framework.As a typical example,we carefully investigate the dependence of the rate Γ(B-c → B c γ) on the mass difference ΔM = M B-c-M B c .

  7. Minimum Q Electrically Small Spherical Magnetic Dipole Antenna - Practice

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Breinbjerg, Olav

    2009-01-01

    resonances of all other modes that are not sufficiently suppressed in the antenna. Numerical results for a 4-arm spherical helix antenna filled with magnetic material demonstrate the destroying effect of the parasitic TM11 mode on the antenna Q factor. Theoretical considerations as well as numerical results......Practical aspects of applying a magnetic core to approach the Chu lower bound for the radiation Q factor of an electrically small magnetic dipole antenna are considered. It is shown that although a magnetic core does reduce the Q factor, its effect is not as strong as predicted by Wheeler...... show that in a given range of magnetic permeabilities away from core resonances there is an optimum permeability for which the Q factor is lowest. In the given example, the antenna of the size ka~0.254 yields the Q ratio 1.28 times above the Chu lower bound....

  8. Quantum-enhanced protocols with mixed states using cold atoms in dipole traps

    Science.gov (United States)

    Krzyzanowska, K.; Copley-May, M.; Romain, R.; MacCormick, C.; Bergamini, S.

    2017-01-01

    We discuss the use of cold atoms in dipole traps to demonstrate experimentally a particular class of protocols for computation and metrology based on mixed states. Modelling of the system shows that, for a specific class of problems (tracing, phase estimation), a quantum advantage can be achieved over classical algorithms for very realistic conditions and strong decoherence. We discuss the results of the models and the experimental implementation.

  9. Kick velocity induced by magnetic dipole and quadrupole radiation

    CERN Document Server

    Kojima, Yasufumi

    2010-01-01

    We examine the recoil velocity induced by the superposition of the magnetic dipole and quadrupole radiation from a pulsar/magnetar born with rapid rotation. The resultant velocity depends on not the magnitude, but rather the ratio of the two moments and their geometrical configuration. The model does not necessarily lead to high spatial velocity for a magnetar with a strong magnetic field, which is consistent with the recent observational upper bound. The maximum velocity predicted with this model is slightly smaller than that of observed fast-moving pulsars.

  10. Dipole-exchange spin waves in Fibonacci magnetic multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Milton Pereira, J. [Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, Campus do Pici, 60451-970 Fortaleza, Ceara (Brazil)]. E-mail: pereira@fisica.yfc.br; Costa Filho, R.N. [Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, Campus do Pici, 60451-970 Fortaleza, Ceara (Brazil)]. E-mail: rai@fisica.ufc.br

    2005-08-29

    A microscopic model is employed to calculate the spectrum of spin waves in quasiperiodic magnetic multilayers in the dipole-exchange regime. Results are presented for structures in which thin ferromagnetic films are separated by non-magnetic spacers following a Fibonacci sequence and extend previous magnetostatic calculations. The results show the splitting of the frequency bands and the mode mixing caused by the dipolar interaction between the films as a function of spacer thickness, as well as the fractal aspect of the spectrum induced by the non-periodic aspect of the structure.

  11. Comparative study between toroidal coordinates and the magnetic dipole field

    CERN Document Server

    Chávez-Alarcón, Esteban

    2012-01-01

    There is a similar behaviour between the toroidal coordinates and the dipole magnetic field produced by a circular loop. In this work we evaluate up to what extent the former can be used as a representation of the latter. While the tori in the toroidal coordinates have circular cross sections, those of the circular loop magnetic field are nearly elliptical ovoids, but they are very similar for large aspect ratios.The centres of the latter displace from the axis faster than the former. By making a comparison between tori of similar aspect ratios, we find quantitative criteria to evaluate the accuracy of the approximation.

  12. Tailoring magnetic energies to form dipole skyrmions and skyrmion lattices

    Science.gov (United States)

    Montoya, S. A.; Couture, S.; Chess, J. J.; Lee, J. C. T.; Kent, N.; Henze, D.; Sinha, S. K.; Im, M.-Y.; Kevan, S. D.; Fischer, P.; McMorran, B. J.; Lomakin, V.; Roy, S.; Fullerton, E. E.

    2017-01-01

    The interesting physics and potential memory technologies resulting from topologically protected spin textures such as skyrmions have prompted efforts to discover new material systems that can host these kinds of magnetic structures. Here, we use the highly tunable magnetic properties of amorphous Fe/Gd multilayer films to explore the magnetic properties that lead to dipole-stabilized skyrmions and skyrmion lattices that form from the competition of dipolar field and exchange energy. Using both real space imaging and reciprocal space scattering techniques, we determined the range of material properties and magnetic fields where skyrmions form. Micromagnetic modeling closely matches our observation of small skyrmion features (˜50 to 70 nm) and suggests that these classes of skyrmions have a rich domain structure that is Bloch-like in the center of the film and more Néel-like towards each surface. Our results provide a pathway to engineer the formation and controllability of dipole skyrmion phases in a thin film geometry at different temperatures and magnetic fields.

  13. Magnetic field (B) and voltage (U) characteristics of the ALICE dipole magnet.

    CERN Multimedia

    2005-01-01

    The dipole magnet ready for testing, on 7 July the first current was injected. Ramping up to full current of 6 kA followed without any problem on 8 July. Then on 14 July, having operated without interruption at full current for more than 24 hours, the magnet was switched off until the start of the magnetic measurements.

  14. Decreasing the radiation quality factor of magnetic dipole antennas by a magnetic-coated metal core

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Breinbjerg, Olav

    2010-01-01

    To achieve the Chu lower bound for the radiation Q, an electrically small magnetic dipole antenna should not store any magnetic energy internally to the minimum sphere enclosing the antenna. As shown in our previous works, the internal stored magnetic energy can be reduced, although not entirely...

  15. Statistical Analysis of Conductor Motion in LHC Superconducting Dipole Magnets

    CERN Document Server

    Calvi, M; Pugnat, P; Siemko, A

    2004-01-01

    Premature training quenches are usually caused by the transient energy release within the magnet coil as it is energised. The dominant disturbances originate in cable motion and produce observable rapid variation in voltage signals called spikes. The experimental set up and the raw data treatment to detect these phenomena are briefly recalled. The statistical properties of different features of spikes are presented like for instance the maximal amplitude, the energy, the duration and the time correlation between events. The parameterisation of the mechanical activity of magnets is addressed. The mechanical activity of full-scale prototype and first preseries LHC dipole magnets is analysed and correlations with magnet manufacturing procedures and quench performance are established. The predictability of the quench occurrence is discussed and examples presented.

  16. Low-cost, pseudo-Halbach dipole magnets for NMR

    Science.gov (United States)

    Tayler, Michael C. D.; Sakellariou, Dimitrios

    2017-04-01

    We present designs for compact, inexpensive and strong dipole permanent magnets aimed primarily at magnetic resonance applications where prepolarization and detection occur at different locations. Low-homogeneity magnets with a 7.5 mm bore size and field up to nearly 2 T are constructed using low-cost starting materials, standard workshop tools and only few hours of labor - an achievable project for a student or postdoc with spare time. As an application example we show how our magnet was used to polarize the nuclear spins in approximately 1 mL of pure [13C ]-methanol prior to detection of its high-resolution NMR spectrum at zero field (measurement field below 10-10 T), where signals appear at multiples of the carbon-hydrogen spin-spin coupling frequency 1JCH = 140.7 (1) Hz.

  17. A magnetic guide for cold atoms

    CERN Document Server

    Richmond, J A; Cantwell, B P; Opat, G I

    1998-01-01

    We propose a novel method for guiding cold, neutral atoms using static magnetic fields. A theoretical study of the magnetic field produced by a tube consisting of two identical, interwound solenoids carrying equal but opposite currents is presented. This field is almost zero throughout the centre of the tube, but it increases with exponential rapidity as one approaches the walls formed by the current carrying wires. Hence, cold atoms passing through the tube may be reflected by magnetic mirror effects near the walls. Applying this technique to a free-falling cloud of magneto-optically cooled caesium atoms we hope to construct atomic guides to facilitate the manipulation of cold atomic beams.

  18. Pulsar Pair Cascades in a Distorted Magnetic Dipole Field

    CERN Document Server

    Harding, Alice K

    2010-01-01

    We investigate the effect of a distorted neutron star dipole magnetic field on pulsar pair cascade multiplicity and pair death lines. Using a simple model for a distorted dipole field that produces an offset polar cap, we derive the accelerating electric field above the polar cap in space charge limited flow. We find that even a modest azimuthally asymmetric distortion can significantly increase the accelerating electric field on one side of the polar cap and, combined with a smaller field line radius of curvature, leads to larger pair multiplicity. The death line for producing pairs by curvature radiation moves downward in the P-Pdot diagram, allowing high pair multiplicities in a larger percentage of the radio pulsar population. These results could have important implications for the radio pulsar population, high energy pulsed emission and the pulsar contribution to cosmic ray positrons.

  19. Electric charge is a magnetic dipole when placed in a background magnetic field

    CERN Document Server

    Adorno, T C; Shabad, A E

    2014-01-01

    It is demonstrated, owing to the nonlinearity of QED, that a static charge placed in a strong magnetic field\\ $B$\\ is a magnetic dipole (besides remaining an electric monopole, as well). Its magnetic moment grows linearly with $B$ as long as the latter remains smaller than the characteristic value of $1.2\\cdot 10^{13}\\unit{G}$ but tends to a constant as $B$ exceeds that value. The force acting on a densely charged object by the dipole magnetic field of a neutron star is estimated.

  20. Interaction between an electric charge and a magnetic dipole of any kind (permanent, para- or dia- magnetic or superconducting)

    CERN Document Server

    Coïsson, R

    2015-01-01

    The interaction between point charge and magnetic dipole is usually considered only for the case of a rigid ferromagnetic dipole (constant-current): here the analysis of force, momentum and energy (including the energy provided by the internal current generator) is generalised to any magnetic dipole behaviour: rigid, paramagnetic, diamagnetic or superconducting (perfectly diamagnetic).

  1. Measurement of the magnetic-field parameters of the NICA Booster dipole magnet

    Science.gov (United States)

    Kostromin, S. A.; Borisov, V. V.; Bichkov, A. V.; Golubitsky, O. M.; Donyagin, A. N.; Morozov, N. A.; Samsonov, E. V.; Omelyanenko, M. M.; Khodzhibagiyan, H. G.; Shemchuk, A. V.

    2016-12-01

    Serial assembly and tests of dipole and quadrupole magnets of the NICA Booster have started at the Laboratory of High Energy Physics of the Joint Institute for Nuclear Research (JINR). The accelerator is fitted with Nuclotron-type magnets with a superconducting winding and an iron yoke for shaping the needed magnetic field. The design of magnets for NICA was optimized (based on the experience gained in constructing and operating the JINR Nuclotron) for the production of magnetic fields of the required configuration in terms of the beam dynamics in the accelerator and the collider. Measurements of parameters of the field of each magnet are expected to be performed in the process of assembly and testing of each module of the magnet-cryostat system of the NICA Booster and Collider. The results of magnetic measurements for the NICA Booster dipole magnet are presented.

  2. Birotor dipole for Saturn's inner magnetic field from Cassini observations

    Science.gov (United States)

    Galopeau, Patrick

    2017-04-01

    The radio and plasma wave science (RPWS) experiment on board the Cassini spacecraft, orbiting around Saturn since July 2004, revealed the presence of two distinct and variable rotation periods in the Saturnian kilometric radiation (SKR). These two periods were attributed to the northern and southern hemispheres respectively. We suppose that the periodic time modulations present in the SKR are mainly due to the rotation of Saturn's inner magnetic field. The existence of a double period implies that the inner field is not only limited to a simple rotation dipole but displays more complex structures having the same time periodicities than the radio emission. In order to build a model of this complex magnetic field, it is absolutely necessary to know the accurate phases of rotation linked with the two periods. The radio observations from the RPWS experiment allow a continuous and accurate follow-up of these rotation phases, since the SKR emission is permanently observable and produced very close to the planetary surface. A continuous wavelet transform analysis of the intensity of the SKR signal received at 290 kHz between July 2004 and June 2012 was performed in order to calculate in the same time the different periodicities and phases. A dipole model was proposed for Saturn's inner magnetic field: this dipole presents the particularity to have North and South poles rotating around Saturn's axis at two different angular velocities; this dipole is tilted and not centered. 57 Cassini's revolutions, the periapsis of which is less than 5 Saturnian radii, have been selected for this study. For each of these chosen orbits, it is possible to fit with high precision the measurements of the MAG data experiment given by the magnetometers embarked on board Cassini. A nonrotating external magnetic field completes the model. This study suggests that Saturn's inner magnetic field is neither stationary nor fully axisymmetric. These results can be used as a boundary condition for

  3. Cold and ultracold NH--NH collisions in magnetic fields

    CERN Document Server

    Janssen, Liesbeth M C; van der Avoird, Ad; Groenenboom, Gerrit C; Hutson, Jeremy M

    2010-01-01

    Elastic and spin-changing inelastic collision cross sections are presented for cold and ultracold magnetically trapped NH. The cross sections are obtained from coupled-channel scattering calculations as a function of energy and magnetic field. We specifically investigate the influence of the intramolecular spin-spin, spin-rotation, and intermolecular magnetic dipole coupling on the collision dynamics. It is shown that $^{15}$NH is a very suitable candidate for evaporative cooling experiments. The dominant trap-loss mechanism in the ultracold regime originates from the intermolecular dipolar coupling term. At higher energies and fields, intramolecular spin-spin coupling becomes increasingly important. Our qualitative results and conclusions are fairly independent of the exact form of the potential and of the size of the channel basis set.

  4. Conformation-Selective Resonant Photoelectron Spectroscopy via Dipole-Bound States of Cold Anions.

    Science.gov (United States)

    Huang, Dao-Ling; Liu, Hong-Tao; Ning, Chuan-Gang; Wang, Lai-Sheng

    2015-06-18

    Molecular conformation is important in chemistry and biochemistry. Conformers connected by low energy barriers can only be observed at low temperatures and are difficult to be separated. Here we report a new method to obtain conformation-selective spectroscopic information about dipolar molecular radicals via dipole-bound excited states of the corresponding anions cooled in a cryogenic ion trap. We observed two conformers of cold 3-hydroxyphenoxide anions [m-HO(C6H4)O(-)] in high-resolution photoelectron spectroscopy and measured different electron affinities, 18,850(8) and 18,917(5) cm(-1), for the syn and anti 3-hydroxyphenoxy radicals, respectively. We also observed dipole-bound excited states for m-HO(C6H4)O(-) with different binding energies for the two conformers due to the different dipole moments of the corresponding 3-hydroxyphenoxy radicals. Excitations to selected vibrational levels of the dipole-bound states result in conformation-selective photoelectron spectra. This method should be applicable to conformation-selective spectroscopic studies of any anions with dipolar neutral cores.

  5. Beam induced electron cloud resonances in dipole magnetic fields

    Science.gov (United States)

    Calvey, J. R.; Hartung, W.; Makita, J.; Venturini, M.

    2016-07-01

    The buildup of low energy electrons in an accelerator, known as electron cloud, can be severely detrimental to machine performance. Under certain beam conditions, the beam can become resonant with the cloud dynamics, accelerating the buildup of electrons. This paper will examine two such effects: multipacting resonances, in which the cloud development time is resonant with the bunch spacing, and cyclotron resonances, in which the cyclotron period of electrons in a magnetic field is a multiple of bunch spacing. Both resonances have been studied directly in dipole fields using retarding field analyzers installed in the Cornell Electron Storage Ring. These measurements are supported by both analytical models and computer simulations.

  6. Quantum Dynamics of Magnetic and Electric Dipoles and Berry's Phase

    CERN Document Server

    Furtado, C; Furtado, Claudio

    2003-01-01

    We study the quantum dynamics of neutral particle that posseses a permanent magnetic and electric dipole moments in the presence of an electromagnetic field. The analysis of this dynamics demonstrates the appearance of a quantum phase that combines the Aharonov-Casher effect and the He-Mckellar-Wilkens effect. We demonstrate that this phase is a special case of the Berry's quantum phase. A series of field configurations where this phase would be found are presented. A generalized Casella-type effect is found in one these configurations. A physical scenario for the quantum phase in an interferometric experiment is proposed.

  7. Far-field resonance fluorescence from a dipole-interacting laser-driven cold atomic gas

    Science.gov (United States)

    Jones, Ryan; Saint, Reece; Olmos, Beatriz

    2017-01-01

    We analyze the temporal response of the fluorescence light that is emitted from a dense gas of cold atoms driven by a laser. When the average interatomic distance is comparable to the wavelength of the photons scattered by the atoms, the system exhibits strong dipolar interactions and collective dissipation. We solve the exact dynamics of small systems with different geometries and show how these collective features are manifest in the scattered light properties such as the photon emission rate, the power spectrum and the second-order correlation function. By calculating these quantities beyond the weak (linear) driving limit, we make progress in understanding the signatures of collective behavior in these many-body systems. Furthermore, we shed light on the role of disorder and averaging on the resonance fluorescence, of direct relevance for recent experimental efforts that aim at the exploration of many-body effects in dipole-dipole interacting gases of atoms.

  8. Services for a large warm spectrometer magnet : the LHC dipole magnet

    CERN Document Server

    Ridewood, J

    2005-01-01

    A summary of the general service requirements for a large warm dipole magnet and the challenges and issues associated with their installation will be presented. The LHCb spectrometer magnet will be used as an example, covering principally the power supply, cabling and cooling water system from conception to realisation and commissioning.

  9. Production of Austenitic Steel for the LHC Superconducting Dipole Magnets

    CERN Document Server

    Bertinelli, F; Komori, T; Peiro, G; Rossi, L

    2006-01-01

    The austenitic-steel collars are an important component of the LHC dipole magnets, operating at cryogenic temperature under high mechanical stress. The required steel, known as YUS 130S, has been specifically developed for this application by Nippon Steel Corporation (NSC), who was awarded a CERN contract in 1999 for the supply of 11 500 tonnes. In 2005 - after six years of work - the contract is being successfully completed, with final production being ensured since October 2003 by Nippon Steel & Sumikin Stainless Steel Corporation (NSSC). The paper describes the steel properties, its manufacturing and quality control process, organization of production, logistics and contract follow-up. Extensive statistics have been collected relating to mechanical, physical and technological parameters. Specific attention is dedicated to measurements of magnetic permeability performed at cryogenic temperatures by CERN, the equipment used and statistical results. Reference is also made to the resulting precision of the...

  10. Field quality of the LHC dipole magnets in operating conditions

    CERN Document Server

    Bottura, L; Fartoukh, Stéphane David; Russenschuck, Stephan; Sanfilippo, S; Scandale, Walter; Schmidt, F; Todesco, Ezio; Walckiers, L; Wolf, R

    2002-01-01

    We report here the main results of the field measurements performed so far on the pre-series LHC superconducting dipoles at superfluid helium temperature. After discussing the results at injection and collision conditions, we focus on the non-linear contributions at high field, on the contribution of superconductor magnetization at injection, and on ramp rate effects. The statistics accumulated on the first magnets of the production verify the hypotheses that have been used to design the correctors scheme for the LHC. In particular high field saturation is in line with the expectations, although a small systematic deformation due to Lorentz forces affects both sextupole and decapole terms. The decay at injection and snap-back at beginning of beam acceleration require careful characterization.

  11. LHC Dipole Axis, Spool Piece Alignment and Field Angle in Warm and Cold Conditions

    CERN Document Server

    Coccoli, M; García-Pérez, J

    2004-01-01

    The installation and commissioning of LHC requires knowledge of the magnetic alignment of the spool piece correctors mounted on the dipole end plates are, as well as of the dipole main field direction. The installation is based on the use of geometric information derived from mechanical measurements performed in warm conditions, assuming that geometric and magnetic axes coincide, and that thermal contractions of the assembly are homothetic. A series of measurements has been performed at room and superfluid Helium temperature to validate these assumptions. In this paper, a statistical analysis of the correlations obtained is presented for both corrector alignment and main field direction, and the results are compared with beam optics-based specifications.

  12. Strong dipole magnetic fields in fast rotating fully convective stars

    Science.gov (United States)

    Shulyak, D.; Reiners, A.; Engeln, A.; Malo, L.; Yadav, R.; Morin, J.; Kochukhov, O.

    2017-08-01

    M dwarfs are the most numerous stars in our Galaxy, with masses between approximately 0.5 and 0.1 solar masses. Many of them show surface activity qualitatively similar to our Sun and generate flares, high X-ray fluxes and large-scale magnetic fields1,2,3,4. Such activity is driven by a dynamo powered by the convective motions in their interiors2,5,6,7,8. Understanding properties of stellar magnetic fields in these stars finds a broad application in astrophysics, including theory of stellar dynamos and environment conditions around planets that may be orbiting these stars. Most stars with convective envelopes follow a rotation-activity relationship where various activity indicators saturate in stars with rotation periods shorter than a few days2,6,8. The activity gradually declines with rotation rate in stars rotating more slowly. It is thought that, due to a tight empirical correlation between X-ray radiance and magnetic flux9, the stellar magnetic fields will also saturate, to values around 4 kG (ref. 10). Here we report the detection of magnetic fields above the presumed saturation limit in four fully convective M dwarfs. By combining results from spectroscopic and polarimetric studies, we explain our findings in terms of bistable dynamo models11,12: stars with the strongest magnetic fields are those in a dipole dynamo state, whereas stars in a multipole state cannot generate fields stronger than about 4 kG. Our study provides observational evidence that the dynamo in fully convective M dwarfs generates magnetic fields that can differ not only in the geometry of their large-scale component, but also in the total magnetic energy.

  13. Effects of dipole-dipole interaction between cigar-shaped BECs of cold alkali atoms: towards inverse-squared interactions.

    Science.gov (United States)

    Yu, Yue; Luo, Zhuxi; Wang, Ziqiang

    2014-07-30

    We show that the dipole-dipole coupling between Wannier modes in cigar-shaped Bose-Einstein condensates (BECs) is significantly enhanced while the short-range coupling is strongly suppressed. As a result, the dipole-dipole interaction can become the dominant interaction between ultracold alkali Bose atoms. In the long length limit of a cigar-shaped BEC, the resulting effective one-dimensional models possess an effective inverse squared interacting potential, the Calogero-Sutherland potential, which plays a fundamental role in many fields of contemporary physics; but its direct experimental realization has been a challenge for a long time. We propose to realize the Calogero-Sutherland model in ultracold alkali Bose atoms and study the effects of the dipole-dipole interaction.

  14. MAGNETIC MODELING VS MEASUREMENTS OF THE DIPOLES FOR THE JLAB 10 KW FREE ELECTRON LASER UPGRADE

    Energy Technology Data Exchange (ETDEWEB)

    David Douglas; Robin Wines; Tom Hiatt; George Biallas; Kenneth Baggett; T.J. Schultheiss; V.A. Christina; J.W. Rathke; A. Smirnov; D. Newsham; Y. Luo; D. Yu

    2003-05-01

    Magnetic measurements of the six families of dipoles for the infrared Free Electron Laser Upgrade at the Thomas Jefferson National Accelerator Facility (Jlab) are compared to the magnetic models on which their design is based. The magnets were designed in parallel by three organizations. They used ANSYS, Radia or Opera 3D as a 3D magnetic modeling program. Comparison of the discrepancies between model and magnet measurement is presented along with analysis of their potential causes. These dipoles operate in two field ranges. The Injector/ Extractor Dipoles operate around 0.05 T and the Arc Dipoles and Optical Chicane Dipoles operate between 0.22 to 0.71 T. All magnets are required to meet core field and field integral flatness to parts in 104 over their good field region.

  15. Proposal for the award of a contract for the supply of austenitic steel strips for non-magnetic laminations of the LHC superconducting dipole magnets

    CERN Document Server

    1999-01-01

    This document concerns the award of a contract for the supply of 2 400 tonnes of cold-rolled austenitic steel strips for non-magnetic laminations of the cold mass of the LHC superconducting dipole magnets. Following a market survey carried out among 32 firms in fourteen Member States and two firms in Japan, a call for tenders (IT-2617/LHC/LHC) was sent on 3 June 1999 to three firms in two Member States and two firms in Japan. The Council agreed to the Management?s proposal to invite Japanese industry to participate, where appropriate, in calls for tenders for supplies for the LHC Project (CERN/CC/2110). By the closing date, CERN had received four tenders. The Finance Committee is invited to approve the negotiation of a contract with the firm KAWASAKI STEEL (JP), the lowest bidder complying with the technical specification, for the supply of 2 400 tonnes of cold-rolled austenitic steel for non-magnetic laminations of the cold mass of the LHC superconducting dipole magnets for a total amount of 1 277 856 000 Ja...

  16. Regular and chaotic orbits near a massive magnetic dipole

    CERN Document Server

    Kovář, Jiří; Karas, Vladimí; Kojima, Yasufumi; 10.1088/0264-9381/30/2/025010

    2013-01-01

    Within the framework of Bonnor's exact solution describing a massive magnetic dipole, we study the motion of neutral and electrically charged test particles. In dependence on the Bonnor spacetime parameters, we determine regions enabling the existence of stable circular orbits confined to the equatorial plane and of those levitating above the equatorial plane. Constructing Poincar\\'e surfaces of section and recurrence plots, we also investigate the dynamics of particles moving along general off-equatorial trajectories bound in effective potential wells forming around the stable circular orbits. We demonstrate that the motion in the Bonnor spacetime is not integrable. This extends previous investigations of generalized St\\"ormer's problem into the realm of exact solutions of Einstein-Maxwell equations, where the gravitational and electromagnetic effects play a comparable role on the particle motion.

  17. An equivalent magnetic dipoles model for quantitative damage recognition of broken wire

    Institute of Scientific and Technical Information of China (English)

    TAN Ji-wen; ZHAN Wei-xia; LI Chun-jing; WEN Yan; SHU Jie

    2005-01-01

    By simplifying saturatedly magnetized wire-rope to magnetic dipoles of the same magnetic field strength, an equivalent magnetic dipoles model is developed and the measuring principle for recognising damage of broken wire was presented. The relevant calculation formulas were also deduced. A composite solution method about nonlinear optimization was given. An example was given to illustrate the use of the equivalent magnetic dipoles method for quantitative damage recognition, and demonstrates that the result of this method is consistent with the real situation, so the method is valid and practical.

  18. Quality factor of an electrically small magnetic dipole antenna with magneto-dielectric core

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Breinbjerg, Olav

    2010-01-01

    In this work, we investigate the radiation Q of electrically small magnetic dipole antennas with magneto-dielectric core versus the antenna electrical size, permittivity and permeability of the core. The investigation is based on the exact theory for a spherical magnetic dipole antenna...

  19. LHC dipoles flood into CERN : the dipole nr 154 crowns the efforts of the LHC teams for increasing the fabrication rate of the magnets.

    CERN Multimedia

    Maximilien Brice

    2003-01-01

    On 3 December the "tableau" on the 4th floor in building 30 indicated 1078 dipoles to completion - or in other words, 154 dipoles had by this day been delivered to CERN, enough to complete the first octant of the machine. CERN has also now received enough superconducting cable - the "heart" of the magnets - for 600 dipoles, nearly half the total number of 1232.

  20. ANALYTICAL CALCULATION OF STOKES PROFILES OF ROTATING STELLAR MAGNETIC DIPOLE

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Gonzalez, M. J. [Instituto de Astrofisica de Canarias, Via Lactea s/n, 38200 La Laguna, Tenerife (Spain); Asensio Ramos, A. [Departamento de Astrofisica, Universidad de La Laguna, E-38205 La Laguna, Tenerife (Spain)

    2012-08-20

    The observation of the polarization emerging from a rotating star at different phases opens up the possibility to map the magnetic field in the stellar surface thanks to the well-known Zeeman-Doppler imaging. When the magnetic field is sufficiently weak, the circular and linear polarization profiles locally in each point of the star are proportional to the first and second derivatives of the unperturbed intensity profile, respectively. We show that the weak-field approximation (for weak lines in the case of linear polarization) can be generalized to the case of a rotating star including the Doppler effect and taking into account the integration on the stellar surface. The Stokes profiles are written as a linear combination of wavelength-dependent terms expressed as series expansions in terms of Hermite polynomials. These terms contain the surface-integrated magnetic field and velocity components. The direct numerical evaluation of these quantities is limited to rotation velocities not larger than eight times the Doppler width of the local absorption profiles. Additionally, we demonstrate that in a rotating star, the circular polarization flux depends on the derivative of the intensity flux with respect to the wavelength and also on the profile itself. Likewise, the linear polarization depends on the profile and on its first and second derivatives with respect to the wavelength. We particularize the general expressions to a rotating dipole.

  1. Dipole magnet of synchrotron source for national synchrotron centre of Ukraine

    CERN Document Server

    Gladkikh, P I; Muratov, V I; Peev, F A

    2001-01-01

    The paper contains the revised design of a dipole magnet for a synchrotron radiation source.Usage of such a magnet allows to reach the energy of electrons in a ring up to 1.2 GeV.In paper the result of simulation of a magnet for all modes of operations of a source are shown.The proposed variant of the dipole magnet considerably raises parameters of the synchrotron radiation source.

  2. Unveiling Magnetic Dipole Radiation in Phase-Reversal Leaky-Wave Antennas

    CERN Document Server

    Gupta, Shulabh; Caloz, Christophe

    2014-01-01

    The radiation principle of travelling-wave type phase-reversal antennas is explained in details, unveiling the presence of magnetic-dipole radiation in addition to well-known electric dipole radiation. It is point out that such magnetic dipole radiation is specific to the case of traveling-wave phase-reversal antennas whereas only electric-dipole radiation exists in resonant-type phase-reversal antennas. It is shown that a phase-reversal travelling-wave antenna alternately operates as an array of magnetic dipoles and an array of electric-dipoles during a time-harmonic period. This radiation mechanism is confirmed through both full-wave and experimental results.

  3. Measurement of the zero-field magnetic dipole moment of magnetizable colloidal silica spheres

    Energy Technology Data Exchange (ETDEWEB)

    Claesson, E M; Erne, B H; Bakelaar, I A; Kuipers, B W M; Philipse, A P [Van' t Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute, Utrecht University, Padualaan 8, 3584 CH Utrecht (Netherlands)

    2007-01-24

    The magnetic properties of dispersions of magnetic silica microspheres have been investigated by measuring the magnetization curves and the complex magnetic susceptibility as a function of frequency and field amplitude. The silica spheres appear to have a net permanent magnetic dipole moment, even in zero field, which is increased significantly after a temporary exposure of the silica colloids to a saturating magnetic field. The magnetic properties of the microparticles in zero field are discussed in terms of the number and the orientations of the embedded nanoparticle dipoles along an easy axis of magnetization in the absence of an external field.

  4. Measurement of the zero-field magnetic dipole moment of magnetizable colloidal silica spheres

    NARCIS (Netherlands)

    Claesson, E.M.; Erne, B.H.; Bakelaar, I.A.; Kuipers, B.W.M.; Philipse, A.P.

    2007-01-01

    The magnetic properties of dispersions of magnetic silica microspheres have been investigated by measuring the magnetization curves and the complex magnetic susceptibility as a function of frequency and field amplitude. The silica spheres appear to have a net permanent magnetic dipole moment, even i

  5. Design of self-correction coils in a superferric dipole magnet

    Indian Academy of Sciences (India)

    K Ruwali; K Hosoyama

    2012-05-01

    Design of self-correction coils in a superferric dipole magnet is carried out. By adopting the self-correction coil (SCC) scheme, we can do online correction of unwanted fields inside the magnet aperture during the whole operating cycle irrespective of their origin. The self-correction coils are short-circuited superconducting coils of required symmetry placed in the useful aperture of the AC dipole magnet. Design and operation mechanism of self-correction coils in a superferric dipole magnet are discussed in this paper.

  6. Polarization of Magnetic Dipole Emission and Spinning Dust Emission from Magnetic Nanoparticles

    CERN Document Server

    Hoang, Thiem

    2015-01-01

    Magnetic dipole emission (MDE) from interstellar magnetic nanoparticles is an important Galactic foreground in the microwave frequencies, and its polarization level may pose great challenges for achieving reliable measurements of cosmic microwave background (CMB) B-mode signal. To obtain theoretical constraints on the polarization of MDE, we first compute the degree of alignment of big silicate grains incorporated with magnetic inclusions. We find that, in realistic conditions of the interstellar medium, thermally rotating big grains with magnetic inclusions are weakly aligned and achieve {\\it alignment saturation} when the magnetic alignment rate becomes much faster than the rotational damping rate. We then compute the degree of alignment for free-flying magnetic nanoparticles, taking into account various interaction processes of grains with the ambient gas and radiation field, including neutral collisions, ion collisions, and infrared emission. We find that the rotational damping by infrared emission can si...

  7. Direct detection of light anapole and magnetic dipole DM

    Energy Technology Data Exchange (ETDEWEB)

    Nobile, Eugenio Del; Gelmini, Graciela B.; Huh, Ji-Haeng [Department of Physics and Astronomy, UCLA, 475 Portola Plaza, Los Angeles, CA 90095 (United States); Gondolo, Paolo, E-mail: delnobile@physics.ucla.edu, E-mail: gelmini@physics.ucla.edu, E-mail: paolo.gondolo@utah.edu, E-mail: jhhuh@physics.ucla.edu [Department of Physics and Astronomy, University of Utah, 115 South 1400 East #201, Salt Lake City, UT 84112 (United States)

    2014-06-01

    We present comparisons of direct detection data for ''light WIMPs'' with an anapole moment interaction (ADM) and a magnetic dipole moment interaction (MDM), both assuming the Standard Halo Model (SHM) for the dark halo of our galaxy and in a halo-independent manner. In the SHM analysis we find that a combination of the 90% CL LUX and CDMSlite limits or the new 90% CL SuperCDMS limit by itself exclude the parameter space regions allowed by DAMA, CoGeNT and CDMS-II-Si data for both ADM and MDM. In our halo-independent analysis the new LUX bound excludes the same potential signal regions as the previous XENON100 bound. Much of the remaining signal regions is now excluded by SuperCDMS, while the CDMSlite limit is much above them. The situation is of strong tension between the positive and negative search results both for ADM and MDM. We also clarify the confusion in the literature about the ADM scattering cross section.

  8. Vibrational Spectroscopy of Transient Dipolar Radicals via Autodetachment of Dipole-Bound States of Cold Anions

    Science.gov (United States)

    Huang, Dao-Ling; Liu, Hong-Tao; Dau, Phuong Diem; Wang, Lai-Sheng

    2014-06-01

    High-resolution vibrational spectroscopy of transient species is important for determining their molecular structures and understanding their chemical reactivity. However, the low abundance and high reactivity of molecular radicals pose major challenges to conventional absorption spectroscopic methods. The observation of dipole-bound states (DBS) in anions extend autodetachment spectroscopy to molecular anions whose corresponding neutral radicals possess a large enough dipole moment (>2.5 D).1,2 However, due to the difficulty of assigning the congested spectra at room temperature, there have been only a limited number of autodetachment spectra via DBS reported. Recently, we have built an improved version of a cold trap3 coupled with high-resolution photoelectron imaging.4 The first observation of mode-specific auotodetachment of DBS of cold phenoxide have shown that not only vibrational hot bands were completely suppressed, but also rotational profile was observed.5 The vibrational frequencies of the DBS were found to be the same as those of the neutral radical, suggesting that vibrational structures of dipolar radicals can be probed via DBS.5 More significantly, the DBS resonances allowed a number of vibrational modes with very weak Frank-Condon factors to be "lightened" up via vibrational autodetachment.5 Recently, our first high-resolution vibrational spectroscopy of the dehydrogenated uracil radical, with partial rotational resolution, via autodetachment from DBS of cold deprotonated uracil anions have been reported.6 Rich vibrational information is obtained for this important radical species. The resolved rotational profiles also allow us to characterize the rotational temperature of the trapped anions for the first time.6 1 K. R. Lykke, D. M. Neumark, T. Andersen, V. J. Trapa, and W. C. Lineberger, J. Chem. Phys. 87, 6842 (1987). 2 D. M. Wetzel, and J. I. Brauman, J. Chem. Phys. 90, 68 (1989). 3 P. D. Dau, H. T. Liu, D. L. Huang, and L. S. Wang, J. Chem. Phys

  9. Cold Atom Physics Using Ultra-Thin Optical Fibers: Light-Induced Dipole Forces and Surface Interactions

    CERN Document Server

    Sagu'e, G; Meschede, D; Rauschenbeutel, A; Vetsch, E

    2007-01-01

    The strong evanescent field around ultra-thin unclad optical fibers bears a high potential for detecting, trapping, and manipulating cold atoms. Introducing such a fiber into a cold atom cloud, we investigate the interaction of a small number of cold Caesium atoms with the guided fiber mode and with the fiber surface. Using high resolution spectroscopy, we observe and analyze light-induced dipole forces, van der Waals interaction, and a significant enhancement of the spontaneous emission rate of the atoms. The latter can be assigned to the modification of the vacuum modes by the fiber.

  10. Design and test of the benches for the magnetic measurement of the LHC dipoles. [Large Hadron Collider

    Energy Technology Data Exchange (ETDEWEB)

    Billan, J.; Buckley, J.; Saban, R.; Sievers, P.; Walckiers, L. (CERN, Geneva (Switzerland))

    1994-07-01

    The magnetic measurement of more than 1,300 LHC dipoles comprises the content of higher harmonic field components, field direction and field integrals. The measurements will be carried out along a warm bore installed inside the magnet cold bore, thus allowing the use of rotating coils at room temperature. This coil, together with Hall and NMR detectors is mounted at one end of a 12.5 m long shaft which is specially designed for very high rotational stiffness and which is controlled from its far end by a motor, an angular encoder and a level meter, all standard components placed outside the magnetic field without space restrictions. Particular emphasis has been put on the user-friendliness of the bench and its automated, computer-controlled operation requiring a minimum of staff, an important issue during production measurements of large series of magnets. The bench and its performed and precision achieved during its commissioning are described.

  11. Correlation between magnetic field quality and mechanical components of the Large Hadron Collider main dipoles

    Energy Technology Data Exchange (ETDEWEB)

    Bellesia, B

    2006-12-15

    The 1234 superconducting dipoles of the Large Hadron Collider, working at a cryogenic temperature of 1.9 K, must guarantee a high quality magnetic field to steer the particles inside the beam pipe. Magnetic field measurements are a powerful way to detect assembly faults that could limit magnet performances. The aim of the thesis is the analysis of these measurements performed at room temperature during the production of the dipoles. In a large scale production the ideal situation is that all the magnets produced were identical. However all the components constituting a magnet are produced with certain tolerance and the assembly procedures are optimized during the production; due to these the reality drifts away from the ideal situation. We recollected geometrical data of the main components (superconducting cables, coil copper wedges and austenitic steel coil collars) and coupling them with adequate electro-magnetic models we reconstructed a multipolar field representation of the LHC dipoles defining their critical components and assembling procedures. This thesis is composed of 3 main parts: 1) influence of the geometry and of the assembling procedures of the dipoles on the quality of the magnetic field, 2) the use of measurement performed on the dipoles in the assembling step in order to solve production issues and to understand the behaviour of coils during the assembling step, and 3) a theoretical study of the uncertain harmonic components of the magnetic field in order to assess the dipole production.

  12. Magnetic relaxation and dipole-coupling-induced magnetization in nanostructured thin films during growth: A cluster Monte Carlo study

    Science.gov (United States)

    Brinzanik, R.; Jensen, P. J.; Bennemann, K. H.

    2003-11-01

    For growing inhomogeneous thin films with an island nanostructure similar to that observed in experiment we determine the nonequilibrium and the equilibrium remanent magnetization. The single-island magnetic anisotropy, the dipole coupling, and the exchange interaction between magnetic islands are taken into account within a micromagnetic model. A cluster Monte Carlo method is developed which includes coherent magnetization changes of connected islands. This causes a fast relaxation towards equilibrium for irregularly connected systems. We analyze the transition from dipole coupled islands at low coverages to a strongly connected ferromagnetic film at high coverages during film growth. For coverages below the percolation threshold the dipole interaction induces a collective magnetic order with ordering temperatures of 1 10 K for the assumed model parameters. Anisotropy causes blocking temperatures of 10 100 K and thus pronounced nonequilibrium effects. The dipole coupling leads to a somewhat slower magnetic relaxation.

  13. Dissecting an LHC dipole

    CERN Multimedia

    2004-01-01

    The cold mass of a 15-metre main dipole magnet has some fifteen different components. All the main components are manufactured under CERN's direct responsibility. Four of them transit through CERN before being shipped to the dipole assembly contractors, namely the cable, which constitutes the magnet's superconducting core (see Bulletin 14/2004), the beam screens, the heat exchanger tubes and the cold bore beam tubes. The two latter components transit via Building 927 where they undergo part of the production process. The 58-mm diameter heat exchanger tubes will remove heat from the magnets using superfluid helium. The 53-mm diameter cold bore tubes will be placed under vacuum to allow the twin beams to circulate around the LHC.

  14. Reversals of the solar magnetic dipole in the light of observational data and simple dynamo models

    CERN Document Server

    Moss, D; Sokoloff, D D; Hoeksema, J T

    2013-01-01

    Observations show that the photospheric solar magnetic dipole usually does not vanish during the inversion of the solar magnetic field, which occurs in each solar cycle. In contrast, mean-field solar dynamo models predict that the dipole field does become zero. In a recent paper Moss et al. (2013) suggested that this contradiction can be explained as a large-scale manifestation of small-scale magnetic fluctuations. Our aim is to confront this interpretation with the available observational data. Here we compare this interpretation with WSO (Wilcox Solar Observatory) photospheric magnetic field data in order to determine the amplitude of magnetic fluctuations required to explain the phenomenon and to compare the results with predictions from a simple dynamo model which takes fluctuations into account. We demonstrate that the WSO data concerning the magnetic dipole inversions are very similar indeed to the predictions of our very simple solar dynamo model, which includes both mean magnetic field and fluctuation...

  15. Revised spin down of SGR 0418+5729: a no longer so low dipole magnetic field?

    CERN Document Server

    Tong, H

    2012-01-01

    The spin down behaviors of SGR 0418+5729 are investigated. The pulsar spin down model of Contopoulos & Spitkovsky (2006) is applied to SGR 0418+5729. It is shown that SGR 0418+5729 lies below the pulsar death line and its rotation-powered magnetospheric activities may therefore have stopped. The compact star is now spun down by the magnetic dipole moment perpendicular to its rotation axis. Our calculations show that SGR 0418+5729 may be a low magnetic field magnetar. However, it may also have a strong dipole magnetic field, if there is a small magnetic inclination angle. This result is obtained under the general assumption that its braking mechanism is similar to that of rotation-powered pulsars. Its dipole magnetic field may be much higher than the characteristic magnetic field. Therefore, SGR 0418+5729 may be a normal magnetar instead of a low magnetic field magnetar.

  16. Zero-quantum frequency-selective recoupling of homonuclear dipole-dipole interactions in solid state nuclear magnetic resonance.

    Science.gov (United States)

    Hu, Kan-Nian; Tycko, Robert

    2009-07-28

    We describe a method for measuring magnetic dipole-dipole interactions, and hence distances, between pairs of like nuclear spins in a many-spin system under magic-angle spinning (MAS). This method employs a homonuclear dipolar recoupling sequence that creates an average dipole-dipole coupling Hamiltonian under MAS with full zero-quantum symmetry, including both secular and flip-flop terms. Flip-flop terms are then attenuated by inserting rotor-synchronized periods of chemical shift evolution between recoupling blocks, leaving an effective Hamiltonian that contains only secular terms to a good approximation. Couplings between specific pairs of nuclear spins can then be selected with frequency-selective pi pulses. We demonstrate this technique, which we call zero-quantum shift evolution assisted homonuclear recoupling, in a series of one-dimensional and two-dimensional (13)C NMR experiments at 17.6 T and 40.00 kHz MAS frequency on uniformly (13)C-labeled L-threonine powder and on the helix-forming peptide MB(i+4)EK, synthesized with a pair of uniformly (13)C-labeled L-alanine residues. Experimental demonstrations include measurements of distances between (13)C sites that are separated by three bonds, placing quantitative constraints on both sidechain and backbone torsion angles in polypeptides.

  17. Control of lattice spacing in a triangular lattice of feeble magnetic particles formed by induced magnetic dipole interactions

    Directory of Open Access Journals (Sweden)

    Noriyuki Hirota, Tsutomu Ando, Ryo Tanaka, Hitoshi Wada and Yoshio Sakka

    2009-01-01

    Full Text Available We studied methods of controlling the spacing between particles in the triangular lattice formed by feeble magnetic particles through induced magnetic dipole interaction. Formation of a triangular lattice is described by the balance between the magnetic force and the interaction of induced magnetic dipoles. The intensity of the magnetic force is proportional to the volume of particles V and the difference in the magnetic susceptibilities between the particles and the surrounding medium Δχ. On the other hand, the intensity of the induced magnetic dipole interaction depends on the square of V and Δχ. Therefore, altering the magnetic susceptibility difference by changing the susceptibility of the surrounding medium, volume of the particles, and intensity and spatial distribution of the applied magnetic field effectively controls the distance between the particles. In this study, these three methods were evaluated through experiment and molecular dynamics simulations. The distance between the particles, i.e. the lattice constant of the triangular lattice, was varied from 1.7 to 4.0 in units of the particle diameter. Formation of self-organized triangular lattice through the induced magnetic dipole interaction is based on magnetism, a physical property that all materials have. Therefore, this phenomenon is applicable to any materials of any size. Consequently, structure formation through induced magnetic dipole interaction is a potential way of fabricating materials with ordered structures.

  18. Classical electrodynamics in material media and relativistic transformation of magnetic dipole moment

    Science.gov (United States)

    Kholmetskii, A. L.; Missevitch, O. V.; Yarman, T.

    2016-09-01

    We consider the relativistic transformation of the magnetic dipole moment and disclose its physical meaning, shedding light on the related difficulties in the physical interpretation of classical electrodynamics in material media.

  19. Localization technique research of a pipeline robot based on the magnetic-dipole model

    Institute of Scientific and Technical Information of China (English)

    Junyuan LI; Hongjun CHEN; Shengfeng LI; Xiaohua ZHANG

    2008-01-01

    The magnetic field distribution of an emission antenna is studied in this paper. When the slenderness ratio of the emission antenna is high, the emission antenna can be simplified as a magnetic dipole for practical application. The numerical results of the magnetic dipole magnetic field show that the magnetic magnitude dis-tribution has a hump-shape, whose direction is perpendi-cular with the antenna axis direction. A localization method based on the hump-shape signal detection is presented. The experimental result shows that the preci-sion can reach a value of + 5 cm. The method can be used to localize a pipeline robot working in a metal pipe.

  20. Design and Measurement of Dipole Magnets for CSNS 1.6GeV RCS

    CERN Document Server

    Li, Qing; Kang, Wen; Deng, Chang-dong; Chen, Wan

    2016-01-01

    The Rapid Cycling Synchrotron (RCS) in Chinese Spallation Neutron Source (CSNS) accelerates proton beam from 80Mev to 1.6GeV at a repetition rate of 25Hz. All dipole magnets of RCS are operated at AC with biased DC. Aiming at the properties of these dipole magnets, we take some methods to improve magnetic field quality in the good region and reduce eddy currents in the iron core . In this paper, we would present the process of the magnet design and temperature rise calculation. At the same time, the field measurement results and temperature test of the prototype magnet are also described and discussed.

  1. Enhanced second-harmonic generation driven from magnetic dipole resonance in AlGaAs nanoantennas

    Science.gov (United States)

    Carletti, Luca; Rocco, Davide; Locatelli, Andrea; Gili, Valerio; Leo, Giuseppe; De Angelis, Costantino

    2016-04-01

    We model the linear and nonlinear optical response of disk-shaped AlGaAs nanoantennas. We design nanoantennas with a magnetic dipole resonant mode in the near-infrared wavelength range, and we analyze volume second-harmonic generation driven by a magnetic dipole resonance by predicting a conversion efficiency exceeding 10-3 with 1 GW/cm2 of pump intensity.

  2. Effect of metallic and hyperbolic metamaterial surfaces on electric and magnetic dipole emission transitions

    DEFF Research Database (Denmark)

    Ni, X.; Naik, G. V.; Kildishev, A. V.

    2011-01-01

    Spontaneous emission patterns of electric and magnetic dipoles on different metallic surfaces and a hyperbolic metamaterial (HMM) surface were simulated using the dyadic Green’s function technique. The theoretical approach was verified by experimental results obtained by measuring angular......-dependent emission spectra of europium ions on top of different films. The results show the modified behavior of electric and magnetic dipoles on metallic and HMM surfaces. The results of numerical calculations agree well with experimental data....

  3. Effects of MHD slow shocks propagating along magnetic flux tubes in a dipole magnetic field

    Directory of Open Access Journals (Sweden)

    N. V. Erkaev

    2002-01-01

    Full Text Available Variations of the plasma pressure in a magnetic flux tube can produce MHD waves evolving into shocks. In the case of a low plasma beta, plasma pressure pulses in the magnetic flux tube generate MHD slow shocks propagating along the tube. For converging magnetic field lines, such as in a dipole magnetic field, the cross section of the magnetic flux tube decreases enormously with increasing magnetic field strength. In such a case, the propagation of MHD waves along magnetic flux tubes is rather different from that in the case of uniform magnetic fields. In this paper, the propagation of MHD slow shocks is studied numerically using the ideal MHD equations in an approximation suitable for a thin magnetic flux tube with a low plasma beta. The results obtained in the numerical study show that the jumps in the plasma parameters at the MHD slow shock increase greatly while the shock is propagating in the narrowing magnetic flux tube. The results are applied to the case of the interaction between Jupiter and its satellite Io, the latter being considered as a source of plasma pressure pulses.

  4. Gyre-driven decay of the Earth’s magnetic dipole

    DEFF Research Database (Denmark)

    Finlay, Christopher C.; Aubert, Julien; Gillet, Nicolas

    2016-01-01

    Direct observations indicate that the magnitude of the Earth’s magnetic axial dipole has decreased over the past 175 years; it is now 9% weaker than it was in 1840. Here we show how the rate of dipole decay may be controlled by a planetary-scale gyre in the liquid metal outer core. The gyre......’s meridional limbs on average transport normal polarity magnetic flux equatorward and reverse polarity flux poleward. Asymmetry in the geomagnetic field, due to the South Atlantic Anomaly, is essential to the proposed mechanism. We find that meridional flux advection accounts for the majority of the dipole...... decay since 1840, especially during times of rapid decline, with magnetic diffusion making an almost steady contribution generally of smaller magnitude. Based on the morphology of the present field, and the persistent nature of the gyre, the current episode of dipole decay looks set to continue...

  5. Purely electric and magnetic dipole resonances in metamaterial dielectric resonators through perturbation theory inspired geometries

    CERN Document Server

    Campione, Salvatore; Warne, Larry K; Sinclair, Michael B

    2014-01-01

    In this paper we describe a methodology for tailoring the design of metamaterial dielectric resonators, which represent a promising path toward low-loss metamaterials at optical frequencies. We first describe a procedure to decompose the far field scattered by subwavelength resonators in terms of multipolar field components, providing explicit expressions for the multipolar far fields. We apply this formulation to confirm that an isolated high-permittivity cube resonator possesses frequency separated electric and magnetic dipole resonances, as well as a magnetic quadrupole resonance in close proximity to the electric dipole resonance. We then introduce multiple dielectric gaps to the resonator geometry in a manner suggested by perturbation theory, and demonstrate the ability to overlap the electric and magnetic dipole resonances, thereby enabling directional scattering by satisfying the first Kerker condition. We further demonstrate the ability to push the quadrupole resonance away from the degenerate dipole ...

  6. Demonstration of Magnetic Dipole Resonances of Dielectric Nanospheres in the Visible Region

    DEFF Research Database (Denmark)

    Evlyukhin, A. B.; Novikov, S. M.; Zywietz, U.

    2012-01-01

    dipole excitation. Due to high permittivity, the magnetic dipole resonance is observed in the visible spectral range for Si nanoparticles with diameters of similar to 200 nm, thereby opening a way to the realization of isotropic optical metamaterials with strong magnetic responses in the visible region.......Strong resonant light scattering by individual spherical Si nanoparticles is experimentally demonstrated, revealing pronounced resonances associated with the excitation of magnetic and electric modes in these nanoparticles. It is shown that the low-frequency resonance corresponds to the magnetic...

  7. Compensation of the magnetization current induced sextupole error at LHC injection field by short lumped permanent sextupole magnets, incorporated into the end configuration of superconducting dipoles

    CERN Document Server

    Asner, A

    1985-01-01

    Compensation of the magnetization current induced sextupole error at LHC injection field by short lumped permanent sextupole magnets, incorporated into the end configuration of superconducting dipoles

  8. Magnetic Trapping of Cold Methyl Radicals

    CERN Document Server

    Liu, Yang; Djuricanin, Pavle; Zhou, Sida; Zhong, Wei; Mittertreiner, Tony; Carty, David; Momose, Takamasa

    2016-01-01

    We have demonstrated that a supersonic beam of methyl radicals (CH3) in the ground rotational state of both para and ortho species has been slowed down to a standstill with a magnetic molecular decelerator, and successfully captured spatially in an anti-Helmholtz magnetic trap for > 1 s. The translational temperature of the trapped CH3 radicals was about 200 mK. The methyl radical is a non-polar polyatomic molecule, which is predicted to be an ideal system for further cooling below 1 mK via sympathetic cooling with ultracold atoms. In addition, it is a highly reactive intermediate that plays an important role in various processes in cold environments such as planetary atmospheres and the interstellar medium. The demonstrated trapping capability of methyl radicals opens up various possibilities for realizing ultracold ensembles of molecules towards Bose-Einstein condensation of polyatomic molecules and investigations of reactions governed by quantum statistics.

  9. Magnetic Trapping of Cold Methyl Radicals

    Science.gov (United States)

    Liu, Yang; Vashishta, Manish; Djuricanin, Pavle; Zhou, Sida; Zhong, Wei; Mittertreiner, Tony; Carty, David; Momose, Takamasa

    2017-03-01

    We have demonstrated that a supersonic beam of methyl radicals (CH3 ) in the ground rotational state of both para and ortho species has been slowed down to standstill with a magnetic molecular decelerator, and successfully captured spatially in an anti-Helmholtz magnetic trap for >1 s . The trapped CH3 radicals have a mean translational temperature of about 200 mK with an estimated density of >5.0 ×1 07 cm-3 . The methyl radical is an ideal system for the study of cold molecules not only because of its high reactivities at low temperatures, but also because further cooling below 1 mK is plausible via sympathetic cooling with ultracold atoms. The demonstrated trapping capability of methyl radicals opens up various possibilities for realizing ultracold ensembles of molecules towards Bose-Einstein condensation of polyatomic molecules and investigations of reactions governed by quantum statistics.

  10. High uniformity magnetic coil for search of neutron electric dipole moment

    Energy Technology Data Exchange (ETDEWEB)

    Perez Galvan, A., E-mail: apg@caltech.edu [W.K. Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, CA, 91125 (United States); Plaster, B. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY, 40506 (United States); Boissevain, J.; Carr, R.; Filippone, B.W.; Mendenhall, M.P.; Schmid, R. [W.K. Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, CA, 91125 (United States); Alarcon, R.; Balascuta, S. [Department of Physics, Arizona State University, Tempe, AZ 85287 (United States)

    2011-12-21

    We present in this article a prototype magnetic coil that has been developed for a new search for the electric dipole moment of the neutron at the Spallation Neutron Source at Oak Ridge National Laboratory. The gradients of the magnetic field generated by the coil have been optimized to reduce known systematic effects and to yield long polarization lifetimes of the trapped particles sampling the highly uniform magnetic field. Measurements of the field uniformity of this prototype magnetic coil are also presented.

  11. Comparison of electric dipole and magnetic loop antennas for exciting whistler modes

    Science.gov (United States)

    Stenzel, R. L.; Urrutia, J. M.

    2016-08-01

    The excitation of low frequency whistler modes from different antennas has been investigated experimentally in a large laboratory plasma. One antenna consists of a linear electric dipole oriented across the uniform ambient magnetic field B0. The other antenna is an elongated loop with dipole moment parallel to B0. Both antennas are driven by the same rf generator which produces a rf burst well below the electron cyclotron frequency. The antenna currents as well as the wave magnetic fields from each antenna are measured. Both the antenna currents and the wave fields of the loop antenna exceed that of the electric dipole by two orders of magnitude. The conclusion is that loop antennas are far superior to dipole antennas for exciting large amplitude whistler modes, a result important for active wave experiments in space plasmas.

  12. Implementation of an offset-dipole magnetic field in a pulsar modelling code

    CERN Document Server

    Breed, M; Harding, A K; Johnson, T J

    2014-01-01

    The light curves of gamma-ray pulsars detected by the Fermi Large Area Telescope show great variety in profile shape and position relative to their radio profiles. Such diversity hints at distinct underlying magnetospheric and/or emission geometries for the individual pulsars. We implemented an offset-dipole magnetic field in an existing geometric pulsar modelling code which already includes static and retarded vacuum dipole fields. In our model, this offset is characterised by a parameter epsilon (with epsilon = 0 corresponding to the static dipole case). We constructed sky maps and light curves for several pulsar parameters and magnetic fields, studying the effect of an offset dipole on the resulting light curves. A standard two-pole caustic emission geometry was used. As an application, we compared our model light curves with Fermi data for the bright Vela pulsar.

  13. Ground State and Collective Modes of Magnetic Dipoles Fixed on Two-Dimensional Lattice Sites

    Science.gov (United States)

    Feldmann, John; Kalman, Gabor; Hartmann, Peter; Rosenberg, Marlene

    2006-10-01

    In complex (dusty) plasmas the grains may be endowed with intrinsic dipole moments. We present here our results of theoretical calculations accompanied by and Molecular Dynamics simulation findings on the ground state configuration and on the collective modes mode spectrum of a system of magnetic dipoles, interacting via the magnetic dipole pair-dipole potential, fixed on two-dimensional (2D) lattice sites. In particular, we We study a family of lattices that can be characterized by two parameters: (parallelogram)---the aspect ratio, c/a, and the rhombic angle, phi. The The new collective modes of in the system associated with the dipole-dipole interaction are the angular oscillations (or wobbling) of the direction of the dipoles about their equilibrium configurations. We identify in-plane and out-of-plane modes and display their dispersions. Orders of magnitudes of the parameters of the system relevant to possible future experiments will be discussed. JD Feldmann, G J Kalman and M Rosenberg, J. Phys. A: Math. Gen. 39 (2006) 4549-4553

  14. Performance of the LHC Final Prototype and First Pre-series Superconducting Dipole Magnets

    CERN Document Server

    Bottura, L; Gateau, M; Legrand, P; Modena, M; Naoui, K; Perini, D; Pugnat, P; Sanfilippo, S; Savary, F; Scandale, Walter; Siemko, A; Sievers, P; Spigo, G; Vlogaert, J; Wyss, C

    2002-01-01

    Within the LHC cryo-dipole program, six full-scale superconducting prototypes of final design were built in collaboration between Industry and CERN, followed by launching the manufacture of pre-series magnets. Five prototypes and the first of the pre-series magnets were tested at CERN. This paper reviews the main features and the performance of the cryo-dipoles tested at 4.2 K and 1.8 K. The results of the quench training, conductor performance, magnet protection, sensitivity to ramp rate and field characteristics are presented and discussed in terms of the design parameters.

  15. Pseudospin Symmetry and Forbidden Magnetic Dipole and Gamow-Teller Transitions

    Science.gov (United States)

    Ginocchio, Joseph

    1999-10-01

    Recently it has been shown that pseudospin symmetry has its origins in a relativistic symmetry of the Dirac Hamiltonian[1]. Using this symmetry we relate single - nucleon relativistic magnetic moments of states in a pseudospin doublet to the relativistic magnetic dipole transitions between the states in the doublet, and we relate single - nucleon relativistic Gamow - Teller transitions within states in the doublet. We apply these relationships to the Gamow - Teller transitions from ^39Ca to its mirror nucleus ^39K [2] and to the systematics of forbidden magnetic dipole transitions. 1. J. N. Ginocchio and A. Leviatan Phys. Lett. B 425, 1 (1998). 2. J. N. Ginocchio Phys. Rev. C 59, 2487 (1999).

  16. A first dipole magnet was delivered to its final location in the LHC tunnel (1)

    CERN Multimedia

    2005-01-01

    On 7 March at 2.00 p.m., the first 35-tonne dipole magnet was lowered down through the PMI2 shaft, reaching the floor of the TI2 transfer tunnel thirty minutes later. The magnet was transported to its final location between Points 8 and 1 by a specially designed vehicle.

  17. An Experimental 11.5 T Nb3Sn LHC Type of Dipole Magnet

    NARCIS (Netherlands)

    Ouden, den A.; Wessel, S.; Krooshoop, E.; Dubbeldam, R.; Kate, ten H.H.J.

    1994-01-01

    As part of the magnet development program for the LHC an experimental 1 m long 11.5 T single aperture Nb3Sn dipole magnet has been designed and is now under construction. The design is focused on full utilisation of the high current density in the powder tube Nb3Sn. A new field optimisation has led

  18. Experimental investigation of axial plasma injection into a magnetic dipole field

    DEFF Research Database (Denmark)

    Jensen, Vagn Orla

    1968-01-01

    A high-density helium plasma, accelerated from a conical pinch, is injected axially into a magnetic dipole field. Magnetic probe measurements show that, near the axis, a compression of the field is super-imposed on the standard diamagnetic depression. The compression starts downstream and moves...

  19. A prototype vector magnetic field monitoring system for a neutron electric dipole moment experiment

    CERN Document Server

    Nouri, N; Brown, M A; Carr, R; Filippone, B; Osthelder, C; Plaster, B; Slutsky, S; Swank, C

    2015-01-01

    We present results from a first demonstration of a magnetic field monitoring system for a neutron electric dipole moment experiment. The system is designed to reconstruct the vector components of the magnetic field in the interior measurement region solely from exterior measurements.

  20. Temperature dependence of magnetic moments of nanoparticles and their dipole interaction in magnetic fluids

    Energy Technology Data Exchange (ETDEWEB)

    Lebedev, A.V.

    2015-01-15

    Magnetic susceptibility measurements were carried out for magnetite-based fluids over a wide temperature range. The fluids were stabilized with commonly used surfactants (fatty acids) and new surfactants (polypropylene glycol and tallow acids). The coefficients of temperature dependence of the particle magnetic moments were determined by fitting of the measured and calculated values of magnetic susceptibility. The influence of the inter-particle dipole–dipole interaction on the susceptibility was taken into account in the framework of A.O. Ivanov's model. The corrections for thermal expansion were determined by density measurements of the carrier fluid. The obtained values of temperature coefficients correlate to the solidification temperature of the fluid samples. For fluids with a low solidification temperature the value of the temperature coefficient of particle magnetization coincides with its value for bulk magnetite. - Highlights: • Susceptibility measurements made for magnetic fluids over a wide temperature range. • Temperature coefficients of particle magnetization found from susceptibility data. • The value of coefficients correlates to the solidification temperature of the fluid. • For the lowest solidification temperature the coefficient corresponds to that of bulk magnetite.

  1. Braking index of isolated pulsars. II. A novel two-dipole model of pulsar magnetism

    Science.gov (United States)

    Hamil, O.; Stone, N. J.; Stone, J. R.

    2016-09-01

    The magnetic dipole radiation model is currently the best approach we have to explain pulsar radiation. However, a most characteristic parameter of the observed radiation, the braking index nobs , shows deviations for all the eight best studied isolated pulsars, from the simple model prediction ndip=3 . The index depends upon the rotational frequency and its first and second time derivatives but also on the assumption that the magnetic dipole moment and inclination angle and the moment of inertia of the pulsar are constant in time. In a recent paper [Phys. Rev. D 91, 063007 (2015)], we showed conclusively that changes in the moment of inertia with frequency alone cannot explain the observed braking indices. Possible observational evidence for the magnetic dipole moment migrating away from the rotational axis at a rate α ˙ ˜0.6 ° per 100 years over the lifetime of the Crab pulsar has been recently suggested by Lyne et al. In this paper, we explore the magnetic dipole radiation model with constant moment of inertia and magnetic dipole moment but variable inclination angle α . We first discuss the effect of the variation of α on the observed braking indices and show they all can be understood. However, no explanation for the origin of the change in α is provided. After discussion of the possible source(s) of magnetism in pulsars, we propose a simple mechanism for the change in α based on a toy model in which the magnetic structure in pulsars consists of two interacting dipoles. We show that such a system can explain the Crab observation and the measured braking indices.

  2. 3-D Magnetic Sensor Module for Locating and Tracking MEMS Swallowable Capsule Based on Scalar Form of Magnetic Dipole Model

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    MEMS swallowable capsule is a novel technology in the non-invasive surgery. This technology provides a way to diagnose directly into the deep intestinal where the traditional invasive technology implemented, such as X-Ray, endoscopy. It is a key for us to locate and track the position of a MEMS capsule in clinical applications. To solve this problem, we implemented a magnetic sensor module based on the scalar form of the magnetic dipole model,which was designed with very small size (5.2 * 2.1 * 1.2 cm) and easy to assemble to satisfy the system requirement. Here we discuss in detail the principle of magnetic dipole model, rules of selecting sensor and functions of the module. Some trials are established to test the characteristic of the module. The results of the Cm experiment demonstrates that the module follows the rules of the new magnetic dipole model form.

  3. Magnetic anomaly inversion using magnetic dipole reconstruction based on the pipeline section segmentation method

    Science.gov (United States)

    Pan, Qi; Liu, De-Jun; Guo, Zhi-Yong; Fang, Hua-Feng; Feng, Mu-Qun

    2016-06-01

    In the model of a horizontal straight pipeline of finite length, the segmentation of the pipeline elements is a significant factor in the accuracy and rapidity of the forward modeling and inversion processes, but the existing pipeline segmentation method is very time-consuming. This paper proposes a section segmentation method to study the characteristics of pipeline magnetic anomalies—and the effect of model parameters on these magnetic anomalies—as a way to enhance computational performance and accelerate the convergence process of the inversion. Forward models using the piece segmentation method and section segmentation method based on magnetic dipole reconstruction (MDR) are established for comparison. The results show that the magnetic anomalies calculated by these two segmentation methods are almost the same regardless of different measuring heights and variations of the inclination and declination of the pipeline. In the optimized inversion procedure the results of the simulation data calculated by these two methods agree with the synthetic data from the original model, and the inversion accuracies of the burial depths of the two methods are approximately equal. The proposed method is more computationally efficient than the piece segmentation method—in other words, the section segmentation method can meet the requirements for precision in the detection of pipelines by magnetic anomalies and reduce the computation time of the whole process.

  4. Magnetic dipole moment of a spherical shell with TRM acquired in a field of internal origin. [Thermoremanent Magnetization implications for lunar magnetic field

    Science.gov (United States)

    Srnka, L. J.

    1976-01-01

    The acquisition of thermoremanent magnetization (TRM) by a cooling spherical shell is studied for internal magnetizing dipole fields, using Runcorn's (1975) theorems on magnetostatics. If the shell cools progressively inward, inner regions acquire TRM in a net field composed of the dipole source term plus a uniform field due to the outer magnetized layers. In this case, the global dipole moment and external remanent field are nonzero when the whole shell has cooled below the Curie point and the source dipole has disappeared. The remanent field outside the shell is found to depend on the thickness, radii, and cooling rate of the shell, as well as the coefficient of TRM and the intensity of the magnetizing field. Some implications for the moon's remanent dipole moment are discussed.

  5. POLARIZATION OF MAGNETIC DIPOLE EMISSION AND SPINNING DUST EMISSION FROM MAGNETIC NANOPARTICLES

    Energy Technology Data Exchange (ETDEWEB)

    Hoang, Thiem [Institute of Theoretical Physics, Goethe Universität Frankfurt, D-60438 Frankfurt am Main (Germany); Lazarian, Alex [Department of Astronomy, University of Wisconsin-Madison, Madison, WI 53705 (United States)

    2016-04-20

    Magnetic dipole emission (MDE) from interstellar magnetic nanoparticles is potentially an important Galactic foreground in the microwave frequencies, and its polarization level may pose great challenges for achieving reliable measurements of cosmic microwave background B-mode signal. To obtain realistic predictions for the polarization of MDE, we first compute the degree of alignment of big silicate grains incorporated with magnetic inclusions. We find that thermally rotating big grains with magnetic inclusions are weakly aligned and can achieve alignment saturation when the magnetic alignment rate becomes much faster than the rotational damping rate. We then compute the degree of alignment for free-flying magnetic nanoparticles, taking into account various interaction processes of grains with the ambient gas and radiation field, including neutral collisions, ion collisions, and infrared emission. We find that the rotational damping by infrared emission can significantly decrease the degree of alignment of small particles from the saturation level, whereas the excitation by ion collisions can enhance the alignment of ultrasmall particles. Using the computed degrees of alignment, we predict the polarization level of MDE from free-flying magnetic nanoparticles to be rather low. Such a polarization level is within the upper limits measured for anomalous microwave emission (AME), which indicates that MDE from free-flying iron particles may not be ruled out as a source of AME. We also quantify rotational emission from free-flying iron nanoparticles with permanent magnetic moments and find that its emissivity is about one order of magnitude lower than that from spinning polycyclic aromatic hydrocarbons.

  6. Electric Dipole Antennas With Magnetic-Coated PEC Cores: Reaching the Chu Lower Bound on Q

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.

    2012-01-01

    The radiation properties of spherical electric dipole antennas with electric current excitation and material-coated perfectly electrically conducting (PEC) cores are investigated analytically using vector spherical wave functions. Closed-form expressions for electric and magnetic stored energy as...... as well as the radiation quality factor $Q$ are derived. Using these, it is shown that properly selected magnetic coating and radius of the PEC core vastly reduce the internal stored energy, and thus make the $Q$ of an electric dipole antenna approach the Chu lower bound....

  7. Microwave probes Dipole Blockade and van der Waals Forces in a Cold Rydberg Gas

    CERN Document Server

    Teixeira, R Celistrino; Nguyen, Thanh Long; Cantat-Moltrecht, T; Raimond, Jean-Michel; Haroche, S; Gleyzes, S; Brune, M

    2015-01-01

    We show that microwave spectroscopy of a dense Rydberg gas trapped on a superconducting atom chip in the dipole blockade regime reveals directly the dipole-dipole many-body interaction energy spectrum. We use this method to investigate the expansion of the Rydberg cloud under the effect of repulsive van der Waals forces and the breakdown of the frozen gas approximation. This study opens a promising route for quantum simulation of many-body systems and quantum information transport in chains of strongly interacting Rydberg atoms.

  8. Design and cost estimation of the ASACUSA dipole magnets (PXMCXAFWAC)

    CERN Document Server

    Newborough, Antony

    2011-01-01

    This note describes the design and cost estimation for two horizontal bending magnets (PXMCXAFWAC) needed upstream of the ASACUSA experiment of the CERN AD (Antiproton Decelerator) Machine. These magnets are to replace the two corrector magnets (PXMCCAVWAP) which do not fulfil the requirements in terms of free horizontal aperture and field quality.

  9. Determination of AC Characteristics of Superconducting Dipole Magnets in the Large Hadron Collider Based on Experimental Results and Simulations

    CERN Document Server

    Ambjørndalen, Sara; Verweij, Arjan

    The Large Hadron Collider (LHC) utilizes high-field superconducting Main Dipole Magnets that bend the trajectory of the beam. The LHC ring is electrically divided into eight octants, each allocating a 7 km chain of 154 Main Dipole Magnets. Dedicated de- tection and protection systems prevent irreversible magnet damage caused by quenches. Quench is a local transition from the superconducting to the normal conducting state. Triggering of such systems, along with other failure scenarios, result in fast transient phenomena. In order to analyze the consequence of such electrical transients and failures in the dipole chain, one needs a circuit model that is validated against measurements. Currently, there exists an equivalent circuit of the Main Dipole Magnet resolved at an aperture level. Each aperture model takes into account the dynamic effects occurring in the magnets, trough a lossy-inductance model and parasitic capacitances to ground. At low frequencies the Main Dipole Magnet behaves as a linear inductor. Ca...

  10. Magnetic Dipole and Electric Quadrupole Transitions in the Trivalent Lanthanide Series: Calculated Emission Rates and Oscillator Strengths

    CERN Document Server

    Dodson, Christopher M

    2012-01-01

    Given growing interest in optical-frequency magnetic dipole transitions, we use intermediate coupling calculations to identify strong magnetic dipole emission lines that are well suited for experimental study. The energy levels for all trivalent lanthanide ions in the 4fn configuration are calculated using a detailed free ion Hamiltonian, including electrostatic and spin-orbit terms as well as two-body, three-body, spin-spin, spin-other-orbit, and electrostatically correlated spin-orbit interactions. These free ion energy levels and eigenstates are then used to calculate the oscillator strengths for all ground-state magnetic dipole absorption lines and the spontaneous emission rates for all magnetic dipole emission lines including transitions between excited states. A large number of strong magnetic dipole transitions are predicted throughout the visible and near-infrared spectrum, including many at longer wavelengths that would be ideal for experimental investigation of magnetic light-matter interactions wit...

  11. Laminar and transitional liquid metal duct flow near a magnetic point dipole

    CERN Document Server

    Tympel, Saskia; Schumacher, Jörg

    2013-01-01

    The flow transformation and the generation of vortex structures by a strong magnetic dipole field in a liquid metal duct flow is studied by means of three-dimensional direct numerical simulations. The dipole is considered as the paradigm for a magnetic obstacle which will deviate the streamlines due to Lorentz forces acting on the fluid elements. The duct is of square cross-section. The dipole is located above the top wall and is centered in spanwise direction. Our model uses the quasi-static approximation which is applicable in the limit of small magnetic Reynolds numbers. The analysis covers the stationary flow regime at small hydrodynamic Reynolds numbers $Re$ as well as the transitional time-dependent regime at higher values which may generate a turbulent flow in the wake of the magnetic obstacle. We present a systematic study of these two basic flow regimes and their dependence on $Re$ and on the Hartmann number $Ha$, a measure of the strength of the magnetic dipole field. Furthermore, three orientations...

  12. Design of the EuCARD High-Field Model Dipole Magnet FRESCA2

    CERN Document Server

    Milanese, A; Durante, M; Manil, P; Perez, J C; Rifflet, J M; de Rijk, G; Rondeaux, F

    2012-01-01

    This paper reports on the design of FRESCA2, a dipole magnet model wound with Nb3Sn Rutherford cable. This magnet is one of the deliverables of the High Field Magnets work package of the European FP7-EuCARD project. The nominal magnetic flux density of 13 Tesla in a 100 mm bore will make it suitable for upgrading the FRESCA cable test facility at CERN. The magnetic layout is based on a block coil, with four layers per pole. The mechanical structure is designed to provide adequate pre-stress, through the use of bladders, keys and an aluminum alloy shrinking cylinder.

  13. Van der Waals Interactions and Dipole Blockade in a Cold Rydberg Gas Probed by Microwave Spectroscopy

    Science.gov (United States)

    Nguyen, Thanh Long; Celistrino Teixeira, Raul; Hermann Avigliano, Carla; Cantat Moltrecht, Tigrane; Raimond, Jean Michel; Haroche, Serge; Gleyzes, Sebastiens; Brune, Michel

    2016-05-01

    Dipole-dipole interactions between Rydberg atoms are a flourishing tool for quantum information processing and for quantum simulation of complex many-body problems. Microwave spectroscopy of a dense Rydberg gas trapped close to a superconducting atom chip in the strong dipole blockade regime reveals directly the many-body atomic interaction spectrum. We present here a direct measurement of the interaction energy distribution in the strong dipole blockade regime, based on microwave spectroscopy. We first apply this method to the observation of the excitation dynamics of the Rydberg gas, conditioned by dipole-dipole interactions, in either the strong blockade regime or the so-called facilitation regime. We also observe with this method the atomic cloud expansion driven by the repulsive Van der Waals interaction after excitation. This measurement, in good agreement with Monte Carlo simulations of the excitation process and of the cloud dynamics, reveals the limits of the frozen gas approximation. This method can help investigate self-organization and dynamical phase transitions in Rydberg-atom based quantum simulators. This study thus opens a promising route for quantum simulation of many-body systems and quantum information transport in chains of strongly interacting Rydberg atom.

  14. Application of Laser Magnetic Resonance Spectroscopy to the Measurement of Electric Dipole Moment of Free Radicals

    Institute of Scientific and Technical Information of China (English)

    郭远清; 黄光明; 林洁丽; 段传喜; 李奉延; 李津蕊; 刘煜炎

    2001-01-01

    An intracavity CO laser magnetic resonance spectrometer with homogeneous dc electric field applied via a pairof parallel Stark plates in the absorption cell is used to measure the electric dipole moments of free radicals.Taking advantage of the high sensitivity and high resolution of this technique and the Stark effect, highlyresolved saturated absorption spectra of the ν = 1 - 0 transition of 15 N16 O in the ground state X2 П3/2 have beensuccessfully observed in the presence of a low electric field. The electric dipole moment of NO in the electronicground state is determined asμ = 0.1566 ± 14D (Debye) from the analysis of the observed spectra, confirmingthat, combined with the Stark field, the laser magnetic resonance technique can be an effective and reliableapproach for the precise measurement of electric dipole moments of free radicals, especially unstable ones.

  15. Magnetic dipole moment estimates for an ancient lunar dynamo

    Science.gov (United States)

    Anderson, K. A.

    1983-01-01

    The four measured planetary magnetic moments combined with a recent theoretical prediction for dynamo magnetic fields suggests that no dynamo exists in the moon's interior today. For the moon to have had a magnetic moment in the past of sufficient strength to account for at least some of the lunar rock magnetism, the rotation would have been about twenty times faster than it is today and the radius of the fluid, conducting core must have been about 750 km. The argument depends on the validity of the Busse solution to the validity of the MHD problem of planetary dynamos.

  16. LHC News : The 39th and final repaired dipole magnet was lowered into Sector 3-4 and installed

    CERN Multimedia

    CERN Multimedia Productions

    2009-01-01

    The 39th and final repaired dipole magnet was lowered into Sector 3-4 and installed on Thursday 16 April. This is the last of the LHC’s easily recognizable 15-metre-long blue superconducting dipoles required for the 3-4 repair. Interviews with Hervé Prin, Member of the LHC reconstruction team, Caterina Bertone, Magnet transport leader

  17. Electric and Magnetic Dipole States in ^238U

    Science.gov (United States)

    Hammond, S. L.; Adekola, A.; Angell, C. T.; Karwowski, H. J.; Howell, C. R.; Kwan, E.; Rusev, G.; Tonchev, A. P.; Tornow, W.; Kelley, J. H.

    2010-11-01

    An investigation of dipole states in ^238U is important for the fundamental understanding of its structure. Precise experimental information on the distribution of M1 and E1 transitions in ^238U has been obtained using the nuclear resonance fluorescence technique at the High-Intensity γ-ray Source at the Triangle Universities Nuclear Laboratory. Using 100% linearly-polarized, monoenergetic γ-ray beams between incident energies of 2.0 - 5.5 MeV, the spin, parity, width, and γ-strength of the ground-state deexcitations were determined. These measurements will form a unique data set that can be used for comparison with theoretical models of collective excitations in heavy, deformed nuclei. The data can also provide isotope-specific signatures to search for special nuclear materials.

  18. Conduction cooled high temperature superconducting dipole magnet for accelerator applications

    DEFF Research Database (Denmark)

    Zangenberg, N.; Nielsen, G.; Hauge, N.

    2012-01-01

    impregnated with epoxy and mounted between a support of stainless steel and a collar made from aluminum. The cold mass consisting of the coil assembly and a laminated steel yoke is cooled by two cryocoolers from via copper bars to below 20 K. Current leads were made from the same batch of HTS tape. Cryogen...... for accelerator applications in many fields, in particular where cryogenic liquid cooling is not an option....

  19. The role of magnetic dipoles and non-zero-order Bragg waves in metamaterial perfect absorbers.

    Science.gov (United States)

    Zeng, Yong; Chen, Hou-Tong; Dalvit, Diego A R

    2013-02-11

    We develop a simple treatment of a metamaterial perfect absorber (MPA) based on grating theory. We analytically prove that the condition of MPA requires the existence of two currents, which are nearly out of phase and have almost identical amplitude, akin to a magnetic dipole. Furthermore, we show that non-zero-order Bragg modes within the MPA may consume electromagnetic energy significantly.

  20. Gauge Invariance of a Time-Dependent Harmonic Oscillator in Magnetic Dipole Approximation

    Institute of Scientific and Technical Information of China (English)

    WANG Fei; QIAN Shang-Wu; FU Li-Ping; WANG Jing-Shan; GUO Ke-Tao

    2008-01-01

    A manifestly gauge-invariant formulation of non-relativistic quantum mechanics is applied to the case of time-dependent harmonic oscillator in the magnetic dipole approximation. A genera/ equation for obtaining gauge-invariant transition probability amplitudes is derived.

  1. Measurement of the electric dipole moment and magnetic moment anomaly of the muon

    NARCIS (Netherlands)

    Onderwater, CJG

    2005-01-01

    The experimental precision of the anomalous magnetic moment of the muon has been improved to 0.5 part-per-million by the Brookhaven E821 experiment, similar to the theoretical uncertainty. In the same experiment, a new limit on the electric dipole moment of 2.8 x 10(-19) e-cm (95% CL) was set. The e

  2. Progress in the development of an 88-mm bore 10 Tn3Sn dipole magnet

    NARCIS (Netherlands)

    Ouden, den A.; Wessel, W.A.J.; Kirby, G.A.; Taylor, T.; Siegel, N.; Kate, ten H.H.J.

    2001-01-01

    A 10 T, 2-layer cos(&thetas;)-dipole model magnet with an 88 mm clear bore utilizing an advanced powder-in-tube Nb3Sn conductor is being developed for the LHC. A dedicated conductor development program has resulted in a well performing Rutherford cable containing strands that uniquely exhibit both a

  3. Lower Bound for the Radiation $Q$ of Electrically Small Magnetic Dipole Antennas With Solid Magnetodielectric Core

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Breinbjerg, Olav

    2011-01-01

    A new lower bound for the radiation $Q$ of electrically small spherical magnetic dipole antennas with solid magnetodielectric core is derived in closed form using the exact theory. The new bound approaches the Chu lower bound from above as the antenna electrical size decreases. For $ka, the new...

  4. Investigation of the Periodic Magnetic Field Modulation in LHC Superconducting Dipoles

    CERN Document Server

    Pugnat, P; Siemko, A

    2002-01-01

    The windings of high-field accelerator magnets are usually made of Rutherford-type superconducting cables. The magnetic field distribution along the axis of such magnets exhibits a periodic modulation with a wavelength equal to the twist pitch length of the cable used in the winding. This effect, resulting from quasi-persistent currents, was investigated with a Hall probes array inserted inside the aperture of the LHC superconducting dipoles, both in short models and full-scale prototypes. The amplitude and the time dependence of this periodic field oscillation have been studied as a function of the magnet current history. The origin and the impact on the LHC dipoles stability of the non-uniform current redistribution producing such a field modulation are discussed.

  5. Quench calculations for the superconducting dipole magnet of CBM experiment at FAIR

    Science.gov (United States)

    Kurilkin, P.; Akishin, P.; Bychkov, A.; Floch, E.; Gusakov, Yu.; Ladygin, V.; Malakhov, A.; Moritz, G.; Ramakers, H.; Senger, P.; Shabunov, A.; Szwangruber, P.; Toral, F.

    2016-08-01

    The scientific mission of the Compressed Baryonic Matter (CBM) experiment is the study of the nuclear matter properties at the high baryon densities in heavy ion collisions at the Facility of Antiproton and Ion Research (FAIR) in Darmstadt. The 5.15 MJ superconducting dipole magnet will be used in the silicon tracking system of the CBM detector. It will provide a magnetic field integral of 1 Tm which is required to obtain a momentum resolution of 1% for the track reconstruction. This paper presents quench modeling and evaluation of candidate protection schemes for the CBM dipole magnet. Two quench programs based on finite-difference method were used in simulation. One of them is currently used at GSI, and the other based on CIEMAT (Madrid, Spain) was modified to perform quench calculation for the CBM magnet.

  6. Magnetic dipole radiation tailored by substrates: numerical investigation

    CERN Document Server

    Markovich, Dmitry L; Samusev, Anton; Belov, Pavel A; Zayats, Anatoly V

    2014-01-01

    Nanoparticles of high refractive index materials can possess strong magnetic polarizabilities and give rise to artificial magnetism in the optical spectral range. While the response of individual dielectric or metal spherical particles can be described analytically via multipole decomposition in the Mie series, the influence of substrates, in many cases present in experimental observations, requires different approaches. Here, the comprehensive numerical studies of the influence of a substrate on the spectral response of high- index dielectric nanoparticles were performed. In particular, glass, perfect electric conductor, gold, and hyperbolic metamaterial substrates were investigated. Optical properties of nanoparticles were characterized via scattering cross-section spectra, electric field profiles, and induced electric and magnetic moments. The presence of substrates was shown to introduce significant impact on particle's magnetic resonances and resonant scattering cross-sections. Variation of substrate mat...

  7. Experimental modelling of the dipole magnet for the electron storage ring DELSY

    CERN Document Server

    Meshkov, I N; Syresin, E M

    2003-01-01

    In the Joint Institute for Nuclear Research (Dubna) the project of Dubna Electron Synchrotron (DELSY) with an electron energy of 1.2 GeV is developed. The electron storage ring in the DELSY project is planned to be created on the basis of magnetic elements, which were used earlier in the storage ring AmPS (NIKHEF, Amsterdam). The optics of the ring is necessary to be changed, its perimeter to be reduced approximately in one and a half time, the energy of electrons to be increased. The paper is devoted to the development of a modified dipole magnet of the storage ring. The preliminary estimation of geometry of the magnet pole is carried out by means of computer modelling using two- and three- dimensional codes of the magnetic field calculation SUPERFISH and RADIA. The experimental stand for the measurements of the dipole magnetic field is described. As the result of calculational and experimental modelling for the dipole magnet, the geometry of its poles was estimated, providing in the horizontal aperture +- 3...

  8. In-orbit offline estimation of the residual magnetic dipole biases of the POPSAT-HIP1 nanosatellite

    Science.gov (United States)

    Seriani, S.; Brama, Y. L.; Gallina, P.; Manzoni, G.

    2016-05-01

    The nanosatellite POPSAT-HIP1 is a Cubesat-class spacecraft launched on the 19th of June 2014 to test cold-gas based micro-thrusters; it is, as of April 2015, in a low Earth orbit at around 600 km of altitude and is equipped, notably, with a magnetometer. In order to increment the performance of the attitude control of nanosatellites like POPSAT, it is extremely useful to determine the main biases that act on the magnetometer while in orbit, for example those generated by the residual magnetic moment of the satellite itself and those originating from the transmitter. Thus, we present a methodology to perform an in-orbit offline estimation of the magnetometer bias caused by the residual magnetic moment of the satellite (we refer to this as the residual magnetic dipole bias, or RMDB). The method is based on a genetic algorithm coupled with a simplex algorithm, and provides the bias RMDB vector as output, requiring solely the magnetometer readings. This is exploited to compute the transmitter magnetic dipole bias (TMDB), by comparing the computed RMDB with the transmitter operating and idling. An experimental investigation is carried out by acquiring the magnetometer outputs in different phases of the spacecraft life (stabilized, maneuvering, free tumble). Results show remarkable accuracy with an RMDB orientation error between 3.6 ° and 6.2 ° , and a module error around 7 % . TMDB values show similar coherence values. Finally, we note some drawbacks of the methodologies, as well as some possible improvements, e.g. precise transmitter operations logging. In general, however, the methodology proves to be quite effective even with sparse and noisy data, and promises to be incisive in the improvement of attitude control systems.

  9. Magnetic moment and electric dipole moment of the {tau}-lepton

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez-Rodriguez, A [Facultad de Fisica, Universidad Autonoma de Zacatecas, Apartado Postal C-580, 98060 Zacatecas, Zacatecas (Mexico); Hernandez-Ruiz, M A [Facultad de Ciencias Quimicas, Universidad Autonoma de Zacatecas, Codigo Postal 98600 Zacatecas, Zacatecas (Mexico); Luis-Noriega, L N [Facultad de Fisica, Universidad Autonoma de Zacatecas, Apartado Postal C-580, 98060 Zacatecas, Zacatecas (Mexico)

    2006-05-15

    Limits on the anomalous magnetic moment and the electric dipole moment of the {tau} lepton are calculated through the reaction e{sup +}e{sup -} {yields} {tau}{sup +}{tau}{sup -} {gamma} at the Z{sub 1}-pole and in the framework of a left-right symmetric model. The results are based on the recent data reported by the L3 Collaboration at CERN LEP. Due to the stringent limit of the model mixing angle {phi}, the effect of this angle on the dipole moments is quite small.

  10. Quantum magnetism and counterflow supersolidity of up-down bosonic dipoles

    Energy Technology Data Exchange (ETDEWEB)

    Trefzger, C; Alloing, M; Dubin, F; Lewenstein, M [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona) (Spain); Menotti, C, E-mail: christian.trefzger@gmail.co [INO-CNR BEC Center and Dipartimento di Fisica, Universita di Trento, 38123 Povo (Italy)

    2010-09-15

    We study a gas of dipolar bosons confined in a two-dimensional optical lattice. Dipoles are considered to point freely in both up and down directions perpendicular to the lattice plane. This results in a nearest-neighbor repulsive (attractive) interaction for aligned (anti-aligned) dipoles. We find regions of parameters where the ground state of the system exhibits insulating phases with ferromagnetic or anti-ferromagnetic ordering, as well as with rational values of the average magnetization. Evidence for the existence of a novel counterflow supersolid quantum phase is also presented.

  11. Fabrication of the shell-type $Nb_{3}$ Sn dipole magnet at Fermilab

    CERN Document Server

    Chichili, D R; Andreev, N; Barzi, E; Caspi, S; Kashikhin, V V; Limon, P J; Scanlan, R M; Terechkine, Yu; Tompkins, J; Wake, M; Yadav, S; Yamada, R; Yarba, V A; Zlobin, A V

    2001-01-01

    A 43.5 mm aperture dipole magnet with a nominal field of 11 T is being fabricated at Fermilab. The design is based on a two-layer shell-type coil structure made of Rutherford-type Nb/sub 3/Sn cable with wind and react technology. The mechanical support structure consists of vertically split iron yoke locked by two aluminum clamps and a 8 mm thick stainless steel skin. This paper summarizes the fabrication details of the first dipole model and test results from a 2110 mm long mechanical model. (9 refs).

  12. Controllable Magnetic Focusing of Cold Atoms on a Chip

    Institute of Scientific and Technical Information of China (English)

    LIU Yang; YUN Min; YIN Jian-Ping

    2006-01-01

    @@ We propose a new lens scheme to focus cold atoms by using a controllable inhomogeneous magnetic field from a square current-carrying wire fabricated on a chip. The spatial distributions of the magnetic field are calculated, and the results show that the generated magnetic field is a two-dimensional (2D) quadrupole one and can be used to focus cold atoms or a cold atomic beam. The dynamic processes of cold atoms passing through our square wire layout and its focusing properties are studied by using Monte Carlo simulations. Our study shows that the atomic clouds can be focused effectively by our magnetic lens scheme, and the focal lengthof the atomic lens and its radius of focused spot can be continuously changed by adjusting the current in the wires.

  13. Calculation and optimization of stray fields of septum dipole magnets

    CERN Document Server

    Holmes, Andrew J T

    1976-01-01

    A theoretical treatment is described of the external stray field of C- shaped septum magnets, such as those designed for the beam extraction systems of the 400 GeV CERN Super Proton Synchrotron. A special conformal transformation of the magnetic plane yields analytic expressions for the four components of the stray field: the septum- shape field (due to the form of the septum conductor), the edge-effect field (due to the mechanical clearance between septum and yoke), the cooling-duct field (due to the presence of these ducts in the septum), and the magnetomotance field (caused by the ampere-turn losses in the yoke). These expressions can be computed by numerical iteration. The septum-shape field turns out to be opposite in sign to the other three, making possible a criterion which creates a minimal stray field for a given magnetic induction. Plots of calculated and measured stray fields are presented for four prototype septum magnets whose total induction is between 0.38 and 1.41 T. (3 refs).

  14. Polarity reversals and tilt of the Earth's magnetic dipole

    Science.gov (United States)

    Dolginov, A. Z.

    1993-01-01

    There is evidence that the terrestrial magnetic field is connected with the Earth's mantle: (1) there are magnetic anomalies that do not take part in the westward drift of the main field, but are fixed with respect to the mantle; (2) the geomagnetic pole position flips in a particular way by preferred meridional paths during a reversal; and (3) magnetic polarity reversals are correlated with the activations of geological processes. These facts may be explained if we take into account that a significant horizontal temperature gradient can exist in the top levels of the liquid core because of the different thermoconductivity of the different areas of the core-mantle boundary. These temperature inhomogeneities can penetrate the core because fluxes along the core boundary (the thermal wind) can be strongly suppressed by a small redistribution of the chemical composition in the top of the core. The nonparallel gradients of the temperature, density, and composition on the top of the core create a curled electric field that produces a current and a magnetic field. This seed-field can be amplified by motions in the core. The resulting field does not forget the seed-field distribution and in this way the field on the Earth surface (that can be created only in regions with high conductivity, i.e. in the core) is connected with the core-mantle boundary. Contrary to the usual approach to the dynamo problem, we will take into account that the seed field of thermoelectric origin is acting not only at some initial moment of time but permanently.

  15. Electric and Magnetic Dipole Coupling in Near-Infrared Split-Ring Metamaterial Arrays

    Science.gov (United States)

    Sersic, Ivana; Frimmer, Martin; Verhagen, Ewold; Koenderink, A. Femius

    2009-11-01

    We present experimental observations of strong electric and magnetic interactions between split ring resonators (SRRs) in metamaterials. We fabricated near-infrared planar metamaterials with different inter-SRR spacings along different directions. Our transmission measurements show blueshifts and redshifts of the magnetic resonance, depending on SRR orientation relative to the lattice. The shifts agree well with simultaneous magnetic and electric near-field dipole coupling. We also find large broadening of the resonance, accompanied by a decrease in effective cross section per SRR with increasing density due to superradiant scattering. Our data shed new light on Lorentz-Lorenz approaches to metamaterials.

  16. Mercury intrinsic magnetic field : Limits of the offset-dipole representation

    Science.gov (United States)

    Chanteur, Gérard M.; Modolo, Ronan; Richer, Emilie; Hess, Sébastien; Leblanc, François

    2013-04-01

    The interaction of the solar wind (SW) with the magnetic field of The analysis of MESSENGER orbital observations led Anderson et al (2011) to propose a dipole centered on the spin axis of the planet with a northward offset equal to 484±11 km to represent the intrinsic magnetic field of Mercury at northern latitudes higher than 30°. The magnetic moment has a magnitude of 195±10nT, points southward and is tilted by less than 3° with respect to the spin axis. The restriction to northern latitude comes from the lack of low altitude measurements of the magnetic field at southern latitudes due to MESSENGER orbit. Hence for the moment being there is no observation to constrain the representation of the southern planetary field. The suggested offset is equal to about 20% of the planetary radius which is quite a large value by comparison to 8.5% in the terrestrial case although with a lateral offset. This representation of the intrinsic field by an offset dipole suggests that the southern polar cap should be much wider than the northern one, leading to important consequences for magnetospheric dynamics. Nevertheless the offset dipole is just a convenient representation that can be fitted by the first terms of the multipolar development. The surface field of the planet produced by the offset dipole (OD) proposed by Anderson et al (2011) is thus fitted by the sum of a dipolar and a quadrupolar field (DQ) for northern latitudes higher than 50°. The resulting field differs slightly from the offset dipole field at northern latitudes but a separatrix exists at southern latitudes between dipolar-like and quadrupolar like field lines. This separatrix begins on the polar axis at an altitude RS equal to three times the ratio of the quadrupolar to the dipolar moment. When the relative axial offset of the dipole becomes larger than 16% then RS becomes larger than the planetary radius leading to important topological changes of the southern field. Global hybrid simulations of the

  17. Dual AC Dipole Excitation for the Measurement of Magnetic Multipole Strength from Beam Position Monitor Data

    Energy Technology Data Exchange (ETDEWEB)

    M. Spata, G.A. Krafft

    2011-09-01

    An experiment was conducted at Jefferson Lab's Continuous Electron Beam Accelerator Facility to develop a technique for characterizing the nonlinear fields of the beam transport system. Two air-core dipole magnets were simultaneously driven at two different frequencies to provide a time-dependent transverse modulation of the electron beam. Fourier decomposition of beam position monitor data was then used to measure the amplitude of these frequencies at different positions along the beamline. For a purely linear transport system one expects to find solely the frequencies that were applied to the dipoles with amplitudes that depend on the phase advance of the lattice. In the presence of nonlinear fields one expects to also find harmonics of the driving frequencies that depend on the order of the nonlinearity. The technique was calibrated using one of the sextupole magnets in a CEBAF beamline and then applied to a dipole to measure the sextupole and octupole strength of the magnet. A comparison is made between the beam-based measurements, results from TOSCA and data from our Magnet Measurement Facility.

  18. Design and Status of the Dipole Spectrometer Magnet for the ALICE Experiment

    CERN Document Server

    Bartenev, V D; Datskov, V I; Koshurnikov, E; Shabounov, A; Shishov, Yu A; Swoboda, Detlef; Vodopyanov, A S

    2000-01-01

    Proposal of abstract for MT16, Tallahesse, Florida, 26th September to 2nd October 1999.A large Dipole Magnet is required for the Muon Arm Spectrometer of the ALICE experiment at the LHC.The absence of strong requirements on the symmetry and homogeneity of the magnetic field has lead to a design dominated by economic and feasibility considerations.In March 1997 the decision was taken to build a resistive dipole magnet for the muon spectrometer of the ALICE experiment. Since then, design work has been pursued in JINR/Russia and at CERN. While a common concept has been adopted for the construction of the steel core, two different proposals have been made for the manufacturing technology of the excitation coils. In both cases, however, the conductor material will be Aluminium.The general concept of the dipole magnet is based on a window frame return yoke, fabricated from low carbon steel sheets. The flat vertical poles follow the defined acceptance angle of 9 degrees. The excitation coils are of saddle type. The ...

  19. A Magnetic Disturbance Compensation Method Based on Magnetic Dipole Magnetic Field Distributing Theory

    Institute of Scientific and Technical Information of China (English)

    YANG Yun-tao; SHI Zhi-yong; L(U) Jian-gang; GUAN Zhen-zhen

    2009-01-01

    The interference of carrier magnetic field to geomagnetic field has been a difficult problem for a long time, which influences on the deviation of navigation compass and the error of geomagnetic measurement. To increase the geomagnetic measuring accuracy required for the geomagnetic matching localization, the strategy to eliminate the effect of connatural and induced magnetic fields of carrier on the geomagnetic measuring accuracy is investigated. The magnetic-dipoles magnetic field distributing theory is used to deduce the magnetic composition in the position of the sensor installed on the carrier. A geomagnetic measurement model is established by using the measuring data with the ideal sensor. Considering the magnetic disturbance of carrier and the error of sensor, a geomagnetic measuring compensation model is built. This model can be used to compensate the errors of carrier magnetic field and magnetic sensor in any case and its parameters have clear or specific physical meaning. The experimented results show that the model has higher geomagnetic measuring accuracy than that of others.

  20. Static charged fluid around a massive magnetic dipole

    CERN Document Server

    Polanco, Jose D; Ujevic, Maximiliano

    2008-01-01

    An analytical solution of Einstein-Maxwell equations with a static fluid as a source is presented. The spacetime is represented by the axially symmetric Weyl metric and the energy-momentum tensor describes a coupling of a fluid with an electromagnetic field. When appropriate limits are performed we recover the well-known solutions of Gutsunaev-Manko and Schwarzschild. Also, using Eckart's thermodynamics, we calculated the temperature, the mechanical pressure, the charge density and the energy density of the system. The analysis of thermodynamic quantities suggests that the solution can be used to represent a magnetized compact stellar object surrounded by a charged fluid.

  1. A New Hermean Magnetic Field Model using a Modified Equivalent Source Dipole Method

    Science.gov (United States)

    Oliveira, Joana S.; Langlais, Benoit; Pais, M. Alexandra; Amit, Hagay; Thébault, Erwan

    2017-04-01

    Mercury is the only terrestrial planet, besides the Earth, that has a core dynamo which generates a global magnetic field. MESSENGER orbited Mercury from 2011 to 2015 and provided magnetic measurements which convey crucial information on the magnetic field environment of the planet. We use a local method based on Equivalent Source Dipole approach to model the internal field of Mercury. The method is especially well suited when measurements cover a limited fraction of the planet's surface. Dipoles are placed deep into the planet. Note that with this modeling scheme, we do not attempt to explicitly model the external field. As the planet is in spin-orbit resonance completing three sidereal days in two years, it takes three sidereal days (one solar day) for the Sun to cover all local longitudes. We therefore consider successive periods of one solar day. A dominantly axisymmetric field is found for each solar-day model showing a significant temporal variability. This could be due to some large-scale external field that appears as internal with respect to the spacecraft orbit. The changing altitude and latitude coverage of each model may also be invoked for this variability. We finally compute a 8-solar-day model, including all solar days during the MESSENGER mission, to describe the Hermean magnetic field. Maps of the field computed at 200 km altitude show a magnetic equator at 16°N latitude, and confirm the large-scale and close-to-axisymmetry structure of the internal magnetic field of Mercury. Our model is also in agreement with the magnetic equator crossings detected before. However, our magnetic equator latitude varies with the altitude to the planet. This is indicative that the dipole-offset hypothesis is over-simplified, and that dynamo modelers have to consider alternative models when attempting to model the Hermean dynamo.

  2. Data Analysis of Transient Energy Releases in the LHC Superconducting Dipole Magnets

    CERN Document Server

    Calvi, M; Bottura, L; Di Castro, M; Masi, A; Siemko, A

    2007-01-01

    Premature training quenches are caused by transient energy released within the LHC dipole magnet coils while it is energized. Voltage signals recorded across the magnet coils and on the so-called quench antenna carry information about these disturbances. The transitory events correlated to transient energy released are extracted making use of continuous wavelet transform. Several analyses are performed to understand their relevance to the so called training phenomenon. The statistical distribution of the signals amplitude, the number of events occurring at a given current level, the average frequency content of the events are the main parameters on which the analysis have been focalized. Comparisons among different regions of the magnet, among different quenches in the same magnet and among magnets made by different builders are reported. Conclusions about the efficiency of the raw data treatment and the relevance of the parameters developed with respect to the magnet global behavior are finally given.

  3. Prospects for searching axion-like particle dark matter with dipole, toroidal and wiggler magnets

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Oliver K. [Yale Univ., New Haven, CT (United States). Dept. of Physics; Betz, Michael; Caspers, Fritz [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Jaeckel, Joerg [Institute for Particle Physics Phenomenology, Durham (United Kingdom); Lindner, Axel; Ringwald, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Semertzidis, Yannis [Brookhaven National Lab., Upton, NY (United States); Sikivie, Pierre [Florida Univ., Gainesville, FL (United States). Dept. of Physics; Zioutas, Konstantin [Patras Univ. (Greece)

    2011-10-15

    In this work we consider searches for dark matter made of axions or axion-like particles (ALPs) using resonant radio frequency cavities inserted into dipole magnets from particle accelerators, wiggler magnets developed for accelerator based advanced light sources, and toroidal magnets similar to those used in particle physics detectors. We investigate the expected sensitivity of such ALP dark matter detectors and discuss the engineering aspects of building and tuning them. Brief mention is also made of even stronger field magnets that are becoming available due to improvements in magnetic technology. It is concluded that new experiments utilizing already existing magnets could greatly enlarge the mass region in searches for axion-like dark matter particles. (orig.)

  4. Static dipole magnetic susceptibilities of relativistic hydrogenlike atoms: A semianalytical approach

    Science.gov (United States)

    Poszwa, A.; Rutkowski, A.

    2007-03-01

    The binding energies and magnetic susceptibilities for states evolving from 1s1/2 , 2s1/2 , 2p1/2 , 2p3/2 , 3s1/2 , 3d3/2 , and 3d5/2 are calculated using power-series solutions of the Dirac equation for hydrogenic atoms in static and uniform magnetic B . The accuracy of the binding energies for low and medium magnetic fields exceeds that of previous variational calculations. In the low-magnetic-field limit the highly accurate values of energies are used to determine the relativistic Paschen-Back effect and relativistic magnetic susceptibilities by expansion of the fully relativistic energy into power series of the parameter B/Z2 . The linear term of this series is related to the relativistic Paschen-Back effect and the square term is proportional to the relativistic dipole magnetic susceptibility of the atom.

  5. Probing the Electromagnetic Local Density of States with a Strongly Mixed Electric and Magnetic Dipole Emitter

    CERN Document Server

    Karaveli, Sinan; Zia, Rashid

    2013-01-01

    We identify a solid-state quantum emitter whose room-temperature radiative decay is mediated by a nearly equal mixture of isotropic electric dipole (ED) and magnetic dipole (MD) transitions. Using energy-momentum spectroscopy, we experimentally show that the near-infrared $^3$T$_2{\\rightarrow}^3$A$_2$ emission from divalent-nickel-doped magnesium oxide (Ni$^{2+}$:MgO) is composed of $\\sim$50% MD and $\\sim$50% ED transitions. We then demonstrate that the spontaneous emission rate of these ions near planar interfaces is determined by the combined electric and magnetic local density of optical states (LDOS). This electromagnetic LDOS probes the total mode density, and thus similar to thermal emission, these unique electronic emitters effectively excite all polarizations and orientations of the electromagnetic field.

  6. Features of 10-M-long, 50-MM-Twin-aperture LHC dipole magnet prototypes

    Energy Technology Data Exchange (ETDEWEB)

    Devred, A. [CEA Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee]|[CERN, Laboratoire Europeen pour la Physique des Particules, Geneva (Switzerland)

    1998-03-01

    In 1991, the Laboratoire Europeen pour la Physique des particules (CERN) has launched the fabrication in industry of seven 10-m long, 50-mm-twin-aperture dipole magnet prototypes for the Large Hadron Collider (LHC). Three of these prototypes were built in Italy, in collaboration with the Istituto Nazionale di Fisica Nucleare (INFN, by Ansaldo Energia Spa, two were built in Germany by Noell GmbH, one was built in France by a consortium constituted by Jeumont Industries and GEC Alsthom, and the last one was built by a consortium constituted by Elin in Austria and Holec in the Netherlands. In this paper, we review the design and specific features of the seven LHC dipole magnet prototypes. (author) 21 refs.

  7. Chaotic Dynamics of Test Particle in the Gravitational Field with Magnetic Dipoles

    Institute of Scientific and Technical Information of China (English)

    CHEN Ju-Hua; WANG Yong-Jiu

    2003-01-01

    We investigate the dynamics of the test particle in the gravitational field with magnetic dipoles in thispaper. At first we study the gravitational potential by numerical simulations. We find, for appropriate parameters, thatthere are two different cases in the potential curve, one of which is the one-well case with a stable critical point, and theother is the three-well case with three stable critical points and two unstable ones. As a consequence, the chaotic motionwill rise. By performing the evolution of the orbits of the test particle in the phase space, we find that the orbits of thetest particle randomly oscillate without any periods, even sensitively depending on the initial conditions and parameters.chaotic motion of the test particle in the field with magnetic dipoles becomes even obvious as the value of the magneticdipoles increases.

  8. In-gas-cell laser spectroscopy for magnetic dipole moment of $^{199}$Pt toward $N=$ 126

    CERN Document Server

    Hirayama, Y; Watanabe, Y X; Jeong, S C; Jung, H S; Kakiguchi, Y; Kimura, S; Moon, J Y; Oyaizu, M; Park, J H; Schury, P; Wada, M; Miyatake, H

    2016-01-01

    Magnetic dipole moment and mean-square charge radius of $^{199}$Pt ($I^{\\pi}=$ 5/2$^-$) have been evaluated for the first time from the investigation of the hyperfine splitting of the $\\lambda_1=$ 248.792 nm transition by in-gas-cell laser ionization spectroscopy. Neutron-rich nucleus $^{199}$Pt was produced by multi-nucleon transfer reaction at the KISS where the nuclear spectroscopy in the vicinity of $N=$ 126 is planed from the aspect of an astrophysical interest as well as the nuclear structure. Measured magnetic dipole moment $+$0.63(13)$\\mu_{\\rm N}$ is consistent with the systematics of those of nuclei with $I^{\\pi}=$ 5/2$^-$. The deformation parameter $|^{1/2}|$ evaluated from the isotope shift indicates the gradual shape change to spherical shape of platinum isotopes with increasing neutron number toward $N=$ 126.

  9. Electrically Small Magnetic Dipole Antennas With Quality Factors Approaching the Chu Lower Bound

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Breinbjerg, Olav; Yaghjian, Arthur D.

    2010-01-01

    permeability yields the quality factor Q that constitutes the lower bound for a magnetic dipole antenna with a magneto-dielectric core. Furthermore, the smaller the antenna the closer its quality factor Q can approach the Chu lower bound. Simulated results for the TE10-mode multiarm spherical helix antenna......We investigate the quality factor Q for electrically small current distributions and practical antenna designs radiating the TE10 magnetic dipole field. The current distributions and the antenna designs employ electric currents on a spherical surface enclosing a magneto-dielectric material...... numerically. It is found that for a given antenna size and permittivity there is an optimum permeability that ensures the lowest possible Q, and this optimum permeability is inversely proportional to the square of the antenna electrical radius. When the relative permittivity is equal to 1, the optimum...

  10. Testing the axial dipole hypothesis for the Moon by modeling the direction of crustal magnetization

    Science.gov (United States)

    Oliveira, J. S.; Wieczorek, M. A.

    2017-02-01

    Orbital magnetic field data show that portions of the Moon's crust are strongly magnetized, and paleomagnetic data of lunar samples suggest that Earth strength magnetic fields could have existed during the first several hundred million years of lunar history. The origin of the fields that magnetized the crust are not understood and could be the result of either a long-lived core-generated dynamo or transient fields associated with large impact events. Core dynamo models usually predict that the field would be predominantly dipolar, with the dipole axis aligned with the rotation axis. We test this hypothesis by modeling the direction of crustal magnetization using a global magnetic field model of the Moon derived from Lunar Prospector and Kaguya magnetometer data. We make use of a model that assumes that the crust is unidirectionally magnetized. The intensity of magnetization can vary with the crust, and the best fitting direction of magnetization is obtained from a nonnegative least squares inversion. From the best fitting magnetization direction we obtain the corresponding north magnetic pole predicted by an internal dipolar field. Some of the obtained paleopoles are associated with the current geographic poles, while other well-constrained anomalies have paleopoles at equatorial latitudes, preferentially at 90° east and west longitudes. One plausible hypothesis for this distribution of paleopoles is that the Moon possessed a long-lived dipolar field but that the dipole was not aligned with the rotation axis as a result of large-scale heat flow heterogeneities at the core-mantle boundary.

  11. Magnetic dipole excitations in nuclei: elementary modes of nucleonic motion

    CERN Document Server

    Heyde, Kris; Richter, Achim

    2010-01-01

    The nucleus is one of the most multi-faceted many-body systems in the universe. It exhibits a multitude of responses depending on the way one 'probes' it. With increasing technical advancements of beams at the various accelerators and of detection systems the nucleus has, over and over again, surprised us by expressing always new ways of 'organized' structures and layers of complexity. Nuclear magnetism is one of those fascinating faces of the atomic nucleus we discuss in the present review. We shall not just limit ourselves to presenting the by now very large data set that has been obtained in the last two decades using various probes, electromagnetic and hadronic alike and that presents ample evidence for a low-lying orbital scissors mode around 3 MeV, albeit fragmented over an energy interval of the order of 1.5 MeV, and higher-lying spin-flip strength in the energy region 5 - 9 MeV in deformed nuclei, nor to the presently discovered evidence for low-lying proton-neutron isovector quadrupole excitations in...

  12. Chaotic Dynamics of Test Particle in the Gravitational Field with Magnetic Dipoles

    Institute of Scientific and Technical Information of China (English)

    CHENJu-Hua; WANGYong-Jiu

    2003-01-01

    We investigate the dynamics of the test particle in the gravitational field with magnetic dipoles in this paper. At first we study the gravitational potential by numerical simulations. We find, for appropriate parameters, that there are two different cases in the potential curve, one of which is the one-well case with a stable critical point, and the other is the three-well case with three stable critical points and two unstable ones. As a consequence, the chaotic motion will rise. By performing the evolution of the orbits of the test particle in the phase space, we find that the orbits of the test particle randomly oscillate without any periods, even sensitively depending on the initial conditions and parameters.By performing Poincaré sections for different values of the parameters and initial conditions, we further conform that the chaotic motion of the test particle in the field with magnetic dipoles becomes even obvious as the value of the magnetic dipoles increases.

  13. Braking Index of Isolated Pulsars II: A novel two-dipole model of pulsar magnetism

    CERN Document Server

    Hamil, Oliver Q; Stone, Jirina R

    2016-01-01

    The magnetic dipole radiation (MDR) model is currently the best approach we have to explain pulsar radiation. However a most characteristic parameter of the observed radiation, the braking index n$_{\\rm obs}$ shows deviations for all the eight best studied isolated pulsars, from the simple model prediction n$_{\\rm dip}$ = 3. The index depends upon the rotational frequency and its first and second time derivatives, but also on the assumption of that the magnetic dipole moment and inclination angle, and the moment of inertia of the pulsar are constant in time. In a recent paper [Phys. Rev. D 91, 063007 (2015)] we showed conclusively that changes in the moment of inertia with frequency alone, cannot explain the observed braking indices. Possible observational evidence for the magnetic dipole moment migrating away from the rotational axis at a rate $\\dot\\alpha$ $\\sim$ 0.6$^{\\circ}$ per 100 years over the life time of the Crab pulsar has been recently suggested by Lyne et al. In this paper, we explore the MDR mode...

  14. Dependence of Magnetic Field Quality on Collar Supplier and Dimensions in the Main LHC Dipole

    CERN Document Server

    Bellesia, B; Santoni, C; Todesco, E

    2006-01-01

    In order to keep the electro-magnetic forces and to minimize conductor movements, the superconducting coils of the main Large Hadron Collider dipoles are held in place by means of austenitic steel collars. Two suppliers provide the collars necessary for the whole LHC production, which has now reached more than 800 collared coils. In this paper we first assess if the different collar suppliers origin a noticeable difference in the magnetic field quality measured at room temperature. We then analyze the measurements of the collar dimensions carried out at the manufacturers, comparing them to the geometrical tolerances. Finally we use a magneto-static model to evaluate the expected spread in the field components induced by the actual collar dimensions. These spreads are compared to the magnetic measurements at room temperature over the magnet production in order to identify if the collars, rather than other components or assembly process, can account for the measured magnetic field effects. It has been found tha...

  15. The correlation between magneto-optical response and magnetic dipole resonance excitation in subwavelength silicon-nickel nanogratings

    Science.gov (United States)

    Musorin, A. I.; Barsukova, M. G.; Shorokhov, A. S.; Neshev, D. N.; Kivshar, Y. S.; Fedyanin, A. A.

    2017-09-01

    The advantages of gyrotopic materials are combined with the field of high-index metamaterials. The enhancement of the magneto-optical response in the spectral vicinity of the magnetic dipole resonance of a dielectric silicon nanodisks is numerically shown.

  16. Inner-shell magnetic dipole transition in Tm atom as a candidate for optical lattice clocks

    CERN Document Server

    Sukachev, D; Tolstikhina, I; Kalganova, E; Vishnyakova, G; Khabarova, K; Tregubov, D; Golovizin, A; Sorokin, V; Kolachevsky, N

    2016-01-01

    We consider a narrow magneto-dipole transition in the $^{169}$Tm atom at the wavelength of $1.14\\,\\mu$m as a candidate for a 2D optical lattice clock. Calculating dynamic polarizabilities of the two clock levels $[\\text{Xe}]4f^{13}6s^2 (J=7/2)$ and $[\\text{Xe}]4f^{13}6s^2 (J=5/2)$ in the spectral range from $250\\,$nm to $1200\\,$nm, we suggest the "magic" wavelength for the optical lattice at $807\\,$nm. Frequency shifts due to black-body radiation (BBR), the van der Waals interaction, the magnetic dipole-dipole interaction and other effects which can perturb the transition frequency are calculated. The transition at $1.14\\,\\mu$m demonstrates low sensitivity to the BBR shift corresponding to $8\\times10^{-17}$ in fractional units at room temperature which makes it an interesting candidate for high-performance optical clocks. The total estimated frequency uncertainty is less than $5 \\times 10^{-18}$ in fractional units. By direct excitation of the $1.14\\,\\mu$m transition in Tm atoms loaded into an optical dipole ...

  17. Quantitatively analyzing intrinsic plasmonic chirality by tracking the interplay of electric and magnetic dipole modes

    CERN Document Server

    Hu, Li; Fang, Yurui

    2016-01-01

    Plasmonic chirality exhibits great potential for novel nanooptical devices due to the generation of a strong chiroptical response. Previous reports on plasmonic chirality explanations are mainly based on phase retardation and coupling. We propose a quantitative model similar to the chiral molecules for explaining the mechanism of the intrinsic plasmonic chirality quantitatively based on the interplay and mixing of electric and magnetic dipole modes, which forms a mixed electric and magnetic polarizability. The analysis method is also suitable for small chiral object down to quasi-static limit without phase delay and expected to be a universal rule.

  18. Description of the Main Features of the Series Production of the LHC Main Dipole Magnets

    CERN Document Server

    Savary, F; Chevret, P; de Rijk, G; Fessia, P; Liénard, P; Miles, J; Modena, M; Rossi, L; Tommasini, D; Vlogaert, J; Bresson, D; Grunblatt, G; Decoene, JF; Bressani, F; Drago, G; Gagliardi, P; Eysselein, F; Gärtner, W; Lublow, P

    2008-01-01

    The series production of the LHC main dipole magnets was completed in November 2006. This paper presents the organization implemented at CERN and the milestones fixed to fullfil the technical requirements and to respect the master schedule of the machine installation. The CERN organization for the production follow-up, the quality assurance and the magnet testing, as well as the organization of the three main contractors will be described. A description of the design work and procurement of most of the specific heavy tooling and key components will be given with emphasis on the advantages and drawbacks.

  19. Radiation of Magnetic Dipole and Electric Quadrupole in Anisotropic Medium (Ⅱ) — Rading Electric Field

    Institute of Scientific and Technical Information of China (English)

    HONGQingquan; CHENShennian; WANGJiancheng

    2003-01-01

    Taking advantage of magnetic field ra-diated by magnetic dipole and electric quadrupole in anisotropic magnetic medium which had been calculated already, the authors go further to calculate radiating elec-tric field and to confirm the correctness of results.

  20. Bimodal distribution of the magnetic dipole moment in nanoparticles with a monomodal distribution of the physical size

    NARCIS (Netherlands)

    van Rijssel, Jozef; Kuipers, Bonny W M; Erne, Ben

    2015-01-01

    High-frequency applications of magnetic nanoparticles, such as therapeutic hyperthermia and magnetic particle imaging, are sensitive to nanoparticle size and dipole moment. Usually, it is assumed that magnetic nanoparticles with a log-normal distribution of the physical size also have a log-normal d

  1. Microgravity Electron Electric Dipole Moment Experiment with a Cold Atom Beam

    Science.gov (United States)

    Gould, Harvey

    2003-01-01

    New physics beyond the Standard Model: The small CP violation contained in the Standard Model is insufficient to account for the baryon/antibaryon asymmetry in the universe. New sources of CP violation are provided by extensions to the Standard Model. They contain CP-violating phases that couple directly to leptons and from which a large electron electric dipole moment (EDM) may be generated. Observation of an electron EDM would be proof of a Standard Model extension because the Standard Model only allows an electron EDM of less than 10(exppp -57) C-m (S.I. units; 1 C-m = 1.6 x 10(exp -21) e-cm). A null result, however, constrains models and improving the limit tightens constraints, further restricting the models.

  2. Temperature Profiles During Quenches in LHC Superconducting Dipole Magnets Protected by Quench Heaters

    CERN Document Server

    Maroussov, V; Siemko, A

    2000-01-01

    The efficiency of the magnet protection by quench heaters was studied using a novel method which derives the temperature profile in a superconducting magnet during a quench from measured voltage signals. In several Large Hadron Collider single aperture dipole models, temperature profiles and temperature gradients in the magnet coil have been evaluated in the case of protection by different sets of quench heaters and different powering and protection parameters. The influence of the insulation thickness between the quench heaters and the coil has also been considered. The results show clear correlation between the positions of quench heaters, magnet protection parameters and temperature profiles. This study allowed a better understanding of the quench process mechanisms and the efficiency assessment of the different protection schemes.

  3. Development and Coil Fabrication Test of the $Nb_3Sn$ Dipole Magnet FRESCA2

    CERN Document Server

    Manil, P; Clement, S; Devaux, M; Durante, M; Fazilleau, P; Ferracin, P; Fessia, P; Munoz Garcia, J E; Garcia, L; Gauthier, R; Oberli, L; Perez, J C; Pietrowicz, S; Rifflet, J M; de Rijk, G; Rondeaux, F; Todesco, E

    2014-01-01

    The key objective of the High Field Magnet work package of the European Project EuCARD is to design and fabricate the Nb3Sn dipole magnet FRESCA2. It has an aperture of 100 mm and a target bore field of 13 T. The design features four 1.5 m long double-layer coils wound with a 21 mm wide cable. The project has now entered its experimental phase in view of the magnet fabrication. We present the experimental test campaign conducted on cable samples in order to understand and to control better the cable behavior and geometry. One full scale double-layer coil using copper cable with the final dimensions and insulation scheme has been wound and heat treated in order to check the fabrication process. This has given useful feedback on the fabrication procedure and on the expected magnet dimensions, as well as on the tooling itself.

  4. The dipole corrector magnets for the RHIC fast global orbit feedback system

    Energy Technology Data Exchange (ETDEWEB)

    Thieberger, P.; Arnold, L.; Folz, C.; Hulsart, R.; Jain, A.; Karl, R.; Mahler, G.; Meng, W.; Mernick, K.; Michnoff, R.; Minty, M.; Montag, C.; Ptitsyn, V.; Ritter, J.; Smart, L.; Tuozzolo, J.; White, J.

    2011-03-28

    The recently completed RHIC fast global orbit feedback system uses 24 small 'window-frame' horizontal dipole correctors. Space limitations dictated a very compact design. The magnetic design and modelling of these laminated yoke magnets is described as well as the mechanical implementation, coil winding, vacuum impregnation, etc. Test procedures to determine the field quality and frequency response are described. The results of these measurements are presented and discussed. A small fringe field from each magnet, overlapping the opposite RHIC ring, is compensated by a correction winding placed on the opposite ring's magnet and connected in series with the main winding of the first one. Results from measurements of this compensation scheme are shown and discussed.

  5. submitter Status of the EuCARD 5.4-T REBCO Dipole Magnet

    CERN Document Server

    Borgnolutti, F; Debray, F; Rifflet, J -M; De Rijk, G; Tixador, P; Tudela, J -M

    2016-01-01

    A 5.4-T REBCO insert dipole magnet is being built at CEA Saclay to study the viability of hybrid accelerator magnets made of high- and low-temperature superconductors to generate magnetic fields in the range of 20 T, which is a field level of interest for future circular colliders. In this paper, we present the electromechanical design of the insert. It is a mechanically more robust version of the baseline design, which was produced in the framework of the former EuCARD program. The fabrication of a prototype made with dummy coils is discussed, and the impact of persistent currents on the central magnetic field is estimated using a 2-D electromagnetic model

  6. Bimodal distribution of the magnetic dipole moment in nanoparticles with a monomodal distribution of the physical size

    Energy Technology Data Exchange (ETDEWEB)

    Rijssel, Jos van; Kuipers, Bonny W.M.; Erné, Ben H., E-mail: B.H.Erne@uu.nl

    2015-04-15

    High-frequency applications of magnetic nanoparticles, such as therapeutic hyperthermia and magnetic particle imaging, are sensitive to nanoparticle size and dipole moment. Usually, it is assumed that magnetic nanoparticles with a log-normal distribution of the physical size also have a log-normal distribution of the magnetic dipole moment. Here, we test this assumption for different types of superparamagnetic iron oxide nanoparticles in the 5–20 nm range, by multimodal fitting of magnetization curves using the MINORIM inversion method. The particles are studied while in dilute colloidal dispersion in a liquid, thereby preventing hysteresis and diminishing the effects of magnetic anisotropy on the interpretation of the magnetization curves. For two different types of well crystallized particles, the magnetic distribution is indeed log-normal, as expected from the physical size distribution. However, two other types of particles, with twinning defects or inhomogeneous oxide phases, are found to have a bimodal magnetic distribution. Our qualitative explanation is that relatively low fields are sufficient to begin aligning the particles in the liquid on the basis of their net dipole moment, whereas higher fields are required to align the smaller domains or less magnetic phases inside the particles. - Highlights: • Multimodal fits of dilute ferrofluids reveal when the particles are multidomain. • No a priori shape of the distribution is assumed by the MINORIM inversion method. • Well crystallized particles have log-normal TEM and magnetic size distributions. • Defective particles can combine a monomodal size and a bimodal dipole moment.

  7. Hyperfine-induced electric dipole contributions to the electric octupole and magnetic quadrupole atomic clock transitions

    CERN Document Server

    Dzuba, V A

    2016-01-01

    Hyperfine-induced electric dipole contributions may significantly increase probabilities of otherwise very weak electric octupole and magnetic quadrupole atomic clock transitions (e.g. transitions between $s$ and $f$ electron orbitals). These transitions can be used for exceptionally accurate atomic clocks, quantum information processing and search for dark matter. They are very sensitive to new physics beyond the Standard Model, such as temporal variation of the fine structure constant, the Lorentz invariance and Einstein equivalence principle violation. We formulate conditions under which the hyperfine-induced electric dipole contribution dominates. Due to the hyperfine quenching the electric octupole clock transition in $^{173}$Yb$^+$ is two orders of magnitude stronger than that in currently used $^{171}$Yb$^+$. Some enhancement is found in $^{143}$Nd$^{13+}$, $^{149}$Pm$^{14+}$, $^{147}$Sm$^{14+}$, and $^{147}$Sm$^{15+}$ ions.

  8. Risk Assessment of the Chopper Dipole Kicker Magnets for the MedAustron Facility

    CERN Document Server

    Kramer, T; Barnes, M J; Benedikt, M; Fowler, T

    2011-01-01

    The MedAustron facility, to be built in Wiener Neustadt (Austria), will provide protons and ions for both cancer therapy and research [1]. Different types of kicker magnets will be used in the accelerator complex, including fast beam chopper dipoles: these allow the beam to be switched on and off for routine operational reasons or in case of emergency. Main requirements for the beam chopper system are safety and reliability. A criticality analysis, to chart the probability of failure modes against the severity of their consequences of the fault, has been carried out for the chopper dipole system. This "Failure Mode, Effects, and Criticality Analysis" (FMECA), has been used to highlight failure modes with relatively high probability and severity of consequences: conservative ratings of critical components and appropriate redundancy, together with measurements and interlocks, have been used to reduce the probability and criticality of faults. This paper gives an overview of the Risk Assessment approach and pres...

  9. Comparison of 2-D Magnetic Designs of Selected Coil Configurations for the Next European Dipole (NED)

    CERN Document Server

    Toral, F; Felice, H; Fessia, Paolo; Loveridge, P W; Regis, Federico; Rochford, J; Sanz, S; Schwerg, Nikolai; Védrine, P; Völlinger, Christine

    2007-01-01

    The Next European Dipole (NED) activity is developing a high-performance Nb3Sn wire (aiming at a non-copper critical current density of 1500 A/mm2 at 4.2 K and 15 T), within the framework of the Coordinated Accelerator Research in Europe (CARE) project. This activity is expected to lead to the fabrication of a large aperture, high field dipole magnet. In preparation for this phase, a Working Group on Magnet Design and Optimization (MDO) has been established to propose an optimal design. Other parallel Work Packages are concentrating on relevant topics, such as quench propagation simulation, innovative insulation techniques, and heat transfer measurements. In a first stage, the MDO Working Group has selected a number of coil configurations to be studied, together with salient parameters and features to be considered during the evaluation: the field quality, the superconductor efficiency, the conductor peak field, the stored magnetic energy, the Lorentz Forces and the fabrication difficulties. 2-D magnetic calc...

  10. Recent developments in semiprocessed cold rolled magnetic lamination steel

    Science.gov (United States)

    Hilinski, E. J.

    2006-09-01

    Over the past 10 years the magnetic property performance of semi-processed cold rolled magnetic lamination steels in North America have approached those of nonoriented, semi-processed silicon steel. This improvement was accomplished via higher alloy levels in conjunction with hot band annealing. New temper rolling strategies can produce weakly oriented steels tailored to specific applications, such as small transformers used in fluorescent lighting ballasts. Recently, production trials for 0.0138 in product cold rolled on tin mills has been undertaken. Efforts to further improve properties through a better understanding of texture control and via implementation of new production processes, such as thin slab or strip casting, continue.

  11. Design and analysis of the tooling upgrade for the production of the superconductive main dipole magnet prototypes of LHC

    CERN Document Server

    AUTHOR|(CDS)2093638

    Design and analysis of the tooling upgrade for the production of the superconductive main dipole magnet prototypes of LHC Master of Science Thesis, 110 pages, 12 Appendix pages September 2013 Major: Design of machines and systems Examiner: Professor Reijo Kouhia Keywords: CERN, LHC, High Luminosity LHC project, superconductive dipole magnet, welding press, Nb3Sn, pre-stress, Ar-inert gas furnace This thesis work has been carried out as a contribution to the development program of superconductive magnets within the LHC High Luminosity study. The thesis provides an insight to the steps that need to be taken in order to produce a superconductive magnet mainly focusing on mechanical assembly. Tooling upgrade is necessary for the production of the superconductive dipole magnet prototypes in near future. Major attention is given by the introduction of the welding assembly in chapter three. The structural compression is given by the so called shell stress defined by the thermal shrinkage of the weld. The associated ...

  12. Surface temperature of a magnetized neutron star and interpretation of the ROSAT data. 1: Dipole fields

    Science.gov (United States)

    Page, Dany

    1995-01-01

    We model the temperature distribution at the surface of a magnetized neutron star and study the effects on the observed X-ray spectra and light curves. Generalrelativistic effects, i.e., redshift and lensing, are fully taken into account. Atmospheric effects on the emitted spectral flux are not included: we consider only blackbody emission at the local effective temperature. In this first paper we restrict ourselves to dipole fields. General features are studied and compared with the ROSAT data from the pulsars 0833 - 45 (Vela), 0656 + 14, 0630 + 178 (Geminga), and 1055 - 52, the four cases for which there is strong evidence that thermal radiation from the stellar surface is detected. The composite spectra we obtain are not very different from a blackbody spectrum at the star's effective temperature. We conclude that, as far as blackbody spectra are considered, temperature estimates using single-temperature models give results practically identical to our composite models. The change of the (composite blackbody) spectrum with the star's rotational phase is also not very large and may be unobservable inmost cases. Gravitational lensing strongly suppresses the light curve pulsations. If a dipole field is assumed, pulsed fractions comparable to the observed ones can be obtained only with stellar radii larger than those which are predicted by current models of neutron star struture, or with low stellar masses. Moreover, the shapes of the theoretical light curves with dipole fields do not correspond to the observations. The use of magnetic spectra may raise the pulsed fraction sufficiently but will certainly make the discrepancy with the light curve shapes worse: dipole fields are not sufficient to interpret the data. Many neutron star models with a meson condensate or hypersons predict very small radii, and hence very strong lensing, which will require highly nondipolar fields to be able to reproduce the observed pulsed fractions, if possible at all: this may be a new

  13. Saturn's Magnetic Field Model: Birotor Dipole From Cassini RPWS and MAG Experiments

    Science.gov (United States)

    Galopeau, P. H. M.

    2016-12-01

    The radio and plasma wave science (RPWS) experiment on board the Cassini spacecraft, orbiting around Saturn since July 2004, revealed the presence of two distinct and variable rotation periods in the Saturnian kilometric radiation (SKR) which were attributed to the northern and southern hemispheres respectively. We believe that the periodic time modulations present in the SKR are mainly due to the rotation of Saturn's inner magnetic field. The existence of a double period implies that the inner field is not only limited to a simple rotation dipole but displays more complex structures having the same time periodicities than the radio emission. In order to build a model of this complex magnetic field, it is absolutely necessary to know the accurate phases of rotation linked with the two periods. The radio observations from the RPWS experiment allow a continuous and accurate follow-up of these rotation phases, since the SKR emission is permanently observable and produced very close to the planetary surface. A wavelet transform analysis of the intensity of the SKR signal received at 290 kHz between July 2004 and June 2012 was performed in order to calculate in the same time the different periodicities and phases. A dipole model was proposed for Saturn's inner magnetic field: this dipole presents the particularity to have North and South poles rotating around Saturn's axis at two different angular velocities; this dipole is tilted and not centered. 57 Cassini's revolutions, the periapsis of which is less than 5 Saturnian radii, have been selected for this study. For each of these chosen orbits, it is possible to fit with high precision the measurements of the MAG data experiment given by the magnetometers embarked on board Cassini. A nonrotating external magnetic field completes the model. This study suggests that Saturn's inner magnetic field is neither stationary nor fully axisymmetric. These results can be used as a boundary condition for modelling and constraining

  14. Concentration dependence of the wings of a dipole-broadened magnetic resonance line in magnetically diluted lattices

    Energy Technology Data Exchange (ETDEWEB)

    Zobov, V. E., E-mail: rsa@iph.krasn.ru [Russian Academy of Sciences, Kirenskii Institute of Physics, Siberian Branch (Russian Federation); Kucherov, M. M. [Siberian Federal University, Institute of Space and Information Technologies (Russian Federation)

    2017-01-15

    The singularities of the time autocorrelation functions (ACFs) of magnetically diluted spin systems with dipole–dipole interaction (DDI), which determine the high-frequency asymptotics of autocorrelation functions and the wings of a magnetic resonance line, are studied. Using the self-consistent fluctuating local field approximation, nonlinear equations are derived for autocorrelation functions averaged over the independent random arrangement of spins (magnetic atoms) in a diamagnetic lattice with different spin concentrations. The equations take into account the specificity of the dipole–dipole interaction. First, due to its axial symmetry in a strong static magnetic field, the autocorrelation functions of longitudinal and transverse spin components are described by different equations. Second, the long-range type of the dipole–dipole interaction is taken into account by separating contributions into the local field from distant and near spins. The recurrent equations are obtained for the expansion coefficients of autocorrelation functions in power series in time. From them, the numerical value of the coordinate of the nearest singularity of the autocorrelation function is found on the imaginary time axis, which is equal to the radius of convergence of these expansions. It is shown that in the strong dilution case, the logarithmic concentration dependence of the coordinate of the singularity is observed, which is caused by the presence of a cluster of near spins whose fraction is small but contribution to the modulation frequency is large. As an example a silicon crystal with different {sup 29}Si concentrations in magnetic fields directed along three crystallographic axes is considered.

  15. Compensation of Third-Harmonic Field Error in the Main Dipole Magnets

    CERN Document Server

    Arpaia, P; Fiscarelli, L; Montenero, G; Garcia Perez, J; Walckiers, L

    2010-01-01

    One of the main requirements for the operations of the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) is a suitable correction of multipole errors in magnetic field. The feed-forward control of the LHC is based on the Field Description for the LHC (FiDel), capable of forecasting the magnet’s behavior in order to generate adequate current ramps for main and corrector magnets. Magnetic measurements campaigns aimed at validating the model underlying FiDel highlighted the need for improving the harmonic compensation of the third-harmonic (b3) component of the main LHC dipoles. In this paper, the results of a new measurement campaign for b3 harmonic compensation, carried out through the new Fast Acquisition Measurement Equipment (FAME), are reported. In particular, the mechanism and the measurement procedure of the compensation, as well as the new perspectives opened by preliminary experimental results, are illustrated.

  16. Spin dephasing in a magnetic dipole field around large capillaries: Approximative and exact results

    Science.gov (United States)

    Kurz, F. T.; Buschle, L. R.; Kampf, T.; Zhang, K.; Schlemmer, H. P.; Heiland, S.; Bendszus, M.; Ziener, C. H.

    2016-12-01

    We present an analytical solution of the Bloch-Torrey equation for local spin dephasing in the magnetic dipole field around a capillary and for ensembles of capillaries, and adapt this solution for the study of spin dephasing around large capillaries. In addition, we provide a rigorous mathematical derivation of the slow diffusion approximation for the spin-bearing particles that is used in this regime. We further show that, in analogy to the local magnetization, the transverse magnetization of one MR imaging voxel in the regime of static dephasing (where diffusion effects are not considered) is merely the first term of a series expansion that constitutes the signal in the slow diffusion approximation. Theoretical results are in agreement with experimental data for capillaries in rat muscle at 7 T.

  17. (129) Xe and (131) Xe nuclear magnetic dipole moments from gas phase NMR spectra.

    Science.gov (United States)

    Makulski, Włodzimierz

    2015-04-01

    (3) He, (129) Xe and (131) Xe NMR measurements of resonance frequencies in the magnetic field B0=11.7586 T in different gas phase mixtures have been reported. Precise radiofrequency values were extrapolated to the zero gas pressure limit. These results combined with new quantum chemical values of helium and xenon nuclear magnetic shielding constants were used to determine new accurate nuclear magnetic moments of (129) Xe and (131) Xe in terms of that of the (3) He nucleus. They are as follows: μ((129) Xe) = -0.7779607(158)μN and μ((131) Xe) = +0.6918451(70)μN . By this means, the new 'helium method' for estimations of nuclear dipole moments was successfully tested. Gas phase NMR spectra demonstrate the weak intermolecular interactions observed on the (3) He and (129) Xe and (131) Xe shielding in the gaseous mixtures with Xe, CO2 and SF6 .

  18. Observation of cold Rb{sub 2} molecules trapped in an optical dipole trap using a laser-pulse-train technique

    Energy Technology Data Exchange (ETDEWEB)

    Menegatti, Carlos R.; Marangoni, Bruno S.; Marcassa, Luis G. [Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Caixa Postal 369, 13560-970, Sao Carlos, SP (Brazil)

    2011-11-15

    In this work, we have developed and characterized a laser-pulse-train technique to observe cold Rb{sub 2} molecules trapped in an optical dipole trap. The molecules are produced in a magneto-optical trap, and then loaded into a crossed optical dipole trap. The time evolution of the molecular population is obtained by applying a laser pulse train, which photoionizes the ground-state molecules through intermediate molecular bands. Our results show that this technique allows us to obtain a faster data acquisition rate of the time evolution of the molecule population than other techniques.

  19. Dipolar relaxation of cold sodium atoms in a magnetic field

    CERN Document Server

    Zygelman, B

    2002-01-01

    A quantum mechanical close coupling theory of spin relaxation in the stretched hyperfine level of sodium is presented. We calculate the dipolar relaxation rate of magnetically trapped cold sodium atoms in the magnetic field. The influence of shape resonances and the anisotropy of the dipolar interaction on the collision dynamics are explored. We examine the sensitivity of the calculated cross sections on the choice of asymptotic atomic state basis.

  20. Design of a Large Single-Aperture Dipole Magnet for HL-LHC Upgrade

    CERN Document Server

    Qingjin, Xu; Iio, Masami; Ogitsu, Toru; Sasaki, Kenichi; Yamamoto, Akira; Todesco, Ezio

    2013-01-01

    An upgrade of the low-beta insertion system for the ATLAS and Compact Muon Solenoid experiments is proposed in the high luminosity Large Hadron Collider upgrade project. It includes final beam focusing quadrupoles, beam separation and recombination dipoles, and larger aperture matching section quadrupoles. KEK is in charge of the conceptual design of the large aperture separation dipole D1. The latest design parameters are a main field of ~ 5 T at 1.9 K with Nb-Ti superconducting technology, a coil aperture of 160 mm, and a cos-theta one-layer coil with Large Hadron Collider dipole cable. Because the new D1 is expected to be operated in a very high radiation environment, radiation resistance and a cooling scheme are being carefully considered. The collaring-yoke structure is adopted to provide the mechanical support for the single-layer Nb-Ti coil. We summarize the design study of this magnet, including i) the very large iron saturation effect on field quality due to the large aperture and limited size of the...

  1. Diffusion-mediated dephasing in the dipole field around a single spherical magnetic object.

    Science.gov (United States)

    Buschle, Lukas R; Kurz, Felix T; Kampf, Thomas; Triphan, Simon M F; Schlemmer, Heinz-Peter; Ziener, Christian Herbert

    2015-11-01

    In this work, the time evolution of the free induction decay caused by the local dipole field of a spherical magnetic perturber is analyzed. The complicated treatment of the diffusion process is replaced by the strong-collision-approximation that allows a determination of the free induction decay in dependence of the underlying microscopic tissue parameters such as diffusion coefficient, sphere radius and susceptibility difference. The interplay between susceptibility- and diffusion-mediated effects yields several dephasing regimes of which, so far, only the classical regimes of motional narrowing and static dephasing for dominant and negligible diffusion, respectively, were extensively examined. Due to the asymmetric form of the dipole field for spherical objects, the free induction decay exhibits a complex component in contradiction to the cylindrical case, where the symmetric local dipole field only causes a purely real induction decay. Knowledge of the shape of the corresponding frequency distribution is necessary for the evaluation of more sophisticated pulse sequences and a detailed understanding of the off-resonance distribution allows improved quantification of transverse relaxation.

  2. Studies of Beam Induced Electron Cloud Resonances in Dipole Magnetic Fields

    CERN Document Server

    Calvey, J R; Makita, J; Venturini, M

    2016-01-01

    The buildup of low energy electrons in an accelerator, known as electron cloud, can be severely detrimental to machine performance. Under certain beam conditions, the beam can become resonant with the cloud dynamics, accelerating the buildup of electrons. This paper will examine two such effects: multipacting resonances, in which the cloud development time is resonant with the bunch spacing, and cyclotron resonances, in which the cyclotron period of electrons in a magnetic field is a multiple of bunch spacing. Both resonances have been studied directly in dipole fields using retarding field analyzers installed in the Cornell Electron Storage Ring (CESR). These measurements are supported by both analytical models and computer simulations.

  3. New method to determine proton trajectories in the equatorial plane of a dipole magnetic field.

    Science.gov (United States)

    Ioanoviciu, Damaschin

    2015-01-01

    A parametric description of proton trajectories in the equatorial plane of Earth's dipole magnetic field has been derived. The exact expression of the angular coordinate contains an integral to be performed numerically. The radial coordinate results from the initial conditions by basic mathematical operations and by using trigonometric functions. With the approximate angular coordinate formula, applicable for a wide variety of cases of protons trapped in Earth's radiation belts, no numerical integration is needed. The results of exact and approximate expressions were compared for a specific case and small differences were found.

  4. Second order optical nonlinearity of graphene due to electric quadrupole and magnetic dipole effects

    Science.gov (United States)

    Cheng, J. L.; Vermeulen, N.; Sipe, J. E.

    2017-01-01

    We present a practical scheme to separate the contributions of the electric quadrupole-like and the magnetic dipole-like effects to the forbidden second order optical nonlinear response of graphene, and give analytic expressions for the second order optical conductivities, calculated from the independent particle approximation, with relaxation described in a phenomenological way. We predict strong second order nonlinear effects, including second harmonic generation, photon drag, and difference frequency generation. We discuss in detail the controllability of these effects by tuning the chemical potential, taking advantage of the dominant role played by interband optical transitions in the response. PMID:28262762

  5. The Dependence of the Field Decay on the Powering History of the LHC Superconducting Dipole Magnets

    CERN Document Server

    Sammut, N; Micallef, J; Sanfilippo, S

    2006-01-01

    The decay of the allowed multipoles in the Large Hadron Collider (LHC) dipoles is expected to perturb the beam stability during the particle injection. The decay amplitude is largely affected by the powering history of the magnet and is particularly dependent on the pre-cycle flat-top current and duration as well as the pre-injection preparation duration. With possible prospects of having different genres of cycles during the LHC operation, the powering history effect must be taken into account in the Field Description Model for the LHC and must hence be corrected during machine operation. This paper presents the results of the modelling of this phenomenon.

  6. arXiv Feasibility of measuring the magnetic dipole moments of the charm baryons at the LHC using bent crystals

    CERN Document Server

    Bezshyyko, O.A.; Fomin, A.S.; Fomin, S.P.; Kirillin, I.V.; Korchin, A. Yu.; Massacrier, L.; Natochii, A.; Robbe, P.; Scandale, W.; Shul'ga, N.F.; Stocchi, A.

    2017-08-28

    In this paper we revisit the idea of measuring the magnetic dipole moments of the charm baryons and, in particular, of charmed Lambda by studying the spin precession induced by the strong effective magnetic field inside the channels of a bent crystal. We present a detailed sensitivity study showing the feasibility of such an experiment at the LHC in the coming years.

  7. Birotor dipole model for Saturn's inner magnetic field from CASSINI RPWS measurements and MAG data

    Science.gov (United States)

    Galopeau, Patrick H. M.

    2016-10-01

    The radio and plasma wave science (RPWS) experiment on board the Cassini spacecraft, orbiting around Saturn since July 2004, revealed the presence of two distinct and variable rotation periods in the Saturnian kilometric radiation (SKR). These two periods were attributed to the northern and southern hemispheres respectively. The existence of a double period makes the study of the planetary magnetic field much more complicated and the building of a field model, based on the direct measurements of the MAG experiment from the magnetometers embarked on board Cassini, turns out to be uncertain. The first reason is the difficulty for defining a longitude system linked to the variable period, because the internal magnetic field measurements from MAG are not continuous. The second reason is the existence itself of two distinct periods which could imply the existence of a double rotation magnetic structure generated by Saturn's dynamo. However, the radio observations from the RPWS experiment allow a continuous and accurate follow-up of the rotation phase of the variable two periods, since the SKR emission is permanently observable and produced very close to the planetary surface. A wavelet transform analysis of the intensity of the SKR signal received at 290 kHz was performed in order to calculate the rotation phase of each Saturnian hemisphere. A dipole model was proposed for Saturn's inner magnetic field: this dipole presents the particularity to rotate around Saturn's axis at two different angular velocities; it is tilted and not centered. Then it is possible to fit the MAG data for each Cassini's revolution around the planet the periapsis of which is less than 5 Saturnian radii. This study suggests that Saturn's inner magnetic field is neither stationary nor fully axisymmetric. Such a result can be used as a boundary condition for modelling and constraining the planetary dynamo.

  8. Magnetized plasminos in cold and hot QED plasmas

    CERN Document Server

    Sadooghi, N

    2015-01-01

    The complete quasi-particle spectrum of a magnetized electromagnetic plasma is systematically explored at zero and nonzero temperatures. To this purpose, the general structure of the one-loop corrected propagator of magnetized fermions is determined, and the dispersion relations arising from the pole of this propagator are numerically solved. It turns out that in the lowest Landau level, where only one spin direction is allowed, the spectrum consists of one positively (negatively) charged fermionic mode with positive (negative) spin. In contrast, in higher Landau levels, as an indirect consequence of the double spin degeneracy of fermions, the spectrum consists of two massless collective modes with left- and right-chiralities. The mechanism through which these new collective excitations are created in a uniform magnetic field is similar to the production mechanism of dynamical holes (plasminos) at finite temperature and zero magnetic fields. Whereas cold magnetized plasminos appear for moderate magnetic field...

  9. Imparting magnetic dipole heterogeneity to internalized iron oxide nanoparticles for microorganism swarm control

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Paul Seung Soo, E-mail: psk25@drexel.edu [Drexel University, Department of Mechanical Engineering and Mechanics (United States); Becker, Aaron, E-mail: aaron.becker@childrens.harvard.edu [Harvard University, Department of Cardiovascular Surgery (United States); Ou, Yan, E-mail: ouy2@rpi.edu; Julius, Anak Agung, E-mail: agung@rpi.edu [Rensselaer Polytechnic Institute, Department of Electrical, Computer, and Systems Engineering (United States); Kim, Min Jun, E-mail: mkim@coe.drexel.edu [Drexel University, Department of Mechanical Engineering and Mechanics (United States)

    2015-03-15

    Tetrahymena pyriformis is a single cell eukaryote that can be modified to respond to magnetic fields, a response called magnetotaxis. Naturally, this microorganism cannot respond to magnetic fields, but after modification using iron oxide nanoparticles, cells are magnetized and exhibit a constant magnetic dipole strength. In experiments, a rotating field is applied to cells using a two-dimensional approximate Helmholtz coil system. Using rotating magnetic fields, we characterize discrete cells’ swarm swimming which is affected by several factors. The behavior of the cells under these fields is explained in detail. After the field is removed, relatively straight swimming is observed. We also generate increased heterogeneity within a population of cells to improve controllability of a swarm, which is explored in a cell model. By exploiting this straight swimming behavior, we propose a method to control discrete cells utilizing a single global magnetic input. Successful implementation of this swarm control method would enable teams of microrobots to perform a variety of in vitro microscale tasks impossible for single microrobots, such as pushing objects or simultaneous micromanipulation of discrete entities.

  10. Stress management as an enabling technology for high-field superconducting dipole magnets

    Science.gov (United States)

    Holik, Eddie Frank, III

    This dissertation examines stress management and other construction techniques as means to meet future accelerator requirement demands by planning, fabricating, and analyzing a high-field, Nb3Sn dipole. In order to enable future fundamental research and discovery in high energy accelerator physics, bending magnets must access the highest fields possible. Stress management is a novel, propitious path to attain higher fields and preserve the maximum current capacity of advanced superconductors by managing the Lorentz stress so that strain induced current degradation is mitigated. Stress management is accomplished through several innovative design features. A block-coil geometry enables an Inconel pier and beam matrix to be incorporated in the windings for Lorentz Stress support and reduced AC loss. A laminar spring between windings and mica paper surrounding each winding inhibit any stress transferral through the support structure and has been simulated with ALGORRTM. Wood's metal filled, stainless steel bladders apply isostatic, surface-conforming preload to the pier and beam support structure. Sufficient preload along with mica paper sheer release reduces magnet training by inhibiting stick-slip motion. The effectiveness of stress management is tested with high-precision capacitive stress transducers and strain gauges. In addition to stress management, there are several technologies developed to assist in the successful construction of a high-field dipole. Quench protection has been designed and simulated along with full 3D magnetic simulation with OPERARTM. Rutherford cable was constructed, and cable thermal expansion data was analysed after heat treatment. Pre-impregnation analysis techniques were developed due to elemental tin leakage in varying quantities during heat treatment from each coil. Robust splicing techniques were developed with measured resistivites consistent with nO joints. Stress management has not been incorporated by any other high field dipole

  11. Magnetic Trapping of Cold Bromine Atoms

    CERN Document Server

    Rennick, C J; Doherty, W G; Softley, T P

    2014-01-01

    Magnetic trapping of bromine atoms at temperatures in the milliKelvin regime is demonstrated for the first time. The atoms are produced by photodissociation of Br$_2$ molecules in a molecular beam. The lab-frame velocity of Br atoms is controlled by the wavelength and polarization of the photodissociation laser. Careful selection of the wavelength results in one of the pair of atoms having sufficient velocity to exactly cancel that of the parent molecule, and it remains stationary in the lab frame. A trap is formed at the null point between two opposing neodymium permanent magnets. Dissociation of molecules at the field minimum results in the slowest fraction of photofragments remaining trapped. After the ballistic escape of the fastest atoms, the trapped slow atoms are only lost by elastic collisions with the chamber background gas. The measured loss rate is consistent with estimates of the total cross section for only those collisions transferring sufficient kinetic energy to overcome the trapping potential...

  12. Magnetic trapping of cold bromine atoms.

    Science.gov (United States)

    Rennick, C J; Lam, J; Doherty, W G; Softley, T P

    2014-01-17

    Magnetic trapping of bromine atoms at temperatures in the millikelvin regime is demonstrated for the first time. The atoms are produced by photodissociation of Br2 molecules in a molecular beam. The lab-frame velocity of Br atoms is controlled by the wavelength and polarization of the photodissociation laser. Careful selection of the wavelength results in one of the pair of atoms having sufficient velocity to exactly cancel that of the parent molecule, and it remains stationary in the lab frame. A trap is formed at the null point between two opposing neodymium permanent magnets. Dissociation of molecules at the field minimum results in the slowest fraction of photofragments remaining trapped. After the ballistic escape of the fastest atoms, the trapped slow atoms are lost only by elastic collisions with the chamber background gas. The measured loss rate is consistent with estimates of the total cross section for only those collisions transferring sufficient kinetic energy to overcome the trapping potential.

  13. Estimation of the Required Amount of Superconductors for High-field Accelerator Dipole Magnets

    CERN Document Server

    Schwerg, N

    2007-01-01

    The coil size and the corresponding amount of superconducting material that is used during the design process of a magnet cross-section have direct impacts on the overall magnet cost. It is therefore of interest to estimate the minimum amount of conductors needed to reach the defined field strength before a detailed design process starts. Equally, it is useful to evaluate the efficiency of a given design by calculating the amount of superconducting cables that are used to reach the envisaged main field by simple rule. To this purpose, the minimum amount of conductors for the construction of a dipole of given main field strength and aperture size is estimated taking the actual critical current density of the used strands into account. Characteristic curves applicable for the NED Nb3Sn strand specification are given and some of the recently studied different dipole configurations are compared. Based on these results, it is shown how the required amount of conductors changes due to the iron yoke contribution and...

  14. Scaling behavior of the dipole-coupling energy in two-dimensional disordered magnetic nanostructures

    Science.gov (United States)

    Jensen, P. J.; Pastor, G. M.

    2003-11-01

    Numerical calculations of the average dipole-coupling energy Edip in two-dimensional disordered magnetic nanostructures are performed as a function of the particle coverage C. We observe that Edip scales as Edip∝Cα* with an unusually small exponent α*≃0.8 1.0 for coverages C≲20%. This behavior is shown to be primarily given by the contributions of particle pairs at short distances, which is intrinsically related to the presence of an appreciable degree of disorder. The value of α* is found to be sensitive to the magnetic arrangement within the nanostructure and to the degree of disorder. For large coverages C≳20% we obtain Edip∝Cα with α=3/2, in agreement with the straightforward scaling of the dipole coupling as in a periodic particle setup. Taking into account the effect of single-particle anisotropies, we show that the scaling exponent can be used as a criterion to distinguish between weakly interacting (α*≃1.0) and strongly interacting (α*≃0.8) particle ensembles as a function of coverage.

  15. Considerations on a Cost Model for High-Field Dipole Arc Magnets for FCC

    CERN Document Server

    AUTHOR|(CDS)2078700; Durante, Maria; Lorin, Clement; Martinez, Teresa; Ruuskanen, Janne; Salmi, Tiina; Sorbi, Massimo; Tommasini, Davide; Toral, Fernando

    2017-01-01

    In the frame of the European Circular Collider (EuroCirCol), a conceptual design study for a post-Large Hadron Collider (LHC) research infrastructure based on an energy-frontier 100 TeV circular hadron collider [1]–[3], a cost model for the high-field dipole arc magnets is being developed. The aim of the cost model in the initial design phase is to provide the basis for sound strategic decisions towards cost effective designs, in particular: (A) the technological choice of superconducting material and its cost, (B) the target performance of Nb3Sn superconductor, (C) the choice of operating temperature (D) the relevant design margins and their importance for cost, (E) the nature and extent of grading, and (F) the aperture’s influence on cost. Within the EuroCirCol study three design options for the high field dipole arc magnets are under study: cos − θ [4], block [5], and common-coil [6]. Here, in the advanced design phase, a cost model helps to (1) identify the cost drivers and feed-back this informati...

  16. Magnetic dipole interaction and line widths in NQR: 35Cl NQR spectrum of chloroform

    Science.gov (United States)

    Subramanian, V. Harihara; Narasimhan, P. T.

    35 Cl NQR spectra of CHC1 3 and CDCl 3 have been recorded at 77 K with an injection and phase-locked NQR spectrometer. The theoretical 35Cl NQR spectrum of CHC1 3 has been computed with the inclusion of H-C1 intramolecular magnetic dipole Interaction In the quadrupole Hamiltonian. It has been possible to obtain the H-C1 internuclear distance in the CHC1 3 molecule by assuming that contributions to 35Cl NQR line width from static electric effects and relaxation effects are the same in CHC1 3 and CDCl 3 and that the magnetic dipole interaction contribution to 35Cl NQR line width in CDCl 3 is negligible. The calculated H-C1 distance values are: 2.34 Å for the 'a' site and 2.49 Å for the 'b' site. These values may be compared with the x-ray value of 2.31 Å. It has also been possible to assign the observed NQR frequencies to the appropriate chlorine sites in the unit cell.

  17. Regular and Chaotic Motion in General Relativity: The Case of a Massive Magnetic Dipole

    CERN Document Server

    Kopáček, Ondřej; Karas, Vladimír; Kojima, Yasufumi

    2014-01-01

    Circular motion of particles, dust grains and fluids in the vicinity of compact objects has been investigated as a model for accretion of gaseous and dusty environment. Here we further discuss, within the framework of general relativity, figures of equilibrium of matter under the influence of combined gravitational and large-scale magnetic fields, assuming that the accreted material acquires a small electric charge due to interplay of plasma processes and photoionization. In particular, we employ an exact solution describing the massive magnetic dipole and we identify the regions of stable motion. We also investigate situations when the particle dynamics exhibits the onset of chaos. In order to characterize the measure of chaoticness we employ techniques of Poincar\\'e surfaces of section and of recurrence plots.

  18. Magnetic field component demonstration for a neutron electric dipole moment search

    Science.gov (United States)

    Slutsky, Simon

    2016-09-01

    A neutron electric dipole moment (EDM) search at the Oak Ridge National Laboratory's Spallation Neutron Source (SNS) will probe with a sensitivity of EDM will appear as a variation in the precession frequency correlated with the electric field. Magnetic field gradients must be kept below 10 pT/cm to mitigate false EDMs produced by the geometric phase effect and to maximize the neutron spin-relaxation lifetime. I will discuss a prototype magnetic shielding system, including a nearly-hermetic superconducting lead shield, built to demonstrate the required gradients at 1/3-scale of the final experiment. Additionally, the system will evaluate the eddy current heating due to RF fields produced by a proposed neutron-``spin-dressing'' technique.

  19. 1999 Review of superconducting dipole and quadrupole magnets for particle accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Devred, A. [CEA/Saclay, Dept. d' Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l' Instrumentation Associee (DAPNIA), 91 - Gif-sur-Yvette (France); CERN, Conseil Europeen pour la recherche nucleaire, Laboratoire europeen pour la physique des particules Geneve (Switzerland)

    1999-12-01

    The quest for elementary particles has promoted the development of particle accelerators producing beams of increasingly higher energies. In a synchrotron-type accelerator, the particle energy is directly proportional to the product of the machine's radius times the bending magnets' field strength. Present proton experiments at the TeV scale require facilities with circumferences ranging from a few to tens of kilometers and relying on a large number (several hundreds to several thousands) of high field dipole magnets and high field gradient quadrupole magnets. These electro-magnets use high current density, low critical temperature superconducting cables and are cooled down at liquid helium temperature. They are among the most costly and the most challenging components of the machine. After explaining what are the various types of accelerator magnets and why they are needed (section 1), we present a brief history of large superconducting particle accelerators, and we detail ongoing superconducting accelerator magnet R and D programs around the world (Section 2). Then, we review the superconducting materials that are available at industrial scale (chiefly, NbTi and Nb3Sn), and we describe the manufacturing of NbTi wires and cables (section 3). We also present the difficulties of processing and insulating Nb3Sn conductors which, so far, have limited the use of this material in spite of its superior performances. We continue by presenting the complex formalism used to represent two-dimensional fields (section 4), and we discuss the two-dimensional current distributions that are the most appropriate for generating pure dipole and pure quadrupole fields (section 5). We explain how these ideal distributions can be approximated by so-called cos{theta} and cos{sup 2}{theta} coil designs and we describe the difficulties of realizing coil ends. Next, we present the mechanical design concepts that have been developed to restrain magnet coils and to ensure proper

  20. Operador dipolo-dipolo na base de momento angular: um complemento ao estudo de ressonância magnética nuclear Dipole-dipole operator in angular momentum basis: a complementary study in nuclear magnetic resonance

    Directory of Open Access Journals (Sweden)

    Rita de Cássia de Oliveira Sebastião

    2008-01-01

    Full Text Available The relationship between the magnetic dipole-dipole potential energy function and its quantum analogue is presented in this work. It is assumed the reader is familiar with the classical expression of the dipolar interaction and has basic knowledge of the quantum mechanics of angular momentum. Except for these two points only elementary steps are involved.

  1. Nature of Electric and Magnetic Dipoles Gleaned from the Poynting Theorem and the Lorentz Force Law of Classical Electrodynamics

    CERN Document Server

    Mansuripur, Masud

    2012-01-01

    Starting with the most general form of Maxwell's macroscopic equations in which the free charge and free current densities, rho_free and J_free, as well as the densities of polarization and magnetization, P and M, are arbitrary functions of space and time, we compare and contrast two versions of the Poynting vector, namely, S=ExB/mu_0 and S=ExH. Here E is the electric field, H the magnetic field, B the magnetic induction, and mu_0 the permeability of free space. We argue that the identification of one or the other of these Poynting vectors with the rate of flow of electromagnetic energy is intimately tied to the nature of magnetic dipoles and the way in which these dipoles exchange energy with the electromagnetic field. In addition, the manifest nature of both electric and magnetic dipoles in their interactions with the electromagnetic field has consequences for the Lorentz law of force. If the conventional identification of magnetic dipoles with Amperian current loops is extended beyond Maxwell's macroscopic...

  2. MULTIPLE FOCUSING OF ELECTROMAGNETIC FIELD OF MAGNETIC DIPOLE BY MEANS OF PLANE-PARALLEL TWO-LAYER LENS FROM METAMATERIALS

    Directory of Open Access Journals (Sweden)

    V. T. Erofeenko

    2016-01-01

    Full Text Available A method of analytical solution of the boundary-value problem of electromagnetic field penetration of point magnetic dipole through the infinite planar leans (screen from the focusing metamaterials is suggested. It is demonstrated, that for the lenses with special combinations of material parameters in layers the series of focuses are formed: one is over the screen and three is in front of the screen in the half-space of point source of the excitation field. The summary field of focuses in front of the lens is equal to the sum of fields of magnetic and electric dipoles.

  3. Anomalous magnetic and weak magnetic dipole moments of the τ lepton in the simplest little Higgs model

    Energy Technology Data Exchange (ETDEWEB)

    Arroyo-Urena, M.A.; Tavares-Velasco, G. [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias Fisico-Matematicas, Puebla, PUE (Mexico); Hernandez-Tome, G. [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias Fisico-Matematicas, Puebla, PUE (Mexico); Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional, Departamento de Fisica, Mexico City (Mexico)

    2017-04-15

    We obtain analytical expressions, both in terms of parametric integrals and Passarino-Veltman scalar functions, for the one-loop contributions to the anomalous weak magnetic dipole moment (AWMDM) of a charged lepton in the framework of the simplest little Higgs model (SLHM). Our results are general and can be useful to compute the weak properties of a charged lepton in other extensions of the standard model (SM). As a by-product we obtain generic contributions to the anomalous magnetic dipole moment (AMDM), which agree with previous results. We then study numerically the potential contributions from this model to the τ lepton AMDM and AWMDM for values of the parameter space consistent with current experimental data. It is found that they depend mainly on the energy scale f at which the global symmetry is broken and the t{sub β} parameter, whereas there is little sensitivity to a mild change in the values of other parameters of the model. While the τ AMDM is of the order of 10{sup -9}, the real (imaginary) part of its AWMDM is of the order of 10{sup -9} (10{sup -10}). These values seem to be out of the reach of the expected experimental sensitivity of future experiments. (orig.)

  4. Characterization of Nb3Sn Rutherford cables for the LHC 11-T Dipole Magnet

    CERN Document Server

    Wuis, A J; Ballarino, A; Oberli, L; Ten Kate, H H J

    2013-01-01

    The so-called CERN-LHC DS upgrade relies on the use of 11 T dipole magnets. For these magnets 40 strands Nb3Sn type Rutherford cables based on 0.7 mm wires are being developed. Recently four samples of the cables were characterized in the CERN FRESCA cable test station. The critical current and the premature quench current due to magneto-thermal instability were measured at 1.9 K and 4.3 K in a background magnetic field between 0 and 9.6 T (the peak magnetic field on the conductor, including the self-field of the cable, ranges from ~ 2 T to ~ 12 T). Two cable samples were based on Powder-In-Tube (PIT) wire and two on Restacked-Rod-Process (RRP) wire. The PIT samples were identical and without a core in the cable while one of the RRP samples features a 25 μm thick stainless steel core. All cables samples tested have a width and a thickness of about 14.7 mm and 1.25 mm, respectively. Cables and sample holders were manufactured at CERN. In this paper we report and discuss the cable test results and compare them...

  5. Magnetohydrodynamic Simulations of Hypersonic Flow over a Cylinder Using Axial- and Transverse-Oriented Magnetic Dipoles

    Directory of Open Access Journals (Sweden)

    Andrew N. Guarendi

    2013-01-01

    Full Text Available Numerical simulations of magnetohydrodynamic (MHD hypersonic flow over a cylinder are presented for axial- and transverse-oriented dipoles with different strengths. ANSYS CFX is used to carry out calculations for steady, laminar flows at a Mach number of 6.1, with a model for electrical conductivity as a function of temperature and pressure. The low magnetic Reynolds number (≪1 calculated based on the velocity and length scales in this problem justifies the quasistatic approximation, which assumes negligible effect of velocity on magnetic fields. Therefore, the governing equations employed in the simulations are the compressible Navier-Stokes and the energy equations with MHD-related source terms such as Lorentz force and Joule dissipation. The results demonstrate the ability of the magnetic field to affect the flowfield around the cylinder, which results in an increase in shock stand-off distance and reduction in overall temperature. Also, it is observed that there is a noticeable decrease in drag with the addition of the magnetic field.

  6. Magnetohydrodynamic simulations of hypersonic flow over a cylinder using axial- and transverse-oriented magnetic dipoles.

    Science.gov (United States)

    Guarendi, Andrew N; Chandy, Abhilash J

    2013-01-01

    Numerical simulations of magnetohydrodynamic (MHD) hypersonic flow over a cylinder are presented for axial- and transverse-oriented dipoles with different strengths. ANSYS CFX is used to carry out calculations for steady, laminar flows at a Mach number of 6.1, with a model for electrical conductivity as a function of temperature and pressure. The low magnetic Reynolds number (<1) calculated based on the velocity and length scales in this problem justifies the quasistatic approximation, which assumes negligible effect of velocity on magnetic fields. Therefore, the governing equations employed in the simulations are the compressible Navier-Stokes and the energy equations with MHD-related source terms such as Lorentz force and Joule dissipation. The results demonstrate the ability of the magnetic field to affect the flowfield around the cylinder, which results in an increase in shock stand-off distance and reduction in overall temperature. Also, it is observed that there is a noticeable decrease in drag with the addition of the magnetic field.

  7. Spherically restricted motion of a charge in the field of a magnetic dipole

    CERN Document Server

    Cortés, Emilio

    2013-01-01

    We study the restricted motion of an electric charge in a spherical surface in the field of a magnetic dipole. This is the classical non-relativistic St\\"oermer problem within a sphere, with the dipole in its centre. We start from a Lagrangian approach which allows us to analyze the dynamical properties of the system, such as the role of a velocity dependent potential, the symmetries and the conservation properties. We derive the Hamilton equations of motion and observe that in this restricted case the equations can be reduced to a quadrature. From the Hamiltonian function we find for the polar angle an equivalent one-dimensional system of a particle in the presence of an effective potential. This equivalent potential function, which is a double well potential, allows us to get a clear description of this dynamical problem. We are able to find closed horizontal trajectories, as well as their period. Depending on initial conditions, we can find also some bands covered by non-periodic trajectories, as well as t...

  8. Magnetic-dipole transitions in highly charged ions as a basis of ultraprecise optical clocks.

    Science.gov (United States)

    Yudin, V I; Taichenachev, A V; Derevianko, A

    2014-12-05

    We evaluate the feasibility of using magnetic-dipole (M1) transitions in highly charged ions as a basis of an optical atomic clockwork of exceptional accuracy. We consider a range of possibilities, including M1 transitions between clock levels of the same fine-structure and hyperfine-structure manifolds. In highly charged ions these transitions lie in the optical part of the spectra and can be probed with lasers. The most direct advantage of our proposal comes from the low degeneracy of clock levels and the simplicity of atomic structure in combination with negligible quadrupolar shift. We demonstrate that such clocks can have projected fractional accuracies below the 10^{-20}-10^{-21} level for all common systematic effects, such as blackbody radiation, Zeeman, ac-Stark, and quadrupolar shifts.

  9. Similarity transformation approach for ferromagnetic mixed convection flow in the presence of chemically reactive magnetic dipole

    Science.gov (United States)

    Hayat, Tasawar; Ijaz Khan, Muhammad; Imtiaz, Maria; Alsaedi, Ahmed; Waqas, Muhammad

    2016-10-01

    A simple model of chemical reactions for two dimensional ferrofluid flows is constructed. The impact of magnetic dipole and mixed convection is further analyzed. Flow is caused by linear stretching of the sheet. Similarity transformation is adopted to convert the partial differential equations into ordinary differential equations and then solved by Euler's explicit method. The characteristics of sundry parameters on the velocity, temperature, and concentration fields are graphically elaborated. It is noted that the impact of magneto-thermomechanical interaction is to slow down the fluid motion. The skin friction coefficient enhances and affects the rate of heat transfer. For higher values of ferrohydrodynamics, the interaction velocity shows decreasing behavior. Further the Prandtl number on temperature has opposite behavior when compared with thermal radiation and ferrohydrodynamics interaction.

  10. Mass and magnetic dipole moment of negative-parity heavy baryons with spin-3/2

    Science.gov (United States)

    Azizi, K.; Sundu, H.

    2017-01-01

    We calculate the mass and residue of the heavy spin-3/2 negative-parity baryons with single heavy bottom or charm quark by use of a two-point correlation function. We use the obtained results to investigate the diagonal radiative transitions among the baryons under consideration. In particular, we compute corresponding transition form factors via light cone QCD sum rules, which are then used to obtain the magnetic dipole moments of the heavy spin-3/2 negative-parity baryons. We remove the pollutions coming from the positive-parity spin-3/2 and positive/negative-parity spin-1/2 baryons by constructing sum rules for different Lorentz structures. We compare the results obtained with the existing theoretical predictions.

  11. Collaborative Simulation and Testing of the Superconducting Dipole Prototype Magnet for the FAIR Project

    Institute of Scientific and Technical Information of China (English)

    ZHU Yinfeng; ZHU Zhe; XU Houchang; WU Weiyue

    2012-01-01

    The superconducting dipole prototype magnet of the collector ring for the Facility for Antiproton and Ion Research (FAIR) is an international cooperation project. The collaborative simulation and testing of the developed prototype magnet is presented in this paper. To evaluate the mechanical strength of the coil case during quench, a 3-dimensional (3D) electromagnetic (EM) model was developed based on the solid97 magnetic vector element in the ANSYS commercial software, which includes the air region, coil and yoke. EM analysis was carried out with a peak operating current at 278 A. Then, the solid97 element was transferred into the solid185 element, the coupled analysis was switched from electromagnetic to structural, and the finite element model for the coil case and glass-fiber reinforced composite (G10) spacers was established by the ANSYS Parametric Design Language based on the 3D model from the CATIA V5 software. However, to simulate the friction characteristics inside the coil case, the conta173 surface-to-surface contact element was established. The results for the coil case and G10 spacers show that they are safe and have sufficient strength, on the basis of testing in discharge and quench scenarios.

  12. NMR absolute shielding scale and nuclear magnetic dipole moment of (207)Pb.

    Science.gov (United States)

    Adrjan, Bożena; Makulski, Włodzimierz; Jackowski, Karol; Demissie, Taye B; Ruud, Kenneth; Antušek, Andrej; Jaszuński, Michał

    2016-06-28

    An absolute shielding scale is proposed for (207)Pb nuclear magnetic resonance (NMR) spectroscopy. It is based on ab initio calculations performed on an isolated tetramethyllead Pb(CH3)4 molecule and the assignment of the experimental resonance frequency from the gas-phase NMR spectra of Pb(CH3)4, extrapolated to zero density of the buffer gas to obtain the result for an isolated molecule. The computed (207)Pb shielding constant is 10 790 ppm for the isolated molecule, leading to a shielding of 10799.7 ppm for liquid Pb(CH3)4 which is the accepted reference standard for (207)Pb NMR spectra. The new experimental and theoretical data are used to determine μ((207)Pb), the nuclear magnetic dipole moment of (207)Pb, by applying the standard relationship between NMR frequencies, shielding constants and nuclear moments of two nuclei in the same external magnetic field. Using the gas-phase (207)Pb and (reference) proton results and the theoretical value of the Pb shielding in Pb(CH3)4, we find μ((207)Pb) = 0.59064 μN. The analysis of new experimental and theoretical data obtained for the Pb(2+) ion in water solutions provides similar values of μ((207)Pb), in the range of 0.59000-0.59131 μN.

  13. Collaborative Simulation and Testing of the Superconducting Dipole Prototype Magnet for the FAIR Project

    Science.gov (United States)

    Zhu, Yinfeng; Zhu, Zhe; Xu, Houchang; Wu, Weiyue

    2012-08-01

    The superconducting dipole prototype magnet of the collector ring for the Facility for Antiproton and Ion Research (FAIR) is an international cooperation project. The collaborative simulation and testing of the developed prototype magnet is presented in this paper. To evaluate the mechanical strength of the coil case during quench, a 3-dimensional (3D) electromagnetic (EM) model was developed based on the solid97 magnetic vector element in the ANSYS commercial software, which includes the air region, coil and yoke. EM analysis was carried out with a peak operating current at 278 A. Then, the solid97 element was transferred into the solid185 element, the coupled analysis was switched from electromagnetic to structural, and the finite element model for the coil case and glass-fiber reinforced composite (G10) spacers was established by the ANSYS Parametric Design Language based on the 3D model from the CATIA V5 software. However, to simulate the friction characteristics inside the coil case, the conta173 surface-to-surface contact element was established. The results for the coil case and G10 spacers show that they are safe and have sufficient strength, on the basis of testing in discharge and quench scenarios.

  14. Formation of binary millisecond pulsars with relatively high surface dipole magnetic fields

    CERN Document Server

    Sutantyo, W

    2000-01-01

    We have carried out numerical evolutionary calculations of binary systems to investigate the formation of binary millisecond pulsars (pulsars with white dwarf companions). We apply the ``standard scenario'' in which the binary pulsars are formed from low-mass and intermediate-mass X-ray binaries as well the alternative scenario in which the neutron stars are formed by accretion-induced collapse (AIC) of white dwarfs. The mass transfer processes are carefully followed by taking into account a number of binary interactions. Assuming that the magnetic fields of the neutron stars decay due to the accretion, we calculate the pulsar surface dipole magnetic field strength at the end of the mass transfer as a function of the final orbital period. We find that while the observed data of the majority of pulsars are compatible with the derived relations, we fail to produce binary pulsars with relatively high magnetic fields and short orbital periods (such as PSR B0655+64). We conclude that those systems are most likely ...

  15. Fast electromagnetic modeling in cylindrically layered media excited by eccentred magnetic dipole

    Science.gov (United States)

    Nikitenko, Marina; Itskovich, Gregory B.; Seryakov, Alexander

    2016-06-01

    We developed a fast algorithm to calculate a response of cylindrically layered media excited by the vertical magnetic dipole eccentred with respect to the axis of symmetry. The algorithm calculates response in the range of frequencies typical for induction and dielectric logging. The media conductivity and dielectric constant are described by piecewise-constant functions. The corresponding boundary value problem is solved by method of separation of variables. Fourier transform is applied to Maxwell equations and boundary conditions to express field components through Fourier transforms of vertical components of an electrical and magnetic field. In addition, an expansion of vertical components into an infinite series with respect to angular harmonics is used to reduce the original problem to a series of 1-D problems that only depend on the radial coordinate. The solution to each 1-D radial problem for the angular harmonics is presented as a linear combination of modified Bessel functions. Finally, inverse Fourier transformation is applied to the angular harmonics of vertical components to derive electrical and magnetic field of the original boundary value problem. We provide detailed discussion on the elements that are critical for the numerical implementation of the algorithm: a proper normalization, convergence, and integration. Specifically, we show how to perform integration in the complex plane by avoiding intersection of the integration pass with the cuts located on the Riemann surface. Numerical results show the usefulness of the algorithm for solving inverse problems and for studying the effect of eccentricity in induction and dielectric logging.

  16. Torsional Oscillations of Relativistic Stars with Dipole Magnetic Fields II. Global Alfv\\'en Modes

    CERN Document Server

    Sotani, H; Stergioulas, N; Vavoulidis, M

    2006-01-01

    We investigate torsional Alfv\\'{e}n modes of relativistic stars with a global dipole magnetic field. It has been noted recently (Glampedakis et al. 2006) that such oscillation modes could serve as as an alternative explanation (in contrast to torsional crustal modes) for the SGR phenomenon, if the magnetic field is not confined to the crust. We compute global Alfv\\'{e}n modes for a representative sample of equations of state and magnetar masses, in the ideal MHD approximation and ignoring $\\ell \\pm 2$ terms in the eigenfunction. We find that the presence of a realistic crust has a negligible effect on Alfv\\'{e}n modes for $B > 4\\times 10^{15}$ G. Furthermore, we find strong avoided crossings between torsional Alfv\\'{e}n modes and torsional crust modes. For magnetar-like magnetic field strengths, the spacing between consecutive Alfv\\'{e}n modes is of the same order as the gap of avoided crossings. As a result, it is not possible to identify modes of predominantly crustal character and all oscillations are pred...

  17. Magnetic dipole properties in the SU(3) limit of IBA-2 with L=0, 2 and 4 bosons

    NARCIS (Netherlands)

    Wu, H.C.; Dieperink, A. E. L.; Scholten, O.

    1987-01-01

    Properties of the magnetic dipole operator in the neutron-proton IBA model with L = 0, 2 and 4 bosons are discussed. Analytic expressions are derived for M1 matrix elements for low-lying states in the SU(3) limit.

  18. The gravitational force on a gyroscope and the electromagnetic force on a magnetic dipole as analogous tidal effects

    Energy Technology Data Exchange (ETDEWEB)

    Costa, L Filipe O; Herdeiro, Carlos A R, E-mail: filipezola@fc.up.p, E-mail: crherdei@fc.up.p [Centro de Fisica do Porto, Faculdade de Ciencias Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal)

    2010-05-01

    We compare the covariant expression of the electromagnetic force exerted on a magnetic dipole with Papapetrou's equation for the gravitational force exerted on a spinning test particle. We show that if Pirani's supplementary spin condition holds, there is an exact, covariant, and fully general analogy relating these two forces: both are determined by a contraction of the spin 4-vector with a magnetic-type tidal tensor. Moreover, these tidal tensors obey strikingly analogous equations which are covariant forms for (some of) Maxwell's and Einstein's field equations. These equations allow for an insightful comparison between the two interactions. It is shown that, in the special case that the gyroscope/dipole are 'at rest' and far away from a stationary source, the two forces are similar (in accordance with the results known from linearized theory); but that for generic dynamics key differences arise. In particular we show that the time projection of the force on a dipole is the power transferred to it by Faraday's induction, whereas the fact that the force on a gyroscope is spatial signals the absence of an analogous gravitational effect; that whereas the total work done on a magnetic dipole by a stationary magnetic field is zero, a stationary gravitomagnetic field, by contrast, does work on mass currents, which quantitatively explains the Hawking-Wald spin interaction energy.

  19. Accessing interior magnetic field vector components in neutron electric dipole moment experiments via exterior measurements, I. Boundary-value techniques

    CERN Document Server

    Plaster, B

    2013-01-01

    We propose a new concept for determining the interior magnetic field vector components in neutron electric dipole moment experiments. If a closed three-dimensional boundary surface surrounding the fiducial volume of an experiment can be defined such that its interior encloses no currents or sources of magnetization, each of the interior vector field components and the magnetic scalar potential will satisfy a Laplace equation. Therefore, if either the vector field components or the normal derivative of the scalar potential can be measured on the surface of this boundary, thus defining a Dirichlet or Neumann boundary-value problem, respectively, the interior vector field components or the scalar potential (and, thus, the field components via the gradient of the potential) can be uniquely determined via solution of the Laplace equation. We discuss the applicability of this technique to the determination of the interior magnetic field components during the operating phase of neutron electric dipole moment experim...

  20. Conductor related design considerations for a 1 meter 10 T NB/sub 3/Sn dipole magnet

    NARCIS (Netherlands)

    Ouden, den A.; Wessel, W.A.J.; Krooshoop, H.J.G.; Weeren, van H.; Kate, ten H.H.J.; Kirby, G.A.; Ostojic, R.; Taylor, T.; Siegel, N.

    2003-01-01

    A single-bore 1 meter long 10 T Nb/sub 3/Sn dipole magnet with a 88 mm bore is being developed. Based on powder-in-tube (PIT) Nb/sub 3/Sn strands exhibiting 22 /spl mu/m thick filaments, a Rutherford-type cable with a stainless steel core of 25 micron is employed. All properties relevant for magnet

  1. Reaching the Chu Lower Bound on Q With Magnetic Dipole Antennas Using a Magnetic-Coated PEC Core

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Breinbjerg, Olav

    2011-01-01

    We analytically solve the radiation problem for a spherical magnetic dipole antenna with a material-coated perfectly electrically conducting core. Using the closed-form expressions derived for the internal and external stored energies as well as for the radiation quality factor $Q$, we determine...... the optimal geometrical and material parameters of the antenna. We show that the optimal permeability of the coating increases as the coating becomes thinner; as a result, the energy stored in it and the radiation quality factor $Q$ reduce. In the limit of an infinitely thin coating, the optimal permeability...... tends to infinity, the internal stored energy vanishes, and the $Q$ reaches the Chu lower bound, irrespective of the antenna electrical size $ka$ and permittivity of the coating....

  2. Constraining C P T -even and Lorentz-violating nonminimal couplings with the electron magnetic and electric dipole moments

    Science.gov (United States)

    Araujo, Jonas B.; Casana, Rodolfo; Ferreira, Manoel M.

    2015-07-01

    We analyze some dimension-five C P T -even and Lorentz-violating nonminimal couplings between fermionic and gauge fields in the context of the Dirac equation. After evaluating the nonrelativistic Hamiltonian, we discuss the behavior of the terms under discrete symmetries and analyze the implied effects. We then use the anomalous magnetic dipole moment and electron electric dipole moment measurements to reach upper bounds of 1 part in 1020 and 1024 (eV )-1 , improving the level of restriction on such couplings by at least 8 orders of magnitude. These upper bounds are also transferred to the Sun-centered frame by considering the Earth's rotational motion.

  3. The effect of an offset-dipole magnetic field on the Vela pulsar's gamma-ray light curves

    CERN Document Server

    Breed, M; Harding, A K; Johnson, T J

    2015-01-01

    Over the past six years, the Fermi Large Area Telescope has detected more than 150 gamma-ray pulsars, discovering a variety of light curve trends and classes. Such diversity hints at distinct underlying magnetospheric and/or emission geometries. We implemented an offset-dipole magnetic field, with an offset characterised by parameters epsilon and magnetic azimuthal angle, in an existing geometric pulsar modelling code which already includes static and retarded vacuum dipole fields. We use these different magnetic field solutions in conjunction with standard emission geometries, namely the two-pole caustic and outer gap models (the latter only for non-offset dipoles), and construct intensity maps and light curves for several pulsar parameters. We compare our model light curves to the Vela data from the second pulsar catalogue of Fermi. We use a refined chi-square grid search method for finding best-fit light curves for each of the different models. Our best fit is for the retarded vacuum dipole field and the o...

  4. Magnetic Dipole Inflation with Cascaded ARC and Applications to Mini-Magnetospheric Plasma Propulsion

    Science.gov (United States)

    Giersch, L.; Winglee, R.; Slough, J.; Ziemba, T.; Euripides, P.

    2003-01-01

    Mini-Magnetospheric Plasma Propulsion (M2P2) seeks to create a plasma-inflated magnetic bubble capable of intercepting significant thrust from the solar wind for the purposes of high speed, high efficiency spacecraft propulsion. Previous laboratory experiments into the M2P2 concept have primarily used helicon plasma sources to inflate the dipole magnetic field. The work presented here uses an alternative plasma source, the cascaded arc, in a geometry similar to that used in previous helicon experiments. Time resolved measurements of the equatorial plasma density have been conducted and the results are discussed. The equatorial plasma density transitions from an initially asymmetric configuration early in the shot to a quasisymmetric configuration during plasma production, and then returns to an asymmetric configuration when the source is shut off. The exact reasons for these changes in configuration are unknown, but convection of the loaded flux tube is suspected. The diffusion time was found to be an order of magnitude longer than the Bohm diffusion time for the period of time after the plasma source was shut off. The data collected indicate the plasma has an electron temperature of approximately 11 eV, an order of magnitude hotter than plasmas generated by cascaded arcs operating under different conditions. In addition, indirect evidence suggests that the plasma has a beta of order unity in the source region.

  5. Measurement of Magnetic Field Uniformity For a Neutron Electric Dipole Moment Detector with New Lead Endcaps

    Science.gov (United States)

    Kulkarni, Anita; Filippone, Bradley; Slutsky, Simon; Swank, Christopher; Carr, Robert; Osthelder, Charles; Biswas, Aritra; Molina, Daniel

    2016-09-01

    Over the last several decades, physicists have been measuring the neutron electric dipole moment (nEDM) with greater and greater sensitivity. The latest experiment we are developing will have 100 times more sensitivity than the previous leading experiment. A nonzero nEDM could, among other consequences, explain the presence of more matter than antimatter in the universe. To measure the nEDM with high accuracy, it is necessary to have a very uniform magnetic field inside the detector since non-uniformities can create false signals via the geometric phase effect. One way to improve field uniformity is to add superconducting lead endcaps to the detector, which constrain the fields at their surfaces to be parallel to them. Here, we test how the endcaps improve field uniformity by measuring the magnetic field at various points in a 1/3-scale experimental volume, inferring what the field must be at all other points, and calculating gradients in the field. This knowledge could help guide further steps needed to improve field uniformity and characterize limitations to the sensitivity of nEDM measurements for the full-scale experiment. Rose Hills Foundation, National Science Foundation Grant 1506459, and Department of Energy.

  6. Cryogenics for the CERN Solar Axion Telescope (CAST) using a LHC Dipole Prototype Magnet

    CERN Document Server

    Barth, K; Pezzetti, M; Pirotte, O; Riege, H; Vullierme, B; Walckiers, L; Zioutas, Konstantin

    2002-01-01

    The axion, an as yet hypothetical particle predicted from the solution of the strong CP problem, constitutes a prime candidate for the galactic dark matter and also arises in supersymmetry and superstring theories. If existing, axions should be copiously produced in stellar interiors and there are theoretical expectations for a low-energy axion emission spectrum peaked around a mean energy of ~ 4.4 keV. To provide the experimental proof, a solar axion telescope is at present installed at CERN, which is expected to be in total 10-12 times more efficient than the present largest set-up in operation at the University of Tokyo. The telescope will use a decommissioned 10-m long LHC superconducting dipole prototype magnet, providing a magnetic field of 9 T in operation, to catalyse the solar axion to photon conversion, which then can be detected by low-background x-ray detectors. The paper describes the external and proximity cryogenic systems and their integration into the overall telescope assembly.

  7. LHC main dipole magnet circuits: sustaining near-nominal beam energies

    CERN Document Server

    AUTHOR|(CDS)2085621; Auchmann, Bernhard; Knox, Andrew; O'Shea, Valentine

    2016-11-04

    Crossing the Franco-Swiss border, the Large Hadron Collider (LHC), designed to collide 7 TeV proton beams, is the world's largest and most powerful particle accelerator the operation of which was originally intended to commence in 2008. Unfortunately, due to an interconnect discontinuity in one of the main dipole circuit's 13 kA superconducting busbars, a catastrophic quench event occurred during initial magnet training, causing significant physical system damage. Furthermore, investigation into the cause found that such discontinuities were not only present in the circuit in question, but throughout the entire LHC. This prevented further magnet training and ultimately resulted in the maximum sustainable beam energy being limited to approximately half that of the design nominal, 3.5-4 TeV, for the first three years of operation (Run 1, 2009-2012) and a major consolidation campaign being scheduled for the first long shutdown (LS 1, 2012-2014). Throughout Run 1, a series of studies attempted to predict the amo...

  8. A New Method for Modeling the Coronal Magnetic Field with STEREO and Submerged Dipoles

    Science.gov (United States)

    Sandman, A. W.; Aschwanden, M. J.

    2011-06-01

    Recent magnetic modeling efforts have shown substantial misalignment between theoretical models and observed coronal loop morphology as observed by STEREO/EUVI, regardless of the type of model used. Both potential field and non-linear force-free field (NLFFF) models yielded overall misalignment angles of 20 - 40 degrees, depending on the complexity of the active region (Sandman et al., Solar Phys. 259, 1, 2009; DeRosa et al., Astrophys. J. 696, 1780, 2009) We demonstrate that with new, alternative forward-fitting techniques, we can achieve a significant reduction in the misalignment angles compared with potential field source surface (PFSS) models and NLFFF models. Fitting a series of submerged dipoles to the field directions of stereoscopically triangulated loops in four active regions (30 April, 9 May, 19 May, and 11 December 2007), we find that 3 - 5 dipoles per active region yield misalignment angles of ˜ 11° - 18°, a factor of two smaller than those given by previously established extrapolation methods. We investigate the spatial and temporal variation of misalignment angles with subsets of loops for each active region, as well as loops observed prior to and following a flare and filament eruption, and find that the spatial variation of median misalignment angles within an active region (up to 75%) exceeds the temporal variation associated with the flare (up to 40%). We also examine estimates of the stereoscopic error of our analysis. The corrected values yield a residual misalignment of 7° - 13°, which is attributed to the non-potentiality due to currents in the active regions.

  9. Wave propagation in a moving cold magnetized plasma

    Science.gov (United States)

    Hebenstreit, H.

    1980-03-01

    Polarization relations and dispersion equations are derived for media that are electrically anisotropic in the comoving frame. Three-dimensional calculations for media at rest recover the known dispersion equations, i.e., Astrom's dispersion equation for magnetized cold plasmas and Fresnel's wave normal equation for uniaxial crystals. An analogous four-dimensional calculation yields the generalization to moving media. The dispersion equations so obtained for moving gyrotropic media are then discussed qualitatively for various special media and special directions of wave propagation. Finally, the polarization relations are specialized to media gyrotropic in the comoving frame.

  10. Measurement of homonuclear magnetic dipole-dipole interactions in multiple 1/2-spin systems using constant-time DQ-DRENAR NMR.

    Science.gov (United States)

    Ren, Jinjun; Eckert, Hellmut

    2015-11-01

    A new pulse sequence entitled DQ-DRENAR (Double-Quantum based Dipolar Recoupling Effects Nuclear Alignment Reduction) was recently described for the quantitative measurement of magnetic dipole-dipole interactions in homonuclear spin-1/2 systems involving multiple nuclei. As described in the present manuscript, the efficiency and performance of this sequence can be significantly improved, if the measurement is done in the constant-time mode. We describe both the theoretical analysis of this method and its experimental validation of a number of crystalline model compounds, considering both symmetry-based and back-to-back (BABA) DQ-coherence excitation schemes. Based on the combination of theoretical analysis and experimental results we discuss the effect of experimental parameters such as the chemical shift anisotropy (CSA), the spinning rate, and the radio frequency field inhomogeneity upon its performance. Our results indicate that constant-time (CT-) DRENAR is a method of high efficiency and accuracy for compounds with multiple homonuclear spin systems with particular promise for the analysis of stronger-coupled and short T2 spin systems.

  11. Production of Low-Carbon Magnetic Steel for the LHC Superconducting Dipole and Quadrupole Magnets

    CERN Document Server

    Bertinelli, F; Harlet, P; Peiro, G; Russo, A; Taquet, A

    2006-01-01

    In 1996 CERN negotiated a contract with Cockerill Sambre – ARCELOR Group for the supply of 50 000 tonnes of low-carbon steel for the LHC main magnets: this was the first contract to be placed for the project, and one of the single largest. In 2005 – after nine years of work – the contract is being successfully completed. This paper describes the steel specifically developed, known as MAGNETIL™, its manufacturing and quality control process, organization of production, logistics and contract follow-up. Extensive statistics have been collected relating to physical, mechanical and technological parameters. Specific attention is dedicated to magnetic measurements (coercivity and permeability) performed at both room and cryogenic temperatures, the equipment used and statistical results. Reference is also made to the resulting precision of the fineblanked laminations used for the magnet yoke. The technology transfer from the particle accelerator domain to industry is ongoing, for example for ...

  12. Magnetopause energy transfer dependence on the interplanetary magnetic field and the Earth's magnetic dipole axis orientation

    Directory of Open Access Journals (Sweden)

    M. Palmroth

    2012-03-01

    Full Text Available We examine the spatial variation of magnetospheric energy transfer using a global magnetohydrodynamic (MHD simulation (GUMICS-4 and a large data set of flux transfer events (FTEs observed by the Cluster spacecraft. Our main purpose is to investigate whether it is possible to validate previous results on the spatial energy transfer variation from the GUMICS-4 simulation using the statistical occurrence of FTEs, which are manifestations of magnetospheric energy transfer. Previous simulation results have suggested that the energy transfer pattern at the magnetopause rotates according to the interplanetary magnetic field (IMF orientation, and here we investigate whether a similar rotation is seen in the locations at which FTE signatures are observed. We find that there is qualitative agreement between the simulation and observed statistics, as the peaks in both distributions rotate as a function of the IMF clock angle. However, it is necessary to take into account the modulation of the statistical distribution that is caused by a bias towards in situ FTE signatures being observed in the winter hemisphere (an effect that has previously been predicted and observed in this data set. Taking this seasonal effect into account, the FTE locations support the previous simulation results and confirm the earlier prediction that the energy transfers in the plane of the IMF. In addition, we investigate the effect of the dipole orientation (both the dipole tilt angle and its orientation in the plane perpendicular to the solar wind flow on the energy transfer spatial distribution. We find that the energy transfer occurs mainly in the summer hemisphere, and that the dayside reconnection region is located asymmetrically about the subsolar position. Finally, we find that the energy transfer is 10% larger at equinox conditions than at solstice, contributing to the discussion concerning the semiannual variation of magnetospheric dynamics (known as "the Russell

  13. R&D steps of a 12-T common coil dipole magnet for SPPC pre-study

    Science.gov (United States)

    Wang, Chengtao; Zhang, Kai; Xu, Qingjin

    2016-11-01

    IHEP (the Institute of High Energy Physics, Beijing, China) has started the R&D of high field accelerator magnet technology from 2014 for recently proposed CEPC-SppC (Circular Electron Positron Collider, Super proton-proton Collider) project. The conceptual design study of a 20-T dipole magnet is ongoing with the common coil configuration, and a 12-T model magnet will be fabricated in the next two years. A 3-step R&D process has been proposed to realize this 12-T common-coil model magnet: first, a 12-T subscale magnet will be fabricated with Nb3Sn and NbTi superconductors to investigate the fabrication process and characteristics of Nb3Sn coils, then a 12-T subscale magnet will be fabricated with only Nb3Sn superconductors to test the stress management method and quench protection method of Nb3Sn coils; the final step is fabricating the 12-T common-coil dipole magnet with HTS (YBCO) and Nb3Sn superconductors to test the field optimization method of the HTS and Nb3Sn coils. The characteristics of these R&D steps will be introduced in the paper.

  14. Solder-Filling of a Cicc Cable for the Efda Dipole Magnet

    Science.gov (United States)

    Bauer, P.; Bruzzone, P.; Cau, F.; Weiss, K.; Portone, A.; Salpietro, E.; Vogel, M.; Vostner, A.

    2008-03-01

    Several prototype Cable-In-Conduit-Conductors (CICC) for the superconducting EDIPO (Efda DIPOle) revealed a degradation of their critical current (Ic) increasing with each loading cycle. The strong Lorentz-forces during operation in combination with the limited support of the single strands against these forces are thought to be the cause of the permanent degradation of the brittle Nb3Sn superconductor from which the multi-stranded CICC are made. In summer 2006 EFDA started to explore the possibility to remedy the Ic degradation by solder-filling the conductor in order to mechanically stabilize the twisted-strand cable inside the conduit. This solution was not considered as the main one, but as an emergency solution to be applied to the completed magnet, should every other option fail. The solder-filling approach was previously applied with success in some cases. Some issues, however, needed to be clarified before this solution could be proposed for the EDIPO project. The most important among them are the choice of solder material, details of the solder filling process, and the thermo-mechanical implications of a solder-filled, high-field, high-current cable. This work, being reported here, made use not only of simulation but also of experiments, such as the mechanical testing of solder filled cables at cryogenic temperatures.

  15. Fabrication of Rutherford-type superconducting cables for construction of dipole magnets

    Energy Technology Data Exchange (ETDEWEB)

    Scanlan, R.M.; Royet, J.; Hannaford, R.

    1988-05-01

    An experimental cabling machine has been constructed and used to investigate the fabrication of a variety of superconducting cables. These include the 23-strand and 30-strand NbTi alloy cables for the Superconducting Supercollider (SSC) and a number of experimental cables. The experimental cables include 24-strands and 36-strands as well as two-level cables with a 6 or 7-strand first level and 23 or 30-strand second level. These results were used to aid in selecting the optimum cable for the SSC dipole and quadrupole magnets. As a result of these studies, cable can now be fabricated to exacting mechanical tolerances (+/- .006 mm) and with low critical current degradation (2-5%). In addition, tooling design studies have been performed and a Prototype SSC Production Cabling Machine has been designed. The results of the cable optimization studies and the tooling design studies will be discussed. SSC cable production experience on the experimental cabling machine and the production cabling machine will be reported.

  16. Analysis of the mechanical behaviour of a 11.5 T Nb3Sn LHC dipole magnet according to the ring collar concept

    NARCIS (Netherlands)

    Ouden, den A.; Kate, ten H.H.J.; Avest, ter D.; Emden, van W.; Daum, C.

    1992-01-01

    According to the CERN-LHC (Large Hadron Collider) reference design, 10-tesla twin-aperture NbTi dipoles will be built with split collars that enclose both apertures. As part of the development program towards an experimental 11.5-tesla Nb3Sn LHC dipole magnet, the mechanical implications of an alter

  17. Superdirective Magnetic Dipole Array as a First-Order Probe for Spherical Near-Field Antenna Measurements

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Pivnenko, Sergey; Breinbjerg, Olav

    2012-01-01

    The theory as well as numerical and experimental results are presented for a superdirective array composed of closely spaced electrically small resonant magnetic dipole elements. The array operates on a metal ground plane and can exhibit a maximum directivity of 11.5 dBi, 15.2 dBi, and 17.8 d......Bi (including 3 dB due to the ground plane), for 2, 3, and 4 magnetic dipoles, respectively. The array is self-resonant and is directly excited by a 50-ohm coaxial cable through the ground plane. The array radiates essentially the $\\vert\\mu\\vert=1$ spherical modes, which, despite a narrow bandwidth, makes...

  18. Evolution of calculations of the virtual dipole moment of the Earth for reconstructing the oceanic inversion magnetic layer's parameters

    Science.gov (United States)

    Schreider, A. A.; Ignatova, A. A.; Schreider, Al. A.; Sajneva, A. E.; Varga, P.; Denis, C.

    2016-05-01

    The VDM (virtual dipole moment) is one of the most significant characteristics describing the behavior of the time evolution of the terrestrial magnetic field. However, we have revealed that the formulas with which VDM calculations are performed often do not coincide with each other in various literature sources. Hence, results are obtained from these calculations that cannot be identical. Their correctness is verified by comparing the dimension and obtained results with the known value of the VDM for our time.

  19. General classical and quantum-mechanical description of magnetic resonance: an application to electric-dipole-moment experiments

    Energy Technology Data Exchange (ETDEWEB)

    Silenko, Alexander J. [Belarusian State University, Research Institute for Nuclear Problems, Minsk (Belarus); Joint Institute for Nuclear Research, Bogoliubov Laboratory of Theoretical Physics, Dubna (Russian Federation)

    2017-05-15

    A general theoretical description of a magnetic resonance is presented. This description is necessary for a detailed analysis of spin dynamics in electric-dipole-moment experiments in storage rings. General formulas describing a behavior of all components of the polarization vector at the magnetic resonance are obtained for an arbitrary initial polarization. These formulas are exact on condition that the nonresonance rotating field is neglected. The spin dynamics is also calculated at frequencies far from resonance with allowance for both rotating fields. A general quantum-mechanical analysis of the spin evolution at the magnetic resonance is fulfilled and the full agreement between the classical and quantum-mechanical approaches is shown. Quasimagnetic resonances for particles and nuclei moving in noncontinuous perturbing fields of accelerators and storage rings are considered. Distinguishing features of quasimagnetic resonances in storage ring electric-dipole-moment experiments are investigated in detail. The exact formulas for the effect caused by the electric dipole moment are derived. The difference between the resonance effects conditioned by the rf electric-field flipper and the rf Wien filter is found and is calculated for the first time. The existence of this difference is crucial for the establishment of a consent between analytical derivations and computer simulations and for checking spin tracking programs. The main systematical errors are considered. (orig.)

  20. Measurement of a false electric dipole moment signal from $^{199}$Hg atoms exposed to an inhomogeneous magnetic field

    CERN Document Server

    Afach, S; Ban, G; Bison, G; Bodek, K; Chowdhuri, Z; Daum, M; Fertl, M; Franke, B; Geltenbort, P; Green, K; van der Grinten, M G D; Grujic, Z; Harris, P G; Heil, W; Hélaine, V; Henneck, R; Horras, M; Iaydjiev, P; Ivanov, S N; Kasprzak, M; Kermaïdic, Y; Kirch, K; Knowles, P; Koch, H -C; Komposch, S; Kozela, A; Krempel, J; Lauss, B; Lefort, T; Lemière, Y; Mtchedlishvili, A; Naviliat-Cuncic, O; Pendlebury, J M; Piegsa, F M; Pignol, G; Prashant, P N; Quéméner, G; Rebreyend, D; Ries, D; Roccia, S; Schmidt-Wellenburg, P; Severijns, N; Weis, A; Wursten, E; Wyszynski, G; Zejma, J; Zenner, J; Zsigmond, G

    2015-01-01

    We report on the measurement of a Larmor frequency shift proportional to the electric-field strength for $^{199}{\\rm Hg}$ atoms contained in a volume permeated with aligned magnetic and electric fields. This shift arises from the interplay between the inevitable magnetic field gradients and the motional magnetic field. The proportionality to electric-field strength makes it apparently similar to an electric dipole moment (EDM) signal, although unlike an EDM this effect is P- and T-conserving. We have used a neutron magnetic resonance EDM spectrometer, featuring a mercury co-magnetometer and an array of external cesium magnetometers, to measure the shift as a function of the applied magnetic field gradient. Our results are in good agreement with theoretical expectations.

  1. Review- Numerical simulation of chainlike cluster movement of feeble magnetic particles by induced magnetic dipole moment under high magnetic fields

    Directory of Open Access Journals (Sweden)

    Tsutomu Ando, Noriyuki Hirota and Hitoshi Wada

    2009-01-01

    Full Text Available In this paper, the motion of a chainlike cluster of feeble magnetic particles induced by high magnetic field is discussed on the basis of the results of numerical simulations. The simulations were performed on glass particles with a diameter of 0.8 mm; and the viscosity, applied magnetic field and magnetic properties of the surrounding medium were changed. In addition to the magnetic field and the difference in magnetic susceptibility between the particles and the surrounding medium, the obtained results indicate that the viscosity is an essential factor for the formation of the chainlike alignment of feeble magnetic particles. We also carried out simulations using glass particles with a smaller diameter of 0.1 mm. Chainlike clusters were produced similar to those of ferromagnetic particles formed in a ferromagnetic fluid.

  2. Single-band and Dual-band Artificial Magnetic Conductor Ground Planes for Multi-band Dipole Antenna

    Directory of Open Access Journals (Sweden)

    M. Abu

    2012-12-01

    Full Text Available Two new designs of high impedance surface (HIS structure are presented, namely zigzag and slotted rectangular with I-shaped slot Artificial Magnetic Conductor (AMC. The zigzag AMC is designed based on the straight dipole AMC. The zigzag AMC is introduced to minimize the AMC size and to be suitable for UHF RFID applications. On the other hand, the slotted rectangular with I-shaped slot AMC is designed to operate at 0.92 GHz and 2.45 GHz. The slot is loaded in the main patch of the AMC to create the other resonant frequency. By using this technique the resonant frequency can be lowered, and hence reduce the size of the AMC. Both structures are designed using the same dielectric substrate that is Taconic TLC-32. The properties of the AMC are investigated such as the reflection phase, reflection magnitude and surface impedance. The designed AMCs then are used as a back plane for the printed multi-band dipole antenna. By introducing the AMC as a ground plane (GP for the printed dipole antenna, the gain of the dipole antenna is increased.

  3. Fen (n=1–6) clusters chemisorbed on vacancy defects in graphene: Stability, spin-dipole moment, and magnetic anisotropy

    KAUST Repository

    Haldar, Soumyajyoti

    2014-05-09

    In this work, we have studied the chemical and magnetic interactions of Fen (n=1–6) clusters with vacancy defects (monovacancy to correlated vacancies with six missing C atoms) in a graphene sheet by ab initio density functional calculations combined with Hubbard U corrections for correlated Fe-d electrons. It is found that the vacancy formation energies are lowered in the presence of Fe, indicating an easier destruction of the graphene sheet. Due to strong chemical interactions between Fe clusters and vacancies, a complex distribution of magnetic moments appear on the distorted Fe clusters which results in reduced averaged magnetic moments compared to the free clusters. In addition to that, we have calculated spin-dipole moments and magnetic anisotropy energies. The calculated spin-dipole moments arising from anisotropic spin density distributions vary between positive and negative values, yielding increased or decreased effective moments. Depending on the cluster geometry, the easy axis of magnetization of the Fe clusters shows in-plane or out-of-plane behavior.

  4. Experimental demonstration of acoustic wave induced magnetization switching in dipole coupled magnetostrictive nanomagnets for ultralow power computing

    Science.gov (United States)

    Sampath, Vimal; D'Souza, Noel; Atkinson, Gary M.; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

    2016-09-01

    Dipole-coupled cobalt nanomagnet pairs of elliptical shape (with their major axes parallel) are delineated on 128° Y-cut lithium niobate. Each pair is initially magnetized along the major axis with a magnetic field forming the (↑↑) state. When an acoustic wave (AW) is launched in the substrate from interdigitated electrodes, the softer nanomagnet in the pair flips to produce the (↑↓) state since the AW modulates the stress anisotropy. This executes the logical NOT operation because the output bit encoded in the magnetization state of the softer nanomagnet becomes the logic complement of the input bit encoded in the magnetization of the harder one. The AW acts as a clock to trigger the NOT operation and the energy dissipated is a few tens of aJ. Such AW clocking can be utilized to flip nanomagnets in a chain sequentially to steer logic bits unidirectionally along a nanomagnetic logic wire with miniscule energy dissipation.

  5. Frequency shifts in an optical lattice clock due to magnetic-dipole and electric-quadrupole transitions.

    Science.gov (United States)

    Taichenachev, A V; Yudin, V I; Ovsiannikov, V D; Pal'chikov, V G; Oates, C W

    2008-11-01

    We report a hitherto undiscovered frequency shift for forbidden J = 0-->J = 0 clock transitions excited in atoms confined to an optical lattice. These shifts result from magnetic-dipole and electric-quadrupole transitions, which have a spatial dependence in an optical lattice that differs from that of the stronger electric-dipole transitions. In combination with the residual translational motion of atoms in an optical lattice, this spatial mismatch leads to a frequency shift via differential energy level spacing in the lattice wells for ground state and excited state atoms. We estimate that this effect could lead to fractional frequency shifts as large as 10(-16), which might prevent lattice-based optical clocks from reaching their predicted performance levels. Moreover, these effects could shift the magic wavelength in lattice clocks in three dimensions by as much as 100 MHz, depending on the lattice configuration.

  6. Gain enhancement of low profile on-chip dipole antenna via Artificial Magnetic Conductor at 94 GHz

    KAUST Repository

    Nafe, Mahmoud

    2015-04-13

    The bottleneck for realizing high efficiency System-on-Chip is integrating the antenna on the lossy silicon substrate. To shield the antenna from the silicon, a ground plane can be used. However, the ultra-thin oxide does not provide enough separation between the antenna and the ground plane. In this work, we demonstrate one of the highest reported gains to date for low profile 94 GHz on-chip dipole antenna while the ground plane is in the lowest metal in the oxide (M1). This is achieved by optimizing an Artificial Magnetic Conductor (AMC) structure midway the antenna and M1. The dipole antenna without the AMC has a gain of − 11 dBi while with the AMC structure a gain of + 4.8 dBi and hence achieving a gain enhancement of + 15.8 dB.

  7. MRI detection of weak magnetic fields due to an extended current dipole in a conducting sphere: a model for direct detection of neuronal currents in the brain.

    Science.gov (United States)

    Konn, Daniel; Gowland, Penny; Bowtell, Richard

    2003-07-01

    To investigate the feasibility of direct MR detection of neuronal activity in the brain, neuronal current flow was modeled as an extended current dipole located in a conducting sphere. The spatially varying magnetic field induced within the sphere by such a dipole was calculated, including its form close to and within the current source. The predicted field variation was experimentally verified by measurements of the variation in phase of the MR signal in a sphere containing a model dipole. The effects of the calculated magnetic field distributions on the phase and magnitude of the signal in MR images were explored. The minimum detectable dipole strength under normal experimental conditions was calculated to be about 4.5 nAm, which is similar in magnitude to dipole strengths from evoked neuronal activity, and is an order of magnitude smaller than dipole strengths expected from spontaneous activity. This minimum detectable dipole strength increases with increasing spatial extent of the primary current distribution. In the experimental work, the effects of a field of [1.1 +/- 0.5] x 10(-10) T strength were detected, corresponding to the maximum net field caused by a dipole of 6.3 nAm strength with a spatial extent of 3 x 3 x 2 mm(3). Copyright 2003 Wiley-Liss, Inc.

  8. Weak magnetic fields in Ap/Bp stars: Evidence for a dipole field lower limit and a tentative interpretation of the magnetic dichotomy

    CERN Document Server

    Aurière, M; Silvester, J; Lignières, F; Bagnulo, S; Bale, K; Dintrans, B; Donati, J F; Folsom, C P; Gruberbauer, M; Hoa, A Hui Bon; Jeffers, S; Johnson, N; Landstreet, J D; Lebre, A; Lüftinger, T; Marsden, S; Mouillet, D; Naseri, S; Paletou, F; Petit, P; Power, J; Rincon, F; Strasser, S; Toque, N

    2007-01-01

    We have investigated a sample of 28 well-known spectroscopically-identified magnetic Ap/Bp stars, with weak, poorly-determined or previously undetected magnetic fields, with the aim of exploring the weak part of the magnetic field distribution of Ap/Bp stars. Using the MuSiCoS and NARVAL spectropolarimeters we have obtained 282 LSD Stokes V signatures of our 28 sample stars. All stars were detected, showing clearly that when observed with sufficient precision, all firmly classified Ap/Bp stars show detectable surface magnetic fields. To better characterise the surface magnetic field intensities and geometries of the sample, we have inferred the dipolar field intensity and the magnetic obliquity. The distribution of derived dipole strengths for these stars exhibits a plateau at about 1 kG, falling off to larger and smaller field strengths. Remarkably, in this sample of stars selected for their presumably weak magnetic fields, we find only 2 stars for which the derived dipole strength is weaker than 300 G. We i...

  9. Self-assembly of three-dimensional ensembles of magnetic particles with laterally shifted dipoles.

    Science.gov (United States)

    Yener, Arzu B; Klapp, Sabine H L

    2016-02-21

    We consider a model of colloidal spherical particles carrying a permanent dipole moment which is laterally shifted out of the particles' geometrical centres, i.e. the dipole vector is oriented perpendicular to the radius of the particles. Varying the shift δ from the centre, we analyse ground state structures for two, three and four hard spheres, using a simulated annealing procedure. We also compare earlier ground state results. We then consider a bulk system at finite temperatures and different densities. Using molecular dynamics simulations, we examine the equilibrium self-assembly properties for several shifts. Our results show that the shift of the dipole moment has a crucial impact on both the ground state configurations as well as the self-assembled structures at finite temperatures.

  10. Improvement of magnetosphere structure calculations using eccentric dipole to account for the internal magnetic field

    Science.gov (United States)

    Parunakian, David

    2014-05-01

    In this paper we build upon the results previously produced by numerous attempts, including our own, to approximate the geomagnetic field with a an eccentric dipole instead of spherical harmonics expansions. Among other motivations to do so is that dipole-related effects are much more pronounced relative to higher-order harmonics at large distances from the Earth, and that the shift of the order of magnitude about 0.1 Earth radii is significant enough for many magnetospheric structures such as the current sheet. We present the results of multivariate simulated annealing, which includes translational and rotational repositioning of the dipole. We also include similar results produced for Mercury and Saturn, and we extend Earth-related data with Oersted and Cluster measurements in order to further improve our accuracy.

  11. Ultra-long-range giant dipole molecules in crossed electric and magnetic fields

    CERN Document Server

    Kurz, Markus; Schmelcher, Peter

    2011-01-01

    We show the existence of ultra-long-range giant dipole molecules formed by a neutral alkali ground state atom that is bound to the decentered electronic wave function of a giant dipole atom. The adiabatic potential surfaces emerging from the interaction of the ground state atom with the giant dipole electron posses a rich topology depending on the degree of electronic excitation. Binding energies and the vibrational motion in the energetically lowest surfaces are analyzed by means of perturbation theory and exact diagonalization techniques. The resulting molecules are truly giant with internuclear distances up to several $\\mu m$. Finally, we demonstrate the existence of intersection manifolds of excited electronic states that potentially lead to a vibrational decay of the ground state atom dynamics.

  12. Methods for the Evaluation of Quench Temperature Profiles and their Application for LHC Superconducting Short Dipole Magnets

    CERN Document Server

    Sanfilippo, S

    2000-01-01

    This paper presents a study of the thermal effects on quench performance for several Large Hadron Collider single aperture short dipole models. The analysis is based on the temperature profile in a superconducting magnet evaluated after a quench. Peak temperatures and temperature gradients in the magnet coil are estimated for different thicknesses of insulation layer between the quench heaters and the coil and different powering and protection parameters. The results show clear correlation between the thermo-mechanical response of the magnet and quench performance. They also display that the optimisation of the position of quench heaters can reduce the decrease of training performance caused by the coexistence of a mechanical weak region and of a local temperature rise.

  13. Development of a Roebel-cable-based cosθ dipole: design and windability of magnet ends

    CERN Document Server

    Lorin, Clément; Fazilleau, Philippe; Kirby, Glyn; Rossi, Lucio; 10.1109/TASC.2016.2528542

    2016-01-01

    In the scope of the Future Circular Collider, work package 10, namely “Future Magnets”, of the EuCARD2 project aims at investigating accelerator quality magnets made of High Temperature Superconductors. The present paper deals with development of a cosθ dipole relying on Roebel cable technology. In the first part, we present in details the design of the dipole: the magnet generates 5 T in stand-alone mode with an overall current density of 684 A/mm². When operating in a background field of 13 T an extra field of 2 T can be provided by the cosθ insert due to mechanical limitations. A field increase up to 2.5 T is conceivable providing the addition of inner shell reinforcement that would reduce the magnet aperture from 40 mm to 30 mm. In the second part, winding tests of dummy Roebel cable are reported. They demonstrate the challenges stemming from the relative slippage of the cable tapes while winding that may be overcome by a lengthening of the longitudinal gap of the cable either by an increase of the...

  14. Direct measurement of the plasma loss width in an optimized, high ionization fraction, magnetic multi-dipole ring cusp

    Science.gov (United States)

    Cooper, C. M.; Weisberg, D. B.; Khalzov, I.; Milhone, J.; Flanagan, K.; Peterson, E.; Wahl, C.; Forest, C. B.

    2016-10-01

    The loss width of plasma in the WiPAL multi-dipole magnetic ring cusp [Cooper et al., Phys. Plasmas 21, 13505 (2014); Forest et al., J. Plasma Phys. 81, 345810501 (2015)] has been directly measured using a novel array of probes embedded in the insulating plasma limiters. The large plasma volume ( ˜10 m3), small loss area associated with strong rare earth permanent magnets ( Bo˜2.23 kG at face), and large heating power ( ≤200 kW) produces a broad range of electron temperatures ( 2 magnetic fields, differs from previous devices: the cusp loss width is much larger than the Debye length and electron gyroradius and comparable to the collision length. Plasma parameters measured at the surface of ceramic limiter tiles covering the magnets and along radial chords in the cusp magnetic field indicate that electron density and temperature are nearly constant on magnetic field lines and that the mirror forces play little role in confining the plasma other than to constrict the loss area. Particle balance modeling is used to determine the cross field diffusion coefficient base on the measured losses to the limiters. The experimentally determined cross field diffusion coefficient (which determines the cusp loss width) is consistent with ambipolar diffusion across five orders of magnitude. The ambipolar diffusion across a given field line is set primarily by the electron-neutral collisions in the region where the magnetic field is the weakest, even though these plasmas can have ionization fractions near 1.

  15. The reaction gammap-->pi0gamma'p and the magnetic dipole moment of the Delta+ 1232 resonance.

    Science.gov (United States)

    Kotulla, M; Ahrens, J; Annand, J R M; Beck, R; Caselotti, G; Fog, L S; Hornidge, D; Janssen, S; Krusche, B; McGeorge, J C; McGregor, I J D; Mengel, K; Messchendorp, J G; Metag, V; Novotny, R; Pfeiffer, M; Rost, M; Sack, S; Sanderson, R; Schadmand, S; Watts, D P

    2002-12-30

    The reaction gammap-->pi(0)gamma'p has been measured with the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI for energies between sqrt[s]=1221-1331 MeV. The cross section's differential in angle and energy have been determined for the photon gamma' in three bins of the excitation energy. This reaction channel provides access to the magnetic dipole moment of the Delta(+)(1232) resonance and, for the first time, a value of mu(Delta(+))=[2.7(+1.0)(-1.3)(stat)+/-1.5(syst)+/-3(theor)]mu(N) has been extracted.

  16. Design of MgB2 superconducting dipole magnet for particle beam transport in accelerators

    DEFF Research Database (Denmark)

    Abrahamsen, A.B.; Zangenberg, N.; Baurichter, A.

    2006-01-01

    A comprehensive analysis of the innovation potential of superconductivity at Risø was performed in February 2004 by the main author of this report [1]. Several suggestions for new products and new markets were formulated by the superconductivity group andexamined by the innovation staff at Risø. ...... accelerator, B = 4:4 Tesla and coil aperture D = 76 mm [6], which has been identified by Danfysik A/S as interesting. It isconcluded that MgB2 is useful for the dipole application and construction of a small test coil of one half of the magnet is planned in 2007....

  17. Algorithm for Automatic Detection, Localization and Characterization of Magnetic Dipole Targets Using the Laser Scalar Gradiometer

    Science.gov (United States)

    2016-06-01

    cell signals removes background field that consists of Earth’s field and any time- varying geodesic noise as well as common electronic noise...and the multiple dipoles may not be observable in some situations. An example would be the sensor passing in a straight line between two equal

  18. Research on the Rules of Electric Dipole in MagneticField%外磁场下电偶极子运动规律研究

    Institute of Scientific and Technical Information of China (English)

    任恒峰; 王清亮; 连润明; 孟峰

    2012-01-01

    This article negative ions. Using erg lts Yo dy di th scusses the interaction energy of the electric dipole that consisted of positive and e method of Taylor expansion, give the electric dipole's approximation potential en Based on the motion rules of free electric dipole, analyze the electric dipole's motion rules and solve namics equation by Newton's laws of motion in the external magnetic field . Finally, conclude the e lectric dipole's motion rules in the external magnetic field, that is to say, the electric dipole respectively does circular motion in radial of the eternal magnetic field, and does the simple harmonic oscillattion in tangential, whose overall trajectory is irregular spiral movement%利用泰勒展开取近似的方法,给出电偶极子的近似势能,并在自由电偶极子运动规律的基础上,讨论并得出了外磁场下电偶极子的运动规律:外磁场下电偶极子在径向做圆周运动,在切向做简谐振动,整体轨迹为不规则的螺旋式运动.

  19. Magnetic focusing of cold atomic beam with a 2D array of current-carrying wires

    Institute of Scientific and Technical Information of China (English)

    Yang Liu; Min Yun; Jianping Yin

    2006-01-01

    @@ A new scheme to realize a two-dimensional (2D) array of magnetic micro-lenses for a cold atomic beam,formed by an array of square current-carrying wires,is proposed.We calculate the spatial distributions of the magnetic fields from the array of current-carrying wires and the magnetic focusing potential for cold rubidium atoms,and study the dynamic focusing processes of cold atoms passing through the magnetic micro-lens array and its focusing properties by using Monte-Carlo simulations and trajectory tracing method.The result shows that the proposed micro-lens array can be used to focus effectively a cold atomic beam,even to load ultracold atoms or a BEC sample into a 2D optical lattice formed by blue detuned hollow beams.

  20. Effect of a magnetic field on massive-star winds - I. Mass-loss and velocity for a dipole field

    Science.gov (United States)

    Bard, Christopher; Townsend, Richard H. D.

    2016-11-01

    We generalize the Rigid-Field Hydrodynamic equations to accommodate arbitrary magnetic field topologies, resulting in a new Arbitrary Rigid-Field Hydrodynamic (ARFHD) formalism. We undertake a critical point calculation of the steady-state ARFHD equations with a CAK-type radiative acceleration and determine the effects of a dipole magnetic field on the usual CAK mass-loss rate and velocity structure. Enforcing the proper optically thin limit for the radiative line-acceleration is found to decrease both the mass-loss and wind acceleration, while rotation boosts both properties. We define optically thin correction and rotation parameters to quantify these effects on the global mass-loss rate and develop scaling laws for the surface mass-flux as a function of surface colatitude. These scaling laws are found to agree with previous laws derived from magnetohydrodynamic simulations of magnetospheres. The dipole magnetosphere velocity structure is found to differ from a global beta-velocity law, which contradicts a central assumption of the previously developed XADM model of X-ray emission from magnetospheres.

  1. Effect of a magnetic field on massive star winds I: mass-loss and velocity for a dipole field

    CERN Document Server

    Bard, Christopher

    2016-01-01

    We generalize the Rigid-Field Hydrodynamic equations to accommodate arbitrary magnetic field topologies, resulting in a new Arbitrary Rigid-Field hydrodynamic (ARFHD) formalism. We undertake a critical point calculation of the steady-state ARFHD equations with a CAK-type radiative acceleration and determine the effects of a dipole magnetic field on the usual CAK mass-loss rate and velocity structure. Enforcing the proper optically-thin limit for the radiative line-acceleration is found to decrease both the mass-loss and wind acceleration, while rotation boosts both properties. We define optically-thin-correction and rotation parameters to quantify these effects on the global mass-loss rate and develop scaling laws for the surface mass-flux as a function of surface colatitude. These scaling laws are found to agree with previous laws derived from magnetohydrodynamic simulations of magnetospheres. The dipole magnetosphere velocity structure is found to differ from a global beta-velocity law, which contradicts a ...

  2. Field induced by an axial magnetic dipole in the presence of two fused superconducting spheres: Analytic solution

    Science.gov (United States)

    Palaniappan, D.

    2009-04-01

    An exact solution for a magnetostatic boundary value problem involving two fused (overlapping) spheres placed in a field generated by an axial magnetic point dipole is constructed based on the image method. The basic idea is illustrated for two unequal superconducting spheres intersecting with a vertex angle π /2 and the analytical solution for the scalar magnetic potential satisfying the Neumann boundary condition at the surface is derived. The image solution for a dipole-twin-sphere configuration consists of three image dipoles—one inside each sphere and the third inside a pseudo-/virtual sphere—all located at the respective inverse points inside the superconducting two-sphere assembly. The levitation force acting on the two-sphere superconducting surface is also calculated for the overlapping geometry. These exact results can be used as a benchmark for testing numerical algorithms for overlapping spherical superconductors. Our simple approach also offers clues for solving the Neumann boundary value problem for vertex angles π /n, n is an integer, and other related superconducting geometries.

  3. Selective Excitation of Terahertz Magnetic and Electric Dipoles in Er3 + Ions by Femtosecond Laser Pulses in ErFeO3

    Science.gov (United States)

    Mikhaylovskiy, R. V.; Huisman, T. J.; Pisarev, R. V.; Rasing, Th.; Kimel, A. V.

    2017-01-01

    We show that femtosecond laser pulse excitation of the orthoferrite ErFeO3 triggers pico- and subpicosecond dynamics of magnetic and electric dipoles associated with the low energy electronic states of the Er3 + ions. These dynamics are readily revealed by using polarization sensitive terahertz emission spectroscopy. It is shown that by changing the polarization of the femtosecond laser pulse one can excite either electric dipole-active or magnetic dipole-active transitions between the Kramers doublets of the 15/2I4 ground state of the Er3 + (4 f11 ) ions. These observations serve as a proof of principle of polarization-selective control of both electric and magnetic degrees of freedom at terahertz frequencies, opening up new vistas for optical manipulation of magnetoelectric materials.

  4. Magnetisation and field quality of a cosine-theta dipole magnet wound with coated conductors for rotating gantry for hadron cancer therapy

    Science.gov (United States)

    Amemiya, Naoyuki; Sogabe, Yusuke; Sakashita, Masaki; Iwata, Yoshiyuki; Noda, Koji; Ogitsu, Toru; Ishii, Yusuke; Kurusu, Tsutomu

    2016-02-01

    Electromagnetic field analyses were carried out to study the influence of coated-conductor magnetisation, i.e. the screening (shielding) current, on the field quality of a dipole magnet in a rotating gantry for hadron cancer therapy. The analyses were made on the cross section of a cosine-theta dipole magnet in a rotating gantry for carbon ions, which generated 2.90 T of magnetic field. The temporal profile (temporal variation) of the magnet current was determined based on the actual excitation schemes of the magnets in the rotating gantry. The experimentally determined superconducting property of a coated conductor was considered, and we calculated the temporal evolutions of the current-density distributions in all the turns of coated conductors in the magnet. From the obtained current-density distributions, we calculated the multipole components of the magnetic field and evaluated the field quality of the magnet. The deviation in the dipole component from its designed value was up to approximately 25 mT, which was approximately 1% of the designed maximum dipole component. Its variation between repeated excitations was approximately 0.03%, and it drifted approximately 0.06% in 10 s. Some compensation schemes might be required to counteract such influence of magnetisation on the dipole component. Meanwhile, the higher multipole components were small, stable, and sufficiently reproducible for a magnet in rotating gantries, i.e. |b 3| ˜ 1.1 × 10-3 and |Δb 3| ˜ 0.2 × 10-3 in 10 s.

  5. Review of selected coil and collared-coil assembly data from 10-M-long, 50-MM-Twin-aperture LHC dipole magnet prototypes

    Energy Technology Data Exchange (ETDEWEB)

    Devred, A

    1999-02-01

    In 1991, the Laboratoire Europeen pour la Physique des Particules (CERN) has launched the fabrication in industry of seven 10 m long, 50 mm twin aperture dipole magnet prototypes for the Large Hadron Collider (LHC). The design and specific features of these magnets have been described elsewhere. In this paper, we review some of the coil and collared-coil assembly data and we analyze the influence of tooling imperfections on magnet assembly. (author)

  6. Dissipation of Alfven wave pulses propagating along dipole magnetic tubes with reflections at the ionosphere

    NARCIS (Netherlands)

    Erkaev, NV; Shaidurov, VA; Semenov, VS; Biernat, HK; Heidorn, D; Lakhina, GS

    2006-01-01

    A ratio of the maximal and minimal cross sections of the magnetic tube (contraction ratio) is a crucial parameter which affects very strongly on reflections of MHD wave pulses propagating along a narrowing magnetic flux tube. In cases of large contraction ratios of magnetospheric magnetic tubes, the

  7. Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets

    CERN Document Server

    Erni, W; Krusche, B; Steinacher, M; Heng, Y; Liu, Z; Liu, H; Shen, X; Wang, O; Xu, H; Becker, J; Feldbauer, F; Heinsius, F -H; Held, T; Koch, H; Kopf, B; Pelizaeus, M; Schröder, T; Steinke, M; Wiedner, U; Zhong, J; Bianconi, A; Bragadireanu, M; Pantea, D; Tudorache, A; Tudorache, V; De Napoli, M; Giacoppo, F; Raciti, G; Rapisarda, E; Sfienti, C; Bialkowski, E; Budzanowski, A; Czech, B; Kistryn, M; Kliczewski, S; Kozela, A; Kulessa, P; Pysz, K; Schäfer, W; Siudak, R; Szczurek, A; zycki, W Czy; Domagala, M; Hawryluk, M; Lisowski, E; Lisowski, F; Wojnar, L; Gil, D; Hawranek, P; Kamys, B; Kistryn, St; Korcyl, K; Krzemien, W; Magiera, A; Moskal, P; Rudy, Z; Salabura, P; Smyrski, J; Wronska, A; Al-Turany, M; Augustin, I; Deppe, H; Flemming, H; Gerl, J; Goetzen, K; Hohler, R; Lehmann, D; Lewandowski, B; Lühning, J; Maas, F; Mishra, D; Orth, H; Peters, K; Saitô, T; Schepers, G; Schmidt, C J; Schmitt, L; Schwarz, C; Voss, B; Wieczorek, P; Wilms, A; Brinkmann, K -T; Freiesleben, H; Jaekel, R; Kliemt, R; Wuerschig, T; Zaunick, H -G; Abazov, V M; Alexeev, G; Arefev, A; Astakhov, V I; Barabanov, M Yu; Batyunya, B V; Davydov, Yu I; Dodokhov, V Kh; Efremov, A A; Fedunov, A G; Feshchenko, A A; Galoyan, A S; Grigorian, S; Karmokov, A; Koshurnikov, E K; Kudaev, V Ch; Lobanov, V I; Lobanov, Yu Yu; Makarov, A F; Malinina, L V; Malyshev, V L; Mustafaev, G A; Olshevski, A; Pasyuk, M A; Perevalova, E A; Piskun, A A; Pocheptsov, T A; Pontecorvo, G; Rodionov, V K; Rogov, Yu N; Salmin, R A; Samartsev, A G; Sapozhnikov, M G; Shabratova, A; Shabratova, G S; Skachkova, A N; Skachkov, N B; Strokovsky, E A; Suleimanov, M K; Teshev, R Sh; Tokmenin, V V; Uzhinsky, V V; Vodopyanov, A S; Zaporozhets, S A; Zhuravlev, N I; Zorin, A G; Branford, D; Föhl, K; Glazier, D; Watts, D; Woods, P; Eyrich, W; Lehmann, A; Teufel, A; Dobbs, S; Metreveli, Z; Seth, K; Tann, B; Tomaradze, A G; Bettoni, D; Carassiti, V; Cecchi, A; Dalpiaz, P; Fioravanti, E; Garzia, I; Negrini, M; Savri`e, M; Stancari, G; Dulach, B; Gianotti, P; Guaraldo, C; Lucherini, V; Pace, E; Bersani, A; Macri, M; Marinelli, M; Parodi, R F; Brodski, I; Döring, W; Drexler, P; Düren, M; Gagyi-Palffy, Z; Hayrapetyan, A; Kotulla, M; Kühn, W; Lange, S; Liu, M; Metag, V; Nanova, M; Novotny, R; Salz, C; Schneider, J; Schoenmeier, P; Schubert, R; Spataro, S; Stenzel, H; Strackbein, C; Thiel, M; Thoering, U; Yang, S; Clarkson, T; Cowie, E; Downie, E; Hill, G; Hoek, M; Ireland, D; Kaiser, R; Keri, T; Lehmann, I; Livingston, K; Lumsden, S; MacGregor, D; McKinnon, B; Murray, M; Protopopescu, D; Rosner, G; Seitz, B; Yang, G; Babai, M; Biegun, A K; Bubak, A; Guliyev, E; Jothi, V S; Kavatsyuk, M; Löhner, H; Messchendorp, J; Smit, H; van der Weele, J C; García, F; Riska, D -O; Büscher, M; Dosdall, R; Dzhygadlo, R; Gillitzer, A; Grunwald, D; Jha, V; Kemmerling, G; Kleines, H; Lehrach, A; Maier, R; Mertens, M; Ohm, H; Prasuhn, D; Randriamalala, T; Ritman, J; Roeder, M; Stockmanns, T; Wintz, P; Wüstner, P; Kisiel, J; Li, S; Li, Z; Sun, Z; Xu, H; Fissum, S; Hansen, K; Isaksson, L; Lundin, M; Schröder, B; Achenbach, P; Espi, M C Mora; Pochodzalla, J; Sanchez, S; Sanchez-Lorente, A; Dormenev, V I; Fedorov, A A; Korzhik, M V; Missevitch, O V; Balanutsa, V; Chernetsky, V; Demekhin, A; Dolgolenko, A; Fedorets, P; Gerasimov, A; Goryachev, V; Boukharov, A; Malyshev, O; Marishev, I; Semenov, A; Hoeppner, C; Ketzer, B; Konorov, I; Mann, A; Neubert, S; Paul, S; Weitzel, Q; Khoukaz, A; Rausmann, T; Täschner, A; Wessels, J; Varma, R; Baldin, E; Kotov, K; Peleganchuk, S; Tikhonov, Yu; Boucher, J; Hennino, T; Kunne, R; Ong, S; Pouthas, J; Ramstein, B; Rosier, P; Sudol, M; Van de Wiele, J; Zerguerras, T; Dmowski, K; Korzeniewski, R; Przemyslaw, D; Slowinski, B; Boca, G; Braghieri, A; Costanza, S; Fontana, A; Genova, P; Lavezzi, L; Montagna, P; Rotondi, A; Belikov, N I; Davidenko, A M; Derevshchikov, A A; Goncharenko, Yu M; Grishin, V N; Kachanov, V A; Konstantinov, D A; Kormilitsin, V A; Kravtsov, V I; Matulenko, Yu A; Melnik, Y M; Meshchanin, A P; Minaev, N G; Mochalov, V V; Morozov, D A; Nogach, L V; Nurushev, S B; Ryazantsev, A V; Semenov, P A; Soloviev, L F; Uzunian, A V; Vasilev, A N; Yakutin, A E; Baeck, T; Cederwall, B; Bargholtz, C; Geren, L; Tegnér, P E; Belostotskii, S; Gavrilov, G; Itzotov, A; Kiselev, A; Kravchenko, P; Manaenkov, S; Miklukho, O; Naryshkin, Yu; Veretennikov, D; Vikhrov, V; Zhadanov, A; Fava, L; Panzieri, D; Alberto, D; Amoroso, A; Botta, E; Bressani, T; Bufalino, S; Bussa, M P; Busso, L; De Mori, F; Destefanis, M; Ferrero, L; Grasso, A; Greco, M; Kugathasan, T; Maggiora, M; Marcello, S; Serbanut, G; Sosio, S; Bertini, R; Calvo, D; Coli, S; De Remigis, P; Feliciello, A; Filippi, A; Giraudo, G; Mazza, G; Rivetti, A; Szymanska, K; Tosello, F; Wheadon, R; Morra, O; Agnello, M; Iazzi, F; Szymanska, K; Birsa, R; Bradamante, F; Bressan, A; Martin, A; Clement, H; Ekström, C; Calén, H; Grape, S; Hoeistad, B; Johansson, T; Kupsc, A; Marciniewski, P; Thomé, E; Zlomanczuk, Yu; Díaz, J; Ortiz, A; Borsuk, S; Chlopik, A; Guzik, Z; Kopec, J; Kozlovskii, T; Melnychuk, D; Plominski, M; Szewinski, J; Traczyk, K; Zwieglinski, B; Bühler, P; Gruber, A; Kienle, P; Marton, J; Widmann, E; Zmeskal, J

    2009-01-01

    This document is the Technical Design Report covering the two large spectrometer magnets of the PANDA detector set-up. It shows the conceptual design of the magnets and their anticipated performance. It precedes the tender and procurement of the magnets and, hence, is subject to possible modifications arising during this process.

  8. Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets

    NARCIS (Netherlands)

    Erni, W.; Keshelashvili, I; Krusche, B.

    2009-01-01

    This document is the Technical Design Report covering the two large spectrometer magnets of the PANDA detector set-up. It shows the conceptual design of the magnets and their anticipated performance. It precedes the tender and procurement of the magnets and, hence, is subject to possible

  9. Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets

    NARCIS (Netherlands)

    Erni, W.; Keshelashvili, I; Krusche, B.

    2009-01-01

    This document is the Technical Design Report covering the two large spectrometer magnets of the PANDA detector set-up. It shows the conceptual design of the magnets and their anticipated performance. It precedes the tender and procurement of the magnets and, hence, is subject to possible modificatio

  10. Tevatron AC dipole system

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, R.; Kopp, S.E.; /Texas U.; Jansson, A.; Syphers, M.J.; /Fermilab

    2007-06-01

    The AC dipole is an oscillating dipole magnet which can induce large amplitude oscillations without the emittance growth and decoherence. These properties make it a good tool to measure optics of a hadron synchrotron. The vertical AC dipole for the Tevatron is powered by an inexpensive high power audio amplifier since its operating frequency is approximately 20 kHz. The magnet is incorporated into a parallel resonant system to maximize the current. The use of a vertical pinger magnet which has been installed in the Tevatron made the cost relatively inexpensive. Recently, the initial system was upgraded with a more powerful amplifier and oscillation amplitudes up to 2-3{sigma} were achieved with the 980 GeV proton beam. This paper discusses details of the Tevatron AC dipole system and also shows its test results.

  11. EUV magnetic-dipole lines from highly-charged high-Z ions with an open 3d shell

    CERN Document Server

    Osin, D; Reader, J; Ralchenko, Yu

    2012-01-01

    The electron beam ion trap (EBIT) at the National Institute of Standards and Technology was used to produce highly-charged ions of hafnium, tantalum and gold with an open 3d shell. The extreme-ultraviolet (EUV) spectra from these ions were recorded with a flat-field grazing-incidence spectrometer in the wavelength range of 4.5 nm to 25 nm. A total of 133 new spectral lines, primarily due to magnetic-dipole transitions within the ground-state $3d^n$ configurations of the Co-like to K-like ions, were identified by comparing energy-dependent experimental spectra with a detailed collisional-radiative modeling of the EBIT plasma.

  12. Heat transfer analysis of Jeffery fluid flow over a stretching sheet with suction/injection and magnetic dipole effect

    Directory of Open Access Journals (Sweden)

    A. Zeeshan

    2016-09-01

    Full Text Available The purpose of the present paper was to investigate the flow and heat transfer of Jeffery fluid past a linearly stretching sheet with the effect of a magnetic dipole. The governing differential equations of motion and heat transfer are transformed into nonlinear coupled ordinary differential equations (ODEs using appropriate similarity transformations. Then the ODEs are solved by adopting two different schemes, Runge–Kutta with shooting technique and series solution based on GA and NM. The effect of various physical parameters including ferromagnetic interaction parameter (β, Deborah number (γ1, Prandtl number (Pr, suction/injection parameter (S, ratio of relaxation to retardation times (λ2 on velocity and temperature profiles is illustrated graphically and in tabular form by considering two types of thermal process namely prescribed surface temperature (PST and prescribed heat flux (PHF. Comparison with available results for particular cases is found an excellent agreement.

  13. Engineering, Manufacture and Preliminary Testing of the ITER Toroidal Field (TF) Magnet Helium Cold Circulator

    Science.gov (United States)

    Rista, P. E. C.; Shull, J.; Sargent, S.

    2015-12-01

    The ITER cryodistribution system provides the supercritical Helium (SHe) forced flow cooling to the magnet system using cold circulators. The cold circulators are located in each of five separate auxiliary cold boxes planned for use in the facility. Barber-Nichols Inc. has been awarded a contract from ITER-India for engineering, manufacture and testing of the Toroidal Field (TF) Magnet Helium Cold Circulator. The cold circulator will be extensively tested at Barber-Nichols’ facility prior to delivery for qualification testing at the Japan Atomic Energy Agency's (JAEA) test facility at Naka, Japan. The TF Cold Circulator integrates features and technical requirements which Barber-Nichols has utilized when supplying helium cold circulators worldwide over a period of 35 years. Features include a vacuum-jacketed hermetically sealed design with a very low helium leak rate, a heat shield for use with both nitrogen & helium cold sources, a broad operating range with a guaranteed isentropic efficiency over 70%, and impeller design features for high efficiency. The cold circulator will be designed to meet MTBM of 17,500 hours and MTBF of 36,000 hours. Vibration and speed monitoring are integrated into a compact package on the rotating assembly with operation and health monitoring in a multi-drop PROFIBUS communication environment using an electrical cabinet with critical features and full local and network PLC interface and control. For the testing in Japan and eventual installation in Europe, the cold circulator must be certified to the Japanese High Pressure Gas Safety Act (JHPGSA) and CE marked in compliance with the European Pressure Equipment Directive (PED) including Essential Safety Requirements (ESR). The test methodology utilized at Barber-Nichols’ facility and the resulting test data, validating the high efficiency of the TF Cold Circulator across a broad operating range, are important features of this paper.

  14. Compensation of the Persistent Current Multipoles in the LHC Dipoles by making the Coil Protection Sheet from Soft Magnetic Material

    CERN Document Server

    Völlinger, C

    2000-01-01

    This note presents a scheme for compensating the persistent current multipole errors of the LHC dipoles by making the coil protection sheets from soft magnetic material of 0.5 mm thickness. The material properties assumed in this study are those of iron sheets with a very low content of impurities (99.99% pure Fe). The non-linearities in the upramp cycle on the b3 multipole component can be reduced by the factor of four (while decreasing the b5 variation by the factor of two. Using sheets of slightly different thicknesses offers a tuning possibility for the series magnet coils and can compensate deviations arising from cables of different suppliers. The calculation method is based on a semi-analytical hysteresis model for hard superconductors and an M(B) - iteration using the method of coupled boundary elements - finite elements (BEM - FEM). It is now possible to compute persistent current multipole errors of geometries with arbitrarily shaped iron yokes and thin layers of soft magnetic material such as tunin...

  15. Status of the LHC Short Dipole Model Programme

    CERN Document Server

    Tommasini, D; Sanfilippo, S; Siemko, A; Vanenkov, I; Wyss, C

    2000-01-01

    The 1-m model program for the main LHC dipoles is now mainly focussed on double-aperture magnets. In the past years an intensive program based on single-aperture dipoles allowed to select the series-design features among several variants for the coil cross section, the material of the collars and of the coil end spacers, the coil pre-stress and the cable insulation. The recent double-aperture models are dedicated to the fine-tuning of the baseline design and the manufacture of the coil ends. This paper reports about the fabrication and testing of these magnets and the results relevant for the series production of the 15-m long full-size dipole cold masses.

  16. A Line Integral Representation of the Physical Optics Far Field from Plane PEC Scatterers Illuminated by Electric or Magnetic Hertzian Dipoles

    DEFF Research Database (Denmark)

    Arslanagic, S.; Meincke, Peter; Jørgensen, E.;

    2002-01-01

    We derive a line integral representation of the physical optics (PO) scattered far field that yields the exact same result as the conventional surface radiation integral. This representation applies to a perfectly electrically conducting plane scatterer illuminated by electric or magnetic Hertzian...... dipoles....

  17. A model for correlating 4. 2-K performance with room-temperature mechanical characteristics in superconducting test dipole magnets for the Superconducting Super Collider (SSC)

    Energy Technology Data Exchange (ETDEWEB)

    Ige, O.O.; Lyon, R.H.; Iwasa, Y. (Francis Bitter National Magnet Laboratory Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States))

    1992-03-15

    The longitudinal attenuation of impact-generated pulses in ten superconducting dipole magnets was measured at room temperature. A lumped-parameter model was constructed for the collared dipole. Using the method of nonlinear least-squares, the model was used to estimate the internal damping in the main components of the dipoles and the coupling resistances between the components: collars, inner, and outer coils. A positive correlation was found between the collar-inner coil coupling resistance and the 4.2-K performance of the magnets: the higher the coupling resistance, the fewer the number of quenches required to reach design operating current. There was virtually no correlation between any of the other internal or coupling resistances and 4.2-K performance. These observations are explained in terms of frictional slip of the inner coil against the collars causing premature quenches. The magnets are more susceptible to quenches at the collar-inner coil interface than at the collar-outer coil interface because the inner coil is subject to higher fields and forces. The experiment is potentially useful as a technique for screening high-performance superconducting magnets such as Superconducting Super Collider (SSC) dipoles at room temperature.

  18. Electron beam focusing in a racetrack microtron by means of rotated two-sector dipole magnets

    Science.gov (United States)

    Delhez, J. L.; Webers, G. A.; Botman, J. I. M.; Hagedoorn, H. L.; Muzio, D.; Timmermans, C. J.

    1992-05-01

    We present an unconventional method of electron beam focusing in a racetrack microtron (RTM). The RTM bending magnets have a two-sector shape (valley and hill) and are slightly rotated in their median plane in order to guarantee closed orbits. Then, isochronism is automatically fulfilled. Comparison between this new arrangement and a previous three-sector design, inspired by Froelich [1], shows that the focusing properties are greatly improved, e.g. regarding beam acceptance and construction sensitivity. We will give a detailed description of the two-sector layout, make a comparison with the three-sector magnet (acceptance and sensitivity) and give magnet parameters for optimum performance.

  19. Magnetic flux transport and the sun's dipole moment - New twists to the Babcock-Leighton model

    Science.gov (United States)

    Wang, Y.-M.; Sheeley, N. R., Jr.

    1991-01-01

    The mechanisms that give rise to the sun's large-scale poloidal magnetic field are explored in the framework of the Babcock-Leighton (BL) model. It is shown that there are in general two quite distinct contributions to the generation of the 'alpha effect': the first is associated with the axial tilts of the bipolar magnetic regions as they erupt at the surface, while the second arises through the interaction between diffusion and flow as the magnetic flux is dispersed over the surface. The general relationship between flux transport and the BL dynamo is discussed.

  20. Derivation of the magnetic field on a metal cylinder excited by a longitudinal magnetic dipole transmitter: II. Cylinder in a two-layer dissipative dielectric medium

    Science.gov (United States)

    Freedman, Robert

    2016-11-01

    We derive an exact convergent analytical solution for the complex frequency-dependent magnetic field on the surface of an infinitely long and perfectly conducting metal cylinder situated in a cylindrically layered dissipative medium. The inhomogeneous medium consists of two exterior cylindrical layers that are concentric with the cylinder. The magnetic field on the cylinder is excited by a longitudinally oriented oscillating magnetic dipole transmitter on the cylinder surface. An exact analytical solution to this problem has not been previously published and is of theoretical as well as practical importance, e.g., in modeling the responses of electromagnetic wave propagation well logging tools. It is shown that the magnetic field on the cylinder surface can be expressed as a real-axis integral; however, the integrand oscillates rapidly and diverges for large values of the integration variable. The real-axis integral is replaced by the sum of two convergent branch line integrals and a sum over the residues of the complex poles in the integrand of the real-axis integral. The poles correspond physically to waveguide modes that propagate with discrete wave numbers. A pole search algorithm is developed to locate the positions of the poles and compute their residues. Phase shifts and attenuations of the magnetic field between receivers for a 1.1 GHz well logging tool are computed to elucidate the pole spectra and the relative contributions of the waveguide modes and the branch cut integrals for different thicknesses of the innermost dielectric layer and for different layer properties.

  1. A first dipole magnet was delivered to its final location in the LHC tunnel (2)

    CERN Multimedia

    2005-01-01

    The first superconducting magnet was transported to its final location between Points 8 and 1 by a specially designed vehicle. It was then positioned with great precision and unloaded using a transfer table.

  2. First on-line $\\beta$-NMR on oriented nuclei magnetic dipole moments of the $\

    CERN Document Server

    Giles, T; Stone, N J; Van Esbroeck, K; White, G; Wöhr, A; Veskovic, M; Towner, I S; Mantica, P F; Prisciandaro, J I; Morrissey, D J; Fedosseev, V; Mishin, V I; Köster, U; Walters, W B

    2000-01-01

    The first fully on-line use of the angular distribution of $\\beta$ - emission in detection of NMR of nuclei oriented at low temperatures is reported. The magnetic moments of the single valence particle, intermediate mass, isotopes $^{67}$Ni($\

  3. Magnetic dipole moment of the doubly closed-shell plus one proton nucleus $^{49}$Sc

    CERN Multimedia

    Gaulard, C V; Walters, W; Nishimura, K; Muto, S; Bingham, C R

    It is proposed to measure the magnetic moment of $^{49}$Sc by the Nuclear Magnetic Resonance on Oriented Nuclei (NMR-ON) method using the NICOLE on-line nuclear orientation facility. $^{49}$Sc is the neutron rich, doubly closed-shell, nucleus $^{48}$Ca plus one proton. Results will be used to deduce the effective g-factors in the $^{48}$Ca region with reference to nuclear structure and meson exchange current effects.

  4. A novel controllable double-layer magnetic lattice with cold atoms

    Institute of Scientific and Technical Information of China (English)

    Min Yun; Jianping Yin

    2005-01-01

    We propose a novel array of controllable double-well magnetic microtraps for cold atoms by using an array of square current-carrying wires and two additional bias magnetic fields. Arrays of double layer magnetooptical traps (MOTs) and Ioffe traps can be constructed by using same wire configurations and different currents and bias fields. Furthermore, the array of double-well magnetic microtraps can be continuously evolved as an array of single-well magnetic microtraps by reducing the currents in the wires. Our study shows that our scheme can be used to realize a controllable double-layer magnetic lattice with cold atoms, to form array of Bose-Einstein condensations (BECs), or to study atom interference, and so on.

  5. Comparison of Electric Dipole and Magnetic Dipole Models for Electromagnetic Pulse Generated by Nuclear Detonation in Space%两种深空核爆炸辐射电磁脉冲模型的比较

    Institute of Scientific and Technical Information of China (English)

    朱梦; 周辉; 程引会; 李宝忠; 吴伟; 李进玺; 马良; 赵墨

    2013-01-01

    深空核爆炸通过电偶极子和磁偶极子两种辐射机制产生电磁脉冲.本文具体分析了两种辐射模型产生电磁脉冲的物理机制,并估算了远处观察点的辐射电场.计算表明,电子以高斯波形出射时,百吨TNT当量爆炸在km量级范围内产生的电偶极子和磁偶极子辐射电场强度分别为kV/m和10 V/m量级.深空中地磁感应强度较弱,电子的角向运动相比初始方向运动是小量,因而磁偶极子的辐射强度远小于电偶极子的.%Electromagnetic pulse can be generated by the nuclear detonation in space via two radiation mechanisms.The electric dipole and magnetic dipole models were analyzed.The electric radiation in the far field generated by two models was calculated as well.Investigations show that in the case of one hundred TNT yield detonations,when electrons are emitted according to the Gaussian shape,two radiation models can give rise to the electric field in great distances with amplitudes of kV/m and tens of V/m,independently.Because the geomagnetic field in space is not strong and the electrons' angular motion is much weaker than the motion in the original direction,radiations from the magnetic dipole model are much weaker than those from the electric dipole model.

  6. Magnetohydrodynamic Simulations of Disk GalaxyFormation: the Magnetization of The Cold and Warm Medium

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peng; Abel, Tom; /KIPAC, Menlo Park /Santa Barbara, KITP

    2007-12-18

    Using magnetohydrodynamic (MHD) adaptive mesh refinement simulations, we study the formation and early evolution of disk galaxies with a magnetized interstellar medium. For a 10{sup 10} M{sub {circle_dot}} halo with initial NFW dark matter and gas profiles, we impose a uniform 10{sup -9} G magnetic field and follow its collapse, disk formation and evolution up to 1 Gyr. Comparing to a purely hydrodynamic simulation with the same initial condition, we find that a protogalactic field of this strength does not significantly influence the global disk properties. At the same time, the initial magnetic fields are quickly amplified by the differentially rotating turbulent disk. After the initial rapid amplification lasting {approx} 500 Myr, subsequent field amplification appears self-regulated. As a result, highly magnetized material begin to form above and below the disk. Interestingly, the field strengths in the self-regulated regime agrees well with the observed fields in the Milky Way galaxy both in the warm and the cold HI phase and do not change appreciably with time. Most of the cold phase shows a dispersion of order ten in the magnetic field strength. The global azimuthal magnetic fields reverse at different radii and the amplitude declines as a function of radius of the disk. By comparing the estimated star formation rate (SFR) in hydrodynamic and MHD simulations, we find that after the magnetic field strength saturates, magnetic forces provide further support in the cold gas and lead to a decline of the SFR.

  7. Magnetohydrodynamic Simulations of Disk GalaxyFormation: the Magnetization of The Cold and Warm Medium

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peng; Abel, Tom; /KIPAC, Menlo Park /Santa Barbara, KITP

    2007-12-18

    Using magnetohydrodynamic (MHD) adaptive mesh refinement simulations, we study the formation and early evolution of disk galaxies with a magnetized interstellar medium. For a 10{sup 10} M{sub {circle_dot}} halo with initial NFW dark matter and gas profiles, we impose a uniform 10{sup -9} G magnetic field and follow its collapse, disk formation and evolution up to 1 Gyr. Comparing to a purely hydrodynamic simulation with the same initial condition, we find that a protogalactic field of this strength does not significantly influence the global disk properties. At the same time, the initial magnetic fields are quickly amplified by the differentially rotating turbulent disk. After the initial rapid amplification lasting {approx} 500 Myr, subsequent field amplification appears self-regulated. As a result, highly magnetized material begin to form above and below the disk. Interestingly, the field strengths in the self-regulated regime agrees well with the observed fields in the Milky Way galaxy both in the warm and the cold HI phase and do not change appreciably with time. Most of the cold phase shows a dispersion of order ten in the magnetic field strength. The global azimuthal magnetic fields reverse at different radii and the amplitude declines as a function of radius of the disk. By comparing the estimated star formation rate (SFR) in hydrodynamic and MHD simulations, we find that after the magnetic field strength saturates, magnetic forces provide further support in the cold gas and lead to a decline of the SFR.

  8. Accelerator Quality HTS Dipole Magnet Demonstrator Designs for the EuCARD-2, 5 Tesla 40 mm Clear Aperture Magnet

    CERN Document Server

    Kirby, G A; Ballarino, A; Bottura, L; Chouika, N; Clement, S; Datskov, V; Fajardo, L; Fleiter, J; Gauthier, R; Gentini, L; Lambert, L; Lopes, M; Perez, J C; de Rijk, G; Rijllart, A; Rossi, L; ten Kate, H; Durante, M; Fazilleau, P; Lorin, C; Härö, E; Stenvall, A; Caspi, S; Marchevsky, M; Goldacker, W; Kario, A

    2015-01-01

    Future high-energy accelerators will need very high magnetic fields in the range of 20 T. The EuCARD-2 work-package-10 is a collaborative push to take HTS materials into an accelerator quality demonstrator magnet. The demonstrator will produce 5 T standalone and between 17 T and 20 T, when inserted into the 100 mm aperture of Fresca-2 high field out-sert magnet. The HTS magnet will demonstrate the field strength and field quality that can be achieved. An effective quench detection and protection system will have to be developed to operate with the HTS superconducting materials. This paper presents a ReBCO magnet design using multi strand Roebel cable that develops a stand-alone field of 5 T in a 40 mm clear aperture and discusses the challenges associated with good field quality using this type of material. A selection of magnet designs is presented as result of a first phase of development.

  9. Accelerator Quality HTS Dipole Magnet Demonstrator designs for the EuCARD-2, 5 Tesla 40 mm Clear Aperture Magnet

    CERN Document Server

    Kirby, G; Ballarino, A; Bottura, L; Chouika, N; Clement, S; Datskov, V; Fajardo, L; Fleiter, J; Gauthier, R; Lambert, L; Lopes, M; Perez, J; DeRijk, G; Rijllart, A; Rossi, L; Ten Kate, H; Durante, M; Fazilleau, P; Lorin, C; Haro, E; Stenvall, A; Caspi, S; Marchevsky, M; Goldacker, W; Kario, A

    2014-01-01

    Future high-energy accelerators will need very high magnetic fields in the range of 20 T. The EuCARD-2 work-package-10 is a collaborative push to take HTS materials into an accelerator quality demonstrator magnet. The demonstrator will produce 5 T standalone and between 17 T and 20 T, when inserted into the 100 mm aperture of Fresca-2 high field out-sert magnet. The HTS magnet will demonstrate the field strength and field quality that can be achieved. An effective quench detection and protection system will have to be developed to operate with the HTS superconducting materials. This paper presents a ReBCO magnet design using multi strand Roebel cable that develops a stand-alone field of 5 T in a 40 mm clear aperture and discusses the challenges associated with good field quality using this type of material. A selection of magnet designs is presented as result of a first phase of development.

  10. Complete Electric and Magnetic Dipole Response of 208Pb from Zero-Degree Inelastic Proton Scattering

    Science.gov (United States)

    von Neumann-Cosel, P.

    2015-11-01

    Small-angle polarized proton scattering including 0° off 208Pb has been studied at the RCNP cyclotron with high energy resolution of the order of 25 keV (FWHM). The complete E1 strength distribution from 5 to 20 MeV could be extracted from the data and is found to agree well with available data. New E1 strength is found in the energy region above threshold inacessible in previous experiments. The total E1 polarizability as well as the properties of the pygmy dipole resonance could be determined with high precision providing important experimental constraints on the neutron skin thickness in 208Pb and the symmetry energy of neutron-rich matter. Additionally, information on the spin-M1 strength in 208Pb was obtained. Assuming dominance of the central spin-isospinflip part of the effective proton-nucleus interaction, the B(M1) transition strength can be derived. It corresponds well with data from electromagnetic probes indicating that the reaction can provide information on the poorly known spin-M1 resonance in heavy nuclei.

  11. Stability of the Horizontal Curvature of the LHC Cryodipoles During Cold Tests

    CERN Document Server

    Cano, E D Fernandez; García-Pérez, J; Jeanneret, Jean Bernard; Poncet, A; Seyvet, F; Tovar-Gonzalez, A; Wildner, E; IEEE Trans. Nucl. Sci.

    2006-01-01

    The LHC will be composed of 1232 horizontally curved, 15 meter long, superconducting dipole magnets cooled at 1.9 K. They are supported within their vacuum vessel by three Glass Fiber Reinforced Epoxy (GFRE) support posts. Each cryodipole is individually cold tested at CERN before its installation and interconnection in the LHC 27 km circumference tunnel. As the magnet geometry under cryogenic operation is extremely important for the LHC machine aperture, a new method has been developed at CERN in order to monitor the magnet curvature change between warm and cold states. It enabled us to conclude that there is no permanent horizontal curvature change of the LHC dipole magnet between warm and cold states, although a systematic horizontal transient deformation during cool-down was detected. This deformation generates loads in the dipole supporting system; further investigation permitted us to infer this behavior to the asymmetric thermal contraction of the rigid magnet thermal shield during cool-down. Controlli...

  12. Magnetic dipole moments of High-K isomeric states in Hf isotopes

    CERN Multimedia

    Walters, W; Nishimura, K; Bingham, C R

    2007-01-01

    It is proposed to make precision measurements of the magnetic moments of 5 multi-quasi-particle K-isomers in Hf nuclei by the Nuclear Magnetic Resonance of Oriented Nuclei (NMR/ON) technique using the NICOLE on-line nuclear orientation facility and exploiting the unique HfF$_{3}$ beams recently available at ISOLDE. Results will be used to extract single-particle and collective g-factors of the isomeric states and their excitations and to shed new light on their structure.

  13. Analogue of the quantum Hall effect for neutral particles with magnetic dipole moment

    Science.gov (United States)

    Ribeiro, L. R.; Passos, E.; Furtado, C.; Sergeenkov, S.

    2017-03-01

    In this paper we investigate a possibility for the existence of an analog of the Quantum Hall Effect for neutral particles with a permanent magnetic moment μ in the presence of crossed inhomogeneous magnetic and electric fields. We predict the appearance of Hall conductivity σH = (e2 / h) ν (μ) with the Landau filling factor ν (μ) ∝μ2. The estimates of the model parameters suggest quite an optimistic possibility to experimentally verify this prediction in optically trapped clouds of atomic BEC.

  14. Field Quality of the Short Superconducting Dipole Models for the LHC

    CERN Document Server

    Ang, Z; Sanfilippo, S; Siemko, A; Tommasini, D; Venturini-Delsolaro, W; Walckiers, L

    2002-01-01

    A full characterization of the magnetic field in warm and cold conditions was performed as a part of the standard test on the LHC 1-m long superconducting dipole models. Furthermore, dedicated measurement campaigns addressed the effect of current cycles and quenches on field quality. Powering and quenches were found to generate characteristic instabilities in the geometric harmonics. Detailed results are presented on this phenomenon, as well as correlations between warm and cold measurements and field reconstructions.

  15. Field quality of the short superconducting dipole models for the LHC

    CERN Document Server

    Venturini-Delsolaro, W; Bottura, L; Sanfilippo, S; Siemko, A; Tommasini, D; Walckiers, L

    2002-01-01

    A full characterization of the magnetic field in warm and cold conditions was performed as a part of the standard test on the LHC 1- m long superconducting dipole models. Furthermore, dedicated measurement campaigns addressed the effect of current cycles and quenches on field quality. Powering and quenches were found to generate characteristic instabilities in the geometric harmonics. Detailed results are presented on this phenomenon, as well as correlations between warm and cold measurements and field reconstructions. (9 refs).

  16. The optimised sc dipole of SIS100 for series production

    Science.gov (United States)

    Roux, Christian; Mierau, Anna; Bleile, Alexander; Fischer, Egbert; Kaether, Florian; Körber, Boris; Schnizer, Pierre; Sugita, Kei; Szwangruber, Piotr

    2017-02-01

    At the international facility for antiproton and ion research (FAIR) in Darmstadt, Germany, an accelerator complex is developed for fundamental research in various fields of modern physics. In the SIS100 heavy-ion synchrotron, the main accelerator of FAIR, superconducting dipoles are used to bend the particle beam. The fast ramped dipoles are 3 m long super-ferric curved magnets operated at 4.5 K. The demands on field homogeneity required for sufficient beam stability are given by ΔB/B ≤ ±6 · 10‑4. An intense measurement program of the First of Series (FoS) dipole showed excellent quench behavior and lower than expected AC losses yielding the main load on the SIS100 cryoplant. The FoS is capable to provide a field strength of 1.9 T. However, with sophisticated measurement systems slight distortions of the dipole field were detected. Those effects were tracked down to mechanical inaccuracies of the yoke proven by appropriate geometrical measurements and simulations. After a survey on alternative fabrication techniques a magnet with a new yoke was built with substantial changes to improve the mechanical accuracy. Its characteristics concerning cryogenic losses, cold geometry and the resulting magnetic-field quality are presented and an outlook on the series production of superconducting dipoles for SIS100 is given.

  17. Electromagnetic modes in cold magnetized strongly coupled plasmas

    OpenAIRE

    Tkachenko, I. M.; Ortner, J.; Rylyuk, V. M.

    1999-01-01

    The spectrum of electromagnetic waves propagating in a strongly coupled magnetized fully ionized hydrogen plasma is found. The ion motion and damping being neglected, the influence of the Coulomb coupling on the electromagnetic spectrum is analyzed.

  18. Exploring Dense and Cold QCD in Magnetic Fields

    CERN Document Server

    Ferrer, E J

    2016-01-01

    Strong magnetic fields are commonly generated in off-central relativistic heavy-ion collisions in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab and in the Large Hadron Collider at CERN and have been used to probe the topological configurations of the QCD vacua. A strong magnetic field can affect the character and location of the QCD critical point, influence the QCD phases, and lead to anomalous transport of charge. To take advantage of the magnetic field as a probe of QCD at higher baryon densities, we are going to need experiments capable to scan the lower energy region. In this context, the nuclotron-based ion collider facility (NICA) at JINR offers a unique opportunity to explore such a region and complement alternative programs at RHIC and other facilities. In this paper we discuss some relevant problems of the interplay between QCD and magnetic fields and the important role the experiments at NICA can play in tackling them.

  19. Exploring dense and cold QCD in magnetic fields

    Science.gov (United States)

    Ferrer, E. J.; de la Incera, V.

    2016-08-01

    Strong magnetic fields are commonly generated in off-central relativistic heavy-ion collisions in the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Lab and in the Large Hadron Collider at CERN and have been used to probe the topological configurations of the QCD vacua. A strong magnetic field can affect the character and location of the QCD critical point, influence the QCD phases, and lead to anomalous transport of charge. To take advantage of the magnetic field as a probe of QCD at higher baryon densities, we are going to need experiments capable to scan the lower energy region. In this context, the nuclotron-based ion collider facility (NICA) at JINR offers a unique opportunity to explore such a region and complement alternative programs at RHIC and other facilities. In this paper we discuss some relevant problems of the interplay between QCD and magnetic fields and the important role the experiments at NICA can play in tackling them.

  20. Transmittance properties in a magnetized cold plasma-superconductor periodic multilayer.

    Science.gov (United States)

    Aghajamali, Alireza

    2016-08-10

    This study theoretically investigates the transmittance properties of a one-dimensional photonic crystal containing magnetized cold plasma and high-temperature superconductor materials. The cutoff frequency, as a function of the magnetic field, electron density of the plasma layer, and temperature, will be investigated. The results illustrate that the temperature, electron density, and variations of the magnetic field affect the cutoff frequency. In addition, the shift trend in the cutoff frequency proves to be dependent on the polarization due to the presence of polarization-dependent magnetized cold plasma. Moreover, in temperature-dependent transmittance, weak oscillation and intensity can be seen at higher temperatures, which is in sharp contrast to low-temperature superconductor-dielectric structures. The proposed structure could certainly provide helpful information for the design of new types of antennas, reflectors, and high-pass filters at microwave frequency.

  1. Magnetic guide of cold atoms using a U-shaped current-carrying conductor

    Institute of Scientific and Technical Information of China (English)

    刘南春; 印建平

    2003-01-01

    We propose a new scheme to magnetically guide cold neutral atoms using a U-shaped current carrying conductor.The spatial magnetic field distribution from the U-shaped current-carrying conductor and the relationship between the magnetic field and parameters of the U-shaped conductor are analysed.Our study shows that U-shaped current-carrying conductor can be used to realize single-or double-channel magnetic guiding of cold atoms in weak-field-seeking states and to construct wrious atom-optical elements.By using Monte Carlo simulations,the dynamic process of the guided atomic-beam splitting in an atomic-beam splitter composed by the U-shaped current-carrying conductor is studied,and some results are presented.

  2. BEC-BCS crossover in a cold and magnetized two color NJL model

    CERN Document Server

    Duarte, Dyana C; Farias, R L S; Manso, Pedro H A; Ramos, Rudnei O; Scoccola, N N

    2016-01-01

    The BEC-BCS crossover for a NJL model with diquark interactions is studied in the presence of an external magnetic field. Particular attention is paid to different regularization schemes used in the literature. A thorough comparison of results is performed for the case of a cold and magnetized two-color NJL model. According to our results, the critical chemical potential for the BEC transition exhibits a clear inverse magnetic catalysis effect for magnetic fields in the range $ 1 \\lesssim eB/m_\\pi^2 \\lesssim 20 $. As for the BEC-BCS crossover, the corresponding critical chemical potential is very weakly sensitive to magnetic fields up to $eB \\sim 9\\ m_\\pi^2$, showing a much smaller inverse magnetic catalysis as compared to the BEC transition, and displays a strong magnetic catalysis from this point on.

  3. Double helix dipole design applied to magnetic resonance: a novel NMR coil.

    Science.gov (United States)

    Alonso, J; Soleilhavoup, A; Wong, A; Guiga, A; Sakellariou, D

    2013-10-01

    A new radio frequency coil design for NMR experiments is presented. The coil generates a magnetic field purely perpendicular to the longitudinal axis of the main magnet, and its sensitivity is higher than the traditional transversal resonators. This is achieved by adding the contribution of two tilted solenoid coils fed with opposite currents. The work presents the mathematical model for the new coil, numerical simulations performed to validate that model and a comparison with an equivalent saddle coil. The new design is tested experimentally in low- and high-field NMR experiments and compared with results obtained with equivalent saddle coils. The results lead to conclude that the new design provides better sensitivity than the transverse resonators commonly used in NMR. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. Braking of a magnetic dipole moving with an arbitrary velocity through a conducting pipe

    Energy Technology Data Exchange (ETDEWEB)

    Knyazev, B A; Kotel' nikov, Igor A [G.I. Budker Institute of Nuclear Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation); Tyutin, A A; Cherkasskii, Valerii S [Department of Physics, Novosibirsk State University, Novosibirsk (Russian Federation)

    2006-09-30

    Lectures introducing students to electromagnetic induction phenomena often feature the popular experiment in which a small magnet falling down a long conducting pipe is markedly decelerated by the retarding force due to Foucault eddy currents arising in the pipe. In this paper, a formula for the retarding force, valid both for low velocities (when the force is proportional to the velocity v of magnet motion) and high velocities (when it first decreases as v{sup -1} and then as v{sup -1/2}), is derived. The last two regimes are analogous to the collisionless (and hence unbounded) acceleration of plasma electrons and have not been previously described in the literature. The calculation of the retarding force in the presence of a longitudinal cut in the pipe wall is carried out, and experiments to measure this force are discussed. (methodological notes)

  5. A prototype of the LHC dipole magnet, with the two beampipes running through the centre.

    CERN Multimedia

    Laurent Guiraud

    1997-01-01

    CERN scientists conceived of their next collider as a "high-luminosity" machine that would excel at producing a high number of collisions. But since making a strong antiproton beam is laborious, this collider would have to smash together two proton beams. Since the LHC would use two proton beams running in opposite directions, it required two sets of magnets-a "two-in-one" collider.

  6. Electric field control of magnetic states in isolated and dipole-coupled FeGa nanomagnets delineated on a PMN-PT substrate

    Science.gov (United States)

    Ahmad, Hasnain; Atulasimha, Jayasimha; Bandyopadhyay, Supriyo

    2015-10-01

    We report observation of a ‘non-volatile’ converse magneto-electric effect in elliptical FeGa nanomagnets delineated on a piezoelectric PMN-PT substrate. The nanomagnets are first magnetized with a magnetic field directed along their nominal major axes. Subsequent application of a strong electric field across the piezoelectric substrate generates strain in the substrate, which is partially transferred to the nanomagnets and rotates the magnetizations of some of them away from their initial orientations. The rotated magnetizations remain in their new orientations after the field is removed, resulting in ‘non-volatility’. In isolated nanomagnets, the magnetization rotates by \\lt 90^\\circ upon application of the electric field, but in a dipole-coupled pair consisting of one ‘hard’ and one ‘soft’ nanomagnet, which are both initially magnetized in the same direction by the magnetic field, the soft nanomagnet’s magnetization rotates by \\gt 90^\\circ upon application of the electric field because of the dipole influence of the hard nanomagnet. This effect can be utilized for a nanomagnetic NOT logic gate.

  7. Three-stage linear, split-Stirling cryocooler for 1 to 2K magnetic cold stage

    Science.gov (United States)

    Longsworth, R. C.

    1993-01-01

    A long-life, linear, high efficiency 8K split Stirling cycle cryocooler was designed, built, and tested. The refrigerator is designed for cooling a 50 mW, 1.5K magnetic cold stage. Dual opposed piston compressors are driven by moving-coil linear motors. The three stage expander, although not completed, is also driven by a linear motor and is designed to produce 1 SW at 60K, 4W at 16K, and 1.2W at 8K. The cold regenerator employs a parallel gap construction for high efficiency. The key technology areas addressed include warm and cold flexible suspension bearings and a new cold regenerator geometry for high efficiency at 8K.

  8. Cold and Dense Matter in a Magnetic Field

    CERN Document Server

    de la Incera, Vivian

    2009-01-01

    Our Universe is full of regions where extreme physical conditions are realized. Among the most intriguing cases are the so-called magnetars: neutron stars with very dense cores and super-strong magnetic fields. In this paper I review the current understanding of the physical properties of quark matter at ultra-high density in the presence of very large magnetic fields. I will discuss the main results on this topic, the main challenges that still remain, and how they could be related to the physics of magnetars.

  9. On the Use of Wavelet Transform for Quench Precursors Characterisation in the LHC Superconducting Dipole Magnets

    CERN Document Server

    Calvi, M; Bottura, L; Masi, A; Siemko, A

    2006-01-01

    Premature training quenches are caused by transient energy released within the magnet coil while it is energized. Signals recorded across the so-called quench antenna carry information about these disturbances. A new method for identifying and characterizing those events is proposed, which applies the wavelet transform approach to the recorded signals. Such an approach takes into account the time of occurrence as well as frequency content of the events. The choice of the optimal mother wavelet is discussed, and the results obtained from the application of the method to actual signals are given. The criteria to recognize the interesting events are presented as well as the methodology to classify their global behavior.

  10. By 7 March, a total of 616 magnets had been delivered, meaning the delivery of half the superconducting dipole magnets

    CERN Multimedia

    Maximilien Brice

    2005-01-01

    The teams in charge of the LHC magnets with the panel testifying to the delivery of the 616th magnet. In the first row, seated, from left to right: C. Bosteels, AT-MAS group secretary, R. Aymar, Director-General, L. Rossi, Head of the AT-MAS group, L. Evans, LHC Project Leader, P. Lebrun, Head of the AT Department, W. Scandale , Deputy Head of the AT-MAS group and J.-P. Koutchouk, Head of the AT-MAS Analysis Section.

  11. Electric quadrupole and magnetic dipole moments of odd nuclei near the magic ones in a self-consistent approach

    CERN Document Server

    Co', G; Anguiano, M; Bernard, R N; Lallena, A M

    2015-01-01

    We present a model which describes the properties of odd-even nuclei with one nucleon more, or less, with respect to the magic number. In addition to the effects related to the unpaired nucleon, we consider those produced by the excitation of the closed shell core. By using a single particle basis generated with Hartree-Fock calculations, we describe the polarization of the doubly magic-core with Random Phase Approximation collective wave functions. In every step of the calculation, and for all the nuclei considered, we use the same finite-range nucleon-nucleon interaction. We apply our model to the evaluation of electric quadrupole and magnetic dipole moments of odd-even nuclei around oxygen, calcium, zirconium, tin and lead isotopes. Our Random Phase Approximation description of the polarization of the core improves the agreement with experimental data with respect to the predictions of the independent particle model. We compare our results with those obtained in first-order perturbation theory, with those ...

  12. Critical behavior of isotropic three-dimensional systems with dipole-dipole interactions

    Energy Technology Data Exchange (ETDEWEB)

    Belim, S. M., E-mail: sbelim@mail.ru [Dostoevsky Omsk State University (Russian Federation)

    2013-06-15

    The critical behavior of Heisenberg magnets with dipole-dipole interactions near the line of second-order phase transitions directly in three-dimensional space is investigated in terms of a field-theoretic approach. The dependences of critical exponents on the dipole-dipole interaction parameter are derived. Comparison with experimental facts is made.

  13. By 7 March, a total of 616 magnets had been delivered, meaning the delivery of half the superconducting dipole magnets

    CERN Multimedia

    maximilien Brice

    2005-01-01

    This is a remarkable achievement bearing in mind the difficulties involved in the move from the prototyping and pre-series phase to large-scale series production. Lucio Rossi, Head of the AT-MAS group, which is in charge of the production of the main magnets, celebrated this achievement with his team at a small get-together on Tuesday, 8 March.

  14. $H \\rightarrow \\tau^+ \\tau^- \\gamma$ as a Probe of the $\\tau$ Magnetic Dipole Moment

    CERN Document Server

    Galon, Iftah; Tait, Tim M P

    2016-01-01

    Low energy observables involving the Standard Model fermions which are chirality-violating, such as anomalous electromagnetic moments, necessarily involve an insertion of the Higgs in order to maintain $SU(2) \\times U(1)$ gauge invariance. As the result, the properties of the Higgs boson measured at the LHC impact our understanding of the associated low-energy quantities. We illustrate this feature with a discussion of the electromagnetic moments of the $\\tau$-lepton, as probed by the rare decay $H \\rightarrow \\tau^+ \\tau^- \\gamma$. We assess the feasibility of measuring this decay at the LHC, and show that the current bounds from lower energy measurements imply that $13~\\rm{TeV}$ running is very likely to improve our understanding of new physics contributing to the anomalous magnetic moment of the tau.

  15. Spin polarization effects on magnetic dipole moment of 153,155Eu

    Science.gov (United States)

    Hoşgör, Gamze; Yakut, Hakan; Tabar, Emre

    2017-02-01

    Using the Quasiparticle Phonon Nuclear Model (QPNM) and taking into account the spin-spin interaction the effects of the spin polarization on the intrinsic magnetic moments (gK) of 153-155Eu isotopes have been studied. Our calculations indicated that because of the spin polarization, the spin gyromagnetic factors (gs) of the nucleons in the nucleus reduce noticeable from its free nucleon value and the spin-spin interactions play an important role in the renormalization (gse f f .) of the gs factors. A very good reproduction of the phenomenological quenching of gs factor from its free values (gse f f≅0.6 -0.7 gsf r e e) is obtained. The calculated values of effective gse f f and gK are also in fair agreementwith the experiment data.

  16. Gain Enhanced On-Chip Folded Dipole Antenna Utilizing Artificial Magnetic Conductor at 94 GHz

    KAUST Repository

    Nafe, Mahmoud

    2017-09-05

    On-chip antennas suffer from low gain values and distorted radiation patterns due to lossy and high permittivity Si substrate. An ideal solution would be to isolate the lossy Si substrate from the antenna through a Perfect Electric Conductor (PEC) ground plane, however the typical CMOS stack up which has multiple metal layers embedded in a thin oxide layer does not permit this. In this work, an Artificial Magnetic Conductor (AMC) reflecting surface has been utilized to isolate the Si substrate from the antenna. Contrary to the previous reports, the AMC structure is completely embedded in the thin oxide layer with the ground plane above the Si substrate. In this approach, the AMC surface acts for the first time as both a reflector and a silicon shield. As a result the antenna radiation pattern is not distorted and its gain is improved by 8 dB. The fabricated prototype demonstrates good impedance and radiation characteristics.

  17. Development of a compact magnetic resonance imaging system for a cold room

    Science.gov (United States)

    Adachi, Satoru; Ozeki, Toshihiro; Shigeki, Ryosuke; Handa, Shinya; Kose, Katsumi; Haishi, Tomoyuki; Aoki, Masaaki

    2009-05-01

    A compact magnetic resonance imaging (MRI) system for a cold (-5 °C) room has been developed to acquire MR images below the freezing point of water. The MRI system consists of a 1.0 T permanent magnet, a higher-order shim coil set, and a gradient coil probe, installed in the cold room, and a compact MRI console installed in a room at normal temperature (20-25 °C). The most difficult problem for the installation of the MRI system in the cold room was the degradation of the field homogeneity of the permanent magnet shimmed at 25 °C. To overcome this problem, higher-order shim coils were developed and the temperature variation of the magnetic field distribution was measured using a standard phantom with and without shim coil currents. As a result, it was confirmed that the homogeneity (the difference between the minimum and maximum values) of the magnetic field in the 17×17×19 mm3 rectangular parallelepiped region was improved from 117 to 59 ppm using an appropriate combination of shim coil currents. A snowpack immersed in dodecane (C12H26) was imaged using a driven-equilibrium three-dimensional (3D) spin-echo sequence at -5 °C. The visualized 3D structure of the snowpack demonstrated the effectiveness of our approach.

  18. Automatic compensation of magnetic field for a rubidium space cold atom clock

    Science.gov (United States)

    Lin, Li; Jingwei, Ji; Wei, Ren; Xin, Zhao; Xiangkai, Peng; Jingfeng, Xiang; Desheng, Lü; Liang, Liu

    2016-07-01

    When the cold atom clock operates in microgravity around the near-earth orbit, its performance will be affected by the fluctuation of magnetic field. A strategy is proposed to suppress the fluctuation of magnetic field by additional coils, whose current is changed accordingly to compensate the magnetic fluctuation by the linear and incremental compensation. The flight model of the cold atom clock is tested in a simulated orbital magnetic environment and the magnetic field fluctuation in the Ramsey cavity is reduced from 17 nT to 2 nT, which implied the uncertainty due to the second order Zeeman shift is reduced to be less than 2×10-16. In addition, utilizing the compensation, the magnetic field in the trapping zone can be suppressed from 7.5 μT to less than 0.3 μT to meet the magnetic field requirement of polarization gradients cooling of atoms. Project supported by the Ministry of Science and Technology of China (Grant No. 2013YQ09094304), the Youth Innovation Promotion Association, Chinese Academy of Sciences, and the National Natural Science Foundation of China (Grant Nos. 11034008 and 11274324).

  19. Proposal for the award of three contracts for the supply of the tooling for production lines for the coils of the LHC dipole magnets

    CERN Document Server

    2000-01-01

    This document concerns the award of three contracts, each for the supply of the tooling for a production line for the coils of the LHC dipole magnets. This equipment is to be installed at the premises of the consortium and of the two firms which are currently each producing 30 pre-series LHC dipole magnets. For the reasons outlined in this document, the Finance Committee is invited to agree to the negotiation of three contracts, each for the supply of the tooling for an additional production line for the coils of the LHC dipole magnets, with: - the consortium ALSTOM ENERGIE (FR) - JEUMONT INDUSTRIE (FR) for a total amount of 2 049 600 euros (3 146 136 Swiss francs), not subject to revision; - ANSALDO ENERGIA (IT) for a total amount of 2 132 804 euros (3 273 854 Swiss francs), not subject to revision; - NOELL-KRC ENERGIE UND UMWELTTECHNIK (DE) for a total amount of 1 988 365 euros (3 052 140 Swiss francs), not subject to revision. The rates of exchange which have been used are those stipulated in the tenders. ...

  20. Design of a Cosine-theta Dipole Magnet Wound with Coated Conductors Considering their Deformation at Coil ends During Winding Process

    Science.gov (United States)

    Amemiya, Naoyuki; Miyahara, Hidetoshi; Ogitsu, Toru; Kurusu, Tsutomu

    By using differential geometry, we modeled the three-dimensional shapes of the coil ends of cosine-theta magnets while considering local edge-wise bend, local flat-wise bend, and torsion of coated conductors. We focus on the feasibility of winding coil ends against the stress caused by bending. We discussed the feasibility of winding based on two assumptions to form coil ends: all turns of coated conductors are free from edge-wise bend; faces of all turns of coated conductors are completely parallel. Using the first assumption, we designed a cosine-theta dipole magnet wound with coated conductors.

  1. Magnet properties of Mn{sub 70}Ga{sub 30} prepared by cold rolling and magnetic field annealing

    Energy Technology Data Exchange (ETDEWEB)

    Ener, Semih, E-mail: ener@fm.tu-darmstadt.de [Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Skokov, Konstantin P. [Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Karpenkov, Dmitriy Yu. [Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Faculty of Physics, Tver State University, 170100 Tver (Russian Federation); Immanuel Kant Baltic Federal University, 236041 Kaliningrad (Russian Federation); Kuz' min, Michael D. [Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Gutfleisch, Oliver [Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Fraunhofer IWKS, Project Group for Material Cycles and Resource Strategy, 63457 Hanau (Germany)

    2015-05-15

    The remanence and coercivity of arc melted Mn{sub 70}Ga{sub 30} can be substantially improved by cold rolling. For best performance the rolled material should be annealed at T=730 K in the presence of a magnetic field of 1 T. The so-obtained magnet has a remanence of 0.239 T and a coercivity of 1.24 T at room temperature. The underlying reason for the high coercivity and remanence is the increase of the content of a metastable ferrimagnetic D0{sub 22} phase at the expense of the normally stable anti-ferromagnetic D0{sub 19}. Magnetic field significantly increases the nucleation rate of the ferromagnetic D0{sub 22} phase that leads to grain size refinement and as a consequence of improving remanence and coercive field. - Highlights: • Alternative synthesis method for D0{sub 22} phase formation in Mn–Ga is developed. • Effect of cold rolling and annealing on magnetic properties of Mn{sub 70}Ga{sub 30} is examined. • Small magnetic fields are sufficient to accelerate nucleation of the D0{sub 22} phase.

  2. Influence of cold drawing on the magnetic properties and giant magneto-impedance response of FINEMET nanocrystalline wires

    Science.gov (United States)

    Chiriac, H.; Corodeanu, S.; Donac, A.; Dobrea, V.; Ababei, G.; Stoian, G.; Lostun, M.; Óvári, T.-A.; Lupu, N.

    2015-05-01

    The effect of annealing and applied stresses on the magnetic properties and giant magneto-impedance effect in as-cast and cold drawn FINEMET wires has been studied. The results show major changes in the evolution of the magnetic permeability, coercivity, and magneto-impedance response with the annealing and cold drawing stages. These changes have been explained considering the structural transformations, intrinsic, applied, and drawing-induced stresses, as well as their effect on the global magnetostriction of the wires. The observed sensitivity to applied stresses recommends this class of cold drawn nanocrystalline wires for applications in miniaturized magnetic sensors with enhanced sensitivity.

  3. EFFECTS OF MAGNETIC FIELD STRENGTH ON MICROSTRUCTURE AND TEXTURE EVOLUTION IN COLD-ROLLED INTERSTITIAL-FREE STEEL BY MAGNETIC FIELD ANNEALING

    Institute of Scientific and Technical Information of China (English)

    Y. Wu; C.S. He; X. Zhao; L. Zuo; T. Watanabe

    2008-01-01

    Effects of magnetic field strength on the evolution of recrystallization microstructure and recrystallization texture in cold-rolled interstitial-free steel were investigated after annealing at 660°C in a magnetic field up to 12 T. Magnetic annealing was found to retard recrystallization and induce recrystallized grains elongated along the magnetic field direction. An interesting phenomenon is that the magnetic field shows the strongest effect at 1 T.

  4. Degenerate mixing of plasma waves on cold, magnetized single-species plasmas

    Science.gov (United States)

    Anderson, M. W.; O'Neil, T. M.; Dubin, D. H. E.; Gould, R. W.

    2011-10-01

    In the cold-fluid dispersion relation ω =ωp/[1+(k⊥/kz)2]1/2 for Trivelpiece-Gould waves on an infinitely long magnetized plasma cylinder, the transverse and axial wavenumbers appear only in the combination k⊥/kz. As a result, for any frequency ω Dubin modes), a perturbation analysis is used to investigate the mixing of low-order, nearly degenerate Dubin modes caused by small deformations of a plasma spheroid.

  5. Measurement of the magnetic moment in a cold worked 304 stainless steel using HTS SQUID

    Energy Technology Data Exchange (ETDEWEB)

    Park, D.G. [Korea Atomic Energy Research Institute, Yusung P.O. Box 105, Taejon 305-600 (Korea, Republic of)], E-mail: dwkim1@kaeri.re.kr; Kim, D.W.; Angani, C.S. [Korea Atomic Energy Research Institute, Yusung P.O. Box 105, Taejon 305-600 (Korea, Republic of); Timofeev, V.P. [B. Verkin Institute for Low Temperature Physics and Engineering, National Academy of Science of Ukraine, 47 Lenin Ave, Kharkov 61103 (Ukraine); Cheong, Y.M. [Korea Atomic Energy Research Institute, Yusung P.O. Box 105, Taejon 305-600 (Korea, Republic of)

    2008-10-15

    The magnetic properties of stainless steel have been investigated using a radio frequency (RF) high-temperature superconductivity (HTS) SQUID (Superconducting QUantum Interference Device)-based susceptometer. The nuclear grade 304 stainless steel is nonmagnetic at a normal condition but it changes to a partially ferromagnetic state associated with martensitic transformation under a plastic deformation. The magnetic moment of the 304 stainless steels was increased with an increasing cold work rate, and decreased with an increasing annealing temperature. The change of mechanical properties such as yield strength and ultimate tensile strength (UTS) are also analyzed in terms of deformation-induced martensitic transformation.

  6. Arrays of microscopic magnetic traps for cold atoms and their applications in atom optics

    Institute of Scientific and Technical Information of China (English)

    印建平; 高伟建; 胡建军

    2002-01-01

    A single microscopic magnetic trap for neutral atoms using planar current-carrying wires was proposed and studiedtheoretically by Weinstein et al. In this paper, we propose three structures of composite current-carrying wires to provide1D, 2D and 3D arrays of microscopic magnetic traps for cold alkali atoms. The spatial distributions of magnetic fieldsgenerated by these structures are calculated and the field gradient and curvature in each single microtrap are analysed.Our study shows that arrays of microscopic magnetic traps can be used to provide 1D, 2D or 3D atomic magneticlattices, and even to realize 1D, 2D and 3D arrays of magneto-optical traps, and so on.

  7. Uniform synthetic magnetic field and effective mass for cold atoms in a shaken optical lattice.

    Science.gov (United States)

    Sols, Fernando; Creffield, Charles E.; Pieplow, Gregor; Goldman, Nathan

    2016-05-01

    Cold atoms can be made to experience synthetic magnetic fields when placed in a suitably driven optical lattice. For coherent systems the switching protocol plays an essential role in determining the long time behavior. Relatively simple driving schemes may generate a uniform magnetic flux but an inhomogeneous effective mass. A two-stage split driving scheme can recover a uniform effective mass but at the price of rendering the magnetic field space dependent. We propose a four-stage split driving that generates uniform field and mass of arbitrary values for all driving amplitudes. Finally, we study a modified two-stage split driving approach that enables uniform field and mass for most of but not all values of the magnetic field. Work supported by MINECO (Spain) under Grant FIS2013-41716-P, by FRS-FNRS (Belgium), and by BSPO under PAI Project No. P7/18 DYGEST.

  8. Quasistatic dipole in magnetized plasma in resonance frequency band. Response of the receiving antenna, and charge distribution on the antenna wire

    Science.gov (United States)

    Chugunov, Yu. V.; Shirokov, E. A.

    2016-05-01

    The paper discusses issues related to the radiation and reception of quasi-electrostatic waves by short antennas in resonance conditions (in the whistler range) in magnetized plasma. First, the response of the receiving antenna on the incident field of slow quasipotential waves is analyzed. It made it possible to explain in detail the results of the two-point rocket experiment OEDIPUS-C in the Earth's ionosphere. Second, the problem of the charge distribution along the short transmission (reception) dipole antenna is considered. The corresponding integral equation is obtained and solved analytically. The impedance of the antenna is found. It is shown that in the majority of cases, charge distribution along the dipole length can be considered constant.

  9. The SMC (Short Model Coil) dipole: An R&D program for Nb3Sn accelerator magnets

    CERN Document Server

    Perez, J C; Bordini, B; Canfer, S; Ellwood, G; Feuvrier, J; Guinchard, M; Karppinen, M; Kokkinos, C; Manil, P; Milanese, A; Oberli, L; Regis, F; de Rijk, G

    2012-01-01

    The Short Model Coil (SMC) assembly has been designed, as test bench for short racetrack coils wound with Nb3Sn cable. The mechanical structure comprises an iron yoke surrounded by a 20 mm thick aluminium alloy shell, and includes four loading pads that transmit the required pre-compression from the outer shell into the two coils. The outer shell is pre-tensioned with mechanical keys that are inserted with the help of pressurized bladders and two 30 mm diameter aluminium alloy rods provide the axial loading to the coil ends. The outer shell, the axial rods, and the coils are instrumented with strain gauges, which allow precise monitoring of the loading conditions during the assembly and at cryogenic temperature during the magnet test. Two SMC assemblies have been completed and cold tested in the frame of a European collaboration between CEA (FR), CERN and STFC (UK) and with the technical support from LBNL (US). This paper describes the main features of the SMC assembly, the experience from the dummy assembli...

  10. The Short Model Coil (SMC) dipole: an R&D program towards Nb3Sn accelerator magnets

    CERN Document Server

    Bajko, M; Canfer, S; Ellwood, G; Feuvrier, J; Guinchard, M; Karppinen, M; Kokkinos, C; Manil, P; Milanese, A; Oberli, L; Perez, J-C; Regis, F; de Rijk, G

    2011-01-01

    The Short Model Coil (SMC) assembly has been designed, as test bench for short racetrack coils wound with Nb3Sn cable. The mechanical structure comprises an iron yoke surrounded by a 20 mm thick aluminium alloy shell, and includes four loading pads that transmit the required pre-compression from the outer shell into the two coils. The outer shell is pre-tensioned with mechanical keys that are inserted with the help of pressurized bladders and two 30 mm diameter aluminium alloy rods provide the axial loading to the coil ends. The outer shell, the axial rods, and the coils are instrumented with strain gauges, which allow precise monitoring of the loading conditions during the assembly and at cryogenic temperature during the magnet test. Two SMC assemblies have been completed and cold tested in the frame of a European collaboration between CEA (FR), CERN and STFC (UK) and with the technical support from LBNL (US). This paper describes the main features of the SMC assembly, the experience from the dummy assemblie...

  11. Status Report on the LHC Main Magnet Production

    CERN Document Server

    de Rijk, G; Cornelis, M; Durante, M; Fessia, P; Miles, J; Modena, M; Molinari, G; Rinn, J; Savary, F; Schirm, K; Simon, F; Tommasini, D; Tortschanoff, Theodor; Vlogaert, J; Applied Superconductivity Conference (ASC/04)

    2005-01-01

    The LHC ring will contain 1232 main dipole and 382 main quadrupole twin aperture magnets. All main magnets are superconducting and employ NbTi/Cu Rutherford type cables operated at 1.9 K. The dipole production has reached the equivalent of almost three octants of cold masses and nearly four octants of collared coils. The quadrupole production has reached 75 cold masses and over 150 bare magnets. The ramping up of large scale magnet production has posed several challenges which will be discussed, like: the coil size uniformity, coil pre-stress control, cold mass welding technique and the geometrical shape issues. The magnetic measurement results at warm will be presented together with their usage for the quality control in the production. The common features and differences of the three dipole producers will be discussed. Finally the latest version of the production schedule will be presented.

  12. The scissors mode and other magnetic and electric dipole excitations in the transitional nuclei {sup 178,180}Hf

    Energy Technology Data Exchange (ETDEWEB)

    Pietralla, N. [Koeln Univ. (Germany). Inst. fuer Kernphysik; Beck, O. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Besserer, J. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Brentano, P. von [Koeln Univ. (Germany). Inst. fuer Kernphysik; Eckert, T. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Fischer, R. [Koeln Univ. (Germany). Inst. fuer Kernphysik; Fransen, C. [Koeln Univ. (Germany). Inst. fuer Kernphysik; Herzberg, R.-D. [Koeln Univ. (Germany). Inst. fuer Kernphysik; Jaeger, D. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Jolos, R.V. [Koeln Univ. (Germany). Inst. fuer Kernphysik]|[Bogoliubov Theoretical Laboratory, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Kneissl, U. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Krischok, B. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Margraf, J. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Maser, H. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Nord, A. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Pitz, H.H. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Rittner, M. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Schiller, A. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Zilges, A. [Koeln Univ. (Germany). Inst. fuer Kernphysik]|[WNSL, Yale University, P.O. Box 208124, New Haven, CT 06520-8124 (United States)

    1997-05-26

    Photon scattering experiments have been performed on the heavy deformed nuclei {sup 178,180}Hf using an E{sub {gamma}}<4 MeV bremsstrahlung beam as a continuous energy photon source. Numerous dipole excitations have been identified from the spectra of high-resolution Ge {gamma} detectors. Spins, K quantum numbers, dipole excitation strengths, and level widths, have been extracted from the scattering cross sections. From the measured level widths lifetimes of 67 levels can be deduced. The excitation strength of the scissor mode is discussed and extends the systematics from the neighboring rare earth nuclei. Besides the {Delta}K=1 excitations other dipole excitations have been observed that are distinguished from the scissor mode states by their different decay behavior. (orig.).

  13. The effects of magnetic fields in cold clouds in cooling flows

    Science.gov (United States)

    Friaça, A. C. S.; Jafelice, L. C.

    1999-01-01

    Large masses of absorbing material are inferred to exist in cooling flows in clusters of galaxies from the excess X-ray absorption in the spectra of some X-ray clusters. The absorbing material is probably in the form of cold clouds pressure-confined by the surrounding, hot, X-ray-emitting gas. The cold clouds could remain relatively static until they are destroyed by evaporation or ablation, or give rise to star formation. If the final fate of the clouds is stars, the initial mass function (IMF) of the stars formed over the whole cooling-flow region (r~ 100 kpc) should be biased to low masses, to avoid a very luminous, blue halo for the central galaxy of the cooling flow. However, there is evidence for bright star formation in the innermost (rJeans mass, in establishing a natural mass-scale for star formation. When this new mass-scale is taken into account, we obtain the right variation of the biasing of the IMF with the radius in addition to inhibition of high-mass star formation at large radii. We also demonstrate that magnetic reconnection is a more efficient mechanism than ambipolar diffusion to remove magnetic fields in cold clouds.

  14. Accumulation and thermalization of cold atoms in a finite-depth magnetic trap

    CERN Document Server

    Chicireanu, R; Gorceix, O; Keller, J C; Laburthe-Tolra, B; Marechal, E; Porto, J V; Pouderous, A; Vernac, L

    2006-01-01

    We experimentally and theoretically study the continuous accumulation of cold atoms from a magneto-optical trap (MOT) into a finite depth trap, consisting in a magnetic quadrupole trap dressed by a radiofrequency (RF) field. Chromium atoms (52 isotope) in a MOT are continuously optically pumped by the MOT lasers to metastable dark states. In presence of a RF field, the temperature of the metastable atoms that remain magnetically trapped can be as low as 25 microK, with a density of 10^17 atoms.m-3, resulting in an increase of the phase-space density, still limited to 7.10^-6 by inelastic collisions. To investigate the thermalization issues in the truncated trap, we measure the free evaporation rate in the RF-truncated magnetic trap, and deduce the average elastic cross section for atoms in the 5D4 metastable states, equal to 7.0 10^-16m2.

  15. LHC Magnet Assembly Facility in building 181

    CERN Multimedia

    CERN Video Productions

    2005-01-01

    Hall 181 activities for the LHC machine * Reception of the American magnets : quadrupoles and separation dipoles * Assembly of the string Low-Beta Triplet -Q2-Q3-DFBX-D1 * Insertion quadrupoles cold masses assembly * Magnets reception type MQM, MQY, MCBC et MCBY * Assembly in the shell * Longitudinal welding under the press * Equipment with end covers in the finishing area

  16. The reaction $\\gamma p \\to \\pi^\\circ \\gamma^\\prime p$ and the magnetic dipole moment of the $\\Delta^+(1232)$ resonance

    CERN Document Server

    Kotulla, M; Annand, J R M; Beck, R; Caselotti, G; Fog, L S; Hornidge, D; Janssen, S; Krusche, B; McGeorge, J C; McGregor, I J D; Mengel, K; Messchendorp, J G; Metag, V; Novotny, R; Pfeiffer, M; Rost, M; Sack, S; Sanderson, R; Schadmand, S; Watts, D P

    2002-01-01

    The reaction $\\gamma p \\to \\pi^\\circ \\gamma^\\prime p$ has been measured with the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI for energies between $\\sqrt{s}$ = 1221--1331 MeV. Cross sections differential in angle and energy have been determined for all particles in the final state in three bins of the excitation energy. This reaction channel provides access to the magnetic dipole moment of the $\\Delta^{+}(1232)$ resonance and, for the first time, a value of $\\mu_{\\Delta^+} = (2.7_{-1.3}^{+1.0}(stat.) \\pm 1.5 (syst.) \\pm 3(theo.)) \\mu_N$ has been extracted.

  17. ALICE dipole and decoration

    CERN Multimedia

    Maximilien Brice

    2004-01-01

    The ALICE cavern receives a painting made specially to mark the 50th anniversary of CERN that is mounted on the L3 solenoid magnet, reused from the LEP experiment that ran from 1989 to 2000. The dipole, which is cooled by demineralised water, will bend the path of muons that leave the huge rectangular solenoid. These muons are heavy electrons that interact less with matter allowing them to be studied at large distances from the interaction point.

  18. Cold atom trap with zero residual magnetic field: the ac magneto-optical trap.

    Science.gov (United States)

    Harvey, Matthew; Murray, Andrew James

    2008-10-24

    A novel atom trap is described using alternating current to generate the magnetic B field, together with high speed polarization switching of the damping laser field. This combination produces a trap as effective as a standard magneto-optical trap (MOT), with the advantage that the average B field is zero. No net current is hence induced in surrounding conductive elements, and the B field produced by the ac MOT is found to switch off >300 times faster than a conventional MOT. New experiments can hence be performed, including charged particle probing or detection of the cold target ensemble.

  19. Confinement of ultra-cold neutron in a multiple cusp magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Akiyama, Nobumichi; Inoue, Nobuyuki; Nihei, Hitoshi; Kinosita, Ken-ichi [Tokyo Univ. (Japan). Faculty of Engineering

    1996-08-01

    A new confinement system of ultra-cold neutrons is proposed. The neutron bottle is made of a rectangular vacuum chamber with the size of 40 cm x 40 cm x 30 cm covered with arrays of bar type permanent magnets. The operation of bottle requires neither cooling system nor high electric power supply, and thereby the bottle is appropriate to use in the room which is located in controlled area. The maximum kinetic energy of neutrons confined is 20 neV. Experimental scheme to test the performance of the bottle is described. (author)

  20. Phase structure of cold magnetized quark matter within the SU(3) NJL model

    CERN Document Server

    Grunfeld, A G; Pinto, M B; Scoccola, N N

    2014-01-01

    The possible different phases of cold quark matter in the presence of a finite magnetic field and chemical potential are obtained within the SU(3) NJL model for two parameter sets often used in the literature. Although the general pattern is the same in both cases, the number of intermediate phases is parameter dependent. The chiral susceptibilities, as usually defined, are different not only for the s-quark as compared with the two light quarks, but also for the u and d-quarks, yielding non identical crossover lines for the light quark sector.

  1. Evolution of magnetic phase at low aging temperature in a heavily cold-drawn stainless steel fiber

    Science.gov (United States)

    Yang, Shun-Tung; Hwang, Weng-Sing; Shyr, Tien-Wei; Cheng, I.-Lin

    2012-08-01

    The evolution of the magnetic phase upon aging at 300-520 °C in a heavily cold-drawn AISI 316L austenitic stainless steel fiber was studied using thermomagnetic analysis (TMA) and magnetic force microscopy with a heating stage. An increasing trend of magnetization from 50 °C to around 470 °C in the heating curves of TMA in austenitic stainless steels after a cold-drawing process was observed. No significant Ms temperature signal in the TMA curve at cooling indicated an increase in magnetization upon cooling period without significant phase transformation. A series of in situ magnetic force microscopy observations reveal a growth of the magnetic domain structure after aging at 300 °C for 2.5 h. Results show that the ferromagnetic increase during aging at lower annealing temperature resulted from the growth of martensite.

  2. Observation of the Forbidden Magnetic Dipole Transition 6{sup 2}P{sub ½} --> 7{sup 2}P{sub ½} in Atomic Thallium

    Science.gov (United States)

    Chu, S.

    1976-10-01

    A measurement of the 6{sup 2}P{sub ½} --> 7{sup 2}P{sub ½} forbidden magnetic dipole matrix element in atomic thallium is described. A pulsed, linearly polarized dye laser tuned to the transition frequency is used to excite the thallium vapor from the 6{sup 2}P{sub ½} ground state to the 7{sup 2}P{sub ½} excited state. Interference between the magnetic dipole M1 amplitude and a static electric field induced E1 amplitude results in an atomic polarization of the 7{sup 2}P{sub ½} state, and the subsequent circular polarization of 535 nm fluorescence. The circular polarization is seen to be proportional to / as expected, and measured for several transitions between hyperfine levels of the 6{sup 2}P{sub ½} and 7{sup 2}P{sub ½} states. The result is = -(2.11 +- 0.30) x 10{sup -5} parallel bar e parallel bar dirac constant/2mc, in agreement with theory.

  3. Proposal for the award of a contract for the supply of austenitic steel strips for collars of the LHC superconducting dipole magnets

    CERN Document Server

    1999-01-01

    This document concerns the award of a contract for the supply of 410 mm-wide austenitic steel strips for the collars of the LHC superconducting dipole magnets. Following a market survey carried out among 39 firms in twelve Member States and two firms in Japan, a call for tenders (IT-2618/LHC/LHC) was sent on 3 June 1999 to five firms in four Member States and two firms in Japan. The Council agreed to the Management?s proposal to invite Japanese industry to participate, where appropriate, in calls for tenders for supplies for the LHC Project (CERN/CC/2110). By the closing date, CERN had received six tenders. The Finance Committee is invited to approve the negotiation of a contract with the firm NIPPON STEEL CORPORATION (JP) for the supply of 11 000 tonnes of 410 mm-wide austenitic steel strips for the collars of the LHC superconducting dipole magnets for a total amount of 4 298 943 000 Japanese yen, subject to revision for contractual deliveries after 31 December 2000, with an option for the supply of up to 10...

  4. Fermion Dipole Moment and Holography

    CERN Document Server

    Kulaxizi, Manuela

    2015-01-01

    In the background of a charged AdS black hole, we consider a Dirac particle endowed with an arbitrary magnetic dipole moment. For non-zero charge and dipole coupling of the bulk fermion, we find that the dual boundary theory can be plagued with superluminal modes. Requiring consistency of the dual CFT amounts to constraining the strength of the dipole coupling by an upper bound. We briefly discuss the implications of our results for the physics of holographic non-Fermi liquids.

  5. Change in magnetic properties of a cold rolled and thermally aged Fe-Cu alloy

    Science.gov (United States)

    Park, D. G.; Ryu, K. S.; Kobayashi, S.; Takahashi, S.; Cheong, Y. M.

    2010-05-01

    The variation in magnetic properties of a Fe-1%Cu model alloy due to a cold rolling and a thermal aging has been evaluated to simulate the radiation damage of reactor pressure vessel of nuclear power plant. The thermal aging was conducted at 500 °C with different aging times in series. The hysteresis loops, magnetic Barkhausen noise (BN) and Vickers microhardness were measured for prestrained, strained, and thermal aged samples. The coercivity increased by a plastic strain and decreased by thermal aging, The BN decreased in the prestrained and strained samples but large changes were observed in the strained sample. These results were interpreted in terms of the domain wall motion signified by a change in the mean free path associated with microinternal stress and copper rich precipitates.

  6. Magnetization as a critical defining parameter for strand in precision dipole applications implications for field error and F-J stability

    CERN Document Server

    Collings, E W; Lee, E

    2001-01-01

    In hadron accelerators, between low energy particle injection and beam accumulation, the guiding dipoles are ramped at some rate dB/dt. Both at injection and during ramping the static and dynamic magnetizations of the magnet windings introduce multipolar distortions into the beam-line field. Dynamic magnetization, controllable by cable design, is estimated and used to provide a criterion against which to evaluate the allowable magnitude of static (persistent-current) magnetization, M, from a field-quality standpoint. The it is of NbTi and advanced Nb/sub 3/Sn conductors are compared and with regard to the latter the question of flux-jump stability is explored. A magnetization criterion for such stability is presented and compared to experiment. It is noted that since Delta M is proportional to critical current density, J/sub c/, and the strand's effective filament diameter, d/sub eff/, the latter has frequently been specified as a critical parameter, although it will need to be re-specified with every increas...

  7. Performance of the cold powered diodes and diode leads in the main magnets of the LHC

    CERN Document Server

    Willering, G P; Bajko, M; Bednarek, M; Bottura, L; Charifoulline, Z; Dahlerup-Petersen, K; Dib, G; D'Angelo, G; Gharib, A; Grand-Clement, L; Izquierdo Bermudez, S; Prin, H; Roger, V; Rowan, S; Savary, F; Tock, J-Ph; Verweij, A

    2015-01-01

    During quench tests in 2011 variations in resistance of an order of magnitude were found in the diode by-pass circuit of the main LHC magnets. An investigation campaign was started to understand the source, the occurrence and the impact of the high resistances. Many tests were performed offline in the SM18 test facility with a focus on the contact resistance of the diode to heat sink contact and the diode wafer temperature. In 2014 the performance of the diodes and diode leads of the main dipole bypass systems in the LHC was assessed during a high current qualification test. In the test a current cycle similar to a magnet circuit discharge from 11 kA with a time constant of 100 s was performed. Resistances of up to 600 μΩ have been found in the diode leads at intermediate current, but in general the high resistances decrease at higher current levels and no sign of overheating of diodes has been seen and the bypass circuit passed the test. In this report the performance of the diodes and in particular the co...

  8. Neutron electric dipole moment and possibilities of increasing accuracy of experiments

    Energy Technology Data Exchange (ETDEWEB)

    Serebrov, A. P., E-mail: serebrov@pnpi.spb.ru; Kolomenskiy, E. A.; Pirozhkov, A. N.; Krasnoshchekova, I. A.; Vasiliev, A. V.; Polyushkin, A. O.; Lasakov, M. S.; Murashkin, A. N.; Solovey, V. A.; Fomin, A. K.; Shoka, I. V.; Zherebtsov, O. M. [National Research Centre “Kurchatov Institute”, Petersburg Nuclear Physics Institute (Russian Federation); Aleksandrov, E. B.; Dmitriev, S. P.; Dovator, N. A. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Geltenbort, P.; Ivanov, S. N.; Zimmer, O. [Institut Max von Laue–Paul Langevin (France)

    2016-01-15

    The paper reports the results of an experiment on searching for the neutron electric dipole moment (EDM), performed on the ILL reactor (Grenoble, France). The double-chamber magnetic resonance spectrometer (Petersburg Nuclear Physics Institute (PNPI)) with prolonged holding of ultra cold neutrons has been used. Sources of possible systematic errors are analyzed, and their influence on the measurement results is estimated. The ways and prospects of increasing accuracy of the experiment are discussed.

  9. Neutron electric dipole moment and possibilities of increasing accuracy of experiments

    Science.gov (United States)

    Serebrov, A. P.; Kolomenskiy, E. A.; Pirozhkov, A. N.; Krasnoshchekova, I. A.; Vasiliev, A. V.; Polyushkin, A. O.; Lasakov, M. S.; Murashkin, A. N.; Solovey, V. A.; Fomin, A. K.; Shoka, I. V.; Zherebtsov, O. M.; Aleksandrov, E. B.; Dmitriev, S. P.; Dovator, N. A.; Geltenbort, P.; Ivanov, S. N.; Zimmer, O.

    2016-01-01

    The paper reports the results of an experiment on searching for the neutron electric dipole moment (EDM), performed on the ILL reactor (Grenoble, France). The double-chamber magnetic resonance spectrometer (Petersburg Nuclear Physics Institute (PNPI)) with prolonged holding of ultra cold neutrons has been used. Sources of possible systematic errors are analyzed, and their influence on the measurement results is estimated. The ways and prospects of increasing accuracy of the experiment are discussed.

  10. Magnetic rotation phenomenon in the dipole (ΔI = 1) bands of transitional strontium (Sr) isotopes near N = 50 shell closure

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Naveen; Kumar, S.; Mandal, S.K. [University of Delhi, Department of Physics and Astrophysics, Delhi (India); Saha, S.; Sethi, J.; Palit, R. [Tata Institute of Fundamental Research, Department of Nuclear and Atomic Physics, Mumbai (India)

    2017-02-15

    The lifetime measurements were done for the transitions of the dipole (ΔI = 1) bands in {sup 85,86}Sr nuclei using the Doppler Shift Attenuation Method (DSAM). The high-spin states in these nuclei were populated in the {sup 76}Ge({sup 13}C, 4n){sup 85}Sr and {sup 76}Ge({sup 13}C, 3n){sup 86}Sr reactions. The B(M1) transition rates have been obtained for the states of two positive-parity dipole (Δ I = 1) bands in the {sup 85}Sr nucleus and one positive-parity dipole (ΔI = 1) band in the {sup 86} Sr nucleus. The present results on the transition rates are important to know whether these dipole (ΔI = 1) bands have the signatures of Magnetic Rotation (MR). In order to investigate their magnetic character, the experimental results have been compared with the calculations within the framework of hybrid Tilted-Axis-Cranking (TAC) model. On the basis of the TAC calculations, band 2 of the {sup 85}Sr nucleus is assigned the π(g{sub 9/2}){sup 2} x ν(g{sub 9/2}){sup -1} configuration and shows the MR character, while for band 3, the π[(g{sub 9/2}){sup 2}(f{sub 5/2}){sup 2}] x ν(g{sub 9/2}){sup -1} configuration is suggested. In the case of {sup 86}Sr nucleus, band 3 has the π(g{sub 9/2}){sup 2} x ν(g{sub 9/2}){sup -2} configuration below the spin I{sup π} = 16{sup +} and above this spin the π[(g{sub 9/2}){sup 2}(f{sub 5/2}){sup 1}(p{sub 1/2}/p{sub 3/2}){sup 1}] x ν(g{sub 9/2}){sup -2} configuration plays an important role. The experimental B(M1) transition rates show a decreasing trend with the increase in spin and are comparable with the TAC calculations before the I{sup π} = 16{sup +}. (orig.)

  11. Testing of a Single 11 T $Nb_3Sn$ Dipole Coil Using a Dipole Mirror Structure

    Energy Technology Data Exchange (ETDEWEB)

    Zlobin, Alexander [Fermilab; Andreev, Nicolai [Fermilab; Barzi, Emanuela [Fermilab; Chlachidze, Guram [Fermilab; Kashikhin, Vadim [Fermilab; Nobrega, Alfred [Fermilab; Novitski, Igor [Fermilab; Turrioni, Daniele [Fermilab; Karppinen, Mikko [CERN; Smekens, David [CERN

    2014-07-01

    FNAL and CERN are developing an 11 T Nb3Sn dipole suitable for installation in the LHC. To optimize coil design parameters and fabrication process and study coil performance, a series of 1 m long dipole coils is being fabricated. One of the short coils has been tested using a dipole mirror structure. This paper describes the dipole mirror magnetic and mechanical designs, and reports coil parameters and test results.

  12. LHC Dipoles Accelerate

    CERN Multimedia

    2001-01-01

    Andrezej Siemko (left), Peter Sievers (centre), and Lucio Rossi (right), have the exciting challenge of preparing and testing 2000 magnets for the LHC. The LHC is going to require a lot of powerful magnets by the time it begins operation in 2006. More specifically, it is going to need 130 special magnets, 400 quadrupoles, and a whopping 1250 dipoles! Preparing and testing these magnets for the conditions they will encounter in the LHC is not an easy task. But evaluation of the most recently received magnet, from the German company Noell, is showing that while the monumental task of receiving and testing nearly 2000 magnets is going to be exhausting, the goals are definitely attainable. At the moment and over the next year, pre-series magnets (the magnets that CERN uses to fine tune performance) are arriving slowly (90 in total will arrive), but by 2003 the rate of series magnet arrival will accelerate to 9 per week, that's over 450 in a single year! And working with these magnets when they arrive is tough. ...

  13. Magnetohydrodynamic Simulations of Disk Galaxy Formation: the Magnetization of The Cold and Warm Medium

    CERN Document Server

    Wang, Peng

    2007-01-01

    Using magnetohydrodynamic (MHD) adaptive mesh refinement simulations, we study the formation and early evolution of disk galaxies with a magnetized interstellar medium. For a $10^{10}$ \\msun halo with initial NFW dark matter and gas profiles, we impose a uniform $10^{-9}$ G magnetic field and follow its collapse, disk formation and evolution up to 1 Gyr. Comparing to a purely hydrodynamic simulation with the same initial condition, we find that a protogalactic field of this strength does not significantly influence the global disk properties. At the same time, the initial magnetic fields are quickly amplified by the differentially rotating turbulent disk. After the initial rapid amplification lasting $\\sim500$ Myr, subsequent field amplification appears self-regulated. As a result, highly magnetized material begin to form above and below the disk. Interestingly, the field strengths in the self-regulated regime agrees well with the observed fields in the Milky Way galaxy both in the warm and the cold HI phase ...

  14. Diffusive Transport Particle Simulations of Cold and Hot Ions Under Northward Interplanetary Magnetic Field

    Science.gov (United States)

    Mata, W.; Wang, C.; Lemon, C. L.; Lyons, L. R.

    2013-12-01

    The main difference seen in the plasma sheet between northward interplanetary magnetic field (NIMF) and southward interplanetary magnetic field (SIMF) intervals is that the plasma sheet is colder and denser during NIMF [e.g., Terasawa et al., 1997]. The basic processes responsible for these changes in the plasma sheet during NIMF and SIMF are not fully understood. The plasma sheet densities increase gradually following a northward turning of the IMF [Wing et al., 2005], and the density change is associated with a < ~1 keV cold population near the flanks. Observations also show a large variation in density across the tail with higher densities near the flanks than at midnight [e.g., Wing and Newell.,2002; Wang et al., 2006], which suggests that there are transport processes that allow the cold particles access to the midnight sector from the flanks. It has been proposed [e.g., Terasawa et al., 1997; Antonova, 2006] that diffusion may transport cold particles from the flanks deep into the plasma sheet. Diffusive particle transport results from fluctuations in the plasma sheet flow in the presence of a spatial gradient in the particle number. In this study we add electric and magnetic field perturbations to the background Tsyganenko 2001 (T01) magnetic field and Weimer 2000 electric potential with the superposition of different waves to determine whether diffusive transport can account for the gradual cooling and densification of the plasma sheet during NIMF. We follow the guiding center drift and full particle drift, where appropriate, of over 20,000 protons with arbitrary pitch angles and energies from 32 eV-30 keV in the simulation region from X = -10 to -50 and |Y| < 20 RE .We then obtain particle distributions by mapping the phase space densities to realistic source distributions based on THEMIS and Geotail observations and compute the resulting plasma moments. We investigate if diffusion can transport colder ions more efficiently than the hotter ions from the

  15. Nuclear magnetic relaxation induced by exchange-mediated orientational randomization: Longitudinal relaxation dispersion for a dipole-coupled spin-1/2 pair

    Science.gov (United States)

    Chang, Zhiwei; Halle, Bertil

    2013-10-01

    In complex biological or colloidal samples, magnetic relaxation dispersion (MRD) experiments using the field-cycling technique can characterize molecular motions on time scales ranging from nanoseconds to microseconds, provided that a rigorous theory of nuclear spin relaxation is available. In gels, cross-linked proteins, and biological tissues, where an immobilized macromolecular component coexists with a mobile solvent phase, nuclear spins residing in solvent (or cosolvent) species relax predominantly via exchange-mediated orientational randomization (EMOR) of anisotropic nuclear (electric quadrupole or magnetic dipole) couplings. The physical or chemical exchange processes that dominate the MRD typically occur on a time scale of microseconds or longer, where the conventional perturbation theory of spin relaxation breaks down. There is thus a need for a more general relaxation theory. Such a theory, based on the stochastic Liouville equation (SLE) for the EMOR mechanism, is available for a single quadrupolar spin I = 1. Here, we present the corresponding theory for a dipole-coupled spin-1/2 pair. To our knowledge, this is the first treatment of dipolar MRD outside the motional-narrowing regime. Based on an analytical solution of the spatial part of the SLE, we show how the integral longitudinal relaxation rate can be computed efficiently. Both like and unlike spins, with selective or non-selective excitation, are treated. For the experimentally important dilute regime, where only a small fraction of the spin pairs are immobilized, we obtain simple analytical expressions for the auto-relaxation and cross-relaxation rates which generalize the well-known Solomon equations. These generalized results will be useful in biophysical studies, e.g., of intermittent protein dynamics. In addition, they represent a first step towards a rigorous theory of water 1H relaxation in biological tissues, which is a prerequisite for unravelling the molecular basis of soft

  16. Construction of a stable and homogeneous magnetic field at 10 milligauss for neutron electric dipole moment measurements: preparatory phase

    Energy Technology Data Exchange (ETDEWEB)

    Gravador, E.; Yoshiki, Hajime; Feizeng, H. [Ibaraki Univ., Mito (Japan)

    1996-08-01

    A superthermal UCN edm measuring machine is currently under construction at KEK. It utilizes a magnetically shielded superconducting solenoid at liquid helium temperature to generate a stable and homogeneous magnetic field at 10 milligauss. The design of the magnetic shield and solenoid and preliminary evaluation of shielding effectiveness is presented. (author)

  17. Axion Induced Oscillating Electric Dipole Moments

    CERN Document Server

    Hill, Christopher T

    2015-01-01

    The axion electromagnetic anomaly induces an oscillating electric dipole for any static magnetic dipole. Static electric dipoles do not produce oscillating magnetic moments. This is a low energy theorem which is a consequence of the space-time dependent cosmic background field of the axion. The electron will acquire an oscillating electric dipole of frequency $m_a$ and strength $\\sim 10^{-32}$ e-cm, two orders of magnitude above the nucleon, and within four orders of magnitude of the present standard model DC limit. This may suggest sensitive new experimental venues for the axion dark matter search.

  18. RHIC spin flipper AC dipole controller

    Energy Technology Data Exchange (ETDEWEB)

    Oddo, P.; Bai, M.; Dawson, C.; Gassner, D.; Harvey, M.; Hayes, T.; Mernick, K.; Minty, M.; Roser, T.; Severino, F.; Smith, K.

    2011-03-28

    The RHIC Spin Flipper's five high-Q AC dipoles which are driven by a swept frequency waveform require precise control of phase and amplitude during the sweep. This control is achieved using FPGA based feedback controllers. Multiple feedback loops are used to and dynamically tune the magnets. The current implementation and results will be presented. Work on a new spin flipper for RHIC (Relativistic Heavy Ion Collider) incorporating multiple dynamically tuned high-Q AC-dipoles has been developed for RHIC spin-physics experiments. A spin flipper is needed to cancel systematic errors by reversing the spin direction of the two colliding beams multiple times during a store. The spin flipper system consists of four DC-dipole magnets (spin rotators) and five AC-dipole magnets. Multiple AC-dipoles are needed to localize the driven coherent betatron oscillation inside the spin flipper. Operationally the AC-dipoles form two swept frequency bumps that minimize the effect of the AC-dipole dipoles outside of the spin flipper. Both AC bumps operate at the same frequency, but are phase shifted from each other. The AC-dipoles therefore require precise control over amplitude and phase making the implementation of the AC-dipole controller the central challenge.

  19. In vivo assessment of cold adaptation in insect larvae by magnetic resonance imaging and magnetic resonance spectroscopy.

    Directory of Open Access Journals (Sweden)

    Daniel Mietchen

    Full Text Available BACKGROUND: Temperatures below the freezing point of water and the ensuing ice crystal formation pose serious challenges to cell structure and function. Consequently, species living in seasonally cold environments have evolved a multitude of strategies to reorganize their cellular architecture and metabolism, and the underlying mechanisms are crucial to our understanding of life. In multicellular organisms, and poikilotherm animals in particular, our knowledge about these processes is almost exclusively due to invasive studies, thereby limiting the range of conclusions that can be drawn about intact living systems. METHODOLOGY: Given that non-destructive techniques like (1H Magnetic Resonance (MR imaging and spectroscopy have proven useful for in vivo investigations of a wide range of biological systems, we aimed at evaluating their potential to observe cold adaptations in living insect larvae. Specifically, we chose two cold-hardy insect species that frequently serve as cryobiological model systems--the freeze-avoiding gall moth Epiblema scudderiana and the freeze-tolerant gall fly Eurosta solidaginis. RESULTS: In vivo MR images were acquired from autumn-collected larvae at temperatures between 0 degrees C and about -70 degrees C and at spatial resolutions down to 27 microm. These images revealed three-dimensional (3D larval anatomy at a level of detail currently not in reach of other in vivo techniques. Furthermore, they allowed visualization of the 3D distribution of the remaining liquid water and of the endogenous cryoprotectants at subzero temperatures, and temperature-weighted images of these distributions could be derived. Finally, individual fat body cells and their nuclei could be identified in intact frozen Eurosta larvae. CONCLUSIONS: These findings suggest that high resolution MR techniques provide for interesting methodological options in comparative cryobiological investigations, especially in vivo.

  20. Passive temperature compensation in hybrid magnets with application to the Fermilab stacker and recycler ring dipole design

    Energy Technology Data Exchange (ETDEWEB)

    Schlueter, R.D.; Marks, S.; Loper, C.; Halbach, K.

    1995-06-01

    Design theory of hybrid (permanent magnet plus iron) accelerator magnets with application to the proposed permanent magnet recycler and stacker rings at the Fermi National Laboratory is presented. Field stability in such devices requires that changes in the strength of the permanent magnet material with temperature be compensated. Field tuning techniques, including those employing variable capacitance between energized pole and magnet yoke and those employing variable energization of magnet pole pieces, are described. Mechanical configurations capable of achieving temperature compensation passively, including use of expanding liquids/gases and bimetallic springs are outlined. Active configurations, relying on a actuator, in addition to temperature compensation, have the additional benefit of enabling magnet tuning about a nominal operating field level.

  1. A measurement of the magnetic dipole moment of the. delta. /sup + +/(1232) from the bremsstrahlung process. pi. p. -->. pi. p. gamma

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, C.A.

    1987-06-01

    We have measured the cross section from the bremsstrahlung process ..pi../sup +/p ..-->.. ..pi../sup +/p..gamma.. for incident pions of energy 299 MeV. We detected the out going pion in the angular range from 55 to 95/sup 0/ in the lab, and photons were detected near 240/sup 0/ in the lab. We compare this measured cross-section to the MIT theory in order to extract a measurement of the magnetic dipole moment of the ..delta../sup + +/(1232), ..mu../sub ..delta../. In order to compare our results with the MIT theory, we have folded the MIT theory into the acceptance of our apparatus. We find that for pion angles between 55 and 75/sup 0/ the theory gives us a dipole moment of: 2.3..mu../sub p/ < ..mu../sub ..delta../ < 3.3..mu../sup p/ where the quoted error arises from an experimental uncertainty of +-0.25..mu../sub p/ and from theoretical uncertainties of +-0.25 ..mu../sub p/. However, for pion angles between 75 and 95/sup 0/ we find that the MIT theory predicts a cross-section which is larger than our measured cross-section, and makes it difficult to extract a value of ..mu../sub ..delta../. This over prediction is not understood, but consistent with a similar effect when the MIT theory is fit to previous data. 78 figs., 29 tabs.

  2. Nuclear Magnetic Resonance Structure of a Major Lens Protein, Human γC-Crystallin: Role of the Dipole Moment in Protein Solubility.

    Science.gov (United States)

    Dixit, Karuna; Pande, Ajay; Pande, Jayanti; Sarma, Siddhartha P

    2016-06-07

    A hallmark of the crystallin proteins is their exceptionally high solubility, which is vital for maintaining the high refractive index of the eye lens. Human γC-crystallin is a major γ-crystallin whose mutant forms are associated with congenital cataracts but whose three-dimensional structure is not known. An earlier study of a homology model concluded that human γC-crystallin has low intrinsic solubility, mainly because of the atypical magnitude and fluctuations of its dipole moment. On the contrary, the high-resolution tertiary structure of human γC-crystallin determined here shows unequivocally that it is a highly soluble, monomeric molecule in solution. Notable differences between the orientations and interactions of several side chains are observed upon comparison to those in the model. No evidence of the pivotal role ascribed to the effect of dipole moment on protein solubility was found. The nuclear magnetic resonance structure should facilitate a comprehensive understanding of the deleterious effects of cataract-associated mutations in human γC-crystallin.

  3. Design and Manufacture of a Large-Bore 10 T Superconducting Dipole for the CERN Cable Test Facility

    CERN Document Server

    Leroy, D; Verweij, A P; Boschmann, H; Dubbeldam, R L; González-Pelayo, J

    2000-01-01

    A large-bore 10 T superconducting dipole magnet was designed and fabricated in close cooperation between CERN and HMA Power Systems. The dipole has a length of about 1.7 m and an aperture of 88 mm and is composed of two two-layer poles wound with NbTi cables cooled to 1.9 K to reach magnetic inductions close to 10 T. This dipole will be installed at the CERN cable test facility and used as a background field magnet to test LHC superconducting cables. In its large aperture up to four cable samples can be tested at the same time. The mechanical design of the magnet is such that coil prestress variations between warm and cold conditions are kept within 20 MPa. A short model was also built and cooled down in order to check and confirm with test results the mechanical behavior of the dipole. Magnetic measurements, at room temperature, were performed upon its arrival at CERN prior to installation in the test facility. The dipole was recently cooled down and tested. This paper will discuss the design, the main manu...

  4. Dipoles, unintentional antennas and EMC

    Directory of Open Access Journals (Sweden)

    Berend Danker

    2008-01-01

    Full Text Available Radiated emissions from equipment commonly originate from electronic circuits that act as electric dipoles created by the signal voltage between the signal conductors or as magnetic dipoles formed by the signal current flowing in a loop. Direct emission is mostly small, but circuits often couple to long conductors or large wiring loops which act as antennas and are efficient radiators. A comparable situation exists when short dipole antennas or small wiring loops receive ambient noise (susceptibility. Usually the amplitude of noise sources or the susceptibility of circuits is an invariable. The dipole strength increases with the distance between the conductors and the area. Shielding and proper grounding decreases the interaction via unintentional antennas. Short-circuiting and the insertion of lossy ferrite cores reduce the efficiency of unintentional antennas.

  5. An Upper Bound on the Strongly Forbidden $6S_{1/2} \\leftrightarrow 5D_{3/2}$ Magnetic Dipole Transition Moment in {Ba}$^{+}$

    CERN Document Server

    Williams, Spencer R; Hoffman, Matthew R; Blinov, Boris B; Fortson, E N

    2016-01-01

    We report the results from our first-generation experiment to measure the magnetic-dipole transition moment (M1) between the $6S_{1/2}$ and $5D_{3/2}$ manifolds in Ba$^{+}$. Knowledge of M1 is crucial for the proposed parity-nonconservation experiment in the ion \\cite{Fortson93}, where M1 will be a leading source of systematic error. To date, no measurement of M1 has been made in Ba$^{+}$, and moreover, the sensitivity of the moment to electron-electron correlations has confounded accurate theoretical predictions. A precise measurement may help to resolve the theoretical discrepancies while providing essential information for planning a future PNC measurement in Ba$^{+}$. We demonstrate our technique for measuring M1 - including a method for calibrating for stress-induced birefringence introduced by the scientific apparatus - and place an upper bound of $\\mathrm{M1} < 93 \\pm 39 \\times 10^{-5} \\mu_{B}$.

  6. Effect of severe plastic deformation on the specific heat and magnetic properties of cold rolled Gd sheets

    Science.gov (United States)

    Taskaev, S.; Skokov, K.; Khovaylo, V.; Buchelnikov, V.; Pellenen, A.; Karpenkov, D.; Ulyanov, M.; Bataev, D.; Usenko, A.; Lyange, M.; Gutfleisch, O.

    2015-03-01

    We report on specific heat and magnetic properties of thin Gd sheets obtained by means of a cold rolling technique. At temperatures well below Curie temperature TC, the cold rolling has a minor impact on the specific heat Cp. However, a well defined λ-type anomaly of Cp seen in the vicinity of TC in a polycrystalline Gd sample is markedly suppressed in the severely deformed samples. Depression of the λ peak is due to a large decrease of magnetization that presumably originates in a local magnetic anisotropy induced by the severe plastic deformation. Results of calculation of magnetocaloric effect from the Cp and magnetization data indicate that the magnetocaloric effect gradually decreases as the degree of plastic deformation increases. This trend is further confirmed by the direct measurements of the adiabatic temperature change ΔTad.

  7. Cold collisions of N atoms and NH molecules in magnetic fields

    CERN Document Server

    Zuchowski, Piotr S \\

    2010-01-01

    We calculate the interaction potential between N atoms and NH molecules and use it to investigate cold and ultracold collisions important for sympathetic cooling. The ratio of elastic to inelastic cross sections is large over a wide range of collision energy and magnetic field for most isotopic combinations, so that sympathetic cooling of NH molecules by N atoms is a good prospect. However, there are important effects due to a p-wave shape resonance that may inhibit cooling in some cases. We show that scaling the reduced mass used in the collision is approximately equivalent to scaling the interaction potential. We then explore the dependence of the scattering properties on the reduced mass and explain the resonant effects observed using angular-momentum-insensitive quantum defect theory

  8. Multiple scattering of light in cold atomic clouds with a magnetic field

    CERN Document Server

    Sigwarth, Olivier; Delande, Dominique; Miniatura, Christian

    2013-01-01

    Starting from a microscopic theory for atomic scatterers, we describe the scattering of light by a single atom and study the coherent propagation of light in a cold atomic cloud in the presence of a magnetic field B in the mesoscopic regime. Non-pertubative expressions in B are given for the magneto-optical effects and optical anisotropy. We then consider the multiple scattering regime and address the fate of the coherent backscattering (CBS) effect. We show that, for atoms with nonzero spin in their ground state, the CBS interference contrast can be increased compared to its value when B=0, a result at variance with classical samples. We validate our theoretical results by a quantitative comparison with experimental data.

  9. Energy and charge dependence of the rate of electron-ion recombination in cold magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Gao, H.; Schuch, R.; Zong, W.; Justiniano, E.; DeWitt, D.R.; Lebius, H.; Spies, W. [Stockholm Univ., Atomic Physics Dept., Stockholm (Sweden)

    1997-07-28

    We have measured electron-ion recombination rates for bare ions of D{sup +}, He{sup 2+}, N{sup 7+}, Ne{sup 10+} and Si{sup 14+} in a storage ring. For the multi-charged ions an unexpected energy dependence was found, showing a strong increase of the measured rates over the calculated radiative recombination rate for electron beam detuning energies below the electron beam transverse temperature. The measured enhanced rates increase approximately as Z{sup 2.8} with the charge state Z. A comparison of these rates with theoretical predictions for collisional-radiative recombination in the cold magnetized electron plasma, in particular three-body recombination including radiative de-excitation of electrons in Rydberg levels, is made. (author).

  10. Determining Ms temperature on a AISI D2 cold work tool steel using magnetic Barkhausen noise

    Energy Technology Data Exchange (ETDEWEB)

    Huallpa, Edgar Apaza, E-mail: gared1@gmail.com [Escola Politécnica da Universidade de São Paulo, Av. Prof. Mello Moraes 2463, 05508-030 SP (Brazil); Sánchez, J. Capó, E-mail: jcapo@usp.br [Departamento de Física, Facultad de Ciencias Naturales, Universidad de Oriente, Av. Patricio Lumumba s/n 90500, Santiago de Cuba (Cuba); Padovese, L.R., E-mail: lrpadove@usp.br [Escola Politécnica da Universidade de São Paulo, Av. Prof. Mello Moraes 2463, 05508-030 SP (Brazil); Goldenstein, Hélio, E-mail: hgoldens@usp.br [Escola Politécnica da Universidade de São Paulo, Av. Prof. Mello Moraes 2463, 05508-030 SP (Brazil)

    2013-11-15

    Highlights: ► MBN was used to follow the martensite transformation in a tool steel. ► The results were compared with resistivity experiments. ► The Ms was estimated with Andrews equation coupled to ThermoCalc calculations. The experimental results showed good agreement. -- Abstract: The use of Magnetic Barkhausen Noise (MBN) as a experimental method for measuring the martensite start (Ms) temperature was explored, using as model system a cold-work tool steel (AISI D2) austenitized at a very high temperature (1473 K), so as to transform in sub-zero temperatures. The progress of the transformation was also followed with electrical resistance measurements, optical microscopy and scanning electron microscopy. Both MBN and resistivity measurements showed a change near 230 K during cooling, corresponding to the Ms temperature, as compared with 245 K, estimated with Andrews empirical equation applied to the austenite composition calculated using ThermoCalc.

  11. Nonlinear dynamics of cold magnetized non-relativistic plasma in the presence of electron-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, Biswajit, E-mail: biswajit-sahu@yahoo.co.in [Department of Mathematics, West Bengal State University, Barasat, Kolkata 700126 (India); Sinha, Anjana, E-mail: sinha.anjana@gmail.com [Department of Instrumentation Science, Jadavpur University, Kolkata 700 032 (India); Roychoudhury, Rajkumar, E-mail: rroychoudhury123@gmail.com [Department of Mathematics, Visva-Bharati, Santiniketan - 731 204, India and Advanced Centre for Nonlinear and Complex Phenomena, 1175 Survey Park, Kolkata 700 075 (India)

    2015-09-15

    A numerical study is presented of the nonlinear dynamics of a magnetized, cold, non-relativistic plasma, in the presence of electron-ion collisions. The ions are considered to be immobile while the electrons move with non-relativistic velocities. The primary interest is to study the effects of the collision parameter, external magnetic field strength, and the initial electromagnetic polarization on the evolution of the plasma system.

  12. Visualizing dipole radiation

    Science.gov (United States)

    Girwidz, Raimund V.

    2016-11-01

    The Hertzian dipole is fundamental to the understanding of dipole radiation. It provides basic insights into the genesis of electromagnetic waves and lays the groundwork for an understanding of half-wave antennae and other types. Equations for the electric and magnetic fields of such a dipole can be derived mathematically. However these are very abstract descriptions. Interpreting these equations and understanding travelling electromagnetic waves are highly limited in that sense. Visualizations can be a valuable supplement that vividly present properties of electromagnetic fields and their propagation. The computer simulation presented below provides additional instructive illustrations for university lectures on electrodynamics, broadening the experience well beyond what is possible with abstract equations. This paper refers to a multimedia program for PCs, tablets and smartphones, and introduces and discusses several animated illustrations. Special features of multiple representations and combined illustrations will be used to provide insight into spatial and temporal characteristics of field distributions—which also draw attention to the flow of energy. These visualizations offer additional information, including the relationships between different representations that promote deeper understanding. Finally, some aspects are also illustrated that often remain unclear in lectures.

  13. Superconducting dipole electromagnet

    Science.gov (United States)

    Purcell, John R.

    1977-07-26

    A dipole electromagnet of especial use for bending beams in particle accelerators is wound to have high uniformity of magnetic field across a cross section and to decrease evenly to zero as the ends of the electromagnet are approached by disposing the superconducting filaments of the coil in the crescent-shaped nonoverlapping portions of two intersecting circles. Uniform decrease at the ends is achieved by causing the circles to overlap increasingly in the direction of the ends of the coil until the overlap is complete and the coil is terminated.

  14. Oblique propagation of solitary electrostatic waves in magnetized plasmas with cold ions and nonthermal electrons

    Science.gov (United States)

    Verheest, Frank; Hellberg, Manfred A.

    2017-02-01

    Oblique propagation of large amplitude electrostatic waves and solitary structures is investigated in magnetized plasmas, comprising cold fluid ions and Cairns nonthermally distributed electrons, by using a Sagdeev pseudopotential formalism. To perform the analysis, quasineutrality is assumed, so that in normalized variables the electrostatic potential and the occurrence of solitary structures are governed by three parameters: the Mach number M, the typical Cairns parameter β, and the angle ϑ between the directions of propagation and the static magnetic field. Below a critical β, only positive compressive solitons are possible, and their amplitudes increase with increasing β, M, and ϑ. Above the critical β, there is coexistence between negative rarefactive and positive compressive solitons, and the range of negative solitons, at increasing M, ends upon encountering a double layer or a singularity. The double layer amplitudes (in absolute value) increase with β but are independent of ϑ. Roots of the Sagdeev pseudopotential beyond the double layer are not accessible from the undisturbed conditions, because of an intervening singularity where the pseudopotential becomes infinite. Recent claims of finding supersolitons beyond a double layer appear to be based on a misinterpretation of the nature of the singularity.

  15. Integral Measurement of Dipole Prototype of CSR

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The dipole prototype is C type used as bending magnet of the injection beam line in CSR, and acts as a model of the dipoles in the CSR main ring simultaneously. The designed relative uniformity of good field is 0.001 in 100 mm width. The results of the local distribution and transfunction at transverse profile measured

  16. Vibrational state-selective autodetachment photoelectron spectroscopy from dipole-bound states of cold 2-hydroxyphenoxide: o − HO(C{sub 6}H{sub 4})O{sup −}

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Dao-Ling; Wang, Lai-Sheng, E-mail: Lai-Sheng-Wang@brown.edu [Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States); Liu, Hong-Tao [Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States); Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Ning, Chuan-Gang [Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China)

    2015-03-28

    We report a photodetachment and high-resolution photoelectron imaging study of cold 2-hydroxyphenoxide anion, o − HO(C{sub 6}H{sub 4})O{sup −}, cooled in a cryogenic ion trap. Photodetachment spectroscopy revealed a dipole-bound state (DBS) of the anion, 25 ± 5 cm{sup −1}, below the detachment threshold of 18784 ± 5 cm{sup −1} (2.3289 ± 0.0006 eV ), i.e., the electron affinity of the 2-hydroxyphenoxy radical o − HO(C{sub 6}H{sub 4})O{sup ⋅}. Twenty-two vibrational levels of the DBS are observed as resonances in the photodetachment spectrum. By tuning the detachment laser to these DBS vibrational levels, we obtain 22 high-resolution resonant photoelectron spectra, which are highly non-Franck-Condon due to mode-selective autodetachment and the Δv = − 1 propensity rule. Numerous Franck-Condon inactive vibrational modes are observed in the resonant photoelectron spectra, significantly expanding the vibrational information that is available in traditional high-resolution photoelectron spectroscopy. A total of 15 fundamental vibrational frequencies are obtained for the o − HO(C{sub 6}H{sub 4})O{sup ⋅}  radical from both the photodetachment spectrum and the resonant photoelectron spectra, including six symmetry-forbidden out-of-plane modes as a result of resonant enhancement.

  17. SMC X-3: the closest ultraluminous X-ray source powered by a neutron star with non-dipole magnetic field

    Science.gov (United States)

    Tsygankov, S. S.; Doroshenko, V.; Lutovinov, A. A.; Mushtukov, A. A.; Poutanen, J.

    2017-09-01

    Aims: The magnetic field of accreting neutron stars determines their overall behavior including the maximum possible luminosity. Some models require an above-average magnetic field strength (≳1013 G) in order to explain super-Eddington mass accretion rate in the recently discovered class of pulsating ultraluminous X-ray sources (ULX). The peak luminosity of SMC X-3 during its major outburst in 2016-2017 reached 2.5 × 1039 erg s-1 comparable to that in ULXs thus making this source the nearest ULX-pulsar. Determination of the magnetic field of SMC X-3 is the main goal of this paper. Methods: SMC X-3 belongs to the class of transient X-ray pulsars with Be optical companions, and exhibited a giant outburst in July 2016-March 2017. The source has been observed over the entire outburst with the Swift/XRT and Fermi/GBM telescopes, as well as the NuSTAR observatory. Collected data allowed us to estimate the magnetic field strength of the neutron star in SMC X-3 using several independent methods. Results: Spin evolution of the source during and between the outbursts, and the luminosity of the transition to the so-called propeller regime in the range of (0.3-7) × 1035 erg s-1 imply a relatively weak dipole field of (1-5) × 1012 G. On the other hand, there is also evidence for a much stronger field in the immediate vicinity of the neutron star surface. In particular, transition from super- to sub-critical accretion regime associated with the cease of the accretion column and very high peak luminosity favor a field that is an order of magnitude stronger. This discrepancy makes SMC X-3 a good candidate for possessing significant non-dipolar components of the field, and an intermediate source between classical X-ray pulsars and accreting magnetars which may constitute an appreciable fraction of ULX population.

  18. Study of a 5T Research Dipole Insert-Magnet using an Anisotropic ReBCO Roebel Cable

    CERN Document Server

    Van Nugteren, J; De Rijk, G; Rossi, L; Ten Kate, H H J; Dhallé, M M J

    2015-01-01

    A design study is presented for the coil layout of the EuCARD-2 Fiver Tesla HTS Research (FeaTHeR) magnet. The angular dependence of the critical current in the used ReBCO Roebel cable is taken into account. This leads to a new coil layout named aligned block. This layout makes optimal use of the anisotropy of the ReBCO coated conductor, by aligning all tapes with the magnetic field lines. Both two dimensional cross sections and three dimensional coil layouts are presented. In the layouts the magnetic field angle is highest at the edges of the cable causing a large variation of the critical current over its width. Different approaches to the calculation of the critical current, with and without current sharing in and between the tapes, are presented. The values are compared to the values found using a non-linear network model of the cable, in which the electrical properties of the elements are calculated as a function of magnetic field and magnetic field angle. The model also includes electrical contact betwe...

  19. A Method for Measuring the $6S_{1/2} \\leftrightarrow 5D_{3/2}$ Magnetic Dipole Transition Moment in {Ba}$^{+}$

    CERN Document Server

    Williams, Spencer R; Hoffman, Matthew R; Blinov, Boris B; Fortson, E N

    2013-01-01

    We propose a method for measuring the magnetic dipole (M1) transition moment of the $6S_{1/2} \\big(\\mathrm{m}=-1/2\\big)\\leftrightarrow 5D_{3/2}\\big(\\mathrm{m}=-1/2\\big)$ transition in single trapped Ba$^{+}$ by exploiting different symmetries in the electric quadrupole (E2) and M1 couplings between the states. The technique is adapted from a previously proposed method for measuring atomic parity nonconservation in a single trapped ion [Norval Fortson, Phys. Rev. Lett. \\textbf{70}, 17 (1993)]. Knowledge of M1 is crucial for any parity nonconservation measurement in Ba$^{+}$, as laser coupling through M1 can mimic the parity-violating signal. The magnetic moment for the transition has been calculated by atomic theory and found to be dominated by electron-electron correlation effects [B.K. Sahoo et. al., Phys. Rev. A \\textbf{74}, 6 (2006)]. To date the value has not been verified experimentally. This proposed measurement is therefore an essential step toward a parity nonconservation experiment in the ion that wi...

  20. Technology of superconducting accelerator dipoles

    Energy Technology Data Exchange (ETDEWEB)

    Hassenzahl, W.V.; Meuser, R.B.; Taylor, C.

    1983-06-01

    We discuss accelerator dipoles and their characteristics. Other types of magnets, in particular bubble chamber magnets have been quite successful. Their performance is based on cryogenic stability which is addressed only briefly in this chapter. This type of stability is not available to the accelerator designer because of the large quantities of copper or other stabilizer that would reduce the current density in the windings to an unacceptably low value.

  1. Degenerate mixing of plasma waves on cold, magnetized single-species plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, M. W.; O' Neil, T. M.; Dubin, D. H. E.; Gould, R. W. [Physics Department, University of California at San Diego, La Jolla, California 92093 (United States)

    2011-10-15

    In the cold-fluid dispersion relation {omega}={omega}{sub p}/[1+(k{sub perpendicular}/k{sub z}){sup 2}]{sup 1/2} for Trivelpiece-Gould waves on an infinitely long magnetized plasma cylinder, the transverse and axial wavenumbers appear only in the combination k{sub perpendicular}/k{sub z}. As a result, for any frequency {omega}<{omega}{sub p}, there are infinitely many degenerate waves, all having the same value of k{sub perpendicular}/k{sub z}. On a cold finite-length plasma column, these degenerate waves reflect into one another at the ends; thus, each standing-wave normal mode of the bounded plasma is a mixture of many degenerate waves, not a single standing wave as is often assumed. A striking feature of the many-wave modes is that the short-wavelength waves often add constructively along resonance cones given by dz/dr={+-}({omega}{sub p}{sup 2}/{omega}{sup 2}-1){sup 1/2}. Also, the presence of short wavelengths in the admixture for a predominantly long-wavelength mode enhances the viscous damping beyond what the single-wave approximation would predict. Here, numerical solutions are obtained for modes of a cylindrical plasma column with rounded ends. Exploiting the fact that the modes of a spheroidal plasma are known analytically (the Dubin modes), a perturbation analysis is used to investigate the mixing of low-order, nearly degenerate Dubin modes caused by small deformations of a plasma spheroid.

  2. A fiber-optic strain measurement and quench localization system for use in superconducting accelerator dipole magnets

    NARCIS (Netherlands)

    Oort, van Johannes M.; Scanlan, Ronald M.; Kate, ten Herman H.J.

    1995-01-01

    A novel fiber-optic measurement system for superconducting accelerator magnets is described. The principal component is an extrinsic Fabry-Perot interferometer to determine localized strain and stress in coil windings. The system can be used either as a sensitive relative strain measurement system o

  3. Dipole nano-laser

    Energy Technology Data Exchange (ETDEWEB)

    Protsenko, I E; Uskov, A V; Krotova, K E [Lebedev Physical Institute, Leninsky prospect 53, Moscow (Russian Federation); O' Reilly, E P [Tyndall National Institute, ' Lee Maltings' , Prospect Row, Cork (Ireland)], E-mail: protsen@sci.lebedev.ru, E-mail: protsenk@gmail.com

    2008-03-15

    Theoretically predicted 'dipole lasing', i.e., spontaneous excitation of coherent metal nano-particle dipole oscillations through interaction with a quantum-dot two-level system subject to population inversion is demonstrated. Equations for dipole lasing are the same as equations for ordinary laser, where the dipole momentum of nano-particle stands for the electromagnetic field cavity mode. Dipole lasing frequency corresponds to the localized plasmon resonance of the nano-particle. Dipole momentum of nano-particle leads to coherent dipole radiation. Optical cavity is not necessary, the size of the dipole laser can be smaller than the optical wavelength, i.e. it is dipole nano-laser. Threshold conditions and optical bistability in dipole nano-lasers are considered.

  4. Magnetic and magneto elastic properties of cobalt ferrite ceramic compacted through cold isostatic pressing

    Energy Technology Data Exchange (ETDEWEB)

    Indla, Srinivas; Das, Dibakar, E-mail: ddse@uohyd.ernet.in [School of Engineering Sciences and Technology, University of Hyderabad, Hyderabad 500046 (India); Chelvane, Arout [Advanced Magnetic Group, Defense Metallurgical Research Laboratory, Kanchanbagh, Hyderabad 500058 (India)

    2016-05-06

    Nano crystalline CoFe{sub 2}O{sub 4} powder was prepared by combustion synthesis method. As synthesized powder was calcined at an appropriate condition to remove the impurities and to promote phase formation. Phase pure CoFe{sub 2}O{sub 4} powder was pressed into cylindrical rod at an applied pressure of 200 MPa using a cold isostatic pressing. Sintering of the green compact at 1350°c for 12 hrs resulted in sintered cylindrical rod with ~85% of the theoretical density. Single phase cubic spinel structure was observed in the powder x-ray diffraction pattern of the sintered pellet. Scanning electron micrographs (SEM) of the as sintered pellet revealed the microstructure to be composed of ferrite grains of average size ~4 µm. Saturation magnetization of 72 emu/g and coercivity of 355 Oe were observed for cobalt ferrite sample. The magnetostriction was measured on a circular disc (12 mm diameter and 12 mm length) with the strain gauge (350 Ω) mounted on the flat surface of the circular disc. Magnetostriciton of 180 ppm and strain derivative of 1 × 10{sup −9} m/A were observed for the sintered CoFe{sub 2}O{sub 4} sample.

  5. LHC Dipoles: The countdown has begun

    CERN Multimedia

    2002-01-01

    One of the LHC dipole magnets has just achieved a record magnetic field of 9 Tesla in one go without quenching. The challenge now is to increase the production rate to 35 magnets a month by 2004. As a new information panel in Building 30 shows, the countdown has begun.

  6. Soft magnetism in nitrided Fe93Ni4Cr3 and Fe94Ni4T2 cold-rolled alloys

    NARCIS (Netherlands)

    Craus, CB; Chezan, AR; Chechenin, NG; Boerma, DO; Niesen, L

    2003-01-01

    The magnetic properties in relation with the structure of nitrided cold-rolled Fe93Ni4Cr3 and Fe94Ni4Ti2 were studied. Various low-temperature nitriding treatments were applied in order to obtain soft magnetic materials. We show that the magnetic anisotropy depends sensitively on the nitrogen conten

  7. Effect of power parameter and induction coil on magnetic field in cold crucible during continuous melting and directional solidification

    Directory of Open Access Journals (Sweden)

    Chen Ruirun

    2012-02-01

    Full Text Available Bottomless electromagnetic cold crucible is a new apparatus for continuous melting and directional solidification; however, improving its power efficiency and optimizing the configuration are important for experiment and production. In this study, a 3-D finite element (FE method based on experimental verification was applied to calculate the magnetic flux density (Bz. The effects of the power parameters and the induction coil on the magnetic field distribution in the cold crucible were investigated. The results show that higher current intensity and lower frequency are beneficial to the increase of Bz at both the segment midpoint and the slit location. The induction coil with racetrack section can induce greater Bz, and a larger gap between the induction coil and the shield ring increases Bz. The mechanism for this effect is also discussed.

  8. Thermal Analysis of the Fair SIS300 Model Dipole

    Science.gov (United States)

    Sorbi, M.; Alessandria, F.; Bellomo, G.; Fabbricatore, P.; Farinon, S.; Gambardella, U.; Musenich, R.; Volpini, G.

    2010-04-01

    Design activities, conductor R&D and model coil construction are under way for the development of a curved superconducting dipole for the fast cycled SIS300 synchrotron at FAIR at GSI. The main target is the construction within 2009 of a half-length model magnet (cold mass fully integrated in a horizontal cryostat). This magnet is designed for a maximum central field of 4.5 T in a bore of 100 mm, with a ramp rate of 1 T/s. The magnetic length of the model is 3.9 m with a curvature radius of 66.67 m (27 mm of sagitta). This paper describes the thermal analysis of the magnet, based on the estimated values of the losses in the cold mass. The study has been performed with 2-D finite element codes, both in steady state and transient analysis. The study has been completed with measurements of overall thermal exchange coefficient between the kapton-insulated cables and the supercritical helium, in order to validate the adopted assumptions about the material thermal properties.

  9. Quantum Zeno suppression of dipole-dipole forces

    CERN Document Server

    Wüster, Sebastian

    2016-01-01

    We consider inter-atomic forces due to resonant dipole-dipole interactions within a dimer of highly excited Rydberg atoms, embedded in an ultra-cold gas. These forces rely on a coherent superposition of two-atom electronic states, which is destroyed by continuous monitoring of the dimer state through a detection scheme utilizing controllable interactions with the background gas atoms. We show that this intrinsic decoherence of the molecular energy surface can gradually deteriorate a repulsive dimer state, causing a mixing of attractive and repulsive character. For sufficiently strong decoherence, a Zeno-like effect causes a complete arrest of interatomic forces. We finally show how short decohering pulses can controllably redistribute population between the different molecular energy surfaces.

  10. Magnetic-dipole-to-electric-quadrupole cross-susceptibilities for relativistic hydrogenlike atoms in some low-lying discrete energy eigenstates

    CERN Document Server

    Stefańska, Patrycja

    2016-01-01

    In this paper we present tabulated data for magnetic-dipole-to-electric-quadrupole cross-susceptibilities ($\\chi_{\\textrm{M}1 \\to \\textrm{E}2}$) for Dirac one-electron atoms with a pointlike, spinless and motionless nucleus of charge $Ze$. Numerical values of this susceptibility for the hydrogen atom ($Z=1$) and for hydrogenic ions with $2 \\leqslant Z \\leqslant 137$ are computed from the general analytical formula, recently derived by us [P. Stefa{\\'n}ska, Phys. Rev. A 93 (2016) 022504], valid for an arbitrary discrete energy eigenstate. In this work we provide 30 tables with the values of $\\chi_{\\textrm{M}1 \\to \\textrm{E}2}$ for the ground state, and also for the first, the second and the third set of excited states (i.e.: 2s$_{1/2}$, 2p$_{1/2}$, 2p$_{3/2}$, 3s$_{1/2}$, 3p$_{1/2}$, 3p$_{3/2}$, 3d$_{3/2}$, 3d$_{5/2}$, 4s$_{1/2}$, 4p$_{1/2}$, 4p$_{3/2}$, 4d$_{3/2}$, 4d$_{5/2}$, 4f$_{5/2}$ and 4f$_{7/2}$) of the relativistic hydrogenlike atoms. The value of the inverse of the fine-structure constant used in the...

  11. A comparison of two magnetic ultra-cold neutron trapping concepts using a Halbach-octupole array

    CERN Document Server

    Leung, K; Martin, F; Rosenau, F; Simson, M; Zimmer, O

    2015-01-01

    This paper describes a new magnetic trap for ultra-cold neutrons (UCNs) made from a 1.2 m long Halbach-octupole array of permanent magnets with an inner bore radius of 47 mm combined with an assembly of superconducting end coils and bias field solenoid. The use of the trap in a vertical, magneto-gravitational and a horizontal setup are compared in terms of the effective volume and ability to control key systematic effects that need to be addressed in high precision neutron lifetime measurements.

  12. Optical force on toroidal nanostructures: toroidal dipole versus renormalized electric dipole

    CERN Document Server

    Zhang, Xu-Lin; Lin, Zhifang; Sun, Hong-Bo; Chan, C T

    2015-01-01

    We study the optical forces acting on toroidal nanostructures. A great enhancement of optical force is unambiguously identified as originating from the toroidal dipole resonance based on the source-representation, where the distribution of the induced charges and currents is characterized by the three families of electric, magnetic, and toroidal multipoles. On the other hand, the resonant optical force can also be completely attributed to an electric dipole resonance in the alternative field-representation, where the electromagnetic fields in the source-free region are expressed by two sets of electric and magnetic multipole fields based on symmetry. The confusion is resolved by conceptually introducing the irreducible electric dipole, toroidal dipole, and renormalized electric dipole. We demonstrate that the optical force is a powerful tool to identify toroidal response even when its scattering intensity is dwarfed by the conventional electric and magnetic multipoles.

  13. Goos-Hänchen shifts of the reflected waves from a cold, inhomogeneous, and magnetized plasma slab.

    Science.gov (United States)

    Xu, Guoding; Zang, Taocheng; Pan, Tao

    2010-01-01

    We discuss theoretically the Goos-Hänchen (GH) shifts of the reflected waves from a cold, inhomogeneous, and magnetized plasma slab by using the invariant imbedding approach. Aiming at the linear and parabolic electron-density profiles, we demonstrate numerically the dependences of the co- and cross-polarized GH shifts on the angle of incidence, external static magnetic field, and the thickness of the plasma slab. The results show that the different electron-density profiles of plasma can result in the very different dependences of the GH shifts on the angle of incidence, external magnetic field, and the slab's thickness; the GH shifts can be switched between the considerably large positive and negative values under certain conditions. Particularly, without altering the structure of the plasma slab, the GH shifts can be manipulated by modifying the angle of incident or the external static magnetic field.

  14. Self-assembled plasmonic core-shell clusters with an isotropic magnetic dipole response in the visible range.

    Science.gov (United States)

    Mühlig, Stefan; Cunningham, Alastair; Scheeler, Sebastian; Pacholski, Claudia; Bürgi, Thomas; Rockstuhl, Carsten; Lederer, Falk

    2011-08-23

    We theoretically analyze, fabricate, and characterize a three-dimensional plasmonic nanostructure that exhibits a strong and isotropic magnetic response in the visible spectral domain. Using two different bottom-up approaches that rely on self-organization and colloidal nanochemistry, we fabricate clusters consisting of dielectric core spheres, which are smaller than the wavelength of the incident radiation and are decorated by a large number of metallic nanospheres. Hence, despite having a complicated inner geometry, such a core-shell particle is sufficiently small to be perceived as an individual object in the far field. The optical properties of such complex plasmonic core-shell particles are discussed for two different core diameters.

  15. Finishing of the cold mass assembly

    CERN Multimedia

    Maximilien Brice

    2001-01-01

    Photo 1 Zoom of the lyre-side end of the active part assembly. The extremity of the shrinking cylinder has been bevelled in view of welding the end cover. Photo 2 General view of the finishing station showing the special supporting structures (blue and yellow structures) needed for the geometric measurements and for the alignment operations. Photo 3 Zoom of the lyre-side end of the active part assembly. One can also see the auxiliary bus bars needed to power the corrector magnets that are installed in the dipole cold mass assembly. Photo 4 Technicians are putting in order the instrumentation wires. The prototype magnets were equipped with numerous sensors to monitor key parameters during the performance tests at cold conditions.

  16. 600-T Magnetic Fields due to Cold Electron Flow in a simple Cu-Coil irradiated by High Power Laser pulses

    CERN Document Server

    Zhu, Baojun; Yuan, Dawei; Li, Yanfei; Li, Fang; Liao, Guoqian; Zhao, Jiarui; Zhong, Jiayong; Xue, Feibiao; Wei, Huigang; Zhang, Kai; Han, Bo; Pei, Xiaoxing; Liu, Chang; Zhang, Zhe; Wang, Weimin; Zhu, Jianqiang; Zhao, Gang; Zhang, Jie

    2015-01-01

    A new simple mechanism due to cold electron flow to produce strong magnetic field is proposed. A 600-T strong magnetic field is generated in the free space at the laser intensity of 5.7x10^15 Wcm^-2. Theoretical analysis indicates that the magnetic field strength is proportional to laser intensity. Such a strong magnetic field offers a new experimental test bed to study laser-plasma physics, in particular, fast-ignition laser fusion research and laboratory astrophysics.

  17. Roton dipole moment

    OpenAIRE

    Mineev, V. P.

    2009-01-01

    The roton excitation in the superfluid He-4 does not possess a stationary dipole moment. However, a roton has an instantaneous dipole moment, such that at any given moment one can find it in the state either with positive or with negative dipole moment projection on its momentum direction. The instantaneous value of electric dipole moment of roton excitation is evaluated. The result is in reasonable agreement with recent experimental observation of the splitting of microwave resonance absorpt...

  18. Vanishing of dipole matrix elements at level crossings.

    Science.gov (United States)

    Kocher, C. A.

    1972-01-01

    Demonstration that the vanishing of certain coupling matrix elements at level crossings follow from angular momentum commutation relations. A magnetic dipole transition having delta M = plus or minus 1, induced near a crossing of the levels in a nonzero magnetic field, is found to have a dipole matrix element comparable to or smaller than the quotient of the level separation and the field. This result also applies in the analogous electric field electric dipole case.

  19. Hybird of Quantum Phases for Induced Dipole Moments

    CERN Document Server

    Ma, Kai

    2016-01-01

    The quantum phase effects for induced electric and magnetic dipole moments are investigated. It is shown that the phase shift received by induced electric dipole has the same form with the one induced by magnetic dipole moment, therefore the total phase is a hybrid of these two types of phase. This feature indicates that in order to have a decisive measurement on either one of these two phases, it is necessary to measure the velocity dependence of the observed phase.

  20. Effect of annealing prior to cold rolling on magnetic and mechanical properties of low carbon non-oriented electrical steels

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez-Castaneda, E.J., E-mail: emmanuel.gutierrez@yahoo.com.mx [Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional (CINVESTAV-IPN), Department of Metallurgical Engineering and Materials Science, Carretera Saltillo-Monterrey, Km 13.5, 25900 Ramos Arizpe, Coahuila, P.O. Box 663, Saltillo Coahuila, 25000 (Mexico); Salinas-Rodriguez, A., E-mail: armando.salinas@cinvestav.edu.mx [Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional (CINVESTAV-IPN), Department of Metallurgical Engineering and Materials Science, Carretera Saltillo-Monterrey, Km 13.5, 25900 Ramos Arizpe, Coahuila, P.O. Box 663, Saltillo Coahuila, 25000 (Mexico)

    2011-10-15

    The effects of annealing prior to cold rolling on the microstructure, magnetic and mechanical properties of low-C grain non-oriented (GNO) electrical steels have been investigated. The grain structure of hot-rolled electrical steel strips is modified by annealing at temperatures between 700 and 1050 deg. C. Annealing at temperatures less than the ferrite to austenite+ferrite transformation temperature on heating (Ac{sub 1}) causes a marginal effect on the grain size. However, annealing in the intercritical region at temperatures between Ac{sub 1} and Ac{sub 3} (the ferrite+austenite to austenite transformation temperature on heating) causes rapid decarburization and development of large columnar ferrite grains free of carbide particles. This microstructure leads, after cold rolling and a fast annealing treatment, to carbide free, large ferrite grain microstructures with magnetic and mechanical properties superior to those observed typically in the same steel in the industrially fully processed condition. These results are attributed to the increment in grain size and to the {l_brace}1 0 0{r_brace} fiber texture developed during the final annealing at temperatures up to 850 deg. C. Annealing at higher temperatures, T>Ac{sub 3}, results in a strong {l_brace}1 1 1{r_brace} fiber texture and an increase of the quantity of second phase particles present in the microstructure, which lead to a negative effect on the final properties. The results suggest that annealing prior to cold rolling offers an attractive alternative processing route for the manufacture of fully processed low C GNO electrical steels strips. - Highlights: > Electrical steels are produced by an alternative processing route. > Annealing of the hot rolled electrical steel strips causes rapid decarburization. > Development of the <1 0 0>//ND texture results in better magnetic properties. > Magnetic properties of electrical steels depend on the grain size and texture. > Second phase particles and grain

  1. Cold Test Results of the Inner Triplet Orbit Correctors for the LHC

    CERN Document Server

    Venturini-Delsolaro, W

    2006-01-01

    The inner triplet orbit correctors for the LHC, MCBX and MCBXA, underwent acceptance tests at superfluid helium temperature at CERN, before shipping to FNAL for integration in the cold masses. A total of 27 MCBX (Horizontal-Vertical Dipole Correctors), of which 9 MCBXA (with nested Sextupole-Dodecapole insert), are needed for the LHC, including spares. The paper discusses the test protocols for series magnets, and reports the results of quench performance and cold magnetic measurements. The peculiarities of combined training and the hysteresis effects in the nested windings are presented, together with the search of the optimum setting procedure to minimize the persistent current effects on the beam dynamics.

  2. Optimization of Open Midplane Dipole Design for LHC IR Upgrade

    CERN Document Server

    Gupta, Ramesh C; Ghosh, Arup; Harrison, Michael; Mokhov, Nikolai V; Schmalzle, Jesse D; Wanderer, Peter

    2005-01-01

    The proposed ten-fold increase in Large Hadron Collider (LHC) luminosity requires high field (~15 T) magnets that are subjected to the high radiation power of ~9 kW/per beam directed towards each interaction region. This has a major impact in the design of first dipole in the "Dipole First" optics. The proposed design allows sufficient clear space between coils so that most of the particle showers from the interaction points (concentrated at the midplane due to strong magnetic field) can be transported outside the coil region to a warm absorber thus drastically reducing the peak power density in the coils and removing heat at a higher (nitrogen) temperature. The concept, however, presents several new technical challenges: (a) obtaining good field quality despite a large midplane gap, (b) minimizing peak fields on coil, (c) dealing with large vertical forces with no structure between the coils, (d) minimizing heat deposition in the cold region, (e) designing a support structure. Designs with different horizont...

  3. Blood flow and muscle bio-energetics by 31P-nuclear magnetic resonance after local cold acclimation.

    Science.gov (United States)

    Savourey, G; Clerc, L; Vallerand, A L; Leftheriotis, G; Mehier, H; Bittel, J H

    1992-01-01

    To clarify the origin of local cold adaptation and to define precisely its influence on muscle bio-energetics during local exercise, five subjects were subjected to repeated 5 degrees C cold water immersion of the right hand and forearm. The first aim of our investigation was therefore carried out by measuring local skin temperatures and peripheral blood flow during a cold hand test (5 degrees C, 5 min) followed by a 10-min recovery period. The 31P by nuclear magnetic resonance (31PNMR) muscle bio-energetic changes, indicating possible heat production changes, were measured during the recovery period. The second aim of our investigation was carried out by measuring 31PNMR muscle bioenergetics during handgrip exercise (10% of the maximal voluntary contraction for 5 min followed by a 10-min recovery period) performed both at a comfortable ambient temperature (22 degrees C; E) and after a cold hand test (EC), before and after local cold adaptation. Local cold adaptation, confirmed by warmer skin temperatures of the extremities (+30%, P less than 0.05), was related more to an increased peripheral blood flow, as shown by the smaller decrease in systolic peak [-245 (SEM 30) Hz vs -382 (SEM 95) Hz, P less than 0.05] than to a change in local heat production, because muscle bioenergetics did not vary. Acute local cold immersion decreased the inorganic phosphate:phosphocreatine (PC) ratio during EC compared to E [+0.006 (SEM 0.010) vs +0.078 (SEM 0.002) before acclimation and +0.029 (SEM 0.002) vs +0.090 (SEM 0.002) after acclimation respectively, P less than 0.05] without significant change in the PC:beta-adenosine triphosphate ratio and pH. Local adaptation did not modify these results statistically. The recovery of PC during E increased after acclimation [9.0 (SEM 0.2) min vs 3.0 (SEM 0.4) min, P less than 0.05]. These results suggested that local cold adaptation is related more to peripheral blood flow changes than to increased metabolic heat production in the muscle.

  4. Artificial abelian gauge potentials induced by dipole-dipole interactions between Rydberg atoms

    CERN Document Server

    Cesa, A

    2013-01-01

    We analyze the influence of dipole-dipole interactions between Rydberg atoms on the generation of abelian artificial gauge potentials and fields. When two Rydberg atoms are driven by a uniform laser field, we show that the combined atom-atom and atom-field interactions give rise to new, non-uniform, artificial gauge potentials. We identify the mechanism responsible for the emergence of these gauge potentials. Analytical expressions for the latter indicate that the strongest artificial magnetic fields are reached in the regime intermediate between the dipole blockade regime and the regime in which the atoms are sufficiently far apart such that atom-light interaction dominates over atom-atom interactions. We discuss the differences and similarities of artificial gauge fields originating from resonant dipole-dipole and van der Waals interactions. We also give an estimation of experimentally attainable artificial magnetic fields resulting from this mechanism.

  5. Axion induced oscillating electric dipole moments

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Christopher T. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-06-24

    In this study, the axion electromagnetic anomaly induces an oscillating electric dipole for any magnetic dipole. This is a low energy theorem which is a consequence of the space-time dependent cosmic background field of the axion. The electron will acquire an oscillating electric dipole of frequency ma and strength ~ 10-32 e-cm, within four orders of magnitude of the present standard model DC limit, and two orders of magnitude above the nucleon, assuming standard axion model and dark matter parameters. This may suggest sensitive new experimental venues for the axion dark matter search.

  6. Fictitious magnetic field gradients in optical microtraps as an experimental tool for interrogating and manipulating cold atoms

    CERN Document Server

    Albrecht, Bernhard; Clausen, Christoph; Dareau, Alexandre; Schneeweiss, Philipp; Rauschenbeutel, Arno

    2016-01-01

    Optical microtraps provide a strong spatial confinement for laser-cooled atoms. They can, e.g., be realized with strongly focused trapping light beams or the optical near fields of nano-scale waveguides and photonic nanostructures. Atoms in such traps often experience strongly spatially varying AC Stark shifts which are proportional to the magnetic quantum number of the respective energy level. These inhomogeneous fictitious magnetic fields can cause a displacement of the trapping potential that depends on the Zeeman state. Hitherto, this effect was mainly perceived as detrimental. However, it also provides a means to probe and to manipulate the motional state of the atoms in the trap by driving transitions between Zeeman states. Furthermore, by applying additional real or fictitious magnetic fields, the state-dependence of the trapping potential can be controlled. Here, using laser-cooled atoms that are confined in a nanofiber-based optical dipole trap, we employ this control in order to tune the microwave c...

  7. Cold nuclear fusion

    National Research Council Canada - National Science Library

    Huang Zhenqiang Huang Yuxiang

    2013-01-01

    ...... And with a magnetic moment of light nuclei controlled cold nuclear collide fusion, belongs to the nuclear energy research and development in the field of applied technology "cold nuclear collide fusion...

  8. Optical dipole trapping of radium atoms for EDM search

    Science.gov (United States)

    Trimble, W. L.; Sulai, I. A.; Parker, R. H.; Bailey, K.; Greene, J. P.; Holt, R. J.; Korsch, W.; Lu, Z.-T.; Mueller, P.; O'Connor, T. P.; Singh, J.

    2010-03-01

    We are developing an EDM search based on laser-cooled and trapped Ra-225 (half-life = 15 d) atoms. Due to octupole deformation of the nucleus, Ra-225 is predicted to be 2-3 orders of magnitude more sensitive to T-violating interactions than Hg-199, which currently sets the most stringent limits in the nuclear sector. Recently, we have succeeded in transferring Ra-226 atoms from a MOT into an optical dipole trap formed by a fiber laser beam at 1550 nm. For the EDM measurement, the cold atoms will be moved into the neighboring vacuum chamber inside magnetic shields where a pair of electrodes apply a 10 kV cm-1electric field. This work is supported by DOE, Office of Nuclear Physics under contract No. DE-AC02-06CH11357.

  9. Microstructural evolution in warm-rolled and cold-rolled strip cast 6.5 wt% Si steel thin sheets and its influence on magnetic properties

    Science.gov (United States)

    Wang, Xianglong; Liu, Zhenyu; Li, Haoze; Wang, Guodong

    2017-07-01

    6.5 wt% Si steel thin sheets were usually fabricated by warm rolling. In our previous work, 6.5 wt% Si steel thin sheets with good magnetic properties had been successfully fabricated by cold rolling based on strip casting. In the present work, the main purposes were to find out the influences of warm rolling and cold rolling on microstructures and magnetic properties of the thin sheets with the thickness of 0.2 mm, and to confirm which rolling method was more suitable for fabricating 6.5 wt% Si steel thin sheets. The results showed that the cold rolled sheet could obtain good surface quality and flatness, while the warm rolled sheet could not. The intensity of γ-fiber rolling texture (//ND) of cold rolled specimen was weaker than that of the warm rolled specimen, especially for the {1 1 1} component at surface layer and {1 1 1} component at center layer. After the same annealing treatment, the cold rolled specimen, which had higher stored energy and weaker intensity of γ-fiber rolling texture, could obtain smaller recrystallization grain size, weaker intensity of γ-fiber recrystallization texture and stronger intensity of λ-fiber recrystallization texture. Therefore, due to the good surface quality, smaller recrystallization grain size and optimum recrystallization texture, the cold rolled specimen possessed improved magnetic properties, and cold rolling should be more suitable for fabricating 6.5 wt% Si steel thin sheets.

  10. What do we do, if some of the MICE magnets can't be kept cold using the two-stage coolers?

    Energy Technology Data Exchange (ETDEWEB)

    Green, Michael A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2011-01-26

    Tests of the spectrometer solenoids have not been encouraging in terms of keeping the magnets cold using three 1.5 W (at 4.2 K) coolers. The spectrometer solenoids are being rebuilt with additional cooling capacity at 4.2 K. It is hoped that there will be sufficient 4.2 K cooling to keep the magnets cold. The spectrometer solenoids can be kept cold using liquid helium (up to a boil-off of 20 liters per day). This option does not apply for the other magnets in the MICE cooling channel, because there is not enough liquid helium storage within the magnet cold mass. It is important that the MICE collaboration ask the question, “How do we keep the MICE cooling channel magnets cold, if there isn’t sufficient cooling from the 4.2 K coolers?” This report discusses the cooling requirements at both 40 K and 4.2 K for all three types of MICE cooling channel magnets. This report discusses the steps that must be taken in the magnet fabrication to permit the magnets to be cooled using a small (20 to 40 W) external 4.2 K Claude cycle refrigerator. One must also ask the question as to whether there is enough excess capacity in the decay solenoid refrigerator to cool some of the MICE magnets. A plan for cooling the magnets using a Linde 1400 series refrigerator is presented. A plan for increasing the 4.4 K refrigeration from the existing decay solenoid refrigerator is also presented.

  11. Thermo-magneto coupling in a dipole plasma

    CERN Document Server

    Yoshida, Z; Morikawa, J; Saitoh, H

    2012-01-01

    On a dipole plasma, we observe the generation of magnetic moment, as the movement of the levitating magnet-plasma compound, in response to electron-cyclotron heating and the increase of $\\beta$ (magnetically-confined thermal energy). We formulate a thermodynamic model with interpreting heating as injection of microscopic magnetic moment; the corresponding chemical potential is the ambient magnetic field.

  12. Preparation of cold ions in strong magnetic field and its application to gas-phase NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fuke, K., E-mail: fuke@kobe-u.ac.jp [Institute for Molecular Science (Japan); Ohshima, Y. [Tokyo Institute of Technology, Department of Chemistry (Japan); Tona, M. [Ayabo Co. Fukukama (Japan)

    2015-11-15

    Nuclear Magnetic Resonance (NMR) technique is widely used as a powerful tool to study the physical and chemical properties of materials. However, this technique is limited to the materials in condensed phases. To extend this technique to the gas-phase molecular ions, we are developing a gas-phase NMR apparatus. In this note, we describe the basic principle of the NMR detection for molecular ions in the gas phase based on a Stern-Gerlach type experiment in a Penning trap and outline the apparatus under development. We also present the experimental procedures and the results on the formation and the manipulation of cold ions under a strong magnetic field, which are the key techniques to detect the NMR by the present method.

  13. Preparation of cold ions in strong magnetic field and its application to gas-phase NMR spectroscopy

    Science.gov (United States)

    Fuke, K.; Ohshima, Y.; Tona, M.

    2015-11-01

    Nuclear Magnetic Resonance (NMR) technique is widely used as a powerful tool to study the physical and chemical properties of materials. However, this technique is limited to the materials in condensed phases. To extend this technique to the gas-phase molecular ions, we are developing a gas-phase NMR apparatus. In this note, we describe the basic principle of the NMR detection for molecular ions in the gas phase based on a Stern-Gerlach type experiment in a Penning trap and outline the apparatus under development. We also present the experimental procedures and the results on the formation and the manipulation of cold ions under a strong magnetic field, which are the key techniques to detect the NMR by the present method.

  14. RHIC AC DIPOLE DESIGN AND CONSTRUCTION.

    Energy Technology Data Exchange (ETDEWEB)

    BAI,M.; METH,M.; PAI,C.; PARKER,B.; PEGGS,S.; ROSER,T.; SANDERS,R.; TRBOJEVIC,D.; ZALTSMAN,A.

    2001-06-18

    Two ac dipoles with vertical and horizontal magnetic field have been proposed at RHIC for applications in linear and non-linear beam dynamics and spin manipulations. A magnetic field amplitude of 380 Gm is required to produce a coherent oscillation of 5 times the rms beam size at the top energy. We take the ac dipole frequency to be 1.0% of the revolution frequency away from the betatron frequency. To achieve the strong magnetic field with minimum power loss, an air-core magnet with two seven turn winding of low loss Litz wire resonating at 64 kHz is designed. The system is also designed to allow one to connect the two magnet winding in series to resonate at 37 kHz for the spin manipulation. Measurements of a half length prototype magnet are also presented.

  15. Trapped field internal dipole superconducting motor generator

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Downers Grove, IL)

    2001-01-01

    A motor generator including a high temperature superconductor rotor and an internally disposed coil assembly. The motor generator superconductor rotor is constructed of a plurality of superconductor elements magnetized to produce a dipole field. The coil assembly can be either a conventional conductor or a high temperature superconductor. The superconductor rotor elements include a magnetization direction and c-axis for the crystals of the elements and which is oriented along the magnetization direction.

  16. Ab initio calculations of NMR shielding of Sc3+, Y3+ and La3+ ions in the water solution and 45Sc, 89Y, 138La and 139La nuclear magnetic dipole moments

    Science.gov (United States)

    Antušek, Andrej; Šulka, Martin

    2016-09-01

    Ab initio calculations of NMR shielding constants for water solvated trivalent scandium, yttrium and lanthanum cations are presented. The solvent effects of the first solvation shell are calculated explicitly using coupled cluster theory. The relativistic correction is calculated at non-correlated level. The influence of the second solvation shell is estimated at DFT level. The final NMR shielding constants define new NMR absolute shielding scales of scandium, yttrium and lanthanum and these shieldings were used for re-derivation of the nuclear magnetic dipole moments, eliminating long standing errors of ≈ 0.005μN .

  17. "Cold" dispersion relation of corrugated waveguide filled with plasma immersed in a finite magnetic field

    Institute of Scientific and Technical Information of China (English)

    李伟; 魏彦玉; 谢鸿全; 刘盛纲; 巩马理

    2003-01-01

    A general dispersion equation of a partially filled plasma corrugated waveguide immersed in a finite magnetic field is presented. When the guiding magnet Bo →∞ or 0, this equation can be reduced to the results obtained in previous works.

  18. The methods of the LHC magnets' magnetic axis location measurement

    Energy Technology Data Exchange (ETDEWEB)

    Bottura, L.; Buzio, M.; Deferne, G.; Sievers, P.; Smirnov, N.; Villar, F.P.; Walckiers, L. [CERN, Conseil Europeen pour la recherche nucleaire, Laboratoire europeen pour la physique des particules, Geneve (Switzerland)

    1999-07-01

    More than 8 thousands LHC magnets of various types will be extensively measured during series magnetic test at both room and superfluid helium temperature. The precise knowledge of the magnetic axis positioning is vital for the alignment of those magnets in the tunnel. The most efficient and cost effective method with rotating pick up coil is chosen currently as a baseline for series measurement. The position of the measuring coil axis herewith is measured with a dedicated optical system. The deflection of the light beam in the air due to temperature gradient either passing through the cold bore when the magnet excited for warm measurement or through the anti-cryostat during cold measurement can reach magnitudes significantly exceeding tolerance and therefore is a critical issue. We present studies of the light deflection in 10 m long dipole at warm and cold and propose means to reduce it. The result of the dipole centring powered in Quadrupole Configured Dipole (QCD) or 'ugly quad' configuration and correlation with centring based on high order harmonics are presented as well. (authors)

  19. LHC dipoles: the countdown has begun

    CERN Multimedia

    Patrice Loiez

    2002-01-01

    At the entrance to the fourth floor corridor of the LHC-MMS (Main Magnets and Superconductors) Group in building 30, the Director-General has unveiled an electronic information panel indicating the number of LHC dipoles still to be delivered and the days remaining to the deadline (30 June 2006). The panel was the idea of Lucio Rossi, leader of the MMS Group, which is responsible for the construction of the dipole magnets. The unveiling ceremony took place on the morning of Friday 11 October 2002, at the end of a drink held to celebrate with MMS group and the LHC top management the exceptional performance of the latest dipoles, built by the French consortium Alstom-Jeumont. They are the first dipoles to achieve a magnetic field of 9 tesla in one go without quenching, thus exceeding the nominal operating field of 8.3 tesla. The challenge is now to increase the production rate from 2 to 35 dipoles per month by 2004 in order to meet the deadline, while maintaining this quality. Photo 01: The Director-General Luci...

  20. The noncommutative effects on the dipole moments of fermions in the standard model

    OpenAIRE

    Iltan, E.

    2003-01-01

    We study the dipole moments, electric dipole moment, weak electric dipole moment, anomalous magnetic moment, anomalous weak magnetic moment, of fermions in the noncommutative extension of the SM. We observe that the noncommutative effects are among the possible candidates to explain the electric and weak electric dipole moment of fermions. Furthermore, the upper bounds for the parameters which carry space-time and space-space noncommutativity can be obtained by using the theoretical and exper...

  1. Cooling Scheme for BNL-Built LHC Magnets

    CERN Document Server

    Ostojic, R; Van Weelderen, R; Willen, E H; Wu, K C

    1999-01-01

    Brookhaven National Laboratory (BNL) will provide four types of magnets, identified as D1, D2, D3 and D4, for the Insertion Regions of the Large Hadron Collider (LHC) as part of an international collaboration. These magnets utilize the dipole coil design of the Relativistic Heavy Ion Collider (RHIC) at BNL, for performance, reliability and cost reasons. The magnet cold mass and cryostat have been designed to ensure that these magnets meet all performance requirements in the LHC sloped tunnel using its cryogenic distribution system. D1 is a RHIC arc dipole magnet. D2 and D4 are 2-in-1 magnets, two coils in one cold mass, in a cryostat. D3 is a 1-in-1 magnet, one coil in one cold mass, with two cold masses side by side in a cryostat. D1 and D4 will be cooled by helium II at 1.9 K using a bayonet heat exchanger similar to the main cooling system of LHC. D2 and D3 will be cooled by liquid helium at 4.5 K using a Two-Feed scheme. A detailed description of the cooling scheme for these magnets, their cryostats, spec...

  2. A proposal for sympathetically cooling neutral molecules using cold ions

    CERN Document Server

    Robicheaux, F

    2014-01-01

    We describe a method for cooling neutral molecules that have magnetic and electric dipole moments using collisions with cold ions. An external magnetic field is used to split the ground rovibrational energy levels of the molecule. The highest energy state within the ground rovibrational manifold increases in energy as the distance to the ion decreases leading to a repelling potential. At low energy, inelastic collisions are strongly suppressed due to the large distance of closest approach. Thus, a collision between a neutral molecule and a cold ion will lead to a decrease in the molecule's kinetic energy with no change in internal energy. We present results for the specific case of OH molecules cooled by Be$^+$, Mg$^+$, or Ca$^+$ ions.

  3. 磁尺在冷连轧系统中的应用%Application of SONY Magnetic Scale in Cold Tandem Rolling Mill

    Institute of Scientific and Technical Information of China (English)

    张霆

    2013-01-01

      介绍磁尺在某冷连轧机组中作为 AGC 系统的位移传感器的应用方法。%The article describes how SONY Magnetic Scale works as position transducer in the AGC system of a cold tandem rolling mill.

  4. Creation of effective magnetic fields in optical lattices The Hofstadter butterfly for cold neutral atoms

    CERN Document Server

    Jaksch, D

    2003-01-01

    We investigate the dynamics of neutral atoms in a 2D optical lattice which traps two distinct internal states of the atoms in different columns. Two Raman lasers are used to coherently transfer atoms from one internal state to the other, thereby causing hopping between the different columns. By adjusting the laser parameters appropriately we can induce a non vanishing phase of particles moving along a closed path on the lattice. This phase is proportional to the enclosed area and we thus simulate a magnetic flux through the lattice. This setup is described by a Hamiltonian identical to the one for electrons on a lattice subject to a magnetic field and thus allows us to study this equivalent situation under very well defined controllable conditions. We consider the limiting case of huge magnetic fields -- which is not experimentally accessible for electrons in metals -- where a fractal band structure, the Hofstadter butterfly, characterizes the system.

  5. Magnetic-field-driven localization of light in a cold-atom gas

    CERN Document Server

    Skipetrov, S E

    2014-01-01

    We discover a transition from extended to localized quasi-modes for light in a gas of immobile two-level atoms in a magnetic field. The transition takes place either upon increasing the number density of atoms in a strong field or upon increasing the field at a high enough density. It has many characteristic features of a disorder-driven (Anderson) transition but is strongly influenced by near-field interactions between atoms and the anisotropy of the atomic medium induced by the magnetic field.

  6. Quadrupole magnet for a rapid cycling synchrotron

    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

    Rapid Cycling Synchrotrons (RCS) feature interleaved warm and cold dipole magnets; the field of the warm magnets is used to modulate the average bending field depending on the particle energy. It has been shown that RCS can be an attractive option for fast acceleration of particles, for example, muons, which decay quickly. In previous studies it was demonstrated that in principle warm dipole magnets can be designed which can provide the required ramp rates, which are equivalent to frequencies of about 1 kHz. To reduce the losses it is beneficial to employ two separate materials for the yoke; it was also shown that by employing an optimized excitation coil geometry the eddy current losses are acceptable. In this paper we show that the same principles can be applied to quadrupole magnets targeting 30 T/m with a repetition rate of 1kHz and good field quality.

  7. Superconducting magnets for the LHC main lattice

    CERN Document Server

    Rossi, L

    2004-01-01

    The main lattice of the Large Hadron Collider (LHC) will employ about 1600 main magnets and more than 4000 corrector magnets. All superconducting and working in pressurized superfluid helium bath, these impressive line of magnets will fill more than 20 km of the underground tunnel. With almost 70 main dipoles already delivered and 10 main quadrupoles almost completed, we passed the 5% of the production and now all manufacturers have fully entered into series production. In this paper the most critical issues encountered in the ramping up in such a real large scale fabrication will be addressed: uniformity of the coil size and of prestress, special welding technique, tolerances on curvature (dipoles) or straightness (quadrupoles) and of the cold mass extremities, harmonic content and, most important, the integrated field uniformity among magnets. The actual limits and the solution for improvements will be discussed. Finally a realistic schedule based on actual achievements is presented.

  8. Diamond dipole active antenna

    OpenAIRE

    Bubnov, Igor N.; Falkovych, I. S.; Gridin, A. A.; Stanislavsky, A. A.; Reznik, A. P.

    2015-01-01

    Advantages of the diamond dipole antenna as an active antenna are presented. Such an antenna is like an inverted bow-tie antenna, but the former has some advantages over the ordinary bow-tie antenna. It is shown that the diamond dipole antenna may be an effective element of a new antenna array for low-frequency radio astronomy as well as a communication antenna.

  9. Bent Solenoids with Superimposed Dipole Fields

    Energy Technology Data Exchange (ETDEWEB)

    Meinke, Rainer, B.; Goodzeit, Carl, L.

    2000-03-21

    A conceptual design and manufacturing technique were developed for a superconducting bent solenoid magnet with a superimposed dipole field that would be used as a dispersion device in the cooling channel of a future Muon Collider. The considered bent solenoid is equivalent to a 180° section of a toroid with a major radius of ~610 mm and a coil aperture of ~416 mm. The required field components of this magnet are 4 tesla for the solenoid field and 1 tesla for the superimposed dipole field. A magnet of this size and shape, operating at these field levels, has to sustain large Lorentz forces resulting in a maximum magnetic pressure of about 2,000 psi. A flexible round mini-cable with 37 strands of Cu-NbTi was selected as the superconductor. Detailed magnetic analysis showed that it is possible to obtain the required superimposed dipole field by tilting the winding planes of the solenoid by ~25°. A complete structural analysis of the coil support system and the helium containment vessel under thermal, pressure, and Lorentz force loads was carried out using 3D finite element models of the structures. The main technical issues were studied and solutions were worked out so that a highly reliable magnet of this type can be produced at an affordable cost.

  10. Diagnostics of the Fermilab Tevatron using an AC dipole

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, Ryoichi [Univ. of Texas, Austin, TX (United States)

    2008-08-01

    The Fermilab Tevatron is currently the world's highest energy colliding beam facility. Its counter-rotating proton and antiproton beams collide at 2 TeV center-of-mass. Delivery of such intense beam fluxes to experiments has required improved knowledge of the Tevatron's beam optical lattice. An oscillating dipole magnet, referred to as an AC dipole, is one of such a tool to non-destructively assess the optical properties of the synchrotron. We discusses development of an AC dipole system for the Tevatron, a fast-oscillating (f ~ 20 kHz) dipole magnet which can be adiabatically turned on and off to establish sustained coherent oscillations of the beam particles without affecting the transverse emittance. By utilizing an existing magnet and a higher power audio amplifier, the cost of the Tevatron AC dipole system became relatively inexpensive. We discuss corrections which must be applied to the driven oscillation measurements to obtain the proper interpretation of beam optical parameters from AC dipole studies. After successful operations of the Tevatron AC dipole system, AC dipole systems, similar to that in the Tevatron, will be build for the CERN LHC. We present several measurements of linear optical parameters (beta function and phase advance) for the Tevatron, as well as studies of non-linear perturbations from sextupole and octupole elements.

  11. Complete electric dipole response in 208Pb

    CERN Document Server

    Tamii, A; von Neumann-Cosel, P; Fujita, Y; Adachi, T; Bertulani, C A; Carter, J; Dozono, M; Fujita, H; Fujita, K; Hatanaka, K; Heilmann, A M; Ishikawa, D; Itoh, M; Ong, H J; Kawabata, T; Kalmykov, Y; Litvinova, E; Matsubara, H; Nakanishi, K; Neveling, R; Okamura, H; Özel-Tashenov, B; Ponomarev, V Yu; Richter, A; Rubio, B; Sakaguchi, H; Sakemi, Y; Sasamoto, Y; Shimbara, Y; Shimizu, Y; Smit, F D; Suzuki, T; Tameshige, Y; Wambach, J; Yamada, R; Yosoi, M; Zenihiro, J

    2011-01-01

    A benchmark experiment on 208Pb shows that polarized proton inelastic scattering at very forward angles including 0{\\deg} is a powerful tool for high-resolution studies of electric dipole (E1) and spin magnetic dipole (M1) modes in nuclei over a broad excitation energy range testing up-to-date nuclear model calculations. The E1 polarizability extracted from the data provides a constraint on the neutron skin thickness in 208Pb and the poorly known density dependence of the symmetry energy, relevant to the description of neutron stars.

  12. Fatigue Quantity Analysis of Mining Steel Rope Based on Magnetic Dipole%基于磁偶极子的矿用钢丝绳疲劳定量分析

    Institute of Scientific and Technical Information of China (English)

    杨波

    2016-01-01

    矿用钢丝绳的疲劳损伤主要是断丝,为了能够定量判断矿用钢丝绳的损伤强度,运用电流环磁偶极子作为理论模型,根据磁记忆检测理论推导出了钢丝绳损伤区域磁场分布,得出了矿用钢丝绳疲劳裂纹各个参数对金属磁记忆信号的影响。%The primary fatigue damage of mining steel rope is wire breaking. Circuit and magnetic dipole as a theoretical model, magnetic memory is used to induce the magnetic field distribution of the damage zone in order to quantitatively assess the damage strength of the mining steel rope. On the metal magnetic memory signals, the effect of the fatigue crack parameters of the steel rope was obtained.

  13. Design Studies and Optimization of High-Field Nb$_3$Sn Dipole Magnets for a Future Very High Energy PP Collider

    Energy Technology Data Exchange (ETDEWEB)

    Kashikhin, V. V. [Fermilab; Novitski, I. [Fermilab; Zlobin, A. V. [Fermilab

    2017-05-01

    High filed accelerator magnets with operating fields of 15-16 T based on the $Nb_3Sn$ superconductor are being considered for the LHC energy upgrade or a future Very High Energy pp Collider. Magnet design studies are being conducted in the U.S., Europe and Asia to explore the limits of the $Nb_3Sn$ accelerator magnet technology while optimizing the magnet design and performance parame-ters, and reducing magnet cost. The first results of these studies performed at Fermilab in the framework of the US-MDP are reported in this paper.

  14. IMPROVEMENT OF EXPRESSION FOR EXCITATION BY AN ELECTRIC DIPOLE IN GTEM CELL

    Institute of Scientific and Technical Information of China (English)

    Ren Liehui; Chen Zhiyu

    2002-01-01

    On the basis of Wilson's work in which the vertical electric dipole is centrally located in GHz Transverse ElectroMagnetic (GTEM) cell, we deduce the expression for the field distribution excited by an electric dipole in the case that the dipole is not centrally located. It will be useful for EMC measurements using GTEM cell.

  15. Detailed discussion of a linear electric field frequency shift induced in confined gases by a magnetic field gradient: Implications for neutron electric-dipole-moment experiments

    Science.gov (United States)

    Lamoreaux, S. K.; Golub, R.

    2005-03-01

    The search for particle electric dipole moments (EDM’s) is one of the best places to look for physics beyond the standard model of electroweak interaction because the size of time reversal violation predicted by the standard model is incompatible with present ideas concerning the creation of the baryon-antibaryon asymmetry. As the sensitivity of these EDM searches increases more subtle systematic effects become important. We develop a general analytical approach to describe a systematic effect recently observed in an electric dipole moment experiment using stored particles [J. M. Pendlebury , Phys. Rev. A 70, 032102 (2004)]. Our approach is based on the relationship between the systematic frequency shift and the velocity autocorrelation function of the resonating particles. Our results, when applied to well-known limiting forms of the correlation function, are in good agreement with both the limiting cases studied in recent work that employed a numerical and heuristic analysis. Our general approach explains some of the surprising results observed in that work and displays the rich behavior of the shift for intermediate frequencies, which has not been studied previously.

  16. Energy Extraction Resistors for the Main Dipole and Quadrupole Circuits of the LHC

    CERN Document Server

    Dahlerup-Petersen, K; Popov, V; Sytchev, V V; Vasilev, L B; Zubko, V G

    2000-01-01

    When the LHC will be operating at its maximum beam energy, its superconducting dipole chains store a total magnetic energy of more than 11 GJ. At the same time, the QF and QD quadrupole circuits store a total energy of 400 MJ. Even with the sectorisation of each of the three principal power circuits into eight individually powered segments, the stored energy of a single circuit is considerable. During normal operation the energy in the dipole circuits is safely returned to the mains grid, using the thyristor-based, 'booster' unit of the power converters, operating in inversion. For the quadrupole chains, where the converter is of a mono-polar topology, the stored energy is dissipated into the resistive part of the warm d.c. power lines (busbars and cables) in a slow, controlled run-down. When a magnet quenches, however, such a slow energy transfer, taking 20 minutes from the rated LHC current, will not be possible. The 'cold' diode, taking over the magnet current in case of a quench, will not survive this slo...

  17. submitter Training Behavior of the Main Dipoles in the Large Hadron Collider

    CERN Document Server

    Todesco, Ezio; Bajko, Marta; Bottura, Luca; Bruning, Oliver; De Rijk, Gijs; Fessia, Paolo; Hagen, Per; Naour, Sandrine Le; Modena, Michele; Perez, Juan Carlos; Rossi, Lucio; Schmidt, Rudiger; Siemko, Andrzej; Tock, Jean-Philippe; Tommasini, Davide; Verweij, Arjan; Willering, Gerard

    2017-01-01

    In 2015, the 1232 Nb-Ti dipole magnets in the Large Hadron Collider (LHC) have been commissioned to 7.8 T operational field, with 172 quenches. More than 80% of these quenches occurred in the magnets of one of the three cold mass assemblers (3000 series), confirming what was already observed in 2008. In this paper, the recent analysis carried out on the quench performance of the Large Hadron Collider dipole magnets is reported, including the individual reception tests and the 2008 and 2015 commissioning campaigns, to better understand the above-mentioned anomaly and give an outlook for future operation and possible increase of the operational field. The lower part of the quench probability spectrum is compatible with Gaussian distributions; therefore, the training curve can be fit through error functions. An essential ingredient in this analysis is the estimate of the error to be associated with the training data due to sampling of rare events, allowing to test different hypothesis. Using this approach, an es...

  18. Dipole strength distribution of {sup 50}Ti

    Energy Technology Data Exchange (ETDEWEB)

    Gayer, Udo; Beck, Tobias; Beller, Jacob; Mertes, Laura; Pai, Haridas; Pietralla, Norbert; Ries, Philipp; Romig, Christopher; Werner, Volker; Zweidinger, Markus [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany)

    2015-07-01

    A first nuclear resonance fluorescence (NRF) experiment with a 68% isotopically enriched {sup 50}Ti target has been performed at the superconducting Darmstadt electron linear accelerator S-DALINAC to investigate particle-bound dipole excitations in this nucleus. The target was irradiated with an unpolarized bremsstrahlung photon beam at endpoint energies of 7.5 MeV and 9.7 MeV. The observed excited states are analyzed with respect to their excitation energies, spin quantum numbers and transition strengths. A complementary NRF experiment with polarized photons will be conducted at the High Intensity gamma-ray Source in Durham, NC, USA to determine the polarity of the dipole transitions. Data will be analyzed with regard to the Pygmy Dipole Resonance, a weakly-collective electric dipole excitation which starts to form in nuclei of this mass region. The measured transition strengths will be compared to microscopic calculations in the quasiparticle-phonon model. The investigation of the magnetic dipole strength distribution will focus on strong spin-flip transitions between the p,f spin-orbit partners expected in the nuclear shell model. First results of the measurements and the evaluation will be presented and discussed.

  19. Adjustable microchip ring trap for cold atoms and molecules

    CERN Document Server

    Baker, Paul M; Squires, Matthew B; Scoville, James A; Carlson, Evan J; Buchwald, Walter R; Miller, Steven M

    2009-01-01

    We describe the design and function of a circular magnetic waveguide for deBroglie waves produced from wires on a microchip. The guide is a two-dimensional magnetic minimum for trapping weak-field seeking states of atoms or molecules with a magnetic dipole moment. The design consists of seven circular wires sharing a common radius. We describe the design, the time-dependent currents of the wires and show that it is possible to form a circular waveguide with adjustable height and gradient while minimizing perturbation resulting from leads or wire crossings. This maximal area geometry is suited for rotation sensing with atom interferometry via the Sagnac effect using either cold atoms, molecules and Bose-condensed systems.

  20. Experiments with Dipole Antennas

    Science.gov (United States)

    Kraftmakher, Yaakov

    2009-01-01

    Employment of a data-acquisition system for data collection and calculations makes experiments with antennas more convenient and less time consuming. The determined directional patterns of the dipole antennas of different lengths are in reasonable agreement with theory. The enhancement of the signal by using a reflector is demonstrated, and a…